Wow, I haven't dealt with conformal coating for almost 50 years. I remember using a product called HumiSeal. There's spray, dip, air cure, other curing methods. Thin, thick. Hard to makw a universal statement. My impression though it was intended for humidity or condensation, not spray or submersion.My personal preference would be to put the circuit board in a NEMA4 enclosure and use conformal coating for belt and suspenders. Is there a reason like airflow you can't put it in a waterproof box?---- Original Message ----From: [email protected]: 9/9/2024 5:22:44 PMTo: [email protected]: [AFMUG] OT question for the borg
I have a motion control PCB that runs some hydraulic valves via pwm in one of my products.? We discovered that a drop of water on the right place on the PCB will turn on a MOSFET causing uncommanded movement of the system.? ? The argument around here is potting vs conformal coating.? ? The boards that were exposed to water via pressure washing operations DID have conformal coating on them but some how the water still turned on the transistors.? ? I had the P channel depletion MOSFETS pulled up with a 10K resistor.? We changed that to a 680 ohm and it made it much less likely to get turned on with water droplets.? But it is not perfect.? Needs physical protection too.? ? I am of the opinion that a good thick layer of conformal coating is just as good as potting and much less work.? Opinions? ? ?
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