? for ATS computer techs:Reflowing laptop motherboards, heat gun or oven?

I enjoy fixing broken electronics.I come across my fair share of laptop motherboards with bad connections.

Many of the laptops have issues with the quality of the solder used in mass production.This creates issues most often with the gpus and the as a result nothing appears onscreen, even though they power up.This problem is aggravated through overheating and wear and tear over time.

There is a technique, known as reflow that attempts to use heat to melt the solder back, typically done by stripping the board and applying heat via a heat gun, or baking it in the oven.

For those who cook their electronics like this, which technique do you prefer: heat gun or baking in the oven?

a reply to: dffrntkndfnml

Surface mount, not pin thru, right? Reflow of old solder hardly works, it becomes brittle. Use of heat gun preferred, though. Remove the chips, then old solder with Solder Wick and then use new solder paste and oven this time to remount the chips. Seems like over kill, have you inspected the board visually, sometimes power and cable connects are where opens occur (if thats the problem).

This opinion was brought to you by an old school tech from Silicon Valley hey days… I'm sure a lot has changed since then.

a reply to: dffrntkndfnml

I presume you've isolated the fault by pressing down on the BGA to see if you can make contact and change the system behavior.

If you are reflowing anything on a populated board, the strategy should be to apply as little heat as possible. For BGA's you should first take the time to fabricate a insulating screen for nearby components, then hit it with hot air.

Know your process chemistry. ROHs compliant solder needs higher temps. You might consider thermocoupling the opposite side of the board to take some of the temperature guesswork out of the operation. There will be a temperature offset to empirically determine between the target chip junction and the opposite side of the board. Don't be disappointed if it only works 80% of the time.

safety first & enjoy.

a reply to: dffrntkndfnml

Heat gun is how I do it (hair dryer will work though it takes longer).

Remember though that, unless you could replace all of the low lead solder, this is a temporary fix and not a solution to the problem.

Sweet, thanks everyone.

I'm between contracts atm, so this gives me time to work on this hobby of mine.

A variety of older laptops have been waiting for me to practice.They're already toast, lol so I can experiment with different techniques.Pushing the sweet spot definitely changes system behavior, so that unit will be my first candidate.I have multi-meters, infrared thermometers, heat guns, and other tools to help.

There isn't any pressure to succeed, I just want to try everything before they go to the recycle depot in sky!

A part of me sometimes feels a little sad, there are many electronics that could be fixed, but it's more convenient to get another then spend the time or money working on the original.Laptops got me interested in this technique, though my friends have told me it can be used on video game systems as well.

Keep the tips coming, there appears to be a bit of an art to this, so I wanted to ask our community.

I'd say oven, but that's probably because when I tried a heat gun reflow I melted some plastic power connector and a capacitor fell off once. I didn't have that problem with an oven.

a reply to: InverseLookingGlass

I presume you've isolated the fault by pressing down on the BGA to see if you can make contact and change the system behavior. /quote]
Gentlyyy…

Good idea to also slowly open and close the unit while booting to see if it spits garbage on screen suddenly (an intermittent open), the worst kind. It does localize the problem to the connections. At that point get a new lap top, it ain't worth the effort.

The open could be anywhere, or a failed component, reflowing the whole board might just create more problems. How would you tell though if theres nothing on screen?

Get a very large powerful magnifying glass. Most dry joints can be seen! Dont think I'd want to apply heat to an old board, could cause more problems! Heat is about the only thing that destroys semi's, seem to remember reading something like every 5 degrees reduces a components life by 15 years!

a reply to: dffrntkndfnml

Don't reflow with a heat gun if you value the hardware at all. You'll have it up and running for a short period of time, but you'll have caused irreversible damage in the process. You need a BGA reflowing station to do this properly, any sort of oven / heat gun trick is temporary and always damaging.

originally posted by: VoidHawk
Get a very large powerful magnifying glass. Most dry joints can be seen! Dont think I'd want to apply heat to an old board, could cause more problems! Heat is about the only thing that destroys semi's, seem to remember reading something like every 5 degrees reduces a components life by 15 years!

I agree with this poster. 99% of electrical problems are visual.

a reply to: SpongeBeard

On the net, many posters shared better results using an oven as opposed to a gun. By better, longer lasting. Offline someone told me go with the gun first. Idk, this exercise for fun. This hardware has just been gathering dust for the longest time.

a reply to: proob4

I don't have a powerful magnifying glass, though I'll turn the light on my phone and zoom in digitally with the camera for a closer examination. That's a trick we use for examining prints in the field...

I wouldn't recommend either technique for repair, but at least with a heat gun you can direct the heat. Electrolytic capacitors can explode if overheated.

originally posted by: VictorVonDoom
I wouldn't recommend either technique for repair, but at least with a heat gun you can direct the heat. Electrolytic capacitors can explode if overheated.

Electrolytic caps will not explode just setting there. They have to either have dialectric leakage and be powered up with sufficient ripple from the supply to cook them to extinction. They will only explode with excessive ripple near their rated capacity.

And 99% of component failure is heat. But again Power must be on.

Reflow of multilayer circuit boards are difficult at best and can often result in additional problems.

Play with junk and get a feel for it. But you dont want a bunch of smd's falling off when overheated.

Njoy