What surface area are the PCB traces?
For most of that kind of application I use this resin:
https://www.rapidonline.com/alh-sys...rethane-potting-compound-50ml-syringe-87-7176
but note that for best results you need the cartridge gun to ensure a perfect mix. It has a clever locking resealing system on the tubes so it keeps for a long time if you have some left over. I use it in harsh environments, >50C very high humidity and even in one case under 2.5 metres of 40C chlorinated water and after lots of experimenting it's the only resin that has survived in all installations. The underwater application is still perfect after 5 years, most epoxy resins lasted no more than a few weeks. It is very hard after about 1 hour of mixing but I always leave it 24 hours before abuse.
Brian.