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Failing GPU: alternative to reflowing?

The GPU on my MacBook Pro is starting to fail every so often, leaving it with a black screen and no external graphics when plugged into an external monitor. I’ve got two repair shop opinions saying it’s the GPU failing. Because it also works just fine every once and a while, I think a simple reflow will fix the issue.

But here is the question: without microsolder experience/ability, is there something else I can do than pay $200+ for a reflow job? For example, one microsolder tech recommended that I pop the logic board (all by itself, disassembled from the laptop) in an oven at 450 degrees for 5 minutes. If that’s safe to do, I’d much prefer that to a $200 repair, as long as I don’t risk destroying the whole thing.

You microsolder wizards out there, what would you recommend? Or where would you recommend that can do the repair for cheap? I’ve already replaced the laptop, so now I’m just repairing to resell.

Thanks in advance.

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The oven trick really won’t fix the root issue only buy you some time!

Most of the time you’ve not even getting the chip hot enough to effect the solder joints. This gets into what has really failed one of the tantalum caps (most likely) or if you have a fractured solder joint or cold solder joint. These both need flux to fix and getting off of the Tin based solder Apple uses. While I agree Lead solder is bad! It’s more an issue of where its’ used. Hot running components like CPU or GPU chips should have a leaded solder a few percents of Lead won’t be a big deal for these.

Frankly, I’m thinking you may have more of an issue with the Switching and MUX logic which you can see here on the left in this block diagram. This might only need a a new tantalum cap! Vs having a bad GPU.

Block Image

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@aprepair not sure why the tech suggested that to you. To oven is not going to fix the issue at hand. 450F for 5 minutes without bottom heater and no ramping up and cool down period is not going to reflow this. A reflow is more than just blasting some heat on it. Right now my concern would be that you need to know that it is not necessary to "to fully melt the solder" for a reflow. I suggest that you get an old board first and practice a reflow. Here are some basic temps that you will need to know "The lead-free alloy used for BGA solder balls has a melting point of 217°C. This alloy requires a minimum reflow temperature of 235°C (455F)to ensure good wetting. The maximum reflow temperature is in the 245°C to 260°C range.

When using a reflow station the profile usually looks like this :

Profile Feature

Average ramp-up rate (Tsmax to TP)

3°C/ second maximum

Minimum preheat temperature (Ts MIN)

150°C

Maximum preheat temperature (Ts MAX)

200°C

Preheat time (Ts MIN to TsMAX)

60–120 seconds

Temperature (TL)

217°C

Time above liquidous temperature TL

60–150 seconds

Peak temperature (TP)

260°C

Time within 5°C of peak TP

30sec

Average ramp-down rate (TP to TsMAX)

6°C/ second maximum

Time 25°C to TP

8-minutes maximum

All temperatures refer to the topside of the processor, measured on the processor body surface. Of course this is for a reflow station based on a lead free BGA IC.

The bottom line her is the construction of the IC (if it even is the GPU). Here is a very "quick and dirty" explanation of what causes most of the RROD. It is not always a failure of the solder balls which connect the IC BGA package to the motherboard. It does happen and you can see why [ http://www.bunniestudios.com/blog/?p=223|on here] More commonly however is that the failure is due to the chip design itself.

Block Image

As you can see the "bumps' are what actually connects the die to the substrate to make the chip complete. If these bumps fail the die does no longer make contact with the substrate and thus no contact with the circuit board. The chip has failed.

Block Image

Here you can see the space where the bump has failed and no longer makes contact. We are talking microns of space here. So a bit of pressure on the top of the die potentially close the gap. Same with a “reflow”, it may allow some of material from the bump to reshape and starting to make contact again. The subsequent heating and cooling of the chip during use is what will eventually cause it to fail again.

If it is the GPU then the only proper way to fix it would be a complete reball with a new IC which is most likely not available

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Talon sera éternellement reconnaissant.
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