I spilled water all over my powered up Uno today. It stopped working... until I dried it off, then it was fine. Later I was testing a project in a closed box that went to 100% humidity. The display was dead when I took it out of the box... until I dried everything out, then it was fine.
Now I know you can kill at least some electronics permanently with water. I've done that with a P&S camera, getting water inside while it was powered up. Drying it out made no difference.
But what about our little Arduinos and similar low power circuits? Is it less likely that a short due to moisture will fry anything? Or did I get lucky today?
I think, they intentionally make all complex electronics devices, cameras, phones, tablets etc. sensitive to moisture, one way to increase of market and consequently profit. Otherwise, there is no difference between arduino and your P&S
Pure water is not a problem, as it has extremely low conductivity. The dissolved salts are the real problem, so if something gets soaked by impure water, the best treatment is to rinse the object in distilled water before drying.
That makes sense. My Uno and the other electronics were wet with tap water whereas my camera was exposed to water in a bay (the underwater enclosure leaked).
The Uno getting wet was an accident. I intentionally drove up the humidity on the other project to test it since that's something that may occasionally happen to it in actual use. It's good to know that that isn't likely to permanently damage it.
It's common practice to solder using water soluble flux and then wash with water. The trick is to dry the board before powering it on. Where I used to work we used tap water and we dried the board with compressed air (plus some additional time to make sure it was dry). Mostly this was for rework/repair rather than board assembly.
A board washing machine following a wave solder machine usually uses DI water.
If it's not dried immediately, there may be time for corrosion to set-in. That's more likely in something like a camera in a case where the circuit board can't easily be dried, and of course salt water can be very corrosive.
If power is applied you can get conductivity through impure water and that can "short-out" the circuit which might cause a temporary failure, or in some cases permanent failure.
My daughter dropped her phone in the water at the beach.
Had she thought to immediately remove the battery, it might have survived in a plausible fashion. (She is after all, an engineer, albeit software.)
That evening, I pulled it apart and thoroughly washed it in tap water (more readily available than distilled water and pretty good really). I had to rebuild a battery connection that had literally dissolved in that time, and the small pushbuttons had become unreliable (electrically leaky).
It lasted a day or two, but the buttons started to cipher badly.
A Lithium battery is very effective at powering electrolysis.
The amount of talent at work who drop there mic or talkback packs down the loo and give them a golden shower. Main thing is to remove batteries as quickly as possible and then strip the pack down and wash with IPA, blow excess off with air duster and then leave in a warm dry place for a few hours.
Electronics that use low current can generally be salvaged using the methods described but high power electronics like RC motor speed controllers tend to self destruct if you fly your model airplane into a lake. Trust me. I've only salvaged one out of several that got wet.
Twice a year we have a "float fly" at San Louis Reservoir and occasionally the sea planes
crash and the receivers and speed controls don't fair too well with the water, even after
distilled water bath and blow dry.
What about using a coating to protect electronics from a minor splash of water or humidity induced condensation? I know there are products sold for "conformal" coating of PCBs.
Would it work to simply paint a board and components with a thin layer of neutral cure silicone? Or would that cause other problems? Would it affect a crystal's performance to cover it with silicone?
jboyton:
What about using a coating to protect electronics from a minor splash of water or humidity induced condensation? I know there are products sold for "conformal" coating of PCBs.
Would it work to simply paint a board and components with a thin layer of neutral cure silicone? Or would that cause other problems? Would it affect a crystal's performance to cover it with silicone?
Hi.
I use to install Outdoors AP's based on routerboard product ( MikroTik). I always use decent PVC waterproof case with humidity aperture, a small cut 0.5 cm by 0.2 cm on the base of the case, not a hole. Water condensing will create drops over the hole, and water superficial tension, will deny the drop to fall.
I saw some time, outdoors AP's coated with insulating varnish spray.
jremington:
Pure water is not a problem, as it has extremely low conductivity. The dissolved salts are the real problem, so if something gets soaked by impure water, the best treatment is to rinse the object in distilled water before drying.
Not extremely low, just low, CO2 dissolving in from the air will raise the conductivity well above the
"pure" state as it equilibrates with bicarbonate and carbonate(*). All environmentally available water
is a conductor, basically.
So I should been able to dunk my (now deceased) camera in distilled water -- while it was turned on -- and suffer no immediate damage due to short circuits.
But would my camera have survived had it gotten wet with clean tap water (or fresh lake water) instead of the somewhat salty water that caused it to short out and be permanently damaged?
Grumpy_Mike:
No don't be silly have you not read the replies?
I read the replies but none of them answered the question I just asked.
Randomly shorting out parts will damage them. The damage migh not be enough to make it stop functioning immediately but it is damaged.
My Uno was wet while powered and was not functioning. My project was wet while powered and only partially functioning. Are you saying they are both damaged now?
All this pure water stuff is academic even distilled water will contain impurities by the time it comes into contact with your circuit.
The purity of the water contamination may be a factor. It is possible to recover a circuit board by flushing with distilled water , then flushing with IPA and drying. This doesn't always work.