Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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Conformal Coating Coverage



Conformal Coating Coverage | 30 January, 2003

Can anyone tell me what parts on the pwb should be protected by the conformal coating, and what parts can be free of the coating (such as the areas without components, traces, brides lands)? we were follow MIL standard 2000 and IPC-A-610 class 3. Thanks you.

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Conformal Coating Coverage | 30 January, 2003

NASA-STD-8739.1 , Workmanship Standard for Staking and Conformal Coating of Printed Wiring Boards and Electronic Assemblies, says words to the effect of : 10.1 Purpose Conformal coatings are intended to provide electrical insulation and environmental protection thus minimizing the performance degradation to electronic PWA�s by humidity, handling, debris, and contamination.

What is the purpose of your coating?

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Conformal Coating Coverage | 30 January, 2003

The easy part is to determine which parts should be coated. The harder part is making sure the parts that should not be coated do not get coated.

I don't even want to think about the amount of labor and materials I've lost due to conformal coat getting into places where it should not be. Work with your coating supplier to determine the best materials to use when masking your boards. For instance, I recently had an acrylic conformal coat material soak through 3 layers of a "painter's masking tape". Lucky for me, we were able to replace the $80 connector without damaging the $900 PWB it was soldered to.

Every conformal coat material I've used was clear, but had a UV tracer in it so the coating would glow under black light. That means you need a black light to make the coating glow so you can inspect it.

Mike F

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