Waterproofing a circuit board help!

[Burtonrider10022]

I am looking for an epoxy/sealant that I can use to seal up an LED light. It's going to be used as a reverse light on my SUV, but I go through the car wash a couple times a week, and I'm confident that the pressure washers will kill it.

It IS intended for outdoor use on a vehicle. Here is the actual light: http://www.vleds.com/bulb-type/reve...back-up-light-license-plate-frame-chrome.html

Others around the web have said that theirs has died from water damage, and the LED board is not well potted at all.



My first thought is liquid electrical tape I am not willing to spend much more than about $10-$15 on supplies though...

Any suggestions on a cheap epoxy or lacquer that is safe for electronics? It doesn't necessarily need to be clear, either, so black would work.

 

[Falcon67]

Why not spray on undercoating or bedliner.

 

[ForceFed70]

There are special compounds for just this purpose. In essence: You smother the board in silicone or epoxy. Also refered to as potting.

HOWEVER: Be very careful when doing this. You can easily cause overheating problems.

IMO: Sealing up the housing may help, but temp changes (such is submersing in water, or even getting it sprayed by cold water from a puddle) cause pressure differences in the housing. This creates a vacum and will literally **** water into the housing. A housing that is now sealed and won't let the water out. Best is to focus on potting the board.

 

[bullnerd]

Couple times a week?! Damn your gonna wash the paint off!

 

[nehog]

Epoxy is acceptable. Any conformal coating will work. I would not use bed liner, or something similar.

 

[Burtonrider10022]

Bed liner is actually an interesting suggestion. I don't think it will work though because the circuit board has exposed electrical contacts, and therefore any coating will need to be non-conductive to avoid shooting shorting out.

As for the housing I'm going to seal that as well but this issue is that the circuit board is actually on the back of the frame. Only the LED's are inside the housing, which is why I need to pot it. This is also why potting and over heating should be completely independent from each other. Not too mention the fact that I'm only going yo be backing up for a few seconds at a time..

And regarding the washing, I actually just washed it right now. Lol. I have unlimited washes at my local wash and just pay a monthly flat rate. One you factor in the $0.10/gal discount I practically break even.

 

[MFolks]

The electronics industries have used this method of conformal coating for many years:
http://www.humiseal.com/

 

[Burtonrider10022]

The electronics industries have used this method of conformal coating for many years:
http://www.humiseal.com/

Yeah, that is exactly what I was looking for, except it's astronomically expensive....

http://www.kranderson.com/shop/Humiseal

 

[retrobuilder]

http://www.mouser.com/ProductDetail...GAEpiMZZMvJqaFk9BIiv%2bBRywvBA9v9PW3VulxT1CA=

Use an aerosol acrylic conformal coating available at Mouser, Digikey, Mcmaster Carr..
cheaper and easier than high tech parylene coatings used on tablets and phones.

Or if a deep cavity use a two part epoxy potting compound.

 

[thatvan]

http://www.mouser.com/ProductDetail...GAEpiMZZMvJqaFk9BIiv%2bBRywvBA9v9PW3VulxT1CA=

Use an aerosol acrylic conformal coating available at Mouser, Digikey, Mcmaster Carr..
cheaper and easier than high tech parylene coatings used on tablets and phones.

Thats what I use. Never had an issue.

 

[Burtonrider10022]

So I grabbed some liquid electrical tape today and gave it a shot. It's close to what I was looking for, but it just doesn't seem like it's going to hold up long-term. For now though, the board is just going to get a liberal application of it. Until I can find an inexpensive epoxy this should work ok.

As for that glitter fabric stuff, after checking it out at Wal-Mart, I'm nit sure if you were just messing with me...

 

[rlitman]

Until I can find an inexpensive epoxy this should work ok.

Epoxy IS less expensive than liquid electrical tape. You can buy two little bottles and mix, but it sounds like the double syringe will be enough for your needs. You're not buying West System by the gallon for this.

If you want something more paint like, consider gloss water-based spar urethane spray.

DO NOT USE SILICONE unless you really know what sort you have.
Many silicones release acid when curing, and will completely destroy electronics.

 

[Burtonrider10022]

The double syringes of epoxy were about the exact same price as the liquid tape. The only reason I went with the tape was because NONE of the epoxies I find at auto zone, micro center, target, off Walmart said that they were either safe for electronics and/or non-conductive.

I feel like I need to clarify, you don't need to talk me into using epoxy, it's what I'm hoping to use. I just can't find one that looks correct (for the right price, as well)

 

[jhelrey]

Wrap it in electrical tape afterwards and you should really be set...

 

[James-W]

Would it be possible to move the circuit board, put it inside of a plastic box and seal it up? Then you run wires from the plastic box to the light. If you seal the box where the wires are with a sealant I would think everything would be pretty much waterproof. It's just a thought and maybe it won't work in your situation, but I thought I would mention it anyway.

 

[77thor]

Home Depot carries "spray-on" rubberized electrical tape.

 

[rlitman]

NONE of the epoxies I find at auto zone, micro center, target, off Walmart said that they were either safe for electronics and/or non-conductive.

If it is translucent, it will be fine. The liquid epoxies are non-conductive unless they have a filler that will make them thicker and opaque.

 

[Burtonrider10022]

If it is translucent, it will be fine. The liquid epoxies are non-conductive unless they have a filler that will make them thicker and opaque.

Hmm... I haven't heard this before... I wonder which would be non-noncorrosive... I'd imagine any that list metal or copper under recommended uses.

 

[rlitman]

Corrosive silicone, yes, maybe. Hardware store 5 minute epoxy, no.

Just plain translucent 5 minute two part epoxy. Not copper pipe sealing epoxy. Not plumbers epoxy. Not underwater epoxy. Not plastic bonding epoxy. Not any other specialty blend. Just plain yogurt, I mean epoxy.

 

[darkk]

That light setup is already waterproof...it is made for outside auto useage. If in doubt, contact the company you bought it from, save your money.

 

[Burtonrider10022]

That light setup is already waterproof...it is made for outside auto useage. If in doubt, contact the company you bought it from, save your money.

As stated in the original post, the OEM waterproofing is extremely sub-par and many owners have had failures because of it, most after the warranty expires. I figured $4-$5 with of epoxy would be considered saving my money over throwing out the $60 item.

 

[Burtonrider10022]

Corrosive silicone, yes, maybe. Hardware store 5 minute epoxy, no.

Just plain translucent 5 minute two part epoxy. Not copper pipe sealing epoxy. Not plumbers epoxy. Not underwater epoxy. Not plastic bonding epoxy. Not any other specialty blend. Just plain yogurt, I mean epoxy.

I'm going to return something at Walmart in the morning, will any of THESE work? Otherwise I can make the journey over to Home Depot if really needed.