i read all the pre-clean and clean and post scrub and scrub - whole lotta
scrubbing goin on!!!! just kidding folks.

>From the experience in the pcb field over many years i have found out that
sometimes cleaning is just a band-aid for processes which aren't maintained
properly - or just outside the optimum operating parameters.

proper neutralization after electroless copper and an anti-tarn - with forced
air drying capabilities - is adequate for dryfilm lamination and exposing.
CHECK pH OF ANTI-TARN - or get into worse trouble than when you started.


LPI applications sometimes leaves a film behind on the surface of the exposed
copper. {shops have used peroxide based tin-lead strippers in removing film -
especially when using thermal cure soldermask prior to HASL} but usually the
breakpoint on the developer is a little off ( seems no one checks these
things such as breakpoints anymore - all look for solution contact ). then
when skip occurs - it's zap that board again.

a little preventative process capability check has always paid off in the
long run - there's production and at some point - maitenance has to kick in.


regards

richard fudalewski

Atotech Canada Ltd

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