Fixing Aixismodule to Copperheatsink with solder?

[TimTom]

Hi guys,

look at this picture:

And tell me if its possible, to fix the aixis module with solder to the copper heathink.

Im actually don't know a better way, that may would works permanently.

Any suggestions?

Thank you!!!!:wave:

 

[ARG]

Well, soldering to aluminium is extremely difficult due to it's thermal conductivity, so it would be harder for copper (if it is even possible)

 

[TimTom]

I wondered how easy it was, to solder the solder to a copper ring. I think it happened so easy, because the soldering iron was as about 450 degrees.. I soldered with the same temperature the second part from the module and it worked very good.. but im worried about the temperature and I dont wanna damage the diode.. should I try it? :s

Im going to try it, #yolo :'D

 

[KRNAZNBOY]

Why not thermal adhesive? Arctic Alumina would be permanent and would conduct heat well?

Would be the obvious solution no?

 

[crazyspaz]

I second that...use some thermal epoxy. Trying to solder it will get you nowhere, and you risk damaging your diode with heat if you hold the iron on it too long

 

[Zeebit]

You could do it using a big ass soldering iron or torch used for joining metals but of course remove the diode first.
Like what the others said, its possible but not worth the hassle.
Thermal epoxy is the way to go

 

[shokkunlasers]

Its possible I've done it with copper pipes a few times but you a lot flux and a blowtorch or very powerful solder iron.
Just look on youtube for copper pipe soldering

Don't do this with the diode pressed in the module it may overheat!!!

 

[TimTom]

Already did, it works. Looks quite ugly and the "lens" of the diode is a bit dirty.. whateva.

 

[Marco Polo]

I imagine sweat-soldering it like copper pipe would work, prior to installing the diode.

According to this link the thermal conducivity of 60/40 solder alloy is 49.8 W/m*K. So, about 50 W/m*K. This is what I would use since I have a lot of it on hand. Wikipedia gives similar values for SnPb 63/37 and ~60 W/m*K for various lead-free solders. Link is here. All of these values are much lower than copper, aluminum, and even brass.

This page gives the conductivity of SnAg 96.5/3.5 as 78 W/m*K. It is one of the lower-melting ones, also.

However the Wikipedia list also gives the conductivity of silver-based thermal grease. If solder alloy is bad, then I don't know what to call thermal grease. Based on that list, the conductivity of grease is less than 1.0 W/m*K, making the solder's conductivity ~50 to ~60 times that of thermal grease. But then, soldering a module into a heatsink is an involved task, even more so if the intent is to retrofit an already-built laser.

Grease, OTOH, is easy to use and replace as needed, but far as I can tell that's the only thing it has going for it. That, and you can't very well sweat-solder a heatsink to your overclocked i7 unless you want burnt silicon for dinner. I wouldn't expect laser modules or their heatsinks to have that problem, as long as there's no diode installed in it.

It seems to me that as long as the soldering job is good and there are few/no air voids in the joint, solder would be vastly superior to grease, at least where raw numbers are considered. It looks good on paper. But then, maybe the process of soldering could deform the heatsink so that it (or the diode) no longer fits, or maybe cause some sort of oxide buildup that impedes heat transfer. Maybe the flux would cause some kind of problem.

In any case I wouldn't want to do it with a diode already installed, since you'd have to heat the heatsink and module to hundreds of degrees, at least 300°C and maybe more, to ensure that the solder flows well enough to thoroughly saturate the joint and eliminate all air voids. You'd probably want to polish away any oxide that forms on the heatsink's surface as well. At that point it might be easier (although probably more expensive) to have a member craft a one-piece heatsink if heat transfer is that big a deal.

I would think the best way would be a copper AixiZ module and a copper heatsink, using solder designed for plumbing or HVAC sweat soldering. The only thing I've heard about soldering to aluminum is that it requires special solder and flux, and is generally a PITA.

Interesting idea all around though, might be worth it if you're building something with that 3.5W 445 or similar high-power diode. But then again, if you can afford that, you can probably afford a custom heatsink too. Oh well, just my thoughts on it based on the numbers I looked up.