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A concern about conformal coating height

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#50937

A concern about conformal coating height | 5 July, 2007

Hello Sirs:

Recently we are having an issue with environmental stress (high humidity or moisture), so we decide to apply conformal coating on our motherboard to protect via holes. According to IPC-A-610D, spec of thickness for type AR is 0.03~0.13 mm. Our problem is that it is hard to set up a good process to control the thickness during the process. If we just use brush to apply conformal coating and don't control the thickness, what would happen to our PCBA?

Thanks,

Gyver

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#50938

A concern about conformal coating height | 6 July, 2007

The coating thickness is more a property of the individual coating itself. The 0.03 - 0.13 is based on average properties of acrylics in general. It's like trying to pour 3 mils of motor oil on a table. The material will find it's own thickness.

Best way to find out what will happen to the vias is barely coat the board and overly coat it and rerun the stress test. If the material is high modulus, it might cause cracking.

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