----- Original Message -----
Sent: Saturday, July 05, 2003 1:37
AM
Subject: Re: [TN] Nickel separation
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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