Like the title says, what are the damage mechanisms when there is no current flowing in the electronics? Additionally, what methods do hardware manufacturers use to “waterproof” electronics?
In: Engineering
It doesn’t. But just because you think a piece of wet electronics is now dry doesn’t mean water isn’t still in there somewhere. I found that I can perfectly dry old Nintendo or Atari cartridges since it’s just a chip on a board. Modern stuff can be more difficult, especially any electronics with moving parts, like motors. And you still have the problem that you may think there’s no current because it doesn’t have a power source, but the capacitors still had a charge, and you shorted them with the water.
Waterproofing generally involves just keeping the water away from the electronics through the use of sealed enclosures.
Couple different ways.
One important thing to understand is that it’s pretty difficult to get all the moisture out of, say, a laptop.
People spill a drink on their laptop, let it dry for an hour or so, and then turn it on… but there’s still liquid inside and causes a short somewhere.
I had somebody recommend allowing a laptop to dry out for a full week – while placed keyboard-side down on a towel or similar – before attempting to power back up.
(Source: My kid has damaged a couple of computers like this – I’ve had extensive conversations with the local repair guy.)
The other big problem is that moisture can lead to corrosion of important elements. (I’ve had to throw away more than one pair of cheap ear buds because the charging terminals would corrode due to sweat.)
Water, as we encounter it in our daily lives, is not just water – it’s also whatever minerals, contaminants, and detritus it picks up as it flows. Electronics are full of metals that are susceptible to corrosion when exposed to water, and even once that water is gone, all of the things that may have been in it can ruin things like integrated circuits or things with mechanical moving parts.
As far as waterproofing goes, the main goal is to limit where moisture and water can get in – outside of things fully encased in an outer shell, ‘waterproof’ is really a misnomer – water resistance is the name of the game.
The gold standard for water protection is [conformal coating](https://en.wikipedia.org/wiki/Conformal_coating ). This is expensive, renders repair impossible, and reduces heat dissipation. It’s the sort of thing the military sometimes does to protect submarine parts, not something that happens to a laptop. You also have to design the product for this sort of protection, so that capacitors and batteries can’t do damage when connector pins get wet.
Normal things you might buy have IPxy ratings. The first digit (x) describes the size of particle kept out, for water you need a 6 here as water molecules are super tiny. The second digit (y) describes how much water the device can keep out, from 1-2 which mean it can resist rain touching it and running off to 7 which means it can resist being under 1m of water for 30 minutes to 8-9K which can resist pressure washers and the like.
Water damage to an unpowered electronic device comes in three forms: Retention, corrosion and contamination.
First, retention. When water gets into an electric device, it will flow into every little crevice it can. It can be difficult to get all of the water out once it’s in, and water can cause a number of problems once it’s in. Ignoring any problems with electrical shorts (we’ll get to those), the heat of the device can flash-boil small amounts of water, and the resulting steam can cause problems on its own.
Second, corrosion. In the presence of water, certain materials used in the device may corrode. This changes the electrical properties of these materials and may lead to permanent damage when it’s later powered on.
Finally, contamination. Water on its own is mostly electrically neutral, but it’s also a very good solvent. Most water that you come into contact with is not pure water, but rather it contains copious amounts of trace minerals. These minerals, suspended in solution, can often be good conductors of electricity. And when water gets into your device, it can leave deposits of those minerals behind even after the water evaporates off. These mineral deposits can then cause electrical shorts, damaging your device.
Additionally, since water is a good solvent, it can dissolve some materials used in the construction of the device, and deposit those materials onto the rest of the control board – again causing electrical shorts.
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