Good morning -

It sounds as if the coating is forming a thin web around the perimeter of your
module during the dipping process, then creating bubbles when the trapped air
underneath expands during cure.  The solutions are normally to vent the area
so pressure cannot develop, or apply a slight vacuum during or immediately
after dipping to break this film of material prior to cure.

Since you are applying a conformal coating, it suggests that your hardware is
slated for a severe environment.  Have you considered that the area under the
module body might be remaining uncoated and pose problems from the standpoint
of retained process residues, etc.?

Regards - Kelly

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