Howard:

I assume that the Copper whisker is against the laminate, not above it?
If that is the case, it is almost certainly caused by incomplete etching.
And if that is the case, the problem is almost certainly not caused by the
etching department.
My guess is that you are stripping photoresist using straight Caustic Soda.
(Most common strip chemistry in Taiwan)  If that is the case, the boards
probably tarnish badly in the stripper.
Tarnish on the Copper can interfere with (slow down) etching by the
ammoniacal type etchants used for etching outerlayers.
Figure out how to get panels with no tarnish to etcher, and you probably have
solved the problem.

Regards,

Rudy Sedlak
RD Chemical Company

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