hey guys,
can someone guide me here. as the title says, i spilled alcohol on a smartphone board i was fixing while it was in charger. alcohol drops fill specifically in the purple dotted region. it made sounds like it was evaporating, then complete silent. now the smartphone is completely dead and doesn't even feel the charger.
attached is a repair manual screenshot of the damaged area.

 

Welcome to AAC.

Usually with an alcohol spill you just let it evaporate till dry. But having power on the circuit might be fatal. It appears to be so in your case. I would just say let it dry. Use a hair dryer on low temp low air speed and slowly dry it out. Then hope for the best. See if it will power up. It might. It might not.

 

Organic solvents such as alcohol and glycerin are conductive. Before powering up the board you will need to make sure that the board is clean and clear of both.

Alcohol will eventually evaporate but if it has any impurities in it they may get left behind and create conductive paths which can harm the board or make it not work properly. Glycerin is not likely to evaporate, at least not in any short period of time.

I'd suggest getting some higher purity alcohol. 70% is not good enough, it has too much water in it. Drug stores sell 91% isopropyl alcohol that will do the trick. Industrial suppliers usually have 95% or better. Use the alcohol to rinse off the glycerin. Use compressed air to blow it out from under integrated circuits on the board. You may have to rinse and repeat several times.

As well, make sure that, while handling the board, you work on an anti-static mat and use a wrist strap.

Again, make sure the board is dry before powering it up.

 

Welcome to AAC.

thank you

It might not.

it appears to be the case

 

I'd suggest getting some higher purity alcohol. 70% is not good enough, it has too much water in it. Drug stores sell 91% isopropyl alcohol that will do the trick. Industrial suppliers usually have 95% or better. Use the alcohol to rinse off the glycerin. Use compressed air to blow it out from under integrated circuits on the board. You may have to rinse and repeat several times.

i appreciate it, will do that

 

It looks like you would be better off with Methanol (Methyl Alcohol). https://www.aciscience.org/docs/Glycerine_-_an_overview.pdf BTW, Methanol won;t attack plastics.

Glycerine is soluble in water too.

I now have my own technique in dealing with wet stuff that has worked on a few occasions for a DVM that got wet. My concern was protecting the LCD. My cell ended up outside for a few hours when raining.

In both cases, it wasn't dirty water.

It was important to me to keep the device in the orientation found and remove the batteries. Then dry it off the best I could, again not changing the orientation. Then place in a bag of rice at least overnight.

 

it wasn't dirty water.

the phone I'm talking about tasted the saltiness of the sea

 

the phone I'm talking about tasted the saltiness of the sea

Ouch. Saltwater is corrosive. You can rinse it well with clean fresh water, but you'll want to make sure it's dry before applying power.

That's probably a good way to go. Rinse well. Water should be fine unless you see oils or anything not soluble in water in which case, use alcohol. Use compressed air to dry, then a rice bag over night. Once it's dry look it over for any residue and repeat if necessary before power up.

 

@0100hem - if you heard noise, you were hearing a problem. Use a microscope and look at the chips in the section to see if there are any 'volcanoes' in them, pieces blown off, or discolored/burned/marked. Looks like a DC DC converter in the 'wetted' section. Silicon chips can absorb moisture- only way to remove it (if the chip is ok) is to go through a 'bake' process (low and slow) and evaporate it.

Looks like your repair job just got bigger.

 

It's important to be clean and dry.

Tektronix used to put scopes in the dishwasher with a strict procedure. I don't reccomend that. Gyycerine CAN BE corrosive to copper.

 

It might even be, since the thing was powered when it happened, and you did not instantly disconnect the power, that the only option is to recycle responsibly. But first it does need to be cleaned off and the dried completely. That includes the areas under those large flat-pack ICs.