I was reviewing a process specification regarding Type UR conformal coating and it contained a sentence which struck a nerve.

This particular specification stated that the thickness shall be .003"+/-.002" and .010" maximum if two coatings are applied.

I always thought there was a good reason why the coating should not exceed .005" such as CTE mismatch which might cause cracking of the coating or perhaps worse, component damage in thermal cycling.  But I haven't found any papers to that effect yet.

Naturally, any comments/experiences from this forum will be appreciated, especially if I am completely off based.

Phillip Bavaro
Senior Manufacturing Engineer, Manufacturing Engineering
L-3 Telemetry-West
9020 Balboa Ave. | San Diego, CA 92123
858-694-7874 | 858-740-8260 mobile
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