Mike,
Can I/we assume that you have put into practice all the other "tricks" for
eliminating entrapped air and gas?
Such as, the Bump (all process tank stages on electroless line) or
ultrasonics, angling panels, and the best possible cleaner/conditioner for
wetting of the holes?
Double electroless is a kind of band-aid... You remove some part of the
first layer in the microetch, you know. It always seems to me that
"band-aids" or re-works at one part of a process tend to produce more
"band-aid opportunities/requirements" downstream.
Patty
Patricia J. Goldman
PPG Industries, Inc.
412-492-5516
[log in to unmask]
-----Original Message-----
From: Mike Bailey [mailto:[log in to unmask]]
Sent: Monday, April 10, 2000 11:30 AM
To: [log in to unmask]
Subject: [TN] Double Electroless Processing
We have long had a practice regarding the processing of thick panels with
high aspect ratio holes. We perform standard desmear/electroless deposition
followed by a 10 min electrolytic strike plate. We then re-process the
panels through electroless copper. This has served us well in terms of
protection from "bubble" voiding, but has become burdensome on our pattern
cu throughput. In all honesty, we have not seen bubble voids, but are
probably a bit paranoid and hesitant to break the habit. The logic of this
process has been that if you must re-process the panels, why subject 99.99%
of the holes to additional electroless. It seemed better to lock them in
with a strike plate first.
Anyway, I was in a meeting the other day and it was suggested that we simply
re-process the panels a 2nd time thorough electroless copper and eliminate
the strike plate altogether. Being the composed individual that I am, I bit
my tongue, but was thinking. WHAT PART OF INTERCONNECT INTEGRITY DON'T YOU
UNDERSTAND?????
While I know that we have all done this double pass at one time or another,
and it probably appeared to work satisfactorily, you must admit that the
main objective at the time was just to get the panels through and avoid
scrapping them at that point.
I would appreciate a reality check and some feedback on this issue.
Thanks in advance
Mike Bailey
Director of Engineering
McCurdy Circuits Inc.
4900 E. Hunter Ave.
Anaheim, CA 92870
Phone: 714 507-4900 Ext 253
FAX: 714 507-4911
e-mail: [log in to unmask] <mailto:[log in to unmask]>
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