Baked Silicon

Nothing of circumstance happened at work yesterday and today. Last night I finished watching Cat on a Hot Tin Roof. This evening, I took another crack at fixing a laptop I’ve had on hand for a while.I kept Krystle’s IBM Thinkpad T40 at my house after my trip to Ruston last New Years. I was not able to fix it as I determined that the onboard video chip had a faulty connection which caused the laptop to lockup randomly and whenever the laptop was bumped in some fashion. As this wasn’t something I was able to fix at the time I sent Krystle a “new” laptop and shelved the broken one until I could fix it. I read about how people successfully repaired the video chip connection with something called a solder reflow in which the chip and board are heated, melting the solder and repairing the connections. The method described involved a heat gun and infrared thermometer. I wasn’t interested in purchasing those items to fix a laptop worth less than $200. Replacement motherboards on eBay were prohibitively expensive so I just stuck the laptop in my closet.On Wednesday I read an interesting topic at [H]ard|Forum in which someone repaired a broken video card, presumably with a chip connection issue, by heating his card in a standard kitchen oven for a couple minutes. I immediately recalled the Thinkpad in my closet with the same problem and was intrigued by the possibility of fixing the laptop with “equipment” I already have.After doing some reading online I learned that others have successfully attempted the reflow fix in conventional ovens, toaster ovens and even skillets. With a possibility of success in mind I decided to give it a shot. At worst, a laptop that only works when you don’t touch it would not work at all. I spent a good portion of this evening tearing down the laptop. I open up laptops somewhat frequently but I seldom have to gut them like I did tonight. With the motherboard stripped of everything that could be removed, even stickers, I set it up on a cookie sheet. I set it off the metal surface with three little balls of aluminum foil. I was careful to rest the foil on bare areas of the board away from bunches of little circuits. I set the board in the oven preheated to 425 degrees for five minutes. I determined the time and temperature from various estimations and solder melting points I read online. I watched the board through the five minutes just in case of some sort of catastrophe. I never saw any solder appear to be melting so my first thought was I didn’t leave it in long enough.Later after removing the motherboard and letting it cool, I started to reassemble the laptop. I first connected just the display, keyboard and battery to confirm the computer would still POST. It did boot so as I was putting it back together I at least knew I did not fry the thing. It took over an hour to fully reassemble the laptop. I was on the phone with Krystle through a good deal of the process although I was not able to give her much of my attention. I had not documented which screws went where to it took a bit longer than it could have to get the Thinkpad back together. I turned it on a couple times during the job to make sure I didn’t screw anything up.There was no operating system installed so when I was finished I booted a formatting tool from CD and did a zero wipe and format of the hard drive to see if the computer could remain working for an extended period. After that completed successfully I booted a Windows XP installation CD and tapped the touchpad repeatedly while it loaded files. Normally such activity would promptly lockup the computer but again there were no problems. I also installed Windows 7 RC without incident.Following the installation I fooled around with the laptop for a while and still no lockups. I am typing this entry on the resurrected Thinkpad right now, something I would never have been able to do. Keying 750 words is the most substantial stress test I wish to carry out at present but so far it appears baking the motherboard actually worked, which is perfectly logical and astonishing at the same time. I’m quite pleased with myself just now.

Comments are closed.