Product for Protecting Circuit Boards from Water?

Thread Starter

Art Duino

Joined Nov 30, 2017
30
I have to replace a moonroof motor in a Ford Explorer. My understanding is that when water gets to these things (nearly inevitable because of the car's design), the circuit boards corrode quickly and go bad even though the motors are otherwise fine. The circuit boards are not protected by film or anything.

Before I install the new motor, I want to know if there is a product out there for coating circuit boards to protect them from water. It looks like Ford makes a lot of money from selling new motors, so they don't have much motivation to protect their products.
 

SamR

Joined Mar 19, 2019
2,419
For saltwater marine submersion I use Starbrite Liquid Electrical Tape. Comes in a 4oz can with an applicator brush under the screw-off lid. Available in black or white. Good stuff. It's basically a liquid rubber.
 

SamR

Joined Mar 19, 2019
2,419
I just learned something new. In all my years I never heard of Conformal Coating. I just put it on my to order list. I've been using liquid tape for a few decades and there are 2 properties that the conformal coating stuff has that it doesn't, see-through visibility and don't have to remove it to solder. Pretty neat stuff! Ain't the internet just grand, Actually a third, high temp capability.
 

Janis59

Joined Aug 21, 2017
1,205
MaxHead - thanks for good term. I didnt knew how it is at English.
I have checked a many materials - very good are given by China coloured pcb protective cups. Normally it are elaborated on pcb by small press and exponated by uv, but when the aim is to cover all, the brush may work. I tried the thick old-school transparent wood lack (glyphtal resin) - very good results, but it is taken off from production, and modern lacks are too thin.I tried an epoxy, it give catastrophic theram walk in temperature, thus the pcb patches may become disrupted. Probably pcb may be diluted with some 5 or 10% of good elastant like dibutilftalate, but have no experience. Checked with PVA but not stable enough. Tried silicones and acryls - gives short for eternal between all patches - that is effect of acid hardener. So, palette is not so wide as may like.
 

Janis59

Joined Aug 21, 2017
1,205
P.S. In automotive as well at transmitter business exists one excellent material - self-curing rubber sheets. Just wrap in, and forget.
 

Tonyr1084

Joined Sep 24, 2015
4,927
I just had a smoke detector fail. It failed because of a poor solder joint. The entire board is coated in wax. WAX! Can you imagine what that will do in a fire?

Anyway, yes, conformal coatings have been used on electronics for many years. Some are easy to clean off electronics to facilitate repairs, others are much more robust. I have a failed control board out of my dishwasher. Definitely a humid environment. The coating on that board is very tough. Extremely difficult to do any solder work on the board; which I have no intention of repairing. I will be removing relays and some high power MOSFET's, maybe a connector or two, but because of the hard coating it will be very difficult. As for the reason for the failure - it's likely due to the corruption of the programming in the microprocessor.
 

SamR

Joined Mar 19, 2019
2,419
I've encountered the wax dipped method and just shook my head in wonder. Might be alright for long term storage but what happens when it heats up under load?
 

narkeleptk

Joined Mar 11, 2019
468
I use mg chemicals silicone or acrylic conformal coating on Automotive modules I like the silicone better but the acrylic is cheaper so it just depends on how much I need to use and what's already on there.

There is also the stuff at Home Depot called scotchkote, this stuff works great in modules that take heavy weathering and are in unsealed cases
 
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