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laser that can melt solder
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laser that can melt solder

by azakhary on Sun Sep 18, 2016 9:53 am

Hi, I am making a DIY 2 axis CNC that will "ink-draw" inverse of PCB, in order to later, etch the copper from not-drawn areas. I am also planning to have a changing "heads" for it. so that instead of ink pen I can have a DC motor for example, and drill the pcb. Now my latest thought was. what if I can attach a laser to it, so that it can auto-solder things, it will be pretty precise, and without soldering iron.
Unfortunately I have no experience with lasers, so my question is - is this possible to have a not very big laser with small power consumption that I can control with arduino, that ALSO can generate temperatures around 400C so it will melt a solder in one hit? If so, what the specifications should be and where to look for that kind of thing? will it be too big to put on my small CNC? Any advice much appreciated. Thanks.

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Re: laser that can melt solder

by adafruit_support_bill on Sun Sep 18, 2016 11:02 am

Mechanical issues aside, one concern would be that solder is reflective When using a laser cutter (which is essentially a 2D CNC with a laser head) to etch or cut most metals, it is necessary to first coat the metal with something that will absorb the light energy rather than just reflect it.

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Re: laser that can melt solder

by azakhary on Sun Sep 18, 2016 3:04 pm

I see your point. I wonder how this guys do it: https://www.youtube.com/watch?v=KnyB9btlhS8
Seems like some advanced stuff.

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Re: laser that can melt solder

by adafruit_support_bill on Sun Sep 18, 2016 4:56 pm

That is pretty slick! Most metals have different levels of reflectivity at different parts of the light spectrum. I suppose that you could try to tune the laser wavelength to those less reflective parts of the spectrum.

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Re: laser that can melt solder

by SDMI on Thu Dec 15, 2016 2:01 am

check out "selective solder" process machines.

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Re: laser that can melt solder

by marcwolf on Fri Oct 27, 2017 12:03 am

Well - Several things one can learn from the observations.

1. As the beam is invisible one can guess that we are talking CO2 laser. It will also need to be higher powered i.e. 40W or more with a very tight beam to get the precision heating and very small beam spot. So this is outside of your standard laser diode (blue or violet) system.

2. Most of the items they are working with are not highly reflective i.e. solder paste and solder wire. So combined with the power raised in point 1 - it should melt. It's only when it get liquid and reflective that you will have an issue however I believe that the beam is turned off long before that. The beam's energy is enough to start the solder melting, and then the conduction/dissipation of the heat does the rest.

3. An important feature that they use is that they have a monitoring system (think of the non-contact thermometers) that can measure the temperature of the beam point. This so that it allows the solder to get to melting point but not enough to vaporize.

Hope these help?

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