Reflow/Reballing to Fix the iMac's GPU?

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iMac Intel 27"

27寸 iMac 的维修指南和支持

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genik @genik

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发帖于: 2024年9月27日

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Reflow/Reballing to Fix the iMac's GPU?

The 2009-2011 iMacs GPU failure issue is a very well known one. It can lead to trashing such a great iconic computer like the 27" iMac.

Im not sure weather the overheating either burns the gpu chip or melts the gpu chips solder that causes the gpu failure. So i was wondering, can a solder Reball or Reflow make the gpu workable again?

There are YouTube videos stating this...
https://www.youtube.com/watch?v=Lpa5B6bC...
Id love to read your comments :-)

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DanJ @danj

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The video shows someone replacing the GPU MXM board back in 2018. Sadly, finding a working replacement would be close to impossible as most have died and there are a lot of people trying to sell you junk. So that’s just not a good solution.

Reballing the chip it’s self won’t really fix the failure as all you are doing is remounting the carrier to the board not the internal flip chip contacts that encounter tin whiskers shorting out or a pass-through pad has severed. The process might help but it won’t be stable very long.

Given the amount of work, I would just get an M2 Mac Mini or wait a bit for the new one coming next month and convert your 27” into a monitor for it!

I have one in my storage locker that I’m going to convert into a display my self.

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Thanks Dan.

If i understood correctly, you are saying that chip Reballing wont help because the chip is firstly mounted on a carrier, that is mounted on the board... and that carrier has solder issues it self?

Is this what needs to be done? https://www.youtube.com/watch?v=b5WnTJCF...

由 genik 完成的 2024年9月27日

@genik - Th vid you’ve pointed to shows a directly mounted silicon chip to a green carrier board. The chip is directly bonded to the carrier board and has no cover.

Here we have a flip chip design so we have a larger interface between the carrier board and the chip within which uses pins. These pins (tin), tend to sprout tin whiskers! This is when the electron's can jump across the air gap creating an electrical pathway the larger current can flow through. Think it like lightning but at a much smaller distance and voltage.

The other issue is the soldering of these pins break free so there is no electrical pathway. Both of these are within the sealed metal cover of the chip within.

So re-balling has no effect on them directly. But! The act of heating the chip can melt away the whiskers as well as reconnect the severed pins connection. In either case the outcome is likely short lived. So if you are so gun-ho, just heat the chip and hope for the best.

由 DanJ 完成的 2024年9月28日

Thanks for the reply and xcuse me for insisting.

This is a pic of my gpu https://ibb.co/HhZ6f1v

With the very little i know, isn't it similar with the one in the video i posted before?

由 genik 完成的 2024年9月28日

@genik - What system is this from? This isn’t a Radeon HD 6970 as that would have a lid.

由 DanJ 完成的 2024年9月28日

@danj its an ATI Radeon HD 5750 with 1 GB GDDR5

由 genik 完成的 2024年9月28日

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Thanks Dan.

If i understood correctly, you are saying that chip Reballing wont help because the chip is firstly mounted on a carrier, that is mounted on the board... and that carrier has solder issues it self?

Is this what needs to be done? https://www.youtube.com/watch?v=b5WnTJCF... — genik
@genik - Th vid you’ve pointed to shows a directly mounted silicon chip to a green carrier board. The chip is directly bonded to the carrier board and has no cover.

Here we have a flip chip design so we have a larger interface between the carrier board and the chip within which uses pins. These pins (tin), tend to sprout tin whiskers! This is when the electron's can jump across the air gap creating an electrical pathway the larger current can flow through. Think it like lightning but at a much smaller distance and voltage.

The other issue is the soldering of these pins break free so there is no electrical pathway. Both of these are within the sealed metal cover of the chip within.

So re-balling has no effect on them directly. But! The act of heating the chip can melt away the whiskers as well as reconnect the severed pins connection. In either case the outcome is likely short lived. So if you are so gun-ho, just heat the chip and hope for the best. — DanJ
Thanks for the reply and xcuse me for insisting.

This is a pic of my gpu https://ibb.co/HhZ6f1v

With the very little i know, isn't it similar with the one in the video i posted before? — genik
@genik - What system is this from? This isn’t a Radeon HD 6970 as that would have a lid. — DanJ

iMac Intel 27"

Reflow/Reballing to Fix the iMac's GPU?

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