iPhone 12 Pro Max CPU Micro Soldering Repair

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iPhone 12 Pro Max no boot issue fixed by CPU repair.

Model: iPhone 12 Pro Max

Announced: 2020, October 13

Repair Process

Disassemble the phone and find the motherboard has been separated already. It was repaired by another repair technician and the no boot issue cannot be fixed.

01 Received the phone the mothebroard has been separated already

As per the customer’s feedback, the CPU with some pads missing problem.

Remove the CPU and check under the microscope.

02 Remove the CPU and check under the microscope

As we can see, there do have some repair traces on the CPU pads.

So the previous repair technician might have tried his best, but cannot get the issue fixed.

Let’s fix these pads again!

 And among the missing pads, the marked 3 pads are the most difficult to repair

  • they are useful pads
  • they are too close to each other, later when jumping wire requires very skillful handwork and great patient

04 the 3 missing pads

First, remove the solidified UV mask on the pads carefully.

05 remove the UV mask

After removing the UV mask, the root of the pads cannot be found. (This might be the reason why the previous repair technician give up repairing)

06 After removing the UV mask the root of the pads cannot be found

keep slightly scratching with the sculpture knife till we can see a little pad as marked below

07 keep slightly scraching with sculpture knife till we can see a little pads as marked below

Finish the job of “Root” searching patiently

09 Root searching

Then apply a little bit of solder flux and solidify the roots and the pads first, then cure with the UV lamp

10 UV solidify the pads and the roots

After that, scratch out the roots.

11 Scratch out the roots

Then apply a very little bit of tin paste to each root

12 Tin paste

13 finished

Don’t underestimate these little roots, they are the new connections between the CPU and the motherboard

Then let’s jump wires like what we do on the motherboard

  1. Solder one side of the wire with the root
  2. Make a little circle with the tweezer on the other side
  3. Apply with the UV mask then cure with the UV lamp
  4. Scratch out the pads slightly

14 Then lets jump wires like what we do on the motherboard

CPU Repair

Also, jump wires on the other missing pads

16 Jump wire other pads

When all the missing pads on the CPU are fixed by jumping wire, then reball the CPU and solder it back to the motherboard. (you can visit REWA Academy to learn the handwork skills)

17 Solder back the CPU

The last step, recombine the two layers of the motherboard with the heating platform and assemble the phone to test. The phone can be booted normally, and all the functions are OK.

Summary

The issue finally gets fixed by CPU pads jump wire repair. As mentioned, CPU chip missing pad repair requires rich experienced, excellent stable handwork, and great patience.

Do more practice and then you can repair similar issues like this with confidence.

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REWA Academy

As an enthusiastic educator and expert in mobile technology, REWA Academy has dedicated its career to empowering individuals through technical education. With a keen focus on cellphone repairs, they have developed comprehensive online and offline courses at REWA Academy. Their expertise spans a wide array of areas, including iPhone repair training, phone hardware, software, and advanced troubleshooting techniques. Through their writings, they aim to demystify mobile technology complexities, making it accessible and understandable for both novices and professionals in the field.

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Do you aspire to become a professional in the phone repair industry? If so, visit REWA Academy to learn in-depth phone repair from industry experts.

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