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ITA no-boot issue in an iPhone 12 Pro Max is a challenge for repair technicians, especially when caused by missing CPU pads. This guide explains how to diagnose, repair, and restore functionality to the device by skillfully repairing the CPU pads through wire jumping and other intricate methods.
Device Details
Model: iPhone 12 Pro Max
Announced: 2020, October 13
Defect Phenomenon
Device: iPhone 12 Pro Max
Symptoms:
- The device was unable to boot.
- Previous repair attempts failed.
- Customer feedback identified missing CPU pads.
Repair Process
Initial Inspection
- Disassembled the phone and found the motherboard already separated.
- Inspected the CPU under a microscope and confirmed repair traces on the pads.
Root Cause
- Missing pads on the CPU were preventing proper connections, including three critical and challenging pads located close to one another.
Repair Process
Step 1: Remove the CPU
- Carefully remove the CPU from the motherboard.
Step 2: Locate the Missing Pads
- Inspected under a microscope to identify missing or damaged pads.
- Removed the solidified UV mask covering the pads.
Step 3: Root Identification
- Patiently scratched the pad areas with a sculpture knife to locate the roots.
- Strengthened the roots by applying solder flux and curing with a UV lamp.
Step 4: Prepare for Wire Jumping
- Cleaned the roots and applied a minimal amount of tin paste to each.
Step 5: Wire Jumping for Missing Pads
- Soldered one side of the wire to the roots.
- Created a loop on the other side for a secure connection.
- Applied a UV mask to stabilize the wires and cured them with a UV lamp.
Step 6: Reball the CPU
- Re-balled the CPU with solder balls to ensure proper connection with the motherboard.
Step 7: Reassemble the Motherboard
- Soldered the CPU back to the motherboard and recombined the two motherboard layers using a heating platform.
Summary
The issue finally gets fixed by CPU pads jump wire repair. As mentioned, CPU chip missing pad repair requires rich experience, excellent stable handwork, and great patience.
Do more practice and then you can repair similar issues like this with confidence.
