Eli5: How are phones waterproof even though the charging port terminals can be exposed to water and not short circuit them?
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The ports are insulated and covered in hydrophobic material (material that naturally repels water). Also, charging ports could still short in that situation so many phones have sensors that stop the port from accepting electricity if moisture is detected inside the port.
As others said “water resistant”.
But for the ports, there’s a few tricks the most commonly used is to have moisture detection in the port. This is pretty trivial, basically you have a circuit that measures capacitance and if that circuit detects a change in capacitance (there’s a big difference between the capacitance of air and water) then the phone will disable the port as well as the ability to charge the phone until that’s no longer the case.
No power in the port means no short circuits.
Of course, your ports are still vulnerable to corrosion from exposure to water but the components in a phone are decently resistant to corrosion.
They put a nano coating of this tiny hydrophobic liquid around the seems and port of the phones. This makes it so water dosen’t want to touch the phone in the first place and can’t “stick” to it so to speak.
This nano coating is basically just a type of glue. Most brand new phones can survive hours submerged underwater because the seals around the phone haven’t been abused yet. The older your phone the more time it’s been dropped, had the hot and cold thermally expand and shrink the phone’s materials breaking the bond of the seams.
Swimming with your phone can put enough stress onto the material and force water into your phone. Kinda like pressurizing the water into the phone in a way. The deeper the phone goes in a pool (hypothetically) the less chance of that phone surviving due to the increase of pressure. (I’m sure you’ve had your ears build up pressure when you dive into a deep pool, same idea as that).
There is no insulation in the connector, water will prevent the ports from working and if you keep trying to charge it when wet, voltage and water working together will quickly corrode the contact pins.
However it is still water resistant by mechanically sealing the whole connector and in fact any holes and cracks for buttons, speakers and the screen, preventing any further liquid ingress into the phone.
In addition to the factors mentioned by other users, another factor which protects the ports is the fact that they don’t need to be highly energized when there’s nothing in the port. Unless you’re charging, the voltages on the power in pin can be left low, and any sensing pins do not have to be powered (or, if connected to a reference voltage [pullup], have high internal resistance and can’t push much current), so as long as there aren’t any gaps from the port into the phone, the port itself won’t short.
To add to other responses, it’s not the water that kills electronics. It’s the water along with the electricity that will kill it.
You could dunk an entire circuit board into water and as long as you fully dry it, itll work fine. This is what some people do with ultrasonic cleaners.
CAT (as in CATEPILLAR) Work phones do it very simply. They have a rubber hatch over the USB and 3.5mm jack that you close when you’re not recharging the phone or using the jack.
Water will short the charging port, so the phone looks for a short. If the phone detects a short, it says “hey there’s a short. That probably means there’s water in the port, so I’m gonna turn off the port until the short goes away”
No damage is done as long as the moisture doesn’t exist in the port while it’s on.
Charging terminals are a power *input*, not a power *output*. There can be a dead short across them and it’s not a big deal. Water resistant phones can also detect abnormal current leakage between contacts when you plug something in to charge the device, and it will let you know the port is wet. Hit it with some canned “air” and blow the water out, and it will continue to work just fine.
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