New Pick and Place design ideas

[Koen]

Add two holes to the PCB and the stencil. Then index both with dowel pins. Simple, efficient and cheap.

[mikeselectricstuff]

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)

[rx8pilot]

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?

[mikeselectricstuff]

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.

[vzoole]

Or check the Eurocircuits stencilfix how it works.

EC stencilfix

[Kjelt]

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.

[l0wside]

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

[Kjelt]

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.

[l0wside]

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

[Kjelt]

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.

[Koen]

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.

[JuKu]

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.

[mikeselectricstuff]

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.

[ar__systems]

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.

[thommo]

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.

[D3f1ant]

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.

[l0wside]

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

[mikeselectricstuff]

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.

[Kjelt]

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.

[thommo]

Mike, what are you using to create your Panelized PCBs in [programme]?

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.

[mikeselectricstuff]

Mike, what are you using to create your Panelized PCBs in [programme]?

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)

[mrpackethead]

I panelise with altium.. its got some tools that make it *eaiser*

[jmelson]

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

[jmelson]

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

[jmelson]

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