K-OS

Has anyone done this? Is it bad for the electronics? I want do dip my receiver and servos PCB to make them waterproof.

Edwin

My Feedback: (2)

Will be interested in hearing the results on this one. At work, I've used goop but that was on small cable assemblies and mostly for strain relief. Never tried it on electric components. It stays somewhat more plyable than epoxy. You might get refused service if you need a repair done.
Edwin

airbusdrvr

I was thinking the epoxy would certainly eliminate any further service for the item.

bobferguson

You could epoxy the receiver but I don't think you would ever service it. Also have to be careful not to break the antenna off. As for the servos I don't you could epoxy the pcb and still get in it's case and this would still allow water to get in the motor.

K-OS

As far as servicing the electronics, I think everyone with experience knows that getting through epoxy once hardened is impossible. This problem is a major concern mostly for those high-end receivers (several channel, spektrum, PCM, etc.).

Another solution would be the GOOP way, but GOOP comes off sooner or later.

As for seating the PCB back into the casing, even a small layer of epoxy is sufficient to completely waterproof the electronics (MINUS the motor, unfortunately). Motors can be cleaned, and are not really affected by water. Electronics on the other hand short out and are rendered useless.

Gonna give it a try folks!

redfox435cat

I wouldn't do it

get a plastic bag and use RTV silicon gasket. Put the receiver hooked up in the bag with all the wires hanging at. Put a couple water absorbent pellet bags inside the bag with the receiver, this will suck up any condensation in the future. They usually come with other electronic gadgets like camera and lenses. fill the open end with the RTV and rubber band the outside. totally waterproof, and serviceable if need be.



the servos.

put a small dab or rtv around both top and bottom or the casings and both ends of the screw holes and a good dab around the wiring grommet. When you rtv the plastic case make sure you apply the rtv in such a way the goo oozes outward, don't get any on the gears. I've done this on all three of my sea planes and all are still flying without problems 4 yrs running. For the turning shaft use vegetable grease used for cooking equipment. works best with ball bearing servos. Doing this I've submerge the servo in water and they works just fine.

Edwin

My Feedback: (2)

You might be thinking of silicon adhesive. Goop doesnt come off. I glue my airtanks in with goop and they're still stuck after a bad crash.
Edwin

4*60

My Feedback: (41)

Would be the end of heat dissipation.

ByLoudDesign

If you pot it and something goes wrong there is no warranty! If you have that bad of conditions where you fly, or if it is a sea plane or anphibianget a good quality plastic refrig container to suit the size of the stuff, put a hole in it just large enough to allow shoving the leads into it. Do not have the leads come out from the devices in side unless they are unpluggable or a screw clamp connection, this way everything can be removed if necessary. Now with all leads stuffed inside and connectedseal up the hole with bathtub silicone! Or if you just want to make sure you have a little insurance against the rain, stuff in in a good grade ziplock bag and make sure when you stuff it in the plane the wires and the zipped opening are pointed down!

bobferguson

I'll keep this in mind if I ever get around to building a float plane. Sounds like a good way to me.

GBR2

My Feedback: (1)

Why not just dip them in Corrosion X? That will render electronics waterproof with essentially no weight gain.

3D_Junkie

This is common in the aerospace industry, it is called potting. With just straight epoxy, you would lose all cooling and that could be detrimental. It may not seem like a problem, but most of our electronics need some sort of cooling mechanism (evne ambient air) or they will overheat.

The other thing I would be worried about with regular epoxy is the adhesion to the PCB. If the epoxy adhears to the components and not the PCB you could be making the failure mode worse. I.E. you have a much larger mass that is trying to pull the components out of the board.

If you are serious about potting the components, do a google seach and get the right materials. I would look for resigns that have some heat dissipation characteristics.

Potting your components will viod your warrenty and totally destroy your resale value. If that is not a concern go for it.

CloudSkipper

Just another idea (possibly very silly): how about that expanding foam you put between window frames and such?

I heard of a guy incasing a computer motherboard and all peripherals in foam instead of buying a computer case (he did it for kicks). Computer worked, but it ran pretty hot Needless to say that's a major fire hazard though.

Back to R/C RX's... because of the nature of the foam, you'd probably want to practice on a dumby RX to see how you can get it to work without using too much foam (so the volume does not get out of hand). It would absorb vibration also.

tkilwein

There is commercial grade conformal coating designed for electronic components.
Do a search for electronic conformal coating products.
Once you do this your warranty is VOID!
You can repair the parts with the conformal coating removed, there is a remover for some brands and types used.
Make sure you get one with the right properties, remember you have high freq RF signals. IF unsure don't do.

bruce88123

There is a product called Humiseal 1b31. It can be sprayed, brushed or dipped onto the products.
http://www.ellsworth.com/display/pro...6&Tab=Products
We use this where I work. It also comes off fairly easy for servicing/repair. Just don't over do it. Keeps moisture away and corrosion off boards.

Julez

Do not use Epoxy!
It shrinks a little during hardening and over time. In the company I worked, the electronics guys told me about a company that did it with the intention the make PCBs for CNC mills more durable. After some years, one board after the other was failing. Finally, they found out that due to the epoxy shrinking the components were pulled right from the board. So, do not use epoxy.
The substance mentioned in the posting above seems to be far superior for this purpose.

GlowFlyer

I second what Julez says. I was responsible for epoxy potting many products in years past and to begin with they regularly suffered early failures from epoxy shrinkage. It didn't so much pull components off the board as to cause minute fractures in the component leg seals causing gradual semiconductor degradation, or in some case fracturing rigid components like some ceramic devices. The cure was to first conformal coat with a rubbery coating followed by the epoxy potting.
Most of the conformal coatings at the time were moisture repellent but slightly moisture permeable. Depending on your needs I would suggest the ideas with ziplok bags and sealant would be best. Don't use the commonly available silicone sealants based on acetic acid curing agents as the vapour will cause corrosion of copper traces on pcbs.
--
Steve

K-OS

Wow!

You know epoxy shrinkage makes sense. I would say it takes several weeks for it to completely dry and I have seen some epoxies crack (aerospace epoxies don't seem to suffer from this).

I'm still not too crazy about these gasket sealers, my experience tells me over time it comes away from the surface if there is no pressure on it

Gonna check out Humiseal, that is purpose built for sealing electronics. From what I understand it is simply an acrylic "paint" made for electronics.

Thanks for the abundant information!

bruce88123

It's more of a "coating" than a "paint". I've been using the stuff for over 30 years on full scale avionics. It's really good stuff. There are some newer items in the field but the Humiseal remains better IMO because it can be worked through for repairs. Can't do it any more due to EPA regs but I used to keep an ultrasonic bath on the bench with Freon TF in it. Drop the board in it for about 5 minutes and it comes out cleaned. Do the repairs and recoat. Good as new.

dirtybird

My Feedback: (5)

IMO its a dumb idea. My only question is why? Your recerver will not work under water if its waterproof. Otherwise the case should protect it.

bruce88123

Maybe he is worried about high humidity. I guess I'll stop using it on my avionics too. After all, they're airplanes and not submarines. Oh wait, they do fly through rain and the pilots do spill things into them from time to time. So I guess I'll just ignore you.

misasi

call me crazy but a balloon works perfectly on my 1/10 truck... ive even hosed it off with no problems.

dirtybird

My Feedback: (5)

I lived in Seattle for 25 years. Thats about as high humidity as you can get. Nobody I knew dipped their receiver in epoxy.
If the receiver has tunable IF cans you will never be able to retune it.
I once had an airplane land in a sewage treatment sprinkler area. That water is corrosive. I just hosed it off with fresh water and it never hurt it a bit.
I bought a surplus Tektronix oscilloscope that had been left out in the rain for several months. I called Tektronix and asked how to clean it. They said to take it to a car wash and carefully wash away all of the dirt keeping the water out of the transformers if possible and put it in the trunk of your car on a hot day to bake the water out. It was summer.
Most of it worked afterwards except the delayed sweep.
If you are a pilot and fly thru rain I hope you buy your avionics in a waterproof box. What can I say about spilling? I hope you are not my pilot.
When I worked in the military avionics dept of Boeing we had to make the box waterproof,dust proof, radiation proof and it had to survive a drop from a 10 ft table and still work.
Our electronics are not made to a mil spec ,but most of the people that make them have had experience of working there, and know what works.

GBR2

My Feedback: (1)

Corrosion X

Flypaper 2

Many of the rcvrs and servos back in the 60s and early 70s had potting compound on them but it was mostly to fight vibration. Didn't have ICs back then.