Waterproofing the Controller Silicone Spray

[broloch]

Hi Gentlemen,
How were you able to waterproof your controller? Is it best to use a silicone spray over the circuit board?

Is it okay to completely seal and make the controller air tight with a type of silicone sealant? Bathroom/bathtub Silicone sealant? This is like caulking and is mildew resistant. Is an airtight controller bad? Is it bad to make the controller sealed? I have a part where I can insert a key into the controller, is it bad if I spray silicone spray into the key hole?

 

[broloch]

I mean something like this to spray over the components, the circuit board, the internal wires, the FETS, the Caps, etc.
And the second item, the sealant to seal all the cracks and crevices of the controller, and the screws. What do you think?
Will it cause problems with heating -i.e. make it difficult to dissipate heat?

 

[Zoot Katz]

I'm no expert but after reading numerous articles and threads I opened up the controller, bought a bottle of conformal coating and applied it to both sides of the board. The hot glue holding the capacitors was also suspect so I removed it and used non-corrosive RTV silicone from the electronics store instead of taking a chance with bathtub caulking. While I was in there I also upgraded the insulators on the screws holding the FETs to the heat sink.
Hot glue sealing around the wires' exit points is controversial. The wires should exit from the bottom and form a drip loop so water can't seep in.
The buttons and switches are hard to seal effectively so the theory is that by not sealing around the wires any water inside will be able to drain out.

Another bit of advice I followed is to be sure all the solvents have evaporated off before closing the controller.
That's one reason I'd not be spraying silicone willy-nilly into the box. Anyway, it won't get far just squirting through the key slot.

There was expert guidance every step of the way easily found in the archives.
Search for "waterproofing controller" without the quotes and follow the links.

 

[johnrobholmes]

You need silicon that is called conformal coating. It has to stick and dry.

 

[Zoot Katz]

You need silicon that is called conformal coating. It has to stick and dry.

The stuff I bought is urethane based. It was brushed on after cleaning the board with alcohol.
A respected source suggested clear nail-polish as a cheaper alternative.

 

[v_tach]

Don't discount the use of the regular silicone spray on the outside of components and wires. Works very well for modest moisture and corrosion protection. Should be repeated every few weeks. It'll keep moisture from creeping between the edges of a controller enclosure and through grommeted or other small openings. I'll also spray connectors.

I've been an avid boater for many years and use generous amounts of silicone spray under all of my boat's engine covers on electrical components and behind the console on the fuse panel and any other accessible electrical related components. It works amazing well, its cheap, and easy to do. Hard to find a more unforgiving environment on electrical components than marine use.

I'm not talking about protection from a deluge but I believe its a good compliment to other efforts.