Most immersion Silver baths contain an anti-tarnish to prevent discoloration,
as you see, for instance on your silverware at home, if you have the
expensive stuff..

So, it could be a lack of, or lowered level, anti-tarnish in the plating
bath... most of the immersion silver baths use triazole as the anti-tarnish, and
there is a pretty easy test for triazoles from the Hach company, out of
Colorado.

If it is Copper showing through, as has been suggested, this could be because
the silver deposit is porous, which can come from plating on to a dirty
Copper surface...recall that the step before plating silver is to develop the
soldermask, which is an "iffy" process, and has been known to leave some material
behind.

If the surface is dirty, the silver will not adhere real well, and a tape
test would probably show that.

Regards,

Rudy Sedlak
RD Chemical Company

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