John,
        Sorry, I got wrapped up in my story (previous posting), and forgot
to answer your question.

By the mid-1980, the process had abandoned the flash plate, and the scrub
for outerlayers.  In the late 80's and early 90's, we used Shipley 251
electroless with Dynachen HG resist.  The electroless was 50 microinches
minimum. There was only a half percent Sulfuric after the electroless (no
antiox). We used a one tank chemical clean prior to photoresist which was
only a 140 deg F, Oakite 31 (Phosphorous Acid), with a rinse/dry (through
the old scrubber).  The Oakite was never shown to remove copper using
weight loss coupons.  The automatic electroplate line had a very tightly
controlled sulfuric/peroxide etch which removed 15-20 microinches of
copper.  (Target of 30 mircoinches of electroless into the acid coper
plater)

As to failures, We had photoresist lock-in from time to time.  Lock-in was
typical of panels which were developed on friday and plated on monday,
especially if exposed to blue light.  We had the failure mode associated
with the adhesion promoters from the Photoresist (which are left on the
copper after developing) reacting with them selves over the weekend.  I did
not / do not think this problem was related to the cleaning process prior
to resist, although the electroless surface may have encouraged the
lock-in.

As I said, this process/chemicals are 5-10 years old.  You might do better
now.  My old military captive PWB shop was outsource and closed. (as was I)
Funny how long you can remember the details.

Good Luck,


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                           George Franck
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