Baking the Motherboard

[DerStrom8]

Hey guys. I'm new here, so hopefully I'm putting this in the right place.

First off, a little introduction--

My name is Matt. I have worked with electronics for many years, both as a hobby and for a job. I am currently working as a computer and electronics technology lab assistant at a university in Boston. I am a huge DIYer--I prefer to do everything I can on my own, and most of my projects have a $0 budget. I'm a MacGyver of sorts--I throw things together to try to make something work.

So here's my question:

I recently came across an old HP Pavillion DV2500 laptop with a supposedly fried video card (I turn on the laptop and I get nothing but a black screen). Since the video cards are built into the motherboard, I figured I'd probably have to spend a fair amount of money to replace the motherboard entirely. However, I came across a few bits of documentation saying that this issue (damaged video card) was extremely common in the HP DV series, and that an easy, cheap fix is to put the motherboard into a 400 degree F oven for 10 minutes. Somehow this is supposed to fix the problem.

My question to you is, do you guys think it's worth a shot? The way I see it, if I'd be spending a few hundred dollars for a replacement motherboard anyway, why not try this supposed cheap fix? I wouldn't lose anything if it didn't work--I'd still have a motherboard with a damaged video chip, right?

Anyway, if any of you have ever tried this, how'd it work out? Have you heard of this fix before?

Any opinions or suggestions would be greatly appreciated!

Best wishes,
Matt

[mockingbird]

Here are the instructions I got off of a forum I usually follow:

- Preheat the oven and leave the card 4 minutes at 150ºC
- Up the temp to 230ºC and leave 2/3 minutes at 220-230ºC
- Open the oven door to lower the temp to 150º, close the oven door, leave the card for 3 minutes more.
- Off the oven, leave the door opened and let the card cool naturally for 40 minutes.

Don't forget to take all the plastic stickers and protective covers off the PCB. You can leave the paper stickers on, they'll just brown a little in the oven. If you add liquid flux underneath the chip, you will extend the life of your reflow. If you don't, it will probably only last a few months, if even that.

[DerStrom8]

Originally Posted by mockingbird

Here are the instructions I got off of a forum I usually follow:

- Preheat the oven and leave the card 4 minutes at 150ºC
- Up the temp to 230ºC and leave 2/3 minutes at 220-230ºC
- Open the oven door to lower the temp to 150º, close the oven door, leave the card for 3 minutes more.
- Off the oven, leave the door opened and let the card cool naturally for 40 minutes.

Don't forget to take all the plastic stickers and protective covers off the PCB. You can leave the paper stickers on, they'll just brown a little in the oven. If you add liquid flux underneath the chip, you will extend the life of your reflow. If you don't, it will probably only last a few months, if even that.

Thanks for the reply mockingbird!

This description is quite different from the one I read about. It would be difficult for me to measure the temperature of the oven as it's an antique gas-fired one, no digital readouts of any sort. I suppose I could try to scrounge up a thermometer designed for use within an oven. I appreciate the instructions. I'm sure they'll be a huge help!

If anyone has any more suggestions, I'll be happy to hear them. At least now I have a good place to start.

Again, many thanks!
Regards,
Matt

P.S. By the way, this is one of the videos I found first suggesting the method: http://www.youtube.com/watch?v=jsmlALfEgPg

[DerStrom8]

I just found this video that does essentially the same thing, except it's a lot faster and doesn't require filling an oven with toxic fumes: http://www.youtube.com/watch?v=crJOEGioLTg

Has anyone used the torch technique? Do you have any tips or tricks? Obviously you need to cover up the parts that could melt/burn, and you have to keep the torch constantly moving, but are there any other suggestions?

I might be able to get my hands on a heat gun. Any chance that would work just as well?

I've also been meaning to ask--I have a Weller temperature-controlled soldering iron. It's old, but still gives off really good heat. Is there any way to use that thing instead?

Sorry for all the consecutive questions. I guess I'm a little excited with this project. The guy who handed me this laptop said that if I can fix it I can have it. It's a really nice machine, and if I can get it to work again it might become my main computer. It'll need a few upgrades--RAM, OS, etc--but other than that, i really like the look and feel of it.

Regards,
Matt

[Th3_uN1Qu3]

It's a better idea to use the oven. It lasts between 3 months and an year, depending on your luck. You can pick up a cheapo multimeter with temperature probe for $10.

Also, it is vital to do the following: Make 4 balls of aluminum foil of equal size, around 1-2cm diameter, and put the board on top of those. If the mainboard touches the cooking tray, you'll break it beyond repair, so remember to do this. Board should be put in GPU side up.

[DerStrom8]

Originally Posted by Th3_uN1Qu3

It's a better idea to use the oven. It lasts between 3 months and an year, depending on your luck. You can pick up a cheapo multimeter with temperature probe for $10.

Also, it is vital to do the following: Make 4 balls of aluminum foil of equal size, around 1-2cm diameter, and put the board on top of those. If the mainboard touches the cooking tray, you'll break it beyond repair, so remember to do this. Board should be put in GPU side up.

Thank you kindly th3_uN1Qu3. I had read somewhere about setting it up. I have even heard of people using sheetrock screws, gently screwed in partially to the holes to act as legs. I was planning on using wooden blocks of some sort, since they seemed like they'd be a little more sturdy. I'd be hesitant to use aluminum foil balls because I'd worry that either 1) I wouldn't be able to make them perfectly even, or 2) they'd roll slightly and mess everything up. I suppose if I flattened both the top and bottom it may work though. We'll see what happens.

If I opt for the oven technique, I'll have to acquire an oven that isn't used often and that's in a well-ventilated area. I'll let you know if I can figure these things out.

Cheers,
Matt

[Evil Lurker]

One other bit of advice... getting a board up to reflow temps is hell on electrolytic capacitors, both aluminum and tantalum. I would highly suggest removing all caps other than ceramic if doing an oven reflow.

[DerStrom8]

Originally Posted by Evil Lurker

One other bit of advice... getting a board up to reflow temps is hell on electrolytic capacitors, both aluminum and tantalum. I would highly suggest removing all caps other than ceramic if doing an oven reflow.

Good evening Evil Lurker. Thanks for the reply.

That's why I was figuring it'd be easier and safer to use a torch or a heat gun, since you can easily direct the heat at the video card. Surrounding components and board can be covered with aluminum foil to protect the sensitive parts.

I was getting recommendations here to just use an oven, but between other forums and some of my coworkers, I'm hearing it'd be a better idea to use a heat gun. I'm trying to sort things out here to make more sense since I'm receiving conflicting arguments

To me, it would make more sense to use a heat gun, but I'm wondering who has had experience doing this and what their recommendations are. As I think I mentioned before, I'm a little leery about using my oven (which I use to cook food) to cook a motherboard. I'd prefer that to be a last resort, to be honest.....

Cheers,
Matt

[ratdude747]

Originally Posted by Th3_uN1Qu3

Also, it is vital to do the following: Make 4 balls of aluminum foil of equal size, around 1-2cm diameter, and put the board on top of those. If the mainboard touches the cooking tray, you'll break it beyond repair, so remember to do this. Board should be put in GPU side up.

Noted on the AL balls. When I went to do my 8800GTS reflow, I didn't do that; I put it on a plan sheet of AL foil (so I wouldn't ruin mom's cookie sheet)... and the card lasted 3 months. I did however use a liberal amount of paste flux.

Also, Poly/ceramic caps CAN be left on. Tants sorta Can, and Lytics not at all.

[mockingbird]

How did you stuff paste flux underneath the BGA?

[ratdude747]

Originally Posted by mockingbird

How did you stuff paste flux underneath the BGA?

I put liberal amounts around the edges, and the flux melted and flowed under long before it got to solder melting temperatures.

I will not that when I got it the output had blue artifacts but otherwise sorta worked; when it died, it was 100% dead (computer wouldn't post).

[momaka]

Originally Posted by mockingbird

Here are the instructions I got off of a forum I usually follow:

- Preheat the oven and leave the card 4 minutes at 150ºC
- Up the temp to 230ºC and leave 2/3 minutes at 220-230ºC
- Open the oven door to lower the temp to 150º, close the oven door, leave the card for 3 minutes more.
- Off the oven, leave the door opened and let the card cool naturally for 40 minutes.

Don't forget to take all the plastic stickers and protective covers off the PCB. You can leave the paper stickers on, they'll just brown a little in the oven. If you add liquid flux underneath the chip, you will extend the life of your reflow. If you don't, it will probably only last a few months, if even that.

That's actually the correct method to do an over reflow. However, I would say DON'T preheat the oven (or preheat to no more than 100C) - this is to avoid thermal shocking of the PCB.

And ALWAYS use flux. When the solder is hot and there is no flux, it will start to develop tin whiskers. Usually they are not big enough to cause a short between the solder balls, but they take away from the solder joint between the chip and the board, and that's not good. Also, a cracked joint may not always reflow properly if there is too much oxidation where the solder fractured. That's why flux is vital. It will make the balls nice and shiny. Do NOT over-apply flux either, though - that can make it hard for air bubbles to escape from under the chip.

Originally Posted by DerStrom8

This description is quite different from the one I read about. It would be difficult for me to measure the temperature of the oven as it's an antique gas-fired one, no digital readouts of any sort.

That's fine, you don't need an exact digital readout. Most ovens (even the analog switch ones) are calibrated fairly well. I did some thermal measurements on a an electric toaster oven with an analog switch. The temperature was more or less within +/-5C of the stated temperature on the knob. That's pretty good control IMO. +/- 10C at 230C will be fine.

Originally Posted by DerStrom8

I just found this video that does essentially the same thing, except it's a lot faster and doesn't require filling an oven with toxic fumes: http://www.youtube.com/watch?v=crJOEGioLTg

Has anyone used the torch technique? Do you have any tips or tricks? Obviously you need to cover up the parts that could melt/burn, and you have to keep the torch constantly moving, but are there any other suggestions?

I just tried a blow torch on a motherboard the other day. Its very VERY easy to warp the board and overheat the chip with it. Definitely not a good idea if you've never done a reflow before.

Originally Posted by DerStrom8

I might be able to get my hands on a heat gun. Any chance that would work just as well?

Heat gun is okay, but again, you have to be careful not to overheat the chip.

Most videos on YouTube just show to heat the chip from the top on high setting, but this is NOT a good method. You have to alternate between top and bottom of the chip if you want a good reflow without warping the board (and quickly heating a board from one side will almost always warp the board). The trick to do that is to suspend the board on something so that you have access to both sides of the board where the chip is. At the same time, that something should be able to withstand the high heat. So you may have to build a custom stand for it. Wood is okay. I usually use two long metal rods and clamp them off of the table, then put the board on that.

I actually just did a heat gun CPU socket reflow on a S939 motherboard last week. Socket is now sitting nice and flush on the board, and the balls are much more shiny than before. I did this by slowly heating the board with the heat gun (on low setting, which pushes out hot air at ~200-300C on my heat gun) both from the top and the bottom. Then I added paste flux around the CPU socket. Finally slowly heated the CPU socket again from both sides (first at low setting for a few minutes, then alternating between high and low setting). The whole process took about 15 minutes. For laptop motherboards, you could probably do it in 10 since the board is usually thinner and smaller.

What's tricky about the heat gun is that it's hard to know the temperature of the board without a temperature probe. Ideally, you'll want the board and chip sitting at 230C for about a minute for a proper lead-free chip. Anything less than 220C, and the reflow may not be very good. Anything higher than 260C, and you run a risk of ruining the chip. If you've never done any reflowing, then heat gun is not the best method. Of course, you have nothing to lose if you try (aside from some time). Since this will be your first time reflowing a board, I'd say try to be careful not to overheat the chip. If the reflow doesn't work, try again, this time heating for a bit longer.

All in all, though, I would suggest the oven method. You may have to wipe the oven afterwards, however (if you want the flux smell to be gone). Alcohol works great. Not sure about chlorine-based wipes. They may work too, but I never tried.

[mockingbird]

Momaka, does flux residue retard tin whiskering?

[momaka]

Yes.
Part of the reason why tin whiskers form is solder oxidation and flux keeps solder from oxidizing too much.