Reflow using heat gun - black & decker

[fddizon]

hi,

does anyone here uses black and decker heat gun to reflow gpu?
the heat gun has temperature adjustments, and 2 fan speed adjustments.

i am reflowing a gpu of a lenovo T61. graphics display is garbled when turned on.
do have any idea why it gets overheat? fan and vent is clean

regards and thanks for the help
fddizon

[luke10050]

Re: Reflow using heat gun - black & decker

it uses an 8 series mobility chip right? it may work or it may not... you need to get the underside of the bga to about 240 degrees, but not over about 250 or you will fry it... personally i stuck my laptop with a similar gpu in a toaster oven... worked wonders

Edit: oh and you also want to use flux, im not sure what type, i just use a cheap paste flux, melt it under the gpu and go from there. i think another member might be able to fill you in on the specifics. but getting the right temperature is hard... my reflows with a heat gun usually lasted for about 4-5 days.

[kaboom]

Re: Reflow using heat gun - black & decker

do have any idea why it gets overheat? fan and vent is clean

regards and thanks for the help
fddizon

Did they pull an XBOX 360 and keep the fan off until it's way too hot?

You may be able to find a switched 5V supply and hardwire the fan. Assuming it's a 5V fan...

[dj_ricoh]

Re: Reflow using heat gun - black & decker

i`m up for 40 from 60 MB stuck in to the oven and 10 come back and 5 from that 10 never make it the second bake :-S

[luke10050]

Re: Reflow using heat gun - black & decker

i find it works well if you can control temperatures well

[senchire]

Re: Reflow using heat gun - black & decker

Speaking of heat guns, there are few problems which you will face when doing some tricky things with them (we all know they are piece of crap for this work but nearly all try it in the begin).
2 main problems :
1st Low heat area (making some special attachments won't work because you will have in middle 200C and on ends 160C)
2nd Fast rising temp speed (biggest mistake in reflows doing it fast)

Even if you can control the heat (here i mean when you can set which temp you wanna, its still not even on all sides (most cause of wraps with board's, and ofc when reflow then fail its simple "board wraped and few balls couldn't get to the board")).
You can always try, i did few reflows with them. 4/5 came back in 2 weeks (sometimes they lasted for months pure luck).

[momaka]

Re: Reflow using heat gun - black & decker

I've done reflows with a heat gun on some desktop graphics cards (ATI Radeon 9700s) with leaded solder, and it has worked great. I used one of them for heavy gaming for about 5 months and it still works fine.

The only time I used my heat gun on a lead-free graphics card was to remove some bad RAM chips from a 7600GT. 1 of the 4 RAM chips was good, but the others were bad. So if anything, at least I know the heat gun is capable of reflowing without killing the chips if done right.

Normally with the heat gun, I start with the low heat setting, slowly heating the board area under the chip I want to reflow (to do that, I keep the heat gun fairly far away from the board and slowly bring it in closer and closer to the board). Once the bottom side has been heated for a good few minutes, then I move over the top of the board where the chip is and heat again on the low setting. Heat for a few more minutes, then move under the chip again and start on the high setting keeping the heat gun somewhat far from the board and slowly bringing it in again. Heat for a few minutes, then do the same with the top, but only for a minute or two at the most and never bring the heat gun closer than 5 cm / ~2 inches from the chip.

[senchire]

Re: Reflow using heat gun - black & decker

Doing it with heat gun is more luck then skill in my eyes.

[momaka]

Re: Reflow using heat gun - black & decker

Doing it with heat gun is more luck then skill in my eyes.

True. But with temperature probes on both sides of the board, you may actually be able to achieve something. Of course, provided the board isn't really big or really thick - for those you just need a proper BGA station as heat control is really important. But for small boards like graphics cards, a heat gun reflow actually works most of the time.

[senchire]

Re: Reflow using heat gun - black & decker

Actually you can do reflows on big boards if you got a SMD rework station. I did more then 10 of them so. You only need more TC-s on the top side, on each corner.

[jimmyplumb]

Re: Reflow using heat gun - black & decker

This video on Utube is a very good tutorial on reflows.& well worth watching

http://www.youtube.com/watch?v=HEV43byTP9I

[senchire]

Re: Reflow using heat gun - black & decker

Yep it is, but he isn't doing it with a hg b&d :P.

[jimmyplumb]

Re: Reflow using heat gun - black & decker

My first attempt at reflows was with a heat gun same as a B&D
I bought a cheap drill stand & used that to give me more control over the temperature & fabricated a nozzle out off 1/2"fi x15mm compression coupling to give me more precise control & it did the job until I could buy a proper hot air station