Pre-balled GPU versus reflow

[sparker1]

I don't have reballing equipment but have done a few successful reflows with a heat gun and temperature control. I see Ebay sells GPU's that have been "pre-balled" with new solder balls. I was wondering if these could be a viable option to reflowing without having IR stuff etc. It's a cheaper option than buying a new MB......if it works. I can see a few problems with it i.e. I would be basically doing a reflow but on a re-soldered GPU and there may not be any advantage over a normal reflow. Then again the solder would not be suffering the same problems as the original manufactured item. Has anybody tried it?

[Th3_uN1Qu3]

Re: Pre-balled GPU versus reflow

It's a huge pain in the ass either way. To install a pre-balled chip you'll still need to do the hardest steps of BGA rework, which are taking off the old chip and cleaning the board. And if you don't melt all the balls under the new BGA chip at the same time, you'll break it. It's almost impossible to heat the chip uniformly with a simple heat gun.

To add to that, in most cases you'll have to reball anyway the chips that you get pre-balled, because the Chinese tell you their chips come with leaded solder, but once you get the chip you easily figure out it's something else (it doesn't shine).

Why? Well, attempting to solder a lead-free chip with a heat gun... well, if you manage it from the first 50 tries, let me know. Just throwing some numbers out: Lead-free solder requires 235-240C to fully melt. At 250C the BGA blows up and shorts internally. The margins are very very tight. With leaded solder you at least have a higher chance of success.

[sparker1]

Re: Pre-balled GPU versus reflow

I was thinking along those lines too. It is not a worthwhile option I guess. One day I'll lash out and buy an IR reball station because the GPU is always a source of MB failure.

[sasser]

Re: Pre-balled GPU versus reflow

some bga we got from online market need to reball again. i dont know why . when ask reseller they dont know what type solder balls use, any body know which store have good bga.
sparker1 from my experience u can buy reball kit but the most important is to make sure the mold and design is quality. fit not loose when u close the top cover stencil. if not fit u become headache to allign because some ball can stick together when not in good position

[sparker1]

Re: Pre-balled GPU versus reflow

Good advice. Thanks Sasser

[senchire]

Re: Pre-balled GPU versus reflow

I always reball my GPU, and rarely have faulty ones. Stencils aren't expensive and its easy after few tries.
And doing reball with an HotAir gun is suicide. At least get a Preheater and rework station because you need a lot temperature control in this job, and of course get some good flux it makes this job a lot easier. Good luck.

[sasser]

Re: Pre-balled GPU versus reflow

Senchire i also agree the preheater help a lot. I have honton ht-1212 which help me melt the solder ball .just set up temp to 220 and put on prehear then look till solder ball shine n melt

[senchire]

Re: Pre-balled GPU versus reflow

Yep when doing reflows people should know that PH is doing more then 70% of the job. Top Heater is just for finishing it up .