To all the MacBook BGA Reball repair doctors... expert question

[JM1010]

My Macbook 1707 PMIC got hot. Removed the chip and the fifth pad from the bottom left (PP5V_S4) was burned. After carefully scraping the pad to expose some copper it shows a 0.3 ohm short. I know this is a complex issue but what is the best way to deal with this? Where is the trace to this pad is also not clear. Is it fair to assume we need to scrape away the ground plane around this pad? If so, which layer is ground: is it top or second layer?. If it's not the best way to deal with this, what do you recommend ?

Thanks for your guidance.

[Spider1211]

Re: To all the MacBook BGA Reball repair doctors... expert question

Attach schematic and boardview. From your picture, it seems the trace to the mentioned pad is gone. Can you confirm same?

It can be another component on PP5V_S4 that is shorted to ground and not necessarily the trace contacting ground. Do not scrape away layers blindly.

[JM1010]

Re: To all the MacBook BGA Reball repair doctors... expert question

Hi Spider, here are the files. The trace seems intact (assuming it's the angled trace to the bottom left of the pad. Given it's a .3ohms short on the pad I think the short is there, not sure. Could always reinstall the pmic and inject voltage...