conformal coating best practices

[team karst]

spraying seems problematic, unless its a high volume production operation. Masking and taping. if its thin, it may even migrate thru the thru holes and run onto the gold switching area. And, you have connectors on the top side, needs masking.

Brush it on. Gain control on where it goes. BUT, if you have product water ingress, and it sits on the board, you will be on a loosing track. Gotta beat that one first.

[plebian99]

Thats not correct, maybe in the past. Most modern aftermarket conformal coatings you can solder through. Sure you might have to wipe your soldering tip a few more times for some gunk but you can solder right through it. Even the heavy thick coat epoxy type.

I use the kind that shows missed patches when exposed to a UV light so its easy to retouch the area after rework. Even when using a SMT replacement station it works out OK. You just have to very sure you have cleaned the area well before placing.

Originally Posted by goboatingnow

Once you conformal coat you’ll not be fixing it again !!

[plebian99]

My only advice when doing "brush" conformal coating is this.

Get some spare headers and plugs even spare matching sacrifice cables.

Get some Dow Corning electrical grease as an alternative.

Either plug in the spare cables and headers as sacrificial protectors or use a liberal coating of Dow Corning DC4 and coat what you dont want to be protected. It will give you hell scraping and picking to remove conformal coatings off header and other interconnect pins. Putting DC on pins is good especially in a marine environment. I always carry this stuff on my boat. Every electrical connector and connections gets a light film of this stuff.

If you can get get a conformal coating that has a dye that emits a glow when exposed to a UV light or LED UV light source it makes your life easy when patching the missed bits and also makes tracking bad connections due to messy conformal practices easy.

Good luck.

[markxengineerin]

OP wouldn’t it be better to figure out how to tightly seal the case, even if it is permanent?

I wish it were easy, but the leak is around buttons that have a silicon rubber pad on them. There is zero space to properly clamp the button together, that's probably why they resorted to odd plastic posts that break.

I have not done the deed yet, but will be looking out for connectors and switches, as suggested.

[team karst]

Looks like sun got to the display as well. Is there a source for those? If not, maybe time to punt.