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Thursday, 4 April 2013

Why does a wet phone die?

I wouldn't say I am an accident prone person, but statistically I have destroyed a disproportionate number of phones due to water damage. One of the things that struck me, was how sometimes, if you’re quick at getting your phone out of the water and you turn it off, then pray to the phone Gods and keep your fingers crossed, sometimes, just sometimes, it magically comes back on again the next day…(at least until a week or two later when it starts acting ‘funny’).

In order to get a better understanding of what’s going on with a wet phone, I had a chat with the team in the P2i labs.

What happens when your phone gets wet?

There is a magnitude of possible outcomes when your phone gets wet. If you think about the number of entry points for water to get in the phone, then times that by the number of possible angles of entry, force of entry, droplet size (fully submerged, spray, mist, sweat) and type of liquid, you begin to see why the answer is not so black and white!

Perhaps one of the most obvious outcomes is that your phone ‘short circuits’ and powers out. If you think of a circuit board like a series of motorways, in the same way that we drive cars according to the direction and paths provided, the circuit board controls the flow of electrons, ensuring that your device works as specified. However when you add water to the mix, it’s like driving cross country or along sand dunes where there are no roads to act as a guide. As a conductor of electricity the water allows the electrons to flow freely.

With the liquid inside the phone allowing the electricity to flow in unintended directions, the essential voltage differences across the circuit board are interrupted, causing excessive electric current, heat and power outage.

Ok, so if I’m lucky enough to have my phone turn back on, why does it start going ‘funny’ after a couple of days/weeks?   
If you have ever opened a water damaged phone or piece of electronics you may have seen what looks like rust or a perhaps a white powdery substance. In the first instance the water or liquid is interacting with the metal causing a chemical reaction, as you would see with any metals exposed to the elements, like a tin roof. Except unlike the roof, the addition of energy supplied by the phone under power, accelerates the process. This causes degradation and wearing away of the metals inhibiting them from performing effectively. This is particularly evident in devices that are used in environments such as the gym or are kept close to the skin like headphones and hearing aids, where the addition of the salts in our sweat aid in the severity of the chemical reaction.

So what is it that makes a phone die altogether? 
Well this takes us back to the highway analogy. There is a type of corrosion called ‘electrochemical migration’. This is essentially the movement of metal ions from one point on a circuit board to another. This is able to occur because the water allows the free flow of electricity; so where once there were paths for the electricity to flow, allowing controlled differences in electrical charge between different points on the circuit, now  the water allows the metal ions to migrate. Eventually the metal ions will bridge the two points through the formation of a metal dendrite, acting as if a new road was created. Now, even when the water recedes, this new road permanently disrupts the control of electricity on the circuit board and the phone is no longer able to function as intended.
video

Do you have any advice for people who get their phones wet?  
It’s key to stop the electrical flow as soon as possible so first thing is to take the battery out. Then dry any excess visible water – worth noting that you should avoid trying to shake the water out as you may be inadvertently forcing it further into the device. Leave the phone to dry out completely before succumbing to the urge to test it…and unless it’s a Motorola or Alcatel device already treated with P2i’s tech, than feel free to keep your fingers crossed. 

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