Protecting PCB from condensation?

Thread Starter

spinnaker

Joined Oct 29, 2009
7,835
I have a project that I plan to mount outdoors. It will be in a reasonably waterproof container (right now tupperware clone). But I am worried about condensation.

I want to use something off the hardware store shelf and not have to order anything special. Would a urethane spray do OK or should I go with something like this?

The advantage of the spray is if I had to get to the circuit I could.
 

thatoneguy

Joined Feb 19, 2009
6,359
I'd suggest the clear conformal coating for around $8/can. You can solder through it, and it transmits heat well.

I've used tupperware for temporary weatherproofing before and have had great results with it. Seal all I/O with silicone, and if you can, toss in a couple of those micro-bead desiccant bags that come with everything to soak up the moisture once it is sealed, then there won't be any humidity to worry about. About 1/2 cubic inch of silica-bag for each 12 cubic inches of container, more won't hurt.
 

thatoneguy

Joined Feb 19, 2009
6,359
Silicone for sealing comes in caulk tubes or large squeeze tubes.

There is also Silicone lubricant, make sure you get the sealing kind, it is easy to tell apart, the sealant is extremely thick and goes "gloop" while the lubricant is watery and goes "drip".
 

JoeFromOzarks

Joined Apr 14, 2010
95
CorrosionX is good stuff!

Due to its extraordinary dielectric properties, CorrosionX should be applied to all battery terminals, terminal strips, ignition switches, electrical connectors, circuit breakers, fuse holders, light switches, light sockets, electrical plugs, blower motors and fans to protect them from corrosion, extend their life and keep them working reliably. Although CorrosionX is inherently nonflammable, the environmentally-friendly propellant used in our aerosol cans is flammable. Please use caution when applying to electrical equipment. Before applying, make sure there is no current running though the system and that electrical motors are disconnected before applying.
:) joe
 

thatoneguy

Joined Feb 19, 2009
6,359
Off the shelf Polyurethane clear that is rated for plastic/metal has been used without problems by a few here.

I haven't personally used it, I use testors transparent candy green for the solder mask look on the bottom, and the Chemtronix conformal clear on the top side.

I think the major difference between conformal coatings specifically for electronics and others is that they are thicker, which prevents corona from high voltages arcing over components as easily. Polyurethane may have that same property, I don't have a hi-pot test lab to try the idea out in, though.
 

Wendy

Joined Mar 24, 2008
22,141
I have a recommendation I still haven't verified (dagnabit) that Krylon brand clear acrylic spray paint is good a conformal coating, just don't get it too thick.

When I do get around to it I will let you know how it works.
 

atferrari

Joined Jan 6, 2004
3,954
I do not know if you have chance to do some testing.

Valuable things that need to be packed safely and cannot be contaminated by the sealant are first bagged in ziplog-like bags. Then, the expanded polyurethane is applied.

With due care you later can break the foam and recover the goods intact.
 

bountyhunter

Joined Sep 7, 2009
2,512
I have a project that I plan to mount outdoors. It will be in a reasonably waterproof container (right now tupperware clone). But I am worried about condensation.

I want to use something off the hardware store shelf and not have to order anything special. Would a urethane spray do OK or should I go with something like this?

The advantage of the spray is if I had to get to the circuit I could.
HUMISEAL conformal coating
 
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