Soldering with a laser

[Stiganator]

I was wondering, can you solder with a laser?

I was thinking it would be a cool project to make a maglight laser throw a focusing lens in front and mount in to a micron stepper motor then you could do some fine soldering.

Think it would work?

 

[PottedMeat]

I don't think it would be worth the effort. It would be cool lookin' though. You'd probably spend most of the money on an IR laser or whatever wavelength solder absorbs best. Then you would have to build a X-Y stage and program a PC-Iron controller. Plus it would have to read your circuit board files. There are probably many more problems too.

Aren't most boards put together with solder paste + reflow oven or by tacking components with glue and running them over a river of molten solder?

Do they still do the really fine point to point soldering with ultrasonic bonding?

 

[dkozloski]

Do a search on "solder toaster oven" and you'll forget the whole thing.

 

[CycloWizard]

It could be done if you can find a laser that is sufficiently powerful and is mostly absorbed by the solder. It would be pretty cool, especially if you interfaced it with your PCB design software so it could do it automatically after you laid out the board.

 

[ScottMac]

Laser wouldn't work. Lasers don't heat stuff, they vaporize stuff... ans that's not what you're trying to accomplish with solder.

 

[firewolfsm]

If a laser was powerful enough to melt the solder in an acceptable about of time, enough would reflect for it to cause damage elsewhere.

 

[dkozloski]

Laser soldering stuff is currently available but not widely used for production work because it's slow.

 

[Aluvus]

Originally posted by: ScottMac
Laser wouldn't work. Lasers don't heat stuff, they vaporize stuff... ans that's not what you're trying to accomplish with solder.

 

[CycloWizard]

Originally posted by: ScottMac
Laser wouldn't work. Lasers don't heat stuff, they vaporize stuff... ans that's not what you're trying to accomplish with solder.

How does stuff "vaporize?" By absorbing energy, usually thermally. Stuff usually vaporizes rather than appearing to be heated because the local heating rate is very high.

 

[Rubycon]

A laser is an ablative source of heat something you definitely do *not* want to solder with.

 

[ScottMac]

Originally posted by: CycloWizard

Originally posted by: ScottMac
Laser wouldn't work. Lasers don't heat stuff, they vaporize stuff... ans that's not what you're trying to accomplish with solder.

How does stuff "vaporize?" By absorbing energy, usually thermally. Stuff usually vaporizes rather than appearing to be heated because the local heating rate is very high.

If you see a laser doing something like wood carving, you'll see that there is no ash, no dust, no debris ... obviously, it's not just disappearing, all that stuff is going somewhere, but it
s not like it's heating it to the point where it smokes & flames. The wood is just "gone."

Industrial lasers for hole punching are similar ... there's no slag, possibly some sparks, depending on the metal, but no significant solid waste as a result of the lased hole or cut.

So, yes, I"m sure it gets really really hot ... in the area exactly where the laser is hitting ... that is NOT the kind of heating you want to accomplish a good solder joint.

Surface mount chips are placed on the circuit board, then the whole board is put into an oven to melt the solder. For some components, they still use a solder wave (pass the board over a molten puddle of solder).

If lasing was a better, faster, or more energy efficient way to solder, don't you think they would have adopted it for PC board production?

Watch an industrial laser at work sometime, it's pretty amazing.

 

[CycloWizard]

Originally posted by: ScottMac
If you see a laser doing something like wood carving, you'll see that there is no ash, no dust, no debris ... obviously, it's not just disappearing, all that stuff is going somewhere, but it
s not like it's heating it to the point where it smokes & flames. The wood is just "gone."

Industrial lasers for hole punching are similar ... there's no slag, possibly some sparks, depending on the metal, but no significant solid waste as a result of the lased hole or cut.

So, yes, I"m sure it gets really really hot ... in the area exactly where the laser is hitting ... that is NOT the kind of heating you want to accomplish a good solder joint.

Like I said before and you apparently didn't get, it depends on the power of the laser. If I aim a laser pointer at a piece of wood, it's not going to vaporize anything, nor heat it significantly. If I have a laser designed to cut metal, it's obviously much more powerful. Something in the middle could actually work.

Surface mount chips are placed on the circuit board, then the whole board is put into an oven to melt the solder. For some components, they still use a solder wave (pass the board over a molten puddle of solder).

If lasing was a better, faster, or more energy efficient way to solder, don't you think they would have adopted it for PC board production?

Watch an industrial laser at work sometime, it's pretty amazing.

I've been in the facility with massive lasers that are used to test fighter jet windshields. I've also seen lasers so small that they can be used to manipulate individual cells and molecules (e.g. optical tweezers). I've also hand-soldered surface mounts. And not everything is about being better, faster, or more efficient. Some people like doing things because they're fun/interesting.

 

[ScottMac]

Originally posted by: CycloWizard

Originally posted by: ScottMac
If you see a laser doing something like wood carving, you'll see that there is no ash, no dust, no debris ... obviously, it's not just disappearing, all that stuff is going somewhere, but it
s not like it's heating it to the point where it smokes & flames. The wood is just "gone."

Industrial lasers for hole punching are similar ... there's no slag, possibly some sparks, depending on the metal, but no significant solid waste as a result of the lased hole or cut.

So, yes, I"m sure it gets really really hot ... in the area exactly where the laser is hitting ... that is NOT the kind of heating you want to accomplish a good solder joint.

Like I said before and you apparently didn't get, it depends on the power of the laser. If I aim a laser pointer at a piece of wood, it's not going to vaporize anything, nor heat it significantly. If I have a laser designed to cut metal, it's obviously much more powerful. Something in the middle could actually work.

Surface mount chips are placed on the circuit board, then the whole board is put into an oven to melt the solder. For some components, they still use a solder wave (pass the board over a molten puddle of solder).

If lasing was a better, faster, or more energy efficient way to solder, don't you think they would have adopted it for PC board production?

Watch an industrial laser at work sometime, it's pretty amazing.

I've been in the facility with massive lasers that are used to test fighter jet windshields. I've also seen lasers so small that they can be used to manipulate individual cells and molecules (e.g. optical tweezers). I've also hand-soldered surface mounts. And not everything is about being better, faster, or more efficient. Some people like doing things because they're fun/interesting.

OK, so you're saying that lasers WOULD work for soldering, as described in the OP?

Read th OP, he's asking to use "a maglight laser throw a focusing lens in front and mount in to a micron stepper motor"

Do you think it'll work?

I vote "no. it won't" for a variety of reasons.

And, gee whiz, no, I NEVER do anything for fun or because it's interesting. It's a totally foreign concept.

Edit: as usual, Google can be our friend. Here's the top three non-sponsored links from a search "Laser soldering":

#1

#2

#3

So, as dkozlosky pointed out, it's in use.

Go figure.

 

[CycloWizard]

Originally posted by: ScottMac
OK, so you're saying that lasers WOULD work for soldering, as described in the OP?

No, I never said that it would work as described in the OP. I simply said that lasers could, in principle, be used for soldering - the FIRST question in the OP. I see that you have changed your mind and now agree with me. Wise choice.

 

[Throckmorton]

The laser will reflect off the solder and cause retinal burns.

 

[gsellis]

Originally posted by: Throckmorton
The laser will reflect off the solder and cause retinal burns.

At welding temps maybe, but you need to wear eye protection anyway with a regular welder because of the brightness. You are also assuming that the laser is in the visible light spectrum. A UV or Infrared laser would probably not. Also, the 'business end' could be a shrouded tip.

IOW, you could design it so it did not.

 

[CycloWizard]

Originally posted by: gsellis
At welding temps maybe, but you need to wear eye protection anyway with a regular welder because of the brightness. You are also assuming that the laser is in the visible light spectrum. A UV or Infrared laser would probably not. Also, the 'business end' could be a shrouded tip.

IOW, you could design it so it did not.

Your retina can get toasted by non-visible wavelengths too. But this isn't really important if the whole thing is automated. Just stick it in a box and you won't see anything. You could also put additives in the solder that would absorb virtually all of the energy at a certain wavelength.

 

[BladeVenom]

I don't know where some people get the idea that you can't solder with lasers. One place I worked had a laser welder.

 

[QuixoticOne]

It could certainly be done, however cost / practicality reasons usually discourage it.

Common solid/melted metal state solders are usually reflective / shiny at wavelengths that most cheap solid state lasers readily produce, so it takes more energy than is desirable to irradiate it and vaporize it if it is a shiny metallic wire solder or an already soldered joint.

If it is solder paste then it probably isn't that reflective, but it probably isn't that thermally conductive either, so you'll have to strongly irradiate the whole lot of it at once to get a good uniform melt.

If flux is involved then the flux outgasses / evaporates making smoke which absorbs / scatters the laser beam, so you'd have to have some pretty significant airflow to blow /suck the effluent vapors away before they interfere with the beam and coat the lens with a dirty opaque film which would be disasterous. These and other similar issues effect laser based welding, so you'd have to overcome those kinds of optics and material related issues.

CO2 lasers are relatively bulky and somewhat expensive though at that wavelength you might have less problems with vapor scattering and so on. I'm not sure about solder/paste reflectance; it could be better or worse or a similar mixed bag of problems / potential as with visible and near-IR wavelengths. Steering their beams is a bit more expensive than with near-IR or visible wavelengths also.

I believe there are some quality control problems with direct illumination heated IR reflow ovens because of the non-uniform heating rate of various PCB materials under the IR and depending on angle of IR incidence and shadowing effects and so on. You'd face at least some of those issues with an optical heating system, though it's certainly possible to achieve a measure of success with either if you use them in appropriately carefully selected ways / cases.

UV lasers are just too expensive and uncommon to use where there are cheaper and easier acceptable alternatives for now.

You'd have to have a pretty good list of advantages over direct iron heating or hot air jet heating or flame jet heating or oven heating to want to add powerful lasers to the mix.

On an industrial scale the cost difference of a few hundred or few thousand dollars may be somewhat irrelevant to the overall cost of a high end automated soldering process line or rework / custom assembly based system, though even then, the questions of cost / reliability / maintainability / quality control / throughput / safety wouldn't be irrelevant.

For personal use, making a hot air wand would probably be much more useful, cheaper, more simply constructed safely, et. al.

 

[johnywhy]

Laser soldering can indeed be done, and is done professionally.

 

[pcgeek11]

I know this is a necro thread. Lasers have been used for soldering for decades in production environments. The first I remember and was associated with was in 2003 for terminals for fuel injector manufacture. And they still do.