iPhone 6 no power - Hot power ic

[caphair]

Have a water damaged iPhone 6 that's been cleaned of all corrosion, however upon applying power the power management ic gets really hot and I measure 100mv to ground on all the surrounding smd caps

I'm wondering if there's an easy way to determine if the ic itself is shorted or one of the smd caps?

It's so tightly knit that simply unsoldering wouldn't be easy and the ic is BGA

The power ic is highlighted in yellow

[ReeceyBurger123]

Re: iPhone 6 no power - Hot power ic

Possibly water under the bga chips shorting it out. Maybe try a reflow see if it helps ?

[caphair]

Re: iPhone 6 no power - Hot power ic

Hmm it gets so hot I'd imagine any water under there would be dry

[stj]

Re: iPhone 6 no power - Hot power ic

dont iphones have underfill-resin on the bga's like nokia first started?

[caphair]

Re: iPhone 6 no power - Hot power ic

Yes they do, would that prevent any water getting under there? Isn't underfill used to hold components in place during soldering?

[caphair]

Re: iPhone 6 no power - Hot power ic

Here's the section of the power management ic I'm looking at. Most those caps measure shorted and trying to figure out which one it is or the chip.

However the diagram is a bit confusing, are all those caps tied to the buck section?

[fzabkar]

Re: iPhone 6 no power - Hot power ic

All the buck regulators appear to share a common supply. The fact that the chip is hot while its supply is low (100mV) would confirm that it is the chip itself rather than a capacitor that is responsible for the overload.

[caphair]

Re: iPhone 6 no power - Hot power ic

All the buck regulators appear to share a common supply. The fact that the chip is hot while its supply is low (100mV) would confirm that it is the chip itself rather than a capacitor that is responsible for the overload.

Thank you for that, wasn't sure how to determine exactly if it was the ic itself

[caphair]

Re: iPhone 6 no power - Hot power ic

Do you know the difference between vcc_main and vcc_main_s in that diagram?

Also what would the "desense" caps be?