# ASUS ZenFone 2 eMMC replacement questions



## itsakjt (Jul 25, 2020)

Hello everyone.
This is just for fun and self learning activity. Any help is appreciated. 
I have a ZenFone 2 32 GB with a faulty eMMC chip. Also, I happen to have a donor 64 GB motherboard with a good eMMC but with fault on network and camera flash due to water damage. The 64 GB motherboard boots up but cameras don't work and there is no network.
If I take out the good 64 GB eMMC and put it on the good board with the faulty 32 GB eMMC, will it boot up right after or do I have to flash it?
Both motherboards are from the same phone model.


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## Caring1 (Jul 26, 2020)

It should be a straight swap, no different than adding ram as the phones Rom already allows 64GB eMMC for those.
Let us know your progress.


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## itsakjt (Jul 26, 2020)

Caring1 said:


> It should be a straight swap, no different than adding ram as the phones Rom already allows 64GB eMMC for those.
> Let us know your progress.


Thanks. Will definitely do. Looking for a BGA 153 stencil for the chip.


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## silentbogo (Jul 26, 2020)

Oh, that's gonna be one helluva headache for you, bud. 
Few tips:
1) Use PCB pre-heater. Otherwise I guarantee you'll have a couple of missing pads on eMMC IC. This will also help with minimizing risk of overheating and killing the IC.
2) Get a small vial of 0.09-0.1mm solder balls. Don't use paste (at least not on your first few attempts, and not with cheap stensils). Thin stencils do warp a little with heat, which causes solder paste to flow underneath and stick together.
3) Don't use those cheap spring-loaded BGA holders. It'll warp the stencil. Either tape the whole thing to the desk, or get a decent BGA rework kit.


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## itsakjt (Jul 26, 2020)

silentbogo said:


> Oh, that's gonna be one helluva headache for you, bud.
> Few tips:
> 1) Use PCB pre-heater. Otherwise I guarantee you'll have a couple of missing pads on eMMC IC. This will also help with minimizing risk of overheating and killing the IC.
> 2) Get a small vial of 0.09-0.1mm solder balls. Don't use paste (at least not on your first few attempts, and not with cheap stensils). Thin stencils do warp a little with heat, which causes solder paste to flow underneath and stick together.
> 3) Don't use those cheap spring-loaded BGA holders. It'll warp the stencil. Either tape the whole thing to the desk, or get a decent BGA rework kit.


Thanks a lot. I will surely keep those in mind. 
Another thing I want to mention. The motherboard of this phone has the CPU with the RAM as PoP located just opposite to the eMMC on the other side of the board. But that package has underfill on it unlike the eMMC. I hope that won't cause a problem.


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## itsakjt (Sep 4, 2020)

I did it I did it. 

eMMC removed from water damaged donor board:
















And success:





The phone works absolutely good as new. I filled up the storage as much as possible to test out the stability of the eMMC. 
The phone booted right after the replacement as you all said. However it would not detect the SIM 1 card. On further inspection, I found the baseband firmware was not initialized and the SIM 1 IMEI was shown as NULL. Did a full flash using ASUS Flash tool with the latest firmware and it is back. Detects and catches network in both SIM slots, SD card slots work, cameras work, everything is great. 
Thanks for the inputs everyone.


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