Testing a BGA - Good or Bad?

[speedypro]

It takes time to get a laptop naked just to get to the motherboard. It takes flux, epoxy remover, heat and electricity just to remove a chip in which I'm getting tired of doing. Is there a way to test BGA chips? I don't mind taking them off just to test.

Nvidia Chip off an HP G6000:

[DJduck]

Re: Testing a BGA - Good or Bad?

The only thing that you can probably do is apply power and see if it gets hot.

[sasser]

Re: Testing a BGA - Good or Bad?

Good thread. I was also get problem to detect either chip bga is ok or not. When apply power the bga gets hot. Sometimes not because some solder balls crack or oxidiation under chip and cant got current. What to do just try and error.

[thesloc]

Re: Testing a BGA - Good or Bad?

Impossible.

Only way to know is to first do a reflow.

Aside from plugging laptop into external monitor first after checking other components such as CPU and RAM since they give almost the same symptoms as a bad GPU.

[senchire]

Re: Testing a BGA - Good or Bad?

You could do a OHM messure after reball still you have to reball it :P. (and sometimes it shows good rating and its crap, sometimes shows crap rating its good you can never be sure -,- ).

[sasser]

Re: Testing a BGA - Good or Bad?

Want to know from experienced you all. How many time bga can reball reflow? Or if bga not become dark green or bubble the bga still ok?

[senchire]

Re: Testing a BGA - Good or Bad?

You mean bubble on the chip (most likely popcorned or burned)? When i was without equipment i did a lot reflows (4-5). As long i was in the temp range the chip didn't burned or corned and was working.
The more heating cycles the BGA/joins get worser. Reballs dunno when ever i do it, it never goes bad (customers never came back with that problem).

[thesloc]

Re: Testing a BGA - Good or Bad?

sometimes the chip is just bad, even after successful reball or reflow.

but they do sell the chips with leaded solder balls on them on eBay

[DJduck]

Re: Testing a BGA - Good or Bad?

Just like the nvidia 6, 7 and 8 series. They still die after a reball.

[speedypro]

Re: Testing a BGA - Good or Bad?

I hear what you all are saying but it's time consuming to reball and the chip is already bad. I just need a way to test before I do the reball.

[thesloc]

Re: Testing a BGA - Good or Bad?

There's no easy way.

[speedypro]

Re: Testing a BGA - Good or Bad?

There's no easy way.

Ok. Do you know what is this?

[dileep.soft]

Re: Testing a BGA - Good or Bad?

We will Know by Checking Hsync and Vsync there must be 0.7v to 1v present if not check the output from GPU ...

[thesloc]

Re: Testing a BGA - Good or Bad?

Ok. Do you know what is this?

That's using expensive hardware and software.

[thesloc]

Re: Testing a BGA - Good or Bad?

We will Know by Checking Hsync and Vsync there must be 0.7v to 1v present if not check the output from GPU ...

HMMMMMMMMMMMM interesting.

Can you please elaborate on this.

[jtamad44]

Re: Testing a BGA - Good or Bad?

if you guys want a long term fixed, change the chip with a new one.. 2 to 3 years is long enough before the client comes back for another new chip.

if can reball the old chip but it would last only 6 to 8 months.

[robrock1]

Re: Testing a BGA - Good or Bad?

hello, i also recommend a new chip but iam doing a lot of reflow with hot air only, even the chips with the red glue, i remove the glue and i reflow, after years of doing it i have a good sucess rate sometimes it even last longer than one year, iam surprised in the beginning i did it wrong it lasted only some days or a month, i also had this dv9000 machine the customer always brings it back after 5 month, i reflow it again, it last for another 5 month, did it like 4 times now, still working.

[spidey]

Re: Testing a BGA - Good or Bad?

hello, i also recommend a new chip but iam doing a lot of reflow with hot air only, even the chips with the red glue, i remove the glue and i reflow, after years of doing it i have a good sucess rate sometimes it even last longer than one year, iam surprised in the beginning i did it wrong it lasted only some days or a month, i also had this dv9000 machine the customer always brings it back after 5 month, i reflow it again, it last for another 5 month, did it like 4 times now, still working.

Can you explain your reflow progress ? what is the point of this high success rate ? i always reball, or change. But if it lasts 5months or more, why not.

[marcellodj]

Re: Testing a BGA - Good or Bad?

heatgun it at 100c, if it come back to life, is a bga issue: at your choice reball or replace with a new one (right way).

[robrock1]

Re: Testing a BGA - Good or Bad?

First its very important to remove the glue completely either with chemicals or with a very sharp and thin knive which can go under the chip, after you remove the glue use alcohol and clean the whole area that there is no remaining pieces of glue.
Then i put some flux around, you dont have to use too much, the balls will swim away, so you use the right amount of flux all around the chip. Then i use 2 heatguns, one from below, the other from the top, i heat the board up to 160 degrees before i start heating the chip. I use infrared thermometer to check temperature. Depending on the chip, the heat has to go up to 226 degrees, slowly of course. When the heat is right, i tip on the chip to see that its liquid so it moves, then i stop and imedately cool the board down with a fan. After that cleaning with alkohol, renew thermal paste, clean fans, etc.