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Offline bootstrapTopic starter

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New Pick and Place design ideas
« on: May 08, 2016, 08:55:50 am »
Quote from: rx8pilot on May 08, 2016, 05:37:06 am
Quote from: bootstrap on May 08, 2016, 03:07:27 am
Quote from: mrpackethead on May 08, 2016, 02:59:02 am
With all that experience, you should build one.

I am so, so tempted to do so, partly because I need one (lame excuse), but mostly because I am finding the various aspects of pick-and-place machine operation fascinating.  And as a few of my recent posts indicate, there appears to be enormous opportunities to create different configurations of pick-and-place machines to make cheaper precise [but probably not fast] units.

Frankly, if I had one or two talented partners on such a project, I'd probably buckle and go for it.  I wouldn't be surprised if we could build a new pick-and-place machine from scratch for roughly the same I will probably spend on the complete production line (stencil-printer, pick-and-place, and reflow-oven).  As with most projects, the problem is TIME.

REPLY #1 of #2 (hopefully).

Do you need a P&P machine to assemble PCB's in-house or an all new business? I would have a ton of fun with the challenge of designing and building a P&P machine. I have a lot of experience designing and building very high precision mechanics for imaging and motion control. Now I design electronics and write embedded software most of the time. It would still take a mountain of time and money to do it with no guarantees. It would literally be an all new career to go down that path with the remarkably lofty goal of making MyData performance for low cost.

Seriously. Skip the N4 based on what you seem to require. You will be looking for a tall bridge to jump off of if you really need very fine pitch assembly as a reliable process. I don't have an N4, but I do have a Quad 4000C. The design of my machine goes back to the 80's and went out of production in the late 90's. PPM purchased the remnants of the company and started an update program for the software. Without getting too distracted with details - they definitely improved the machine and it is capable of placing 1005's. I am not suggesting you buy the same machine, but something like it. It is ridiculous (in my humble opinion) to consider one of the lowest cost/quality P&P machines on the market and expect it to nail PCB's with 0201 and .3mm without constant fiddling and re-work. You really can't be surprised that the moco subsystem is open loop steppers either - there is no money to put them in there. The PPM machine is steppers with linear encoders and a side scanner for alignment on the fly. Up vision for big parts and BGA. It is not fast, but is precise. With all that said, the small passive parts require the super precision feeders  - there is no way around that. The placement accuracy of the machine is meaningless if it struggles to pickup the parts in the first place. If the nozzle picks up on the edge of the component, it will flip or be at an angle causing a pick failure. You can only solve that by have very precise feeders that put the part in the exact same location every time and it has to be gentle about it. If the feeder is bumpy, the parts will jump out of the pocket before the head even arrives. From what I have read so far in this thread, the biggest weakness of the N4 is the feeders. For the price it seems pretty good. The Quad precision 8mm feeders are about $800ea which is still rather cheap when compared to the high-end machines - but they can index 2mm very precisely and smoothly.

I would not try to satisfy your requirements for under 80k with feeders, printer, oven, training, vacuum/air, accessories, etc. . If you are industrious like I was, you can get a broken machine and fix it up. That allowed me to get a 1005 capable machine with about 60 feeders for under $10k in cash - but it took nearly 10 months of nights and weekends to get it up and running. To buy it from PPM with with all the feeders and other parts would have been about $50-60k and would be ready to go on the first day. I also looked at DDM Novastar and liked them in general. They are targeted towards low volume and only the bigger machines can deal with 0201 (so it seems). What I did not like is that they cannot hold very many parts at a time. The Quad I have now can handle a TON of parts so I can have 6 designs ready to roll (in the machine) at any time and still be able to do prototypes without tearing the machine apart. That is super critical in my case where I do small batches of a bunch of different designs and don't want to have to setup each one every time I need a batch.

How much is your time worth and what business are you in?



I discussed some of my background in message #1002 above.  The short version is, I've been a self-employed scientist, engineer, inventor, product developer since before I finished school.  Once in a while over the years I've also taken project-specific contracts from places like NASA, AirForceResearchLabs and astronomical observatories.  My background seems somewhat similar to yours.

Like mrpackethead, pick-and-place intrigues me.  I know I shouldn't spend the time that will be required for a pick-and-place project, but then again, I almost always do projects that interest me somehow and avoid money generator projects.  That's one of my weak points (from some perspectives).

A year or two ago I designed a manual pick-and-place machine capable of handling 0201s and 0.50mm pitch components, which would have cost only $500 or so to build (as memory serves).  But I decided not to carry forward and finish that project... though I can't remember why.  Almost certainly it was to do other work that was more important (to me and financially).  It was a clever design, which is obviously necessary to do what needed to be done at such a low cost.

Part of the approach of that design also involved cameras, which I think may be the key to designing a modest cost pick-and-place machine capable of 0201 or smaller and 0.30mm to 0.50mm pitch BGA/QFN/etc.

Years ago I used to do lots of "hardware projects" (meaning "electronics + mechanics").  But I've been busy with software projects for a few years, and in that time pretty much all non-trivial components that interest me have become SMT only... or the SMT packages are much better (smaller, etc).

So the answer to your question is this.  I want to make several hardware projects again, but can't assemble them by hand like I used to with through-hole components.  I was going to have the prototypes for my first device assembled by an assembly house, but when I finished the PCB layouts, purchased the components, and went to give the assembly house the job they had quoted a few months before... they demanded somewhere between 5 and 10 times more per PCB for assembly.  That royally pissed me off, and made me decide that if I was going to make several hardware projects, I should be able to do assembly myself.  That's what got me to investigate SMT technologies, equipment and devices, including pick-and-place.  So my answer is, the equipment is for assembling my prototypes over the next few years.

As per my usual practice, I wouldn't do a project like this unless we came up with a "design breakthrough" of some kind.  And I'm not interested in making something for the hobby market (in the sense it must handle 0201 and 0.5mm pitch to interest me).  But a "design breakthrough" doesn't mean something totally new (like the solder-paste jet printer from MyData seems to have been)... it could just mean a new approach that radically cuts the cost of a precision machine (but can be slower than existing commercial machines).  My target would be dozens or hundreds per year of real and wannabe independent electronics engineers (and startup/micro-companies) who no way can [afford to buy equipment to] assemble their own PCBs today (assuming they aren't just making trivial PCBs with large components).

In other words, no way do I want to even attempt to compete with MyData!!!  No way, no how, not even close.  And at the cost/price point I suspect we're both thinking of, I'm quite confident MyData won't want to compete with us either.  For years I could make very sophisticated electronics devices (including complete computer systems including CPUs that I designed myself (including instruction set) and built with MSI and SSI).  Maybe the new generation of young electronics engineers think "no way can I do those kinds of projects"... OR... "no way can I adopt the latest and greatest components".  My purpose would be to go "back to the future" where pretty much anyone could develop their own state-of-the-art devices... like I did years and decades ago.

Though I don't claim we need to stick to this notion, my general feeling is the target price is $5K to $10K but able to support just about any modern component.  I'd like to even go one step smaller than 0201, but for now that's optional.

Like all my projects, whether I happened to do it alone or in collaboration with one or more smart, experienced folks like you, I'd put off the final decision to "go for it" or not until we have a final design.  If it isn't a breakthrough in some way or other, then I definitely won't invest the time and money to build prototypes.  You seem like a realist, so you probably think the same way.

Incidentally, what I would like to do is create something that competes with MyData in terms of "what size and range of components it can reliably place", but DEFINITELY NOT in terms of speed (probably by a factor of 5x to 20x).  Well, unless we make a much bigger breakthrough than I envision, which I seriously doubt (but isn't 100% impossible).

Like you said, the current designs for pick-and-place machines were developed when there was no such thing as "very cheap cameras".  In fact, it appears to me like pick-and-place systems with cameras are essentially earlier configurations updated with cameras.  Which is a very valuable improvement, but didn't change the mechanical configuration or the essentials of how the whole device works.  Which is why I see a HUGE opening for new approaches (for anyone designing with a totally clean slate, not just DIY replicating what already exists).  And like I said, either we come up with something novel and legitimately capable of calling "breakthrough" or we give up.

... continued in next post ...
« Last Edit: May 09, 2016, 07:14:19 am by bootstrap »
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Offline bootstrapTopic starter

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Re: Pick and Place Discussion
« Reply #1 on: May 08, 2016, 08:58:21 am »


... continued from above ...

I definitely prefer DC servos for many reasons, but as long as the system is closed-loop somehow, steppers are an alternative.  Note that in the past I developed devices that had high-count encoders that I made by copying encoder disks onto super-high-resolution microfilm and building the encoders into the mechanics itself.  So I got around the expense of high-count encoders that way.  Not sure the tradeoffs are the same today, but perhaps.

However, my hope is, we can leverage relatively inexpensive cameras into replacing expensive linear encoders (or rotary encoders for that matter).  I did that on my mechanical version a couple years ago, and I'm fairly confident we can figure out ways to do the same (or analogous) with a device we design from scratch.  This WILL require we add new code path to OpenPnP if we adopt that (which I assume we would, though not necessary), but that's not such a big deal.  Incidentally, another fellow here and I already mentioned introductory ideas for how to replace expensive encoders and/or mechanics by means of [somewhat] novel application of cameras in the design.  Maybe that "other fellow" was you (not sure).

Let me just point out one opportunity that addresses the exact problem you mention in your message... the pick-up nozzle/nozzles doesn't come down precisely in the middle of the component.  Well, that can easily be solved with a down-looking camera plus a slight change in technique.  How so?

If the "downer camera" (forgive the invented term) attached to the moving nozzle/nozzles assembly is at a fixed and exactly known x,y distance from the pick-up nozzle/nozzles, (and mounted close to the pick-up nozzle/nozzles), then the machine can move the camera over the component first, find or note the exact position [and rotation] of the center of the component still in the tape (and for conceptual and visualization purposes, then move the exact center of the field directly over the center of the component), then the exact center of the nozzle can be moved over the exact center of the component simply by moving the nozzle assembly the exact x,y distance/distances we know it is from the nozzle/nozzles.  Problem solved... at the expense of speed, because we need to perform this extra step for every [small] component the machine needs to place.

But... what about precision of x,y motion that we will need?  Well, one answer is to do what I did before... create super-cheap 1~2 micron linear encoder scales on microfilm.  But, there is another way that also takes advantage of the characteristics of cameras.  For visual and conceptual purposes, assume the camera has no "field distortion" (meaning points on the PCB imaged 1000 and 2000 pixels from the exact center of the field have a linear relationship).  In other words, that point on the PCB that is imaged 2000 pixels from the exact center of the field is precisely twice as far away from the point on the PCB at field center as the point on the PCB that is imaged 1000 pixels from the exact center.  Hopefully you intuitively know what "field distortion" means so you don't need to untangle my extremely clumsy description!

BTW, this does not need to be true (we only need to know what the field distortion is for the camera and lens), but for visualization and conceptualization let's make this assumption.

My claim is, this can replace linear encoders with no loss of x,y position precision.  How so?  Well, to visualize and conceptualize the situation before I cut to the chase, assume we DO have linear scales on the machine, but instead of being inside mechanical housings along with LEDs, light sensors and quadrature masks, we just "glue" the scales to the x and y "rails" or shafts the nozzle assembly slides against as it moves in x and y.  Now imagine we have an "x-axis upper camera" and "y-axis upper camera" attached to the moving "nozzle/nozzles assembly" pointing at these linear scales that are fixed to the x and y "rails" or shafts.  If we slide the "nozzle/nozzles assembly" back and forth on the x and y "rails" or shafts and look at the images these cameras send to a display monitor, we will see the lines on the linear encoder scales move back and forth as the "nozzle/nozzles assembly" moves.  If we were truly demented (and the motion wasn't too fast for cameras), we could write software to count the scale lines that pass, and even perform quadrature encoding on appropriately separated pixels.

Now that's a rather stupid idea so far, because the LEDs, light sensors and quadrature masks will probably cost no more and be no more hassle than these two cameras.

BUT... notice this.  We don't need the linear scales at all !!!!!

How so?  Well, let's now assume we simply placed very narrow marks along those two x and y "rails" or shafts approximately (but not precisely) 4 inches apart.  There are much better ways to accomplish this than scratch or paint marks, but we'll ignore that practical issue.  Essentially what we've done is remove 3999 out of every 4000 marks on the scale, and leave one out of every 4000 marks alone.  Except unlike the linear encoder scales, the marks won't be exactly 4 inches apart, they'll be 4 inches plus or minus something like 0.0100" apart.  In other words, not at precise intervals (which means, easy and cheap to accomplish but not precisely spaced like the encoder scales).

So... what is this supposed to do for us?  Well, think about it.  Before one mark exits one end of our 4096 wide/high pixel image, the next mark appears on the other end of the image.  Now, let's say that even though the marks are not separated by precise distances, we nonetheless KNOW how far apart they are (measured after assembly and before we test the machine).  Since we now know the precise separation of those marks, and the 4096 pixels on the image have a fixed relationship to distance on the x and y "rails" or shafts, when we watch any mark move from camera pixel to camera pixel on the camera images on the monitor, we know precisely how far the "nozzle/nozzles assembly" has moved in x and y.  And since the next mark always appears in the camera images before the previous mark vanishes, we can ALWAYS keep track of the exact position of the "nozzle/nozzles assembly"!

In other words, once we know how many microns on the x and y "rails" or shafts corresponds to 4000 pixels on these two camera images, we can keep track of the exact position of the "nozzle/nozzles assembly" as it moves by reference to these camera images!

Essentially what we need to do is establish that relationship... how many microns on the x and y axes corresponds to 4000 pixels on the camera images.  We can do this in several ways, so I won't wear you out by mentioning the ways I've thought up so far.  Maybe you have even better ideas for this.

Do you see how that works?  We now have the precision of super-duper precise linear encoders for the price of two cheap cameras.  In other words, we have a fully closed-loop scheme.  While we might (in some versions) need a precise gig at the factory to establish the distances between the marks, nothing expensive needs to ship with each machine!

BTW, there are several tweaks on this principle, including the fact it might be cheaper, more lightweight and bulky, and easier mechanically if the sensors in those cameras are 1D sensors instead of 2D sensors.  In other words, they can be 4096 by 1 sensors instead of 4096 by 4096 sensors (or whatever).  The example I gave generates 0.001" AKA 25u (25 micron) resolution without quadrature tricks, and about 0.00025" AKA 6.25u resolution with quadrature and/or mark versus pixel estimation/interpolation.  Personally I'd prefer to shoot for 1u, 2u or 4u resolution (which requires the marks be closer together and/or more pixels on the sensor (perhaps 8192 or 16384 pixels if linear sensors).

The feeders are another area where we probably need to "think far outside the box" and invent some better scheme.  That may be made easier by the "downer camera" I described above, since the position of components no longer needs to be precisely located.  But hopefully we can do much better than that!  For sure we need some way to prevent feeders from increasing the cost of real systems very much.

I have at least one idea about that, but I'm sure there are many others.  Rather than wear you down now, we can discuss this idea in our next message if you want to continue with this brainstorming.  I'd like to support both desires in this topic.  You want to support boatloads of feeders without excessive cost, which we should support.  While other folks might be willing to change feeders after each part.  PS:  What I mean to suggest here is that the software places ALL instances of each component on the PCB, then beeps to tell the operator to install the next component reel.  Though actually there should probably be two reel positions instead of one, so it can move on to the next component reel while the operator changes the other position to load the subsequent component reel (a classic "pipeline" approach).

PS:  I don't like used equipment... too potentially problematic for me!  Plus, to place 0201 and smaller components, most non-current machines are not capable.

How much is my time worth?  Hahaha.  No idea (other than smart aleck responses).  I guess my answer is this.  I'm in a position to do this project if I want to (or just retire and live a frugal but comfortable life).  So the real answer may be annoying, but truly is "if it seems worthwhile" (in "coolness" and "potential" at the very least).  I am annoyed that so many aspects of the hardware development process have been taken over by huge corporations by means of "scurvy tricks".  This project would defeat one of those... assuming we develop a sufficiently novel, cost effective and capable device.

Your turn!

FYI, the first two PCBs have already are:  8-layers, 4-mil traces, 0201s, 0.50mm BGAs/QFNs.  One is 200mm square and the other 100mm square.  I figure they are fairly representative in character to others that will follow in the next 3 or 4 years (at least).
« Last Edit: May 09, 2016, 07:13:17 am by bootstrap »
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Offline glenenglish

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Re: Pick and Place Discussion
« Reply #2 on: May 08, 2016, 08:58:59 am »
This is not the right discussion for the NEODEN4 thread

this thread is for NEODEN4 owners, and aspiring owners to discuss specific associated items. This is not a PnP general discussion thread....
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Offline mrpackethead

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Re: Pick and Place Discussion
« Reply #3 on: May 08, 2016, 08:59:25 am »
Can i suggest you start another thread so you are not hijacking this one abut the N4.
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Offline bootstrapTopic starter

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Re: Pick and Place Discussion
« Reply #4 on: May 08, 2016, 09:14:44 am »
Quote from: mrpackethead on May 08, 2016, 08:59:25 am
Can i suggest you start another thread so you are not hijacking this one abut the N4.

Yes, I think that's appropriate.  Since I'm new here, and don't frequent forums very often, does anyone know what that involves (to bring along those existing posts that are relevant to this, perhaps without losing the author identities)?

What's an appropriate title?  "New PnP design ideas for an inexpensive, high precision, modest speed machine for developer prototypes and small batches"?

As an aside... who cares whether some people are hard-core skeptics?  Doesn't matter.  Of course, statistically speaking, they're usually right, especially in the context of forums.

PS:  Yeah, wouldn't want neoden getting any radically new ideas!
« Last Edit: May 09, 2016, 07:12:59 am by bootstrap »
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Offline Koen

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Re: Pick and Place Discussion
« Reply #5 on: May 08, 2016, 09:39:50 am »
This really is novel, brilliant and ground breaking. Any chance we'd get to see some of your previous work ?
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Offline bootstrapTopic starter

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Re: Pick and Place Discussion
« Reply #6 on: May 08, 2016, 09:47:02 am »
Quote from: Koen on May 08, 2016, 09:39:50 am
This really is novel, brilliant and ground breaking. Any chance we'd get to see some of your previous work ?

Hahaha.  You forgot "/sarcasm", right?  Note that spikee had what is essentially the same main idea independently, so really, being unconventional isn't so impossible.  If I do say so myself, I don't do projects unless I have at least a couple radically unique approaches (or the device/technology is totally unique).  But, I have to admit I really don't know whether you're being sarcastic or not, so forgive this comment if I fell into your trap.   :scared:

I also suspect a few creative people can come up with at least 2 or 3 more ideas (hopefully to solve feeder issues).

PS:  Maybe two or three of us with good ideas should offer to collaborate with neoden on the neoden6 model (based on these and subsequent ideas) in exchange for free units and a small royalty.
« Last Edit: May 09, 2016, 07:12:30 am by bootstrap »
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Offline Koen

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Re: Pick and Place Discussion
« Reply #7 on: May 08, 2016, 09:51:40 am »
No, I'm genuinely interested in the radically unique approaches of your previous projects.
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Offline mrpackethead

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Re: Pick and Place Discussion
« Reply #8 on: May 08, 2016, 10:24:06 am »
Feeder problems well solved, but you don't need our help.
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Offline mrpackethead

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Re: Pick and Place Discussion
« Reply #9 on: May 08, 2016, 10:26:30 am »
Quote from: bootstrap on May 08, 2016, 09:47:02 am
PS:  Maybe two or three of us with good ideas should offer to collaborate with neoden on the neoden6 model (based on these and subsequent ideas) in exchange for free units and a small royalty.
[/font]

Actually i'd like to Introduce you to Micheal Bruch, who is the co-owner of SmallSMT.  I think you go will hit it off fantastically.  Micheal goes by the name SmallSMT on this forum..   Hes into the same kind of things you are.
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Offline bootstrapTopic starter

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Re: Pick and Place Discussion
« Reply #10 on: May 08, 2016, 10:32:24 am »
Quote from: mrpackethead on May 08, 2016, 10:24:06 am
Feeder problems well solved, but you don't need our help.

Given I've never worked with pick-and-place (or stencil-printers, feeders, reflow-ovens), I wouldn't be so sure of that.  It often helps for people to explain the "problems" they have, or present their "wish lists" (even if as simple as "feeders are too damn expensive").  Though I have substantial experience with robotics and precision mechanical and optical systems, I haven't faced the practical frustrations of working with SMT equipment.
« Last Edit: May 08, 2016, 10:44:11 am by bootstrap »
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Offline bootstrapTopic starter

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Re: Pick and Place Discussion
« Reply #11 on: May 08, 2016, 10:41:42 am »
Quote from: Koen on May 08, 2016, 09:51:40 am
No, I'm genuinely interested in the radically unique approaches of your previous projects.

Previous projects... but not this one?  See, I'm still not sure whether you're being sarcastic or not.  Most of my projects have been in the fields of computer architecture, software techniques, optical systems (usually related to telescopes or instrumentation somehow) and advanced (smarter than human) inorganic consciousness.  I don't mind showing previous projects except... I've always been a very private hermit type, and don't like attention.

Here is one technology that may or may not mean anything to you.  NASA wanted to determine the 3D position of GEO satellites to much higher precision (with optical instruments, not radar and such).  They also had what they considered an "impossible wet dream" that they could determine the size, shape and orientation of those satellites from observations with ground telescopes.  Due mostly to atmospheric turbulence (and other factors), this was totally impossible, even with the biggest telescopes on the planet.  I invented a technique that let them determine the 3D position as well as the size, shape and orientation of satellites in GEO orbit to a precision of 50mm ~ 100mm with tiny telescopes (on the order of 200mm aperture).  Their PhDs swore this was impossible, but that's because they tend to think in conventional terms.  And indeed (being an optics expert myself), they were correct that conventional imaging could never achieve this.  Where I'm different is, I'm pretty good at thinking in very fundamental terms AND very comfortable searching for totally different (but usually simple) approaches that somehow "avoid the impossibilities".

Here is another totally trivial "technique" that's much too simple to call a "technology".  How can a cheapo microcontroller keep track of position from optical encoders when the microcontroller is dozens or hundreds of times too slow to read the encoder signals (A, B, I channels) before dozens or hundreds of encoder increments pass by (when the device they are attached to is moving fast)?  To be clear, the A, B, I signals are simply fed into inputs bits of general purpose I/O pins and not into counters or any other kind of internal logic, so the technique is 100% pure software.  The technique works entirely by the microcontroller reading the 8-bit I/O port that contains the A, B, I signals from two encoders per 8-bit I/O port (or up to 4 encoders if no I (index) channel is needed).

This is one of those "oh, man... this is simpler than drinking water" techniques... once you "see it".  The trick, of course, is thinking up these crazy techniques when nobody has before (I assume).  Can you figure this out?  I'll bet someone here does before I post the answer.  It really is simple, but does require a bit of "outside the box" thinking or perspective.

Another is a faster and superior memory management approach for CPUs that AMD almost adopted long, long ago in a galaxy not so far away.  It speeds up and simplifies simultaneous multi-task and/or multi-thread processing while greatly reducing the extent and complexity of circuitry on the CPU.  Can you guess the key idea in this one?  Very simple.

Frankly, most of my "great ideas" are fundamentally simple and/or straightforward once you comprehend them.  This is one reason I prefer not to study existing approaches and technologies [in detail if at all] before I try to solve known problems (or "impossibilities") on my own (without the biases and assumptions of conventional approaches).  Maybe I'm "simple minded" in some unusual way that works.  OTOH, I don't want to mislead... these advances are pretty much always within fields that I had much previous experience, so I did have context.  For example, I was designing my second or third "from scratch" CPU and was annoyed by various aspects of conventional memory management approaches when out of frustration I decided to look for "a better way"... and found one.

PS:  Now I'm getting myself into real trouble... for being even further off topic if not more.  Maybe someone can copy the appropriate messages to a new thread so we don't further pollute this neoden thread.
« Last Edit: May 09, 2016, 07:11:50 am by bootstrap »
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Offline bootstrapTopic starter

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Re: Pick and Place Discussion
« Reply #12 on: May 08, 2016, 11:00:51 pm »
Quote from: mrpackethead on May 08, 2016, 10:26:30 am
Quote from: bootstrap on May 08, 2016, 09:47:02 am
PS:  Maybe two or three of us with good ideas should offer to collaborate with neoden on the neoden6 model (based on these and subsequent ideas) in exchange for free units and a small royalty.
[/font]

Actually i'd like to Introduce you to Micheal Bruch, who is the co-owner of SmallSMT.  I think you go will hit it off fantastically.  Micheal goes by the name SmallSMT on this forum..   Hes into the same kind of things you are.

Sure.  Perhaps you should invite him to comment on the ideas people have been presented so far.  That might be a good way to get started.

Or if this forum supports private messages, perhaps have him send me one.  But first, tell me/us what you're thinking?  Do you think a better approach than starting a new open-hardware project (of some sort) is to work with an existing [open or proprietary] manufacturer?  Or just involve him as the manufacturing part of the process?

In case it isn't obvious yet, I'm not proprietary with most of my ideas, at least not in this field.  This is not my focus in life, I just need this technology to work on my overarching "ultimate" project, which has a few subsystems, two or three of which involve subprojects (including that high-performance robotics vision system camera I mentioned before).  Plus, I strongly support open-source, open-hardware, open-core, open-technology, so I'm happy to contribute ideas, projects and technologies when I can.

Finally, if one or more of you out there is interested in exploring and developing these ideas further, we could schedule a skype conference call and do some real time brainstorming.
« Last Edit: May 09, 2016, 07:11:27 am by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #13 on: May 09, 2016, 03:20:51 am »
Some recent messages in this topic, plus some straggler messages in the neoden4 topic these messages were extracted from, discussed ways that cheap cameras can perform some of the functionality of pick-and-place machines, and make the machines easier and/or cheaper to make.

I want to carry that idea further, and perhaps describe a technique close to the best approach.

To remind everyone what my goals are in this discussion, they are:

#1:  precision placement of small, medium and large parts with fine, medium, coarse pitch contacts.

#2:  inexpensive as possible, and hopefully something that can be built without exotic equipment.

#3:  can be slower than expensive commercial alternatives, but hopefully only 2 to 5 times slower.


What I describe here addresses the main pick-and-place machine, but only some aspects of the feeders.  The feeders are very important components of the pick-and-place machine in terms of cost and complexity, and will need further consideration later on.

-----

The basic idea is this:  cameras can look at various parts of the "workspace" and thereby replace some of the elements of conventional pick-and-place machines.

The "workspace" includes:

#1:  the PCB.
#2:  the nozzle tips.
#3:  components on the feeders.
#4:  components on the nozzles.
#5:  the x axis scale or reference marks (to measure x position).
#6:  the y axis scale or reference marks (to measure y position).
#7:  anything else that can help us increase functionality or speed.

Previous messages explained the following steps or facts in our provisional proposed pick-and-place process:

process A : pick up component from feeder (components in trays and other holders will be similar).

#A01:  The center pixel in the down-looking "nozzle camera" on the nozzle head is focused at a point on the PCB that is an exactly known x,y distance from where the exact center of the nozzle (or each nozzle if we choose to support 4+ nozzles) will touch the PCB when lowered.

#A02:  We have ways to establish the exact relationship of the "nozzle camera" image to the PCB surface.  In other words:  Assume the point on the PCB surface at the exact center of the image is 0,0 (offset in microns from point on PCB in center of image).  The software knows the precise x,y distance from 0,0 on the PCB that is imaged on each pixel of the nozzle camera image.

#A03:  We design the mechanics of the machine so the top of average small components in feeders is at the same height as the surface of the PCB.  The height of large components is not important because there is no possibility the pickup nozzle will come down off the edge of a large component (the machine can't be that imprecise).

#A04:  To pick up a small component from a feeder, first the "nozzle camera" moves over the expected location of the desired component and takes an exposure of that component.  If the component is offset in x or y, the camera moves slightly to center the component and takes another exposure to confirm (more likely software notes the x,y offset and factors that into the next step).

#A05:  The "nozzle head" then moves the known x,y distance between "nozzle camera" image center and nozzle tip center, which positions the center of the nozzle precisely over the middle of the component.

#A06:  The "nozzle head" lowers and picks up the component, which is exactly centered on the nozzle tip (no failed pickups).

The main purpose of the above process is to assure the nozzle does not come down slightly off center of tiny components, which can cause the component to tip over or the vacuum seal of the nozzle tip to the component to be insufficient to hold the part to the nozzle tip when the nozzle rises.  The precision we achieve by this process prevents failures to pick up tiny components, or failures to hold onto tiny components as the nozzle head accelerates and decelerates during subsequent steps.

Larger components can bypass this step because the precision of the machine is sufficient to assure the tip will come down near enough the center of the component that these kinds of failures cannot occur.

The component should now be picked up by the nozzle.

-----

Now let's continue with subsequent steps of the proposed pick-and-place process (some not addressed in previous messages).

process B : center component on nozzle then rotate to desired placement orientation.

We may or may not decide to implement this step depending on further consideration and tests.  We may also decide the perform this step on some but not all types of components (certain package types and/or sizes).

#B01:  The "align/center jaws" close on the component to center in x and align the component edges with the x,y axes.

#B02:  The "align/center jaws" open.

#B03:  The nozzle rotates 90 degrees.

#B04:  The "align/center jaws" close on the component to center in x and align the component edges with the x,y axes.

#B05:  The nozzle rotates to the angle the component must be placed on the PCB.

The component should now be exactly centered on the nozzle, and rotated to the appropriate angle.

-----

process C : determine exact position and angle of component on nozzle tip.

#C01:  move center of nozzle tip over center of up-looking "component camera".

#C02:  take exposure of component on nozzle tip with up-looking "component camera".

#C03:  if component not exactly centered or rotated properly, move and/or rotate nozzle to fix.

#C04:  take exposure of component on nozzle tip with up-looking "component camera".

#C05:  go to step #C03.

PS:  Note that the previous 3 steps are done based upon the contact pads or balls on the underside of the component for BGAs, QFNs and many other package types.  This may also be true for some or all discrete components, but some if not most discrete components could alternatively be centered based upon the outside of the package.

The center of the component is now directly over the center of the up-looking "component camera" and rotated to the orientation the component must be placed on the PCB.


-----

process D : center down-looking "nozzle camera" over exact point on PCB to place center of component on nozzle.

#D01:  move "nozzle head" in x,y to center down-looking "nozzle camera" over point on PCB where center of component on nozzle should be placed.

#D02:  take exposure with down-looking "nozzle camera".

#D03:  software finds and measures the positions of several "sync points" on the PCB near and surrounding the component to be placed.  The software knows the precise location of these pads and marks on the PCB relative to the point the component center must be placed from the gerber file and/or images of the PCB taken just before component placement process was started.  Therefore, the software can establish the exact point on the PCB image where the center of the component must be placed by offsets of where these "sync points" are in the image relative to where they should be when the component is precisely placed.  The software can also determine how much adjustment in component rotation is required to compensate for any [unexpected] rotation of the PCB axes relative to the machine axes (which should already have been known and compensated for, but can be double-checked here).

#D04:  move "nozzle head" slightly in x,y and rotate nozzle slightly in a to compensate for the offset and rotation errors found in the previous step.

#D05:  go to #D02.

Now the center of the image of the "nozzle camera" is precisely over the point on the PCB where the component center must be placed, and the component is rotated at precisely the desired orientation.

Note: we did something unconventional but very desirable above.  Other pick-and-place machines base their positions entirely on the basis of moving the "nozzle head" in x and y (which is done on the basis of stepper-motor steps or glass-scale increments).  True, they are based upon the original x,y positions of the two fiducial marks established ONCE before the PCB placement process began, but after those fiducial marks are observed, all subsequent positions are assumptions based upon presumed precise motions of the "nozzle head" along the x,y axes.

In our case, we determined the position the component center belongs by inspecting nearby features on the PCB surface immediately before the component is placed.  Any motion, rotation or bending of the PCB in its holder since the fiducial marks were scanned will not cause errors in our placement.  Also, any "missed steps" in stepper motors or "missed increments" in encoders will not cause errors in our placement.

In effect, by finding several key features near the component, we treat those key features as "local fiducial marks", and thereby determine placement position directly from the surface of the PCB.

Note that we cannot do this same process reliably by inspecting the pads of the component itself.  Why?  Because the solder paste may extend beyond those pads, and make their locations indeterminate by examination.  However, the pads around tiny through-holes and certain other features will not be covered by solder paste, so we can determine positions on the PCB from them (3 minimum).  We can even work off things like "pin 1 markers" as long as they are in the etched copper, not silkscreen.

-----

... continued in next message ...
« Last Edit: May 09, 2016, 07:11:03 am by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #14 on: May 09, 2016, 03:22:09 am »

... continued from previous message ...

-----

process E : center component over PCB.

#E01:  Move the "nozzle head" the known x,y distance between the tip of the nozzle and down-looking "nozzle camera".  Note from previous steps above that we precisely know this distance.

Now the center of the component is precisely over the point on the PCB where the component center must be placed, and the component is rotated at precisely the desired orientation.

-----

process F : place component on PCB.

#F01:  Lower the nozzle until component touches PCB.

#F02:  Switch nozzle from vacuum to positive pressure.

#F03:  Raise the nozzle and keep positive pressure to "blow" component off the nozzle tip.  While the natural adhesion of the solder paste may be sufficient to hold the component down when the nozzle tip rises, we cannot count on that.  The exact optimum timing for when the positive pressure should be applied, and with how much pressure, is presumably something to be learned from experience and tests (and probably varies with component package, component mass, etc).

Now the component is placed.


-----

#####  COMMENTS  #####

The above description still assumes we can move the "nozzle head" precise distances along the x,y axis.  While the approach we describe above only needs to be precise over relatively short distances (perhaps 100mm or so), it still needs to be as precise as any highly precise pick-and-place machine over those distances.

Previous messages described how we can essentially create the equivalent of very cheap but ultra-precise linear encoders with two up-looking cameras (one "x-axis camera" and one "y-axis camera").  We do not repeat those descriptions here.

Instead, here is an alternative that completely eliminates the need for highly-precise linear encoders, or highly-precise lead-screws, or highly-precise measurement of any kind!

The following does assume we can measure x,y position with moderate precision, but this precision is easily and cheaply achieved with rotary encoders on the shafts of the motors that drive the "nozzle head" along the x and y axes.

To prepare our brains to understand the following approach, we should remind ourselves of an important aspect of the processes described above, and how they are different from conventional pick-and-place machines in one crucial way.

#1:  At every key step we actually LOOK at the components and PCB to determine position.  We LOOK down at the component in the feeder (or tray or holder) with the down-looking "nozzle camera".  We LOOK up at the component on the nozzle tip with the up-looking "component camera".  We LOOK down at the key features on the PCB with the down-looking "nozzle camera".  In other words, our process is LOOKING AT REALITY and making its decisions based upon the actual components and actual PCB (and that's all we care about... to position the components on the PCB).

#2:  We only need ultra-precise x,y motion twice:

2A:  The first time is when we move the "nozzle head" to switch from "nozzle camera directly over component center" to "nozzle tip directly over component center".  That distance is a constant and known x,y distance, but it must be precise (actually, only fairly precise during this step, precise enough to reliably pick up the smallest components).

2B:  The second time is when we move the "nozzle head" to switch from "nozzle camera directly over desired component center point on PCB" to "nozzle tip with component attached directly over component center".  That distance is the same constant and known x,y distance as step #1.  But this time, the motion must be ultra-precise, so when the nozzle is lowered, the center of the component comes down precisely where the center of the component belongs on the PCB.

-----

Now that we have that fresh in mind, we might notice something.  The only times we need ultra-precise motion is when we move the "nozzle head" back and forth by the constant and known distance between the center of the nozzle tip and the center of the down-looking "nozzle camera" image.

But wait!!!  That is a constant distance!!!  Which means we don't even need to detect the thousands of intermediate increments between those two positions, because we always move the same distance.  All we need to detect are two specific positions for the "nozzle head" (or 4 positions if we have 3 nozzles and one "nozzle camera").

Let's assume for the moment we only have one nozzle, and we design the machine so the required ultra-precise motion is only along the x-axis.  That means we don't even need precise position measurement on the y-axis!

One axis down... and one to go!  :-)

But what do we really need on the x-axis?  Since the distance we move is always the same, why can't we just slide the "nozzle head" back and forth against hard, physical "limit stops"?  Then we don't need to measure anything, because the physical device itself determines the position.

Holy smokes!  Now we don't need ANY precision position measurement!


We still need ultra-precise motion, but that is handled by the physical nature of the "nozzle head slide".  So we have now totally eliminated the need for ultra-precise position measurement devices!  Yet we can still place components with ultra-precise accuracy.  Can't beat that with a stick!

But our "reliability engineer" raises his hand and asks a question.  Is this mechanical scheme 100% repeatable?  Maybe a flake of dust will float between those hard limits and stop the slide several microns short of the desired position.  Then what?

Three possible solutions.

#1:  We test and learn the limits have been designed in a way that the motion remains precise and repeatable [unless someone operates the machine in an environment vastly too dirty for pick-and-place work].  We note in our instructions that "our machine is not appropriate for operating in sand storms or next to milling machines throwing off metal chips"... or whatever.

#2:  We place LEDs and photo-transistors behind 1~4 micron slits (openings) at the desired separation on this "nozzle head slide".  Then when the "nozzle head" is moved from one limit stop to the other, the device aligns the two 1~4 micron slits so the position is detected before it considers the "nozzle head" moved.  Essentially we just created a super-precise linear encoder with only 2 increments.

#3:  We place a piece of clear glass in front of the "nozzle camera" lens and tilted at a ~45 degree angle.  This clear glass will reflect somewhere between 0.1% and 4% depending on what kind of optical coatings the glass has, if any.  This will produce a "ghost image" of whatever is at right angles from the direction this down-looking "nozzle camera" is pointing (and at the same distance from the lens as the PCB surface).  We then have the software watch marks or back-lit LED slits on the fixed x axis rail to measure x-axis position.

These basic approaches can also be applied to 3+ nozzles (with thought).

#####  IMPORTANT ALTERNATIVE TO CONSIDER  #####

This "constant and known distance" and motion can also be done in a different but analogous manner... an alternative to moving/sliding the "nozzle head" back and forth a constant and known distance (the distance between nozzle tip and "nozzle camera" image center).  This alternative might be better for many nozzle configurations (if we choose to support multiple nozzles, which I tend to resist for the first "model" or implementation).

In essence, we replace that constant, known, fixed linear motion with rotation.  Imagine the nozzle (or nozzles) are inserted into holes in a 10mm thick by 125mm diameter round metal disk.  By some means (physical/optical limits, encoder, etc) our software can rotate that disk precisely 180 degrees in either direction (or 90-degree steps for 3 nozzles and 1 "nozzle camera").  Assume the camera and nozzle are inserted into 20mm diameter holes in that disk at 50mm from the disk center (and precisely 180 across from each other).

We can now replace those "slide the nozzle head back and forth" steps with "rotate the nozzle disk 180 degrees" steps.

This has some obvious advantages (especially for multiple nozzle configurations), but also some disadvantages (probably mostly physical issues, like how wires and air/vacuum tubes to the nozzles move around while placing components).


#####  NOTES  #####

PS:  To see what "align/center jaws" look like (mentioned in process B above), see:


(see 06:00 ~ 06:30 in the above video).

  ... and ...


(see 00:40~00:50 and 03:20~03:30 in the above video).


#####  FINAL REMARKS  #####

I probably forgot to mention one or more assumptions and insights that the above depends upon, but you guys can grill me about any apparent flaws in the above and make me explain why everything above works properly.

I am fairly sure I have described a device that can place components very precisely, but doesn't contain any expensive components, and doesn't have to be massive (unless we try to crank up the speed too far).

However, I also assume we can make improvements on this approach and design.


#####  KEY ADVANCE  #####

If this approach has a "key advance", it is that we LOOK at the components and PCB with cameras to determine position.  This gave us ways to make our pick-and-place machine very precise without expensive parts like linear encoders.

However, this approach also has other inherent advantages.  For example, it inherently compensates for changes in the working environment during assembly, including:

#1:  PCB moves, rotates or expands/contracts due to temperature changes.
#2:  Parts of our machine flex, bend, shift or expand/contract due to temperature changes.
#3:  Our down-looking "nozzle camera" can determine whether components are placed or not.
#4:  Our up-looking "component camera" can determine exact position and rotation of components.
#5:  We take advantage of marks on the PCB surface near each component to determine component location.
#6:  The nozzles can pick up super-tiny components (always lowers the nozzle tip down exactly on their centers).


####################################

Your turn everyone.  Dive in... the waters are warm and friendly.
« Last Edit: May 09, 2016, 07:10:43 am by bootstrap »
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #15 on: May 09, 2016, 04:26:39 am »
Quote
"If this approach has a "key advance", it is that we LOOK at the components and PCB with cameras do determine position.  This gave us ways to make our pick-and-place machine very precise without expensive parts like linear encoders."

Lots of folks doing this with sub $1000 home build machines, made from sticks and bubblegum. ( almost litterally ).. So, not quite sure what key advance this is.

go to openpnp.org read all that, then go to the google grups and read all that..
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #16 on: May 09, 2016, 05:00:31 am »
Quote from: mrpackethead on May 09, 2016, 04:26:39 am
Quote
"If this approach has a "key advance", it is that we LOOK at the components and PCB with cameras to determine position.  This gave us ways to make our pick-and-place machine very precise without expensive parts like linear encoders."

Lots of folks doing this with sub $1000 home build machines, made from sticks and bubblegum (almost literally).  So, not quite sure what key advance this is.

Go to openpnp.org read all that, then go to the google groups and read all that..

Rather than just make unsupported assertions, wave your words around and ask me to spend thousands of hours inspecting (and understanding) a huge project, why don't you explain to me how sticks and bubble-gum can precisely place components as small as 0201 discretes and 0.30mm~0.50mm BGAs/QFNs on a PCB.

Just a few short paragraphs should be sufficient.

THEN, please explain to me why so many expensive commercial pick-and-place machines (and apparently every DIY pick-and-place machine) cannot reliably support 0201 discretes or 0.30mm to 0.50mm pitch BGAs/QFNs since all that's required is sticks and bubble-gum.

I mean, if sticks and bubble-gum is sufficient, why do companies spend so damn much time, effort and money to create their machines?

For that matter, why don't engineers place 0201s and 0.30mm pitch BGAs on their prototype PCBs by hand like before?  Who even needs sticks and bubble-gum?

BTW, you already know from past reading of these messages that we are specifically talking about a pick-and-place machines that DOES handle 0201 and 0.30mm to 0.50mm pitch components.  So please don't pretend AGAIN that this is not a requirement and the context, not to mention the entire reason for this topic.

PS:  I already looked at www.openpnp.org last night and followed the hardware links.
« Last Edit: May 09, 2016, 07:10:22 am by bootstrap »
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #17 on: May 09, 2016, 05:59:31 am »
Have you considered that your approach on this forum, might not be getting you the helpful responses that you might want.

If you took the time to read the posts, look at the pictures, you'll see there are people who have used low cost 3d printers, paperclips, rubberbands, Cheap web cams, bits of double sided tape, and all manner of other bits and peices to get remarkably accurate and useful results.  Theres people who have used the $350 Makerbot xy robot as a starting point..   These are everyone from students to hobbists, professional engineers, and people who also use Commerical machines, collectively i'm guessing with a lot of experience, and they have turned up at maker faires and the like so we know they are not just spouting this stuff off on the internet.

Vision processing is well down the track, and using things like opencv people are getting great results,  with both top and bottom cameras.
Theres some $40 nozzle adaptors you can buy, to connect to a $15 stepper..  and with a bit of microstepping magic, you can rotate those with the required accuracy to get 0201's down..     the small passives are not so hard..  Even a N4 can do it, with its open steppers and it less than nice feeders..   You jsut have to mess with it to do it well.     

Why dont' all the high end machiens support it.. Because in many cases they dont' have to..  There is'nt the high desnity pitch requirment..   And they are trying to hit targets in the 10's of thousands of parts p/hour..   Slow your machine down to 100's / hour and it gets much easier.

As a friendly suggestion, your coming across really aggresssive,  and that just never will work in these forums..    Many of the folks already have written you off as a phoney..  I'm not sure... but this is the internet so we just dont' ever know..


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Offline Bud

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Re: New Pick and Place design ideas
« Reply #18 on: May 09, 2016, 06:15:52 am »
Quote from: bootstrap on May 09, 2016, 05:00:31 am
font=Georgia  ...snip... /font

@bootstrap - can you not change font, your posts are hard to read
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #19 on: May 09, 2016, 07:08:32 am »
Reply to mrpackethead post above.

Have you considered that not everyone on this forum has the exact same interests or requirements as you?

Haven't you noticed all the people explaining how much difficulty they've had trying to place 0201 discretes and fine pitch components?  They TOTALLY CONTRADICT your claims that a pile of sticks, bubble-gum, paper-clips and rubber-bands can precisely place components.

So I guess not everyone is as brilliant and manually dexterous as you are, I suppose.  Certainly their machines aren't.

I don't know why you object to people having discussions about this topic.  OF COURSE not everyone will be interested in this topic, just like every other topic.  So what?  What's your gripe?  What's your problem?  If you want to place 0201 and 0.30mm pitch components with sticks and bubble-gum, that's okay with me (and I assume everyone else here too).  So why do you care how we do so?

I did microstepping decades ago.  Am I supposed to care about that?  The issue is NOT "how to move a small distance".  The issue is how to position precisely.  Just because a motor can turn a small distance does not mean the freaking component gets placed exactly where it belongs.  There are many pieces between the motor shaft and the component and PCB, and many assumptions and requirements too.  So you're just blowing smoke and making noise.

You say the neoden4 can place 0201s, and indeed they claim that.  However, some actual owners have said in this forum that it doesn't place them all reliably, which is a problem... though only if they want their PCBs to work.  And in case you have not noticed, the neoden4 isn't just a pile of sticks, bubblegum, rubber-bands and paperclips.

The expensive machines that cannot place tiny components do not fail because they are moving too fast.  How do I know?  Because they could slow down for problematic/tiny components if that was all they needed to place them precisely.

And companies aren't going to omit whole slews of components just so they can say they place 5%, 10% or even 20% faster.  It is more important that the machine can do the job than how fast it cannot do the job.

YOU are the one being aggressive.  And your "suggestion" is anything but friendly.  Calling it friendly doesn't make it friendly.  Furthermore, I don't give a damn whether 99.9% of the forum "writes me off".  I'm only interested in the 1, 2, 3 or 5 people who are interested in what I'm talking about (if they exist).  The others have other interests, which is fine with me, but apparently not with you.  The fact you don't know me or my abilities is irrelevant.  Anyone who cares about what I am discussing can judge from my posts whether I'm a total moron wannabe or not.  Sure, they can't know precisely, but they can make an estimate, just like I can make estimates about you from the content of your post.

BTW, I am not offended when people are more advanced than me in certain fields, or who have more sophisticated requirements than me, or etc.  That's totally natural.  I also don't look down on people less advanced than me or with less sophisticated requirements than me.  That's also totally natural.  But you appear to have a serious problem with me and my posts just because I need more precision than some or most people here, and want to discuss that with the 1, 2, 3, or 5 people who also need or care about that degree of precision (personally or at work).  My friendly suggestion is you focus on topics that match what your interests are.

Incidentally, I'm not sure what motive you might have for stopping a potentially worthwhile open-hardware project, one that I'd be spending tens of thousands of dollars of my own savings on (and who knows how many hours), and one that might benefit some folks in SMT land.  Maybe you can explain that.
« Last Edit: May 09, 2016, 11:23:13 am by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #20 on: May 09, 2016, 07:15:19 am »
Quote from: Bud on May 09, 2016, 06:15:52 am
Quote from: bootstrap on May 09, 2016, 05:00:31 am
font=Georgia  ...snip... /font

@bootstrap - can you not change font, your posts are hard to read

All my messages in this topic are now changed to the "verdana" font.

Hope that helps.
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Online forrestc

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Re: New Pick and Place design ideas
« Reply #21 on: May 09, 2016, 08:03:12 am »
Quote from: bootstrap on May 09, 2016, 07:08:32 am
I did microstepping decades ago.  Am I supposed to care about that?  The issue is NOT "how to move a small distance".  The issue is how to position precisely.  Just because a motor can turn a small distance does not mean the freaking component gets placed exactly where it belongs.  There are many pieces between the motor shaft and the component and PCB, and many assumptions and requirements too.  So you're just blowing smoke and making noise.

I think what you're missing is that he was talking about using opencv (aka machine vision) to place the parts accurately.   Once you have decent machine vision running, then you don't need all the expensive positioning feedback crap to make this work - but instead a decent vision system coupled with a less than stellar (aka cheap) positioning system.  And yes, that positioning system can be made out of whatever low-grade construction materials will work - and in this day and age it's not uncommon to see things like "a pile of sticks, bubble-gum, paper-clips and rubber-bands" as part of that.   I don't need an expensive stepper with a expensive belt and high quality position sensors.   I also don't need precision mechanics.  All I need is something which moves a camera and nozzle around to the general area of interest, provided the machine vision system can figure out where you are once you get there, and adjust accordingly.     So what if I've got nasty backlash, weird z axis warpage, etc?  Correct it with the feedback camera.

Of course, using high-end mechanical components will improve the accuracy of the placements - or I guess more accurately improve the accuracy of the initial machine placement before correction with machine vision. 
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #22 on: May 09, 2016, 10:05:56 am »
Point of attention, how do you visually recognize where you are exactly at the pcb without using fiducials or other markers with each and every component, which is a no go?
A clean pcb looks totally different from a pcb that was paste stencilled. The paste could be off a bit also.
And then each paste stencilled pcb will start to look different each and every 5 minutes you look at it, because the paste is oozing after its placed and also when it changes temperature.
Ofcourse when actually placing the components on the pcb, the visual aspect of that pcb will obviously also change. All those things can be pretty tough on the software to visually determine its exact position.

Quote from: bootstrap on May 08, 2016, 10:41:42 am
I've always been a very private hermit type, and don't like attention.
You could have fooled me. I think the advice from mrpackethead was not meant negatively but a relevant suggestion to succesfully socially interact on this forum.
The way you are communicating at this point seems to me more fit for a blog (one way direction).
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #23 on: May 09, 2016, 10:15:42 am »
Quote from: forrestc on May 09, 2016, 08:03:12 am
Quote from: bootstrap on May 09, 2016, 07:08:32 am
I did microstepping decades ago.  Am I supposed to care about that?  The issue is NOT "how to move a small distance".  The issue is how to position precisely.  Just because a motor can turn a small distance does not mean the freaking component gets placed exactly where it belongs.  There are many pieces between the motor shaft and the component and PCB, and many assumptions and requirements too.

I think what you're missing is that he was talking about using opencv (aka machine vision) to place the parts accurately.   Once you have decent machine vision running, then you don't need all the expensive positioning feedback crap to make this work - but instead a decent vision system coupled with a less than stellar (aka cheap) positioning system.  And yes, that positioning system can be made out of whatever low-grade construction materials will work - and in this day and age it's not uncommon to see things like "a pile of sticks, bubble-gum, paper-clips and rubber-bands" as part of that.   I don't need an expensive stepper with a expensive belt and high quality position sensors.   I also don't need precision mechanics.  All I need is something which moves a camera and nozzle around to the general area of interest, provided the machine vision system can figure out where you are once you get there, and adjust accordingly.     So what if I've got nasty backlash, weird z axis warpage, etc?  Correct it with the feedback camera.

Of course, using high-end mechanical components will improve the accuracy of the placements - or I guess more accurately improve the accuracy of the initial machine placement before correction with machine vision.

If you read my comments, then you should also know that I'm trying to avoid expensive mechanics in my design... and explicitly doing so with cameras AKA vision.  So I obviously have no gripe with that idea.  However, I haven't seen ANY of those who build DIY machines or ANY inexpensive pick-and-place machines that reliably place 0201 and 0.30mm~0.50mm pitch components.  That is, except neoden4 --- which is how I ended up in this forum and in the neoden4 topic.  While in the neoden4 topic at least one owner said the neoden4 places 0201 components, but not reliably (if I remember, 2 failures out of 100, which means many or most of my PCBs would be defective due to 0201 placement, even before including bad placement of fine-pitch components).

I wasn't aware openpnp requires steppers.  What I read about openpnp implied to me that the software was abstracted from the hardware to the extent possible so the software could run as wide a variety of machines as possible.  If openpnp doesn't require steppers, then I don't see how his comment about steppers has anything to do with openpnp.  Obviously steppers can drive a precise pick-and-place... IF the machine is closed-loop with precise sensors and/or the machine is awesomely precise.

You (and he) seem to imply that openpnp is magic software, that because it supports some kinds of "machine vision" means every pick-and-place machine it controls can place 0201 and 0.30mm pitch parts.  That is NOT what the owners of pick-and-place machines driven by openpnp claim, so I have to assume whatever "machine vision" support openpnp has, it is not sufficient to achieve that kind of placement precision on any and all wimpy, wobbly, imprecise, misaligned mechanics.  Again, that's what all the comments I've read imply.

If I'm wrong, and openpnp is "magic software" or "already incorporates and assumes the kinds of machine vision that I describe in my proposed scheme", someone should tell me so.  Nobody has explained how openpnp can achieve that precision, yet none of the actually built DIY machines do.

By the way, I don't recall reading anything on the openpnp webpages that I scanned that claims the approach openpnp takes and requires is inherently capable of placing 0201 and 0.30mm pitch components precisely, even on imprecise machines and backlash in the motion transmission scheme.  I didn't read every word, but I didn't see that claim anywhere, and I would have expected something like that right at the top in boldface!

How can the openpnp machine vision correct for all the machine defects you mention?  As far as I know, no configuration of machine vision cameras I've ever seen in a pick-and-place machine are sufficient to achieve that.

Which is the reason why I wrote my most recent double post to describe a specific configuration of machine vision to achieve the required precision with less than perfect mechanics.

One reason my brain is skeptical about these openpnp claims is because some of what I read about openpnp implies it tries to be general software that can be applied to pretty much any pick-and-place machine, especially those with conventional design.  Even conventional [commercial] designs that DO have machine vision (even 2-camera machine vision) are not able to place that precisely with crappy mechanics.  It was not my impression that openpnp is only designed for one specific design of pick-and-place machines.  Am I wrong?  I suppose I could have missed that statement somewhere.  Frankly, if openpnp is mainly/only for DIY machines, that would be a smart move.

Explain to me how the kind of machine vision you refer-to can assure the machine precisely places components.  Because I don't believe that, even when we play all the known tricks of the trade to compensate for backlash (always move the same x,y direction to anywhere important) or misaligned x,y axes and so forth.  I know at least most of these tricks/techniques well from a long time ago.

I assume you must have read the many, many, many, many, many comments about placement precision problems in the neoden4 topic and other pick-and-place topics.  Because I sure did!  Endless warnings about how much trouble those tiny components are, sometimes even on commercial machines that claim to fully support them with sufficient precision to be reliable.  And lots of very expensive machines WITH machine vision don't claim to support 0201 and 0.30mm~0.50mm pitch components.  Why would they not if it is so easy with appropriate software?  Is openpnp some kind of magic software or radical breakthrough or what?  I'm not trying to be a wise-ass with that question, either.  I ask because it sounds like that's what is being claimed.

Having designed, fabricated and worked with advanced diffraction limited optics for decades, I've worked with precision ranging from 0.0001" (mechanics) to 0.000001" (optical surfaces).  So I understand what these kinds of distances mean, and what is required to achieve them.  Even in devices without [fast] moving parts they're not trivial.  Here we're trying to work in the approximate range of 0.001" == 0.025mm == 25 microns or better, and we're doing so with all sorts of moving parts.  Now, if you read my post you see I'm a massive believer in solving the problem with "machine vision"... but only specific forms of machine vision that I've never seen on any pick-and-place I've seen in real machines.  And the "machine vision" approaches I have seen on pick-and-place machines are not sufficient to overcome the problems introduced by crappy mechanics.  I may be missing something, but I doubt it.  If I am missing something important, someone must explain what, because I don't see it, and I see all sorts of evidence to the contrary.

Please understand that I know people can place 0804 or 0603 and sometimes even 0402 components with conventional pick-and-place machines with conventional 1 or 2 camera vision systems.  Most that can even reach 0402 are very heavy machines with high-precision mechanics and rotary if not linear encoders, though some owners of these machines moan and groan at length on forums about reliability problems with the smallest supported components.

BTW, it really is a bit hilarious to me to see the current situation, which is:

#1:  Some people warn and complain about how many problems and difficulties exist with small components.

#2:  You two guys confidently claim "get openpnp and you can place any components with any precision you want with crappy mechanics made with sticks, bubblegum, paperclips and such".

I hope you can understand why that seems rather strange to me.

PS:  If you have an openpnp machine, I'll send you a pair of my PCBs from a few years ago complete with gerber files, BOM and the works.  Just place the 0201 caps (none of which are rotated), then take some close up photos and send them to me as proof.  Okay?  Oh, also send me detailed photos of your pick and place machine if they're placed correctly.  Unfortunately, they don't have very many 0201s... about 45 on the 150mm square PCB and 16 on the 70mm square PCB.

FYI, here are some photos of both sides of those PCBs so you have a general idea:

http://www.iceapps.com/ice_vision_pcb_6704.jpg
http://www.iceapps.com/ice_vision_pcb_6706.jpg
http://www.iceapps.com/ice_vision_pcb_6721.jpg
http://www.iceapps.com/ice_vision_bom_v0000a.pdf
« Last Edit: May 09, 2016, 11:39:09 am by bootstrap »
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Offline glenenglish

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Re: New Pick and Place design ideas
« Reply #24 on: May 09, 2016, 10:21:38 am »
Bootstrap if you don't change your attitude I doubt you will get any ideas across.

We're frankly not interested in your way of communicating.  Maybe we'll play some jokes on you, pretend to ask questions, annoy you a bit...

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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #25 on: May 09, 2016, 11:02:47 am »
Quote from: Kjelt on May 09, 2016, 10:05:56 am
Point of attention, how do you visually recognize where you are exactly at the pcb without using fiducials or other markers with each and every component, which is a no go?

#1:  I assume the PCB will have fiducials, and I assume every approach will take advantage of them.

#2:  If we need to, the first step would be to place an empty PCB without solderpaste or components into the machine and run a process that moves the down-looking "nozzle camera" over every component, then snaps a photo of that portion of the PCB (which might be the whole PCB for tiny PCBs).  This gives us images of every pad without solderpaste.  Alternatively and more conveniently the software can extract this information from the gerber file.
 
#3:  I have to assume even crappy mechanics will position the down-looking "nozzle camera" within... say... 0.01" == 0.25mm of any desired x,y position over the PCB (though not even that precision is necessary).

#4:  Unless the camera has an extraordinarily tiny field (which it won't and can't since some components are up to 2" == 50mm square), the image of each component will include quite a number of through-hole pads near and/or within the component area (and the component hasn't been placed, so any through-hole within the component are still visible).  Every one of those through-hole pads has a known x,y distance from the component center, and every component pad (from the images in step #2 and/or gerber file data).

Regarding camera field.  If the camera has a 4096 pixel sensor, and images a 4" square on the PCB, each pixel in the image corresponds to 0.001" == 0.025mm on the PCB surface.  With just a little image processing an effective resolution of twice that is not difficult (0.0005" == 0.012mm).  That should be sufficient, no?

#5:  I know my messages were excessively long, so I understand why you may have missed a phrase or two.  But I said we can't look at pads on the PCB that have solder-paste on them, for the reasons you stated.

#6:  If a PCB is extremely unusual, and some component has less than 3 visible through-hole pads within the 4" by 4" square centered on a component, then we'll have to insist that the PCB contain 1 or more "local fiducials" or [pointless] through-hole pads.  I think that will be extremely rare, if not "never".

Do you still see a problem?

Quote
A clean pcb looks totally different from a pcb that was paste stenciled.  The paste could be off a bit also.  And then each paste stenciled PCB will start to look different each and every 5 minutes you look at it, because the paste is oozing after its placed and also when it changes temperature.  Of course when actually placing the components on the PCB, the visual aspect of that PCB will obviously also change.  All those things can be pretty tough on the software to visually determine its exact position.

This is partially answered in #5 above.  To complete the answer, the position of the component pads is determined relative to through-hole pads, which are never covered by solder-paste.  At least I've never seen that happen.  Therefore, the fact that every time a component is placed the PCB looks different doesn't matter.  The software is only finding and looking at the through-hole pads (and treating them like "local fiducials" in a manner of speaking) to determine the position of the component center via the down-looking "nozzle camera".  Since the software knows where those through-hole pads are, it will have no trouble finding them (differences in the appearances elsewhere on the PCB are not even noticed).

Do you agree?

Quote
Quote from: bootstrap on May 08, 2016, 10:41:42 am
I've always been a very private hermit type, and don't like attention.
You could have fooled me.  I think the advice from mrpackethead was not meant negatively but a relevant suggestion to successfully socially interact on this forum.  The way you are communicating at this point seems to me more fit for a blog (one way direction).

You mean I should give so little information in my posts that nobody has enough information to understand or comment upon the issues and proposed approach (or make at least a vague judgement about whether I have any brains or experience or capabilities)?

Hey, I am quite certain my forum messages are vastly longer and vastly more detailed than most messages.  I don't have a blog, and don't publish anything.  Maybe my messages are "different" because I don't take on trivial (thus simple and short) topics or projects, or maybe because I'm someone who spends [tens/hundreds of] thousands on my projects, as well as months or years.  That kind of seriousness requires more time, care, effort and characters... at least for my lame little brain.

I can assure you I have ONLY been trying to be informative, honorable and helpful... and doing a project that might help a lot of people in the future if I decide to take it on.  From my perspective, it is just a few others who are being rude, snide, non-serious and obstructive.  However, with my tendency to be a non-social hermit, and as someone who is vastly more serious about my work than most people, I accept that people somehow manage to INFER a tone or attitude they don't like.  Nothing I can do about that.  My brain is focused on the technical issues when I write.  I'm not here for social purposes, I'm here for technical purposes, with the intent to take specific actions (buy a neoden4, a LE40V, or build a pick-and-place machine).  My guess is, anyone seriously interested in what I'm discussing for practical purpose and not just to talk or socialize would also be sufficiently focused on the content of the messages than whatever accidental aspect of my communication, language or approach annoys a few people.
« Last Edit: May 09, 2016, 01:28:01 pm by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #26 on: May 09, 2016, 11:09:05 am »
Quote from: glenenglish on May 09, 2016, 10:21:38 am
Bootstrap if you don't change your attitude I doubt you will get any ideas across.

We're frankly not interested in your way of communicating.  Maybe we'll play some jokes on you, pretend to ask questions, annoy you a bit...

And you complain about me?  !!!!!  WOW  !!!!!

And I'm frankly not interested in anyone who has no interest in posting messages with relevant technical content.  Maybe you should find some non-technical forums to attempt to socialize in, or just stick to communicating with folks who write in ways (and about topics) that appeal to you.

BTW, just about the most trivial and childish behavior I can imagine is playing jokes on (and trying to waste the time of) people trying to have a serious technical conversation.  I'm perfectly confident that my attitude and communication is vastly more appropriate than my detractors, no matter what oh-so-special social skills I may happen to lack IYNVHO.
« Last Edit: May 09, 2016, 11:41:32 am by bootstrap »
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #27 on: May 09, 2016, 11:48:55 am »
Quote from: bootstrap on May 09, 2016, 11:02:47 am
#1:  I assume the PCB will have fiducials, and I assume every approach will take advantage of them.
Yes ofcourse there are a few fiducials but are two enough to keep the exact location, say we have a 100x160mm pcb having two fiducials will not guarantee your exact location without other than visual guidance. So I guess , see below, we need more unique marking points on the pcb to keep the exact placement.

Quote
#2:  If we need to, the first step would be to place an empty PCB without solderpaste or components into the machine and run a process that moves the down-looking "nozzle camera" over every component, then snaps a photo of that portion of the PCB (which might be the whole PCB for tiny PCBs). 
That would take quite some time, that is why it is not done on pro placers I guess, those are all about time, but it could be a viable alternative for your proposed solution.

Quote
#4:  Unless the camera has an extraordinarily tiny field (which it won't and can't since some components are up to 2" == 50mm square), the image of each component will include quite a number through-hole pads near and/or within the component area (and the component hasn't been placed, so any through-hole within the component are still visible).  Every one of those through-hole pads has a known x,y distance from the component center, and every component pad (from the images in step #2 and/or gerber file data).
My (unscientific) gut feeling tells me you might need two camera's. One for the tiniest components having a tiny field of view but extremely precise , that could than also be used for the larger components to make the final placements adjustments, and one camera with a wider field of view for the bigger components to allow exact position of the entire component relative to the surrounding.

Quote
Regarding camera field.  If the camera has a 4096 pixel sensor, and images a 4" square on the PCB, each pixel in the image corresponds to 0.001" == 0.025mm on the PCB surface.  With just a little image processing an effective resolution of twice that is not difficult (0.0005" == 0.012mm).  That should be sufficient, no?
I think that would do be enough yes.

Quote
#6:  If a PCB is extremely unusual, and some component has less than 3 visible through-hole pads within the 4" by 4" square centered on a component, then we'll have to insist that the PCB contain 1 or more "local fiducials" or [pointless] through-hole pads.  I think that will be extremely rare, if not "never".
Instead of the through hole pads I would suggest using the via's, those are more common on smd pcb's.  But my guess is you meant the via's in the first place ?

Quote
Since the software knows where those through-hole pads are, it will have no trouble finding them (differences in the appearances elsewhere on the PCB are not even noticed).
Do you agree?
I do not know for sure if the via's are in the pnp file but they should be in order to get the needed accuracy for visual placement. A lot of smd pcb's nowadays do not have any TH components or only in small areas like the power supply.

Quote
Do you still see a problem?[/font]
If the via's are in the pnp file or can become part of the pnp file this could work. It will be slower and less for production suited but for small batches for hobbieists it would be an interesting alternative IMO.
Only the amount of time for the software development will be huge, I have no clue how long and how many programmers worked on openPNP but it must be a larger team effort to be succesfull.


Quote
I can assure you I have ONLY been trying to be informative, honorable and helpful... and doing a project that might help a lot of people in the future if I decide to take it on.  From my perspective, it is just a few others who are being rude, snide, non-serious and obstructive.  However, with my tendency to be a non-social hermit, and as someone who is vastly more serious about my work than most people, I accept that people somehow manage to INFER a tone or attitude they don't like.  Nothing I can do about that.  My brain is focused on the technical issues when I write.  I'm not here for social purposes, I'm here for technical purposes, with the intent to take specific actions (buy a neoden4, a LE40V, or build a pick-and-place machine).  My guess is, anyone seriously interested in what I'm discussing for practical purpose and not just to talk or socialize would also be sufficiently focused on the content of the messages than whatever accidental aspect of my communication, language or approach that annoys a few people.[/font]
I had a friend who taught me electronics when I was a kid who had a similar attitude, most only tech talk not much into social talk.
I can deal with it but also know the amount of problems, frustration and pain he had interacting with the outside world.
In his case it was not an option, it was how he was, if that is the same for you and you act like you always act I think we can only respect you for being open about it, and "are who you are".
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #28 on: May 09, 2016, 12:12:41 pm »
Reply to Kjelt.

Yeah, I started designing electronics and laying out PCBs decades ago when I was rather young.  Back then I never read or heard the world "via"... they were always called "through-holes".  So I got in the habit of saying "through-hole" and that stuck even after I started encountering the synonym "via".  I'll try to remember to say and write "via" instead of "through-hole" in the future, which will also shorten my messages a bit (hurray).

To perform a one-time scan of an unpopulated PCB will take much less time than placing components on that PCB.  So that overhead doesn't bother me.  Nonetheless, I believe the gerber files contain all that information.

Yes, the two or three standard fiducials on a medium or large PCB are very insufficient for precise placement of components.  That's why the via pads are necessary to act as "local fiducials".

The gerber files my PCB layout program (diptrace) generates contain locations of ALL holes (vias and holes for components with pins or leads).  In fact, the PCB manufacturers couldn't drill the PCBs without those locations, unless I'm missing something.  Plus they need the sizes of vias specified, otherwise they'd have to guess, which I don't think anyone wants!

I hope we don't need two down-looking "nozzle cameras".  But per my example, we won't be able to suffice with a low-resolution webcam type camera.  These days image sensors up to about 20 megapixels (5Kx4K) are quite inexpensive.

Yes, part of my design premise is, this machine can be up to 2x to 5x slower than commercial pick-and-place machines if necessary.  And I expect it will be about 2x to 3x slower.  I intend this to be open-hardware and probably openpnp (probably with some additions we'll have to write).  Nonetheless, what I'd call "my target market" in that context are individual engineers or engineers at nano-companies who only make prototypes or demos.  So if the placement process takes 2x or 5x as long but works reliably with 0201s and 0.30mm pitch, I'm happy.

If we can't just add to the openpnp code, then yeah, I suspect software development time will be substantial.  But since openpnp is open-source (I think), adding to openpnp should cut the workload substantially (I hope).  I'm a good, fast, quality programmer (assuming C or assembly-language (or C++ that isn't excessively strange)).  But if I'm lucky someone else will write the software!   :phew:

Yes, I am who I am, and I don't really give a damn what people think of me.  And I am indeed an extreme outlier... in many respects, actually.  At the same time, I'm the most benevolent human I know.  So go figure how those aspects of my personality fit together and coexist.  I rarely have problems with the "outside world", maybe because I rarely interact with the outside world, and I'm "live and let live".  Maybe your friend got frustrated because he cared what others think of him.  Unfortunate, that.
« Last Edit: May 09, 2016, 12:41:59 pm by bootstrap »
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #29 on: May 09, 2016, 12:24:13 pm »
Quote from: bootstrap on May 09, 2016, 12:12:41 pm
Yes, the two or three standard fiducials on a medium or large PCB are very insufficient for precise placement of components.  That's why the via pads are necessary to act as "local fiducials".
The gerber files my PCB layout program (diptrace) generates have locations of ALL holes (vias and holes for components with pins or leads).  In fact, the PCB manufacturers couldn't drill the PCBs without those locations, unless I'm missing something.  Plus they need the sizes of vias specified, otherwise they'd have to guess, which I don't think anyone wants!
Ah yes indeed you could use the drill files as input for the visual placement location, clever.
With some easy post processing you can determine also if the created pcb has enough unique of these location identifiers (I perse do not use the term fiducial since that is reserved for the two unique standard location identifiers) and if not create some extra. Although the pcb house might complain if there are small holes in the pcb without traces  :)
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #30 on: May 09, 2016, 12:28:01 pm »
Unfortunately, unless you have a via hole through a pad, it won't end up in the gerber files!  Oops!

How do you like the term "viaducial"?   :-DD   Okay, not that funny!

I like the term "local fiducial" for actual (but possibly/hopefully smaller) fiducial marks that aren't the primary fiducials.
« Last Edit: May 10, 2016, 08:13:15 am by bootstrap »
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #31 on: May 09, 2016, 12:39:45 pm »
Quote
Therefore, the fact that every time a component is placed the PCB looks different doesn't matter.  The software is only finding and looking at the through-hole pads (and treating them like "local fiducials" in a manner of speaking) to determine the position of the component center via the down-looking "nozzle camera".  Since the software knows where those through-hole pads are, it will have no trouble finding them (differences in the appearances elsewhere on the PCB are not even noticed).
Vias are normally covered in resist, so you  won't be able to reliably vision them
Hole positions can have small offsets from the copper , which is why they're not used for positioning   
Any system that relies on additional design features like vias as fids will have limitations - if you're using  0201's, you'll be short on space and won't want to be adding extra marks if there aren't already enough vias.

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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #32 on: May 09, 2016, 12:47:25 pm »
Quote from: mikeselectricstuff on May 09, 2016, 12:39:45 pm
Quote
Therefore, the fact that every time a component is placed the PCB looks different doesn't matter.  The software is only finding and looking at the through-hole pads (and treating them like "local fiducials" in a manner of speaking) to determine the position of the component center via the down-looking "nozzle camera".  Since the software knows where those through-hole pads are, it will have no trouble finding them (differences in the appearances elsewhere on the PCB are not even noticed).
Vias are normally covered in resist, so you  won't be able to reliably vision them.

Hole positions can have small offsets from the copper, which is why they're not used for positioning   
Any system that relies on additional design features like vias as fids will have limitations - if you're using  0201's, you'll be short on space and won't want to be adding extra marks if there aren't already enough vias.

I've never seen vias covered by soldermask.  My PCBs aren't that way.  Take a look at the images of two of my PCBs several messages back for examples (near bottom of page 1).

It may be possible to see via pads covered by resist.

If you look at the two PCBs a few messages back, you'll see that the traces are easily visible on the large PCB with medium-to-dark blue soldermask (which I assume you call "resist"... another term I should probably adopt, eh?).

The smaller PCB has a dark black soldermask because the IC in the center is an image sensor, and the idea is to prevent reflected and scattered light as much as possible.  Nonetheless, the traces are barely visible in the photos (easier with human eyes), so via pads might be visible to the camera even then.

If you're right, people will either leave [some] vias uncovered, or not apply a deep dark "resist".

It is absolutely necessary to work off the outside dimension of the pad around the via hole, not the hole itself.
« Last Edit: May 09, 2016, 12:59:20 pm by bootstrap »
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #33 on: May 09, 2016, 01:08:45 pm »
Quote from: bootstrap on May 09, 2016, 12:47:25 pm
Quote from: mikeselectricstuff on May 09, 2016, 12:39:45 pm
Quote
Therefore, the fact that every time a component is placed the PCB looks different doesn't matter.  The software is only finding and looking at the through-hole pads (and treating them like "local fiducials" in a manner of speaking) to determine the position of the component center via the down-looking "nozzle camera".  Since the software knows where those through-hole pads are, it will have no trouble finding them (differences in the appearances elsewhere on the PCB are not even noticed).
Vias are normally covered in resist, so you  won't be able to reliably vision them.

Hole positions can have small offsets from the copper, which is why they're not used for positioning   
Any system that relies on additional design features like vias as fids will have limitations - if you're using  0201's, you'll be short on space and won't want to be adding extra marks if there aren't already enough vias.

I've never seen vias covered by soldermask.  My PCBs aren't that way.  Take a look at the images of two of my PCBs several messages back for examples (near bottom of page 1).
Then you clearly haven't seen many PCBs.
Quote
It may be possible to see via pads covered by resist.
Not on a black or white resist.


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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #34 on: May 09, 2016, 01:21:21 pm »
Quote from: mikeselectricstuff on May 09, 2016, 01:08:45 pm
Quote from: bootstrap on May 09, 2016, 12:47:25 pm
Quote from: mikeselectricstuff on May 09, 2016, 12:39:45 pm
Quote
Therefore, the fact that every time a component is placed the PCB looks different doesn't matter.  The software is only finding and looking at the through-hole pads (and treating them like "local fiducials" in a manner of speaking) to determine the position of the component center via the down-looking "nozzle camera".  Since the software knows where those through-hole pads are, it will have no trouble finding them (differences in the appearances elsewhere on the PCB are not even noticed).
Vias are normally covered in resist, so you  won't be able to reliably vision them.

Hole positions can have small offsets from the copper, which is why they're not used for positioning   
Any system that relies on additional design features like vias as fids will have limitations - if you're using  0201's, you'll be short on space and won't want to be adding extra marks if there aren't already enough vias.

I've never seen vias covered by soldermask.  My PCBs aren't that way.  Take a look at the images of two of my PCBs several messages back for examples (near bottom of page 1).
Then you clearly haven't seen many PCBs.
Quote
It may be possible to see via pads covered by resist.
Not on a black or white resist.

I've seen thousands of PCBs, and designed dozens.  That doesn't mean I'd necessarily notice whether vias were covered with resist on other PCBs in some cases though.  I just poked around on the web and found that the vias are indeed covered by resist on some PCBs.  Hadn't noticed before.

I do know the default setting for my PCB software has been for resist to NOT cover vias.

I suspect white resist might be even more difficult than black, but I don't have any white PCBs here at the moment to look at.  I can see traces on my PCBs with black resist, but admittedly it isn't very easy, and might not be feasible for most cameras.

I don't consider it unreasonable to ask PCB designers to leave [some] vias uncovered (or not choose black or white resist).  That's not much of a price to pay to save boatloads on your pick-and-place machine, IMO.
« Last Edit: May 09, 2016, 01:38:26 pm by bootstrap »
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #35 on: May 09, 2016, 01:41:25 pm »
Quote from: bootstrap on May 09, 2016, 01:21:21 pm

I don't consider it unreasonable to ask PCB designers to leave [some] vias uncovered (or not choose black or white resist).  That's not much of a price to pay to save boatloads on your pick-and-place machine IMO.
I'd agree that leaving (some) vias uncovered would be a reasonable compromise, provided the system isn't going to need vias so close or so numerous that they need to be added specifically for the vision stuff to work.

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Offline Spikee

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Re: New Pick and Place design ideas
« Reply #36 on: May 09, 2016, 01:49:16 pm »
Placing 0201 / small qfn's or even bga is possible with my liteplacer which cost me 1000 euro. The problem is placing 5/10/100/1000 fully automated.
And yes I have placed bga's and or qfns with it. On my latest board I even placed bga's by hand so it is actually not that hard.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #37 on: May 09, 2016, 01:55:58 pm »
Quote from: mikeselectricstuff on May 09, 2016, 01:41:25 pm
Quote from: bootstrap on May 09, 2016, 01:21:21 pm

I don't consider it unreasonable to ask PCB designers to leave [some] vias uncovered (or not choose black or white resist).  That's not much of a price to pay to save boatloads on your pick-and-place machine IMO.
I'd agree that leaving (some) vias uncovered would be a reasonable compromise, provided the system isn't going to need vias so close or so numerous that they need to be added specifically for the vision stuff to work.

Based on the nominal design, the software would need at least visible 3 via pads in the 4" square around the center of every component.  Plus, at least 2 of the via pads must not be too terribly close together.  Actually it works with only 2 visible via pads, but prudence dictates "always have one extra".  Actually, with a bit more cleverness in the software, it should work with one via pad (though that's going further than my comfort level).

The process is possible with only 2 or 1 via pad because the software knows how much the x,y coordinate system of the PCB is tilted relative to the pick-and-place x,y axes from looking at several other components (not to mention the primary fiducial marks, which are generally separated the most, and thus give the best leverage for that computation).  Nonetheless, I'll continue to remember we need 3 to be safe.

In worst case scenarios there are other options, but they are not "nice".  For example, it is almost certain that solder paste will not flow beyond all four edges of any of the component pads (much less all the component pads).  So with some work, software should be able to find some straight edges on pads, and by that means determine the x or y location of those pad edges.  Of course, if the pads are round, that's a tad more difficult, but not impossible.

But I still would rather not "go there".
« Last Edit: May 10, 2016, 11:09:32 am by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #38 on: May 09, 2016, 02:04:22 pm »
Quote from: Spikee on May 09, 2016, 01:49:16 pm
Placing 0201 / small qfn's or even bga is possible with my liteplacer which cost me 1000 euro.  The problem is placing 5/10/100/1000 fully automated.

And yes I have placed bga's and or qfns with it.  On my latest board I even placed bga's by hand so it is actually not that hard.

Can you elaborate?  Are you saying your machine can place 5, 10, 100, 1000 components of 0201 size precisely enough, but "not automatically"?  Or you mean something else?  Have you done something special with your machine or process, or you think everyone who buys one of those machines can place 0201s and 0.30mm ~ 0.50mm pitch components reliably?  I was under the impression they didn't claim to support 0201s or such fine pitch components, but I'll go check again to see if my crappy memory is lying to me.

Also, I am only concerned about placing BGAs/QFNs and other fine pitch components when their pitch is 0.30mm to 0.50mm.  I believe you hand placed 1.00mm pitch BGAs, but find it difficult to believe 0.50mm pitch, and definitely not 0.30mm pitch (unless you are one lucky SOB, or the most talented guy on the planet).  I tried to place 0.50mm BGAs under an excellent stereo microscope but had to give up.

Another difference might be, most of my PCBs are not "tiny" and typically contain 300~500 components.  I know my PCBs are bigger and contain more components than many PCBs, but mine are not that far outside the norm.  So my target is to support large PCBs with hundreds of components.  PS:  When I say "large", I mean roughly 12" x 16" or larger.

The price certainly is right!

Later:  Some people in their forum have problems with 0201s (not pickup, but placement precision).  However, as you point out in their forum, they may be able to add code to support their up-looking camera like neoden4 to improve their precision.

The precision of 4 out of 5 of the 0603 components in their video are fairly bad.  Yet all but one of the 0402 components were placed better than the 0402s!  I infer a consistency issue, perhaps.

I see, no feeders.  For some people I think that's a smart way to go --- keep it cheap.  But for my purposes feeders are probably almost a requirement.  Nonetheless, I very much like the idea of making the machine capable of working without feeders, because some people only make tiny PCBs with not so many components.
« Last Edit: May 09, 2016, 02:32:30 pm by bootstrap »
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Offline Spikee

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Re: New Pick and Place design ideas
« Reply #39 on: May 09, 2016, 02:32:52 pm »
Placing a few of one small component is usually not that hard, doing many automated is. But that really depends on how good the software is and if the people that wrote it actually understand the vision algorithms.

With those super small smd parts the pickup nozzle is also quite important.
On my machine I have only changed the camera's (stock one's really suck), leds and pickup nozzle.
I have done a few bga's and 0402 passives not 0201.

0.5 mm bga is actually not that hard to place. Just put the silkscreen line at the exact size of the part. That way it is easy to put it on the right spot.

0.5qfn and the likes (especially with big center gnd pad) can do decent self alignement. As long as the placement is not that far off.

When I place a qfn / bga with my liteplacer I do this:
1. cal via fiducials
2. goto component tray
3. center on middle of ic via vision , pick up
4. do rotational offset
5. goto location and place

This could be fully auto but the software does not support this yet.

0201 imperial is small but not super small. If you use IPC complaint footprint for the passive than there is quite some margin for error. Passives re-align quite good.

If you have time than do the alignement for each placement. If you do not have time than do it every 5 placements for example.

Doing it fully mechanical (and automated) is quite expensive

A machine like the neoden 4 should be able to place it (I have not used one). But that kinda depends on how good it is made.

Regarding feeders, if the cam just looks (and calculates offset) before picking up the part than there should not be an issue.

btw. If your boards are that large in dimension why bother with 0201 imperial?

The limiting factor I currently have is that somewhat affordable pcb services use quite big minimum via sizes. Unless you pay a lot of money and go for laser drilling.

My latest design contained about 270 components for a 80x100mm size so your component count is mid to high qty.

Whatever machine you end up using I advice you to do a few test runs of you board on one of their machines. To see if it actually works for your application.

It will take some more time until the open source and somewhat affordable commercial software is ready for decent vision implementation. When that is done a relatively cheap machine can do the components you talk about.

At this time it is not there yet. Doing it the commercial route at this time will probably cost you 60+ k for the pnp from one of the bigger mfg's.
« Last Edit: May 09, 2016, 02:49:50 pm by Spikee »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #40 on: May 09, 2016, 02:55:39 pm »
Quote from: Spikee on May 09, 2016, 02:32:52 pm
0.5 mm bga is actually not that hard to place. Just put the silkscreen line at the exact size of the part. That way it is easy to put it on the right spot.

0.5qfn and the likes (especially with big center gnd pad) can do decent self alignement. As log as the placement is not super far off.

When I place a qfn / bga with my liteplacer I do this:
1. cal via fiducials
2. goto component tray
3. center on middle of ic via vision , pick up
4. do rotational offset
5. goto location and place

This could be fully auto but the software does not support this yet.

0201 imperial is small but not super small. If you use IPC complaint footprint for the passive than there is quite some margin for error. Passives re-align quite good.

If you have time than do the alignement for each placement. If you do not have time than do it every 5 placements for example.

Doing it fully mechanical (and automated) is quite expensive

A machine like the neoden 4 should be able to place it (I have not used one). But that kinda depends on how good it is made.

Regarding feeders, if the cam just looks (and calculates offset) before picking up the part than there should not be an issue.

btw. If your boards are that large in dimension why bother with 0201 imperial?

The limiting factor I currently have is that somewhat affordable pcb services use quite big minimum via sizes. Unless you pay a lot of money and go for laser drilling.

My latest design contained about 270 components for a 80x100mm size so your component count is mid to high qty.

Whatever machine you end up using I advice you to do a few test runs of you board on one of their machines. To see if it actually works for your application.

This is interesting, and the price is sooooo very "right" that I'm moderately impressed.

Just setting a 0.50mm QFN down at the correct position without smearing solder paste seems like a super-human feat to me!  The BGA is easier because maybe you don't necessarily need solder paste, so you can push it around while it is on the PCB.

From the neoden4 topic in this forum, it seems the neoden4 places about 98% of 0201 components precisely enough to work.  Unfortunately, a 2% error rate is too poor for my purposes.  If you look at the 150mm square PCB posted in my message near the bottom of page 1 of this topic, you'll see it contains about 50 of the 0201 components, and absolute boatloads of 0402 components.  A 2% error rate would mean most of my PCBs would fail due to bad 0201 placement... far too high!

I agree that placing 0201s and 0.50mm pitch fully mechanically and automatically is difficult... which is one reason machines that can do that are so expensive.  This is also why my approach is also vision based, albeit somewhat different.

BTW, it sure appears like the pads on their PCBs for 0201, 0402, 0603, 0805 components are significantly larger than the pads others (including me) put on the PCB for those size components.  While that definitely makes the placement process less difficult (less precise position requirement), that also somewhat defeats the purpose of tiny packages.  In fact, in most cases where I have 0201 components, they span from pad to pad under BGA components.  You can see that clearly in the 150mm square PCB I mentioned above.  The problem is, those pads cannot be made as big as they would be on their test board (assuming the follow the pattern established for the other sizes).

My current PCBs aren't that large, typically 3" to 8" square (or rectangular).  But at least two of my planned PCBs will be considerably larger (probably about 10" x 12" or 12" by 16").  Not as large as most of the PCBs I used to make in the "old days", which were typically 12" x 16 to 20" x 24").  But I also made some small PCBs back then too.

Also, most of my planned PCBs are "size sensitive".  Which means I need to keep them as small as possible (especially the larger ones).  Hence the even more urgent need for 0201s on large PCBs.
« Last Edit: May 10, 2016, 09:04:53 am by bootstrap »
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Offline vonnieda

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Re: New Pick and Place design ideas
« Reply #41 on: May 09, 2016, 03:13:49 pm »
Hi folks,

I'm the author of OpenPnP and I feel like I need to clear up a couple misconceptions about my software.

1. OpenPnP is not magic software. It's current vision algorithms are pretty basic and bottom vision is brand new. It's working well so far but I've only tested it with a few dozen different components.

2. I do not know of anyone using OpenPnP to place 0201s and < 0.5mm pitch components. Maybe someone is, but I haven't heard of it. That is not my target market. I'm primarily interested in 0603s and 0.5mm+ pitch components. The software is geared towards hobbyists, prototyping and small businesses. That isn't to say it can't do it, but for components that small it's more a matter of how precise your machine is versus how fancy the software is.

3. OpenPnP does not "require" steppers. As noted, the hardware interface is abstract. All OpenPnP cares about is whether your machine can move, pick, and place. It doesn't really care about how it goes about any of those steps and people have used it with machines that range from sticks, bubble gum, and hope to dual head 14 nozzle 2.5m/s linear servo monsters.

Hope this helps. If you have questions about OpenPnP or need anything clarified, we're a friendly bunch. Join the mailing list and introduce yourself: http://groups.google.com/group/openpnp

Thanks,
Jason
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Re: New Pick and Place design ideas
« Reply #42 on: May 09, 2016, 05:58:27 pm »
While not claiming to have the ability to jump ship and become a pick and place manufacturer - I do enjoy considering the issues. One of the biggest things to consider for anyone wanting to design and build one is to have some experience with the practical issues. I had designed and build a manual machine (very basic) and considered making a machine on a similar level to Lite Placer to help with my high density prototypes and short runs.

One day, I stumbled across my opportunity to buy and refurb a Quad machine. I threw myself into the pick-n-place fire instantly and had to deal with a mountain of issues from motion control to feeders and everything in-between. After getting the machine running in tip top shape, I was faced with the challenge of managing the process as a whole. This very steep learning curve totally changed what I would consider for building my own machine. Like @bootstrap said, I don't want to build the same old machine - I would only be motivated if I could see a path to delivering an innovation of some sort. Something that is uniquely helpful.

From a business perspective - I have never gone down the path of designing products to be a cheap as possible. I tend to go after the 'cost-effective' business solutions that are not the lowest cost, but have an excellent return. With PnP machines, a LOT of value is correlated with reliability AND speed. That is where the MyData class machines fit. They are reliable and extremely fast at the same time. Of course this also means that the entry level MyData machine is very expensive and only targets full time production. Sacrificing speed does indeed save a lot of money and I have always wondered what is the market size of a $20k PnP solution. At $10k, I think there are too many sacrifices to yield a machine suitable for a business. At $20k, I believe there is enough to work with to make a machine that has the right ingredients for small business in-house production work with modest volumes. That means the (in rough terms) the BOM plus labor would need to max out at under $10k if sales are direct and any profit is expected. The volume of sales has a lot to do with how that ratio is derived, but it is at least a rough starting point.

I would focus on a low cost feeder design. The machines core motion is relatively easy. A feeder scheme that can handle a very wide variety of parts with high-reliability and still be low cost will be key. I do, have a number of practical ideas (based on real concepts that I have already designed and built for other projects) to build a machine with very high feeder count, accuracy, and low cost to deal with low volume / high mix / fine pitch / low-modest speed. I have read a lot of 'overthinking' in this thread so far, the only way to get a low cost machine is by examining the real everyday issues and creating the simplest solutions possible to solve them in order of importance. Every nut, bolt, camera, connector, servo, etc adds to the challenge. Part presentation from the feeders is super important since the feeders are duplicated so many times on any given setup.

My current line of business is totally unrelated and it would require a career change to do anything with that. I have done a LOT of contract work in the past where my employers pay me by the hour to give up all of my concepts and ideas and they have literally made many 10's of $millions. That is my motivation to design my own products and get the upside benefit. My contract employers from the past essentially had the development capital and sales chain to take advantage of my ideas/designs/engineering/and implementations. These were great learning opportunities and I am grateful to have been able to see how a product goes from zero to hero. I am now saving all of my IP until a I can engage in a business opportunity that has an upside benefit. My eyes are always open to a new opportunity, but it has to be significantly better than the path I am currently on.

With that said - I am scared of going down the path of building machines with huge BOM counts and complex supply chains. Right now, I see more success in simpler projects (for me personally).
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Offline Spikee

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Re: New Pick and Place design ideas
« Reply #43 on: May 09, 2016, 10:57:11 pm »
I think that this design would be a good place to start from:

https://hackaday.io/project/9319-diy-pick-and-place

Belt driven (5mm  width or so), hiwin 2 contact 12mm wide rails, alu profiles.

This is what I would make of it:


For the Y axis 15mm hiwin 4 contact (HGR) bearing. Why? because it is pretty cheap, 4 contact and would allow the option to convert to small router or something like that.

For the X axis 35mm hiwin 4 contact (HGR) bearing. Why 35 mm? because the price difference is so low ... why not.  20-25mm would probably also be fine.
Instead of a small width belt the top design has and also my litplacer I would just put a oversized HTD 8M 30mm belt on it since it is not that much more expensive and will help to minimize backslash significantly.

For motors a 4 axis set of leadshine closed loop steppers. I have these on my cnc and they are great. I bought mine from ebay and they were not that much more expensive than a non closed loop stepper and leadshine driver. The encoder could be upgraded to 12 bit (is 10 bit std. , software supports 12bit).

Two motors on each of the y axis. Because 1. why not , 2. would allow possible cnc /... conversion.
 
For the head I would use (2 or 4 heads):
http://www.robotdigg.com/product/674/PNP+Machine+Nema11+Headset
with the samsung cp45 nozzle / holder instead of the Juki one's. As these are better nozzles in my opinion and allow auto change without buying any special adapters / actuators. Just pull the nozzle off with z-movement.

The x-axis profile is 80x60 x 660mm 8E LP , y-axis profile 80x160 8E SP 500mm (can be sized-up if needed).
The 30mm HTD belt would be enclosed in the 80x60 / 80x160 tube. Chain-guides to handle all the wires/pneumatics going to the head.

Design a enclosure around the frame to block outside light as this greatly influences the vision performance.
Have diffused white leds in the c-profile's , bottom of x-axis portal and even on the enclosure to ensure a "even" lighting condition at the base.

One could even use a t-slot plate in the middle of the base to allow easy mounting of pcb fixtures and the likes
I would use off the self (whatever works / is affordable / easy to use) feeders for this system. Using something like the openfeeder or whatever greatly increases time and manufacturing cost.

Design a machine like that would cost the following:
2x 500 mm hiwin HG15R rail =  80 euro
2x HGW15CC blocks = 68 euro
1x 660mm hiwin HG35R rail = 85 euro
1x HGW35CC block = 73 euro
HTD 8M 30mm belt is 20 euro per meter (4kN max allowed force)
Using a t-slot base would probably cost around 100-200 euro when using ISEL brand.
4x closed stoop stepper + driver is probably around 400 euro
Stepper shaft couplers = 100 euro
Then you need various pulleys, screws, washers ... = 100 euro
led stips probably another 100 euro
laser cut pvc/lexan/ .. enclosure probably 100-200 euro
Tiny G or whatever driver board 100 euro
various alu / plastic milled adapter plates 200 euro (when doing a group buy / china)
Since there is good even light a reasonable up/down cam is good enough = 100-150 euro
China inductive endstops = 50 euro
----
so for about 2000 euro ex tax via (all genuine parts) local  webshop (relatively expensive)
A really reasonable base can be constructed. With some shopping around / leaving t-slot out / downsizing 35mm rail one could even subtract around 300-500 euro from this.

I do not think that adding (cheap) ball-screws would add much speed/accuracy to this system.
The closed loop stepper driver can go up to 65535 micro-stepping.
On my machine it is at the default value of 1024 or so and I get 0.1mm repeat-ability with ease on a much heavier machine. Without doing any tuning.

This machine would be higher spec than quite a lot of hobby cnc routers I have seen. Thus it could also be used for various other configurations.

A machine like this should be able to place 0402 / 0201 mechanically without much problems. Doing visual calibration once in a while should make 0201 imperial placement have a low error rate of <1%.

If one want more feeders the width of the machine can be increased or the 'C' profiles can be changed to something else and allow feeders to come from all four sides.

Software would be openpnp or the likes with possible modifications.

« Last Edit: May 09, 2016, 11:06:00 pm by Spikee »
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Re: New Pick and Place design ideas
« Reply #44 on: May 09, 2016, 11:51:46 pm »
X/Y positioning is simple relative to the details of feeders, vision, nozzle changers, part release, pickup fault detection, fast part change over, tall parts, tube parts, etc are where things get challenging. All of those challenges start getting in the way of other things and the machine gets crowded and complicated very quickly. It seems that most discussions focus on the placement of the parts, where I would focus on how to deal with delivery and pickup of parts which where the real challenges are.

The PCB has fiducials and sits perfectly still the whole time. In a practical sense, there is no concern for vision focus, flex, or temperature on the placement end of the process. The feeders, on the other hand, have a much more challenging task of moving the tapes to the exact position and picking up the parts without them flipping on end or diagonally. The pickup part of the effort is where I have all of my problems - not putting the parts down. Most (if not all) high-end machines put an enormous effort into the feeders to reduce the mis-picks to a very low number. This effort makes the feeders very expensive and sophisticated. In my case (and many other businesses like mine) we need a lot of feeders on the machine so saving money here is a way to drastically reduce the overall solution cost.

Also, feeder banks would be on my ideal machine so that I can be loading a job of 40 feeders while the machine is using 40 different feeders. When it is time to switch - 2 banks of 20 feeders are swapped and ready in a minute, instead of loading each feeder one by one. Each feeder should have a QR code or bar coded that allows the machine to identify it and associate the part that was loaded. The QR code should be visible to the placement vision camera so it adds next to no cost at all. The software (including offline software for setup) is where the codes get matched with the parts.

The placement speed is generally not a limitation in a small entry level environment - it is machine setup and parts management. If I could have 40-60 parts in the machine on banks and swap out the banks in a minute or two to run a totally different job - the machine would be gold. The feeders would have to be very clever to achieve the precision and the low-cost which would allow a working set and a standby set of feeders to swap super fast.

I have made arc-second accurate positioners and very repeatable mounting fixtures for imaging (optical) - This is where I would put most of my efforts. After a feeder/pickup scheme is developed - I would then move on to the XY gantry and other systems.
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Re: New Pick and Place design ideas
« Reply #45 on: May 10, 2016, 12:03:46 am »
Quote from: bootstrap on May 09, 2016, 12:47:25 pm
I've never seen vias covered by soldermask.  My PCBs aren't that way.  Take a look at the images of two of my PCBs several messages back for examples (near bottom of page 1).

Every board I make has, by design, all of the vias covered with mask.  If you look at many professional boards they have them covered as well.  There are many good reasons to cover the vias, and few reasons not to.

However, if you know your placement machine relies on the vias then you can choose that at manufacturing time for the boards.

I also don't see why you can't/shouldn't use the footprint that you're placing the component on in your vision system.  Even with paste on it it should provide enough contrast that you should be able to place using the pad.

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Re: New Pick and Place design ideas
« Reply #46 on: May 10, 2016, 12:31:59 am »
Using pads with paste is an unnecessary risk. Vias are not all that great either since they are crowded by solder mask and are mostly small. Traditional fiducial marks are super reliable and provide more than enough information for nearly all placements. In very critical areas, you can always put a pair of local fiducials to better ensure success.

They are so easy to put in the PCB design and so easy for the machine to see - why would you avoid them? I have used vias and other holes as fiducials on PCB's I did with only hand assembly in mind, but it was more accurate and reliable when I add fids.
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Offline alexanderbrevig

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Re: New Pick and Place design ideas
« Reply #47 on: May 10, 2016, 03:46:12 am »
This discussion (of using vision for accurate mapping to a surface) reminds me of this https://glowforge.com/
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Re: New Pick and Place design ideas
« Reply #48 on: May 10, 2016, 04:03:25 am »
PCB's are a 2D world (right now anyway)

The requirements for vision are very straightforward in the big scheme of things. My smartphone has more than enough power to run an entire PnP machine.

As for that glowforge product, it looks like an expensive toy without much value.
 
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Re: New Pick and Place design ideas
« Reply #49 on: May 10, 2016, 04:39:12 am »
Quote from: rx8pilot on May 10, 2016, 04:03:25 am
PCB's are a 2D world (right now anyway)

Are you placing mass-less components? ;)

I guess the glowforge has value to those who find it valuable. Much like hobbyist PnP machines :)
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Re: New Pick and Place design ideas
« Reply #50 on: May 10, 2016, 04:51:18 am »
Quote from: rx8pilot on May 10, 2016, 12:31:59 am
Using pads with paste is an unnecessary risk. Vias are not all that great either since they are crowded by solder mask and are mostly small. Traditional fiducial marks are super reliable and provide more than enough information for nearly all placements. In very critical areas, you can always put a pair of local fiducials to better ensure success.

They are so easy to put in the PCB design and so easy for the machine to see - why would you avoid them? I have used vias and other holes as fiducials on PCB's I did with only hand assembly in mind, but it was more accurate and reliable when I add fids.

When designing boards, I always include fiducials...  sized appropriately for the machine.    The machine I have will place fine pitch components just fine... for chips it's down to 0201's.  (I use 0402's on my boards with no problems other than an occasional feeder alignment issue after swapping a reel).   But, this is also a commercial-grade machine which I paid large for.  I can also place fiducials around critical components but so far it hasn't been necessary. 

The suggestion I was making was basically that if your intent is to use imaging to help with position accuracy, and fiducials weren't good enough for whatever reason, imaging a pasted board is not out of the question.  I agree it's higher risk than fiducials, but if the goal is to build a very low cost machine which may have questionable mechanical positioning accuracy to be corrected with vision, then this might be a reasonable solution.  Of course the devil is in the details, and I'd have to see it work before I was 100% convinced.  But if the choice is between imaging potentially covered vias on a board vs a pasted pad, I think I'd bet on imaging the pasted pad.   
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Re: New Pick and Place design ideas
« Reply #51 on: May 10, 2016, 04:58:42 am »
I can get that concept, but after spending some time ( 10 years) designing and manufacturing precision motion mechanics - it's just not all that hard or expensive to make a suitably precise motion platform for even the tiniest of parts. That, in general, should eliminate the need for any fancy footwork in the vision system.

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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #52 on: May 10, 2016, 07:59:30 am »
Quote from: forrestc on May 10, 2016, 12:03:46 am
Quote from: bootstrap on May 09, 2016, 12:47:25 pm
I've never seen vias covered by soldermask.  My PCBs aren't that way.  Take a look at the images of two of my PCBs several messages back for examples (near bottom of page 1).

Every board I make has, by design, all of the vias covered with mask.  If you look at many professional boards they have them covered as well.  There are many good reasons to cover the vias, and few reasons not to.

However, if you know your placement machine relies on the vias then you can choose that at manufacturing time for the boards.

I also don't see why you can't/shouldn't use the footprint that you're placing the component on in your vision system.  Even with paste on it, it should provide enough contrast that you should be able to place using the pad.

I understand that a pick-and-place machine that requires exposed vias (or extra fiducials) may be considered less desirable by some (especially if they already have boatloads of bare PCBs in the back room they want to assemble).  That is a "negative" I am willing to accept if necessary.  Why?  Because the "target market" that I care about (and also think is an effective target market for a commercial venture) is real and wannabe electronics engineers who want to [design and] assemble non-trivial PCBs with the latest tiny and fine pitch components but can't afford $40K for a pick-and-place machine (complete with adequate number of feeders).

Note that I do not claim other target "markets" are not justified, but they don't interest me (unless they overlap the one I defined).  I am definitely not interested in competing with mydata or ddmnovastar or any of those existing medium-high end manufacturers (especially on the basis of speed, though we'll make ours as fast as possible while staying within our niche).

I don't think the advantages of covering vias is significant.  To everyone:  If I am wrong about that, please explain!

I very seriously doubt close and uncovered vias become shorted by solder more than once in a blue moon.  There shouldn't be solderpaste on the via.  When a via is super close to a component pad that does need soldermask, that could be an opportunity for smeared solderpaste and a short, but I believe the chances of that actually happening is extremely low.  So... I just don't see a significant advantage in covering vias, and not covering the vias has never caused me any problems or failures.

I do agree with your observation.  After I scanned PCB images on the internet, I did find that many PCBs have covered vias (probably half or so).  Nonetheless, if we need [some of] those vias exposed to make our machine more precise, cheaper or a better value, I'm willing to require this.

Note the following consideration too.  Engineers can trivially create two resist gerber files for one or both sides of the PCB (based upon whether components are placed on both sides or one).  So they can leave the vias uncovered on small runs of PCBs they intend to assemble themselves with our target machine, but switch to the other gerber file if and when they have assembly done elsewhere for high volume production.

The only negative I can identify so far is... if someone has a boatload of empty PCBs in the back room they want to assemble, and they already have the vias covered.  In those cases, if they can perform quality application of solder-paste, our software should be able to determine exact component position from the component pads themselves (which are definitely visible, since the component hasn't been placed yet).  In fact, I'm willing to be our software NEVER needs to look at via pads except for developers who have poor solder paste application equipment, or who make the openings in their stencils larger than necessary, or otherwise don't create properly prepared PCBs for assembly.

Note that all our software needs to find is 1~2 pad edges on each axis (x,y) that are not obscured by solder paste in order to precisely determine where the down-looking "nozzle camera" is located.  The chances we can't find that on components with many contacts is extremely low.  On components with only 2 or 3 contacts and poor solder paste application... that could happen, hence the desire to also have access to nearby vias (within the 50mm~100mm square centered on the component center).

Though it is tiny bit of extra work, engineers who hate uncovered vias can leave them all covered except 2~3 within the [50mm or] 100mm square around each component.  That's a pretty damn large area to only have 2~3 visible vias, so I can't imagine very many engineers will decide to spend $30K more just to avoid that requirement!  And if they apply solder paste properly, they won't need to leave any vias exposed at all.

BTW, the problem isn't contrast, the problem is confusing the software that determines position based upon the component pads.  To give an extreme example to make the point, imagine a component in which the solder paste extends beyond all 4 edges of every component pad.  Now the software cannot precisely determine the position of any one of those pads.  Who knows where the pads actually are?  The sloppy application of solder paste might be offset or rotated in any direction by any amount (up to some maximum)... no way to know.

The main problem here is software complexity.  If the software is made smart enough, it can look all over the place in that 100mm square centered on the component center, and try to find pads on other components to precisely determine position.  But if those components are already placed... no workie.  One could make the software even more complex and have the software scan the entire PCB to find components with problematic solder paste application (or any other reason that component cannot be precisely positioned).  It could then look around for other component pads in the 100m square field, and if it found them, delay the placement of those components until after the problematic component is placed.  But certain cases can turn into a multiple loop or non-resolvable dependency, which makes the software even more complex to recognize (and fail or seek alternatives).

BTW, if the component in question doesn't have fine pitch, it can be placed anyway, because lower precision will be possible by other means (either the mechanics themselves, or various alternatives I prefer not to waste your time on here and now).

Make sense?

PS:  If someone simply abhors covering vias, they are more than welcome to add a few more tiny "local" fiducials to their PCBs.  Just enough to assure 2+ are in each 100mm square portion of the PCB.  That's actually the best generic approach.  The only need for the via pad technique we're talking about now is to provide an easy, painless, automatic way to avoid the need for a few tiny fiducials on each PCB that are not required by more expensive pick-and-place machines.  On any PCB that has at least a few regions of the PCB that are not massively crowded with components, traces and vias, the extra tiny fiducials are trivial, and I'd say a "no brainer".  In fact, I'd call them "best practices" too.

Note that several of the neoden4 messages talk about errors that seem to increase in certain directions across the PCB surface (not necessarily x or y).  Can't be sure without knowing why this problem arises, but this problem might be solved for neoden4 too by adding a few more tiny fiducials on the PCB.  And I read (at least 2 or 3 times in the past 3~4 years) pick-and-place manufacturers encourage PCB designers to put more fiducials on the PCB if it is easy and convenient.  So... sounds like a good practice in any case.
« Last Edit: May 10, 2016, 08:09:31 am by bootstrap »
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Offline glenenglish

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Re: New Pick and Place design ideas
« Reply #53 on: May 10, 2016, 08:21:09 am »
Bootstrap says
"I've never seen vias covered by soldermask. "  :-DD
well i dunno where you have been....

The NORM is to tent your vias. Sometimes, selectively some vias are not tented for test points.


Yes NEVER NEVER except with NO OTHER option use via holes as fiducials.
They are drilled only well enough not to cause a plane short and nothing more....

The PCB fab people also will go to extra trouble also to ensure the fiducials are faithfully etched and not over/under etched.

g


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Offline alexanderbrevig

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Re: New Pick and Place design ideas
« Reply #54 on: May 10, 2016, 08:44:09 am »
Maybe we should start a new thread on tenting vias? Just to add, when using vias under ICs for thermal relief you actually want some solder to flow down (and your apertures adjusted for extra paste). Using tented vias under ICs I'm told is considered bad practice. The only other time I do not tent my vias is if I want them to serve as a test point (as already pointed out by glenenglish).
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #55 on: May 10, 2016, 09:02:42 am »
Quote from: vonnieda on May 09, 2016, 03:13:49 pm
Hi folks,

I'm the author of OpenPnP and I feel like I need to clear up a couple misconceptions about my software.

1. OpenPnP is not magic software. It's current vision algorithms are pretty basic and bottom vision is brand new. It's working well so far but I've only tested it with a few dozen different components.

2. I do not know of anyone using OpenPnP to place 0201s and < 0.5mm pitch components. Maybe someone is, but I haven't heard of it. That is not my target market. I'm primarily interested in 0603s and 0.5mm+ pitch components. The software is geared towards hobbyists, prototyping and small businesses. That isn't to say it can't do it, but for components that small it's more a matter of how precise your machine is versus how fancy the software is.

3. OpenPnP does not "require" steppers. As noted, the hardware interface is abstract. All OpenPnP cares about is whether your machine can move, pick, and place. It doesn't really care about how it goes about any of those steps and people have used it with machines that range from sticks, bubble gum, and hope to dual head 14 nozzle 2.5m/s linear servo monsters.

Hope this helps. If you have questions about OpenPnP or need anything clarified, we're a friendly bunch. Join the mailing list and introduce yourself: http://groups.google.com/group/openpnp

Thanks,
Jason

Jason, thank you VERY MUCH for posting your message.  To make wise decisions we need facts, not rumors... especially me!  I have a few questions for you.

If some of us collaborate to create a new pick-and-place machine, I assume we'll save a LOT of time if we can adopt OpenPnP.  Do you agree, or do you think we will actually waste time by adopting OpenPnP because we intend to do more by vision than you probably ever intended to do?  If you need to have a basic idea of the series of steps this configuration we're considering requires, search through my previous posts in this topic to find the one that lists all those steps (in terms of processes A, B, C, D, E, F...).

-----

After reading your description of your "target market", I'm not entirely certain whether ours is very similar, or outside (speaking of "in your opinion" here).  Let me say a few things that make me think our target is compatible with yours.

Note that the below is mostly my opinion, but slightly blended with comments from others in this forum who seem serious about being part of this project if we converge on a very worthwhile configuration.

#0:  So far we describe our "target market" something like this:  For independent engineers and wannabe engineers (hobbyists) who want to reliably place tiny (<= 0201) and fine-pitch (<= 0.50mm) components but cannot afford the cheapest commercial machines with these capabilities ($40K up) and are willing to happily accept up to a 2x to 5x slower placement rate than the cheapest commercial machines, and possibly other [optional] "minor inconveniences" (perhaps regarding feeders).

#1:  We learn towards making the machine "open hardware design" at the same time as possibly offering finished units (or maybe even kits, though I personally dislike that option).

#2:  Any added capabilities or features we add to OpenPnP would become part of the OpenPnP project (unless you object).  The nominal plan would be to NOT change how OpenPnP does anything, but to add additional options or paths to what you have setting a few variables (or equivalent) in OpenPnP makes it run the code paths compatible with our approach.  Others could subsequently design pick-and-place machines that adopt some or all of our approaches and set their variables accordingly.

#3:  Our "target market" is "cheap but not too cheap to achieve our goals".  I think somewhere between $10K and $20K is likely as a purchase price for a new unit.

#4:  Our primary goals are: "be able to precisely and reliably place 0201 or smaller discrete components" and "be able to precisely and reliably place fine pitch components with hopefully 0.30mm+ pitch but at worst 0.50mm pitch" and "cost much less than commercial machines" and "accept 2x to 5x slower performance than commercial machines that can place similar components".

Therefore, as far as I can tell, we are consistent with your target market in terms of price.  As long as you don't object to the ability to place smaller components than your hardware implementations currently support, then I see our "target markets" as mostly or entirely overlapping.  But what matters is what you think.

#5:  I believe we would strongly resist creating a "new branch" of OpenPnP to add support for the elements of our approach.  Why?  Because we'd want all future capabilities and enhancement that you and your collaborators make to become available to our machines too.  If we "branch off", updating our software from time to time would require much more work, and there is always a chance you would do something in the code or architecture that prevented such upgrades (or made them messy or extremely difficult).

#6:  We would probably adopt OpenCV whether we adopt OpenCV.  I assume you adopted OpenCV for OpenPnP.  Is that correct?  If not, what?

#7:  At least some of our cameras will have resolutions of at least 4K x 4K (though further brainstorming could reduce that to 2K x 2K).  I assume OpenPnP can work with high resolution cameras.  If that is a false assumption, please explain.

#8:  We plan to implement a couple unconventional approaches with vision in our approach as a way to enable extreme precision (to support 0201 and 0.50mm and smaller) with "crappy mechanics".  Maybe we should say "modest mechanics", but probably the more accurate term would be "variable quality mechanics".

-----

If you have lots of time, you can get an even more detailed impression of our goals by reading this whole topic (or at least messages I wrote, which include and reply to most other important messages).  But the above works as a general guideline if you want to save the time and misery of reading all those messages.

BTW, if you're willing to give us an rough estimate of how much time would be required to re-create what you've done so far, please do!  I hope we don't need to do that, but... who knows at this point?  Certainly not me.

Again, thanks very much for responding to this topic!
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #56 on: May 10, 2016, 09:16:39 am »

if(glenenglish == bootstrap)
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #57 on: May 10, 2016, 09:26:09 am »
I'd agree that using untented vias is a reasonable compromise to allow top-vision to improve accuracy, but you may still have issues with things like soldermask alignment affecting the accuracy.

If there was a way to accurately measure head position then that would potentially allow the use of cheap mechanics, but I don't think visioning a pasted board is it. Visioning vias might be, but I'm not convinced.

A reason to use tented vias is if there is any flowsoldering or wavesoldering of through-hole parts, so it tends to be the default.

However feeders are still the thing that really need solving for cheap pick/place, and as you get down to smaller parts, feeder performance gets increasingly critical
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #58 on: May 10, 2016, 09:33:46 am »
Quote from: rx8pilot on May 10, 2016, 12:31:59 am
Using pads with paste is an unnecessary risk.  Vias are not all that great either since they are crowded by solder mask and are mostly small.  Traditional fiducial marks are super reliable and provide more than enough information for nearly all placements.  In very critical areas, you can always put a pair of local fiducials to better ensure success.

They are so easy to put in the PCB design and so easy for the machine to see - why would you avoid them? I have used vias and other holes as fiducials on PCB's I did with only hand assembly in mind, but it was more accurate and reliable when I add fids.

You posted some great messages in this topic I still need to reply to tonight, but I'll start with this short and simpler message to get myself up to speed.

The key of the approach I described previously in this topic is to apply vision on the real world (components, PCB pads, possibly the x,y rails, and so forth) more than conventional pick-and-place machines do... in order to make reliable and precise placement of very tiny and fine pitch components without massive, precise, expensive mechanics.

If we end up with a design that doesn't go that way, then much of what I say here and elsewhere may fly right out the window and become irrelevant.  However, assuming for now the previous paragraph applies, I'll reply to your message.

#1:  I suspect any good computer vision package can precisely determine position of small via pads (to roughly the same accuracy as standard fiducials).

#2:  I agree that explicit placement of a few additional fiducials when necessary is the preferred approach and practice, and we should encourage all PCB designers who intend to adopt our machine to place one or more [tiny] "local fiducials" AKA "secondary fiducials" on their PCBs.  If they do this, we can tell the software to completely ignore via pads and component pads.  Only when PCB designers are too stubborn to add "local fiducials" would the machine [optionally] fall back on code to attempt the equivalent with via pads and/or component pads.

#3:  I suspect components pads will usually be sufficient even without vias, but on PCBs where solder paste is badly applied and smeared in irregular fashion beyond the edges of most component pads, inferring the component pad positions will be problematic and unreliable (to varying degrees depending on each case), in which case uncovered via pads become our last fallback (other than refuse to continue or risk unreliable placement).

#4:  We are nominally assuming the camera has a 4K x 4K pixel field that images a 4" x 4" (or perhaps 100mm x 100mm) square on the PCB, making each pixel correspond to 0.001" == 0.025mm == 25 microns on the PCB.

#5:  Fairly straightforward image processing techniques should let us infer positions to about half of that (0.0005" == 0.012mm == 12 microns).  This should be sufficient for placement of 0201 and smaller, and 0.30mm pitch and maybe a slightly smaller given our approach.

#6:  I am very much in favor of "local fiducials" as primary method, with component pads being a secondary method (only when "local fiducials" cannot be found in the image), with via pads being the last fallback.

#7:  I am also willing to say to potential adopters and buyers, "don't be jerks, make sure the 100mm square centered on every tiny (<= 0402) or fine-pitch (<= 0.80mm) component contains at least 2 "local fiducials".  The whole "via pad issue" doesn't even arise when our adopters "do the right thing" and comply.  I don't think we're asking very much to save them tens of thousands of dollars on a pick-and-place machine!  I'm willing to be overruled on this one if others involved in the project want to require adopters/buyers include those "local fiducials".
« Last Edit: May 10, 2016, 11:15:07 am by bootstrap »
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #59 on: May 10, 2016, 09:54:29 am »
Quote
#1:  I suspect any good computer vision package can precisely determine position of small via pads (to roughly the same accuracy as standard fiducially).

OpenCV will do a very good job now.  The challenges are having good enough cameras and how long you are prepared to wait to process it. ( and/or how much processing power you want to apply to the problem ).  Theres quite a few algorithms you could use.   

Quote
#2:  I agree that explicit placement of a few additional fiducials when necessary is the preferred approach and practice, and we should encourage all PCB designers who intend to adopt our machine to place one or more [tiny] "local fiducials" AKA "secondary fiducials" on their PCBs.  If they do this, we can tell the software to completely ignore via pads and component pads.  Only when PCB designers are too stubborn to add "local fiducials" would be [optionally] fall back on code to attempt the equivalent with via pads and/or component pads.

Just point them to the relvenent part of the IPC standards ( http://www.ipc.org ).. SMEMA 3.1.   No need to reinvent a standard thats been well thrashed out already.

Quote
#3:  I suspect components pads will usually be sufficient even without vias, but on PCBs where solder paste is badly applied and smeared in irregular fashion beyond the edges of most component pads, inferring the component pad positions will be problematic and unreliable (to varying degrees depending on each case), in which case uncovered via pads become our last fallback (other than refuse to continue or risk unreliable placement).

DFM is such an important part of designing a pcb, that you don't need to worry about this.  If you have gone to the effort of designing a system like you are describing, why would you design a pub with such fundamentally important features missing?   This is not a consumer product, you don't have to design to the lowest common demoniator.

Quote
#6:  I am very much in favor of "local fiducials" as primary method, with component pads being a secondary method (only when "local fiducials" cannot be found in the image), with via pads being the last fallback.

Just refer to the above standards..

On feeders, spend $50 on some Yamaha CL Clone feeders for 8mm tape.. ( they work with 0201+ ) The are very reliable, very available and just work.     You can also achieve reliable pick up from cut tape in simply made holders..   They just take more time to set up, but are fine if you are only putting 10-20 parts down.. 
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #60 on: May 10, 2016, 09:54:45 am »
Quote from: rx8pilot on May 10, 2016, 04:58:42 am
I can get that concept, but after spending some time ( 10 years) designing and manufacturing precision motion mechanics - it's just not all that hard or expensive to make a suitably precise motion platform for even the tiniest of parts.  That, in general, should eliminate the need for any fancy footwork in the vision system.

I think you and I have a similar "psychological" challenge on this project (a challenge that I may be finding a bit easier so far).  What I mean is, apparently both of us have made very... even extremely... precise mechancial systems in the past.  So we both know "how to design and fabricate that way", and we are aware of various tricks and methods that make this easier or more practical.

BUT... in this project we're trying to adopt an approach that can make inexpensive and simple-as-possible mechanical systems reliably and precisely place extremely tiny and fine-pitch components that many professional machines cannot do or have reliability problems with.

To be realistic, I think we need to [somewhat] disregard our expertise in precision mechanical systems.  Otherwise we risk finding out inexpensive simple mechanics just isn't up to the job.

What "target markets" we decide to support is relevant too.  If we want to put an "open-hardware design" out there based on our project, we have no control over how precise are the mechanics others build.  Obviously we do have such control over machines we build and sell, so we need to identify what range of "target markets" we intend to support before we know how to optimize the design approach.

I agree that a machine that can "do the job" of reliably and precisely placing tiny and fine-pitch components can either be based upon "machine design and machine precision" or "vision feedback and application of vision techniques to more of the pick-and-place processes".  I've been leaning towards the later because dozens of pick-and-place companies charge huge bucks for their [mostly] precision-mechanics based machines... and many of them still don't support 0201 and 0.50mm at all, or don't support 0201 and 0.50mm pitch reliably, or don't support 0201 and 0.50mm pitch reliably for all their customers.

I am probably just as confident as you in my ability to design and fabricate super-precise mechanics.  Maybe you know how to do so at somewhat lower cost than I do (based on your messages).  But I am still skeptical that leaning on mechanics is the wise and cheap path to such reliable and precise placement of tiny and fine pitch components.

We'll just need to brainstorm this and the other issues out more in subsequent conversations (which maybe should include one or more long brainstorming sessions by text+voice skype or telephone).
« Last Edit: May 10, 2016, 11:20:17 am by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #61 on: May 10, 2016, 10:43:53 am »
Quote from: mrpackethead on May 10, 2016, 09:54:29 am
Quote
#1:  I suspect any good computer vision package can precisely determine position of small via pads (to roughly the same accuracy as standard fiducial).

OpenCV will do a very good job now.  The challenges are having good enough cameras and how long you are prepared to wait to process it. ( and/or how much processing power you want to apply to the problem ).  There's quite a few algorithms you could use.   

Quote
#2:  I agree that explicit placement of a few additional fiducials when necessary is the preferred approach and practice, and we should encourage all PCB designers who intend to adopt our machine to place one or more [tiny] "local fiducials" AKA "secondary fiducials" on their PCBs.  If they do this, we can tell the software to completely ignore via pads and component pads.  Only when PCB designers are too stubborn to add "local fiducials" would be [optionally] fall back on code to attempt the equivalent with via pads and/or component pads.

Just point them to the relevant part of the IPC standards ( http://www.ipc.org ).. SMEMA 3.1.   No need to reinvent a standard that's been well thrashed out already.

Quote
#3:  I suspect components pads will usually be sufficient even without vias, but on PCBs where solder paste is badly applied and smeared in irregular fashion beyond the edges of most component pads, inferring the component pad positions will be problematic and unreliable (to varying degrees depending on each case), in which case uncovered via pads become our last fallback (other than refuse to continue or risk unreliable placement).

DFM is such an important part of designing a pcb, that you don't need to worry about this.  If you have gone to the effort of designing a system like you are describing, why would you design a pub with such fundamentally important features missing?   This is not a consumer product, you don't have to design to the lowest common denominator.

Quote
#6:  I am very much in favor of "local fiducials" as primary method, with component pads being a secondary method (only when "local fiducials" cannot be found in the image), with via pads being the last fallback.

Just refer to the above standards..

On feeders, spend $50 on some Yamaha CL Clone feeders for 8mm tape.. (they work with 0201+) The are very reliable, very available and just work.     You can also achieve reliable pick up from cut tape in simply made holders..   They just take more time to set up, but are fine if you are only putting 10-20 parts down..

###############################################

Quote
OpenCV will do a very good job now.  The challenges are having good enough cameras and how long you are prepared to wait to process it (and/or how much processing power you want to apply to the problem).  There's quite a few algorithms you could use.

Yes, yet another issue to consider carefully (like we don't already have enough).  How much processing to require from the hardware and microcontrollers in the machine (which we need to pay for and ship), and how much processing to require of the PC that the operator interacts with.

The more we require of the PC, the more complex the OpenPnP software (and/or the special-purpose OpenPnP "plug-in" for our machines) need to be.  But also, the less we require from our machine components, the less the machine will cost, which lowers selling price).  On the other hand, speed may be slower on slower PCs.

The more we require from the machine, the less complex the OpenPnP software (and/or the special-purpose OpenPnP "plug-in" for our machines) need to be.  But also, the more we require from our machine components, the more the machine will cost, which raises selling price).  On the other hand, speed should never suffer due to PC speed.

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Just point them to the relevant part of the IPC standards ( http://www.ipc.org ).. SMEMA 3.1.   No need to reinvent a standard that's been well thrashed out already.

I have no desire to re-invent wheels that don't gain us substantial benefits.

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DFM is such an important part of designing a pcb, that you don't need to worry about this.  If you have gone to the effort of designing a system like you are describing, why would you design a pub with such fundamentally important features missing?   This is not a consumer product, you don't have to design to the lowest common denominator.

Excuse me for sounding like a moron, but what do "DFM" and "pub" mean?

The target market for this machine is definitely not "lowest common denominator".  However, while we're not gonna end up anywhere near "the cheapest machine", one of the most important goals is to precisely and reliably place components too tiny or fine-pitch for existing "lowest common denominator" machines (and even some lowish-end commercial machines).

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On feeders, spend $50 on some Yamaha CL Clone feeders for 8mm tape ( they work with 0201+).  They are very reliable, very available and just work.  You can also achieve reliable pick up from cut tape in simply made holders.   They just take more time to set up, but are fine if you are only putting 10-20 parts down..

I personally don't have enough practical experience with pick-and-place machines to make decisions about feeders yet.  But feeders do seem to be one of the two biggest issues we must tackle to make this machine cost-effective and "fabulous".

I have no objections to adopting inexpensive but reliable and highly capable feeders that exist already... if that turns out to be the best approach.

While I tend to shy away from "lowest common denominator", I would like to at least consider ways to ALSO support extremely simple (even "feeder-free") alternatives for engineers who only make small boards with limited number of components, but do need to support tiny and fine-pitch components... an optional sub-target market (advanced hobbyists)?

Question:  Why do you say those feeders work down to 0201 rather than "8mm tape"?  Why would the feeders not work with smaller than 0201 components as long as the components are still on 8mm tape?[/font]
« Last Edit: May 10, 2016, 11:26:24 am by bootstrap »
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Offline Koen

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Re: New Pick and Place design ideas
« Reply #62 on: May 10, 2016, 10:50:36 am »
Spikee, open a new topic with your build if you wish. Some of your points will cause you more problems then they'll solve.
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #63 on: May 10, 2016, 10:51:33 am »
Quote from: bootstrap on May 10, 2016, 10:43:53 am
Question:  Why do you say those feeders work down to 0201 rather than "8mm tape"?  Why would the feeders not work with smaller than 0201 components as long as the components are still on 8mm tape?[/font]
Repeatability of pick position, and not bouncing parts out.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #64 on: May 10, 2016, 10:55:48 am »
Quote from: glenenglish on May 10, 2016, 08:21:09 am
Yes, NEVER, NEVER except with NO OTHER OPTION use via holes as fiducials.  They are drilled only well enough not to cause a plane short and nothing more....

The PCB fab people also will go to extra trouble also to ensure the fiducials are faithfully etched and not over/under etched.

I know it is too much to read every mention, so I'll just firmly agree with your claim that via holes are NOT positioned well enough for determining positions.

That is ABSOLUTELY CERTAIN.

But that is also why I always say "via pads", not "via holes" (or just "vias", unless I accidentally omit "pads").

The via pads are etched on the PCB along with all component pads and fiducial marks.  So they are all on the same "playing field" so to speak, and thus precisely enough positioned relative to each other to precisely determine position (with adequate image processing routines).
« Last Edit: May 10, 2016, 11:27:01 am by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #65 on: May 10, 2016, 11:02:35 am »
Quote from: mikeselectricstuff on May 10, 2016, 10:51:33 am
Quote from: bootstrap on May 10, 2016, 10:43:53 am
Question:  Why do you say those feeders work down to 0201 rather than "8mm tape"?  Why would the feeders not work with smaller than 0201 components as long as the components are still on 8mm tape?[/font]
Repeatability of pick position, and not bouncing parts out.

Yes, if the feeders bounce < 0201 components out, that definitely rules them out for < 0201 components!

However, if we adopt the technique I suggested, where the down-looking "nozzle camera" precisely locates where each tiny component is before it moves the nozzle into position and lowers it to the component, then how precise the feeder locates the component does not matter (unless it also wanders around).

Note that the above "extra" step will not be required on components above whatever size the machine and feeder mechanics handles reliably.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #66 on: May 10, 2016, 11:12:27 am »
Quote from: Koen on May 10, 2016, 10:50:36 am
Spikee, open a new topic with your build if you wish. Some of your points will cause you more problems then they'll solve.

Just to clarify...

You say this because you believe the precision he claims will not be reliable and repeatable on every instance of hardware... and thus not appropriate to base a new design on?

If so, that's my take too, though I am impressed he can get so much from such a cheap machine.
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #67 on: May 10, 2016, 11:25:01 am »


Quote
DFM is such an important part of designing a pcb, that you don't need to worry about this.  If you have gone to the effort of designing a system like you are describing, why would you design a pub with such fundamentally important features missing?   This is not a consumer product, you don't have to design to the lowest common denominator.

Excuse me for sounding like a moron, but what do "DFM" and "pub" mean?
[/quote]

DFM - Design for Manufacture.   The practice of considering how you will make something, as well as what you are making.     For example i can "design" a 60,000km diameter sphere in 3D cad, with 1um surface flatness but in all likelihood i'd struggle to make one...  good DFM practice helps you avoid such issues.

Pub, sorry typo.  should have been PCB.

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Question:  Why do you say those feeders work down to 0201 rather than "8mm tape"?  Why would the feeders not work with smaller than 0201 components as long as the components are still on 8mm tape?[/font]

Because i'm talking from real experience and know they do..  i've not had reason to work with smaller ones, and not even gone looking...   
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Offline Koen

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Re: New Pick and Place design ideas
« Reply #68 on: May 10, 2016, 11:31:44 am »
No, I believe Spikee could make more efficient choices. We'll see if he opens a new topic.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #69 on: May 10, 2016, 11:36:31 am »
In a manner of speaking, the main point of this exercise is DFM (design for manufacture), albeit with a slightly difference focus than usual.  What I mean is, the main point is to "get precise and reliable" from "easily/cheaply/simply manufactured and assembled parts".

I have another principle of my own, which I suppose would be called DFF if it was a common term.  DFF would mean "design for future".  This can have more than one emphasis, but here the point is to design to support [as many as possible of] the most advanced components of today [and near future], so the machine is capable of most applications of today, and remains capable of most applications for years to come.  This can also imply "don't bother just copying existing designs and products".

What "fundamentally important features missing" from the PCB do you refer-to?
« Last Edit: May 10, 2016, 11:40:43 am by bootstrap »
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #70 on: May 10, 2016, 12:03:28 pm »
Quote from: mikeselectricstuff on May 10, 2016, 09:26:09 am
However feeders are still the thing that really need solving for cheap pick/place, and as you get down to smaller parts, feeder performance gets increasingly critical
I wonder if alternative designs where made for feeders.
It will take out of the box thinking.
Packaging such small components in paper tape with plastick strips is not a good design, probably cost efficient.
Are there machines out there that have a picking and sorting stage before the head picks it up and places the component?
How do these P&P shooters work with small components?
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #71 on: May 10, 2016, 12:40:22 pm »
Quote from: rx8pilot on May 09, 2016, 05:58:27 pm

While not claiming to have the ability to jump ship and become a pick and place manufacturer - I do enjoy considering the issues.  One of the biggest things to consider for anyone wanting to design and build one is to have some experience with the practical issues.  I had designed and build a manual machine (very basic) and considered making a machine on a similar level to Lite Placer to help with my high density prototypes and short runs.

One day, I stumbled across my opportunity to buy and refurbish a Quad machine. I threw myself into the pick-n-place fire instantly and had to deal with a mountain of issues from motion control to feeders and everything in-between. After getting the machine running in tip top shape, I was faced with the challenge of managing the process as a whole.  This very steep learning curve totally changed what I would consider for building my own machine.  Like @bootstrap said, I don't want to build the same old machine - I would only be motivated if I could see a path to delivering an innovation of some sort.  Something that is uniquely helpful.

Yes, and I'm keenly aware that I have almost no personal/practical experience with SMT assembly equipment (solder-paste stencils, pick-and-place machines, reflow-ovens, PCB cleaning systems for SMT).  While I've designed and assembled literally dozens of my own PCBs for my own projects over the years, they were primarily components with leads or pins that are inserted into "through-holes".  After doing mostly technology/architecture/system/software design for several years, I return to hardware (what I typically call "electronics") and find pretty much all components I need for my projects are SMT only (or the non-SMT are huge or somehow lame).

So my major hope for being here is to interact with people who have the SMT experiences I don't.  While I've been searching and reading about SMT on the internet for 4~5 years, I know how valuable practical experience can be.

I would definitely imagine you learned a lot from that Quad machine experience!

Any sane individual who knows how much time, effort and expense will be involved in a project like we're discussing here will be very hesitant to "dive in".  I can live and develop projects on my savings from previous projects, which it sounds like you can't do... or more precisely, which you're not insane enough to do unless you are seriously convinced to quit or pull back on paying contracts.  I totally understand and relate-to that.  I've been self-employed since before I finished school, and have never been an employee.  I've done contracts for the likes of AMD, NASA, AirForceResearchLabs and various observatories over the years, but they were all special-purpose contracts, not employment.

But since you are also a contractor, maybe you can reduce the time you spend on contracts while you collaborate on a project like this... ASSUMING YOU BECOME CONVINCED WE HAVE SOMETHING SO COOL YOU CANNOT RESIST.  That also tends to be my criteria for doing a project or not!

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From a business perspective - I have never gone down the path of designing products to be a cheap as possible.  I tend to go after the 'cost-effective' business solutions that are not the lowest cost, but have an excellent return.  With PnP machines, a LOT of value is correlated with reliability AND speed.  That is where the MyData class machines fit.  They are reliable and extremely fast at the same time.  Of course this also means that the entry level MyData machine is very expensive and only targets full time production.  Sacrificing speed does indeed save a lot of money and I have always wondered what is the market size of a $20k PnP solution.  At $10k, I think there are too many sacrifices to yield a machine suitable for a business.  At $20k, I believe there is enough to work with to make a machine that has the right ingredients for small business in-house production work with modest volumes.  That means the (in rough terms) the BOM plus labor would need to max out at under $10K if sales are direct and any profit is expected.  The volume of sales has a lot to do with how that ratio is derived, but it is at least a rough starting point.

I tend to prefer projects that are nearer the low-end than the high-end, but never too near the low-end.  I think this fairly well matches your position too.  My goal is for a $10K selling price that I don't want to allow to go above $20K during the development process.  It is my opinion that MAYBE the new forms of applying machine vision will make it possible to achieve the $10K goal, or at least substantially below the $20K price point (at the same kind of direct selling and markup you mention).  Since our target market will not be "rich corporations", you'll probably also agree that our support may be mostly on a forum, where adopters of our machine help each other, and we only need to spend time when we disagree with that help (or someone wants to pay us to get help).  I don't think we should charge for support that results from our machine suffering defects though.  You probably agree (more or less).  In other words, I envision NO showroom, NO salespeople, almost no marketing that costs us money, etc.

This is one reason to make a machine that satisfies a niche that NOBODY ELSE SATISFIES.  The fact is, most of my projects (that weren't on contract for existing corporations) were devices or technologies that DID NOT EXIST.  In other words, no competition!  If someone wants what we make, they have nowhere else to go.

We won't be in quite that situation, but we will be within the niche we define... if we meet our goals.  If we don't, we shouldn't even start making or selling anything.

I'll bet you agree with that much.

PS:  I am also a fanatic about simplicity and low part count (especially simplicity).  In some cases I've knocked that ball out of the park in into orbit in the past.  With this project, I don't yet see the opportunity to excel that far, but we should at least be able to KISS (keep it simple, stupid).

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I would focus on a low cost feeder design.  The machines core motion is relatively easy.  A feeder scheme that can handle a very wide variety of parts with high-reliability and still be low cost will be key.  I do have a number of practical ideas (based on real concepts that I have already designed and built for other projects) to build a machine with very high feeder count, accuracy, and low cost to deal with low volume / high mix / fine pitch / low-modest speed. I have read a lot of 'overthinking' in this thread so far, the only way to get a low cost machine is by examining the real everyday issues and creating the simplest solutions possible to solve them in order of importance.  Every nut, bolt, camera, connector, servo, etc adds to the challenge.  Part presentation from the feeders is super important since the feeders are duplicated so many times on any given setup.

Yes, from my reading, feeders are a crucial part of the project.  For example, they are a significant portion of the cost if I buy an LE40V from ddmnovastar.  And I've read lots of complaints about feeder costs and feeder reliability over the past couple years.

I am hoping our machine can ALSO (not the common case) support that portion of our "target market" who makes [usually] small PCBs with small to modest quantities of only a few components on each PCB... BUT... wants to start adopting the latest, greatest tiny and/or fine-pitch components.  I sorta see this as a sub-niche that might be called "super-hobbyist" or for some nano-company to make higher-end "super-hobbyist products" (better, more capable, more flexible, or more elaborate than sparkfun or pololu PCBs).

I agree about what you say regarding feeders.  Without making the lower-end of our "target market" burdened with anything huge or complex, I would never-the-less love to be able to support a large variety of feeders, and even for the operator to be setting up feeders for the next job while the current job runs.  Though, if we find a way to support an insane number of feeders, that becomes less important.  Only a total moron of an engineer would not adopt the same caps, resistors and common components for all his PCBs without a damn good reason, so I have to assume only 50% of feeders on the current job would typically need to be changed for the next job (plus or minus 25%).

I have a couple seriously unique ideas about feeders that will definitely need a mind with feeder experience to brainstorm with me.  One of them that has a LOT of benefits more-or-less assumes (to an extent, though not rigidly) that all of each component is placed before other components are placed.  Ask me further about that later, either in text here, or in a skype or phone conversation.

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My current line of business is totally unrelated and it would require a career change to do anything with that.  I have done a LOT of contract work in the past where my employers pay me by the hour to give up all of my concepts and ideas and they have literally made many 10's of $millions.  That is my motivation to design my own products and get the upside benefit.  My contract employers from the past essentially had the development capital and sales chain to take advantage of my ideas/designs/engineering/and implementations.  These were great learning opportunities and I am grateful to have been able to see how a product goes from zero to hero.  I am now saving all of my IP until a I can engage in a business opportunity that has an upside benefit.  My eyes are always open to a new opportunity, but it has to be significantly better than the path I am currently on.

I totally understand.  One instance of my IP could make me billions of dollars... easy and without question.  But I'd have to sell it to a government or military (or their contractor), and shortly thereafter (a few months or years) 99% of humans would be gone.  But the technology has an equally if not more awesome potential for advancement and benevolent application (which would also assure that disaster can never happen once someone else figures this technology out).  The fallout of that is that I haven't gotten investment, because those with a few million or more to spend always want control of the technology more than the benefits.  I went around in circles with Steve Jobs about this when he was still breathing.  Turns out, it might have saved his life.  I'm sure 99% of people with an opportunity to become a billionaire would jump at the chance no matter what the consequences.  I'm one of the few that riches alone will not sway, especially in the face of such extreme consequences.  But... now I've gotten way too far off topic.

What I wanted to ask is this.  Do you have to eject what you're doing totally out the airlock to work on a project like this... when you have one or two other collaborators with talents, abilities and expertise in the same ballpark as you?

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With that said - I am scared of going down the path of building machines with huge BOM counts and complex supply chains.  Right now, I see more success in simpler projects (for me personally).

Yes, in general I favor smaller projects too.  Unfortunately, my "ultimate project" (mentioned above) isn't tiny.  It does involve a few rather independent subsystems that can be products.  One of those may not be too huge or expensive, but requires javascript, a language that drives me nuts, and I am thus not efficient on.  So I'll probably subcontract that one out.  But the other subsystems are not quite in the category of "simple"... though most of them do tend to be simple to extremely simple mechanically.  One of these is an advanced "robotics vision system", which is mostly just a fancy term for a small, simple, compact, rugged camera that performs a small to modest amount of very specific and extremely crucial image processing (of sorts) in "hardware" (largely in the FPGA, actually) inside the camera... and sends super-crucial information about each image in the video stream to the PC (along with the uncompressed or lossless compressed image).[/font]
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #72 on: May 10, 2016, 12:53:40 pm »
Quote from: Kjelt on May 10, 2016, 12:03:28 pm
Quote from: mikeselectricstuff on May 10, 2016, 09:26:09 am
However feeders are still the thing that really need solving for cheap pick/place, and as you get down to smaller parts, feeder performance gets increasingly critical

I wonder if alternative designs where made for feeders.  It will take out of the box thinking.  Packaging such small components in paper tape with plastic strips is not a good design, probably cost efficient.  Are there machines out there that have a picking and sorting stage before the head picks it up and places the component?

How do these P&P shooters work with small components?

Well, since I (and others) consider myself a world class "outside the box thinker", the issue of feeders on this proposed machine is one way to test that claim!  Uh, oh.  Set myself up there!

Obviously we need to assume whatever "mechanics" component suppliers offer their components in, which seems to primarily be "tape", "trays" and "tubes".  Anything else?

Nonetheless, you are absolutely correct that IF we can get a huge benefit of some kind, the components can go through a pre-processing of some kind (remotely or on-machine) to put the components into a better form or state for the machine.  What to do, however, obviously isn't obvious yet.

I've seen one or two "shooter" videos on youtube, but the ones I saw picked up the components from what looked like conventional reels of 8mm tape.

PS:  Now that you mention it, I don't see why they didn't just stack up a whole bunch of those components right against each other in a tube with the same ID as the component rectangle (which would have to have a spring-loaded pusher at the opposite end from where the components exit the tube.  Except, of course, if any slack in the pusher ever developed, components in the tube would rotate, get flipped, get jammed or otherwise messed up.  So I guess I see why that didn't happen.  Sure would have been a lot more compact though!
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Offline Spikee

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Re: New Pick and Place design ideas
« Reply #73 on: May 10, 2016, 12:59:03 pm »
Regarding feeders. just put a camera above the pickup places (or a few) and just measure the rotation / location offsets while the head is moving.
Using this method something like the cheap neoden 4 feeders can be used. No need for (ultra) precise >150$ feeders.

Or the other method:
Expose more than one component at a time, take picture, calculate offsets for them all (lets say 5 components) -> save those values -> pick and place
When you know in software that 5 are placed you can just expose another 5 components and repeat the process. This would be a mix between a tape pulling feeder and sticking component strips to the table.
« Last Edit: May 10, 2016, 01:02:32 pm by Spikee »
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #74 on: May 10, 2016, 01:07:53 pm »
Quote from: bootstrap on May 10, 2016, 12:53:40 pm
Now that you mention it, I don't see why they didn't just stack up a whole bunch of those components right against each other in a tube with the same ID as the component rectangle (which would have to have a spring-loaded pusher at the opposite end from where the components exit the tube.  Except, of course, if any slack in the pusher ever developed, components in the tube would rotate, get flipped, get jammed or otherwise messed up.  So I guess I see why that didn't happen.  Sure would have been a lot more compact though![/font]
If I get you correctly you mean something like a bulletclip for automatic rifles, just stack m up and shove them out one by one. Replacing is just taking out the old clip inserting the new one instead of removing reels and peeling tape and so on and on. 
It should be possible for non emc components like resistors and capacitors.
But probably there is a risk the components will stick together, probably the reason they are individually packaged.

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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #75 on: May 10, 2016, 01:19:22 pm »
Quote from: Spikee on May 10, 2016, 12:59:03 pm
Regarding feeders. just put a camera above the pickup places (or a few) and just measure the rotation / location offsets while the head is moving.  Using this method something like the cheap neoden 4 feeders can be used.  No need for (ultra) precise >150$ feeders.

Or the other method:  Expose more than one component at a time, take picture, calculate offsets for them all (lets say 5 components) -> save those values -> pick and place.  When you know in software that 5 are placed you can just expose another 5 components and repeat the process.  This would be a mix between a tape pulling feeder and sticking component strips to the table.

Yes, the method I described previously (only necessary for tiny components) is to move then center the down-looking "nozzle camera" over the component before moving the nozzle over the component (the nozzle being a constant, known, fixed x and/or y distance from the "nozzle camera").  That's similar to what you say.

While this could indeed be elaborated to support 4 or 5 adjacent feeders, my tendency is to accept slower speed in exchange for lower cost, which means one nozzle... at least in the initial model of the machine.  But there would be nothing that prevents elaborating this to multiple nozzles if we came to understand that was appropriate for some reason (customer demand and willingness to pay for the enhancement).

I very much favor the KISS principle, as well as reducing complexity, parts count and cost as much as possible.  It appears rx8pilot agrees in principle about most of this too.

-----

As a separate but related issue:  A year or two ago I saw a youtube video of a DIY machine (I think) that lowered the nozzle onto the tape, then pulled the tape the appropriate distance by moving the nozzle head along the y axis, then raised the nozzle, moved the nozzle over the component (now where it belongs), lowered the nozzle onto the component, then raised the nozzle and component, then wandered off to place the component.

While that seems like a LOT of work to put on the pick-and-place machine to avoid the need to turn the tape sprocket, this certainly does eliminate some parts, totally eliminates the need for an electric or mechanical system (in the feeder or machine) to move the tape, and is very compatible with the approach I mentioned earlier in this message.

Anyone with comments about this should reply, since I don't have practical experience with feeders to judge this matter very effectively.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #76 on: May 10, 2016, 01:28:20 pm »
Quote from: Kjelt on May 10, 2016, 01:07:53 pm
Quote from: bootstrap on May 10, 2016, 12:53:40 pm
Now that you mention it, I don't see why they didn't just stack up a whole bunch of those components right against each other in a tube with the same ID as the component rectangle (which would have to have a spring-loaded pusher at the opposite end from where the components exit the tube.  Except, of course, if any slack in the pusher ever developed, components in the tube would rotate, get flipped, get jammed or otherwise messed up.  So I guess I see why that didn't happen.  Sure would have been a lot more compact though![/font]
If I get you correctly you mean something like a bullet-clip for automatic rifles, just stack m up and shove them out one by one.  Replacing is just taking out the old clip inserting the new one instead of removing reels and peeling tape and so on and on.

It should be possible for non emc components like resistors and capacitors.  But probably there is a risk the components will stick together, probably the reason they are individually packaged.

Yes, exactly correct.  I should have thought of that analogous example (the bullet-clip).

Yes, I was only thinking of this for caps, resistors, and maybe diodes and such that have rectangular bodies.  But the reasons we identified were probably too annoying to solve.  That, plus it is better, in general and when possible, to "do everything the same way", and apparently tape was compatible with that principle.

I'm not sure how many (if any) components fit this requirement, but maybe you can tell me.  How many tiny caps and resistors can be placed with any side of the package down on the PCB and still have the conductor on both ends against the solder-paste and PCB.  All?  Some?  Few?  None?  Since the tiny caps and resistors aren't polarized, if they can be placed on the PCB in any configuration, some kind of vibrating tub of components with rectangular recesses in a [rotating] disk at the bottom might capture individual components and rotate/feed them to an exit point.  But... while very compact... I feel we're biting off a new project and trying to re-invent the wheel without sufficient gain.
« Last Edit: May 10, 2016, 03:46:40 pm by bootstrap »
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #77 on: May 10, 2016, 01:38:24 pm »
I don't think it matters that much how the component is placed except with resistors >0402 you want to see the value on top.
Perhaps some capacitors that are not equally in width and height might want to be placed a particular way.
Anycase, just shortly going through this tesis (unfortunately i do not have the time) I noticed that in figure 4.1 on page30 that with a carousel shooter the components should be pre-processed on a feeder carriage, the turret heads stays static. Also in that same thesis interesting examples of other machines where the head only moves in the Y direction while the pcb moves in the X direction.
https://theses.lib.vt.edu/theses/available/etd-091599-123343/unrestricted/Complete_Thesis.pdf
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #78 on: May 10, 2016, 02:36:46 pm »
Quote from: rx8pilot on May 09, 2016, 11:51:46 pm

X/Y positioning is simple relative to the details of feeders, vision, nozzle changers, part release, pickup fault detection, fast part change over, tall parts, tube parts, etc are where things get challenging.  All of those challenges start getting in the way of other things and the machine gets crowded and complicated very quickly.  It seems that most discussions focus on the placement of the parts, where I would focus on how to deal with delivery and pickup of parts which where the real challenges are.

Well, I'm not sure x/y positioning is simple when that positioning needs to precise AND reliable AND repeatable on every machine you ship.  And by "reliable" I do NOT mean 1% errors like some folks in this forum seem to.  I'm not exactly sure what I mean, but I'm guessing something like 0.01% (1 out of 10,000... and that still seems much too high to me).

HOWEVER, I distinguish between errors that make the PCB "wrong" and those that "stop the process, BEEP loudly, and tell the operator what went wrong so he can fix the issue in a few seconds, then hit a "continue button".  These kinds of error cases I'm more accepting of, because they don't lead to bad PCBs.

Along these lines, the more "real world vision" a system has, the more errors can be detected and corrected automatically (or with loud beeps and operator notification and intervention, bypassed or compensated for without PCB errors).

For example, in the vision-heavy design I described previously, after the nozzle picks up a component, it moves to an up-looking "component camera".  If the nozzle failed to pick up the component, the software will easily be able to tell it is looking at an empty nozzle (without component) rather than a component on the nozzle.  So failures to pick up a component at the tape will be noticed.  This also catches the case where components are picked up [but not securely enough] and thus fall off when the nozzle accelerates and decelerates to place itself over the up-looking "component camera".  As long as there's no crucial mechanics or anything between the tape and [fixed] "component camera", the software can simply go back and grab another component and not worry so much about the lost component (unless it is expensive or otherwise problematic, in which case the machine can BEEP loudly to summon the operator).

The same principle applies to components placed on the PCB.  After a component is placed, the down-looking "nozzle camera" can move over the component and make sure the component is on the PCB in the position and orientation the component belongs (and didn't fall off the nozzle before it got over the final location (or something)).  Though the software can't be sure the component is precisely where it should be, it can certainly detect significantly offset or rotated components (due to component sliding or rotating on the nozzle tip due to bad vacuum seal between nozzle and component or other issue).

I don't have enough experience to anticipate every possible error case, but clearly vision approaches can be made able to detect errors and problems that systems without [as much] vision inherently cannot detect.


Quote
The PCB has fiducials and sits perfectly still the whole time.  In a practical sense, there is no concern for vision focus, flex, or temperature on the placement end of the process.

You may need to kick my butt... or perhaps my head... if I've become too enamored or impressed with the "PCB feeder mechanism" (or whatever it is called) on the neoden4.  The one that moves one PCB out of the working area and into a staging area (for operator pickup and inspection, or potentially directly onto the reflow-oven conveyor)... and then moves another empty PCB to where components can be placed on it.

Actually, having said that "out loud" (so to speak), I realize that I prefer not to support moving PCBs directly to the reflow-oven.  To do that implies a level of confidence that even I don't hope to achieve... like no errors of any kind on 99.999% of PCBs.  I think anything we hope to achieve here should be inspected by a vision system AND a human being before it is allowed to move on to the reflow-oven [conveyor].

Actually, having said that "out loud" (so to speak), it may be potentially feasible for a very, very, very advanced and heavily developed vision system program to automatically inspect the PCBs.  On first, second and third thought this seems absurd for our machine.  But on fourth thought, this is not completely beyond what MIGHT be practical EVENTUALLY.  The reason is, an algorithm that has the benefit of dozens if not hundreds of images of that same PCB that have been later verified as FULLY FUNCTIONAL == ERROR FREE could be leveraged into a fairly reliable vision system driven error detection process.

Having said all that, what I mean to say is, we almost certainly won't get that point by the time the machine is completed and on the market, but could possibly hope to achieve that "someday", and should therefore probably not design such capabilities OUT of the machine (design the machine in such a way that "PCB feeders" cannot be supported in the future).

Maybe you or others have comments about that.

Quote
The feeders, on the other hand, have a much more challenging task of moving the tapes to the exact position and picking up the parts without them flipping on end or diagonally.  The pickup part of the effort is where I have all of my problems - not putting the parts down.  Most (if not all) high-end machines put an enormous effort into the feeders to reduce the mis-picks to a very low number.  This effort makes the feeders very expensive and sophisticated.  In my case (and many other businesses like mine) we need a lot of feeders on the machine so saving money here is a way to drastically reduce the overall solution cost.

Unless you tell me otherwise, 99.9% of these problems occur with fairly tiny components (0805 and smaller).  True or False?

You see, one of the reasons I become even more sold on the vision approaches I've been advocating is precisely these kinds of feeder issues.  As I already described not far above in this message, the vision system I described way back on page 1 or page 2 of this topic (the message that lists the several steps in process A, B, C, D, E, F), vision makes it possible to at least DETECT mis-picked and dropped components (and take corrective actions), and perhaps more opportunities to remove the stringent burden and requirements on feeders that we haven't even recognized yet.  For sure the approach I described in that old message can assure the center of the nozzle tip comes down PRECISELY on the center of [tiny] components.  I have to assume the main reason components tip over and such is due to the center of the nozzle not being quite exactly over the center of the component.  True?

Quote
Also, feeder banks would be on my ideal machine so that I can be loading a job of 40 feeders while the machine is using 40 different feeders.  When it is time to switch - 2 banks of 20 feeders are swapped and ready in a minute, instead of loading each feeder one by one.  Each feeder should have a QR code or bar coded that allows the machine to identify it and associate the part that was loaded.  The QR code should be visible to the placement vision camera so it adds next to no cost at all.  The software (including offline software for setup) is where the codes get matched with the parts.

I very much agree with everything you say here about feeders and feeder banks, and swapping feeders and feeder-banks while the machine is placing components on PCBs from other feeders and feeder-banks.

And yes, we'd be CRAZY not to support something like the QR code.  That's something the down-looking "nozzle camera" should be able to read.  You should tell me what QR stands for, but I understand it to be a code that lets you know what components are on the installed reel.  Probably not the # of the component in the BOM, but something more general, right?

Having said all this, we definitely must be careful that accidental bumping and forces imposed by the operator while changing feeders and feeder-banks doesn't screw up any ongoing operations or processes, and doesn't make them less precise somehow (by bending, twisting, jiggling, vibrating or otherwise altering the fixed relationships of all the parts of the machine that need to stay in fixed relationships to work properly).  I worry about this a lot, because it is a typical kind of situation (from my experience) that can royally screw up a robotics device but not be detected.  Of course, I've never worked on a pick-and-place machine, but my past experiences with even sturdier devices than I imagine our machine raise a "caution flag" in front of me.


Quote
The placement speed is generally not a limitation in a small entry level environment - it is machine setup and parts management.  If I could have 40-60 parts in the machine on banks and swap out the banks in a minute or two to run a totally different job - the machine would be gold.  The feeders would have to be very clever to achieve the precision and the low-cost which would allow a working set and a standby set of feeders to swap super fast.

Yes, I'm willing to give up as much placement speed as we need to achieve other goals... unless it starts to get absurd (beyond 5x to 10x slower than low-end commercial machines that place 0201s and 0.50mm pitch).

To the rest of the above paragraph I say "damn straight".  And I more-or-less replied-to this part elsewhere.


Quote
I have made arc-second accurate positioners and very repeatable mounting fixtures for imaging (optical) - This is where I would put most of my efforts.  After a feeder/pickup scheme is developed - I would then move on to the XY gantry and other systems.

Sounds like you've worked with telescope systems before too!  That's how I originally got into everything I do.  I was totally hooked on space, astronomy, telescopes and related instrumentation by the time I was 8 years old.  The pursuit of that interest led to everything else.  Learning to program (my first program was an optical design and analysis program).  Learning to design optics (with my program).  Learning to develop microcomputers (to run my program and operate instrumentation and later automate telescopes and instrumentation).  Learn to write compilers to make my software faster.  Learn to fabricate diffraction limited optics (to build the optical systems I invented and designed).  Learn interferometers to design and fabricate my own optical testing equipment.  Learn photography and fancy darkroom techniques (to capture images of astronomical objects).  Learn image processing (to improve and extra information from these photos)... and I'm just getting started on how far that process has taken me.  It really is amazing to look back and that whole path, which I rarely do.  I've spent enormous quantities of time at astronomical observatories, including a 7 year stint as sole occupant of a remote self-sufficient mountaintop observatory.  Where I got absolute oodles of work and projects done, and totally cemented my hermit tendencies forever.

Anyway, if you want to tell me a bit about what aspects of optical systems you got into, that would be cool.[/font]
« Last Edit: May 10, 2016, 04:03:02 pm by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #79 on: May 10, 2016, 03:31:58 pm »
Quote from: Kjelt on May 10, 2016, 01:38:24 pm
I don't think it matters that much how the component is placed except with resistors >0402 you want to see the value on top.  Perhaps some capacitors that are not equally in width and height might want to be placed a particular way.
Any case, just shortly going through this thesis (unfortunately i do not have the time) I noticed that in figure 4.1 on page30 that with a carousel shooter the components should be pre-processed on a feeder carriage, the turret heads stays static.  Also in that same thesis interesting examples of other machines where the head only moves in the Y direction while the pcb moves in the X direction.  https://theses.lib.vt.edu/theses/available/etd-091599-123343/unrestricted/Complete_Thesis.pdf

Some thoughts page 30~33 or so remind me of...

The idea of moving the PCB in x and/or y instead of the "nozzle head" is interesting.  However, this just adds to the number of moving parts, because the nozzle head needs to move for other purposes (like go fetch components), so most likely the advantages of two independent motion systems are more than offset for our target market by increased cost and complexity.

These pages made me remember the first time I saw a youtube video of component shooters.  When I saw the PCB moving back and forth at high speed, I remember thinking "no freaking way would I depend on the acceleration to NOT move any component".  How fast "works [safely]" is a function of too many variables, including two or three characteristics of the solder paste, how firmly the component was pushed into the solder paste, the mass of the component, the area of the component [pads] in contact with the solder paste, and more.  I remember saying to myself "this kid doesn't want to design a machine like that, with all those complexities and potential failure modes".  I did see in the pages that the acceleration of the PCB table is variable, and changed to stay below the computed "maximum acceleration" value of the worst case component currently on the PCB.

Those shooter machines are definitely impressive, but not where I'm coming from (or going to).
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #80 on: May 10, 2016, 04:37:56 pm »
Some notes from experience:
Don't F*** around trying to use vias as fiducials. I have tried, and it sucks. Via placements are based on the signals - not geometry correction. Many have traces coming from them which distorts the geometric center. Most are in the the wrong place. None of them are ID'd with the silkscreen. It takes seconds to drop proper fids on a layout that are marked, have perfect geometry, and are optimized to get the best geometric corrections. Simple. All the talk about scanning the PCB and looking at pad with paste, etc is senseless. The machine I use is ANCIENT and with 3 well placed fiducials can nail .4mm and 0201 every single time without fail. A modern vision system, even a simple one, can outperform it. You are solving a problem that does not exist. I did have to use some old boards where only vias and other holes were available, and it was a lot worse. It worked well enough to get through the batch, but I simply added real fids on the next run and have not had a single alignment issue even with the fine pitch stuff.

Like I said earlier - placing the part is FAR easier than picking it up in the first place. Feeders are the bigger challenge. The idea of using a camera to correct for poor part presentation on a feeder is not always going to work either. A SOD523 diode is black on glossy black plastic tape with a tiny pickup area. A camera may struggle with figuring that one out, at best it would be slow and at worse it would fail to pick-up correctly. The most proper long term solution is to have a precision indexing feeder IMHO - maybe use the camera during setup to get an offset.

My ideas on how to design a machine have changed substantially after I got a machine, repaired it and started using it for real work on fine pitch PCB's. I have a far more clear understanding of the challenge because I have met the challenge. If I designed a PnP machine a year ago, I doubt it would be very good, if I designed it today - it would be far better and take a lot less time. I suspect I would mimic a lot of how my own Quad machine is setup but with modern motion control and vision - making it a much simpler machine. The side scanner is the best feature - it uses a laser/line scanner to image the side of the part while rotating to get it's orientation while in motion. It is very reliable and can be used for nearly all parts. Every single part is vision aligned, but without stopping. There is also an up facing camera for very fine pitch BGA's but I rarely use it in practice since the spin alignment works so well. Keep in mind this is a decades old machine and it works quite well in that regard. A modern 'clone' of a Quad IV-C would be a fantastic starter machine and the engineering effort would be far, far less than going from scratch and learning the dirty details of every single sub-system.


What does not work is if the feeders over/underfeed and the nozzle grabs the edge of the part. It will be picked up at an oblique angle and the alignment will fail. The part has to be in a predictable location to be picked up correctly - after that things are easy and very predictable.

If you make a $10k machine that mis-picks and requires constant supervision and possibly re-work - it will be more expensive than a very reliable $20k machine to even a small business like mine. Most business owners know the value of time and will be sensitive to that. Another thing that takes a lot of labor money is machine setup. To be viable - it really needs to be easy to setup and intuitive to operate. This includes recovering from mistakes, mis-picks, etc. The long discussion about precision and advanced imaging says nothing at all about what it will be like to setup and operate the machine when a deadline is looming. I will maintain that the placement effort is easy and should not be the initial focus of any design effort.

Ask yourself what are the problems you are trying to solve:

Cost?
Fine pitch placements?
FAST setup/changover?
Reliability?
Size?
Component mix?
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #81 on: May 10, 2016, 05:06:49 pm »
Quote from: rx8pilot on May 10, 2016, 04:37:56 pm
The most proper long term solution is to have a precision indexing feeder IMHO - maybe use the camera during setup to get an offset.
What you can do pretty much "for free" is look for consistent offsets during vision and use this to home in on the optimum pick posiiton.
Quote
My ideas on how to design a machine have changed substantially after I got a machine, repaired it and started using it for real work on fine pitch PCB's. I have a far more clear understanding of the challenge because I have met the challenge.
Couldn't agree more. Anyone trying  to design a pick & place who hasn't got  experience using will never make a good job of it.
It's one of those problems where the basic priciples are very simple, but it's all in a huge number of little details.

 
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #82 on: May 10, 2016, 05:27:45 pm »
Quote from: mikeselectricstuff on May 10, 2016, 05:06:49 pm
What you can do pretty much "for free" is look for consistent offsets during vision and use this to home in on the optimum pick posiiton.

Not a bad idea to average the feeder error over the course of many picks, is that what you are suggesting? My machine has standard feeders that are good for 0603 and larger. There are also precision feeders that can go for 0201 and maybe 1005. After a number of repairs, I have considered how they could be simplified. There are quite a few options for simplification that I do not believe would compromise the positioning repeatability.

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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #83 on: May 10, 2016, 05:42:39 pm »
Quote from: rx8pilot on May 10, 2016, 05:27:45 pm
Quote from: mikeselectricstuff on May 10, 2016, 05:06:49 pm
What you can do pretty much "for free" is look for consistent offsets during vision and use this to home in on the optimum pick posiiton.

Not a bad idea to average the feeder error over the course of many picks, is that what you are suggesting?
Yes, this is what my machine does. Obviously relies on feeder errors being consistent, but should help keep as much margin as possible to deal with random errors. For the really small parts, unless you have hi-res downward vision, probably the only sensible way to derive the exact pick centre position is like this.
 
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #84 on: May 10, 2016, 06:01:13 pm »
Quote from: bootstrap on May 10, 2016, 03:31:58 pm
The idea of moving the PCB in x and/or y instead of the "nozzle head" is interesting. 
How about moving the nozzle head AND the pcb both in x and y direction?
Crazy? Expensive? Bear with me.
If you want a movement accuracy (step) of lets say 0,01mm this is going to cost you big time if you have larges axis of 600mm or so or will be slooooooooooow (gearbox).
But if the pcb for example only has to move 10mm in X or Y then a 0,01mm accuracy is easy and cheap with a simple stepper motor with gearbox.
So the large movements you do cheap and reasonable accurate like 0,1 mm or so and the last correction is the pcb table with 0,01mm.
You could even go so far to use what in cnc land is called a 4th axis and that is to rotate the pcb slightly for extremely small corrections, therefore making the nozzlehead rotational stepper cheaper / lighter.
Just an out of the box thought, we are brainstorming.  :)
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Re: New Pick and Place design ideas
« Reply #85 on: May 10, 2016, 06:12:10 pm »
There are machines that do this (I think) and it has at least two problems. The first is that it adds substantial complexity which will increase cost and reduce reliability. To overcome the reliability hit, the cost can be increased even more. The second is that PCB's with heavy parts can be disturbed by the rapid movements.

I would be looking for the lowest part count and fewest sources of oops as possible. Adding an additional coordinated X/Y stage would have me frazzled from the beginning. At this price point - super speed is not a driving factor over reliability, cost, and ease of use.
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #86 on: May 10, 2016, 06:36:19 pm »
its not about the speed it is about the accuracy and reducing the costs.
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Re: New Pick and Place design ideas
« Reply #87 on: May 10, 2016, 06:57:48 pm »
Just as an educated guess - I would not expect that approach to be lower cost when compared to a well designed motion system.
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Offline Koen

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Re: New Pick and Place design ideas
« Reply #88 on: May 10, 2016, 07:39:18 pm »
I agree with Mike and Carlos. Don't go all-in on your first machine. At least, visit an assembly shop, talk with the guys loading it, ask yourself why the engineers of this industry aren't doing it your way, ask yourself why you think your way is better and so on.

One often overlooked point and a simple red flag to readers in DIY CNC machines projects, whatever they are, is the lack of interest for metrology. Dudes are always going to build machines precise to 0.01mm but have never heard of a dial indicator or ignore the price of a long-enough reference plane or use an out-of-class measurement device or have no clue how awful it is to align 3 axis with each other, let-alone 5.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #89 on: May 10, 2016, 07:56:30 pm »
Quote from: rx8pilot on May 10, 2016, 04:37:56 pm
Some notes from experience:
Don't F*** around trying to use vias as fiducials.  I have tried, and it sucks.  Via placements are based on the signals - not geometry correction.  Many have traces coming from them which distorts the geometric center.  Most are in the the wrong place.  None of them are ID'd with the silkscreen.  It takes seconds to drop proper fids on a layout that are marked, have perfect geometry, and are optimized to get the best geometric corrections.  Simple.  All the talk about scanning the PCB and looking at pad with paste, etc is senseless.  The machine I use is ANCIENT and with 3 well placed fiducials can nail .4mm and 0201 every single time without fail.  A modern vision system, even a simple one, can outperform it.  You are solving a problem that does not exist.  I did have to use some old boards where only vias and other holes were available, and it was a lot worse.  It worked well enough to get through the batch, but I simply added real fids on the next run and have not had a single alignment issue even with the fine pitch stuff.

Like I said earlier - placing the part is FAR easier than picking it up in the first place.  Feeders are the bigger challenge. The idea of using a camera to correct for poor part presentation on a feeder is not always going to work either.
A SOD523 diode is black on glossy black plastic tape with a tiny pickup area.  A camera may struggle with figuring that one out, at best it would be slow and at worse it would fail to pick-up correctly.  The most proper long term solution is to have a precision indexing feeder IMHO - maybe use the camera during setup to get an offset.

My ideas on how to design a machine have changed substantially after I got a machine, repaired it and started using it for real work on fine pitch PCB's.  I have a far more clear understanding of the challenge because I have met the challenge.  If I designed a PnP machine a year ago, I doubt it would be very good, if I designed it today - it would be far better and take a lot less time.  I suspect I would mimic a lot of how my own Quad machine is setup but with modern motion control and vision - making it a much simpler machine.  The side scanner is the best feature - it uses a laser/line scanner to image the side of the part while rotating to get it's orientation while in motion.  It is very reliable and can be used for nearly all parts.  Every single part is vision aligned, but without stopping. There is also an up facing camera for very fine pitch BGA's but I rarely use it in practice since the spin alignment works so well.  Keep in mind this is a decades old machine and it works quite well in that regard.  A modern 'clone' of a Quad IV-C would be a fantastic starter machine and the engineering effort would be far, far less than going from scratch and learning the dirty details of every single sub-system.


What does not work is if the feeders over/underfeed and the nozzle grabs the edge of the part. It will be picked up at an oblique angle and the alignment will fail. The part has to be in a predictable location to be picked up correctly - after that things are easy and very predictable.

If you make a $10k machine that mis-picks and requires constant supervision and possibly re-work - it will be more expensive than a very reliable $20k machine to even a small business like mine.  Most business owners know the value of time and will be sensitive to that.  Another thing that takes a lot of labor money is machine setup.  To be viable - it really needs to be easy to setup and intuitive to operate.  This includes recovering from mistakes, mis-picks, etc.  The long discussion about precision and advanced imaging says nothing at all about what it will be like to setup and operate the machine when a deadline is looming.  I will maintain that the placement effort is easy and should not be the initial focus of any design effort.

Ask yourself what are the problems you are trying to solve:

Cost?
Fine pitch placements?
FAST setup/changover?
Reliability?
Size?
Component mix?

Hahaha.  Okay, I just deleted "via pads" from the business plan!  Besides, the more we discussed this issue, the more clear it became we don't really need them anyway.

About the case of "black component on black tape" (or "white component on white tape").  How do seriously professional feeders that can absolutely, positively move the tape EXACTLY the appropriate distance every time... make sure they can pick up the FIRST of those components after the reel is loaded (to get in sync)?

That laser component alignment.  I assume that's doing the same job as those "jaws" in the LE40V videos that I posted links to a while back, correct?

I assume that laser alignment means the part gets rotated until the reflection off the side of the component comes back into the open slit (in to a photodiode) under the laser illuminated slit just above... or something like that.  If not, explain how that works.

Another minor detail that is probably irrelevant.  Those "jaws" that do component alignment also center the component on the nozzle, but I assume the laser setup doesn't do anything mechanical except rotate the nozzle and component to align the edges.  Correct?

When you say "precision indexing feeder", does that basically come down to the ability to rotate the sprocket that pulls the tape by very precise rotational increments (in other words, a high-count encoder (or stepper) and ways to assure backlash and such isn't happening?

ABSOLUTELY YES to the notion that a $20K machine that works, and works reliably, precisely and intuitively is infinitely better than a $10K machine that isn't reliable, that isn't precise, that isn't intuitive, or combinations of these.  OTOH, if we can get all that in a $10K (or much more likely $15K) machine (including feeders), then that's fine with me.  But I very much resist going over $20K in any event.  If the selling price goes above $20K, I say "we failed" (just as surely as if the price was $10K but had problems).

I do worry a bit about your next comments.  You make it sound like we're making a machine that fully competes on all bases with $100K machines (or at least $40K machines like the ddmnovastar LE40V), including on the basis of speed.  I don't think we are likely to be able to do that.  HOWEVER, while I believe we won't match their placement speed, we may be able to beat the speed, efficiency and convenience of setup for a job, and switching from job to job.  So "all things considered" we might end up faster... and doing so is a very good goal to set for ourselves, I think.

I'm not saying we couldn't beat their pick-and-place speed.  We could.  I've done very high-performance servo systems with pancake motors, which are totally awesome motors (virtually zero inductance and no cogging so tiny increments of rotation are possible and thus huge dynamic range of practical speeds), and we could knock their socks off speed wise... but then our machine will not be in the same price niche.  As I said elsewhere, I pretty much NEVER want to compete head to head with anyone... ever.  I want to be the only viable player in our niche.

Requirements important to me:

#1:  mandatory:  reliably places tiny (<= 0201) and fine-pitch (<= 0.50mm) components.
#2:  mandatory:  price is $10K to $20K with a reasonable set of feeders.
#3:  mandatory:  reliable and repeatable for every machine shipped.
#4:  important:    fast, reliable, convenient job setup and change.
#5:  convenient:  unlimited component mix.
#6:  no biggie:     fast part placement.
#7:  no biggie:     small machine size.
#8:

Actually, I don't really know what you meant by "component mix".  Please explain your exact meaning.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #90 on: May 10, 2016, 08:05:17 pm »
Quote from: mikeselectricstuff on May 10, 2016, 05:06:49 pm
Quote from: rx8pilot on May 10, 2016, 04:37:56 pm
The most proper long term solution is to have a precision indexing feeder IMHO - maybe use the camera during setup to get an offset.

What you can do pretty much "for free" is look for consistent offsets during vision and use this to home in on the optimum pick posiiton.

Quote
My ideas on how to design a machine have changed substantially after I got a machine, repaired it and started using it for real work on fine pitch PCB's. I have a far more clear understanding of the challenge because I have met the challenge.

Couldn't agree more.  Anyone trying  to design a pick & place who hasn't got  experience using will never make a good job of it.  It's one of those problems where the basic principles are very simple, but it's all in a huge number of little details.

That's why here in this forum, because the practical experience with actually running a PCB assembly line with pick-and-place is helping me a lot.  Nonetheless, I've creating machines, devices and processes that never existed before and are much more complex than a pick-and-place machine, so nobody in the universe had any experience before I designed and implemented the machine or device, and the results were more than satisfactory.  So I'm not quite as pessimistic as you, especially with advice and help with people who have been through the whole process (multiple times).  Nonetheless, I'm not saying it is easy, and I'm not saying the absolute first item built won't be tested, tweaked, modified and tested more before anyone even considers "production".

But maybe we'll support a couple alpha and beta testers...     |O     :box:     :-DD

And you'll be more than welcome to say "told you so"... if it comes to that.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #91 on: May 10, 2016, 08:22:35 pm »
Quote from: Kjelt on May 10, 2016, 06:01:13 pm
Quote from: bootstrap on May 10, 2016, 03:31:58 pm
The idea of moving the PCB in x and/or y instead of the "nozzle head" is interesting. 
How about moving the nozzle head AND the pcb both in x and y direction?  Crazy? Expensive? Bear with me.

If you want a movement accuracy (step) of lets say 0,01mm this is going to cost you big time if you have larges axis of 600mm or so or will be slooooooooooow (gearbox).  But if the PCB for example only has to move 10mm in X or Y then a 0,01mm accuracy is easy and cheap with a simple stepper motor with gearbox.  So the large movements you do cheap and reasonable accurate like 0.10 mm or so and the last correction is the pcb table with 0.01mm.

You could even go so far to use what in cnc land is called a 4th axis and that is to rotate the PCB slightly for extremely small corrections, therefore making the nozzle-head rotational stepper cheaper / lighter.

Just an out of the box thought, we are brainstorming.  :)

I agree with all this, but as with several issues, "the devil is in the details" (of the design, mostly).

One really nice thing about moving the PCB around in x,y is... the PCB has little mass.  Moving a PCB around in x,y doesn't require large forces (even to move fairly quickly).  However, as I mentioned elsewhere, the notion of moving the PCB around makes me a bit nervous.  Yes, yes, I know.  I've seen the videos of those FTL "component shooters" on youtube, and the PCB is moving around like crazy.  And obviously they are reliable.  So this is one of those uncomfortable cases where "others prove this works reliably", but my gut won't stop raising the "warning flag".  For example, maybe they have air bearings or something to prevent vibration.  True, in principle, vibration won't matter either, because the solder paste the components are sitting on is viscous and will absorb jitter and vibrations.  So my mind says "yeah, it is proven to work", but my gut (from experience) says... this may be a trap!

And as you say, in this scheme (assuming the vision techniques are applied), the x,y mechanics that drive the "nozzle head" + "nozzle camera" around don't need to be precise, just smooth and stable.

This is worth considering further... with care.  I'm not convinced, and I'm not unconvinced... yet.  But we'd have to become convinced that total cost and complexity is not increased, which seems unlikely.
« Last Edit: May 10, 2016, 08:24:51 pm by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #92 on: May 10, 2016, 08:27:35 pm »
Quote from: rx8pilot on May 10, 2016, 06:57:48 pm
Just as an educated guess - I would not expect that approach to be lower cost when compared to a well designed motion system.

That's my educated guess too.  But given the fact the larger moving x,y stage doesn't need to be as precise, I can't yet convincingly prove to myself that approach is worse.  But I remain fairly confident my educated guess (and yours) is correct.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #93 on: May 10, 2016, 08:36:02 pm »
Quote from: Koen on May 10, 2016, 07:39:18 pm
I agree with Mike and Carlos. Don't go all-in on your first machine.  At least, visit an assembly shop, talk with the guys loading it, ask yourself why the engineers of this industry aren't doing it your way, ask yourself why you think your way is better and so on.

One often overlooked point and a simple red flag to readers in DIY CNC machines projects, whatever they are, is the lack of interest for metrology.  Dudes are always going to build machines precise to 0.01mm but have never heard of a dial indicator or ignore the price of a long-enough reference plane or use an out-of-class measurement device or have no clue how awful it is to align 3 axis with each other, let-alone 5.

I know where you're coming from.  Believe me, I would be more skeptical that the skeptics posting in this topic if 99.99% of the population tried this project.  However, it appears to me that at least two of us have decades of experience with super-precise mechanical systems, have been through the machine design ringer several times, beaten to pulp repeatedly, and learned a few lessons (and better intuition) during our ordeals.  I believe that raises our chances dramatically.

It better, otherwise we're toast!

Of course, you have no way to know for sure whether I'm totally full of crap or not, and I don't know whether you know anything concrete about rx8pilot or "other optimists" who posted in this topic either.  So from your perspective, maybe you should be even more skeptical than you already are!  Hmmm.  Which side am I on here?   :scared:
« Last Edit: May 10, 2016, 09:05:17 pm by bootstrap »
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #94 on: May 10, 2016, 08:37:09 pm »
Quote
Hahaha.  Okay, I just deleted "via pads" from the business plan!  Besides, the more we discussed this issue, the more clear it became we don't really need them anyway.

in your business plan have you included hiring some folks who wont' scare your customers?
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Re: New Pick and Place design ideas
« Reply #95 on: May 10, 2016, 08:40:57 pm »
Quote from: bootstrap on May 10, 2016, 07:56:30 pm

About the case of "black component on black tape" (or "white component on white tape").  How do seriously professional feeders that can absolutely, positively move the tape EXACTLY the appropriate distance every time... make sure they can pick up the FIRST of those components after the reel is loaded (to get in sync)?

On my machine, there are two options. When you load the tape, you can visually verify the part is aligned with a fixed index mark. That works well for bigger parts like 0805 and up. You can also set a camera assisted coordinate offset to compensate for any strangeness in the feeder. After that, you are counting on it's ability to move the tape very repeatable step 2mm, 4mm, 8mm, 12mm, etc. Every time you send the head back to that feeder - the next part should be exactly where the previous one was before. It's all about repeat-ability with various tapes. There are thick paper tapes and very thin plastic tapes. On the 'precision' feeders, the mechanical slot keeps some lateral pressure on the tape to prevent 'gate weave' and the indexing system is substantially more precise - brushless servo system instead of a DC motor and a 4 count encoder. Those feeders nearly eliminate mis-picks entirely - but they are much more expensive.

Quote from: bootstrap on May 10, 2016, 07:56:30 pm

That laser component alignment.  I assume that's doing the same job as those "jaws" in the LE40V videos that I posted links to a while back, correct?

I assume that laser alignment means the part gets rotated until the reflection off the side of the component comes back into the open slit (in to a photodiode) under the laser illuminated slit just above... or something like that.  If not, explain how that works.

The laser is on one side of the head and the line camera on the other. What it is looking at is the shadow of the part - the outer perimeter. When a nozzle is loaded, it uses this system to determine the nozzle length to verify it loaded properly. It can also tell what nozzle in loaded by looking at the profile. When it picks a part - it knows the orientation roughly, but this system allows it to detect X,Y,T errors related to the pickup. As the part rotates, it can see it getting wider/narrower making it easy to figure out when it is square. Also, that process delivers X/Y dimensions that are compared to the expected part so it will stop if it picks up something the wrong size or shape. It does all of this while it is moving to the place location and integrates the errors with the placement data and the X,Y, Skew data derived from the fiducials. DDM uses a mechanical squaring mechanism which is totally different and I doubt it is as accurate. I cannot say for sure because I have never used it though.

Quote from: bootstrap on May 10, 2016, 07:56:30 pm
Actually, I don't really know what you meant by "component mix".  Please explain your exact meaning.[/font]

The component mix is the variety you have to place. I have to do a big inductor, followed by .4mm QFN, followed by SOIC's in tubes, 44pin QFP's, 10mm CAN's, 0402 passives, etc. Usually have at least 80 unique parts loaded at any given moment - sometimes 100+. Project mix would be needing to switch to different PCB's with different parts - that is where there is commonly a major time penalty. Loading feeders, figuring out where they are, verifying part orientation, etc. The reason I keep a lot of part loaded in the machine is because it allows me to switch boards by just calling up a new program and maybe 1-2 feeders change. Most of the low cost machines cannot hold anywhere near that many parts so every switch over is a much bigger chore.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #96 on: May 10, 2016, 08:46:02 pm »
Quote from: mrpackethead on May 10, 2016, 08:37:09 pm
Quote
Hahaha.  Okay, I just deleted "via pads" from the business plan!  Besides, the more we discussed this issue, the more clear it became we don't really need them anyway.

in your business plan have you included hiring some folks who wont' scare your customers?

Nope.  No need.  Our satisfied customers [and website] are our representatives and salespeople.

Put up a website.  Post a slew of cool videos on youtube showing the machine in action.  Send a few demo units out.  Get a few positive reviews.  Post them and pass them around the internet.  Place notices in forums like this (and not very much like this) that link and point to the above.

Then... accept whatever happens, whether that's zero or terminal back-order syndrome.  I don't consider this a huge business potential, only modest.  The biz/company has to be even simpler and more streamlined than the machine!

Not sure what rx8pilot has in mind as far as the biz, but my sights are quite modest.  Maybe 25 units the first year, 50 the second, 100 the third, and never much more than 100~200 per year.  That's no empire, and given the lower price, that's not big honking corporation (which is a huge positive in my mind).  Nonetheless, 100 units * $10K profit each ($1M per year) isn't chump change either (for two people, plus maybe a couple inexpensive helpers).

OTOH, we are WAY too early to be thinking seriously about this!

PS:  My annoying personality may not be too terrible in the role of temporary tech support (for short term), since my main failure is getting right to the point and placing my entire focus on the technical issues... and getting them right.  For people who just want to get their damn machine going the way they want, maybe my apparently crappy social skills are a perfect match.  Or maybe not.  In which case I'll go hide and work, which is my plan anyway.  Let happy customers show their appreciation by helping newbies and fellow adopters with questions and problems.  My goal is... they don't need us after they receive the machine.

Oh, plus the way I think, we'll probably end up trading someone who really wants but can't afford even $20K a "free machine" in exchange for handling all our support.  To "pay with product" is a great approach in my experience.
« Last Edit: May 10, 2016, 08:59:40 pm by bootstrap »
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #97 on: May 10, 2016, 09:01:47 pm »
Quote from: bootstrap on May 10, 2016, 08:46:02 pm
Nonetheless, 100 units * $10K profit each ($1M per year) isn't chump change either (for two people, plus maybe a couple inexpensive helpers).

I though this was a $10k machine? I can't see it as a big business either so not really motivated to go anywhere with it. If it turned out to be a big business for whatever weird reason - it would be immediately copied by 5 companies in China for a lot less $ and the low-cost seeking customers we are catering to would jump ship faster than you can say 'Fine Pitch Placement'. If there was $10k gross profit in each machine, a huge amount of that would be eaten by trade shows, marketing, service/support, supply chain problems, inventory tracking, build-out of the new building needed, and all the other expenses that are part of modern business. The bigger the profits, the bigger the challenge to keep competitors away - which costs more money. Not trying to be negative, just not seeing a reason to jump off a cliff with hopes the Pick and Place machine would somehow create a parachute.

End of business plan.  :-DD

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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #98 on: May 10, 2016, 09:22:43 pm »
Quote from: rx8pilot on May 10, 2016, 08:40:57 pm
Quote from: bootstrap on May 10, 2016, 07:56:30 pm

About the case of "black component on black tape" (or "white component on white tape").  How do seriously professional feeders that can absolutely, positively move the tape EXACTLY the appropriate distance every time... make sure they can pick up the FIRST of those components after the reel is loaded (to get in sync)?

On my machine, there are two options. When you load the tape, you can visually verify the part is aligned with a fixed index mark.  That works well for bigger parts like 0805 and up.  You can also set a camera assisted coordinate offset to compensate for any strangeness in the feeder.  After that, you are counting on it's ability to move the tape very repeatable step 2mm, 4mm, 8mm, 12mm, etc.  Every time you send the head back to that feeder - the next part should be exactly where the previous one was before.  It's all about repeat-ability with various tapes.  There are thick paper tapes and very thin plastic tapes.  On the 'precision' feeders, the mechanical slot keeps some lateral pressure on the tape to prevent 'gate weave' and the indexing system is substantially more precise - brushless servo system instead of a DC motor and a 4 count encoder.  Those feeders nearly eliminate mis-picks entirely - but they are much more expensive.

You are increasingly convincing me that checking the position of tiny components with the down-looking "nozzle camera" before moving to pick them up... is the safe and reliable way to go.  However, note that each time it finds the component with the camera, it detects (and remembers) the error.  After a few picks of a given tiny component the software should be able to tell whether it can continue without pre-checking with the camera, or needs to check every single time.  Frankly, my money is on "check every single time anyway" for all tiny components.  At the margins (perhaps 0805) it will become clear the mechanical precision is sufficient and camera checking is a total waste of time.

Quote
Quote from: bootstrap on May 10, 2016, 07:56:30 pm
That laser component alignment.  I assume that's doing the same job as those "jaws" in the LE40V videos that I posted links to a while back, correct?

I assume that laser alignment means the part gets rotated until the reflection off the side of the component comes back into the open slit (in to a photodiode) under the laser illuminated slit just above... or something like that.  If not, explain how that works.

The laser is on one side of the head and the line camera on the other.  What it is looking at is the shadow of the part - the outer perimeter.  When a nozzle is loaded, it uses this system to determine the nozzle length to verify it loaded properly.  It can also tell what nozzle in loaded by looking at the profile.  When it picks a part - it knows the orientation roughly, but this system allows it to detect X,Y,T errors related to the pickup.  As the part rotates, it can see it getting wider/narrower making it easy to figure out when it is square.  Also, that process delivers X/Y dimensions that are compared to the expected part so it will stop if it picks up something the wrong size or shape.  It does all of this while it is moving to the place location and integrates the errors with the placement data and the X,Y, Skew data derived from the fiducials.  DDM uses a mechanical squaring mechanism which is totally different and I doubt it is as accurate.  I cannot say for sure because I have never used it though.

The old "Platos components" approach, eh?  Of course (yet again), when the up-looking "component camera" takes an image of the component on the nozzle, it can determine the rotation fairly accurately.  The resolution of this camera can be twice as good as the others, since it probably only needs to examine 2" square components, not 4" diameter.

Quote
Quote from: bootstrap on May 10, 2016, 07:56:30 pm
Actually, I don't really know what you meant by "component mix".  Please explain your exact meaning.

The component mix is the variety you have to place.  I have to do a big inductor, followed by 0.4mm QFN, followed by SOIC's in tubes, 44pin QFP's, 10mm CAN's, 0402 passives, etc.  Usually have at least 80 unique parts loaded at any given moment - sometimes 100+.  Project mix would be needing to switch to different PCB's with different parts - that is where there is commonly a major time penalty.  Loading feeders, figuring out where they are, verifying part orientation, etc.  The reason I keep a lot of part loaded in the machine is because it allows me to switch boards by just calling up a new program and maybe 1-2 feeders change.  Most of the low cost machines cannot hold anywhere near that many parts so every switch over is a much bigger chore.

I hope there is no reason we can't have the machine place all of the first component (probably the smallest), then place all the next component (next to smallest), then so forth.  This has many advantages, which we can discuss later (here or by voice).
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #99 on: May 10, 2016, 09:34:33 pm »
Quote from: rx8pilot on May 10, 2016, 09:01:47 pm
Quote from: bootstrap on May 10, 2016, 08:46:02 pm
Nonetheless, 100 units * $10K profit each ($1M per year) isn't chump change either (for two people, plus maybe a couple inexpensive helpers).

I thought this was a $10k machine?  I can't see it as a big business either so not really motivated to go anywhere with it.  If it turned out to be a big business for whatever weird reason - it would be immediately copied by 5 companies in China for a lot less $ and the low-cost seeking customers we are catering to would jump ship faster than you can say 'Fine Pitch Placement'.  If there was $10k gross profit in each machine, a huge amount of that would be eaten by trade shows, marketing, service/support, supply chain problems, inventory tracking, build-out of the new building needed, and all the other expenses that are part of modern business.  The bigger the profits, the bigger the challenge to keep competitors away - which costs more money.  Not trying to be negative, just not seeing a reason to jump off a cliff with hopes the Pick and Place machine would somehow create a parachute.

End of business plan.  :-DD

The way I figure it, those are the numbers for a $20K machine.  But if we actually achieve a $10K target price, we'll sell twice as many, making the total profit the same in both cases.

Make sense?

This IS back of the envelope time, after all!

I know everything I say that is "unconventional" scares most people.  But I started a couple of the kind of unconventionally simple "mean, clean, minimalist machine" companies before that had a total of one owner-worker-employee plus one grunt-employee... and it worked great.  No physical store.  No physical factory.  No physical buildings at all.  All "work at home".  Assemble the PCBs and mechanics at home, but the mechanical parts were all subcontracted (and assembled and shipped from home).

What about China?  I thought that's where we'd have our machines made!  How can someone else in China make it any cheaper than us, when we have zero overhead?

If you want to waste your time going to trade shows and all that jazz... be my guest.  No need, at least not after the first year.  Either that, or we make our tech-slave guy who does our tech support in exchange for his free personal machine... also do any important trade shows (if any exist after the first year and word-of-mouth gets going).

Marketing budget == zero.  Free new product announcements... yes.  Free forum posts and comments... yes.

Buildings == zero.  Not even rent.  Work from home, dude!  Products made in China and drop-shipped like neoden4.

SCREW MODERN BUSINESS.  Be a futuristic business or die.

Oh, and most of that millions bucks profit per year is for your/our time!  Expenses?  Near zero.

Conventional business is INSANE.  Where do you think amazon would be today if they opened a conventional bookstore?  OUT OF BUSINESS.

Here is one less dramatic point that's nonetheless true.  The first n units you produce cost ZERO to market.  People find out via free product announcements in trade publications, articles, blogs, forums, web-sites and internet communication.  This is  what I call the "natural market size".

To attempt to double your "natural market size" in conventional ways, you must spend so much that ALL OR MORE THAN your extra "profits" earned are consumed by the expenses you incur to push your sales to double.  WHICH MEANS YOU GOT NOTHING OR LESS FOR THE EFFORT.  Yet, 99.99% of marketing geniuses will never learn this or know this.  And nobody tries anything unconventional, so they never find out!  That's how almost everything works on planet earth.  Humans are clueless, terrified pinheads!

Almost everyone wants to be "king of the world"... and almost all of them end up defeating themselves by chasing that absurd and almost always unrealistic goal.  KISS.  And KINS (keep it natural, stupid).

Thought I coulda, woulda, shoulda been a billionaire.  And now I'm destitute because I wasn't satisfied being a millionaire!

« Last Edit: May 11, 2016, 05:21:41 am by bootstrap »
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #100 on: May 10, 2016, 10:29:47 pm »
Quote from: bootstrap on May 10, 2016, 09:22:43 pm

You are increasingly convincing me that checking the position of tiny components with the down-looking "nozzle camera" before moving to pick them up... is the safe and reliable way to go.  However, note that each time it finds the component with the camera, it detects (and remembers) the error.  After a few picks of a given tiny component the software should be able to tell whether it can continue without pre-checking with the camera, or needs to check every single time.  Frankly, my money is on "check every single time anyway" for all tiny components.  At the margins (perhaps 0805) it will become clear the mechanical precision is sufficient and camera checking is a total waste of time.

The process of picking the part will move it, so using vision on the feeder will not give you what you need to place the part - at least not with the sensitive ones. Again, not all parts are vision candidates while they are in the tape. That is why each part is scanned after it is picked up and stable. The XYT correction is different each time.


Quote from: bootstrap on May 10, 2016, 09:34:33 pm
SCREW MODERN BUSINESS.  Be a futuristic business or die.

Oh, and most of that millions bucks profit per year is for your/our time!  Expenses?  Near zero.

I am about as unconventional and forward thinking as they come. I have built an entire factory into a 400ft/2 garage that I call 'Factory 400'. I produce more at my my house than I did when i had a partner that hired a dozen people and had 5000ft/2. I am very automation centric as well as process oriented. That is not why I would not go for a PnP business. It's because I have at least the same or better chance of turning my current products into a $million profit. I am already on the market and selling right now, so I have only a trickle of R&D and the business is already in motion - building.

Expenses are not zero unless you are stealing all the materials, tools, and supplies and live on nothing. Let's say we formed a business and it took a year to develop. The costs would be anything but trivial - prototyping a myriad of mechanics, wiring harnesses, PCB's, software, burning things up, starting over, etc. Let's pretend it takes 4 full iterations to get a reliable enough system to release (generous estimate) and then we get to the end of the R&D year and need to do a pilot run of 15 systems - 5 of which are demos. That is a lot of money that is needed up front. Now, pretend we sell the first 10 units for a gross profit of $10k ea - that may cover 1/4 of our expenses if we are lucky - but there will be issues that we have to cover for free on the early adopter units and hope they are nice enough to promote the product. I doubt that forums that cater to hobbyists will be a great sales tool for a $20k assembly tool that is only needed if you are a full fledged business of just the right size and type. Tiny business can't afford it, larger businesses would want to outsource high volume or buy a much more capable machine. A niche within a niche. So maybe, 40-50 machines in (if all is perfect), we break even. That point may happen 2 years into the effort.

I am not risk averse at all. Not even slightly. All I am saying is that I have just recently found some traction with my current efforts and it would take more upside potential to jump ship. If the realistic potential of the new business is that I may make $1mil over 3 years after likely working double time and weekends - I will easily stick with what I have. I am two years into my current product (contracting is almost completely a thing of the past) and the prospects are looking better than a PnP effort from scratch.

It is a fun and challenging topic that has no end. If I had no need to make money, I would actually make one just for fun. Unfortunately, I need to keep my business going for now so can only talk about the ideas. If I had $500k and wanting to start a new and profitable business - I doubt I would choose this.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #101 on: May 11, 2016, 06:32:49 am »
Quote from: rx8pilot on May 10, 2016, 10:29:47 pm
Quote from: bootstrap on May 10, 2016, 09:22:43 pm

You are increasingly convincing me that checking the position of tiny components with the down-looking "nozzle camera" before moving to pick them up... is the safe and reliable way to go.  However, note that each time it finds the component with the camera, it detects (and remembers) the error.  After a few picks of a given tiny component the software should be able to tell whether it can continue without pre-checking with the camera, or needs to check every single time.  Frankly, my money is on "check every single time anyway" for all tiny components.  At the margins (perhaps 0805) it will become clear the mechanical precision is sufficient and camera checking is a total waste of time.

The process of picking the part will move it, so using vision on the feeder will not give you what you need to place the part - at least not with the sensitive ones. Again, not all parts are vision candidates while they are in the tape. That is why each part is scanned after it is picked up and stable. The XYT correction is different each time.

You were worried about failures to pick up parts (due to lame feeders or related issues), or components that fall off the nozzle because they were never firmly attached to the nozzle.  The purpose of vision at this point is NOT to place the component precisely (or at all).  The entire purpose is to make sure the nozzle tip comes down exactly in the middle of the component, no matter how far the component is from where it should be.

In other words, I'm very much "on board" with your claim we need to pay a lot of attention to feeder issues.  The whole point of this step is to assure every component is picked up at the exact center of the component, so our machine suffers as few pick-up problems as possible.

As a very important side benefit, this also means that some of the feeder issues that could cause reliability problems or extreme expense... can now be ignored.  The components no longer need to be positioned perfectly by the feeder system.  Result: simpler, cheaper feeders.

I'm not saying feeders don't have other potential problems.  Obviously they do.  But this is a big one, and we can absolutely solve this reliably and cheaply with this vision step.  And we only need to perform this extra step on components that need this extra step (presumably just tiny components and maybe a few rare special cases).

PS:  If bringing the nozzle tip down on the exact center of the component is not sufficient to achieve reliable pick-up, you need to explain.  Yes, obviously the tip needs to press on the component with the appropriate force, the vacuum must engage at the right time (and force), and generally do everything smoothly.  But if there are other obscure reasons for unreliable pickup, you need to explain.  Because I can only guess, not having the experience with these problems that you have.

Or if you just mean we can't depend on the component not moving/rotating on the nozzle as the nozzle touches it and picks it up, then that's "no problem", because the next step is to move over the up-looking "component camera" to learn precisely where the component is.

Quote
Quote from: bootstrap on May 10, 2016, 09:34:33 pm
SCREW MODERN BUSINESS.  Be a futuristic business or die.

Oh, and most of that millions bucks profit per year is for your/our time!  Expenses?  Near zero.

I am about as unconventional and forward thinking as they come.  I have built an entire factory into a 400ft/2 garage that I call 'Factory 400'.  I produce more at my my house than I did when i had a partner that hired a dozen people and had 5000ft/2.  I am very automation centric as well as process oriented.  That is not why I would not go for a PnP business.  It's because I have at least the same or better chance of turning my current products into a $million profit.  I am already on the market and selling right now, so I have only a trickle of R&D and the business is already in motion - building.

Expenses are not zero unless you are stealing all the materials, tools, and supplies and live on nothing.  Let's say we formed a business and it took a year to develop.  The costs would be anything but trivial - prototyping a myriad of mechanics, wiring harnesses, PCB's, software, burning things up, starting over, etc.  Let's pretend it takes 4 full iterations to get a reliable enough system to release (generous estimate) and then we get to the end of the R&D year and need to do a pilot run of 15 systems - 5 of which are demos.  That is a lot of money that is needed up front.  Now, pretend we sell the first 10 units for a gross profit of $10k ea - that may cover 1/4 of our expenses if we are lucky - but there will be issues that we have to cover for free on the early adopter units and hope they are nice enough to promote the product.  I doubt that forums that cater to hobbyists will be a great sales tool for a $20k assembly tool that is only needed if you are a full fledged business of just the right size and type.  Tiny business can't afford it, larger businesses would want to outsource high volume or buy a much more capable machine. A niche within a niche. So maybe, 40-50 machines in (if all is perfect), we break even.  That point may happen 2 years into the effort.

I am not risk averse at all.  Not even slightly.  All I am saying is that I have just recently found some traction with my current efforts and it would take more upside potential to jump ship.  If the realistic potential of the new business is that I may make $1mil over 3 years after likely working double time and weekends - I will easily stick with what I have.  I am two years into my current product (contracting is almost completely a thing of the past) and the prospects are looking better than a PnP effort from scratch.

It is a fun and challenging topic that has no end. If I had no need to make money, I would actually make one just for fun.  Unfortunately, I need to keep my business going for now so can only talk about the ideas.  If I had $500k and wanting to start a new and profitable business - I doubt I would choose this.

I'm in a similar position.  Like you, there is ZERO question whatsoever that this machine is FAR from the best business opportunity that I have.  I think we both said before, something about pick-and-place machines is interesting, compelling, fascinating or appealing to us in some way.  That's it.

Oh, plus I need one!  Lucky you already has one.  I mean two.  Or more?

And I don't rule out just making a couple or three for us... assuming we come up with a design that turns us on, and we're convinced is worth the trouble.

As a business opportunity though, there are endless ways to play this... especially if we basically just decide to design and build a couple for ourselves.

From past experience (approaches I've taken before):

#1:  Find some capable engineer who is also fascinated with pick-and-place, but doesn't have all the opportunities we have, and let him run the company from his garage (once we set him up in lean, mean, cheapo-machine fashion).  We do ZERO work from then on, and he sends some percentage of gross revenue (10% to 25% perhaps).  Lots of people would LOVE to have their own business, and don't expect anywhere near the monetary rewards you and I do, but don't know how to do it.  For someone to show up in their life and drop something like this onto their lap is like a dream come true.  Yes, we can't just accept anyone who wants the opportunity, because most people are incapable and/or scam artists and will just destroy everything or stab us in the back.  But... we might be able to find someone suitable.

#2:  What almost always happens to me in the past is this.  I develop a new product.  Sometimes someone in an existing company hears about what I created from someone who has seen me testing my prototype.  They contact me and buy the product to add to their product line.  Or if that doesn't happen, once the prototype is done and working reliably, I take a rare trip out of my cave and demonstrate the product to companies that manufacture and market similar products.  For me, this has almost always generated a sale.  Then the product is totally out of my hands, I walk away with a big check in hand, and go work on my next project (which at that point is about 100,000,000,000,000 times more interesting than the "been there, done that" project I just finished).  I bet that's how your brain works to.

Now I must say, I never charged anywhere near what I should have for products, and that's part of the reason it was totally trivial to sell them.  Fact is, I would usually have a list of 3~6 companies to present to, and never did I reach the final company.  So take the above in the proper context... that would can probably get nice checks, but they won't make us rich.  Just let us retire and live a comfortable but frugal life if we wanted.  Which, actually, I can do now if I don't spend too much money to keep developing new products and technologies!  So for me, this would just create a convenient buffer.

I don't count developing expenses in my computations.  That's just not how I think.  I treat the development process (and expenses) separate from the business.  So the cost of running the business is independent in my mind.

As a matter of fact, of course whatever we would receive from the biz is both paying back our development expenses, then paying back something less than the time we spent was worth (given we are the kind of people we are).

Bottom line:

#1:  The main motivation to brainstorm this issue is... because we find it interesting.  PERIOD.

#2:  The main motivation to create physical prototypes and make them work is... because we want to.  PERIOD.

#3:  The main motivation to generate revenue in one way or other is... because "why not" (we got this far).

So I'm not going to try to convince you this is a great business opportunity FOR US, because IT SUCKS.

It flat out IS NOT a business opportunity.  It is a "side interest" for us, for lack of a better term.

We don't even need to take step #3.  However, if we develop the sucker, and it works great, and costs what we hope, then why not sell it to some company, or set someone worthy up to have the kind of business we can create almost in our sleep, but they can't.  I know you know something that I shouldn't say here, because it will just piss a bunch of people off.  But given our histories and something [perhaps undefinable] about our nature, we can do things that the vast majority can't.  So our motivations are different.  That's just the way it is.  As a business opportunity, this project is something like silly or lame.  But like you, I've had that itch (or little voice in the back of my mind) saying to me "you should build one of those... you can do better and it will be interesting and satisfying".  I think you do to.  And that's the only legit reason we should given the facts of the matter as I see them.

I feel it is way too early to get serious about business.  For the moment, this project is just to scratch an itch, work out a jigsaw puzzle, satisfy our curiosity, enjoy the process of problem solving.

PS:  I'm no multi-millionaire, or even a singular millionaire.  But I'm on the way, have no debt (never have), low expenses, and know how to live both a very comfortable and inexpensive life simultaneously.  Frankly, I'm very frugal about everything... except the quality of my development equipment and tools that let me "do my thing".  My goal is not to become rich or "captain of industry".  My goals are much simpler (follow my interests) and much more grandiose (yet practical with technology I already developed).  So much more grandiose that I shall refrain from starting any chaos here by elaborating on that here.
« Last Edit: May 11, 2016, 06:46:37 am by bootstrap »
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Offline Smallsmt

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Re: New Pick and Place design ideas
« Reply #102 on: May 11, 2016, 12:21:24 pm »
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The expensive machines that cannot place tiny components do not fail because they are moving too fast.  How do I know?  Because they could slow down for problematic/tiny components if that was all they needed to place them precisely.

Interesting but totally wrong you need much better mechanic and high precision nozzle and vision system. A belt machine can't do because need linear measurement system on x an y axis for position feedback. Next point is the vibration problem for a stepper motor system and head swinging because of using belts.
« Last Edit: May 11, 2016, 04:06:35 pm by Smallsmt »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #103 on: May 11, 2016, 06:21:17 pm »
Quote from: Smallsmt on May 11, 2016, 12:21:24 pm
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The expensive machines that cannot place tiny components do not fail because they are moving too fast.  How do I know?  Because they could slow down for problematic/tiny components if that was all they needed to place them precisely.

Interesting but totally wrong you need much better mechanic and high precision nozzle and vision system.  A belt machine can't do because need linear measurement system on x an y axis for position feedback.  Next point is the vibration problem for a stepper motor system and head swinging because of using belts.

I don't understand how your answer relates to my question.  So I'll ignore that aspect and just comment on the content of your message.

When you say "need much better mechanic", I assume you mean "much better position precision on x,y axes".  If not, please elaborate.

When you say "a high precision nozzle", I have to ask those who pick 0201 and smaller components, what does this mean?  I guess my assumption is, a nozzle with a tiny tip and hole is designed for 0201 components and thereabouts, and would therefore automatically be "high precision".  Otherwise, what would the point be of making a tiny nozzle that doesn't work reliably?  If the bottom line is that some tiny nozzles aren't high enough precision and some are, then we would obviously have to support some existing high precision nozzle (for those tiny sizes at least), or make our own.

Tell me what aspects of the nozzle must be high precision?  It seems obvious to me the tip must be precisely centered on the axis of the nozzle, and the hole be precisely in the center of the tip.  And I assume the bottom must be precisely flat, the ID and OD edges must have no burrs or irregularities, and not be sharp edges (45s).  For the tiny sizes, I'd definitely chose some kind of non-corroding hardened steel (or ceramic/glass) and make them ground instead of turned.

But better for you to tell me what you mean by "high precision" than for me to guess.

Please explain further why a belt machine won't work.  How about a belt machine with linear glass scales?

As for stepper motors, I personally abhor them for a few reasons.  I've been a major fan of DC servos + encoders for ages, though in a few special cases I have designed in steppers.  We won't be able to afford my favorite motors (DC brushed pancake motors (servos)), but plenty of other cheaper DC [servo] motors will work.

I know we have too long a topic here for everyone to read everything, but somewhere far back there is a discussion of how we can make the equivalent of glass scale linear encoders for super-cheap.  That option is still on the table.

If you could describe in MUCH greater detail the various specific failure cases and causes, I would GREATLY appreciate that.  Thanks.
« Last Edit: May 11, 2016, 07:20:19 pm by bootstrap »
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Offline Smallsmt

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Re: New Pick and Place design ideas
« Reply #104 on: May 12, 2016, 01:35:26 am »
Quote
When you say "need much better mechanic", I assume you mean "much better position precision on x,y axes".  Please explain further why a belt machine won't work.  How about a belt machine with linear glass scales?
You need linear guides and a closed loop position system which is working fast!
Servo motors combined with ball screw spindle can do the job without adding a flexible component like belt.


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When you say "a high precision nozzle", I have to ask those who pick 0201 and smaller components, what does this mean?  I guess my assumption is, a nozzle with a tiny tip and hole is designed for 0201 components and thereabouts, and would therefore automatically be "high precision".  Otherwise, what would the point be of making a tiny nozzle that doesn't work reliably?  If the bottom line is that some tiny nozzles aren't high enough precision and some are, then we would obviously have to support some existing high precision nozzle (for those tiny sizes at least), or make our own.

The rotation and the height tolerances have to be perfect to place small components. You receive the biggest problem on pickup for the placement you can use the visual system.
Expensive machines use index on A – axis to do an individual calibration for each nozzle and take care you need to restore the position if you use a nozzle changer. The Samsung nozzle we use where build using a ceramic steel combination. Maybe you receive higher precision if the nozzle has no spring element and the system use a force feedback sensor.


Quote
I know we have too long a topic here for everyone to read everything, but somewhere far back there is a discussion of how we can make the equivalent of glass scale linear encoders for super-cheap.  That option is still on the table.
But your camera solution need to be very fast!
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #105 on: May 12, 2016, 06:08:35 pm »
Quote from: Smallsmt on May 12, 2016, 01:35:26 am
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When you say "need much better mechanic", I assume you mean "much better position precision on x,y axes".  Please explain further why a belt machine won't work.  How about a belt machine with linear glass scales

You need linear guides and a closed loop position system which is working fast!  Servo motors combined with ball screw spindle can do the job without adding a flexible component like belt.

Remember the target market and our goals:  precision == YES : speed == NO.  Sure, if we find we don't have to slow the machine down too much, great.  But we are willing to accept 2x to 5x slower speed to meet the other goals.

However, I would add another "goal" here after all the conversations with rx8pilot and others.  While we willingly allow the machine to be slow as necessary (to achieve low price), we pay great attention to operator efficiency.  What does this mean in practice?

For example, in the nominal version of the machine, once the operator starts the job, he need not hang around.  He can go do something else.  Perhaps he will load other feeders and feeder banks for the next job, or something completely unrelated.  But we don't want him to hang around to help the machine.  This may not be an absolute 100% necessary goal (if it adds too much cost), but it is an extremely desirable goal that we shouldn't give up unless we absolutely cannot find a way around it without greatly increasing the price.  However, depending on the final configuration, we might have a "stripped down" model for engineers that simply cannot pay more than the price of the stripped-down model, and are willing to waste hours to help the machine along at certain steps (like maybe there is only one active feeder, which must be manually changed after those components are placed).

The consequence of all these considerations is... the machine can run slow, as long as it can do so without being attended.  The goal of the machine is VERY LOW VOLUME... for assembling 1~5 "prototypes", for assembling a run of 5~20 "demo-PCBs" for alpha and beta testers of your product... for assembling 1~20 specialty products that are part of products you sell once in a blue moon.  This is not intended to be a production machine!  For that, you spend $40K to $500K (depending on volume requirements), not the $10K to $20K we ask.


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When you say "a high precision nozzle", I have to ask those who pick 0201 and smaller components, what does this mean?  I guess my assumption is, a nozzle with a tiny tip and hole is designed for 0201 components and thereabouts, and would therefore automatically be "high precision".  Otherwise, what would the point be of making a tiny nozzle that doesn't work reliably?  If the bottom line is that some tiny nozzles aren't high enough precision and some are, then we would obviously have to support some existing high precision nozzle (for those tiny sizes at least), or make our own.

The rotation and the height tolerances have to be perfect to place small components.  You receive the biggest problem on pickup for the placement you can use the visual system.

Expensive machines use index on A – axis to do an individual calibration for each nozzle and take care you need to restore the position if you use a nozzle changer. The Samsung nozzle we use where build using a ceramic steel combination.  Maybe you receive higher precision if the nozzle has no spring element and the system use a force feedback sensor.

I forgot to mention one of my ideas about precision of nozzle-tip location after changing nozzles.  Since by definition the nozzles have a hole in the end of the tip, we can put an LED at the top of the nozzle spindle.  So after the machine (or operator) changes nozzles, it can move over the up-looking "component camera", and that camera can very precisely see the aperture on the nozzle-tip, determine the position precisely, and until the next nozzle change, apply the correction.  Since I don't know about the dozens of pick-and-place machines on the market, I have no idea whether this is a novel idea or not, but should be quite cheap, since we already have the up-looking "component camera".

About vertical position being so critical.  Are you saying the nozzle is not spring loaded along the z-axis?  Are you saying the nozzle tip must just barely touch the top of the 0201 component because it is not spring loaded?  I can see that the spring loading must be extremely low force for tiny components like 0201, otherwise risk causing the component to dislodge or shift.

One other idea I had a long time ago but forgot until now.  If the bottom of the component tape slides along on a piece of metal, the first time the machine goes to pick up a component from a new feeder, it could slowly lower the nozzle tip onto the metal.  The moment the nozzle tip touches the metal, that would complete a circuit, and the software could record the exact position of the bottom of the component tape.  If the height of the top of these components above the bottom of the component tape is known, we now know precisely how far to lower the nozzle to pick up those parts.  Frankly, if that dimension is not part of the spec for the component, we can require the operator measure this for each component and add it to his database.  That only needs to be done once per specific part.  Also, probably ALL 0201, 0402, 0603 or 0805 resistors [from any given manufacturer] are identical height, which will save a lot of time.

Actually, if we want to be extra-elaborate and convenient, we can have a lightly spring loaded metal clip of known thickness on the opposite side of the tape that can be rotated over the component on the tape and rested on top during this "component feeder sync" process.  Then the machine would perform the same action again except this time on top of the metal clip on top of the component and have an exact measure of the component thickness (after subtracting the known clip thickness).  I can think of a couple automatic ways for the machine to accomplish this without the operator moving the clip back and forth, but they don't seem quite as robust and foolproof as I'd like.  Maybe someone else can invent something more clever (or maybe I can with more time and thought).


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I know we have too long a topic here for everyone to read everything, but somewhere far back there is a discussion of how we can make the equivalent of glass scale linear encoders for super-cheap.  That option is still on the table.
But your camera solution need to be very fast!

Yes and no.  If it was necessary to continuously keep track of the position to full resolution, to implement a linear encoder with the camera would indeed require insanely if not impossibly fast camera and software.  However, if we assume the machine has cheapo rotary optical encoders on the servo motors (or gag, steppers), that should be sufficient to know where the nozzle-head is within around 0.010" == 0.250mm == 250u with even lame mechanics.

Only when the head stops somewhere important do we need know position to high precision.  And the way the current design works, the machine and algorithms are not at all concerned with the absolute position of the nozzle-head.  Why?  Because it looks at the PCB surface and makes all position decisions based upon fiducials or component pads on the PCB surface.

In other words, what matters is the ability to move the nozzle head slowly to exactly center the nozzle-camera over the component center (or alternatively know exactly what point on the PCB near the component center the nozzle-camera is currently over).  That becomes the "reference point", and the next motion is to move the nozzle-head the exact known distance between "component camera" and "nozzle tip" to center the component over the PCB.  That motion is not very far (probably 50mm to 80mm).  Even this move can be done crudely and quickly at first (based on the less precise rotary encoders), and then getting the exact position (from the camera-driven fake linear encoder) must be done very slowly anyway (compared to normal motion, though still only a fraction of a second presumably).

As I said somewhere before, the ironic fact is this.  The very first PCBs I need to make are "robotics vision system cameras" that are superb for this application (but frankly way, way, way higher performance than we need for this machine).  So if we can't find any perfect cameras, we can adopt something cheap and lower performance for the time being, then substitute our own custom cameras later, once they're available.  A lot of tiny, high-resolution and not too expensive cameras have come out recently, so we have lots to choose from (just look at quad-copters these days and pay attention to the cameras they have on them).  What is the best final choice in cameras... I have no idea yet.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #106 on: May 12, 2016, 08:54:41 pm »
Here is a terrible idea that will probably make everyone puke.  But I toss it out there anyway in case it stimulates ideas in others who know factoids or have expertise to replace or circumvent the terrible parts, or else make them work.

At the moment the assumption is this:

#1:  We have an x,y stage like most pick-and-place machines, but it must be inexpensive, so even with all our expertise, we cannot assume it will be precise enough to pick-up and place 0201 discretes and 0.30mm pitch BGAs/QFNs/etc "blind"... where "blind" means "just based upon the inexpensive rotary encoders coupled to the x,y motor shafts and without vision".

#2:  So we plan to leverage inexpensive but high resolution leverage cameras AKA "machine vision" in a few clever ways to achieve the precision we need.  Though not entirely accurate, we basically replace "precision mechanics with linear glass scale encoders on the x,y axes" with "machine vision".

#3:  To place components precisely we stop the "nozzle camera" over the center of the component as best we can based upon our inexpensive rotary encoders and modest mechanics.  Even with lame mechanics and drive system, we should be able to get within 0.010" == 0.250mm of desired positions.

#4:  Once we are [roughly] over the next component on the PCB, the down-looking "nozzle-camera" captures an image of the area of the PCB where the current component will be placed.  The image processing software finds and identifies known features within the field of view... "global fiducials", "local fiducials" component pads (if edges are free of solder paste), etc.  From that information the software precisely determines the position on the PCB that is at the exact center of the down-looking "nozzle-camera" image.

#5:  In front of the nozzle-camera lens are two flat glass windows tilted at angles to faintly reflect ghost images of the "x-rail" and "y-rail" of the pick-and-place machine.  These rails are the fixed x,y rails along which the "nozzle-head" is moved.  On these rails are tiny 0.0005" == 0.012mm aperture slits backlit by LEDs, roughly 50mm apart.  As the "nozzle-head" is moved in x and y, the images of these slits move.  Because the scale of this camera is 0.001" == 0.025mm per pixel at the focus distance (distance to PCB surface), the image processing software can distinguish slit positions to about 0.0005" == 0.012mm precision.

#6:  Once we know the "nozzle-camera" is precisely over the center of the component, we can move the "nozzle-head" any x,y distance we wish within 0.0005" == 0.012mm precision by means of the slit image positions.  Since we know the precise fixed distance between down-looking "nozzle camera" and the "nozzle head", we can now move the "nozzle-head" the exact x,y distance to bring the component center directly over the point on the PCB that the component center must be placed.

#7:  The component can now be placed.

-----

The potential problem that many previous messages discussed is... how can the software be certain it can always find "local fiducials" or "unsmeared component pads" in the field of view of every component (small or fine pitch enough to require precision placement)?  The idea of treating via pads as fiducials was kicked around, but eventually rejected.  The idea of requiring "local fiducials" was proposed and received mostly positive responses.  But the drawback of this requirement is that some existing PCBs (without "local fiducials") cannot reliably be assembled.  This is not a "killer", but is an annoying drawback.

How can this be resolved?  How can all PCBs be supported, with or without "local fiducials"?

One approach is to require solderpaste application to the PCB to be done well enough that solderpaste is not smeared beyond the edges of component pads.  In this case, the software can determine the center and rotational orientation of each component by its component pads before the component is lowered into place.

And so, this is a request for everyone who assembles PCBs to respond below with your estimate of how often this requirement would be met (only worried about tiny discretes (<= 0603) and fine-pitch components (<= 0.80mm pitch) you prepare for assembly.

Note that with more effort the software can probably work reliably if the solder paste extended beyond the edge of some component pads.  As long as the software can find at least 2 pads with clean edges on both sides of the pad in the x direction, and at least 2 pads with clean edges on both sides of the pad in the y direction, the software can infer where the component center is... with some effort.  So a few instances of solder paste hanging over the edge of pads should be tolerable (but require more software effort).

The consequence of this consideration is... the chances both pads of 2 or 3 pad discrete components are sufficiently free of smeared solder paste is much lower than components with many pads.  On the other hand, if a few other "clean" component pads (for discretes or otherwise) can be found within the field, the software can determine position from them.  This is somewhat problematic, however, because as more components are placed, more component pads are covered by components, leaving fewer for this purpose.

To be sure, a LOT of extra software work can greatly improve the reliability of this process.  For example, before component placement begins, the software could scan the PCB, find all component pads with clean sharp edges, and compute whether the default order of component placement will always result in success (sufficient position references available and uncovered for every component).  This will always be the case if application of solder paste is neat and clean (not smeared over the edges of pads), but not necessarily otherwise.  If it finds the nominal order doesn't work, it can attempt to find an order of component placement that works.  If that fails, it can BEEP and tell the operator to clean the PCB and apply solder paste again.

Of course, none of this is required when PCBs have "local fiducials" per the instructions that come with this machine.

-----

Finally we arrive at the terrible idea that may or may not be something we can find ways to make practical.

That is... solder paste is not applied to the PCB before component placement.

Instead, we make the machine apply solder paste to the pads of the component we are about to place, just before we place the component.

The process would work like this:

#1:  We follow the process as described earlier in this message.  When the time comes to find fiducials or component pads to determine where the down-looking "nozzle camera" is over, we always perform this process on the bare (solder-paste free) component pads rather than looking for "local fiducials" or component pads without smeared solder paste.

#2:  After we sync up position of the "nozzle-camera" (and thus "nozzle-head") with the PCB surface (which means, move the "nozzle-camera" precisely over the component center and consider this our <0.00000, 0.00000> reference position for this component, we move a "paste-nozzle" to each component pad lower the tip almost to the pad, then squirt out the appropriate quantity of solder paste onto the pad.  Obviously this "paste-nozzle" is also at known, fixed x,y distance from "nozzle-camera" and nozzle-tip.

#3:  Once the solder paste is applied the down-looking "nozzle camera" can move over the component center again, capture an image, and run a quality control check of the applied solder paste... and reapply to any pad that didn't receive enough paste if the software can be made that smart.

#4:  The component can then be moved to the appropriate position and placed.

This approach has some benefits and some drawbacks.

APPROACH BENEFITS

#1:  No stencil printer need be purchased (one time $$$ savings).
#2:  No stencil need be purchased (once per PCB $$$ savings).
#3:  No solder paste wasted, presumably (once per PCB $$$ savings).
#4:  No need for operator to apply solder paste to PCB (once per PCB time savings).
#5:  Reliable and precise placement of solder paste (if we do our job well).
#6:  Volume of solder paste can be variable for special pads/cases/components.
#7:  No need for any "local fiducials", so machine can reliably assemble all PCBs.
#8:  add more here ... ?????

APPROACH DRAWBACKS

#1:  Extra complexity of machine.
#2:  Extra complexity of development (could be substantial).
#3:  Higher price of machine --- must add less to price than quality stencil printer.
#4:  add more here ...  ?????

-----

Well, that's my terrible idea.

If someone here just finished 5 years of experiments to get to the point he can reliably apply solder paste with some not-to-expensive nozzle or gizmo he developed... well... maybe this idea looks a bit less terrible.

Otherwise, this whole "apply solder paste" activity could be a huge bag of worms!  I'm pretty good with mechanics, optics, electronics, software and lots of other things, but I have very little experience "squirting" or applying pastes to anything.  Or even liquids for that matter.  So... I'd be starting from ground zero.  I read some forum messages in the past 3 or 4 years from people playing with solder paste application with nozzles and such, but they were mostly tales of woe.  Haven't read much in a year or more though, so maybe someone has made progress.  Or maybe there is even an inexpensive product on the market to eject solder paste that we could integrate into the machine.  A lot can happen in a year or two in this industry, but... Murphy's Law probably applies to our wish there is such an inexpensive device available that we can just adopt.  If anyone knows better, please yell loudly and soon!

-----

As always, comments welcome, and ideas, suggestions and brainstorming especially welcome.  No need for excessive negativity, since that's already presumed in advance on this idea!

Oh, and everyone with first-hand experience assembling PCBs, do answer that question above... about what percentage of component pads with solder paste applied still have clean edges.
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #107 on: May 12, 2016, 09:29:02 pm »
Solder paste dispensing  and 0201's - never gonna work.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #108 on: May 12, 2016, 09:38:21 pm »
Quote from: mikeselectricstuff on May 12, 2016, 09:29:02 pm
Solder paste dispensing  and 0201's - never gonna work.

Just because, huh?

You can explain the reasons you believe that?  Proprietary information?
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #109 on: May 12, 2016, 09:58:49 pm »
Dispensing systems are notoriously hard to get to work reliably, even for larger geometries. Issues like surface  tension, adhesion, viscosity dependence on temperature, paste uniformity all affect the result.
The size of nozzle you'd need for fine pitch QFPs would be too small to get any reasonable flow rate due to the metal particles in the paste.
If it was viable for fine pitch, Mydata wouldn't have any market for their very expensive paste-jet printers.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #110 on: May 12, 2016, 10:02:13 pm »
Quote from: mikeselectricstuff on May 12, 2016, 09:58:49 pm
Dispensing systems are notoriously hard to get to work reliably, even for larger geometries.  Issues like surface  tension, adhesion, viscosity dependence on temperature, paste uniformity all affect the result.  The size of nozzle you'd need for fine pitch QFPs would be too small to get any reasonable flow rate due to the metal particles in the paste.  If it was viable for fine pitch, Mydata wouldn't have any market for their very expensive paste-jet printers.



I guess 0.20mm is too big but a little?  But this seems to be just "some guy" doing this six years ago.

-----

I know it's easier to talk than do, but maybe it is possible to flash-heat just enough solder paste just inside the end of an appropriate size needle to vaporize the flux and eject it out and onto the PCB (carrying the metal in it).  I guess that's heading in the direction of the MyData, but that machine is extremely fast, probably has oodles of heads, and is actually shooting out dots of solder paste before it gets to the pad, and computing how far it will travel in order to hit the pad.  That's so far beyond what I'm talking about in sophistication, it is dangerous to pretend they are the same.

Found the link here:  https://forums.adafruit.com/viewtopic.php?f=42&t=16273

Not sure, but maybe that would work for 0.50mm pitch but not 0.30mm - however that's just a guess.

Oh, I see you posted on that page!  How did that research go?  Very bad, I have to assume!
« Last Edit: May 12, 2016, 10:11:28 pm by bootstrap »
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #111 on: May 12, 2016, 10:09:22 pm »
Once you see the price and consider the process complications - you might realize that stencils are the best option. If you were making huge numbers of very time sensitive one-off, it may make sense. Stencils are very cheap and very reliable. Very few practical use cases for fine pitch solder jet dispensing IMHO.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #112 on: May 12, 2016, 10:12:50 pm »
Quote from: rx8pilot on May 12, 2016, 10:09:22 pm
Once you see the price and consider the process complications - you might realize that stencils are the best option. If you were making huge numbers of very time sensitive one-off, it may make sense. Stencils are very cheap and very reliable. Very few practical use cases for fine pitch solder jet dispensing IMHO.

Can you answer the question in my long post?  What's the statistics on how many pads have "clean edges" (not overflowed by solder paste)?

BTW, you say "stencils are very reliable", but so many people I talked to who actually have pick-and-place machines and actually assemble PCBs say... most of their bad boards are from bad application of solder paste with stencils.  And they say that is the biggest hassle of the whole process too.

I'm not contradicting anyone here.  I just don't give up to fast and easy!

PS:  Anyone know whether solder paste can be heated up some (for a few seconds) to make it less viscous without having the flux and solder balls separate?  Then maybe application isn't such a hassle.

Found two "close but no cigar" units:  fisnar: PDV-1000 and RV5000DP
http://www.fisnar.com/products/positive-displacement-valves/pdv1000-2

Unfortunately, smallest dot size is 0.020" == 0.50mm (2~3x too big for 0201 or 0.50mm pitch).
« Last Edit: May 12, 2016, 10:52:41 pm by bootstrap »
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Re: New Pick and Place design ideas
« Reply #113 on: May 12, 2016, 11:42:30 pm »
Quote from: bootstrap on May 12, 2016, 10:12:50 pm
BTW, you say "stencils are very reliable", but so many people I talked to who actually have pick-and-place machines and actually assemble PCBs say... most of their bad boards are from bad application of solder paste with stencils.  And they say that is the biggest hassle of the whole process too.

My first efforts with stencils did not go well. So I did some reading and experiments and discovered that printing solder paste is not a freebie. The design of the stencil is critical. The quality of the apertures. Then you have the technique mixed with the actual paste chosen. It takes a few bad prints to get it right, but when you do - it is very easy and very fast and very cheap. Just do not underestimate the learning curve if you are doing fine pitch printing. There is very little room for error but like riding a bike - it seems nearly impossible at first and then you get it for life.

I have no doubt that jet printing will work just fine, but the economics don't seem to add up. There is no practical benefit to doing a jet print/place - jet print/place scheme that I can think of. Print it, place it, bake it. What is faster or more economical? If economy is not the goal, jet printing and a really nice in-house PCB fab could save a bit of time, but at a wildly huge cost. The reality today is that PCB's and stencils are super cheap and fast. So much so, that the viable market for stencilless printing is pretty small. Maybe an assembly house that specializes in prototype assembly? Not sure.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #114 on: May 12, 2016, 11:52:40 pm »
Quote from: rx8pilot on May 12, 2016, 11:42:30 pm
Quote from: bootstrap on May 12, 2016, 10:12:50 pm
BTW, you say "stencils are very reliable", but so many people I talked to who actually have pick-and-place machines and actually assemble PCBs say... most of their bad boards are from bad application of solder paste with stencils.  And they say that is the biggest hassle of the whole process too.

My first efforts with stencils did not go well.  So I did some reading and experiments and discovered that printing solder paste is not a freebie. The design of the stencil is critical. The quality of the apertures. Then you have the technique mixed with the actual paste chosen. It takes a few bad prints to get it right, but when you do - it is very easy and very fast and very cheap. Just do not underestimate the learning curve if you are doing fine pitch printing. There is very little room for error but like riding a bike - it seems nearly impossible at first and then you get it for life.

I have no doubt that jet printing will work just fine, but the economics don't seem to add up. There is no practical benefit to doing a jet print/place - jet print/place scheme that I can think of. Print it, place it, bake it. What is faster or more economical? If economy is not the goal, jet printing and a really nice in-house PCB fab could save a bit of time, but at a wildly huge cost. The reality today is that PCB's and stencils are super cheap and fast. So much so, that the viable market for stencilless printing is pretty small. Maybe an assembly house that specializes in prototype assembly? Not sure.

Yeah, this idea is a long shot.  But, I consider long shots until I realize they won't work or are impractical.    |O

Also, the bottom line is that all this hassle only solves one "shortcoming" of the proposed design... the need for "local fiducials" (or take your chances the PCB design doesn't have enough reference marks of other kinds for the software to determine position precisely).  Seems like nobody thought requiring "local fiducials" was a killer requirement, and I tend to agree with that.  So yeah, this probably is a wild goose chase.

Looks like Norton has a DV-01 syringe valve that can lay down dots of fine solder paste, but unfortunately no smaller than 0.20mm.  That is just a tad too big for 0201 and maybe adequate for 0.50mm pitch, but nothing smaller (and 0.30mm is my "if possible" goal).

My guess is, someone will release a cheap version of the spider or scorpion machine in 5 years.  Or if it comes from China, maybe 2 or 3 years?
« Last Edit: May 13, 2016, 12:12:41 am by bootstrap »
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Online forrestc

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Re: New Pick and Place design ideas
« Reply #115 on: May 13, 2016, 02:14:19 am »
In relation to dispensing solder paste:

Figuring out how to do this reliably and consistently and inexpensively would be FAR more marketable than any P&P you could come up with.

I have a high end paste dispenser on my P&P (time and pressure).   I use it for the first run prototypes and for production of lower volume products.  Generally, every product I have has had the first hundred or so manufactured using it.  (If you're curious, the brand I have is Martin.  I have one version prior to the current products).

It's fine for larger pitch components.  Once you get down to 0.5mm TQFP's and similar, you're entering into the realm of it doesn't really work all that well (although it's good enough if you're ok with occasional/frequent rework).  It definitely wouldn't come anywhere close to six sigma at 0.5mm.


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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #116 on: May 13, 2016, 02:54:51 am »
Quote from: forrestc on May 13, 2016, 02:14:19 am
In relation to dispensing solder paste:

Figuring out how to do this reliably and consistently and inexpensively would be FAR more marketable than any P&P you could come up with.

I have a high end paste dispenser on my P&P (time and pressure).   I use it for the first run prototypes and for production of lower volume products.  Generally, every product I have has had the first hundred or so manufactured using it.  (If you're curious, the brand I have is Martin.  I have one version prior to the current products).

It's fine for larger pitch components.  Once you get down to 0.5mm TQFP's and similar, you're entering into the realm of it doesn't really work all that well (although it's good enough if you're ok with occasional/frequent rework).  It definitely wouldn't come anywhere close to six sigma at 0.5mm.

Is this the unit you mean?

http://www.martin-smt.de/en/dispensing/products/dotliner.html

Amazingly, they claim the dot can be as small as 0.10mm, which should be adequate for 0.50mm pitch, 0.40 pitch, and maybe even 0.30mm pitch if true.  The only negative is, they don't seem to sell just the valve.

Unless... ???  Maybe this is a nozzle: <HT00.8008>  ?????
« Last Edit: May 13, 2016, 03:00:02 am by bootstrap »
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Offline C

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Re: New Pick and Place design ideas
« Reply #117 on: May 13, 2016, 04:56:32 am »
I am reading optic camera, but not seeing some uses it could help with.

PCB set on a conveyor belt would let the system be more useful.

One problem is where the PCB is and it's rotation.  Optics handles this but a Pin that could be lowered to catch the PCB board edge would let the board be rotated on the belt for better placement of parts.

By using the camera more you could then feed a blank PCB with out paste and shift to a different PCB by scanning the blank and comparing stored images of boards. This could also check that the place commands matches the PCB.
A new blank PCB could then start the process of creating the parts place files if one did not exist.

A scan of a PCB with paste before placing parts could check for proper paste.
A scan of a PCB after placing parts could check for proper placement.
An image of the PCB could get enough copper detail through the solder mask to allow placing of parts.
 
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #118 on: May 13, 2016, 07:02:12 am »
Quote from: bootstrap on May 13, 2016, 02:54:51 am

Amazingly, they claim the dot can be as small as 0.10mm, which should be adequate for 0.50mm pitch, 0.40 pitch, and maybe even 0.30mm pitch if true.
"can be as small as 0.1mm" doesn't mean " will reliably produce 0.1mmm dots every time".
Manufacturers will always quote the best possible performance in the ideal circumstances, acheiving it in practice is another matter.
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #119 on: May 13, 2016, 05:21:27 pm »
Quote from: mikeselectricstuff on May 13, 2016, 07:02:12 am
Manufacturers will always quote the best possible performance in the ideal circumstances, acheiving it in practice is another matter.

Like the placement rate of a P&P system.
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #120 on: May 13, 2016, 05:52:11 pm »
Quote from: C on May 13, 2016, 04:56:32 am
I am reading optic camera, but not seeing some uses it could help with.

PCB set on a conveyor belt would let the system be more useful.

One problem is where the PCB is and it's rotation.  Optics handles this but a Pin that could be lowered to catch the PCB board edge would let the board be rotated on the belt for better placement of parts.

By using the camera more you could then feed a blank PCB with out paste and shift to a different PCB by scanning the blank and comparing stored images of boards. This could also check that the place commands matches the PCB.
A new blank PCB could then start the process of creating the parts place files if one did not exist.

A scan of a PCB with paste before placing parts could check for proper paste.
A scan of a PCB after placing parts could check for proper placement.
An image of the PCB could get enough copper detail through the solder mask to allow placing of parts.

We can't have a conveyor belt, because we need to support PCBs with components in both sides.  But we can support rails like in the neoden4.  They are quite "cool" as far as I'm concerned, and I can see conveniences (like being able to queue up several PCBs, then leave and let the machine assemble them all).  Depending on cost, this could be standard or option.

I don't see how rotating the PCB on the belt is very helpful.  It is convenient for PCB surface axes to align with machine axes (via <fiducial inspection, tweak, loop> iteration), but that's not necessary (position and coordinate adjustment is typically done in software and works fine).

The only version of "rotate the PCB" that I consider useful is... if the PCB can be rotated 360-degrees (like on a rotary table).  In that case, rotating the PCB can replace rotating the nozzle (or they can complement each other).  On a machine where x,y motion was implement by moving the PCB, putting rotation under the PCB can work, but is more expensive and more complex software than nozzle rotation.

Yes, we have a lot of messages in this topic, and those camera ideas you mention are part of the current design plan mentioned previously.  As much as possible has been pushed off onto the camera and vision software in order to be able to create an inexpensive machine that can pick-up and place tiny and fine-pitch components very precisely.

For various processes, it is good to have one image of one bare "reference" PCB, an image of each PCB with solder paste applied, and image of the assembled PCB.  As you note, much information can be gleaned by intelligent software, and many errors in solder paste application and assembly can be found by automatic software.  Plus, those images can be inspected by human eyes for double checks when desired.
« Last Edit: May 13, 2016, 06:10:13 pm by bootstrap »
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #121 on: May 13, 2016, 07:08:49 pm »
Quote from: bootstrap on May 13, 2016, 05:52:11 pm

We can't have a conveyor belt, because we need to support PCBs with components in both sides.  But we can support rails like in the neoden4.  They are quite "cool" as far as I'm concerned, and I can see conveniences (like being able to queue up several PCBs, then leave and let the machine assemble them all).

And assemble longer boards than the placement area
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #122 on: May 14, 2016, 02:55:13 am »
I have a PCB conveyor and nearly all of my boards are double sided. I love it and would be bummed if the machine did not have it.
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Online forrestc

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Re: New Pick and Place design ideas
« Reply #123 on: May 14, 2016, 05:39:10 am »
Quote from: bootstrap on May 13, 2016, 02:54:51 am
[Is this the unit you mean?

http://www.martin-smt.de/en/dispensing/products/dotliner.html


No, I have a clever dispense 05.

The main problems with this include:  The variabilty of the paste at different temperatures (partially solved with the heated nozzle).  The variability of the paste as it is worked via air (each squirt of air bangs on the tube of paste, causing rheology effects).  Paste nozzle clogging and/or accumulation of paste crud on the nozzle.  And board-to-board variations (pad thickness, board flatness, etc).

On a typical 0.5mm TQFP we get 1-2 bridges when dispensing, more if things aren't quite adjusted well.   Typically zero with stencil printing.   A worse defect are dots being skipped altogether (or mostly skipped), as those are hard to find and/or fail in the field.

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Offline ServoKit

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Re: New Pick and Place design ideas
« Reply #124 on: May 14, 2016, 11:17:32 am »
Working on a dispenser myself, I've been reading up on the topic and also stumbled upon the Martin devices. Dave made a video about them some years ago:



In the comment thread someone mentions that they are in the $30K range... I thought about using an auger for controlling the flow (see attached for a first attempt)

Regards, Axel
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #125 on: May 14, 2016, 11:44:11 am »
Unbelievable what a large and expensive setup that Martin is, just for dispensing paste and it still has an alignment error  :( .
It is pretty slow compared to a decent P&P machine, so you must also have multiple of these machines to keep up with real production.
I guess these are only used for prototyping but then a decent pcb manufacturer can also deliver a stencil for a few tenners.
I think the the target audience for these machines is only dispensing red thermal glue for two sided boards?
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Offline ServoKit

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Re: New Pick and Place design ideas
« Reply #126 on: May 14, 2016, 12:31:34 pm »
I think one application for a device like this is rework, where stencils are usually not an option. But you are right, it is fairly slow and looking at the whole setup (standard aluminum extrusions, simple steppers with belt drive, apparently no encoders), that's $1500-2000 for the hardware, tops. Obviously, there's considerable know how in stuff like temperature compensation for the paste etc. - but still.

Regards, Axel
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Re: New Pick and Place design ideas
« Reply #127 on: May 15, 2016, 09:32:48 am »
Quote from: Kjelt on May 14, 2016, 11:44:11 am
Unbelievable what a large and expensive setup that Martin is, just for dispensing paste and it still has an alignment error  :( .
It is pretty slow compared to a decent P&P machine, so you must also have multiple of these machines to keep up with real production.
I guess these are only used for prototyping but then a decent pcb manufacturer can also deliver a stencil for a few tenners.
I think the the target audience for these machines is only dispensing red thermal glue for two sided boards?

I have live, shipping products for which a typical 'restocking' production run is 2 copies of a board.  By the time you put the stencil on the printer, get the paste on the stencil, print the two boards, clean the stencil and so on, you could have the boards run with the dispenser.     

In my environment the dispenser is actually on the pick and place machine as an option, so you load the board and the P&P machine does the dispensing.  We have it pause between the dispense and placement step to verify a good dispense.  Then it proceeds to placement.   There is no special setup here - you load the program for the board and it does the work.  Yes it's slow, so we don't use it for higher-volume products, but for those we do a few (<10) a month of, it's perfect.

I really like this functionality because I also do first run prototypes on the exact machine which is used for production.  Because our standard component set is on the machine we don't have to load any feeders, etc., and any specialty parts can be quickly hand-dropped on the pasted board.



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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #128 on: May 15, 2016, 03:04:05 pm »
Quote from: forrestc on May 15, 2016, 09:32:48 am
I have live, shipping products for which a typical 'restocking' production run is 2 copies of a board.  By the time you put the stencil on the printer, get the paste on the stencil, print the two boards, clean the stencil and so on, you could have the boards run with the dispenser.     

In my environment the dispenser is actually on the pick and place machine as an option, so you load the board and the P&P machine does the dispensing.  We have it pause between the dispense and placement step to verify a good dispense.  Then it proceeds to placement.   There is no special setup here - you load the program for the board and it does the work.  Yes it's slow, so we don't use it for higher-volume products, but for those we do a few (<10) a month of, it's perfect.

I really like this functionality because I also do first run prototypes on the exact machine which is used for production.  Because our standard component set is on the machine we don't have to load any feeders, etc., and any specialty parts can be quickly hand-dropped on the pasted board.
Ok you are the person with the experience , I would bet it takes time to put on a new nozzle, fill it through with paste change halfway for a smaller nozzle and afterwards clean all used nozzles also?
Or are you doing all the pads with the same nozzle, then you probably only have a very limited set of pad sizes in your design? I mean if you have to fill a 0603 pad with a nozzle capable of delivering a 0,1 drop it will take some time. But I can see it can be of value if you have a lot of different pcb's and very small series you do not have to switch stencils. Still what is the price of such machine? (oh Dave told us in the video if you have to ask you can't afford it  :) )
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #129 on: May 15, 2016, 08:54:51 pm »
Quote from: ServoKit on May 14, 2016, 11:17:32 am
Working on a dispenser myself, I've been reading up on the topic and also stumbled upon the Martin devices. Dave made a video about them some years ago:



In the comment thread someone mentions that they are in the $30K range... I thought about using an auger for controlling the flow (see attached for a first attempt)

Regards, Axel

Thanks very much for that video!  I realize those are 0402 components and it appears like the BGA is 0.10mm pitch, but the implication is the device might indeed be able to apply solder paste for 0201 and 0.50mm pitch components (especially if that's not the smallest nozzle).

I don't doubt the machine costs $30K, since it is about 80% of a complete pick-and-place machine.  However, the idea of this project is to perhaps integrate solder paste application into the pick and place machine, so all we'd need is the nozzle.

I see Martin also sells the nozzle separately, and apparently I already posted the part number of the nozzle in a previous message.  They claim the dot size can be as small as 0.150mm, which I consider adequately small for 0201 (barely) and BGQ/QFN/etc pitches down to 0.50mm and possibly 0.40mm.  I am a bit surprised they claim they can support one size smaller than 0201, but... maybe.

Another question.  The video makes it appear like the tip of the nozzle actually pushes against the PCB, then emits the solder paste as the tip rises off the PCB.  Is this true, or is that an illusion.  If the tip really does push that firmly on the PCB, I am a bit surprised, and a bit worried about damage to the tip over hundreds of thousands of applications.

Another question.  Is the quantity of solder paste applied a variable?  If so, then larger pads can be accommodated by setting a higher volume of paste to be applied with the tiny nozzle.  Also, is there a way to tell the machine to apply multiple dots to rectangular pads.  That too is a way to accommodate larger pads without nozzle changes.
« Last Edit: May 15, 2016, 09:12:29 pm by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #130 on: May 15, 2016, 09:00:11 pm »
Quote from: Kjelt on May 14, 2016, 11:44:11 am
Unbelievable what a large and expensive setup that Martin is, just for dispensing paste and it still has an alignment error  :( .
It is pretty slow compared to a decent P&P machine, so you must also have multiple of these machines to keep up with real production.
I guess these are only used for prototyping but then a decent pcb manufacturer can also deliver a stencil for a few tenners.
I think the the target audience for these machines is only dispensing red thermal glue for two sided boards?

If you noticed, the alignment error was extremely constant on every pad.  AND, very importantly, he did not let the device choose the fiducials, he manually centered on two large pads.  That's probably where the error came from, and thus the machine is likely not the error source.  Let the vision system determine position, and do so on fiducials.

I'm definitely not sold on applying solder paste with the pick-and-place machine, but I want to be totally fair as we consider all options.  Plus, IF the pick-and-place machine applies solder paste, then the true cost must be judged on the basis of being both a precise automatic solder paste stencil printer and a pick-and-place machine.
« Last Edit: May 15, 2016, 09:04:54 pm by bootstrap »
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #131 on: May 15, 2016, 09:16:33 pm »
Quote from: rx8pilot on May 14, 2016, 02:55:13 am
I have a PCB conveyor and nearly all of my boards are double sided. I love it and would be bummed if the machine did not have it.

Explain what you mean by a conveyor belt?  I was thinking that means a wide flat belt surface that moves horizontally.

Do you consider the rails on the neoden4 constitute a "conveyor belt"?  If not, are those rails an acceptable alternative?  If not, why not?
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Offline bootstrapTopic starter

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Re: New Pick and Place design ideas
« Reply #132 on: May 15, 2016, 09:23:33 pm »
Topic:  Mechanical structure and configuration.

So far this topic has mostly discussed approaches and specific details of the proposed pick and place machine.  Now I'd like to begin the discussion of various ways to implement the basic mechanics.

Rather than bias this, I'll open the floor for ideas.

PS:  The video of the Martin solder paste application system did make me wonder whether something nearly as lightweight and compact as that might suffice (not counting feeder system, of course).  Opinions?

PS:  Note that Spikee started discussing along these lines in reply #43 on page 2 of this topic, but... most of us weren't ready for that part of the discussion yet.
« Last Edit: May 15, 2016, 09:26:49 pm by bootstrap »
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Re: New Pick and Place design ideas
« Reply #133 on: May 16, 2016, 04:11:03 am »
Quote from: Kjelt on May 15, 2016, 03:04:05 pm
Ok you are the person with the experience , I would bet it takes time to put on a new nozzle, fill it through with paste change halfway for a smaller nozzle and afterwards clean all used nozzles also?
Or are you doing all the pads with the same nozzle, then you probably only have a very limited set of pad sizes in your design? I mean if you have to fill a 0603 pad with a nozzle capable of delivering a 0,1 drop it will take some time. But I can see it can be of value if you have a lot of different pcb's and very small series you do not have to switch stencils. Still what is the price of such machine? (oh Dave told us in the video if you have to ask you can't afford it  :) )

We use 24Ga disposable deedles.  Same nozzle size for all dispensing, which does limit your your dynamic range somewhat.   We could probably get more repeatable on very small parts if we didn't have to also dispense larger ones.   Just to give you an idea of the dynamic range we DO do, is that we dispense all the way from 0.5mm TQFP's to TO263AB packages with the same needle.  The TO263 heatsinks have multiple, large, dots.

The entire setup time is less than 5 minutes.   The most consuming part is actually the z axis alignment.   In addition, the syringe just stays on the machine, so if I walk out there to do a prototype, it takes much less time - say 30 seconds to uncap the needle and manually trigger the machine to squirt paste through the needle to clear any old/verify lack of clog.

Remember, that we balance our line so that for those items which are dispensing, the operators are not waiting on the machine.  Instead they're completing their inspection and additional assembly/test steps from previous boards.

As to cost, I think it added somewhere between $5 and 10K to the machine.     I looked back but I don't have an itemized quote, and I can't find the emails discussing it.
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Offline MicroBlocks

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Re: New Pick and Place design ideas
« Reply #134 on: May 16, 2016, 04:36:58 am »
This guy is getting close:

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Offline ar__systems

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Re: New Pick and Place design ideas
« Reply #135 on: May 18, 2016, 01:27:41 am »
Wow so many posts.... there is no way I'll be read all of these, so I guess I'll just reply to the first one.

I think it is a strange target machine - slow, but with 0201 capability, and 1u accuracy? Why do you need 1u accuracy? Also, if we have to place 0201, I presume it would be complex high density circuit boards with let's say 500 components on them? Dropping speed to 500cph makes our throughput at 1 pcb per hour? Pointless, imho.

Using cameras as a replacement for positioning is not going to work very well. Did you ever try filming a moving target? Possible, but definitely not with a cheap camera.
« Last Edit: May 18, 2016, 03:19:53 am by ar__systems »
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Offline MicroBlocks

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Re: New Pick and Place design ideas
« Reply #136 on: May 18, 2016, 03:54:33 am »
Better start reading the rest. First post is just that. Initial ideas that needs to be discussed and improved upon.
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Re: New Pick and Place design ideas
« Reply #137 on: May 18, 2016, 05:07:29 am »
Quote from: ar__systems on May 18, 2016, 01:27:41 am
Wow so many posts.... there is no way I'll be read all of these, so I guess I'll just reply to the first one.

I think it is a strange target machine - slow, but with 0201 capability, and 1u accuracy? Why do you need 1u accuracy? Also, if we have to place 0201, I presume it would be complex high density circuit boards with let's say 500 components on them? Dropping speed to 500cph makes our throughput at 1 pcb per hour? Pointless, imho.

Using cameras as a replacement for positioning is not going to work very well. Did you ever try filming a moving target? Possible, but definitely not with a cheap camera.

To me:

500CPH = Slow death
1000CPH = Periodic prototype
1500CPH = Slow production
2500CPH = Passable for low qty of high value PCB production

My Quad 4000C is a 3600CPH rated machine, but in reality it achieves around half of that. If I optimize the feeders and programming - it would likely struggle to see 3000CPH. I only optimize for ease of use - not speed and deal with the hit in efficiency. Also, I run the machine fairly slow which reduces some issues. This gets me around 1500-1800CPH and that is generally faster than all the other processes like printing, inspecting, re-flow, etc. For my small operation where I make a low volume of high-value PCB's - it works out ok. Would I like it to be faster? Absolutely - but the P&P machine is not the slowest part of the process so I would focus on the ancillary steps first until I was waiting on the machine. After that, I would tweak the setup to run at 100% speed. After that I would optimize the feeders.

500CPH - too slow to be interesting. 1500CPH (real CPH, not 'RATED') at $10k-15k that can do 0201 would be very interesting.
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #138 on: May 18, 2016, 11:20:18 am »
Has bootstrap lost interest.  No posts for two days
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Offline ar__systems

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Re: New Pick and Place design ideas
« Reply #139 on: May 18, 2016, 06:08:47 pm »
Quote from: rx8pilot on May 18, 2016, 05:07:29 am
Absolutely - but the P&P machine is not the slowest part of the process so I would focus on the ancillary steps first until I was waiting on the machine. After that, I would tweak the setup to run at 100% speed. After that I would optimize the feeders.

Makes sense, but only if your process is fully pipelined. If you do all by yourself, then it is not fully pipelined and every stage becomes a bottle-neck.
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Re: New Pick and Place design ideas
« Reply #140 on: May 18, 2016, 06:44:05 pm »
In general, it's a 'production line' no matter what. It cannot go into the P&P until it is printed. It can't go into the oven until it's placed. I can't do the 2nd side until the first side is out of the oven.

My process is FAR from optimal - no doubt. Even if I have more people, the machine would not be the first bottleneck even at 1800CPH (slow).
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #141 on: May 19, 2016, 04:41:35 am »
Quote from: rx8pilot on May 18, 2016, 06:44:05 pm
In general, it's a 'production line' no matter what. It cannot go into the P&P until it is printed. It can't go into the oven until it's placed. I can't do the 2nd side until the first side is out of the oven.

My process is FAR from optimal - no doubt. Even if I have more people, the machine would not be the first bottleneck even at 1800CPH (slow).

but most importnatly, its working and doing a job.
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Re: New Pick and Place design ideas
« Reply #142 on: May 19, 2016, 05:46:26 am »
Quote from: mrpackethead on May 19, 2016, 04:41:35 am

but most importnatly, its working and doing a job.


Yes! And I am thankful for that.
It's how my family eats.
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Offline Corporate666

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Re: New Pick and Place design ideas
« Reply #143 on: May 20, 2016, 07:50:03 am »
Some thoughts, since I can't help myself :)

I have 3 Quad 4C's - same machine as RX8, but different software (same mechanicals for the most part).  Before these I had a Fuji IP-3.  Before that I had two Dynapert chip shooters.  Before that I had another gantry machine.  Before that I had some customized home-brew setups.

In my humble opinion...

1) I could not agree more with RX8 when he pointed out the folly of spending a lot of time trying to overcome shitty mechanicals with all sorts of software and/or vision tweaks.  A quick and precise underlying X/Y/Z mechanical system using the right parts is not expensive or difficult to build using established and accurate parts.  There's no reason to be dicking around with substantial backlash and such.  You can and should use the software to zero-in the accuracy, but starting with linear rails, closed loop positioning and a rigid structure is a no-brainer.

2) Mike said it earlier and he's right on the money.  Feeders.  Feeders.  Feeders.  Everyone ignores feeders and focuses on placement.  Forget placement - it's easy.  Feeding and picking is the issue.  There is no point whatsoever in ignoring the feeder issue and loading little cut strips of tape on the bed of a machine and/or pre-staging parts by hand.  You spend an hour setting up the machine so you can not spend an hour placing a board.  False economy.   

3) RX8 said it right when he said that the machine he would build today, after owning a "real" PnP is not the machine he would build before he actually owned one.  That hits the nail on the head.  Most of the issues people dote over when designing in their head are non issues and they gloss over the ones that DO matter (feeders!).  A useful machine should hold a lot of parts.  It should be easy to program.  I don't care about speed all that much compared to how much I care about reliability and unattended operation.  My machines now let me go so something else.  They are not fast by modern standards, but I can place hundreds of boards per day.  And even if I am making $10 per board in profit, that would be thousands per day, tens of thousands in profit per week.  If I needed 5 times the throughput, I could buy more of these same machines, or invest in a $300k Juki/Assembleon/MyData/Universal/whatever.

4) Forget paste dispensing, IMO.  I chased that pipe dream for a while - then I re-learned a lesson I already knew.  Things are done the way they are not because everyone doing it is too stupid to think of a better way, but because the way it's done works and works well.  Etched steel stencils without frames and pasted on a desk using masking tape to hold boards in place can support multi-million per-year operations.  We can paste 500 boards (50 panels, 10 PCB/panel) in maybe 20 minutes. And we can place them in maybe 2 hours.  And reflow in about 30 minutes.  There is zero economy to be gained with paste dispensing.  The only exception is prototype boards or glue dispensing for wave soldering, but those are specialized applications.  And even then, given the time to program the machine, I've never had a case where it wasn't faster to just do it with the desktop pedal-operated dispenser.

Vision is what it is - been discussed to death and I think it's well understood and well implemented in most machines.  The big discussion should be about feeders.

I've seen all kinds on the machines I have owned - varying levels of complexity and success.  I like the Quad feeders the most.  They are self contained - basically just power and index input.  The feeder handles holding the reel, indexing a given amount, peeling the plastic cover tape, presenting the part, and adjustable index amounts.  There will always be some gears or belts involved, but a simple servo indexing the tape with a mechanical linkage tying the cover tape capture to the tape indexing I think is the best solution.

But the big elephant in the room about these projects is that you can't sell a PnP that cost $5k in parts for $10k.  You need to sell it for more like $40k.  Because when you add in the cost of R&D that you have to spread over the sales, and you factor in the marketing and sales cost, and the cost of support and warranty, you will need every bit of that margin to run a business.

If you think you will open source stuff or have online forums for support - you are limiting your customer base to hobbyists who won't spend too much on the machine, but without a real business and support, you will never get business customers interested.

PPM (the company who took over the Quad line) is not very far from my shop.  I've been up there and toured the facility.  They charge prices for spare parts, support and whole machines that most people on this thread would consider outrageous.   They are doing OK by New Hampshire small business standards, but their offices aren't exactly luxurious buildings of glass and steel.  And they get most of their machines for FREE or next to free - and if it's beat to shit or missing parts, they probably don't even want it for free.  Then they refurb them and sell them for $25-50k. 

Those are the kind of realistic margins you need to be able to sell PnP machines to business customers.  And if you sell to hobbyists, it's a very limited market (in size and how much $$ they have to spend) and IMO, probably a support nightmare.
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #144 on: May 20, 2016, 10:47:01 am »
Quote from: Corporate666 on May 20, 2016, 07:50:03 am
But the big elephant in the room

I think the big elephant has gone quiet.
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #145 on: May 20, 2016, 10:50:37 am »
On the feeder topic, im heading down a path of using Yamaha CL stuff.

The CL clone feeders cost around $50 for a 8mm, though to several hundred for bigger ones.

40 way plate ¥1999 ( USD 324.00 ) https://world.taobao.com/item/45596890497.htm?fromSite=main&spm=a312a.7700824.w4002-5269705.14.5HqNtz
20 way solenoids on Manifold ¥999 ( ~USD$164 ) https://world.taobao.com/item/522807850694.htm?fromSite=main&spm=a312a.7700824.w4002-5269705.22.5HqNtz

for $652 I will get 40 solenoids and feeder plates..    Add 40 feeders for another $2000.     Heck i might even double that and spend $5k on an 80 feeder setup.. And another $3-5k for drives, cameras, and put Open pnp on it, and i'll ahve spent about $10k + time, but learned a lot, and i susspect i'l have a machien that runs as well as our Yamahas... 

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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #146 on: May 24, 2016, 12:15:03 am »
Can i assume this project now is dead?
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #147 on: May 24, 2016, 03:24:25 am »
Quote from: mrpackethead on May 24, 2016, 12:15:03 am
Can i assume this project now is dead?

I don't think it was ever a project - more of a random grouping of thoughts about how to put parts on a circuit board. Interesting discussion to participate in though, especially since I have so recently learned the daunting task of PCB assembly by P&P machine. The nuances are plentiful and hard to anticipate until you have done it.

My machine is reliable, rigid, accurate, repeatable, flexible and a host of other good things - but PCB assembly is still a remarkably pain in the ass endeavor. The whole system and process has to be 100%. 99% accurate creates enough work that you may as well assemble by hand. Super unforgiving process. The key word is that it is a 'PROCESS', and not a machine. The P&P machine simply facilitates a complex and unforgiving process.

What I cannot wrap my head around is the interest in a 'hobby' P&P machine. The very nature of what the machine does makes it a commercial system. What hobbyist needs to make hundreds of PCBs' in a day? That is a business and a business (like mine) does not have time to fiddle around with a toy. You will go out of business trying to 'save' money with a consumer targeted solution. The Neoden4 is a barely passable machine and it costs $10k+ - well outside of the hobby range.

After reading about the N4 here on EEVBlog, I have very thankful that I don't own one. Too limited and too fiddly.

If I had money burning a hole in my pocket and a lot of extra time - designing and building one sure would be fun. As long as I don't have to make a business out of it.
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #148 on: May 24, 2016, 06:34:04 am »
I spent some of Maker Faire on the OpenPNP booth this weekend. There was a LOT of interest in the machine being demoed, which was a pretty basic setup feeding from tape strips on the bed, but with top & bottom vision (and using vision to detect tape holes).

Afterwards Jason told me that if he'd had kits available at about $2500 he could probably have shifted a couple of dozen  (BOM cost around $900, target spec 0402/0.5mm QFP)
Now I'm sure that a lot of those potential customers would have only later realised the time to set up would be marginally worthwhile, and I wasn't around enough to hear many of the conversations, but I was quite surprised at the level of interest.
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #149 on: May 24, 2016, 07:19:10 am »
Quote from: rx8pilot on May 24, 2016, 03:24:25 am
What I cannot wrap my head around is the interest in a 'hobby' P&P machine. The very nature of what the machine does makes it a commercial system. What hobbyist needs to make hundreds of PCBs' in a day? That is a business and a business (like mine) does not have time to fiddle around with a toy. You will go out of business trying to 'save' money with a consumer targeted solution. The Neoden4 is a barely passable machine and it costs $10k+ - well outside of the hobby range.
Personally I don't think a hobbieists needs a high cph machine or a super duper 100% reliable machine 24/7. Small starting one person businesses as yourself might as long as they don't sell >100 pcb's a week that is an ideal market for these cheap machines. If you have a real business like >200 pcb's a week, I do not understand why you do not outsource this to professionals where the whole process is certified and the chance on productfailures is kept to a minimum. Why bother yourself any longer, economicially it does not compute.
So there is this grey area between high production and manual production where these machines fit.

But I guess what a hobbieist that makes 2 to 10 pcbs a week really needs is a faster manual camera assisted placer.
Especially when people get older there is a need for a mechanised system that can reliably pick up an extremely small smt part or very large high pincount device and be able to place it on the exact right spot on the pcb. Now there are little commercial manual p&p camera assited systems with a decent price and optimizing that further would be a nice market I guess.

I do agree, spending $100 or more on just one feeder, needing at least 80 or so of them alone is not viable for a hobby market.
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #150 on: May 24, 2016, 07:04:43 pm »
and then there is just those who want to do it, becuase tey can.
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Re: New Pick and Place design ideas
« Reply #151 on: May 24, 2016, 07:45:09 pm »
Quote from: mikeselectricstuff on May 24, 2016, 06:34:04 am
I spent some of Maker Faire on the OpenPNP booth this weekend. There was a LOT of interest in the machine being demoed, which was a pretty basic setup feeding from tape strips on the bed, but with top & bottom vision (and using vision to detect tape holes).

How does it deal with clear plastic tape?
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #152 on: May 24, 2016, 07:59:20 pm »
Quote from: mrpackethead on May 24, 2016, 07:04:43 pm
and then there is just those who want to do it, becuase tey can.

I wish I was in that camp. Currently struggling with business making hobbies a super low priority. All work, no play for me.  :--
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #153 on: May 24, 2016, 11:09:09 pm »
Quote from: rx8pilot on May 24, 2016, 07:45:09 pm
Quote from: mikeselectricstuff on May 24, 2016, 06:34:04 am
I spent some of Maker Faire on the OpenPNP booth this weekend. There was a LOT of interest in the machine being demoed, which was a pretty basic setup feeding from tape strips on the bed, but with top & bottom vision (and using vision to detect tape holes).

How does it deal with clear plastic tape?
Not sure but there would probably still be enough contrast at the hole edge, and if the tape is clear you should be able to image the part
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Offline Corporate666

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Re: New Pick and Place design ideas
« Reply #154 on: May 25, 2016, 03:30:49 am »
Quote from: Kjelt on May 24, 2016, 07:19:10 am
Personally I don't think a hobbieists needs a high cph machine or a super duper 100% reliable machine 24/7. Small starting one person businesses as yourself might as long as they don't sell >100 pcb's a week that is an ideal market for these cheap machines. If you have a real business like >200 pcb's a week, I do not understand why you do not outsource this to professionals where the whole process is certified and the chance on productfailures is kept to a minimum. Why bother yourself any longer, economicially it does not compute.
So there is this grey area between high production and manual production where these machines fit.

I would respectfully disagree with the above.

I think any PnP machine must be super reliable.  Even a relatively small PCB is going to have dozens of parts on it, and a multiple of that number worth of pads.  If you achieve 99% reliability, you're still looking at having something go wrong just about with every board.  I've placed countless thousands of boards with my PnP machines and my gut feel is that maybe once in 30-40 hours or operation I will need to do something (other than re-loading tapes, I mean).  For example... a nozzle gets clogged with solder paste and picks unreliably, or I notice parts are being placed a fraction of a millimeter off and I shut off and re-home the machine.  With some of my previous machines, I was lucky to get more than 20 minutes of reliable running before I had to futz with the machine, and that is when it became a deal breaker for me.  If the machine can't run for at least a matter of hours without problems, then it doesn't help me be more productive.  Loading boards in/out is one thing (takes literally seconds) but hearing the dreaded error beep and stopping everything else to fix the machine destroys productivity.  I realize that is a commercial environment but for home-brew stuff it's just as bad IMO.  If you can't be comfortable going away and doing something else, then you may as well put on some music and place by hand.

As for PnP'ing in-house vs outsourcing, I have done both and I am so so happy I have a PnP.  There are lots of benefits, but the main two are that I can make what I need when I need it without waiting, and second that I save HUGE on costs.  On the first one... I can run off 500 PCB's this week and another 300 next month or whenever I need them.  From start to finish it takes me a few hours to do the same work a board house would do.   The Chinese PCB assembly shop I used to use charged $0.0125 per SMD pad.  My boards are virtually all SMD.  With a couple of SOIC's, a MCU, some SOT's and 2 or 3 dozen passives, you are *easily* at 200 pads, so $2.50 per board for assembly.  So those 500 boards I can run off in a few hours would cost me $1,250.  And 200 pads is a pretty small board.  And from start to finish I am done by the afternoon, whereas with outsourced assembly, I am waiting days or 2-3 weeks if using a Chinese shop - and domestic assemblers are way, way more expensive than Chinese.  That 200 pad board would be more like $10/ea in my experience domestically, so that one run of 500 boards pays for half a good used PnP machine.

The other issue is cost.  I guess like most companies, I standardize on parts for dividers, biasing resistors, decoupling caps and even microcontrollers, regulators and switches.  I keep those parts loaded in the machine and I get economies of scale in using the same parts over multiple products.  If I needed 500pcb's that used a specific regulator, I would be buying a reel of 2,000 regulators to send to that assembler, and the other 1,500 just sit there waiting for my next board run.  Doing it in-house means I can buy partial reels from Digikey or Mouser as I need, and/or I can split that reel of 2,000 regulators across 7 different PCB designs that use the same regulator. 

Lastly (sorry for the length), it lets me do unorthodox stuff with my PCB's that assemblers might complain about.  I've pick and placed through hole stuff, silkscreened in paste to through holes, put resistors underneath other components like switches or between the pins of a connector on a high density board, violated board design rules when it suits me, had board outlines go through PTH component holes and such.  Since I know my process and my machines and I am machining the housings and all of that, I can do such "cowboy board design" stuff and get away with it when I need to solve a difficult engineering challenge.  But such stuff was always an issue when we outsourced boards and had to explain what we were doing and why and then listen to the grumbling from the PCB assembler about it.
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #155 on: May 25, 2016, 08:12:00 am »
Quote
I would respectfully disagree with the above.
Not a problem I love to be corrected by the people that do have the experience.
Still if I read your post I guess in my opinion you are not a small business or hobbieist so I would change my post with your info added to:

- Hobbieists still don't need a high cph machine or a super duper 100% reliable machine 24/7 for a few boards a week they can easily correct some mistakes the P&P made, every board is visually inspected anyway. Maybe then the only target audience for the low budget P&P machines that are discussed, but really they don't need them, it takes as much time to set the machine up as to do it by hand.

- small businesses with <100 boards a week are the target market for the medium priced PnP machines we are discussing ?

- (Semi) large businesses as yourself that do a couple of batches of 500 boards a week need to outsource or as you state own a pro machine because outsourcing is too expensive and inflexible.

So the semi-large business could best get a bankloan for $50k or more and buy a professional reliable machine with service contract and it earns itself back in a couple of years, right?
You can not buy a machine that we discuss frequently on this forum without full 24/7 service contract because if the machines is broke and you can't produce boards for a week you're loosing a lot of money.
Also it means buying more than just a P&P, you need an industrial grade reflow oven, you preferably also need a flying probe tester and a lot of small things that add up to the costs.

Pro boardhouses do more than just P&P they also do an end test of the pcb and devices with for instance a flying probe tester (also expensive machine).
They guarantee and insure their work, so for instance if the paste is bad or something else in the process goes wrong, they have to pay for it (perhaps some crappy board houses won't, but the good ones do).


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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #156 on: May 25, 2016, 09:54:38 am »
everyone needs to find there own space and figure it out for their particular situation.

Foruantly there are a lot of options starting at $1000 with Jason and open PNP and going to $$$$$$$$$$$ with state of the art 1M pph lines.

There is no universal answer.
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Offline JuKu

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Re: New Pick and Place design ideas
« Reply #157 on: May 25, 2016, 12:26:26 pm »
Quote from: rx8pilot on May 24, 2016, 07:45:09 pm
Quote from: mikeselectricstuff on May 24, 2016, 06:34:04 am
I spent some of Maker Faire on the OpenPNP booth this weekend. There was a LOT of interest in the machine being demoed, which was a pretty basic setup feeding from tape strips on the bed, but with top & bottom vision (and using vision to detect tape holes).

How does it deal with clear plastic tape?
Probably just fine. This example is not from OpenPnP, but shows how machine vision can work with clear tapes. Spoiler: clear tape is not very clear.  http://www.liteplacer.com/phpBB/viewtopic.php?f=11&t=7&p=87&hilit=Vision+transparent#p81
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Offline Corporate666

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Re: New Pick and Place design ideas
« Reply #158 on: May 25, 2016, 11:01:20 pm »
Quote from: Kjelt on May 25, 2016, 08:12:00 am
- Hobbieists still don't need a high cph machine or a super duper 100% reliable machine 24/7 for a few boards a week they can easily correct some mistakes the P&P made, every board is visually inspected anyway. Maybe then the only target audience for the low budget P&P machines that are discussed, but really they don't need them, it takes as much time to set the machine up as to do it by hand.

- small businesses with <100 boards a week are the target market for the medium priced PnP machines we are discussing ?

- (Semi) large businesses as yourself that do a couple of batches of 500 boards a week need to outsource or as you state own a pro machine because outsourcing is too expensive and inflexible.

I think that $10k buys a person a working and easy-to-use second-hand machine like the Quad's that I have.  Such a machine will be much more capable than anything home-made or designed for hobbyists, largely because all the bugs are worked out.  I can't imagine having to fix 10 mistakes on a board with 1,000 components on it.  It would take so long visually scanning the board and trying to find mistakes that it would drive me crazy.  And from experience, it takes 20 times as long to fix a board after reflow than to fix it before.  If a hobbyist is doing a few boards a week, I don't think any PnP is worthwhile at all.  The time required to set it up, load parts in, program it and all of that would make it not worthwhile at all, IMO.

Quote
So the semi-large business could best get a bankloan for $50k or more and buy a professional reliable machine with service contract and it earns itself back in a couple of years, right?
You can not buy a machine that we discuss frequently on this forum without full 24/7 service contract because if the machines is broke and you can't produce boards for a week you're loosing a lot of money.
Also it means buying more than just a P&P, you need an industrial grade reflow oven, you preferably also need a flying probe tester and a lot of small things that add up to the costs.

Pro boardhouses do more than just P&P they also do an end test of the pcb and devices with for instance a flying probe tester (also expensive machine).
They guarantee and insure their work, so for instance if the paste is bad or something else in the process goes wrong, they have to pay for it (perhaps some crappy board houses won't, but the good ones do).

There is a huge gap IMO between the hobbyist level you are describing above and the "get a loan, a reflow oven and a flying probe tester" level.  I have made hundreds of thousands of boards.  We paste them on a square of polypropylene plastic screwed to a desk.  I take a few old PCB's and tape them to the plastic, then tape the stencil on top on one edge.  Then just load a board in and paste it, then another.  We have pasted countless thousands of boards this way and it works great.  I can paste 500 boards in 20 minutes with zero problems (maybe once every month a pad doesn't get pasted, takes 10 seconds to put paste on with the manual dispenser).

For reflow, I use a toaster oven.  Not even with any type of controller.  Just a standard convection toaster oven.  We've reflowed countless thousands of boards in it without any problems.   We don't do any flying probe testing.  We may make a test program that's loaded into the device to test it or (99% of the time) just test it's function while still in the panel using the production program.  We program the chips with Pomona test clips.  Takes literally 3-4 seconds to program each board this way.

The failure rate is maybe 1 in 200 boards, and 99% of the time it's a component that shifted during reflow. 

Bad batches of solder paste and boards that fail test are just total non-issues for us.  As for the PnP machine itself, I've owned them for maybe 4 years and the only problems I have had was a nozzle clogged with solder paste (a maintenance issue), the occasional feeder that gets 'sticky', and the door interlock came off and caused the machine to alarm out (checked the manual, realized the problem, fixed in 5 minutes).

I spent maybe 3-4 days per month placing boards and I can do a couple thousand boards in that time.  If the machine breaks, I usually can fix it myself and if not, I don't need a service contract, just call the company and they will tell me what's likely wrong and what part I need, or I can schedule a service visit.


There's just a huge gap between the hobby guy who needs to do a few boards a week and a company that needs a full SMT line with service contracts and the like.  And that huge gap is served perfectly by used machinery.  That used machinery costs the same as what these hobbyist machines cost, but it performs a hundred times better at least.

I just honestly don't see any use for this home brew stuff.  It's sort of like building your own car.  You can buy a used car so cheap that it makes no sense to build one and while a used car can be a money pit, the amount you end up spending to build your own is well into the territory of buying a slightly used late model car that will do everything better.

Just my experience.  I am not anti-home brew/hobbyist.  I spent years chasing this dream myself.  I built my own PnP machine, I retrofitted a pro machine with bad electronics using my own motor drivers and software.  And I bought numerous used machines.  None of it makes any sense when you can get a great used machine for $10k that can support high hundreds of thousands if not millions per year in sales worth of circuit board assembly needs. 
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #159 on: May 25, 2016, 11:09:10 pm »
[quote author=Corporate666 link=topic=67734.msg948940#msg948940 date=1464217280

I think that $10k buys a person a working and easy-to-use second-hand machine like the Quad's that I have.  Such a machine will be much more capable than anything home-made or designed for hobbyists, largely because all the bugs are worked out.  I can't imagine having to fix 10 mistakes on a board with 1,000 components on it.  It would take so long visually scanning the board and trying to find mistakes that it would drive me crazy.  And from experience, it takes 20 times as long to fix a board after reflow than to fix it before.  If a hobbyist is doing a few boards a week, I don't think any PnP is worthwhile at all.  The time required to set it up, load parts in, program it and all of that would make it not worthwhile at all, IMO.


Quote

We went down a similar path, and bought some 2nd hand Yamahas.. a bit more than $10k, the entire scenerio ended up costing about $60k, but we have two machines,  and a good multizone oven,  and Lot sof feeders..      The cost recovery for me is about 6 months, but i'm able to do stuff in ways i was'nt able to before, so that also happens.. 

As for hobbiest.  I think its ok as well..   Its a hobby.. people do jigsaw puzzles for no reason other than to do them.   If they want to do PnP because its a hobby then surely thats ok..  People easily spend $10k a year chasiing a small white ball around the grass field.. What ever spins your wheels.



Quote
So the semi-large business could best get a bankloan for $50k or more and buy a professional reliable machine with service contract and it earns itself back in a couple of years, right?
You can not buy a machine that we discuss frequently on this forum without full 24/7 service contract because if the machines is broke and you can't produce boards for a week you're loosing a lot of money.
Also it means buying more than just a P&P, you need an industrial grade reflow oven, you preferably also need a flying probe tester and a lot of small things that add up to the costs.

Pro boardhouses do more than just P&P they also do an end test of the pcb and devices with for instance a flying probe tester (also expensive machine).
They guarantee and insure their work, so for instance if the paste is bad or something else in the process goes wrong, they have to pay for it (perhaps some crappy board houses won't, but the good ones do).

There is a huge gap IMO between the hobbyist level you are describing above and the "get a loan, a reflow oven and a flying probe tester" level.  I have made hundreds of thousands of boards.  We paste them on a square of polypropylene plastic screwed to a desk.  I take a few old PCB's and tape them to the plastic, then tape the stencil on top on one edge.  Then just load a board in and paste it, then another.  We have pasted countless thousands of boards this way and it works great.  I can paste 500 boards in 20 minutes with zero problems (maybe once every month a pad doesn't get pasted, takes 10 seconds to put paste on with the manual dispenser).

For reflow, I use a toaster oven.  Not even with any type of controller.  Just a standard convection toaster oven.  We've reflowed countless thousands of boards in it without any problems.   We don't do any flying probe testing.  We may make a test program that's loaded into the device to test it or (99% of the time) just test it's function while still in the panel using the production program.  We program the chips with Pomona test clips.  Takes literally 3-4 seconds to program each board this way.

The failure rate is maybe 1 in 200 boards, and 99% of the time it's a component that shifted during reflow. 

Bad batches of solder paste and boards that fail test are just total non-issues for us.  As for the PnP machine itself, I've owned them for maybe 4 years and the only problems I have had was a nozzle clogged with solder paste (a maintenance issue), the occasional feeder that gets 'sticky', and the door interlock came off and caused the machine to alarm out (checked the manual, realized the problem, fixed in 5 minutes).

I spent maybe 3-4 days per month placing boards and I can do a couple thousand boards in that time.  If the machine breaks, I usually can fix it myself and if not, I don't need a service contract, just call the company and they will tell me what's likely wrong and what part I need, or I can schedule a service visit.


There's just a huge gap between the hobby guy who needs to do a few boards a week and a company that needs a full SMT line with service contracts and the like.  And that huge gap is served perfectly by used machinery.  That used machinery costs the same as what these hobbyist machines cost, but it performs a hundred times better at least.

I just honestly don't see any use for this home brew stuff.  It's sort of like building your own car.  You can buy a used car so cheap that it makes no sense to build one and while a used car can be a money pit, the amount you end up spending to build your own is well into the territory of buying a slightly used late model car that will do everything better.

Just my experience.  I am not anti-home brew/hobbyist.  I spent years chasing this dream myself.  I built my own PnP machine, I retrofitted a pro machine with bad electronics using my own motor drivers and software.  And I bought numerous used machines.  None of it makes any sense when you can get a great used machine for $10k that can support high hundreds of thousands if not millions per year in sales worth of circuit board assembly needs. 

- small businesses with <100 boards a week are the target market for the medium priced PnP machines we are discussing ?

- (Semi) large businesses as yourself that do a couple of batches of 500 boards a week need to outsource or as you state own a pro machine because outsourcing is too expensive and inflexible.
[/quote]

I think that $10k buys a person a working and easy-to-use second-hand machine like the Quad's that I have.  Such a machine will be much more capable than anything home-made or designed for hobbyists, largely because all the bugs are worked out.  I can't imagine having to fix 10 mistakes on a board with 1,000 components on it.  It would take so long visually scanning the board and trying to find mistakes that it would drive me crazy.  And from experience, it takes 20 times as long to fix a board after reflow than to fix it before.  If a hobbyist is doing a few boards a week, I don't think any PnP is worthwhile at all.  The time required to set it up, load parts in, program it and all of that would make it not worthwhile at all, IMO.

Quote
So the semi-large business could best get a bankloan for $50k or more and buy a professional reliable machine with service contract and it earns itself back in a couple of years, right?
You can not buy a machine that we discuss frequently on this forum without full 24/7 service contract because if the machines is broke and you can't produce boards for a week you're loosing a lot of money.
Also it means buying more than just a P&P, you need an industrial grade reflow oven, you preferably also need a flying probe tester and a lot of small things that add up to the costs.

Pro boardhouses do more than just P&P they also do an end test of the pcb and devices with for instance a flying probe tester (also expensive machine).
They guarantee and insure their work, so for instance if the paste is bad or something else in the process goes wrong, they have to pay for it (perhaps some crappy board houses won't, but the good ones do).

There is a huge gap IMO between the hobbyist level you are describing above and the "get a loan, a reflow oven and a flying probe tester" level.  I have made hundreds of thousands of boards.  We paste them on a square of polypropylene plastic screwed to a desk.  I take a few old PCB's and tape them to the plastic, then tape the stencil on top on one edge.  Then just load a board in and paste it, then another.  We have pasted countless thousands of boards this way and it works great.  I can paste 500 boards in 20 minutes with zero problems (maybe once every month a pad doesn't get pasted, takes 10 seconds to put paste on with the manual dispenser).

For reflow, I use a toaster oven.  Not even with any type of controller.  Just a standard convection toaster oven.  We've reflowed countless thousands of boards in it without any problems.   We don't do any flying probe testing.  We may make a test program that's loaded into the device to test it or (99% of the time) just test it's function while still in the panel using the production program.  We program the chips with Pomona test clips.  Takes literally 3-4 seconds to program each board this way.

The failure rate is maybe 1 in 200 boards, and 99% of the time it's a component that shifted during reflow. 

Bad batches of solder paste and boards that fail test are just total non-issues for us.  As for the PnP machine itself, I've owned them for maybe 4 years and the only problems I have had was a nozzle clogged with solder paste (a maintenance issue), the occasional feeder that gets 'sticky', and the door interlock came off and caused the machine to alarm out (checked the manual, realized the problem, fixed in 5 minutes).

I spent maybe 3-4 days per month placing boards and I can do a couple thousand boards in that time.  If the machine breaks, I usually can fix it myself and if not, I don't need a service contract, just call the company and they will tell me what's likely wrong and what part I need, or I can schedule a service visit.


There's just a huge gap between the hobby guy who needs to do a few boards a week and a company that needs a full SMT line with service contracts and the like.  And that huge gap is served perfectly by used machinery.  That used machinery costs the same as what these hobbyist machines cost, but it performs a hundred times better at least.

I just honestly don't see any use for this home brew stuff.  It's sort of like building your own car.  You can buy a used car so cheap that it makes no sense to build one and while a used car can be a money pit, the amount you end up spending to build your own is well into the territory of buying a slightly used late model car that will do everything better.

Just my experience.  I am not anti-home brew/hobbyist.  I spent years chasing this dream myself.  I built my own PnP machine, I retrofitted a pro machine with bad electronics using my own motor drivers and software.  And I bought numerous used machines.  None of it makes any sense when you can get a great used machine for $10k that can support high hundreds of thousands if not millions per year in sales worth of circuit board assembly needs.
[/quote]
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #160 on: May 25, 2016, 11:19:45 pm »
Quote from: JuKu on May 25, 2016, 12:26:26 pm
Quote from: rx8pilot on May 24, 2016, 07:45:09 pm
How does it deal with clear plastic tape?
Probably just fine. This example is not from OpenPnP, but shows how machine vision can work with clear tapes. Spoiler: clear tape is not very clear.  http://www.liteplacer.com/phpBB/viewtopic.php?f=11&t=7&p=87&hilit=Vision+transparent#p81

Wow, amazing contrast. I know it's not super clear, but now I can see the proof. Excellent.
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Offline Corporate666

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Re: New Pick and Place design ideas
« Reply #161 on: May 26, 2016, 03:21:13 am »
Quote from: mrpackethead on May 25, 2016, 11:09:10 pm
We went down a similar path, and bought some 2nd hand Yamahas.. a bit more than $10k, the entire scenerio ended up costing about $60k, but we have two machines,  and a good multizone oven,  and Lot sof feeders..      The cost recovery for me is about 6 months, but i'm able to do stuff in ways i was'nt able to before, so that also happens.. 

As for hobbiest.  I think its ok as well..   Its a hobby.. people do jigsaw puzzles for no reason other than to do them.   If they want to do PnP because its a hobby then surely thats ok..  People easily spend $10k a year chasiing a small white ball around the grass field.. What ever spins your wheels.

Sorry, it looks like the quotes got messed up - I apologize if I did not quote your post correctly.

I totally agree with you on the above, and I hope it didn't sound like I am poo-poo'ing someone who chooses to build a home brew PnP because it's interesting or fun for them.  Two areas of electronics I LOVE are lighting and motion, so I can totally see the appeal of doing something custom.

I am not sure why noobies gravitate to the incorrect aspects of pick and placing.  I did the same thing.  I remember when we bought our first real CNC machine.  I was enamored with how this giant hunk of iron and steel moved so fast and so accurately.  Way more accurately (I imagined) than a PnP needed to.  Yet this machine cost $50k... so I assumed a PnP would cost maybe $10k.  I looked into PnP prices and I was absolutely floored - it was a Philips (Topaz or Emerald - really nice back in the day) and IIRC it was in the $350k range (new).  I was sure it was an absolute ripoff due to low volumes of sales.  So I started looking at building my own.  The trick, I found, with PnP was not making an accurate machine... but rather that there are lots of processes a PnP needs to do that a milling machine doesn't.  Feeding components, vision/adjustment, rotation, placements against a flexing panel, and so much more.  And it has to do it really fast and with a super low failure rate.  It's all those little details that make it really hard.  I quickly realized I had been a bit (more than a bit) arrogant in thinking I could jump in and solve the problems that countless of thousands of engineers had worked on before me. 

But I definitely learned a ton tinkering with that stuff, so to each his own.
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #162 on: May 26, 2016, 04:11:48 am »
For interest, here is some bottom images that are part of openPnp.

The camera is set up indentically for both parts, one is an 0805 ceramic cap, the other a 0.5mm pitch TQFP-64

These are using a $45 USB camera.

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Re: New Pick and Place design ideas
« Reply #163 on: May 26, 2016, 06:22:16 am »
Quote from: Corporate666 on May 20, 2016, 07:50:03 am
  Etched steel stencils without frames and pasted on a desk using masking tape to hold boards in place can support multi-million per-year operations.  We can paste 500 boards (50 panels, 10 PCB/panel) in maybe 20 minutes. And we can place them in maybe 2 hours.  And reflow in about 30 minutes.  There is zero economy to be gained with paste dispensing.  The only exception is prototype boards or glue dispensing for wave soldering, but those are specialized applications.  And even then, given the time to program the machine, I've never had a case where it wasn't faster to just do it with the desktop pedal-operated dispenser.

In my specific case, programming the P&P machine also programs the paste dispenser.   The additional time necessary to set up a board for dispensing is about 30 seconds.  (Click on paste, create paste records from placement records, click on a couple of options, click done.  enter 8 numbers to tell the paste dispenser, and click on done).   

BUT, I agree... I'd rather stencil.   We very quickly move from dispense to stencil just because of defect reduction.... unfortunately, some boards just don't have high enough volume for a framed stencil.  Which is why I want to ask you about the process above.  Do you have some pictures and/or more details to describe?  Did you re-tape at each changeover?  Did you just use 'painters tape' or have you tried something else (aluminum foil or kapton tape, etc)?

I'm thinking that for my lower volume products I might be able to do something similar, but using a piece of 3/4 MDF as a base so we can avoid re-taping and re-aligning each time.   Make one for each board type, and keep them between uses.
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #164 on: May 26, 2016, 07:51:03 am »
Quote from: Corporate666 on May 25, 2016, 11:01:20 pm
There is a huge gap IMO between the hobbyist level you are describing above and the "get a loan, a reflow oven and a flying probe tester" level.
Yes I put three steps, it could be four or more, but I do agree.

Quote
I think that $10k buys a person a working and easy-to-use second-hand machine like the Quad's that I have.  Such a machine will be much more capable than anything home-made or designed for hobbyists, largely because all the bugs are worked out.
Again I agree, if you get it working it is really nice. There is just a risk that some parts will not be available in the near future anymore and you have to be innovative to come up with a solution. Or other problems arise since the machine was build a long time ago, such as the 0204 feeder problems (half step needed, only full step available) that rx8pilot now encounters. If there are new parts coming out of the factories you need to come up with new solutions, nothing insurmountable probably but still takes time so you ARE at that moment busy with building and adapting your own custom solutions for your machine  ;)

Quote
I have made hundreds of thousands of boards.
Ok then I really really do not understand the following:

Quote
For reflow, I use a toaster oven.  Not even with any type of controller.  Just a standard convection toaster oven.
You must be kidding right? Have you at least temp. profiled the oven to see if it matches the reflow profile of the parts and paste?
The risk of microcracking, over or underheating or uneven temp zoning causing bad contacts is huge with a standard oven. Most can not even handle the temperature curve needed (too steep).
Rohs leadfree paste is even more difficult.
Even I , a hobbieist that does at most 50 boards a year have a 2nd hand semi professional reflow oven bought cheaply from a business that outsourced (new price $2k to $3k) and I do not even make money of this or a business it is just hobby.
I can't believe you run a business with this kind of equipment, I don't know what to say, for a few k$ you can have a really nice good controlled reflow oven, is the profit of the business that bad or do you just not care if your products could fail in a few years due to microcracking or overheating? Maybe I am misinformed or overexaggerating, but for what I have read this is really a big no go concerning reliability and product lifetime.

Quote
If the machine breaks, I usually can fix it myself and if not, I don't need a service contract, just call the company and they will tell me what's likely wrong and what part I need, or I can schedule a service visit.
If you have stock to compensate production outage that is not a problem. If you have a customer that paid you to deliver the order at a penalty in the contract of each day delay that is different ballgame.

Quote
I just honestly don't see any use for this home brew stuff.  It's sort of like building your own car. 
I agree, a hobbieist does not need it, nice to have, they don't run production numbers that ratify such an investment, still there are hobbieists that own equipment better than some pro's do, think about photography and such. So if there is a market why not serve it, hence the chinese machines we see so many on this forum.

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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #165 on: May 26, 2016, 04:10:15 pm »
Quote from: Kjelt on May 26, 2016, 07:51:03 am
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I think that $10k buys a person a working and easy-to-use second-hand machine like the Quad's that I have.  Such a machine will be much more capable than anything home-made or designed for hobbyists, largely because all the bugs are worked out.
Again I agree, if you get it working it is really nice. There is just a risk that some parts will not be available in the near future anymore and you have to be innovative to come up with a solution. Or other problems arise since the machine was build a long time ago, such as the 0204 feeder problems (half step needed, only full step available) that rx8pilot now encounters. If there are new parts coming out of the factories you need to come up with new solutions, nothing insurmountable probably but still takes time so you ARE at that moment busy with building and adapting your own custom solutions for your machine  ;)

Some clarification on this point.....Every single part of my machine is still supported and available from PPM and a few other sources. Nozzles, belts, rollers, PCB's, etc. That was one of the most critical considerations when I chose to buy it - I had no time to buy an off grid system where I was totally on my own. I have repaired a ton of things on my own, machined special fixtures and wrote some interface scripts - but PPM has been CRITICAL to my success, both in parts supply and troubleshooting setup problems.

Case in point: The PPM owner called me after seeing a post I made on another forum about the 2mm indexing problem. He showed me how the software supports a 'double pickup' with 4mm index feeders to accommodate 2mm pitch tapes - DONE! I had found a bunch of feeders on eBay that are precise enough for 0402/0201 but only index 4mm. The solution was there and I didn't even know it. PPM unlocked the mystery.

So far, I am just a pinch under $10k, and a few weeks of labor and learning.
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Offline Corporate666

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Re: New Pick and Place design ideas
« Reply #166 on: May 26, 2016, 11:49:59 pm »
Quote from: forrestc on May 26, 2016, 06:22:16 am
BUT, I agree... I'd rather stencil.   We very quickly move from dispense to stencil just because of defect reduction.... unfortunately, some boards just don't have high enough volume for a framed stencil.  Which is why I want to ask you about the process above.  Do you have some pictures and/or more details to describe?  Did you re-tape at each changeover?  Did you just use 'painters tape' or have you tried something else (aluminum foil or kapton tape, etc)?

I'm thinking that for my lower volume products I might be able to do something similar, but using a piece of 3/4 MDF as a base so we can avoid re-taping and re-aligning each time.   Make one for each board type, and keep them between uses.

I don't have any pics handy but I can describe.

We have a "pasting station" at work.  It's just a standard 4 foot desk.  I buy 24" x 24" x 0.5" pieces of polyproplyene.  I use PP because it's just about the cheapest plastic... polyethylene is cheaper but too slippery for the tape to stick.  Anything less than 0.5" thickness means the plastic will likely be quite warped before you get it.

I have tons of old PCB's lying around of various sizes/shapes/thicknesses.  I just put the panel to be pasted on the plastic sheet, then place some PCB's around it, making sure I am tight against the corners so the board can't move.  Then I use blue painters tape to stick them down.  My stencils usually have 4-5" of free space around the actual openings, so I make sure to build a big enough 'platform' to support the whole stencil.

I secure the stencil in place with a strip of painters along the top side.  Then scoop a blob of paste from the container onto the top of the stencil and silkscreen the board.  I have perfected a "flick" maneuver at the end of each pasting stroke which keeps the paste on the blade after pasting.  Then I have a little scrap piece of steel and I scrape the paste off the pasting blade back onto the top of stencil in a blob.  Then lift the stencil up a little (with blob of paste at top - but it's close to the pivot point so no problem), grab the board using a pair of pliers and set it aside, put another one in and drop the stencil back down - I also check the panel I just pasted to make sure it's all good.  I always get my boards gold plated since the contrast between gold and solder paste is easy to see, making any un-pasted pads stand out.

Sometimes, maybe after every 20-30 panels, the piece of tape at the top of the stencil gets worn out from using it as a hinge and registration between stencil and board gets off.  I just peel off the tape, clean that area of the stencil with acetone and re-apply.

When I am done, the leftover paste goes back in the tub, and I immediately clean off the stencils with acetone from a spray bottle, a toothbrush and cloths. 

I have several of these 24x24 plastic panels and I tend to have 2 setups on each one - one for the front and one for the rear of the PCB.  The only trick for doing the second side of the PCB's is the height of components from the first side, but I can stack PCB's or buy plastic shim stock from Mcmaster to get the height perfect for 2nd sides of PCB's.

Maybe once every 1 or 2 thousand panels pasted, I will take my fixture/holder off the plastic panel, clean it off with acetone and re-build the fixture.  But that's just because I am a neat freak and hate seeing dried blobs of paste on the plastic panels.

I don't do much pasting myself anymore, but I have shown maybe 6 or 7 people here how to do it, and within a couple of boards, they get it down perfect.

Nowadays I get my stencils from my PCB fab in China, but I have used Stencils Unlimited - $150 for the frameless ones I use.  I have also used OSHstencils kapton prototype stencils on this same setup.  Works fine too.

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Offline Corporate666

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Re: New Pick and Place design ideas
« Reply #167 on: May 27, 2016, 12:29:30 am »
Quote from: Kjelt on May 26, 2016, 07:51:03 am
You must be kidding right? Have you at least temp. profiled the oven to see if it matches the reflow profile of the parts and paste?

I haven't temp profiled the oven.  I bought one that was recommended years ago by someone who was selling some sort of controller and tested some ovens to see which worked best.  But if you buy the right kind of oven, most of them are fine.

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The risk of microcracking, over or underheating or uneven temp zoning causing bad contacts is huge with a standard oven. Most can not even handle the temperature curve needed (too steep).

Based on what data?  The boards reflow evenly with very little time difference between the first and last part of the board to reflow.  The trick is to use an oven with multiple elements and it has to be a convection oven.  I don't know of anyone who has done any serious testing or analysis on using toaster ovens, so the above concerns are greatly overstated.

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I can't believe you run a business with this kind of equipment, I don't know what to say, for a few k$ you can have a really nice good controlled reflow oven, is the profit of the business that bad or do you just not care if your products could fail in a few years due to microcracking or overheating? Maybe I am misinformed or overexaggerating, but for what I have read this is really a big no go concerning reliability and product lifetime.

Yes, you are misinformed and exaggerating.  I have a bench top reflow oven.  It sucks.  It heats unevenly, it isn't consistent and it produces inferior results to the toaster oven.  I also had a 10 zone Heller 480V reflow oven that I got just about for free that was a year old and with less than 100 hours on it.  The amount of time it takes to set up, tweak, adjust and mess with it wasn't worth it.  We get overall superior results using a toaster oven.  We've reflowed hundreds of thousands of boards spanning 15 years, offer lifetime warranties and out of the maybe 30 failed units I get back each year, in just about every case the problem is physical damage or water damage.  If you're not using new paste that you store in a fridge and throw away the unused amount after you open it... and if you don't store all your components in temperature and humidity controlled environments... then focusing on reflowing with a toaster oven is being chicken little.

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If you have stock to compensate production outage that is not a problem. If you have a customer that paid you to deliver the order at a penalty in the contract of each day delay that is different ballgame.

You're not listening to what I am saying...  there is a huge huge area between a guy doing hobby work and a large company with a full SMT line(s).  The people and companies that occupy that gap are not running their PnP machines every day.  They do not do contract manufacturing.  They are not doing JIT manufacturing.  Most companies aren't doing JIT manufacturing.  Service contracts are not needed.  All that is needed is the ability to get service when it is needed.  I have that.  I do have customers that we have to deliver to with built-in penalties, and service contracts or the lack thereof don't add anything or harm anything in that regard.  I am challenging your worldview that there are 3 categories of people - hobbyists, big companies running SMT lines, and "everyone else" who should be outsourcing.  I know numerous companies in my area and elsewhere who are making from hundreds to maybe several thousand PCB's per year and they are doing it just like I am doing it and making a good living at it. 

Quote
I agree, a hobbieist does not need it, nice to have, they don't run production numbers that ratify such an investment, still there are hobbieists that own equipment better than some pro's do, think about photography and such. So if there is a market why not serve it, hence the chinese machines we see so many on this forum.

I am not suggesting that hobbyists shouldn't buy PnP machines because they don't need them.  My position is that all of these hobby-level PnP machines are vastly inferior to buying a used machine that is still supported and was built as a pro level machine. 

This is a Quad 4C placing parts.



There is one on eBay now for $10k.  A more realistic price is probably $5-7k for the machine - that's what they sell for in working condition with feeders.  Not everyone can fit a machine like that in their basement, but other than for people who just don't have the space or who just like to tinker with stuff because they enjoy it, I don't see the value in the home-brew PnP machines. 
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #168 on: May 27, 2016, 12:37:57 am »

My $90 oven + Sparkfun Controller ( no longer avaialable ) works brillantly, and yes, i've profiled it and its every bit as good ( result wise ) as the expensive multizone oven we have in teh factory.. And it takes about 10 seconds to start, versus 45 minutes.   It uses just 4kW, vs 12kw. 

It just does't work for doing 10000's of boards.. 
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #169 on: May 27, 2016, 12:40:19 am »
Yamaha YX100's with no feeders are going for about $10-15k, in various states of repair..    Just be prepared for some work to get them back to to "sweet"
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Re: New Pick and Place design ideas
« Reply #170 on: May 27, 2016, 12:57:01 am »
Quote from: Corporate666 on May 27, 2016, 12:29:30 am
There is one on eBay now for $10k.  A more realistic price is probably $5-7k for the machine - that's what they sell for in working condition with feeders.  Not everyone can fit a machine like that in their basement, but other than for people who just don't have the space or who just like to tinker with stuff because they enjoy it, I don't see the value in the home-brew PnP machines.

That machine does not have feeders. Even if you get a great deal on feeders, it would be at least double. That also assumes the machine is in great shape and works out of the box - mine was advertised as READY TO GO which was not even close to being true. Since it was only $5k with about 55 feeders, I did not care. On top of that, it was local so I only spent $50 renting a trailer for shipping.


I use a JEM310 batch oven that is very good for what I do. Easy programming and very consistent. Personally, I would be scared of the toaster oven setup if only as a precaution. My products are in a critical role and operate all over the world in remote locations. A huge amount of my work is reliability and longevity. I have read a lot about the soldering process and it scared me enough to get a tightly controlled oven. No way for me to know without lab testing, which I have not done. The profile I use very closely matches the recommendations.

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Re: New Pick and Place design ideas
« Reply #171 on: May 27, 2016, 05:09:27 am »
Quote from: Kjelt on May 26, 2016, 07:51:03 am
You must be kidding right? Have you at least temp. profiled the oven to see if it matches the reflow profile of the parts and paste?
The risk of microcracking, over or underheating or uneven temp zoning causing bad contacts is huge with a standard oven. Most can not even handle the temperature curve needed (too steep).
Rohs leadfree paste is even more difficult.
Even I , a hobbieist that does at most 50 boards a year have a 2nd hand semi professional reflow oven bought cheaply from a business that outsourced (new price $2k to $3k) and I do not even make money of this or a business it is just hobby.
I can't believe you run a business with this kind of equipment, I don't know what to say, for a few k$ you can have a really nice good controlled reflow oven, is the profit of the business that bad or do you just not care if your products could fail in a few years due to microcracking or overheating? Maybe I am misinformed or overexaggerating, but for what I have read this is really a big no go concerning reliability and product lifetime.

I agree with Corporate666.... but I'm going to vote misinformed.

Microcracking generally is only an issue with moisture sensitive parts which haven't been stored correctly.   

As far as reflow profiles go, most boards just aren't that picky.   Most components just aren't that picky.   SAC305 is a bit of a pain, but still, fairly wide window with the newer paste chemistries.  As long as you are able to move from active paste to reflow within a reasonable amount of time - and then cooling at the proper time, you're golden.   Too slow and things don't want to melt because the solder has re-oxidized (after being cleaned) - too fast and the paste doesn't have time to work.   But most paste handles a wide range of slopes.   Of bigger concern is cooling time for grain formation.  But even that has a wide range of working slopes.
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Re: New Pick and Place design ideas
« Reply #172 on: May 27, 2016, 05:22:54 am »
Quote from: rx8pilot on May 27, 2016, 12:57:01 am
I use a JEM310 batch oven that is very good for what I do. Easy programming and very consistent. Personally, I would be scared of the toaster oven setup if only as a precaution. My products are in a critical role and operate all over the world in remote locations. A huge amount of my work is reliability and longevity. I have read a lot about the soldering process and it scared me enough to get a tightly controlled oven. No way for me to know without lab testing, which I have not done. The profile I use very closely matches the recommendations.

I use a batch oven myself - a toaster is a bit ghetto even for me...  for similar reasons you mentioned.    If it failed I'd probably replace it with something similar.  But not a high end conveyored oven (I have a low end one here collecting dust - anyone interested?)

However, having rebuilt this oven like 3 times over the years I've had it, and reengineered the profile countless times,  I've discovered that things are not as critical as one would be led to believe for most things.   I have built a relationship with a fair number of people in the solder and paste industry, and they have all generally told me the same thing:  As long as you get everything hot enough roughly at the same time, and don't take too long getting there (and pick the right paste), everything should be good.   Cooling is FAR MORE CRITICAL than the heating.   Which is sad since everyone focuses on the heating side, and it's not the critical part.

The nightmares people talk about in the industry are usually designs which have temperature sensitive small parts on a board right next to something with big thermal mass.   Some of the giant ceramic BGA packages are the worst.   Then the problem is that the ceramic package is still getting up to temperature while the poor little temperature sensitive part in a SOT23 is melting.

-forrest
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Offline JuKu

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Re: New Pick and Place design ideas
« Reply #173 on: May 27, 2016, 07:12:31 am »
Quote from: Corporate666 on May 26, 2016, 11:49:59 pm
Quote from: forrestc on May 26, 2016, 06:22:16 am
BUT, I agree... I'd rather stencil.   We very quickly move from dispense to stencil just because of defect reduction.... unfortunately, some boards just don't have high enough volume for a framed stencil.  Which is why I want to ask you about the process above.  Do you have some pictures and/or more details to describe?  Did you re-tape at each changeover?  Did you just use 'painters tape' or have you tried something else (aluminum foil or kapton tape, etc)?

I'm thinking that for my lower volume products I might be able to do something similar, but using a piece of 3/4 MDF as a base so we can avoid re-taping and re-aligning each time.   Make one for each board type, and keep them between uses.

I don't have any pics handy but I can describe.
...
And on this page, you can find the video, from which I learned the same technique: http://www.beta-estore.com/rkuk/order_product_details.html?p=13.
It really is as easy as Corporate666 says and the video makes it look.
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #174 on: May 27, 2016, 08:29:43 am »
I started out that way by placing other pcbs around the target pcb.
Since I don't make all my pcbs right away but only when and how many I need, I wanted a more flexible approach.
So i stick them to a piece of cut laminate floortile (see picture old).
It works but there was room for improvement which I found by milling the piece of laminate floortile with the correct depth and dimensions of the pcb and in one or two corners
some extra space to easily remove the pcb after (see picture new). \
It takes a bit more setup time (around half hour or so) if you have a normal decent mill but you have it available whenever you want/need it.
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Offline Koen

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Re: New Pick and Place design ideas
« Reply #175 on: May 27, 2016, 11:44:01 am »
Add two holes to the PCB and the stencil. Then index both with dowel pins. Simple, efficient and cheap.
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #176 on: May 27, 2016, 05:45:25 pm »
Quote from: Koen on May 27, 2016, 11:44:01 am
Add two holes to the PCB and the stencil. Then index both with dowel pins. Simple, efficient and cheap.
+1 - the Eurocircuits printer does this and works fine, even with an A4 sized panel and 0.5mm QFPs - no need for X/Y/theta adjustment ( with stainless stencils)
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Online rx8pilot

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Re: New Pick and Place design ideas
« Reply #177 on: May 27, 2016, 06:32:32 pm »
Quote from: Koen on May 27, 2016, 11:44:01 am
Add two holes to the PCB and the stencil. Then index both with dowel pins. Simple, efficient and cheap.

How do you keep blobs of paste from becoming a problem? Put the holes outside of the paste area?
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #178 on: May 28, 2016, 06:47:17 am »
Quote from: rx8pilot on May 27, 2016, 06:32:32 pm
Quote from: Koen on May 27, 2016, 11:44:01 am
Add two holes to the PCB and the stencil. Then index both with dowel pins. Simple, efficient and cheap.

How do you keep blobs of paste from becoming a problem? Put the holes outside of the paste area?
The EC printer uses blocks with 2 pins. The blocks fit the edge of the base using magnets, so you can set the spacing.
One set of pins, short and flat-ended, goes through holes in the bottom edge of the PCB, the other set, with tapered ends, offset to outside the PCB outline, go through the stencil.
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Offline vzoole

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Re: New Pick and Place design ideas
« Reply #179 on: June 01, 2016, 07:34:01 am »
Or check the Eurocircuits stencilfix how it works.

EC stencilfix

« Last Edit: June 01, 2016, 07:55:43 am by vzoole »
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #180 on: June 01, 2016, 08:02:43 am »
Those systems are beautifull but EC is expensive, under 100 euros you get nothing, stencils costs 50+ euro's a piece.
I have used them and for business it is a very good reliable company I can really advise but for hobbieists it is just a too steep entry.

So how do you use this kind of system with any chinese manufacturer?
How do you get the accurate placing holes in the stencil of a cheaper manufacturer?
That is the relevant question I guess. Since the stencils are made out of the pcb gerbers there is no way to place mounting holes outside the pcb area.
You could place a single fictional throughole component outside the pcb, good luck getting that manufactured, all errors go loose in the DRC.
So this solution is single vendor based and not a general applicable solution unless someone can find a solution for this problem.
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Offline l0wside

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Re: New Pick and Place design ideas
« Reply #181 on: June 01, 2016, 11:13:53 am »
I disagree. You can export the Gerber data as usual and then only modify the stencil data, either by a simple script (Perl, Python, ...) or by creating a template for the stencil with holes and using gerbmerge to merge the Gerber data and the stencil template.
The Gerber format is so simple, this should be up and running in a day.

Max
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #182 on: June 01, 2016, 11:18:21 am »
That involves giving the board house two seperate sets of gerbers, hence two seperate orders. The WOW at this moment is that the stencil is generated from the board gerbers.
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Offline l0wside

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Re: New Pick and Place design ideas
« Reply #183 on: June 01, 2016, 11:27:31 am »
So what? The manufacturing for the stencil and the board are two separate processes anyway. Gerber is a set of files, and you simply take out the two files describing the stencil(s), modify them, and add them back to the ZIP file. BTDT.

The stencil data would still be generated by the board gerbers. You simply introduce a post-processing step to change the outline and add the pin holes.

Max
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #184 on: June 01, 2016, 12:28:59 pm »
I see what you mean, you are hinting on the gtp and gbp files, well the three pcb houses I did business with do not use these files, they create the stencil from the combination of the gbl and gbs file and create their own, at least I figure that is how they do it because I never had to sent the gtp and gbp giles and for instance large paste surfaces the stencil gets reinforced with crosses in the middle of the paste surface (or to make sure the paste does not overflow). But if they do use the g*p files your way of working would be a good solution.
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Offline Koen

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Re: New Pick and Place design ideas
« Reply #185 on: June 01, 2016, 12:36:56 pm »
Elecrow and PCBWay have no problem doing it. I add a technical zone to the side of the panelised PCBs and add two holes, nothing more. Simply remind them that both PCB and stencil holes have to align if they modify the Gerbers.
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Offline JuKu

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Re: New Pick and Place design ideas
« Reply #186 on: June 01, 2016, 12:48:25 pm »
This is not that complicated. All CAD programs I have used can generate the stencil dats. And that is the way it should be done, letting the board house generate the stencil data from copper gerbers is a disaster waiting to happen.

You simply place two pads on the stencil data layer in the right places and that's it. You might notify the board house that there are two holes for alignment pins outside the PCB area, but they'll see that anyway, have seen those before and know what they are for.
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #187 on: June 01, 2016, 03:42:30 pm »
I don't understand why anyone thinks this is anything but trivially simple - you just create a component with the tooling hole, and a pad on the paste layer with the correct spacing, and place these at the edge of your panel. Generate gerbers as usual and it will have the required holes.

the only issue I've had is one supplier who cropped the paste layer to the board outline.
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Offline ar__systems

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Re: New Pick and Place design ideas
« Reply #188 on: June 01, 2016, 08:39:57 pm »
Adding holes to your stencil file is indeed trivial. Forget your existing process where you somehow don't provide paste layer to your stencil company. Add the holes to the paste layer and provide it to stencil people. It can be equally simply done in the cad, or merged later directly into the gerber.
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Offline thommo

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Re: New Pick and Place design ideas
« Reply #189 on: June 02, 2016, 02:54:12 am »
Out of interest, what are you guys using to generate your 'panels' in?

For single PCB it's easy, but if you don't have access to panel layout, then things begin to get a bit more difficult.
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Offline D3f1ant

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Re: New Pick and Place design ideas
« Reply #190 on: June 02, 2016, 03:13:23 am »
In Altium you can just place free pads on the 'Paste' layer,  it doesn't affect the drc in any way and I've not had any China or local manufacturer ever question it. To make it simple my PCB template file has all the tooling holes for my quick frame already setup.
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Offline l0wside

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Re: New Pick and Place design ideas
« Reply #191 on: June 02, 2016, 08:35:50 am »
Quote from: Kjelt on June 01, 2016, 12:28:59 pm
the three pcb houses I did business with do not use these files, they create the stencil from the combination of the gbl and gbs file and create their own
Hi Kjelt,

as JuKu pointed out: this is a disaster waiting to happen. There are tons of appnotes explaining how exactly to create a stencil. I doubt that some automagic process at the PCB house would produce better results. Which PCB houses are workign as you described?
My last stencil (and PCBs) were from Elecrow. They had no issue with getting both data separately. For European PCB manufacturers, I suppose the same holds true.

Max
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #192 on: June 02, 2016, 08:36:13 am »
Quote from: thommo on June 02, 2016, 02:54:12 am
Out of interest, what are you guys using to generate your 'panels' in?

For single PCB it's easy, but if you don't have access to panel layout, then things begin to get a bit more difficult.
I always panelise myself (if using subcontractor,ask for their suggested panel size) -too much scope for things to go wrong otherwise.
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Offline Kjelt

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Re: New Pick and Place design ideas
« Reply #193 on: June 02, 2016, 09:47:13 am »
Quote from: l0wside on June 02, 2016, 08:35:50 am
Hi Kjelt,
as JuKu pointed out: this is a disaster waiting to happen. There are tons of appnotes explaining how exactly to create a stencil. I doubt that some automagic process at the PCB house would produce better results. Which PCB houses are workign as you described?
My last stencil (and PCBs) were from Elecrow. They had no issue with getting both data separately. For European PCB manufacturers, I suppose the same holds true.
Max
Seeeedstudio if I am not mistaken.
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Offline thommo

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Re: New Pick and Place design ideas
« Reply #194 on: June 02, 2016, 10:01:36 am »
Mike, what are you using to create your Panelized PCBs in [programme]?

Quote from: mikeselectricstuff on June 02, 2016, 08:36:13 am
Quote from: thommo on June 02, 2016, 02:54:12 am
Out of interest, what are you guys using to generate your 'panels' in?

For single PCB it's easy, but if you don't have access to panel layout, then things begin to get a bit more difficult.
I always panelise myself (if using subcontractor,ask for their suggested panel size) -too much scope for things to go wrong otherwise.
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Offline mikeselectricstuff

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Re: New Pick and Place design ideas
« Reply #195 on: June 02, 2016, 03:38:29 pm »
Quote from: thommo on June 02, 2016, 10:01:36 am
Mike, what are you using to create your Panelized PCBs in [programme]?

Quote from: mikeselectricstuff on June 02, 2016, 08:36:13 am
Quote from: thommo on June 02, 2016, 02:54:12 am
Out of interest, what are you guys using to generate your 'panels' in?

For single PCB it's easy, but if you don't have access to panel layout, then things begin to get a bit more difficult.
I always panelise myself (if using subcontractor,ask for their suggested panel size) -too much scope for things to go wrong otherwise.
I draw the entire panel outline around one circuit within my main  PCB  software (PCAD2006), then step/repeat the circuit gerber/drill data in an external CAM tool (CAMTASTIC)
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Offline mrpackethead

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Re: New Pick and Place design ideas
« Reply #196 on: June 02, 2016, 06:59:06 pm »
I panelise with altium.. its got some tools that make it *eaiser*
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Offline jmelson

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Re: New Pick and Place design ideas
« Reply #197 on: June 28, 2020, 12:15:19 am »
Quote from: rx8pilot on May 26, 2016, 04:10:15 pm
Quote from: Kjelt on May 26, 2016, 07:51:03 am
Quote
I think that $10k buys a person a working and easy-to-use second-hand machine like the Quad's that I have.  Such a machine will be much more capable than anything home-made or designed for hobbyists, largely because all the bugs are worked out.
rx8pilot, can you give an update on the Quad IV C you have?  I need to upgrade my current machine, Philips CSM84, with no vision.  It just isn't accurate for 0.65 and 0.5 mm pitch parts.  Also, the centering jaws seem to only work for parts with about the same 2:1 length-width ratio.  Square chips do not center well.

After looking at tons of machines (I fell in love with the Samsung CP45FV, but out of my price range) I have some people suggesting the PPM-retrofitted Quad IV C with the up-camera (QuadVu 6).  The specs sure LOOK good, but I'm wondering how well it does in the real world?  Also, how reliable are the feeders, how easy is it to program, etc?

I wrote a C program to convert my CAD system's P&P file format to the CSM's form, so I should have no trouble preparing the raw P&P data for it.

Thanks for any info you can provide.  Also, is there a place where I can look at the operator/programming manual?

Jon
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Offline jmelson

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Re: New Pick and Place design ideas
« Reply #198 on: June 28, 2020, 12:37:30 am »
Quote from: rx8pilot on May 10, 2016, 04:37:56 pm

If you make a $10k machine that mis-picks and requires constant supervision and possibly re-work - it will be more expensive than a very reliable $20k machine to even a small business like mine.
So, the biggest problem I have with my $100K (original cost) Philips CSM84 is the peeling of the cover tape.  I constantly have to mess with the feeders where the cover tape won't peel, and ends up covering the part at the pick-up location, or it just causes the feeder to fail to advance.  0.1 uF ceramic caps are the worst offender, I think because the paper tape is just a tiny bit thicker than other tapes.  My usual solution is to put two small C-clamps on the empty tape coming out of the feeder, to give it more "pull".

So, I have to baby-sit the machine while it is running.  Sometimes these issues settle down after a while and it will go through a dozen boards without a feeder jam.  But, the machine is smart enough that it practically never places a part incorrectly, like on its side.

I'd be interested to know how other make's feeders perform in this regard.

Jon
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Offline jmelson

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Re: New Pick and Place design ideas
« Reply #199 on: June 28, 2020, 12:42:22 am »
Quote from: rx8pilot on May 10, 2016, 05:27:45 pm
Not a bad idea to average the feeder error over the course of many picks, is that what you are suggesting? My machine has standard feeders that are good for 0603 and larger.
After making adjustments to the centering jaws on my old school Philips P&P, I put double-sided Scotch tape on a blank board and cut the program for that board down to the fiducials and one part.  I then run that board several times and check the part placement with a microscope.  You can look through the double-sided tape to see alignment between leads and pads.  Then, you can decide whether to adjust the jaws again or adjust the nozzle offset in the software.
I've got my machine dialed in pretty well this way, but with 0.5 and 0.65 mm lead pitch I've pretty much reached the limit of its repeatability.

Jon
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Offline jmelson

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Re: New Pick and Place design ideas
« Reply #200 on: June 28, 2020, 12:48:24 am »
Quote from: bootstrap on May 10, 2016, 07:56:30 pm
About the case of "black component on black tape" (or "white component on white tape").  How do seriously professional feeders that can absolutely, positively move the tape EXACTLY the appropriate distance every time... make sure they can pick up the FIRST of those components after the reel is loaded (to get in sync)?
Well, the feeders on my Philips (made by Yamaha) machine require about 8 mm of tape ahead of the pick-up point to reach the sprocket.  So, you have to spill 3 0805-size parts, or 2 small ICs.  You can put those in a box for later rework, or put them back in the tape later.  This is really not a big problem when you are working with cut tapes of expensive chips, and I never sweat over the couple resistors and caps here and there.

Jon
« Last Edit: June 28, 2020, 01:20:26 am by jmelson »
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Offline jmelson

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