I am looking for some input regarding a possible cause for a problem we are
having with one board, part number.

We recieved a lot of boards from a vendor, all with the same date code. This is
one of meny boards we have recieved and are still recieving.
This board, however, is causing problems after wave soldering, by the soldermask
peeling, reveling bare copper.

The boards are 4 layers, with a thickness of .093". They are SMOBC/HAL boards.

The boards are assembled and then wave soldered using water soluble flux. The
mask begins peeling during water wash in our Trieber SMT Cleaner.

The wave temperature is 500F. Kester Water soluble flux #2235 is used with
Kester #4662 thinner to reach SG. The flux is applied with a foam fluxer.
Preheat temperature is 220F.

The mask does not peel prior to wave soldering, only after.

My inital feelings is that there was contamination left on the copper prior to
the soldermask operation. The vendor feels, since the mask dosen't peel prior to
wave soldering, and didn't peel prior to their shipping, the problem is in our
process.

This is occurring with one part number, one single lot of boards from one
vendor. We have not experienced this situation with any other of this vendors
boards, or any othe vendor's boards.

Any Ideals?

All input will be appreciated.
Sincerely,

____________________
Richard E. Ackerson
Sr. Industrial Engineer
ABB Automation, Inc.
Electronics & Systems Assembly
Phone: 440-585-7646
Fax: 440-585-8860
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