Reballing nVidia GTX470 on the Ghetto BGA Station

[Th3_uN1Qu3]

On Friday evening, as we were preparing to close shop, my boss says to me that one of his faithful customers is going to come in with a video card that's been misbehaving and he wants me to look at it.

I expected something along the lines of a 8800gtx, but instead, what he brings in is this... I immediately said that even LOOKING at that is going to cost $$. I started taking it apart as soon as he brought it in, exposing a huge motha' BGA with an IHS on it. Well, that's a big one... I'm well used to reballing and replacing laptop BGAs, but this is ONE BIG CHIP. I took only the card itself home and left the cooler and all the screws at work (i no longer have a desktop PC so i don't have a way to test it at home) and said i'll give it a shot. Told the guy we'll ring him to bring his PC in so we can test the card once it's done.

I have recently bought a big pack of BGA reballing stencils and when i saw the size of the ones meant for desktop nVidia cards i thought no way in hell am i ever going to use those. Well, i guess the time has come for me to use them.

I had my doubts i was even going to be able to lift that big motha' on my makeshift BGA station, but with the 45x45mm nozzle and a bit of patience, it came off clean. Cleaning it was a different story - due to the huge thermal mass of both the PCB and the chip, i had to use the hot air wand and soldering iron + braid at the same time to get all the solder to come off the pads. But with a bit of patience it all got cleaned up with no mishaps.

Also when reballing i had to make use of the preheater, placing the chip on a piece of floor tile and heating that up before i started heating the balls with the hot air wand, as due to the IHS there was no way i could've gotten the balls to solder to the pads with the hot air alone.

The IHS also came off at two of the corners due to the heat, which made it easier to remove. Once i got the IHS off it was obvious that it HAD to be removed - the paste between the die and the IHS was completely dried out. I have also measured the SMD capacitors around the die and there are no shorts, so it should be good. As you can see, i did scratch the substrate a bit when removing the IHS but it's only superficial and should not affect the functioning of the chip... we'll see.

Resoldering the chip to the PCB was much easier with the IHS removed. All checked out okay, we'll see on Monday if it actually works. Wish me luck.

[shovenose]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

Interesting, so these newer cards still have problems? Didn't know that; I thought they figured that shit out after the 9XXX series.

[Th3_uN1Qu3]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

This is not the same issue as with the 8000 series, where the chips themselves were faulty. Although sources say the GF100 chip still uses some of the "bad" materials, this has not been verified by anyone else in the field. It's simply the aging of lead-free solder used to solder the GPU to the card.

This card is 4 years old. It has a big, hot BGA on it with an integrated heatspreader. The thermal paste between the IHS and the chip itself dries out over time, this causes the chip to run even hotter and now more of that heat is dissipated thru the solder balls into the PCB rather than into the heatsink (which sits on top of the IHS). Continued thermal cycling, especially with lead free solder, will eventually crack the solder balls. This is why reballing is always done with good ole 63/37.

This can happen with any BGA that runs hot. I recall seeing some odd things like reballing a printer processor - which made the printer work again - so no device is exempt from this.

And there's also this:
http://www.techpowerup.com/forums/th....185046/page-2
http://forums.evga.com/New-nvidia-dr...-m1953349.aspx

I can hardly believe a driver update can kill a GPU in a few minutes, but that's exactly what this guy reported too - he hadn't updated the drivers in 1 year. He updated to the latest drivers for this GTX470, and 5 minutes after opening up a game, the card failed with colored lines and squares, then continuous loop of "display driver has stopped responding" and screen flashing, while it hadn't exhibited any symptoms before.

[shovenose]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

This is not the same issue as with the 8000 series, where the chips themselves were faulty. Although sources say the GF100 chip still uses some of the "bad" materials, this has not been verified by anyone else in the field. It's simply the aging of lead-free solder used to solder the GPU to the card.

This card is 4 years old. It has a big, hot BGA on it with an integrated heatspreader. The thermal paste between the IHS and the chip itself dries out over time, this causes the chip to run even hotter and now more of that heat is dissipated thru the solder balls into the PCB rather than into the heatsink (which sits on top of the IHS). Continued thermal cycling, especially with lead free solder, will eventually crack the solder balls. This is why reballing is always done with good ole 63/37.

This can happen with any BGA that runs hot. I recall seeing some odd things like reballing a printer processor - which made the printer work again - so no device is exempt from this.

And there's also this:
http://www.techpowerup.com/forums/th....185046/page-2
http://forums.evga.com/New-nvidia-dr...-m1953349.aspx

I can hardly believe a driver update can kill a GPU in a few minutes, but that's exactly what this guy reported too - he hadn't updated the drivers in 1 year. He updated to the latest drivers for this GTX470, and 5 minutes after opening up a game, the card failed with colored lines and squares, then continuous loop of "display driver has stopped responding" and screen flashing, while it hadn't exhibited any symptoms before.

Cool, thanks for the info, appreciate it.

[Agent24]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

This can happen with any BGA that runs hot. I recall seeing some odd things like reballing a printer processor - which made the printer work again - so no device is exempt from this.

Yeah, bad solder joints have been an ever-present problem in electronics since the start, and I don't think they'll ever go away.

[rtstorm]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

did you put leadfree ball or leaded?

[c_hegge]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

^
Read Post 3. 63/37 leaded. Reballing with lead free solder defeats the whole purpose of the reball, since it doesn't reduce the likelihood of it failing again. You might as well just do a reflow.

[Th3_uN1Qu3]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

Plus lead-free wouldn't be that shiny (picture 7) so it would take away from the experience. Mmmmm shiny. It was hard enough getting this done with 63/37 solder, i don't wanna think what would've happen if i attempted to do it with lead-free. I don't think it would've been pretty.

Anyway. We'll find out tonight if it does work, or if i just wasted materials that would've been enough to fix 3 AMD laptops...

[Mad_Professor]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

How do you keep the solder balls in place?

[Th3_uN1Qu3]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

I use direct heat stencils. The ones that you keep in place while you solder the balls to the chip. That way the hot air wand can be used without the balls getting bunched together.

If you use indirect heat stencils (the thinner type, that you fix in a jig and then remove before reflowing the balls), you must use IR or an oven to solder the balls, otherwise the air will move them around and make them stick to one another.

[rtstorm]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

Yes i use a hot plate and it great

[diif]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

An interesting thread for sure. That's one big old beast of a BGA. Fingers crossed, but i'm sure it will work.
I'm still practicing with my IR station and bought indirect heat stencils. I was worried if I used a hotplate then more heat is going though the chip (possible damage) as opposed to using my IR and heating from the top to melt the balls. I guess it doesn't matter either way as long as it's not overheated.

[Th3_uN1Qu3]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

An interesting thread for sure. That's one big old beast of a BGA. Fingers crossed, but i'm sure it will work.

I'm pretty sure it'll work as well. The only thing i was worried about was the scratches on the substrate when i removed the IHS, because the IHS would be touching them when the thing is put back together, but i've looked around and other people have inflicted much greater damage and their card still worked fine after repaste and putting the IHS back on. I'm guessing the whole top of the substrate is a ground plane.

We called the owner and he'll bring his computer in this evening. Here it is all assembled. Sorry for the low quality but all i had around was an old phone.

[mockingbird]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

Nice job Th3_uN1Qu3, as usual...

You should purchase stencils for the RAM...

[Th3_uN1Qu3]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

I have all of them. Two sets actually. But i have not encountered bad VRAM so far, not even once.

I know you're all interested of the outcome... it was... a SUCCESS. Card ran hotter under FurMark than i'd like (peaked at 93C till the fan kicked in at full speed, then stabilized at 89), but as far as i've read from reviews, that's its "normal" operating temperature, and in games it usually runs around 10C lower than FurMark. I have recommended to the owner to install EVGA Precision and set the fan to 100% when gaming, and that's about it.

I've read that sanding off a bit of the edges of the IHS (the side that goes on top of the substrate) would lower temps, because the die is a bit far from the IHS by default, but i'm not getting paid to fix nVidia's fabrication mistakes. It was barely worth reballing this card, let alone perform further mods. I'm just happy that it worked.

[mockingbird]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

I hear you... We've all gone through those "break even" jobs that we're just glad we didn't lose money on in the end.

Another trick is to hack the fan speed temperature curve... Used to be able to do this on older Radeon cards, but I haven't seen a utility to edit the newer BIOS versions yet.

The newer cards run much much cooler. I have a Radeon 7770 that idles in the 30s and maxes out in the 60s. A lot faster than the 4890 too, eventhough it has lessers specs.

[Agent24]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

I have all of them. Two sets actually. But i have not encountered bad VRAM so far, not even once.

I think I have a couple of cards with bad RAM... but how do you figure out which RAM chip is bad?

[stj]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

that's the same problem as the ps3's have,
the paste fails under the cap.
most people dont know & just reflow and it fails again.

i allways remove the cap & use AS5 whenever i open a ps3.
nothing wrong with leadfree solder btw, that's just a myth from the xbox360 days to shift the blame from the complete joke of a coolnig system it had.

[Th3_uN1Qu3]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

nothing wrong with leadfree solder btw, that's just a myth from the xbox360 days to shift the blame from the complete joke of a coolnig system it had.

I beg to differ... There's lots of things wrong with lead-free solder, including the fact that it has a higher melting point which drastically increases the chances to fry the BGA when you're resoldering it.

[c_hegge]

Re: Reballing nVidia GTX470 on the Ghetto BGA Station

nothing wrong with leadfree solder btw, that's just a myth from the xbox360 days to shift the blame from the complete joke of a coolnig system it had.

I also disagree. It's a known fact that lead free solder is more brittle than leaded and cracks much more easily. It works well enough if you keep the BGA really cool, but on a high powered GPU, that's not always possible.