How to avoid damage when trying to reflow this laptop graphics chip

[Kahenraz]

I am trying to revive an IBM ThinkPad T41. The laptop boots but there are lines and pixel snow on the display when powered on. I am confident that the screen itself is fine. From my research, this laptop is known to have an issue with the video card failing due to cracked solder joints.

I have already ordered a replacement motherboard so this is just an exercise for experimentation.

The GPU uses an older style package that is not modern flip-chip. The memory is also adjacent to the GPU. It was released around 2001 so I don't think it uses ROHS solder.

I am planning to reheat the board from below and then apply heat from above with a hot air station after doing my very best to get some no-clean flux under the chip by dripping it in from the side.

Given the age of this board, what are temperatures are recommended for reheating and for reflowing the solder? I want to try and avoid damaging the board further.

[coromonadalix]

Normally  you would reflow the chip by hot air,   but in some cases, like the nvidia video card chips who had theses problems ....

The best method i think would be to protect all the surrounding component from excessive heat  by a kapton tape,  or you coud use some peel off foam,  you apply it on all the surrounding parts, let it dry,  and you could put a tape over the parts,     you need to keep the parts from moving when heating ... the air flow could be strong ... the white connector can melt ??

And you remove the video processor chip ...  not sure the 2x memory chips  will move too ??   and you reball the pga pins on the pcb and reball the video processor ...  and put them back together ...

You have many videos on youtube

[perieanuo]

hi,
I resoldered thousands video chips on a metcal machine, never had a T41/T60 ...
just press the video chip with your thumb really hard and start the pc
I really doubt it's the video chip this time

[perieanuo]

for reflow look here https://www.okinternational.com/File%20Library/Metcal/Resources/White%20Papers/Metcal-Profiling-for-successful-BGACSP-Rework-White-Paper.pdf
BUT imho look for lcd cable problems and lcd itself
the vga output looks ok? if vga chip starts to develop bad soldering, sometimes vga out also becomes problematic
don't forgot, thumb test never fails
if you resolder, prepare a good flux also
personally, I had best results with 220-240 degrees C on top side (chip side) and 180-200 bottom side, but I had that 26k$ reflowing machine, if you use a 100$ bga reflowing station, it's dead in the woods

[Kahenraz]

I've always had very little success with kapton tape (the air just blows around and underneath it).

What's this about peel off foam?