Have you looked at your air agitation.  Many voids are caused by entrapped
air bubbles.

Dick Desrosiers
D-Squared Associates
209-952-5563
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-----Original Message-----
From: TOE /Torben Østeraa <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Tuesday, June 29, 1999 3:43 PM
Subject: [TN] Voiding, through plating, conventional


Dear collegues,

I have run into a problem of sporadic ' voiding ' in my through plating
process. the problem has the following characteristics:
- is observed a few times per month
- affects all materials ( fr4, bt/epoxy, kapton, GI, teflon[s] )
- on kapton-containing builds ( i.e. rigid-flex ) , voiding takes place
predominantly
on the kapton surfaces. Typically, all the kapton is without coverage.
- I have not (yet ) ben able to establish any correlation with time of day,
batch maintenance or other obvious influences
- Is independent of type of desmear, plasma or permanganate, even
kombinations
have failed. Therefore, point of my focus at the pth-line itself.
- The obvious cause would be under catalysation, so an alkaline substitute
for my
present acid conditioner has been tried. Nice results, but the expected poor
hole wall
adhesions is just not good enough to prevent excessive hole-wall-pullaway
during HASL.
- Supplier is no help ( sorry to say.... ).

- Line chemistry is Shipley, Cleaner/cond 815 ( acid) , Etch 3330 (
persulfate/acid stabil. ).
Catalyst 3344 + predip 3340, Accel 19H, copper Cuposit 328 ( 'classic' low
build ), Acid strike 4 microns.
- Water rinses are all 'fresh' tap-water. ( good quality in our part of the
world )

Any advice or hint in this matter is highly welcome

regards

Torben Østeraa
Printca AS
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