JF, I've been facing the same problem.  Called Humiseal, Ed there told me the ASTM test isn't much good since you need a big area to work with, not available on PC boards.  He said he makes an X with an exacto knife and tries to lift the points of the coating thereby formed.  As a quality person, I'd like to have some good data to analyze.  It looks like the only way to get hard data is to run a lot of boards for whatever coatings your trying and do some counting of blisters, peeled spots, etc.  Not easy...Lou Hart

----------
From:   Jean-Francois Bissonnette[SMTP:[log in to unmask]]
Sent:   Friday, December 03, 1999 10:26 AM
To:     [log in to unmask]
Subject:        [TN] Conformal coating pelling off

Hi!

We use silicon conformal coating on some boards and some of these
show a lack of adhesion of the coating.  It peels off very easily
with gently scratched.  I also heard of some peeling test that could
be done, can it be done with any kink of tape?  The same coating on
the other boards wont peel if I try to scratch it off.

Can anyone shed some light on this?  I tought that it would be a
cleaning problem but the supplier says that they do clean it.  Can
the board material be the source of that problem?

Thank You!

JF

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