Why does water “destroy” electronics and how does waterproofing work to stop this
In: Technology
As others have said, water conducts electricity (technically ions in water conduct electricity, water itself isn’t very good at that) so if you allow a “shortcut” on a circuit board (like across the battery) then the rest of the circuit won’t get the right power it expects. Since modern electronics use fast and very specific signals, this screws up the whole thing.
On waterproofing, the goal is to prevent water from getting in, but the “how” is actually a bit more interesting. Usually you try to create a seal by compressing rubber, glue or another polymer to fill the cracks on a seal.
This doesn’t work for everything though. That also obstructs airflow. What’s the problem with that? Well sound travels through air, and if there’s no airpath, then your microphone and speakers would sound very muffled by the seal. For those seals, phone manufacturers use a special hydrophobic (means it doesn’t like water) mesh that allows openings, but the surface tension of water will not allow it to get through without time and pressure (i.e. if you dropped it into a pool and left it there). Switches and buttons have their own ways of waterproofing allowing them to move while maintaining a seal.
When you see “IP67” that’s the “ingress protection” rating, that means it passed a very specific test. The first number is for dust ingress (with 6 being effectively no dust allowed in) and 7 denoting a 30 minute test at 1m deep in water with no visible drops inside. That’s also on a new device and doesn’t take into account rubber degradation over time.
Water contains Impurities that make it conductive to electric current, when a piece of electronics gets wet the current flows where it should not go and can damage the components.
Water only damages electronics that have a power source, electronic boards are sometimes washed during their manufacturing process with no damage as they are not powered at the time.
Since it’s liquid, it can get into all sorts of cracks and crevices. Water is a very good electric conductor, so can cause the electronics to short out by making current go where it’s not supposed to, like a circuit board.
Waterproofing seals up the cracks, preventing the water from getting in.
Well, two things.
1. Water conducts electricity. This is a problem when you have small electronics that are wet because then the electric current no longer follows the correct paths, instead it follows the paths that the water creates… This is bad.
2. Water Corrodes. Most of the exposed components include various metals, which can rust and become unable to effectively transmit the required electrical current to operate certain components. These small components rely upon specific voltages to be supplied in order to function.
Waterproofing effectively insulates these components from both the electrical conduction and the corrosion via various methods. Sometimes it’s simply removing any ingress points, other times it’s physically coating the electronics with plastic or other non-permeable membranes.
Water is conductive – it is a pathway for electricity to travel through. When you get water on an electronic device that is powered on / charged, you’re introducing pathways for the electricity to go to places where it’s not supposed to go, and that can damage those parts of the computer so that even after the water dries up, the electricity isn’t going where it was supposed to go originally according to the original design of the part.
Waterproofing just helps keep water out of parts where electricity/electrons are flowing. If the water can’t get there, it can’t open up those other pathways to fudge up the part.
Rainwater and tapwater have a small amount of sodium, magnesium and calcium in them. Not enough to make the water very conductive, but enough to make it an “electrolytic solution”.
An electrolytic solution is a chemical where, if you put two different metals in it at different voltages, ions will start exchanging between the two metals, causing them to chemically change.
Electronic circuits use a lot of copper and iron. When you get electronics wet, that can corrode the copper and iron. When you get them wet *and* you have them powered on, the corrosion happens much more quickly because the water is an electrolytic solution.
As things corrode, the water may leech some rust or other corrosion products across the circuit board, short-circuiting things and causing strong enough electrical currents to burn something out. Or, a connection might corrode badly enough that it stops conducting electricity and so it no longer works.
There are a handful of ways that this can be avoided in a product that is expected to get wet:
* Waterproofing, like we do with cell phones: The body of the device is well sealed so that water can’t get in to the circuits.
* Dielectric grease: If there’s only a few minor places where water ever gets in and it doesn’t get in too badly, just smearing some grease on the component or connector can keep water off of it well enough.
* Conformal coating: The circuit board can be sprayed or painted or dipped in a chemical that’s kind of like a clear paint intended to be an impenetrable shield against water.
* Potting: A block of plastic resin can be cast around the circuit.
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