HP G62 Reflow Problem

[AndyM]

Have a HP G62 in that I reflowed the graphics card on 2 days ago. All was working fine, had the laptop on for a fair few hours after removing all the crapware associated with a "I'm from Microsoft and your computer is infected" scam. Today, I installed BitDefender, and was running a full system scan prior to returning the laptop to the client tomorrow. A short while after the scan had started, I looked up and saw a black screen. Pretty sure the graphics has the same problem.

The reflow consisted of using a heat gun at 220 deg C, for 8 minutes over the board, concentrating on the VGA chip.

What would you do? Re-attempt, or just write it off as uneconomically repairable?

Edit: HP G62, AMD version

Andy

 

[JustInspired]

Reflows are notoriously unreliable. Re-balling is the the way forward apparently.
We have used these guys in the past http://www.tradelaptoprepair.co.uk/

 

[Larry Sabo]

The reflow consisted of using a heat gun at 220 deg C, for 8 minutes over the board, concentrating on the VGA chip.

I doubt that would have been sufficient, especially if you didn't pre-heat the board to around 180C and given that lead-free solder melts at 217C. What flux did you use? Unless you do a lot of these, I'd suggest referring it to a shop that does. Re-balling a new chip is much preferred to re-flowing, but it's worth a try if the GPU is fairly recent (2010+).

 

[phaZed]

Agree with the others.. reflowing is a dodgy process at best. Larry is right, you probably didn't get it hot enough. You should get it to around 235c with a max of 245c to get good "wetting" from the solder reflow.

 

[AndyM]

I think I'll do some practising on an XBox360 that I've got sitting around. I've not done a lot of soldering/reflows at all. Used to outsource them to a local guy, but he shut shop, and the was no one to replace him.

I do have some liquid flux. Can't tell you the exact specs as it's at work, and I'm at home.

Andy

 

[Larry Sabo]

I forgot to verify where you measured the temps, as you say you set the heat gun for 220C. The temps that PhaZed mentions are spot on, and are measured with the T/C ball touching the MB right beside the GPU. The ramp rate should also be between 1 and 3C/second and it's a good idea to pre-heat the MB for some time to vet the moisture, to avoid pop-corning (although it's less of a problem with hot air vs IR).

Edit: I'd also say that without an IR bottom heater to bring the board temps to 180C without top hot air, it's going to be waste of time.

 

[AndyM]

Thanks Larry (and PhaZed ). The heat gun has a temperature setting on it (bottom right pic), and it's the temperature control that I'm using. I do not know how accurate it is:

Product info: http://www.evolutionpowertools.com/uk/build/hdg200.php

Gun was held maybe an inch and a half above the graphics chip, by hand. Fan speed was set at 50%

I am thinking of getting a laser thermometer that can be held on a tripod so that I can get accurate temp measurements during the whole process.

Andy

 

[Larry Sabo]

I haven't found the laser thermometer I have to be very accurate. It is affected by surface emissivity too much. A thermocouple (Omega are best) and a temperature-reading meter are more accurate.

 

[Krynn72]

We used to do lots, and lots (and lots) of reflows on HPs, including G62s. Frankly unless you reball it, I'd guess you're going to keep getting that same result. We have a proper reflow machine with heating base and ramping temperature control for the top heater, and I'd guess that more than 50% of the repairs came back within 90 days, with more of them coming back sometime after that. Probably 80% of them didn't last a year.

We do very few reflow repairs now, mostly on non-hps which usually work fine with no returns.

 

[NJW]

What would you do? Re-attempt, or just write it off as uneconomically repairable?

It's too much of a lottery. I have done perhaps a dozen, various makes and models (including a PS3). Only one has lasted over six months and I no longer bother trying. I prefer to offer to put the hard drive in an external enclosure and dispose of the machine for parts (screens, keyboards and, occasionally, plastics are worth reusing).

It's a fundamental design problem and no amount of hacking is really going to solve it. Proper reballing may be a good longer-term solution, but cost and availability here means that it's out of the question. Few of the affected laptops are worth it, anyway. I do encourage clients with one of the usual suspects to have the fans cleaned regularly, prevention being better than cure, and that has turned out to be a better policy.

 

[Matthew Bradley]

I can assure you that heat gun didn't properly reflow the gpu. It has to be heated underneath also and the solder, when liquidus, must soak for a minute or so to burn off any oxidation. Back in its hay day, we would do about 10 - 15 a month. It became almost comical. I thought we were through with these then Dell made the M5010. Why don't these companies learn?