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Need help on PCBA Cleanliness Standards and Specs

tomd44

#26440

Need help on PCBA Cleanliness Standards and Specs | 25 November, 2003

We are trying to establish requirements and process controls for completed, cleaned SMT assemblies. We have problems with our high impedance circuits (100 meg ohms) being affected by residue. Some boards require additional cleaning cycles to remove surface contamination. Our SMT process is at a different site, so I don't know the capability of the assembly house's process. We have specified aqueous flux and DI wash, as we've had nothing but trouble with No-Clean processes. I've looked at IPC TM-650, MIL-2000A, but it's not clear how to specify the maximum contamination levels or how to validate in- process.

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Gabriele

#26441

Need help on PCBA Cleanliness Standards and Specs | 25 November, 2003

Try to see J-STD-001 Chapter 8.Cleaniness Requirements. Also you could info also on ASTM D5127-99.

Rgds

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#26444

Need help on PCBA Cleanliness Standards and Specs | 25 November, 2003

We had a similar problem on the high impedance front end of a MOSFET amplifier a few years ago.

If your situation is like ours, the issue is not what a consensus specification [like J-STD-001] defines as an upper limit, but what your product is defining [before your eyes] as the limit. Seriously consider involving a failure analysis laboratory in: * Assessing the contamination level on your product. * Determining practical go / nogo limits. * Instituting effective process control methods for your assembly troops.

Laboratories to consider are: * Trace Laboratories 1150 W. Euclid Ave Palatine, IL 0067-7397 847-934-5300 Fax 4600 http://www.tracelabs.com info@tracelabs.com Jeffry Schutt * Robisan Laboratory 6502 East 21st St Indianapolis, IN 46219 317-353-6249 fax 317-917-2379 http://www.robisan.com mail@robisan.com Susan Mansilla * Foresite, Inc. [Contamination Studies Laboratories] 1982 S. Elizabeth St. Kokomo, IN 46902 (765) 457-8095 Terry Munson * ACI/EMPF One International Plaza Suite 600 Philadelphia, PA 19113 610-362-1200 EXT 248 Fax: 1290 Mark Thaler mthaler@aci-corp.org

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CAL

#26450

Need help on PCBA Cleanliness Standards and Specs | 26 November, 2003

Dave- Mark Thaler is no longer at ACI/EMPF. He left a few Years Back.

Best to use Guy Ramsey gramsey@aciusa.org 610-362-1200 x 107

Cal

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#26460

Need help on PCBA Cleanliness Standards and Specs | 28 November, 2003

Best to establish what type of residue is causing this problem and then stamp it out.Speak with SCOPE Labs who offer PCB extraction followed by IR and IC work. So many problems with porous resist at present and NON ionic materials that you really need to identify what is causing this issue. Tel 001 708 798 8300 Jim Hevel Hope this helps you

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Daniel Werkhoven

#26475

Need help on PCBA Cleanliness Standards and Specs | 2 December, 2003

Dear Tom, As manufacturer of solder chemicals for the electronic industry we know we can help you out with your problem. To go no clean you most only organise that the chemistry that stays behind on yr PCB will not cause any problem during the life of the PCB.When you want to clean those residues away then you most be more selective in your chemical selection, there they have to be compatible with your cleaning medium.If you could use our help then please send me a mail and specify your actual working process. looking forward to hear from you. Daniel

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