Sep 17, 2021
Hello everyone, our handwork course today will be a tutorial about desoldering & soldering of iPhone X PMU.
Attach the upper layer of the motherboard to the PCB Holder. Stick High-temperature Tape on components around.
The first thing we do is to remove black adhesive around PMU. Heat with Hot Air Gun at 280℃, air flow 3. And remove black adhesive around the chip with a specialized knife.
Tips: since components around are close to PMU we need to be careful when removing black adhesive to avoid knocking components off the board.
Continue to heat up PMU with Hot Air Gun at 330℃, air flow 5. Also when heating, get one lever of the tweezers fixed first. 15s later, as solder starts to melt, pry up the chip quickly with the other lever. Tips: make sure you pry up the chip at the right time. Otherwise, the bonding pad might get damaged.
Next, let's clean the bonding pad. Apply some mid-temperature Solder Paste to the bonding pad. Heat with Hot Air Gun at 280℃. Meantime, clean the bonding pad with Soldering Iron at 360℃. Continue to clean the bonding pad with rosin soaked Solder Wick. Clean with PCB Cleaner afterwards. Tips: bonding pads of those empty pins might get knocked off the board when cleaning the bonding pad, which is normal. We can just leave them alone .
Continue to remove black adhesive on/around the bonding pad. Also when we pry up the chip, components around get knocked off the board. So our next move is to re-solder these components. First, apply some Paste Flux to their bonding pads. Then, apply solders with Soldering Iron. Get these components in position. And then solder with Hot Air Gun at 330℃, air flow 3.
Before soldering the chip, clean the bonding pad again. Clean with PCB Cleaner afterwards.
Also when we remove the black adhesive, some of the insulation varnish on PCB has fallen off the board. So we need to remedy with the UV Curable Solder Mask. Dip some UV Curable Solder Mask with tweezers. And apply the solder mask to the exposed area. Then, solidify with the UV Dryer Lamp for 5 minutes.
Now we can solder the PMU. Apply some Paste Flux to the bonding pad. Get a new PMU in position. Make sure you put it in the right direction. Solder with Hot Air Gun at 330℃, air flow 3 for 20s.
With the chip sinking and Paste Flux flowing, continue heating for 10s. Wait for the upper layer to cool for 5 minutes. Tear off the High Temperature Tape. Clean with PCB Cleaner afterwards. iPhone X PMU soldering and desoldering completed successfully.
Apr 23, 2021
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