Mike,

I for one am in favor of a double electroless step on high aspect ratio
holes. Only because I have used it many times in the past as a last resort
and found marked improvement. We have shadow now so this doesn't apply to
our current processing.

However, you seem to indicate that your copper strike is producing
acceptable yields but someone wants to eliminate it..because of time
consumed in the copper tanks I suspect. The question that comes to mind is
if you have voids due to bubbles ( air entrapment) in the  electroless
process, I don't see how a copper strike would solve it. The void would
already be there. If electroless was missing, what is the strike plating to?

Perhaps your electroless process is better that you think. I wonder what
would happen to your yields if you simply removed the strike and see how
your original electroless deposit would stand up.

Just my thoughts,

Ed Cosper


----- Original Message -----
From: "Mike Bailey" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, April 10, 2000 11:29 AM
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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