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measument of paste thickness after Screen Printing

Dhanashekar

#30389

measument of paste thickness after Screen Printing | 4 September, 2004

Can anyone suggest me if it is necessary to measure the paste thickness after contact Screen printing.Is it a very vital parameter for the production process?

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#30390

measument of paste thickness after Screen Printing | 4 September, 2004

Yes it is vital for process control.

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C Lampron

#30404

measument of paste thickness after Screen Printing | 7 September, 2004

Dhanashekar,

Yes this is an important proces control tool. This will show if you printer setup is correct however, I put more importance on coverage. If your paste height is 1 mil shorter than it should be, you may need to look at your printer setup, but you will still produce an IPC aceptable joint. If you have a skip or partial release (due to setup or lack of paste) you will have an insufficiant joint.

The problem that I see is most paste height systems only look at select pre-programmed areas. If there is a skip and it does not happen to be at one of these area's, it may go undetected until post SMT inspection or even worse by the customer.

I speak from experience. We have a paste height measurement system. When this was implemented, the general consensus at the plant was that we will no longer have printing related issues. They actually got worse as the operators seemed to pay less attention to the printing as they thought problems would be identified by the paste height. This is not always the case.

Consider you options carefully.

Good Luck

Chris

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Rob

#30407

measument of paste thickness after Screen Printing | 7 September, 2004

Hi Dhanashekar,

I'm with Chris on this one, unless you are carrying out 0201 or ultra fine pitch placement it's a helpful but not critical tool. We found most print errors were avoided using the 2D vision on the printer, combined with plenty of auto stencil wipes, and keeping the paste at the correct temperature.

Cheers,

Rob.

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#30433

measument of paste thickness after Screen Printing | 8 September, 2004

I'm in a similar situation. We have a pre-historic semi-automatic printer that does a decent job, but would like to get an automatic printer. I've only just begun looking into the different options available, but would like one that could inspect the print. It sounds like the inspection points are typically pre-programmed during initial setup.

Does anyone know if there are systems on the market that can give a complete inspection after print? ...and pull that data into Excel for SPC purposes?

...I'm sure I'm about to be nailed by a salesman...

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Rob

#30446

measument of paste thickness after Screen Printing | 9 September, 2004

Hi Chris,

We use MPM's, where you can set the paste inspection to look at whatever you want it to (remember this does slow cycle time down) and we swear by them. However I have also met many happy DEK users who believe their machines are equally as wonderful.

You could also pay lots of money for a dedicated paste inspection machine - but this would depend on your complexity & throughput of boards.

You can also get AOI machines that can be wheeled into any part of the line (paste, pre & poste reflow) to monitor & refine the process if you can't justify the cost of a dedicated in line paste inspection machine. However this won't give you constant feedback if it's doing another job at the time.

Good luck with the Sharks. Sorry, salesmen.

Rob.

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Martin

#30462

measument of paste thickness after Screen Printing | 9 September, 2004

Shark here, reporting for duty....

www.kohyoung.com

High speed, 3d 100% paste inspection.

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