X31 ball grid array reflow?

[gho]

Hello fellow thinkpad users,

I have a used X31 that started to crash randomly and showed the BSOD. I fixed the latter problem with a firmware update for the controller, but the thinkpad continues to crash occasionally when mechanically strained. I think the cause is a broken solder joint somewhere on the mainboard somewhere under the letter U of the keyboard. I disassembled the machine and saw these chips attached to the mainboard with ball grid arrays. I am not sure, if the point of failure is located around this area, it may also be the ram slots. Right now i am typing on that thinkpad. I put two layers of cloth into the RAM department to put some pressure on the mainboard, a move, that seems to stabilize the issue, but surely this is not a permanent fix.

So I searched the web and found this forum with it's information about the heat gun technique. I am bit hesitant to apply this technique, because it seems to be a bit too vigorous for my taste and I am a bit afraid of damaging the mainboard completely. Are there other, more gentle ways of reflowing the grid (if it is the grid in my case).

I saw an approach using tea-lights.
http://geektechnique.org/projectlab/726 ... ard-repair
What is your opinion on that? However, the melting temperature of solder is much higher than the burning temperature of ethanol.

Thanks in advance.

[rkawakami]

Welcome to thinkpads.com!

A professional reflow, preferably using an infrared heat source, can solve most BGA bad contacts but it's not without some danger. The homebrew method of using a heat gun, with some sort of method to measure the temperature being applied, is somewhat more risky but it has been successfully done. There have also been some reports of that method totally trashing the motherboard. I guess it's a matter of how "badly" the system is working right now. If it's unbootable, then you have no chance of making things worse, do you . If it's still working with a shim, then the reliability of the system is in question, but you also may make it permanently bad if the heat gun approach fails. If you are already prepared to pay good money for another working motherboard, then you have two options:

- use a reflow service (like the one advertised at the top of the page)
- or try fixing it yourself

However, before even attempting this fix, you should make sure that the problem is with whatever BGA package you think is bad and simply not a bad solder joint on the memory slot(s), which may be easier to repair.

[gho]

Thanks a lot for the reply! For now the shim in the RAM compartment is working fine, but I think I will reheat the pins of the memory bank to rule a faulty ram slot out. On occasion I got memory related beep codes, but there is no visible crack though. If the reheating fails a professional service is the way to go I guess.