Last month we received an iphone 7 in the post from another shop after they had cleaned the motherboard for water damage. The board did not look very corroded, just a few spots but nothing major.
We plugged it into our power supply which showed us that there was a short on the VCC main power line. We removed the board and checked for heat which seemed to come from the bottom of the board on the back near tristar. We looked and could see one cap C3710 near the tristar IC that was discoloured, we removed this and the short cleared. Next we assembled the phone and tested that it would power up, it did.
We then tested basic functions and found that the home button and taptics where not working. There was a lot of corrosion around the home button FPC so tested it with a new screen, which brought back the button functionality but not the touch ID. i then checked the button properly under the microscope and found that the fpc was very corroded. 2 pins had separated from their pads and where not connecting to the flex. We resoldered these connection and tried again on the new screen which resolved the issue.
We still had no taptics so searched the board for a reason, we found corrosion around U3502 the arc driver that is connected to the taptic engine so we removed it, we cleaned the pads, reballed the IC and refitted it. The taptics kicked back in and we had another fully working phone. This repair did take a little longer than most due to there being various faults but we still had it back up and running within 48 hours, if it was just a data recovery job then we could have turned it around a lot faster but as the client wanted their phone back working so we did the extra work to suit their needs.
Just another service offered by the team at microsoldering repairs.