Waterproofing is essential to prolong the life of electronics in an FPV drone, and conformal coating is the most common method to achieve this. By protecting your components from moisture and chemical damage, you can ensure your drone can handle flying in extreme conditions.
Table of Contents
What is Conformal Coating?
Conformal coating is a thin, protective film that adheres to the contours of a printed circuit board (PCB). This coating creates a layer of insulation on the components and solder joints on the PCB, preventing potential electrical shorts.
Why Conformal Coat?
The goal of conformal coating a quad is to make it water resistant.
Even if you don’t plan to fly your drone over water or in rainy or snowy conditions, waterproofing your drone electronics is still beneficial. Conformal coating serves as a preventive measure against humidity and moisture from wet grass or leaves that might come in contact with the drone during landing or crashing. By protecting against these potential hazards, conformal coating helps prevent electrical shorts on exposed solder joints and prolongs the life of your drone’s electronics.
Types of Waterproofing
There are two popular solutions for waterproofing drone electronics: silicone and acrylic.
The primary advantage of acrylic coating is its easy removability. You can quickly burn through the coating with a soldering iron. However, the lack of durability is also its downside, because many components in a quadcopter, such as video transmitters, can generate substantial heat which might be enough to melt through acrylic coating.
Therefore silicone coating is the preferred choice for quadcopters or RC models in general, as it can withstand higher temperatures than acrylic.
Where to Buy Silicone Conformal Coating?
I recommend using MG Chemicals Silicone Conformal Coating for waterproofing your FPV drone electronics. Although there are other alternatives, this product has proven its effectiveness and is considered the gold standard in the hobby.
You can purchase MG Chemicals Silicone Conformal Coating 422C on Amazon: https://amzn.to/3nkSWyb. Note that the label on the new version has been updated.
There are two versions available: one without UV indicator and the other with the indicator. The one with UV indicator fluoresces under UV light, making it extremely convenient for verifying complete coverage of the coating. This feature is highly recommended!
To verify the coating coverage, you can purchase an inexpensive UV light torch on Amazon: https://amzn.to/3vbOR2b.
The left board is NOT conformal coated, while the right board is coated – the glow under UV light indicates coverage.
When it comes to conformal coating for FPV drone electronics, it doesn’t take much. A 55ml bottle, available on Amazon for around US$20, should be enough for several dozen quads and will last for years for an average pilot. The bottle comes with a nail polish-type brush attached to the cap for easy application.
Avoid the spray version, as it can get on components you don’t want to coat, such as connectors and buttons, which may cause them to malfunction. The spray also makes it difficult to achieve even coverage due to the lack of precision. Applying the coating with a brush is the best method.
Lastly, I recommend getting some isopropyl alcohol (rubbing alcohol) for cleaning your electronics before applying the coating and for removing the coating if necessary.
- Amazon: https://amzn.to/3gBL6yW
Preparation
It’s best to apply conformal coating on a quad you have already built, as the coating on solder pads can make soldering more difficult later. If you plan to waterproof a new quad, finish building it first and test-fly it to ensure all components are functioning correctly. Only then should you apply the conformal coating. Remember to reapply the coating on any solder joint if you redo the soldering on the quad.
For older quads, consider removing any tapes and heat shrinks covering the PCBs. Clean the electronics thoroughly to remove any dirt before applying conformal coating. An old toothbrush and isopropyl alcohol work well for this.
Applying Silicone Conformal Coating on PCB
Warning: Conformal coating can be a carcinogen, so avoid inhaling its fumes and ensure good ventilation when applying it.
When applying silicone conformal coating to your PCB, focus on covering exposed metal surfaces, particularly microchip pins, solder pads, solder joints, and any areas that might conduct electricity when wet. However, be cautious not to cover certain componetns, such as:
- Flight controller: boot button, USB port, barometer
- FPV camera: image sensor
- VTX: channel button
- RX: bind button
Apply the conformal coating like nail polish, brushing it on evenly to create a shiny, protective layer.
To check for complete coverage, use a UV torch. The coating contains a UV tracer that fluoresces when exposed to UV light, making it easy to see where it’s applied and if any areas need additional coating. Ensure the coated areas have a consistent, even glow.
Allow the conformal coating to dry for about 30 minutes, but consider letting it dry overnight just to be safe before flying your drone. Typically, one layer is sufficient, but if you feel more coverage is needed or if you missed some spots, you can apply another coat for better protection.
How to Remove Silicone Coating?
If you accidentally covered solder pads or need to remove silicone conformal coating for any reason, you can use isopropyl alcohol and a brush (or cotton swap). The coating can also be burnt away with a hot soldering iron.
Some flight controllers (FC) and electronic speed controllers (ESC) come pre-coated with silicone. However, the spray coating may be uneven and miss certain spots.
To remove the coating:
- Take a cotton bud and dip it in isopropyl alcohol.
- Gently rub the alcohol-soaked cotton bud on the PCB where you want to remove the coating.
- It should only take a few rubs to remove a thin layer of coating.
If you need to remove all the coating on a PCB, follow these steps:
- Submerge the entire board in isopropyl alcohol.
- Gently scrub the board with a soft toothbrush to dissolve the coating.
- Allow the board to dry completely before using it again.
Pro Tips
To prevent damage to connectors, plug in all connectors before applying the coating. This ensures that the coating doesn’t ruin the contact inside the header/connector.
Keep in mind that silicone coating can be burnt away with a soldering iron. If you re-solder something, remember to reapply the conformal coating to the reworked area.
To fill small gaps, such as those between capacitors and resistors, try blowing the coating with compressed air (but not too close, or you’ll make a mess).
Preventing the Cap from Getting Stuck
Before closing the conformal coating bottle, clean the rim with a paper towel to remove any residue. The silicone coating acts like glue, and the cap can get stuck if there’s coating left on the rim.
If you can’t remove the cap, try these tips:
- Gently heat the cap with a hair dryer or heat gun (on low heat so it doesn’t melt the plastic).
- Tap the edge of the cap with a butter knife or against a bench to break the hardened coating around the edge.
Flying FPV Drone in the Rain
Remember, while flying an FPV drone in the rain can be an exciting challenge, it’s not something to take lightly. Always ensure you’ve taken all necessary precautions before attempting it. Apart from conformal coating your drone completely, there are a few other tips you can follow if you decide to fly in the rain.
- Visibility Problems: Be aware of potential vision issues due to water droplets on the camera lens or goggles fogging up.
- Thrust Reduction: Rain can decrease the lift produced by your propellers, you may need to use greater throttle than usual. You may want to consider using larger or higher pitch propellers.
- Transmission and Signal Loss: Keep in mind that the rain can cause signal loss or interference, affecting your video feed and control signals. Try to stay as close as possible to the drone to mitigate these issues.
- Control Difficulties: Be prepared for the possibility of harder control mid-flight due to strong wind gusts.
- Post-Flight Maintenance: After flying, it’s crucial to dry off your drone as soon as possible. Leaving it wet could cause corrosion over time.
What to Do If You Crash Into Water?
If your drone crashes into water, follow these steps:
- Remove the drone from the water ASAP, and immediately disconnect the battery.
- Rinse the drone with distilled water to remove minerals. Brushing with isopropyl alcohol is even better (NOT the motors just the electronics).
- Allow the drone to dry completely. Using rice is not practical; instead, use a fan and let it dry for at least a day.
Conclusion
Waterproofing your FPV drone electronics with silicone conformal coating is essential for extending their lifespan and protecting them from moisture-related damage. By following the tips and procedures outlined in this tutorial, you can ensure your drone stays functional and ready for your next adventure. Happy flying.
Edit History
- Feb 2019 – tutorial created
- May 2023 – updated product links, added a few more pictures for instructions
23 comments
hi
is it possible to damage gyro when coating with 422C? I’ve applied coating, ensured that it was dry, and after assembling quad I have no_gyro(mpu6000 installed on FC) issues in betaflight. It works for several minutes, but after calibrating and some basic maintenance gyro stops working.
To increase the chance of recovery I advise rinsing the electronics, see the motors and even the servos (it may even be necessary to dismantle them, there are electronics in them) with demineralized or distilled water (p .eg water for iron) in order to remove residues such as salt, metal particles etc. simply soak them and rub with a fine-haired brush and then rinse them in a tank of also demineralized or distilled water. After wiping the equipment you can dry everything except the battery in a hot air oven at 80° for ~15 minutes. It is imperative to do this before attempting to reconnect the battery.
Just a quick comment about crashing into water. You need to unplug the battery prior to getting it out of the water, it greatly increases the chance of saving your electronics.
Would you use it on the dji air 03 unit with the breather vents?
If you fly in humid or wet condition, then probably a good idea.
Thanks very informative and educational I’m new to the hobby. My one stop information library
Do i have to coat also my caddx vista? or just antenna port and outcoming wiring only? i am not planning fly in rainy days, just in fog , snow and my crash in snow, so not sure about vista now
I juste realized…my coating IS in polyuréthane… Doens’nt do well wirh water i think…
Hey Oscar, thanks for the information. I will be running the vista nebula pro and those things (according to online and forum reviews) generate lots of heat. Have you seen any issues with heat buildup after applying this product?
Thanks,
Phil
just make sure the large chips are not covered with, maybe it’s okay, the heat is mainly originated from those chips. I have not tried it on the Vista though so I can’t comment if it’s going to work 100%.
Hello. I was wondering if anyone’s conformal coated quad motors. Is it ok to do so?
Drone motors are waterproof already. My float plane recovery boat ran one fully submerged.
Is it possible to waterproof Caddx Vista unit?
is it ok to just dip a an esc in the bottle rather than applying with a brush. Id rather not try to pull of the heatsink.
My Kakute f7 has the SD card slot onboard – any tips for getting around that? I don’t ever intend to use an SD with it, so should I just brush the silicon on normally?
if you don’t use it, then just brush over it :)
Great tut! Thanks!
Ive used Si conformal coating a few times with mixed results. One thing that does work for me is brushing on a coating of CorrosionX on all connections (plugs). Its messy, but it still allows the connection. Also I had some problem with my gps module after I coated it (would not lock on). I cleared the coating from the metal spot in the middle of the top (antenna?) and it got a lock after that. Anecdotal, but it worked for me.
I still have a couple of questions that maybe you could help me with:
1) Do esc require additional protection? That seems to be a particularly water sensitive component and the only thing that smoked after water exposure.
2) What can you do for barometers? Anything?
3) Any tips for coating the TX?
Thanks!!
Wali
Can you go over barometers and other parts not to coat or how to uncover if you have coated them?
soak it with alcohol, the coating should dissolve. Then leave it to dry completely.
seems like this stuff just killed my board … not sure how , I used this stuff on many board before , maybe I put on too much …
what can I dip the board in to remove it ? just alcohol ?
Nice job, different conformals are a good cheap solution for moisture control, but unfortunately, application methods often cause more issues than they resolve. Your explanation is most helpful and anyone wanting to try conformal coating should read it all t.o avoid many of the pitfalls that can occur.
Anyone using Tropicoat (electronicaembajadores.com/en/Productos/Detalle/HR11060/tool-instrument/aerosol-spray/jelt-7361-tropicoat-400-ml-tropicalised-varnish)? I’m using it but don’t know if it’s doing a good job?
Hi Oscar,
It’s important to say, waterproofing component isn’t cover by the warranty.
It’s happened to me, twice, with two different ESC and each reseller won’t take my product. (Considered like a modification)
So i prefer protect them from humidity and hope they can survive in the water with no warranty than a burned component without warranty anyway :p
A very big thanks for all your work ! you help so much the FPV community ;)