Hi Rich,

We have seen this discoloration a few times also.  Our analysis showed, in
our cases, that the discoloration was due to copper near the surface of the
silver layer. The silver layer wasn't too thin and the copper did not appear
to be diffusing up through the silver, but it appeared that the copper may
have been co-deposited with the silver layer.  Solder testing of the suspect
boards showed that they soldered okay, so we accepted the boards. We
notified the board vendors of our findings and never heard anything back (at
least I didn't hear anything) about the cause, but we also have not seen
this again from those vendors.

Wade McFaddin
Nextek Inc.
256-772-1995 ext.1064

-----Original Message-----
From: Richard Kraszewski [mailto:[log in to unmask]]
Sent: Wednesday, June 16, 2004 9:13 AM
To: [log in to unmask]
Subject: [TN] Yellow Discoloration of Immersion Silver Boards

We are seeing yellow discoloration of Immersion Silver Boards right out
of the package from our board house.  They seem to solder fine, however
this is causing some concern with our customer.  I suspect that it could
be a thin film of  silver bromide or silver carbonate both which are
yellow powders.

Any one seen this before?

What is it?

How does the board house remedy this situation?

Any associated concerns or other bits of wisdom?

I would truly appreciate any input.


Rich Kraszewski

Advanced Manufacturing Engineer - KEDS

Phone:  260.925.8919









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