I hope this is the correct forum for the question.
I’ve just purchased one of the HMC6343 compass modules to use as a remote compass in a aircraft I’m building. Now these are seriously expensive and the environment is fairly hostile - temperature, vibration. So I assume it would make sense to pot the circuit once complete and tested. The circuit will consist of the sensor, i2c voltage convertor, i2c pullups, 3.3v linear regulator (from 5V), and a couple of capacitors. A screened 4-wire connection (SDA, SCL, GND, 5V) will then go to the central processor about 3 meters from the sensor.
Can anyone recommend the most suitable potting compound or is this not a sensible approach?
Sometimes by adding weight to the board (by potting it) you are making it worse, as you are increasing the inertia forces on the screws holding the board or the box down.
The momentum of a gram or so small SMD package is very low all by itself, and it does have a lot of solder holding it down to a comparatively thick board…
My suggestion is not to pot it. Keep the board as small and light as possible and anchor the board with 4 screws using a threadlock compound. Seal it in a suitably rated IP enclosure and forget about it.
I wouldn’t pot something for vibration or shock reasons. If vibration / shock is such a concern you may want to look at using some kind of stand-offs to mount the board that can absorb shock & vibration, but as haxby says, SMD components are pretty good anyway.
If you’re worried about moisture, there are plenty of coatings / varnishes that are designed for the task. I use a spray can type that can also be soldered through.