I whole heartedly agree. Inspect the fabricator's
cleaning and scrubbing techniques
prior to mask application. That is where the
trouble lies. Mask goes on like an
adhesive and like an adhesive it needs a clean
surface and, if possible, some
texture to adhere to.
CR
Dave: The obvious answer is that the soldermask is not properly
bonded to
the board. The adhesive strength of the CM8 to the soldermask is
nowhere
near the bond strength of the mask to board. My first guess would
be there
is some type of surface contamination between to board and
soldermask
causing this.
A couple of questions to better answer your
question:
1. What type of soldermask is it?
2. Is it coming off the
laminate, immersion silver or both?
3. If you apply the CM8, allow to cure
and peel off without wavesolder does
the same thing happen?
4. Is it
possible that screw/nut/heatsink are fracturing the mask in some
fashion
causing it to lift?
Regards
Michael Barmuta
Staff
Engineer
Fluke Corp.
Everett
WA
425-446-6076
-----Original
Message-----
From: Dave Chapman
[mailto:[log in to unmask]]
Sent: Friday, August 08, 2003 6:59
AM
To: [log in to unmask]
Subject:
Re: [TN] The attack of the Peelable Mask
-----Original
Message-----
From: Dave Chapman
To: [log in to unmask]
Subject:
[TN] Peelable Solder Mask
I am putting Chemtronics
Chemask CM8 on a screw and nut securing a heatsink
and when I peel it off
after wave solder the board solder mask is coming off
as well. The boards
are Immersion Silver Finished. We have used the Chemask
for hundreds of
thousands of PCB's without this issue. What could be wrong?
Dave
Chapman
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