How can smartphones be waterproof?

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With the charge ports, speakers, and all of the electronics inside of them, how can newer phones be built to be waterproof for such an extended amount of time? Wouldn’t water instantly seep into the phone’s cavity and destroy the electronics?

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Most of the shell is already waterproof; it’s glass and metal. The seams can be waterproofed easily enough using rubber lining the inside. The charging port and headphone jack do have electrical connections, but since electrons can flow through metal and water can’t, they can be sealed too. The speakers and mic are a bit more difficult, but at the end of the day the only part that needs to be exposed to air is the membrane that picks up or produces the sound, and that too can be sealed tight to prevent water getting in.

If you fit the parts of a devices casing so neat and maybe apply a flexible material inbetween to shut the seal, anything can be made waterproof.

Even the electronic ports with metal contacts are basically just that. Metal contacts which cable goes through the seal. But if the contacts of my charging port are wet, how come it doesn’t short the circuit and kills the phone? Well, the contacts aren’t waterproof and infact they do short the circuitry of the charging controller inside. But USB is designed to be short resistant. It simply just survives the short circuit or even shuts itself off or at least limits its power. The metal of the contacts might oxidize eventually if you keep drenching your phone with water everyday.

It’s possible to make watertight speakers and microphones, it’s possible to have rubber seals where the microSD/SIM tray slides in, it’s possible to stick the screen and backplate onto the main chassis with watertight tape, and it’s possible to make the charge port and headphone port watertight. And so on and so forth. Basically, they’re able to make every outside-facing part of the phone watertight.

Which means that the only electronic parts exposed to the water are the charge port pins and headphone port pins that connect to their cables. These can be made or coated with a metal that doesn’t rust or oxidize too badly from contact with water… so as soon as they dry off, everything’s fine.

iPhones have a tar like substance lining the inside. The tar keeps the water out. I was told this by a smart phone repair person.