Gabriela:

We saw something which I suspect is related to this often in the old days of
fusing Tin/Lead on the PCB...and I would bet the cause of the problem is what
is causing your problem.

In the old days, they would immerse the board into a fluoboric acid solution
then into the (fluoboric based) Tin/Lead plating solution, and we saw
non-adherent Tin/Lead deposits (they were called "dewetting") if the Fluoboric acid
pre-dip had enough Copper, and the boards were left long enough.

The Copper in the fluoboric acid pre-dip would react with the Copper on the
boards to create an insoluble (and invisible) Cuprous salt deposit on the
Copper.   You could plate over it, but the plating was non-adherent.

Suspect the same may be happening to your board... The fabricator is parking
the board in an acid pre-plating dip, and not changing the acid dip often
enough, and picking up Copper in the acid, which is causing you your problem...

And remember the wise words someone once said, "Free advice is often not
worth what you paid for it...:-)"

Rudy Sedlak
RD Chemical Company

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