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Thu, 23 Feb 2006 15:41:13 -0800 |
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Scott,
I've been reading the posts replying to this question. From your
description and the responses from others, the problem sounds very much to
be a copper plating issue. Specifically, super saturated air in the plating
solution causes this. Pits, mouse bites or whatever you want to call them
are one of the reasons more advanced shops have gone to airless agitation in
their copper plating baths.
One of the dry film suppliers did a huge study on this years ago when pits
were a general problem and driving board fabs crazy trying to find a
solution. No question that developing/rinsing issues can exacerbate the
problem. Further, some films will develop OK but leave a sidewall that has
striations that can catch and hold air bubbles. If you've looked at the SEM
of a resist sidewall you can see that some films are worse than others in
how clean their sidewalls look after developing. Simply turning off the air
in a plating bath and running boards as a test won't really work unless your
fab lets the bath sit for 24 hours (without any air agitation) to properly
de-gas.
Sincerely,
Roger Mouton
EIMC - Advanced Plating Technologies
www.smartcatshield.com
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