Rudy,
Thanks for the feedback. Data I've gotten back from the board vendor in
China is that the finish is only 1-1.5 microinches thick. This sounds like
it could be the issue we're seeing as that doesn't seem thick enough to
adequately protect the nickel to me. Out of curiosity, would there be any
visual indication of nickel oxide formation? The pads we're seeing are very
shiny looking but I'm not sure if that's indicative of good or bad plating.
Regards,
Rick Thompson
Sr. SMT Process Engineer
SMTEK International, Inc.
+1 (805) 532-2800
[log in to unmask]
===== Original Message from [log in to unmask] (TechNet E-Mail Forum.) at
1/27/03 12:59 pm
>Rick:
>
>Plating is a process of adding electrons to a metal ion in solution causing
>it to revert to the metallic state. The differences in types of plating are
>due to where the electrons come from.
>
>In flash plating, aka "electroplating", the electrons are delivered by
>connecting the part to a rectifier, which "pumps" them in.
>
>In immersion plating, the electrons are donated by the substrate metal, in
>this case Nickel, as it becomes an ion, and goes into solution, while the
>receptor Gold ions deposit as the metal.
>
>I would suspect that for a given thickness (and immersion plating is self
>limiting in thickness, once all the Nickel is covered, plating stops) flash
>plating would have more tendency to be porous, thus opening up the
>possibility of Nickel corroding, and the oxide coming through on to the
>Gold.
>
>
>Good luck
>
>Rudy Sedlak
>RD Chemical Company
>
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