Mobile phone water (liquid) damage

[dubi123]

What kind of damage water does to mobile phone (no salt, no sea water). I have an example of mobile phone that was exposed to water for less than a minute, have turned it off and pulled out battery almost immediately and dried it but it doesn't work any more (after days of drying, all methods, mild heat, rice, air-conditioned server room with low humidity). One would probaly think that it burns electronics, but again this small currents through water doesn't seem to me that would cause damage within minute (in a past I have accidentally short circuted CMOS CD4011 and didn't damage it, the chip was hot - again it was not watter but I it was short circuit from the gate output to the ground or so).
Now we have moisture indicators in mobile phones to reveal if phone was exposed to liquid (as I have heard they hide it from users to deny service requests, why hide it from users, tell them that there is moisture sensor inside). If there is already moisture indicator couldn't it be much better to use some sensor to immediately switch of the phone and minimize potential for damage. By the way there is also g sensor included in a phone (could detect free fall). And why not make some protective coating over the PC board to be more resistent agains liquids (heating problem? I don't think so). Looks like producers cont of significant percentage of mobile phones (20% ???) to be damaged by "liquid damage" and increase sales. I didn't go to service with particular mobile, but anyway why hide fact about mositure sensor sounds from user.

Now I am guessing what kind of damage is done to phone, oxides that act like 10k to 1M resistor between pins or wires on PC board, don't know.

Regards

Dubi

 

[itsmoked]

The moisture indicator is not hidden.

Open the battery compartment and remove the battery. It will be in plain sight. It's a piece of white paper that turns pink once wet. It has to be in plain sight so when you take it into the pone store, they can pop the back off, visually check it, and wave the pinkness in your face. Then the procedure to sell you a new phone can commence.

What does the moisture do? It electrolyzes the minute traces and in some cases reverse bias's parts. Since the phone runs on very low voltage and the batteries are exceptionally powerful everything goes to hell in a minute.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[dubi123]

Thanks! I know where this indicator is, it was behind memory card and on a battery (so at least two sensors). But, if voltage is low, why than this cause havoc so fast. I don't think that currents involved are above 1 (or few) mA (just guess). And again, why not some protective coating (paint).

 

[mcgyvr]

dubi123.. If you were making and selling a product that people want priced cheaply, would you spend the extra money and reduce your profit margins and make it so hefty/rugged that the user would never need to purchase your product again?
No because you would go out of business quickly.
They want you to drop your phone in the toilet so you have to buy another one.

 

[OperaHouse]

I did that to a phone. Got it wet and dried it out. Seemed to charge ok, but phone wouldn't work. I tried everything for days. Finally I realized I had to turn it on. Something I hadn't had to do for more than a year, just too used to flipping it open.

 

[Noway2]

Last weekend I had to buy a new phone. My old one sat outside buried in snow for over a week. Apparently I set it down when I went to check something and forgot about it. Then the snow storm came and didn't sufficiently melt for over a week for me to discover it.

After drying it out for a few days, I plugged it in. The display was washed out with spots on it, it would cycle on and off, repeatedly play ring tones, hiss from the speaker, and the keys wouldn't operate.

 

[itsmoked]

Another casualty of the Snowicane...

Keith Cress
kcress -

http://www.flaminsystems.com

 

[OperaHouse]

Somewhat related. Heard this story that a couple dropped a digital camera off the side of a cruise ship. Over a year later it ended up in a net of a fishing trawler. Camera was a mess but the memory card was still good. Persistent captain kept submitting it to news agencies and finally the owner was found a year later.

 

[MacGyverS2000]

I think friend's of the owner (in a different country) saw the pics and recognized the couple, gave them a call.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Noway2]

Getting off topic, but I was on a cruise and snapped a picture right as the wife came out of the shower. Wouldn't you know but that was right when the battery died! Went to the camera shop and got a battery. I was afraid that they would want to put it in and that picture would be on screen. It wasn't. Learned my lesson.