Are the air bubbles along component edges or open areas? It might be that
you are moving the board in/out of the material too fast.  I know from a
past project we needed to allow extra time during the dip prior to removal
for the air bubble to release on SOT package devices. 

Kat

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ken Bloomquist
Sent: Monday, June 02, 2008 11:27 AM
To: [log in to unmask]
Subject: [TN] Tiny Bubbles

Happy Monday All,

This has nothing to do with the ISS or Lawrence Welk :-)

On occasion we get tiny bubbles in our moisture cure, polyurethane conformal
coating. We know that if the humidity is high (seldom happens here in
Western Washington) and you get the coating on a little thick the bubbles
will form. I'm sure the coating skins over really fast in high humidity and
then all those little volatiles can't get out creating tiny bubbles.

My question is, are there any methods for removing these little bubbles once
the coating is cured? Generally they are not bad enough to need rework but
on occasion there are just too many to ignore.

Thanks as usual for any help,

KennyB

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