Hi Angie - if your gold surfaces look like copper then you most likely have
a copper diffusion issue. You don't mention what type of gold finish you
have (e.g. electrolytic or immersion) but the connector designers have
yards of data demonstrating that a gold finish on a copper basis metal will
have copper diffusion problems. That is why most gold finishes you find in
the industry today have a nickel underplate to prevent the copper and gold
diffusing together. A Scanning electron microscopy analysis or a good cross
section can show the copper diffusing into the gold. Good Luck.

Dave Hillman
Rockwell Collins
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[log in to unmask] on 02/25/98 01:12:27 PM

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To:   [log in to unmask]
cc:    (bcc: David D Hillman/CedarRapids/Collins/Rockwell)
Subject:  [TN] Gold surface finish




Hi,
I have a question on Gold surfaces. It seems that one of my assemblies has
a
weird film or contaminates on the pads.  The board is double sided, we ran
one
side and then it sat (shortages) for a week. It almost looks like copper!
We
did check incoming boards before placing parts and it seems they have the
same
problem but not as bad. I guess after wash this problem got worse. Has
anyone
had this problem before and if so, what was the cause?
Thanks in advance
Angie
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