My IBM Thinkpad T41 developed the symptoms of a the GPU (Graphics Processing Unit) failures commonly reported on the laptops. This included freezing screens which for me occured during start-up of both Ubuntu Linux and Microsoft Windows XP. I suspect that the GPU would heat slightly during start-up and the BGA contacts lifted once a certain temperature was reached. This caused the froze display while the computer still apparently loads up. Because this happened a month before Spring quarter 2009 at RIT ended (I was busy with school and traveling with RIT Crew) there was no time to fix it.
Now at home, I decided to tackle this problem since I had absolutely nothing to lose... trashing a useless computer was about the worst that I could see happen. I decided to attempt a solder re-flow as opposed to a professional replacement of the solder since it was much easier. The latter would be the last effort since it was much more delicate (involves taking the GPU off of the board and placing it exactly back in place). I do not own a heat gun and inquired to my local amateur radio clubs to borrow one. Many responded wanting to help and I decided to borrow one from a member of the Police Amateur Radio Team of Westford (P.A.R.T), a club I am very active with.
Acquiring the heat gun which was only half the power of those seen on most youtube solder re-flow videos, I set out to attempt the fix. Using the disassembly manual from IBM I started taking the Thinkpad apart.
Removing the hard drive.
Under the keyboard which was easily removed.
Separating the LCD monitor from the motherboard and main chassis was easy and revealed the antennas for the blue-tooth and WIFI cards (the black and Gray wires coming from the monitor). The antennas were mounted vertical on the left portion of the monitor.
The motherboard after an hour of carefully removing parts and organising screws.
Pentium M processor carefully removed and put in an antistatic bag. I wanted to prevent unneeded heat from being applied to the chip.
The GPU which best to my knowledge has one or more lifted contacts under it.
The plastic components must be carefully shielded from the heat. I also warmed the whole board up evenly for several minutes on the underside of the board and eventually the top of the board to prevent excess stress from temperature differences... a crack in a board trace means GAME OVER! After the board was sufficiently warm I started to apply concentrated heat to the GPU. In several minutes of circular motion 1-2 cm above the chip, I heated it up enough to flow solder. If I had an infra-red thermometer I could tell exactly when this occured, unfortunately I do not. Since the heat gun was 475 Watts I could get fairly close to concentrate the heat. I knew this only because I used scrap PC board to test melting solder prior to attempting this. If you are using a higher wattage heat gun this could result in destroying the GPU!
After the heat process, I began backing the heat gun away several inches and slowly cooling down the board. It is severely important that the board is not touched or moved when it is hot enough to have melted solder. One of the components could move and cause more problems. Again I took temperature differences into mind to prevent any other failures. About 3 minutes later I turned the heat gun to the cool setting and blew cool air on the board. Two or three minutes after that I let the board sit for about 10 minutes prior to touching it. I assembled the computer and the moment of truth arose.
As you can see, the solder re-flow worked! I actually wrote this web-page with the Think pad T41! So what did I learn from this project? First of all, now that I understand micro-controllers and other digital circuits much better and am working with more static sensitive circuits an ESD (Electrostatic Discharge Safe) workbench is needed. I also should acquire a heat gun to worth with SMD parts as well as use shrink wrap. Last but not least, anything is possible and if I said I wasn't nervous that this wasn't going to work I would be lying!
