In a message dated 8/28/00 5:08:13 PM EST, [log in to unmask] writes:

<< Gary,
 The Purple stain probably is caused by the gold bath brightened.  Nickel and
 Cobalt are used in varying degrees to produce different levels of hardness.
 The Cobalt, I think, is absorbed into the laminate due to low resin content
 and/or low bath plating efficiency.
 The heat of Reflow, like magic, oxidizes it to a visible molecular state. To
 my knowledge no one has been able to show any functionally detrimental
 problems with this stain. >>

Hi Gary!

The ol' "Purple Plague"...run into that a while back and like Robert said,
it's from the gold plate bath. It doesn't hurt anything other than looking
ugly as far as I know too...

We ran into that when building some PCI graphic accelerator cards for a
customer. They sold them retail so they couldn't have a bunch of purple
stains around the fingers in the laminate...(even though your average
consumer probably wouldn't have noticed it anyway).

But we were really scratching our heads over that problem when it first
popped-up. Tried washing the boards first in freon (back when everybody used
it), no joy. Like Robert said, send it through reflow and it's like magic!
Purple laminate!

-Steve Gregory-

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