Author Topic: Bringing PCB assembly in-house with Dima Optimat?  (Read 7304 times)

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Offline Styno

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Bringing PCB assembly in-house with Dima Optimat?
« on: November 09, 2018, 09:32:42 pm »
Since I found this forum most helpful, I registered to ask some questions as well as try to contribute something in return. So here’s the story which may sound familiar to many of you:
I work for a small software company which core business is providing networking access and monitoring/control of remote industrial installation, from few tens to many tens of thousands I/O. Despite being primarily a software/system integration company, we always deploy some local data processing using a combination of off the shelf low power ARM platforms (nowadays called fog computing in marketing terms) and custom interfacing pcb’s. Assembly of these has always been outsourced. But with the rise of (sorry, another buzzword) IoT the volume and diversity of in-house designed electronics has sharply gone up. Plenty of meetings with management later and it is decided we in-house the pcb-assembly.

There are many reasons, money far from being the #1:
Contract assembly can be a bitch and take a lot of time and effort documenting. Especially with some of the weird glue-logic constructions we come up with  :-// Also, the turn-around time is often long (8 weeks+) because we do small batches: 200 pcs is considered a large order for us but not for them. Being able to produce a single/few panel when needed without too much hassle is a huge benefit. For over 20 years we’ve used an Essemtec manual pick and place together with an Essemtec IR batch reflow oven for prototyping and small production runs. But volume is starting to go up sharply and working on the manual PnP all day, days on end is no fun.

So, based on the experience/advise from members of this forum we decided to dip our toes in and shop around for an second hand PnP instead of a new cheap Chinese, stencil printer and convection reflow oven. A local broker advised:
- In-line half-automatic stencil printer. Mainly for repeatabilty and the option of using a less skilled operator. And because half-automatic is not that more expensive then guided-manual.

- In-line Dima Optimat SMPM-2000 PnP machine. This machine from 2002 has top and bottom vision and room for ~105 8/12mm feeders. It should be able to place 0402 and 0.5 pitch components. Dima’s are said to be good for high mix, low volume and therefore easy to setup (e.g. Teach-in function). It’s mechanics are simple and robust. The vision system and other components are widely used and still available. The UI is DOS based (under WinXP) and easy to use, e.g. Local language (Dutch) is selectable. The feeders are mechanical and dirt cheap (€30 on Ebay) so I plan to get as much feeders as possible and have the components for the most designs permanently on the machine. A review of 6 pcb designs learns that ~70% of the components uses 8mm tape and that about 60 slots are needed, so there is still a little room left for more designs.
According to the broker this particular machine has seen few running hours.

- In-line 5-zone wire-mesh conveyor full convection oven (4 heating, 1 cooling? Not sure about that).

I expect the quote to come in at about EUR 25k.

We are aware that the PnP is dead slow with a gross rate of 2000 cph however approximately 1 or 2 panels per hour is much faster than manual work anyway. This is enough for us for the moment. I reckon that, when we we are lucky enough to need more capacity or improved handling, the experience with this ‘cheap’ setup will have paid for itself and tought us a lot. Plenty of space in the workshop, so size is not a problem.

Any of you have experience/tips for this particular PnP? What are it’s weak points besides being slow, what should I ask the broker or check before buying? When the deal goes through I hope to be able to share the experience as well.

Edit:
Dima Optimat SMPM-2000 datasheet.pdf
« Last Edit: November 15, 2018, 10:45:48 am by Styno »
 

Offline SMTech

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Re: Bringing PCB assembly in-house with Dima Optimat
« Reply #1 on: November 09, 2018, 10:14:47 pm »
I looked very closely at Dima (New) before going Essemtec, and they seemed a good match for what you are describing, however I  was looking at the HP-100 & MP-200 machines. At that time I did notice several older Dima models like the Optimat come on the market and they were always very cheap and that was 7 years ago. The feeders were quite a nice compact design that seemed to be used on their newer platforms.
 25k all in for a line isn't terrible and Dima being a local company to you probably means you have better access to help and parts than people elsewhere, when I was looking my biggest concerns in the UK were the very low installed base in the UK and the fact Dima themselves were very dispensing obsessed - it was all they promoted at events etc. Behold today Dima is gone, slurped up into Nordson, who have kept.. dispensing.

Personally however I would go with a used machine where there is more support and maybe even a use for your feeders when you decide the machine needs to be quicker, something like a MyData or Europlacer (who make machines for YOU) or one of the Yamaha made machines.

Seeing as I run one I can also recommend the newer Essemtecs for the work you describe, there's a Paraquda listed on adoptsmt right now....

Printer, semi-automatic can mean so many things, personally I would either go inline fully automatic (built like tanks lots of them out there, hopefully with extras like SPI), or offline and choose something like the Reprint Miniko. None of this mylar film rubbish.

A 4 zone oven will probably do you fine for most things, more zones gives you more control if you are targeting a very specific profile and helps get heat into big awkward parts, more length gives you more throughput. If you know now you use big heavy parts or big heavy/ceramic boards, maybe you might want something beefier. Also worth considering are small Vapor phase ovens, these take up very little space & have excellent heat transfer., the downsides are they can emphasise poor stencil/footprint with a higher risk of tombstoning, and they are not Electrolytics best friend.

As a subcontractor we run jobs in exactly the sizes you describe, the only time we would normally quote a lead time in the 8 week region would involve metalwork or sourcing issues. Bigger places do bigger jobs that require more planning, some have lots of knowledgeable people others have just one or two and a room full of monkeys, that can mean the wait is actually for the overworked non-monkey to set your job up.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat
« Reply #2 on: November 10, 2018, 08:05:42 am »
I'm about 3 years down the road from the place you are today.  THe best thing i ever did was stop relying on CM, and brought it in house.   I've gone Yamaha ( now have 2 Yv-100iis) and will be adding a third slightly newer machine..    I've also had chinese desktops and i'd just say avoid them, it will just result in pain.      I'm using Vapour Phase and its great.   I dont' have too much problem with electrolytics,  ( we dont' use lots though ).. Tombstones are a matter of good solder paste application..  dont' underestimate solder paste application.. that is where 90%+ of your issues will start.
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat
« Reply #3 on: November 10, 2018, 08:30:30 am »
I looked very closely at Dima (New) before going Essemtec, and they seemed a good match for what you are describing, however I  was looking at the HP-100 & MP-200 machines. At that time I did notice several older Dima models like the Optimat come on the market and they were always very cheap and that was 7 years ago.
First: thanks for your thoughts! The local broker also has an MP-200 machine available and initially I had my eye on it as it's more capable on all accounts but he did not recommend it for us because it's more complex and needs more maintenance. E.g. he said the servos need periodic calibration that can only be done by a trained technician.
Quote
The feeders were quite a nice compact design that seemed to be used on their newer platforms.
As I understand, the newer machines use intelligent feeders where the Optimat uses head activated pure mechanical ones. The intelligent feeders are an order of magnitude more expensive and, since we will try to keep our components on the machine at all times, the intelligence does not add much value for us.
 
Quote
25k all in for a line isn't terrible and Dima being a local company to you probably means you have better access to help and parts than people elsewhere, when I was looking my biggest concerns in the UK were the very low installed base in the UK and the fact Dima themselves were very dispensing obsessed - it was all they promoted at events etc. Behold today Dima is gone, slurped up into Nordson, who have kept.. dispensing.

Personally however I would go with a used machine where there is more support and maybe even a use for your feeders when you decide the machine needs to be quicker, something like a MyData or Europlacer (who make machines for YOU) or one of the Yamaha made machines.
I'm not entirely sure but i have the feeling there is still expertise around for the Dima machines, but this may be specifically a Dutch situation. I'll ask about this next week.
60x 8mm feeders is about $1800 @ Ebay prices. So, not being able to reuse them on a possible future machine is not a big loss. The vibration and tray feeder are a bit more expensive though at ~$600 each...

Quote
Seeing as I run one I can also recommend the newer Essemtecs for the work you describe, there's a Paraquda listed on adoptsmt right now....
Yeah, I drool over such a machine but, alas, I reckon this one will come in over twice our current investment for the PnP alone? Especially with a bunch of feeders included. Pretty sure that won't pass upstairs at this stage. Sure, when assembly is your core business the situation would be quite different.

Quote
Printer, semi-automatic can mean so many things, personally I would either go inline fully automatic (built like tanks lots of them out there, hopefully with extras like SPI), or offline and choose something like the Reprint Miniko. None of this mylar film rubbish.
We use stainless steel stencils. The printer in question is appropriately named  :)  SMTech AVP300. Not sure what 'SPI' means but it has fiducial recognition.

Quote
A 4 zone oven will probably do you fine for most things, more zones gives you more control if you are targeting a very specific profile and helps get heat into big awkward parts more length gives you more throughput. If you know now you use big heavy parts or big heavy/ceramic boards, maybe you might want something beefier.
We build primarily small compact low power stuff, the biggest items being thin RF modules (2 by 3 cm max) and Ethernet jacks. I hope it's a significant step up from our IR batch oven which heats panels not entirely even and cannot follow lead-free reflow curves quickly enough. I guess anything has higher throughput than the PnP. I'm even considering stacking the assembled boards and than bake them at the end of the day, avoiding keeping the oven on but idling most of the day. But not sure if that is worth the effort vs kWh's saved.

Quote
Also worth considering are small Vapor phase ovens, these take up very little space & have excellent heat transfer., the downsides are they can emphasise poor stencil/footprint with a higher risk of tombstoning, and they are not Electrolytics best friend.
The broker had a few IBL batch VP ovens on hand but did not recommend them, primarily because we apparently do not really need that and the significant price hike over an inline convection oven.

Quote
As a subcontractor we run jobs in exactly the sizes you describe, the only time we would normally quote a lead time in the 8 week region would involve metalwork or sourcing issues. Bigger places do bigger jobs that require more planning, some have lots of knowledgeable people others have just one or two and a room full of monkeys, that can mean the wait is actually for the overworked non-monkey to set your job up.
Thanks for that insight. Yes, our current contractor is quite large and recommended to us by another company that does much larger volume simply because that is their core-business. I'll reconsider other contractors as well.

Thanks again for your input. I hope my reaction makes sense as apart from manual assembly this area is quite new to me.
« Last Edit: November 10, 2018, 08:33:14 am by Styno »
 

Offline SMTech

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #4 on: November 11, 2018, 11:10:18 am »
From what I understand the AVP300 to be, seems like a good choice to me, and I think they still supported/refurbished by Reprint, who possibly made it (there is a link of some kind).

Mylar is technique used by many semi-automatic printers, basically you put the PCB in its fixture, put a mylar screen over it and print. Typically there is an area outside the print area, so you slide the fixuture out, now you finely tune your alignment of your mylar print onto the PCB either by eye or with the assistance of cameras. Once your happy, remove the mylar and print away. A PLC controller handles the squeegee speeds pressures etc.

SPI is solder paste inspection, or AOI for your printing, some automatic printer have a camera fitted that can do this at some level.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #5 on: November 13, 2018, 08:38:00 am »
We won't run this line full stop or even every day, certainly not the first year. So I was wondering:
- do you have to clean such an (semi) automatic printer after each use? I guess the simple answer is yes.
- so how do you clean the machine? Lots of alcohol and paper towel? There are two wiper blades closely spaced, it seems a lot of dirty work to get that clean...

Currently, after manual printing we wipe the stencil clean on a flat table using paper towel with alcohol or petrol, then lift the stencil to clean the residue off the table and repeating this process until it's judged to be 'clean enough'.

Any tips?
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #6 on: November 13, 2018, 09:19:06 am »
I wash our stainless steel stencils with a PCB board wash solution, which does a really nice job of it.     ( the solvents in teh paste is not Alcohol soluable  ( henkel GC10 )..  i give them a first scrub down, with that and hot water, and then they get put in a ultrasonic bath for 10 minutes, to get the last little bits out.    They then get air dryed..  I'd do that after the days effort is done,     Your stencil printer may have a clean stroke as well.

If you are making lots of the same product, its well worth getting two stencils, ( or even three ).  If you damage one ( it does happen ), and you can have one being cleaned while one is on the machine.   These days with stencils being only $40-50 is not overaly expensive
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Offline Gary.M

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #7 on: November 13, 2018, 09:55:01 pm »
Sodium percarbonate in hottish water will clean your stencils super clean, no ultrasonic needed. Very cheap too.
 

Offline SMTech

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #8 on: November 14, 2018, 12:17:15 am »
You should only need to clean the stencil and the blades, the blade assembly normally comes out very easily for that purpose. If you've managed to get paste anywhere else I think something would have gone wrong.
I clean my stencils using a similar procedure to you, good lint free towels and stencil cleaner formulated by our paste manufacturer BLT, it is IPA based with some extra secret sauce.

 In the past we have used some generic stencil cleaner from Farnell and label remover (the stuff that smells a bit like oranges) is also surprisingly good at it. This isn't perfect, it is quite hard to flush everything out of apertures, proper stencil cleaning machines are expensive beasts (not least because commercial stencils are huge). I have other toys on my shopping list I would choose first given the budget. An improvement on this process would be a handheld ultrasonic like this http://www.gen3systems.com/gensonic-stencil-cleaner one of those is probably IRO £1500 but I keep meaning to have a go at building one using a £40 ebay transducer&driver
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #9 on: November 14, 2018, 04:11:09 am »
http://www.chemtools.com.au/product/electrical-electronics/electronics-cleaning-chemicals/pcb-flux-remover/


^^ This is what i use. I'm not entirely sure what it is.. 20L drum cost sabout NZ$120...     
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #10 on: November 14, 2018, 08:08:33 am »
Thanks all for these great tips!

I've got a quote for an alternative to the convection oven: and IBL VPP-M 400 vapour phase batch reflow oven. It's a bit over €5k and about ~€1k more than the convection. But a) we don't need a fully inline oven, b) de VPP should be quite a bit less smelly and hot and more energy efficient as well as use less space, c) I'm attracted to the potentially better solder joint quality. So we'll see if that can be squeezed into the budget.

Another question:
How do you teach a new pcb on the PnP? Do you add paste and just try, manually correcting afterwards? I see that many of those Chinese promotion youtube video's use double sided sticky tape or perhaps spray glue. Since this oldie doesn't project a virtual component over the pcb image I assume I will need multiple test runs before the angles and offsets in the PnP library fit the CAD libraries.
« Last Edit: November 14, 2018, 08:13:37 am by Styno »
 

Offline olkipukki

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #11 on: November 14, 2018, 08:43:27 pm »
re: stencil cleaning
I am using stencil wipes https://www.electrolube.com/products/cleaning/ssw/wipes/  :-+
 

Offline mikeselectricstuff

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #12 on: November 15, 2018, 07:03:31 am »
For test placements,use low tack double-sided thin-film adhesive tape.you need the stuff that's fairly translucent so you can see the pads.
Apply with minimum pressure so it comes off easily-just lay it on.
May need to find a few types to get one that comes off cleanly.
Remember you usually won't need to cover the whole board, just a few places for one of each part. I find 25mm is a good compromise between coverage and ease of removal
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Offline Ice-Tea

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #13 on: November 15, 2018, 07:11:40 am »
My 0.05$: having to provide lots of documentation for a contractor is not a valid reason to go inhouse. The documentation should roll out easily out of whatever version control/managment system/CAD implemenation you have. If that is not the case, my guess is going "documentation-light" is going to bite you in the ass sooner or later.

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #14 on: November 15, 2018, 07:17:44 am »
My 0.05$: having to provide lots of documentation for a contractor is not a valid reason to go inhouse. The documentation should roll out easily out of whatever version control/managment system/CAD implemenation you have. If that is not the case, my guess is going "documentation-light" is going to bite you in the ass sooner or later.

I say it is a good reason.   I have invested substaintial effort in our system, so that everythign is consistent end to end.   Contractors don't know your systems, and you dont' know theres.      Its not about 'not' having the info, its about understanding it.    And you never quite know when the 'understanding-light' is going to bite you in the proverbial;
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Offline mikeselectricstuff

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #15 on: November 15, 2018, 08:26:17 am »
My 0.05$: having to provide lots of documentation for a contractor is not a valid reason to go inhouse. The documentation should roll out easily out of whatever version control/managment system/CAD implemenation you have. If that is not the case, my guess is going "documentation-light" is going to bite you in the ass sooner or later.
Depends on the nature of the business. For me it is very rare that I need to build a second batch of a job, so time spent documenting would be way more than time figuring things out on the rare occasion I need to re-run a job.
Chances are you'll need to sub some parts due to availabilty, maybe make other changes, so it still takes time regardless of how well documented it was originally. My pick&place has easily paid for itself from time saved dealing with subcontractors alone.
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #16 on: November 15, 2018, 08:44:59 am »
Again, all thanks for your valuable thoughts.

I'd like to reply to this:
My 0.05$: having to provide lots of documentation for a contractor is not a valid reason to go inhouse. The documentation should roll out easily out of whatever version control/managment system/CAD implemenation you have. If that is not the case, my guess is going "documentation-light" is going to bite you in the ass sooner or later.
In my first post I tried to explain that there are several reasons to go in-house, communication problems just being one of them. I hope there is no confusion about this.

But anyway, I'll give an example: I've developed a 2-layer interface board to fit a certain small round housing. In my CAD board drawing I only made the outline round, the two copper layers are drawn as a square around the board. The CAD renderer and every online and offline Gerber viewer I tried shows the board correctly with the copper reduced to the outline of the board with some pull-back. Using the iterate often and quick method I have several versions of the board made through three board manufacturers in China. All came back perfectly as I intended, no questions asked.
So all is well and, finally, it's time for a series production run. I send the same Gerbers with assembly instructions and pictures of the half- and final assembly to a big contractor in the Netherlands. The first response I get back is: your copper pour is square but your board is round, we can't make this.  :-//

I don't want to spend time on that sort of communication.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #17 on: November 15, 2018, 09:03:47 am »
Depends on the nature of the business. For me it is very rare that I need to build a second batch of a job, so time spent documenting would be way more than time figuring things out on the rare occasion I need to re-run a job.
Chances are you'll need to sub some parts due to availabilty, maybe make other changes, so it still takes time regardless of how well documented it was originally.
Partially, this is how our business works as well. There are some (nearly) one-off projects, however there will also be some products that get sold for many years (10+ years) in quantities of a few hundred to a few thousand a year.

Quote
My pick&place has easily paid for itself from time saved dealing with subcontractors alone.
I've got one order in the pipeline for about 200 boards that will pay for the hardware already, after that we hope to enjoy to produce many more orders on the same machines. So, the hardware purchase isn't the problem.

The unknown is: can we get producing quickly after we receive the machines (i.e. 1 to 2 weeks)? The boards aren't that demanding regarding passives size or chip pitch so that will help. The machines are serviced and delivered in working condition before delivery, so that helps too. The broker will also provide a one day training and phone support if we run into issues. Finally the broker has visited us and we talked for quite a while. He told us: the Dima is so simple, and because we already have experience in manual PCB production (i.e. check for correct orientation of diodes and basic stuff like that), and our workshop doesn't need much preparation, that he expects us to easily be able to get boards populated in that timeframe.

I don't have the experience yet to judge if he's correct but we'll see. I've been told that next week the green or red light will be given from management.

Edit:
The broker also told me he expects us to use the PnP for prototypes as well with a little bit of CAD export scripting. Also because the PnP is so simple. Again, we'll see if he's correct. I've asked him if he could provide me a contact who actively uses the same machine so I can get a users perspective.
« Last Edit: November 15, 2018, 09:19:28 am by Styno »
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #18 on: November 15, 2018, 09:24:19 am »
I would suggest 1-2 weeks is very very optimistic.
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #19 on: November 15, 2018, 09:51:53 am »
Yes, rightly so I guess. I'm sceptical as well but that's purely based on the experiences from this forum. From you, rx8pilot, Mikeselectricstuff and others.

While rx8pilot's story sounds like a horror movie for a commercial company that has work to get done instead of fixing broken PnP's, the machine we'll get is in good working order and has few running hours. E.g. the feeders that were on the machine looked like brand new.

There's likely a difference between the time getting the first board populated vs being able to produce boards without too much operational problems and manual correction afterwards. I hope to be able to comment on that later  :)
 

Offline Ice-Tea

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #20 on: November 15, 2018, 09:57:40 am »
But anyway, I'll give an example: I've developed a 2-layer interface board to fit a certain small round housing. In my CAD board drawing I only made the outline round, the two copper layers are drawn as a square around the board. The CAD renderer and every online and offline Gerber viewer I tried shows the board correctly with the copper reduced to the outline of the board with some pull-back. Using the iterate often and quick method I have several versions of the board made through three board manufacturers in China. All came back perfectly as I intended, no questions asked.
So all is well and, finally, it's time for a series production run. I send the same Gerbers with assembly instructions and pictures of the half- and final assembly to a big contractor in the Netherlands. The first response I get back is: your copper pour is square but your board is round, we can't make this.  :-//

I don't want to spend time on that sort of communication.

I'm having trouble picturing what those Gerbers would have looked like but in general: I prefer a supplier that asks questions over one that guesses what my intentions could have been. In this case it may have been an annoyance, in other cases it could have saved your bacon.

I'll add an example: I once had an error in an outjob file, did a quick revision on holliday while people were litteraly waiting on me at the door to finish up. The 4 layer board left with top and bottom gerbers and 2 blank inner layers. They produced it like that, shorted everything out. I would have prefered someone asking me a question at that point instead of loosing a wad of cash, the assignment and face.

But I understand that your scenario may be different.

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #21 on: November 15, 2018, 10:41:06 am »
It has me wondering what is in the Gerbers as well but, really, I'm not going to investigate. Why should I? The point is: at least 5 different online and offline Gerber viewers show the board correctly as I intended, none had problems with my data and three different board manufactures make the board as intended. So why should I question my design or wonder whether the Gerber data is right or wrong?

But 'your Gerbers are wrong!' is the first response I get when trying to outsource assembly... They may very well be 'technically' correct, but I gave them enough information (photo's, assembly description) to work it out themselves. Not meaning to offense anyone but I already have an autistic colleague, I don't pay for a contractor to be one too!

Edit:
Re stencil cleaning: Only just found out that simply washing the stainless steel stencil with running tap water cleans it perfectly. :palm:
« Last Edit: November 15, 2018, 11:07:45 am by Styno »
 

Offline mikeselectricstuff

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #22 on: November 15, 2018, 11:56:09 am »
I would suggest 1-2 weeks is very very optimistic.
For a known-working machine with dealer support it's probably quite doable if you don't have much else to do
Just make sure you have PLENTY  of spare parts and PCBs, and make more than you need to deliver soon
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Offline SMTech

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #23 on: November 15, 2018, 12:10:52 pm »
Well I will beg to differ on the questions front, questions are good, it means they are paying attention Just because a handful of free tools that are probably all powered by exactly the same set of open source libraries APPEAR to render your files as you seem to want them doesn't mean they aren't in someway invalid or will fail some facilities automated DFM checks. What you should do with feedback like that is work out why the way you are doing it is wrong and fix it. The only clients I we deal with who are pretty much always right, are the ones with systems and procedures in place who do things properly or who work on very high end stuff and have made the effort to understand how manufacturing works, the other guys break all sorts of design rules, have shoddy BOMs, shoddy procedures, and expect everyone around them to be psychic. I know which kind of shop you should be trying to be, amd you will certainly find out the hard way if you bring it in house and don't gear yourself that way.

However, bearing in mind we already knew how to print & reflow, our experience of receiving new machines with on-site training. Machine Deliver+commission+24hours to get to room temp = day one. Day 2 = Training using our data & products and actual product being created. As long as the person being trained on the machine has some concept already as to what is going on and your broker can provide such training I don't see why you should be able to do the same. Get advance details of exactly what data this machine likes to be fed, buy your stencils, frame adaptors if required, components for a few products, have your datasheets and dimensions to hand for all those parts, and a set of calipers for where that data is wrong or missing.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #24 on: November 15, 2018, 04:27:59 pm »
@SMTech, thanks for that sobering response. I had not considered the possibility of all those (cheap) manufacturers plus a bunch of opensource/free Gerber viewers using the same open source libraries. I must also accept that they (the assembly house) are way more experienced and professional than I, a physics degree that wondered by chance and interest into EE several years ago. So, yeah, it's probably my fault.

Doesn't change the fact that I hate that my lowly perfection level worked well before and now someone else determined that there is a problem with that design though.

Edit:
@Mike, I'll be looking around for thin, transparent and low-tack double sided tape. And already have several reels available for initial testing and learning. Thanks for those tips.
« Last Edit: November 15, 2018, 04:32:56 pm by Styno »
 

Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat
« Reply #25 on: November 15, 2018, 08:48:59 pm »
I'm about 3 years down the road from the place you are today.  THe best thing i ever did was stop relying on CM, and brought it in house.   I've gone Yamaha ( now have 2 Yv-100iis) and will be adding a third slightly newer machine..    I've also had chinese desktops and i'd just say avoid them, it will just result in pain.      I'm using Vapour Phase and its great.   I dont' have too much problem with electrolytics,  ( we dont' use lots though ).. Tombstones are a matter of good solder paste application..  dont' underestimate solder paste application.. that is where 90%+ of your issues will start.
I did this 11 years ago.  I bought a used Philips CSM84 (made by Yamaha).  It has 3 nozzles, so can mount different size nozzles for different size range of parts.  Although vision is an available option on this model, my machine did not have it.  I never used CM's, I did it all by hand before.  I made my first board within 2 weeks of getting the machine in.  I hacked a big toaster oven with a ramp-and-soak thermocouple controller to do the reflow profile.

I have done close to 2000 boards on this system, now, and have had, maybe TWO real tombstones!  I have had a few "head in pillow" defects where the paste never joined to the component.  But, that is also fairly rare.

I do not teach the assembly, I get the placement file out of my CAD system and convert it to the machine's native file format with a program I wrote in C.  I only teach non-standard pick-up locations, like from a waffle tray.

I do look at these Chinese machines, and the open PnP project, but it seems they just are not up to the capabilities of the commercial machines (yet).  My very old (1995-vintage) Philips has excellent recovery from a wide range of errors, and tries to keep on going even when things are going wrong.  I have only had to wipe the parts and paste off a few (less than 4) boards out of those nearly 2000 boards when things went seriously wrong.

Jon
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #26 on: November 15, 2018, 10:15:39 pm »
I would suggest 1-2 weeks is very very optimistic.
For a known-working machine with dealer support it's probably quite doable if you don't have much else to do
Just make sure you have PLENTY  of spare parts and PCBs, and make more than you need to deliver soon

yes, maybe my expereince was tainted by buying some machines at Auction, with NO manuals,  and having to do it by just trying and learning!     Having someone to show you would dramatically improve things.
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Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #27 on: November 16, 2018, 08:23:56 pm »

yes, maybe my expereince was tainted by buying some machines at Auction, with NO manuals,  and having to do it by just trying and learning!     Having someone to show you would dramatically improve things.
OHHH!  No, that would be HORRIBLE with the complexity of these machines and software.  I got some manuals with my machine, and later the previous owner found a bunch more manuals of different vintage.  I now have 3 different generations of manuals for my generic machine, and the quality is QUITE different.  Obviously, the first one is a pretty literal translation from the Japanese manual, the second is a modest clean-up, and the 3rd one is a total rewrite done by a native English speaker who was deeply experienced in the P&P world.  WOW, what a difference experience in both the language and the subject matter can make!

I would have NEVER gotten as conversant with the machine and especially the software without these manuals.  I still have run into really cryptic stuff, and even error messages that are NOT anywhere in the manuals, so I had to guess what the cause was.  But, nevertheless, the manuals made a steep learning curve possible.

Jon
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #28 on: November 17, 2018, 09:27:12 pm »
Just for clarification, i had the 'user-manual' but not the programming manual for VIOS..  The Vios files are SPACE delimited, and its absolutely critical that everthign is perfect, or you get really weird errors!
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #29 on: November 17, 2018, 10:57:38 pm »
I’ve received two board configuration files for the dima. One for a single board and one for a panel. Being text files, they look pretty self explanatory and mostly comma separated.

Exporting one board from CAD and then use the machine UI to convert it into a panel should be pretty easy as well. Looking good so far.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #30 on: November 17, 2018, 11:32:55 pm »
Attached is a VIOS config file.
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #31 on: November 18, 2018, 05:50:58 am »
Thanks, the ViOS format is way less readable and more complex than Dima’s. I’ll post one as well later.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #32 on: November 18, 2018, 06:03:18 am »
The clever people will note that the vios file i provided does not carry all the specific data for each component ( which you could do ).   When i import the the file, i then do a 'match to component database' which then uses the parameters from teh database, rather than my own specific stuff.  Otherwise its just a bit hard.
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #33 on: November 20, 2018, 07:39:46 pm »
Update. To use a fitting Dutch proverb: the bullet is through the church! Yep, that probably does not make a lot of sense to most of you but it means that the decision has been made to make the investment and upgrade to the IBL vapour phase oven. Can’t wait for the machines to arrive  :D
 

Offline RobK_NL

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #34 on: November 20, 2018, 09:01:04 pm »
"The die is cast"
Tell us what problem you want to solve, not what solution you're having problems with
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #35 on: November 21, 2018, 06:17:56 pm »
At the last moment we received an offer to upgrade the VP oven to a much newer Asscon Quicky VP450 and management agreed.
Reasons to upgrade:
-much newer
-smaller footprint
-needs about 5kg Galden to work instead of 15kg.
-Galden-wise much more efficient (less loss per cycle)
-closed-loop cooling
-looks much better (yes that is somehow important  :palm: )

The hardware gets delivered in about two to three weeks so it’s time to cleanup shop and make sure enough electrical circuits are available. I guess the oven, compressor and PnP/stencil machine all need separate circuits.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #36 on: November 27, 2018, 08:57:18 am »
We will need additional adapters for large reels (e.g. 330mm), anyone knows what those would cost approximately?
 

Offline RobK_NL

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #37 on: November 27, 2018, 09:35:17 am »
Styno,

Those adapters (p/n SMPM-5051) should cost less than a feeder, I think. It's only a steel plate with a bolt through it.

Peter-Paul should be able to tell you. There is also a company called TwenTech that seems to sell them.
Tell us what problem you want to solve, not what solution you're having problems with
 
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Offline mike_58

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #38 on: December 07, 2018, 05:27:05 am »
Hi,

I came across this Guy- I would recommend this Co. from China if you ever need spare parts - they have a large old stock and plenty of used feeders for quite a good price:
Jacky Gao (Sales Manager)
sales@jmsaohar.cn
Shenzhen JM Saohar technology Co.,Ltd
Motink Technology Limited
http://www.smt2000.com/
Cellphone/Wechat: +86-18503055169
QQ: 55016787            Skype: tinkeijacky

Good luck!
Mike
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #39 on: December 20, 2018, 07:57:50 pm »
Today the machines were delivered and we spent a good deal of the day setting them up. Unfortunately some issues popped up.

Stencil printer is missing one of the two pcb transport belts. These are very thin so is easily overlooked I guess.
The PnP was probably setup while not level before transport so when we set it up level in the shop the pcb transport rails were slightly twisted which locked the axels. We noticed this only when we tried to load a pcb, it burned out the pcb belt drive motor.
Obviously the feeders are secondhand where some look brand new still while others have broken/incomplete spools, some have missing parts too.

So, I feel a bit ‘meh’ right now. Especialy the missing belt and broken/incomplete feeders make me feel that the delivery preparation was a bit sloppy. The supplier will be back in a few days with a new motor and fixed feeders. Hopefully, by then, we can get to acquint ourselves with the machines.

PS. Galden LS230 vapor stinks! I had not realised this, but even the tiny bit that escapes when you open the lid smells overwhelmingly nasty  :--
« Last Edit: December 20, 2018, 08:00:22 pm by Styno »
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #40 on: December 21, 2018, 08:06:13 am »
PS. Galden LS230 vapor stinks! I had not realised this, but even the tiny bit that escapes when you open the lid smells overwhelmingly nasty  :--

Is your machine clean, or is there lots of flux residue lying around inside it.    My machines dont' smell badly when clean and new galden. I'm sure its related to the flux.

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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #41 on: December 21, 2018, 12:28:25 pm »
Thanks for that. I really don't know if or what is wrong at this stage as I haven't read the manual yet, but I'm told there is a paper filter (like a really big coffee filter) for removing the flux.

The supplier assured me that there was enough fluid present but I have my doubts as the heating element at one point raises slightly above the Galden. But the machine is apparently content with the level.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #42 on: December 21, 2018, 12:41:48 pm »
i filter my galden with coffee filters, and a funnel,  it gets rid of most of the crud.

I'm not familar with your machine, but with mine, i litterally only have about 5mm of galden in the bottom of the tank.   A little bit makes a LOT of vapour.

Something to keep it mind, it appears to be quite hydroscopic, and on teh first heat cycle it can create 'clouds'. Dont' be tricked into thinking that its galden, it often is just steam.



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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #43 on: December 21, 2018, 06:12:40 pm »
I'll ask the seller if the Galden is newly added, if the VP machine has been cleaned and/or if the filter has been replaced. Thanks.

Today, I played a bit with the P&P and the feeders. The feeders have really simple mechanics and it took less than 5 minutes to figure out how they operate and then to load the first reel. It seems we will be able to run through our stock of cut-tape first without losing any components using only an SMT cover tape leader like this.
 

Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #44 on: December 21, 2018, 08:15:05 pm »
I'll ask the seller if the Galden is newly added, if the VP machine has been cleaned and/or if the filter has been replaced. Thanks.

Today, I played a bit with the P&P and the feeders. The feeders have really simple mechanics and it took less than 5 minutes to figure out how they operate and then to load the first reel. It seems we will be able to run through our stock of cut-tape first without losing any components using only an SMT cover tape leader like this.
I just splice the cover tape with masking tape, works very well.  I have yards of old cover tape laying around.  I don't worry over losing 2 SMT resistors when starting with cut tape.  Resistors and caps are so cheap, I generally buy a whole reel of almost anything passive.  For the ICs, I can take out two at the beginning of the tape, and then put them back in near the end so I can use all parts.  I almost always buy a few extra so I can do repairs and to cover for parts dropped by the machine (relatively rare, but it happens once in a while.)

Jon
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #45 on: December 21, 2018, 09:05:44 pm »
I realised too late that spent cover tape could be useful for use in the feeders so I didn’t instruct my collueges to save some. Fortunately those extenders are pretty cheap.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #46 on: January 01, 2019, 05:55:49 pm »
According to the manual I need some tools to calibrate the p&p machine, most notably an aluminium plate covered with (double cross) fiducials that needs to be placed on the pcb conveyor and some smaller plates with one fiducial or small text that need to be mounted on the nozzle. The big plate is for getting info on x/y inaccuracies while the smaller are for calibrating the component camera.

Unfortunately these did not come with the machine. Does anyone have these or photo’s/drawings of them? I’m also interested in the service manual.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #47 on: January 01, 2019, 07:47:37 pm »
According to the manual I need some tools to calibrate the p&p machine, most notably an aluminium plate covered with (double cross) fiducials that needs to be placed on the pcb conveyor and some smaller plates with one fiducial or small text that need to be mounted on the nozzle. The big plate is for getting info on x/y inaccuracies while the smaller are for calibrating the component camera.

Unfortunately these did not come with the machine. Does anyone have these or photo’s/drawings of them? I’m also interested in the service manual.

The yamaha machines, use a special pcb for this task, but i could not get one, so i had one made. ( single sided  ).   You might need to do something similar?  Its probably cheaper and easier than using an aluminu plate>
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #48 on: January 02, 2019, 08:36:42 am »
Creating a pcb was indeed on my mind but I'm guessing the machine has some hardcoded(?) info on the amount and spacing of the fiducials it expects on that pcb/plate?

From the Calibration Manual Ver 2.50 Chapter 2.3.6:
Quote
Now that the main machine deficiencies are known, the next step is to make a map of the machine co-ordinates. By measuring each spot in the work area, a table can be build in which all machine co-ordinates are related to a physical spot in the work area. In this way the Optimat software van compensate for (mechanical) flaws and inacuracies in the positioning system. To accomodate this, you should used the aluminium calibration plate which is covered with fiducials.

If this option is selected the user is requested to place the correction plate (see Appendix B) on the run-in side of the transport. The plate will be transported into the work area. The user first has to position the crosshair over the bottom left fiducial and over the bottom right fiducial of the correction plate. These two measurements determine the angle under which the plate is loaded. Now the crosses on the plate will be measured. This will take approximately a half hour. The measurement can be stopped by pressing the ESC key.

Finally, the user is asked whether the new correction data must be stored (in  the file Correct.dat). Previous correction data will be renamed to Cor_old.dat.
 

Offline SMTech

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #49 on: January 02, 2019, 09:12:38 am »
It would indeed almost certainly be hardcoded grid of fiducials it was expecting, I would expect most people who had an Optimat to not own a calibration plate. Instead that would be something Dima/their local service representative would have and would use as part of every regular service. Companies that have lots of machines and do more of the mechanical support themselves might go so far as to have one but I'm not sure there were many/any people who had lots of Optimats. Unless you can either get a proper drawing of one or the real thing, the best bet might be to leave well alone.

Our Essemtec machine has what seems like a similar calibration routine. A large glass/ceramic plate covered in fiducials is used in conjunction with 2 smaller plates the machine picks up and moves around the large plate. The smaller plates came with the machine (so we can lose them perhaps) & the large glass/ceramic one is owned by the service engineer. I'm not sure what Dima were like but Essemtec are decidedly not keen on end users carrying out much more than basic cleaning type maintenance on the easily accessible parts and so are not that keen on users owning things like calibration kit.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #50 on: January 02, 2019, 10:03:43 am »
Is the machine actually out of calibration?
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #51 on: January 02, 2019, 10:29:06 am »
The PnP was probably setup while not level before transport so when we set it up level in the shop the pcb transport rails were slightly twisted which locked the axles. We noticed this only when we tried to load a pcb, it burned out the pcb belt drive motor.
See the quote above. Also, the machine was originally configured specifically for wide pcb's so only the front of the machine could hold feeders. The supplier has added a 'nest' (cassette) mounting beam at the back of the machine for us. So I'm not sure if the machine is really out of calibration but I reckon it won't hurt to do a full calibration when it's in working order again.

The calibration manual certainly appears to be written for the end-user. It's detailed and often talks about 'you' and 'the user', nowhere does it say that the process should be performed by a trained technician.
E.g. "This manual is written to help you calibrate the Optimat." and "To support the user in this calibration, a software program is provided, which guides the user through a menu, so that all items are calibrated in the correct order".

And some of the calibration tools as mentioned in the calibration manual are permanently fixed to the machine (e.g. some fiducials on the pcb transport rails and feeders). I suspect every machine came with a calibration set.
« Last Edit: January 02, 2019, 10:31:59 am by Styno »
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #52 on: January 03, 2019, 08:39:17 pm »
Today was not particularly a good day, we discovered more problems with the PnP.
- A segment in the fiducial camera lighting ring isn’t working. I suspect this to be an easy fix.
- It looks like one or two power transistors on the I/O VME card for the pcb conveyor burned out, as well as a darlington array ic. The card will be repaired or replaced.
- The new cassette base plate is unfortunately not made very accurately. The cassettes do not line up with the registration holes in the coveyor beam and, when installed with some force anyway, bend the conveyor beam. This bending is also the likely cause of the locked belt drive shaft earlier and the subsequently burned out motor/IO-card.

So more delays unfortunately, but tomorrow I’ll try to backup the software (DOS) and to start building a package and component library.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #53 on: January 03, 2019, 09:14:56 pm »
^^ lesson for everyone whos buying a PNP ( new or otherwise ).. Dont' commit to a job for it, until you have it all up and running and commissioned.     It will bite you .
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #54 on: January 04, 2019, 09:27:42 pm »
Heh, lucky we don’t have a big deadline close and our manual PnP is still operational as well.

Today we made copies of the computers. Working with diskettes again brings back old memories, like I still have Norton Commander musle memory. Also added DOS USB drivers so we can use USB sticks (with FAT16 filesystem) from now on. These work great and are free.
- Just unzip and copy the files on the harddisk
- Run “usbuhcil.com DisableLegacySupport”
- Run “usbdisk /DriveLetter:G”
If it works you may want to add the last two commands to autoexec.bat

I removed app pcb- and component configurations from the previous owner and started adding our own, that felt really good.

Also sorted a whole bunch of feeders/cassettes into ‘good enough’ vs ‘something wrong’ groups. Next is to refurbish some until we have the amount of feeders we actually ordered. All feeders will need some oil on various joints/hinges, but together with the new springs we’re getting should render them ‘like new’.
« Last Edit: January 04, 2019, 09:59:45 pm by Styno »
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #55 on: January 04, 2019, 10:08:36 pm »
I put USB-floopy disk emulators in my machines!
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Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #56 on: January 05, 2019, 10:00:28 am »
Yes, I could have done that as well, but using the usb on the compaq sff desktop inside the PnP does not require changing the hardware, I only needed to add two small programs.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #57 on: January 09, 2019, 08:47:17 pm »
The Optimat has a few basic package types and you have to pick one for each device that you add. E.g sot, soic, qfp, melf etc. The package types determine what package information you need to enter and configures the vision system.

I added a bunch of devices to the machine config. Many went without a problem even when I dind’t expect it, like the Microchip RN2483 which is a pcb subassembly with castellated ‘pins’. I chose Leadless Chip Carrier as the package type and within 5 minutes I had the correct lighting conditions set and a good vision recognition.

A small vqfn chip gave me much more trouble. It’s a 4 by 4 mm 24 pin package with a large ground pad and it was impossible to find a lighting condition where the package outline was visible without under-exposing the pads. Eventually I found that using the soic package type for configuring the vision the position and rotation of the part on the nozzle was correctly identified.

What can you do? I wonder if qfn packages even existed when this machine was built. The component camera uses purely IR illumination. I’ll try adding some visible light, perhaps it improves things.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #58 on: January 11, 2019, 08:49:12 pm »
Because the rear base plate was made inaccurately and the blown motor controller and the led ring problem (which appeared to be a bad solder joint somewhere, because at one point it worked correctly for a short while), the supplier offered to arrange a replacement machine on short notice. It arrived this morning. It’s 5 years older but these machines are old anyway, so okay, we want to move forward.

We started setting up when it became apparent various cassette guides were worn enough to give the cassette so much play that I was worrying about mispicks which I can’t accept and the supplier offered to replace them. Good.

Then the fiducial camera went dark. Luckily we traced this to a loose connector.

Then the component camera lost it’s h-sync signal. This was traced down to a broken wire in a connector which we fixed.

Then it was apparent that the component camera needed refocussing. So we followed the calibration manual and did that.

Finally I could start adding packages and during the fourth component I heard a cracking noise from the machine followed by a burning electronics smell. I rushed to switch the machine off, opened the electronics compartment door and was welcomed with a smoke cloud. So I was clearly done for today.  :palm:

The supplier will be back on monday to fix the problem with the old machine for spares. Hopefully it’s just a power supply...  I really hope this streak of bad luck ends soon!
« Last Edit: January 11, 2019, 08:54:02 pm by Styno »
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #59 on: January 27, 2019, 11:25:48 am »
So, after the problems with the electronics (we haven't checked but the supplier suspects a blown tantalum capacitor) we now have an Optima P&P that is built from two donors. The mechanics (frame, gantry and head) from an older machine and the electronics from a newer machine. In the past two weeks I've been calibrating the machine, refurbishing feeders and adding components.

I'm positively surprised by how 'easy' it is to calibrate the Optimat. There is a separate application that guides through a number of calibration step in a very detailed and userfriendly way. I.e. it tells you to "Open the hood, put the calibration nozzle in tool position 1, close the hood and press 'OK'" then the nozzle is picked up, brought towards the user and asks "Open the hood, place the plastic calibration fiducial on the nozzle, close the hood and press 'OK'" etc. The entire calibration procedure can be performed by the end-user without the need for a specially trained technician, though we needed to make a calibration tool ourselves (yay to still having some overhead sheets!). Of course there were some quirks, e.g. at some point the calibration program had difficulty rembering where to find the temperature calibration fiducial which was just tought in the previous step, but -as always- the 'Ein Reboot tut immer gut!"-rule applies.

Unfortunately the last calibration step (x/y/phi relation between fiducial camera and nozzle) is time-consuming and prone to error so I ended up manually editing the Optimat settings file to correct the x/y offset. There is still a phi error but I was finally able to place a 0603 resistor on a panel of 12 pcb's and I'm very happy with how repeatable the placement is as I couldn't spot any difference in the placement.

I only have four questions left:
- Figure out which of the two settings that (indirectly) influence the rotational calibration needs tweaking.
- Figure out how to prevent the machine spitting out the assembled pcb. There is no in-line oven behind it and having the pcb drop on the floor is not very helpful :p
- The component camera processing has difficulty identifying the corner pins of a big castellated RF-module we use a lot. But it appears to correcly calculate the rotation on the nozzle so hopefullly it will place correctly.
- Some 8mm feeders feed 4mm per actuation, some feeders of the same type feed 8mm or 12mm per actuation. I haven't yet figured out how to keep 0603 components covered by the feeder mechanism (to prevent them jumping out) and feed only 4mm per actuation.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #60 on: February 16, 2019, 09:05:17 pm »
It's been a while but we've been busy in the mean time. More than 100 single boards and panels have gone through the p&p and we're quite happy with the machine. The fastest panel to date was 30 minutes for 590 components, about 50% it's maximum rated speed, matching the expectations we had before we bought the machine and there is still room for improvement. A few things we learned:

The feeding problems mentioned in the previous post were caused by the cover tape spool tension. If the spool slip is too heavy then the spool pulls on the tape more than the advance pin's movement. The result is either an advance more than one hole or the tape advance ends up in between holes. The spool slip tension is regulated by loosening or tightning an M17 nylon insert lock nut (DIN 1805) pushing the spool against a spring washer and nylon sliding bearing. Some of these feeders are 15+ years old and the nylon of the lock nuts has dried out so the feeder won't stay tuned (often loosening after a while causing the cover tape to stay attached to the tape). Luckily these nuts are still readily available so we ordered some from Conrad. We found some feeders with the nut glued in place with Loctite, not useful when a cover tape needs a different setting and a pain to undo ...

Increasing the feeder actuator air pressure fixed a problem we had where the retracting lip (that holds the component steady in the pocket until pickup) was not moving back soon enough when the nozzle came down to pick up a component. Increasing the pressure on the actuator means that the actuator moves faster and the lip is pulled back earlier. Too much pressure on the actuator leads to more components jumping around so just fast enough is the trick. Another tip is to have a camera with slowmotion video function at hand, reviewing problematic pickups in slo-mo or even frame-by-frame is very enlightening.

A very light 0603 schottky diode in a plastic tape had a tendency to jump around at whichever actuator pressure and reducing the z-axis movement fixed this, though I'm not quite sure how. It's not the nozzle that makes the part jump, it's the actuator moving the retaining lip backwards. I haven't figured out why reducing the z-axis speed works, it seems like there is a second electronically controlled air valve somewhere that reduces pressure (or volume) when the z-axis movement is reduced? This needs more investigating, however, changing the setting works and that's what counts.

Some small problems left:
On one board we use two different 4-pin DIP devices , the molding of one of the devices is slightly different than the other and I can't get the vision system to reliably detect the outline position of the device and the orientation on the nozzle while the other device is detected flawlessly. It has something to do with the smoothness and molding artefacts of the plastic on the bottom and perhaps also the 'shinyness' of the feet. For now we place it by hand as the machine rejects about half of the devices.

Sometimes a random feeder (with resistors or capacitors in paper tape) refuses to pick a component a few times in a row, the machine will complain, we press Enter (try again) and everything works just fine again. Not sure if this is caused by differences in required cover tape peel strength (all tapes are still quite fresh), something else that needs tweaking or just random noise. It's not a big deal anyway.

A bit more worrysome is that the alignment of the components is not the same between panels. On one panel all components are placed dead center but on another they are all shifted a few tens of a mm to one side (perhaps up to 0.5mm in extreme cases!), always to the rear of the pcb on the x-axis (along the conveyor direction) and way outside the accuracy that the machine is capable of. The boards still reflow fine but sometimes we precautionary manually realign an SOIC-8. The cause is yet unknown. The panels have tooling fiucials that are used for the vision alignment and performing an extra temperature calibrarion does not help. Any tips are welcome.
« Last Edit: February 16, 2019, 09:19:17 pm by Styno »
 

Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #61 on: February 17, 2019, 02:12:11 am »
On our Philips CSM84, the small feeders (8 and 12mm) are operated mechanically by the head.  The larger feeders are air operated, and there are adjusters on EACH feeder for speed of the air cylinder stroke.  The air cylinder operates the cover blade, sprocket advance and cover tape pull.  So, you can set the stroke speed for each part based on how easy it is to flip.  If the embossed tape is properly made for the part, it should be impossible for the part to flip.  So, maybe these parts were re-reeled onto the wrong tape that has too big/deep a pocket.

As for fiducial registration, the sensor needs to be tuned to accurately pick up the centroid of the fiducial spot.  On our CSM, it seems to either find the fiducial properly or not at all.  One issue is some of the fiducials have an uneven solder plate, and the algorithm could incorrectly computer the centroid based on differing reflectivity toward the camera.

Jon
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #62 on: February 17, 2019, 05:02:03 pm »
The part could have been re-reeled, how can one tell? Anyway it sometimes jumped half way up the nozzle, I even saw the nozzle ‘grabbing” a part mid-air once :clap: then continued down into the pocket and lifting two components after that  :-//

The Optimat feeders are purely mechanical and all, from 8 to 32 mm, are actuated by the air cilinder mounted on the head.

I never experienced the machine not recognising a fiducial at all but the manual states that for best accuracy a double cross fiducial (looks like this:#) should be used.

Perhaps as an experiment I should ask the board house to skip HASL on the fiducials, just bare copper. Or only use ENIG.
 

Offline mrpackethead

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #63 on: February 17, 2019, 06:18:30 pm »
I dont' think i've used a HASL board in a long itme.  Its all ENIG, as its so much flatter.   If your doing QFN its mandatory.
On a quest to find increasingly complicated ways to blink things
 

Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #64 on: February 17, 2019, 06:46:42 pm »
The part could have been re-reeled, how can one tell?
Hmm, not always easy.  I once got some salvaged parts that 50% had been powered up with the chips backward!  The giveaway was the date codes were all over the place on the same reel.  Diodes are not big enough to have date codes, though.
Quote
Anyway it sometimes jumped half way up the nozzle, I even saw the nozzle ‘grabbing” a part mid-air once :clap: then continued down into the pocket and lifting two components after that  :-//
Yes, if the nozzle is not centered on the flat top of the part, it can flip the part sideways or fully upside down.
Quote
The Optimat feeders are purely mechanical and all, from 8 to 32 mm, are actuated by the air cilinder mounted on the head.
So, then the problem is the cover blade is not keeping the part from jumping in the pocket.  There should be very little space above the part until the cover blade is retracted.  This has worked VERY well on my CSM with Yamaha-style feeders, and flipped parts are quite rare.  Mis-picks are more common the smaller the parts are.
Quote
I never experienced the machine not recognising a fiducial at all but the manual states that for best accuracy a double cross fiducial (looks like this:#) should be used.
I use round fiducials only.  The CSM can use plated through holes for fiducials, or anything that is solid copper, but they recommend round or octagon.  You have the option of XY or XYX fiducial measurement.  The XYX uses the result of the X scan centroid for the Y scan, and then after the Y centroid is obtained, goes back and re-does the X scan.  I do that on boards with fine pitch parts, not needed on ordinary boards with 0805 and SOIC parts.

I'm not sure what your # fiducial is.  I have seen single cross designs used on some boards.
Quote
Perhaps as an experiment I should ask the board house to skip HASL on the fiducials, just bare copper. Or only use ENIG.
Bare copper should be fine until it tarnishes.  Most (like 99+%) of my HASL fiducials are just FINE.  More common is a solder paste fingerprint over part of the fiducial.  But, I have had just a FEW fiducials that had a kind of barrle-shaped blob on them, and my "beam sensor" needs a really flat, reflective surface to bounce light right back into it.

Watch out for gold finishes, great for long-term solderability, but if not done right, you can get HORRIBLE black pad issues.  If it doesn't solder properly on the first try, rework is some kind of nightmare from hell!  I tried it once (I think it was just gold flash on bare copper, NOT ENIG) and NEVER AGAIN!

Jon
« Last Edit: February 17, 2019, 06:49:38 pm by jmelson »
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #65 on: February 20, 2019, 04:22:27 pm »
I dont' think i've used a HASL board in a long itme.  Its all ENIG, as its so much flatter.   If your doing QFN its mandatory.
On this particular board the smallest package is a 0.65mm pitch SOIC-8, so (lead-free) HASL is fine and a bit cheaper than ENIG. On the RF-board with 0.5mm pitch QFN ic's I use ENIG indeed.

Yes, if the nozzle is not centered on the flat top of the part, it can flip the part sideways or fully upside down.
Yes, but in this case the device already jumped before the nozzle came down, just by the feeder action.
Quote
So, then the problem is the cover blade is not keeping the part from jumping in the pocket.  There should be very little space above the part until the cover blade is retracted.  This has worked VERY well on my CSM with Yamaha-style feeders, and flipped parts are quite rare.  Mis-picks are more common the smaller the parts are.
That's how it works on the Optimat as well but the part jumped constantly after the blade retracted and before the nozzle could enter the pocket.
Quote
I use round fiducials only.  The CSM can use plated through holes for fiducials, or anything that is solid copper, but they recommend round or octagon.  You have the option of XY or XYX fiducial measurement.  The XYX uses the result of the X scan centroid for the Y scan, and then after the Y centroid is obtained, goes back and re-does the X scan.  I do that on boards with fine pitch parts, not needed on ordinary boards with 0805 and SOIC parts.

I'm not sure what your # fiducial is.  I have seen single cross designs used on some boards.
The double cross fiducial is mentioned in IPC-SM-782A fig. 3-13.
 

Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #66 on: February 21, 2019, 09:25:59 pm »
Yes, but in this case the device already jumped before the nozzle came down, just by the feeder action.
Well, there must be a problem with the feeder.  There just shoudln't be much vibration when the cover blade is retracting to make the part jump.  On my Philips machine, this does not happen, but then that machine is 700 Kg and the feeders mount to a massive steel plate that keeps them from bouncing.

Jon
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #67 on: April 12, 2019, 09:33:35 am »
Time for an update. :)
The problems with the parts jumping around is primarily solved by reducing the pressure on the feeder actuator cylinder. This means that on some other feeders the z-axis movement needs to be reduced because a slower actuator sometimes means that the component retainer lip is still located above the component when the nozzle tries to grab it. This turned out to be a finicky thing but the cost of a slightly reduced CPH does not weigh up against more reliable picks.

Then there were problems with properly recognizing some -otherwise rather straightforward- components. E.g. we had one dip-4 package that was recognized without a problem and then another that turned out to be a total bitch for the vision system. The solution here turned out to be a to reduce lighting from the 6 led-sections to just one. For other problematic packages falling back to the simple "SMALL" package setting (normally used for chip resistors/capacitors) often did the trick. In that setting the vision system does not attempt to recognize legs/pads but only looks at dimensions.

We assembled some double sided panels with a large pcb package (Microchip RN2483, roughly 18 by 27mm) and 0.5mm pitch QFN mcu, hundreds of pcb's and all of them placed accurately without needing attendance except for exchanging RN2483 trays every 10 minutes. I sure wish those would be available on reel and those fancy P&P's with tray stackers suddenly look really appealing!

Unfortunately the M17-1.0 nylon insert lock nuts (DIN 1805) we ordered as spares for the feeders do not fit. They have the correct outer diameter and threads per mm but perhaps the angle of the thread is different. Anyway, the nuts don't fit and I haven't yet found a supplier that is able to supply the correct lock nut.
 

Offline Nauris

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #68 on: April 12, 2019, 04:50:57 pm »
A

Unfortunately the M17-1.0 nylon insert lock nuts (DIN 1805) we ordered as spares for the feeders do not fit. They have the correct outer diameter and threads per mm but perhaps the angle of the thread is different. Anyway, the nuts don't fit and I haven't yet found a supplier that is able to supply the correct lock nut.
A drop of wood tar (or something else sticky) may stop it loosening itself and still allows adjustment unlike loctite.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #69 on: April 17, 2019, 07:17:44 am »
A drop of wood tar (or something else sticky) may stop it loosening itself and still allows adjustment unlike loctite.
Thanks for the tip! Until now we've used some pipe-fitters teflon tape.
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #70 on: September 20, 2019, 09:05:00 am »
Unfortunately the M17-1.0 nylon insert lock nuts (DIN 1805) we ordered as spares for the feeders do not fit. They have the correct outer diameter and threads per mm but perhaps the angle of the thread is different. Anyway, the nuts don't fit and I haven't yet found a supplier that is able to supply the correct lock nut.
Well, that turned out to be a wild goose chase...
TL;DR Apparently the threading on the feeder axle we used for our nut-replacement experiment was damaged, we tried another feeder and this time the replacement nuts fit as you would expect. Aargh! Went to visit several businesses and scour the internet for hours for nothing.

I contacted Nordson Dima for help on this topic and while they officially do not provide support anymore their service was excellent! They were able to tell what type of nut they used and how they modified it for use on the feeder. The nuts need modification because the locking action would otherwise be too strong, so they use a tap to machine a (slightly different) thread in the plastic to give some more play. We used this information to mill one of the DIN 1805 M17/1.0 nuts, removing all but the last 0.1mm plastic. This seems to work fine too.

The support technician from Nordson found a few original nuts and offered then for a fair price so we ordered them as well.

Excellent service, should have contacted them earlier  :-+
 

Offline Styno

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #71 on: November 05, 2019, 01:49:06 pm »
Help! I'm specifically looking for 44-mm feeders for our Dima Optimat SMPM-2000, these have partnumber SMPM-6440.

But while I'm at it:
- extra feeders (8mm/2mm pitch: SMPM-6082, 16mm: SMPM-6160)
- cassettes (SMPM-5000)
- large-reel holders (SMPM-5051)
- cut-tape holders (SMCS-400x)

Are also welcome! Please send me a PM  :-+

And to continue toe user experience reports:
- Last week we had an issue where component pickup failed. The nozzle would move down at the pickup position retracting halfway down and continue to place the component only to find out that the camera rejects the missing component. This turned out to be caused by a constipated nozzle and the pressure sensor sensing a vacuum when it starts to measure half way on it's way down. Poking a strand of copper wire through the nozzle fixed this.
- We learned that exporting a misformatted placement file from CAD can cause the pick and place software to crash halfway a job. This is prevented for the future by adding proper formatting in the output stage of the CAD-export and extra checking of e.g. partnumber lengths.
« Last Edit: November 05, 2019, 01:51:13 pm by Styno »
 

Offline jmelson

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Re: Bringing PCB assembly in-house with Dima Optimat?
« Reply #72 on: November 05, 2019, 07:48:00 pm »

- Last week we had an issue where component pickup failed. The nozzle would move down at the pickup position retracting halfway down and continue to place the component only to find out that the camera rejects the missing component. This turned out to be caused by a constipated nozzle and the pressure sensor sensing a vacuum when it starts to measure half way on it's way down. Poking a strand of copper wire through the nozzle fixed this.
Our old Philips CSM-84 checks the vacuum sensor before every pick-up.  if it shows vacuum, it goes to the dump bin and tries to clear it with up-down strokes and blow-off pressure.  if that doesn't work, it stops and asks for help.

The nozzles need to be cleaned every once in a while.  They do get dirt, solder paste and etc. on them.

Jon
 


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