What's to solve?

Apparently the boards soldered OK, so it sounds like you are only talking
about cosmetics. No long term reliability problem.

Talking with the PCB supplier about getting an anti-tarnish applied over the
ImAg will help with the cosmetics.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tuyen Tran
Sent: Thursday, July 17, 2014 11:42 AM
To: [log in to unmask]
Subject: [TN] Staining immersion silver coating on ground plane after
assembling

Hi Everyone
We received some PCBs where the finish surface was good, but after we ran
reflow about ten days, the ground plane with immersion silver coating that
were not covered by solder paste look to be stained on surface. 
We known the chemical silver [Immersion Silver finish] surface is very
sensitive to surrounding condition, it is easy to stain from oxygen/water
vapour or production time exposure in the air.
We are looking for document on staining metal of the finished board. Has
anyone else experienced something similar phenomenon or anyone have an idea
to solve this?
Thanks
Tuyen Tran.

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