Electronic – What’s the best way to protect a board from corrosion in a hot/moist environment


Some of my projects need to live outside for long periods. Sometimes, moisture gets into the enclosures. That means that a circuit board might be sitting around in contact with water for hours on end at upwards of 100F.

I've noticed that solder joints can start to corrode, and recently moisture made it under the solder mask on a board and actually ate through one of the traces, breaking the circuit. I know the ideal answer is to make a perfectly sealed enclosure, but I'd like to toughen the boards up a bit as a second level of defense.

Can anyone suggest some tips and tricks for making PCBs more corrosion resistant? Does scrubbing off excess flux help? What about spray acrylic sealant? Special solder?

Best Answer

Sounds like your boards are in a very tough environment, but anyway, it is common practise (and an accepted industry standard) to use so-called Conformal Coating.

I know from experience at one of my previous companies that it does help.

Material varies, but the article in the above link explains a lot and internet searches for "Conformal Coating" will yield many products. I have used brushes to apply the coating after reworking PCBs, but in volume production, spray or dipping are used.