Mar 30, 2020
Water damage of iPhone is common during daily using. In our blog today, the home button of iPhone 7 is not working because of the corrosion and breakage of lines on the logic board. Since there is a high failure risk in repairing, REWA LAB presents you a repair solution to fix heavily corroded and damaged logic board step by step with Ultrasonic Cleaner and Enameled Copper Wire.
When handling a single logic board issue, the first thing we do is always to check the logic board carefully. We can see that the logic board bears obvious signs of water damage and mouldy connectors. It is also seriously corroded.
First, let’s complete a preliminary cleaning with PCB Cleaner. Then assemble the phone and test. The phone turns on normally. Yet the Home Button is not working and the phone can not go on with further activation.
Check the logic board under the Microscope carefully. We can see that components next to J3801 are mouldy and circuits on the board are seriously corroded.
Since the logic board is seriously water damaged, there might be signs of water damage under the shielding cover. So we need to detach the shielding cover from the board and clean the logic board thoroughly.
Detach the shielding cover from the board with Hot Air Gun and scrub shielding paster off the board. Pour adequate PCB Cleaner into the Ultrasonic Cleaner. Then put the logic board in. Press the power button to power on. The Ultrasonic Cleaner will then start to work. Take out the logic board after 15 minutes.
We can see that due to the corrosion of circuits on the board, there are parts missing on bonding pads of FL3803 and FL3802. This might be the cause.
Troubleshooting - Jumping Wires
Our next move is to connect the disconnected circuits with Enameled Copper Wire of 0.1mm in diameter.
Jumping Wires #1
With one end of the Enameled Copper Wire soldered to Pin 1 on C3803, the other end goes under the shielding cover, and then is soldered to Pin 1 on C3702.
Jumping Wires #2
With one end of the Enameled Copper Wire soldered to Pin 1 on C3822, the other end goes under the shielding cover and then is soldered to Pin 1 on C1926.
Jumping Wires #3
Since one bonding pad of FL2901 has been corroded, we can connect the two bonding pads of FL2901 with Enameled Copper Wire about 0.1mm in diameter.Once done, run diode mode measurement of J3801. The measured value is normal.
Reassemble And Test
Assemble the phone and test. Press power button to turn on the phone. The phone goes normally with activating page. Press Home Button for further activation. The phone can not be activated with some WiFi failure.
So we can activate the phone by connecting it to the computer. Touch ID can be activated this time. The phone is also successfully activated. Home Button failure fixed.
For tools and parts used in the video, please click the link below or visit REWA Online Shop.
You can also visit REWA YouTube Channel to check our video and learn how to repair a not working home button step by step.
Apr 23, 2021
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