is PCB bump did not make a serious problem? gtx680 Graphics card

[julianmustofa]

hi everyone..

i have a dead graphics card (gtx680)
the gpu chip was faulty and shorted to ground (VRM still intact btw)
so i remove the chip and just realize that bga pad underneath the gpu chip is kind of bump or swollen.
and suprisingly the pcb still good. no short circuit and i checked every pad and all still have good connection at every rail they should be

so i just wonder what is serious problem from the pcb bump like this that i may still didnt know this time?
or maybe some of you have been experiencing with effect from this kind of damage?

(the chip it self was dead btw) and i dont have working gpu chip rightknow. maybe soon i'am gonna replace this chip and tested it

thanks

[DynaxSC]

Re: is PCB bump did not make a serious problem? (Graphics card))

Hi, probably you overheated the board when taking off the GPU, and thats the reason for this demage. Some vias will be probably demaged, you can try to solder a new GPU, but the chances that it will work are almost zero, also because the area is no more flat, unfortunately not repairable. Too much heat, maybe also too less solder paste. Apply so much solder past, that all the space between GPU and board is filled. Best is to apply from one or two sides, when preheating the board, not to enclose air inside. You should monitor the temperature with a fast sensor directly at the board and GPU egde, and not go beyond 270 C - unleaded tin used in professional production sites becomes liquid at 254 C. Preheater must also have not more than 200-230 C, dependent how far away the heater is from the board . Hotairgun you can go 380-420 C, but reduce immediatelly when board achieves 260-270 C and the GPU is loose so the temperature does not rise any more. To check tip the GPU slightly from the side, never from the top, so not to brake pads, when still not all balls are liquid (leverage effect). You should also use a good nozzle slightly larger than the GPU, with a drilled plate inside distributing the hot air evenly. Cheap nozzles w/o this diffusor heat in the center much more than at the edges. Also a fixed arrangement is good, so to have hands free.

This effect can also be due to some humidity (water particles) enclosed in the board materiał, so if a board wasn't used long time, its better to leave it first on the preheater with moderate 120C temperature for 12-24 hours to get out the water particles out of the board w/o demaging it. Same procedure applies to any chips, when we want to go sure they will not be destroyed.

This is a matter of practise, when I started I made the same with several boards, before I got it how to do this.

[dicky96]

Re: is PCB bump did not make a serious problem? gtx680 Graphics card

I agree that PCB is destroyed. I can also concur this sort of damage occurs with too much heat applied locally and not enough heat applied to the PCB in general

Out of interest what did you use to desolder the GPU?

To have a reasonable chance of success I would suggest you use a temperature controlled IR preheater larger than the PCB you are working on - set the preheater at 200C to heat-soak the entire PCB and then use either a IR top heater with proper profile to heat the GPU from above, or a 3-zone hot air plus IR preheater BGA rework station with hot air nozzles above and below the GPU (both nozzles must be larger than the GPU) and as mentioned above the perforated type nozzles to give an even heat spread.

Then there is the matter of getting the profile right for your rework station and the PCB. This takes some practice and you can expect to destroy numerous boards in the process of trial and error before you learn how to do it. Trying to do this manually without a preprogrammed profile is a journey to nowhere IMHO - and I have tried (and published videos of the results) to prove this.

I use the 3 zone hot-air plus IR preheater system myself (LY G720) and I am still quite capable of producing the same sort of damage as you show in your photo if I get the profile wrong - and sometimes I do because the correct profile will depend on the thermal mass of the PCB, so there is an amount of guess work and experience involved and when you get it wrong there is very little you can do about it. Even if you get very lucky and get it right using manual equipment on one PCB, you can't get repeatable results this way and will likely destroy the next one.

I know others here have very good (better than me) results with fully IR rework stations but this may be as much to do with them having more experience than with IR being better than hot air. Get which ever type you prefer and learn how to use it. Price is always a factor but don't use it as your main factor or you will be unlikely to get the reuslts you want. i.e - don't buy something just because it is the cheapest, do some research.

[julianmustofa]

Re: is PCB bump did not make a serious problem? gtx680 Graphics card

Hi, probably you overheated the board when taking off the GPU, and thats the reason for this demage. Some vias will be probably demaged, you can try to solder a new GPU, but the chances that it will work are almost zero, also because the area is no more flat, unfortunately not repairable. Too much heat, maybe also too less solder paste. Apply so much solder past, that all the space between GPU and board is filled. Best is to apply from one or two sides, when preheating the board, not to enclose air inside. You should monitor the temperature with a fast sensor directly at the board and GPU egde, and not go beyond 270 C - unleaded tin used in professional production sites becomes liquid at 254 C. Preheater must also have not more than 200-230 C, dependent how far away the heater is from the board . Hotairgun you can go 380-420 C, but reduce immediatelly when board achieves 260-270 C and the GPU is loose so the temperature does not rise any more. To check tip the GPU slightly from the side, never from the top, so not to brake pads, when still not all balls are liquid (leverage effect). You should also use a good nozzle slightly larger than the GPU, with a drilled plate inside distributing the hot air evenly. Cheap nozzles w/o this diffusor heat in the center much more than at the edges. Also a fixed arrangement is good, so to have hands free.

This effect can also be due to some humidity (water particles) enclosed in the board materiał, so if a board wasn't used long time, its better to leave it first on the preheater with moderate 120C temperature for 12-24 hours to get out the water particles out of the board w/o demaging it. Same procedure applies to any chips, when we want to go sure they will not be destroyed.

This is a matter of practise, when I started I made the same with several boards, before I got it how to do this.

I agree that PCB is destroyed. I can also concur this sort of damage occurs with too much heat applied locally and not enough heat applied to the PCB in general

Out of interest what did you use to desolder the GPU?

To have a reasonable chance of success I would suggest you use a temperature controlled IR preheater larger than the PCB you are working on - set the preheater at 200C to heat-soak the entire PCB and then use either a IR top heater with proper profile to heat the GPU from above, or a 3-zone hot air plus IR preheater BGA rework station with hot air nozzles above and below the GPU (both nozzles must be larger than the GPU) and as mentioned above the perforated type nozzles to give an even heat spread.

Then there is the matter of getting the profile right for your rework station and the PCB. This takes some practice and you can expect to destroy numerous boards in the process of trial and error before you learn how to do it. Trying to do this manually without a preprogrammed profile is a journey to nowhere IMHO - and I have tried (and published videos of the results) to prove this.

I use the 3 zone hot-air plus IR preheater system myself (LY G720) and I am still quite capable of producing the same sort of damage as you show in your photo if I get the profile wrong - and sometimes I do because the correct profile will depend on the thermal mass of the PCB, so there is an amount of guess work and experience involved and when you get it wrong there is very little you can do about it. Even if you get very lucky and get it right using manual equipment on one PCB, you can't get repeatable results this way and will likely destroy the next one.

I know others here have very good (better than me) results with fully IR rework stations but this may be as much to do with them having more experience than with IR being better than hot air. Get which ever type you prefer and learn how to use it. Price is always a factor but don't use it as your main factor or you will be unlikely to get the reuslts you want. i.e - don't buy something just because it is the cheapest, do some research.

Sorry all for such a long time to reply this because i didnt notice it

I use hot air to remove the chip. And i use custom made preheater and its arround 200°C at max
And i also did dry this board with 90° for an our

TBH this is my first time i remove such a large gpu chip
But iam sure this whole damage its form someone that (maybe) reflow the chip and overheated. I found a pcb bump at the back of the pcb (gpu chip area) before i remove the chip.
And after i look at the gpu chip price i think i change my mind because its too expensive for low succes rate because this bump look not promising just like you guys said

[DynaxSC]

Re: is PCB bump did not make a serious problem? gtx680 Graphics card

Hi, recently I have made just for fun some tests on a similarly destroyed motherboard (not my achievement), if such bublles are possible to remove. And, in fact you can do it, heating the board to some 200-250 C, and applying then mechanical force from both sides, to make the board flat again. The pcb becomes quite flexible in such temparatures, so it's easy possible to do some shape modification to it. So you would need to construct some kind of tool - eg. 2 aluminium plates 2-3mm thick, and screw them together from both sides under temperature, and let it cool down when screewed together, only small issue is the caps area under the GPU, which needs to be omitted. Its possible like that to remove the bubbles. Unfortunately heating it again leads the bubbles to arise again, but they might be smaller, dependent on the material of the pcb. You can aslo try to press down the bubbles, eg with a wooden tool like the other end of a brush, when cooling down the board. You might try and play around with it, but probably this will be not of success, when attempting to place the BGA chip back again. But it's funny to try

[piernov]

Re: is PCB bump did not make a serious problem? gtx680 Graphics card

A delaminated PCB is a dead PCB, can't fix it. On top of it never being flat again, thermal expansion will make it unevenly expand and cause deformation, and most likely inner traces and vias are damaged as well.

[julianmustofa]

Re: is PCB bump did not make a serious problem? gtx680 Graphics card

Hi, recently I have made just for fun some tests on a similarly destroyed motherboard (not my achievement), if such bublles are possible to remove. And, in fact you can do it, heating the board to some 200-250 C, and applying then mechanical force from both sides, to make the board flat again. The pcb becomes quite flexible in such temparatures, so it's easy possible to do some shape modification to it. So you would need to construct some kind of tool - eg. 2 aluminium plates 2-3mm thick, and screw them together from both sides under temperature, and let it cool down when screewed together, only small issue is the caps area under the GPU, which needs to be omitted. Its possible like that to remove the bubbles. Unfortunately heating it again leads the bubbles to arise again, but they might be smaller, dependent on the material of the pcb. You can aslo try to press down the bubbles, eg with a wooden tool like the other end of a brush, when cooling down the board. You might try and play around with it, but probably this will be not of success, when attempting to place the BGA chip back again. But it's funny to try

I get your idea. But the broken via inside pcb still questionable