I'm designing a PCB that will be installed in an IP65 plastic case. The device will be installed in multiple scenarios and regions (indoors, outdoors, high/lo temperatures, high/lo humidity etc). The device is a BLE SoC with a relay and is is directly connected to the mains (the device has a 3W power supply on the PCB). The device will be installed in a fixed place and should last for at leat 10 years without maintenance.
I would like to know if it is necessary to apply conformal coating, potting or any type of resin to protect the device from possible condensation or, as the PCB is inside a plastic IP65 case, it is not necessary.
In case it is necessary, which conformal coating, potting or resin would be suitable for this application?