Laserwave 1 watt OEM V-S

[dnar]

No, looking into this now as you have sparked my interest.

[badger1666]

Eric I found on the two I have they had machined the open ended slots of the oem-v after the base ,leaving ridges around the slots

[The_Doctor]

I used sheets of silicon rubber thermal material on a job once, between microwave video modules and chassis that was great, although I am not sure how this would go under laser modules.

I built a silent 1U rackmount ITX computer with no moving parts, about 180mm from front to back. To do it I needed to get heat passed to the 3mm thick Al backplane I'd cut by hand, and to the long vaned heatsink I'd put on that. I tried at least three things, none of which coupled anything like enough heat out of the CPU, so no matter how good the rest of it was it was looking worthless and stupid. Then I found this: RS Components (yes, again) 446-475. Apparently NASA use it too. It totally works. And it's about as cheap as I've seen, stuff like it is usually too expensive for me to contemplate. When I used it I just fit my lapped block to the CPU by weight, marked carefully the two M3 hole centres based on existing holes in the backplane. When lining up the holes later to clamp it, the yeild in the PCB and the thermal pad combined to give an ideal fit. Where a CPU temperature was caught passing 90°C in an earlier test, it stopped below 60°C, rarely passing 55°C. Thicker versions exist that will be better for undersides of soldered through-hole boards.

[The_Doctor]

Planters, do you know the melting point for that gallium based stuff? Also, an affordable source for small quantities? I've wanted to try something like that too, but so far decided that solid was less risky, using indium based alloys with bismuth or tin, temperatures of 76°C, 117°C and such, for staged assembly on a hot plate. Especially good where TEC's are involved. But a liquid metal lining the rim of a diode mount is something I want to try.

[planters]

I bought the low temp alloy I have from Indium Corp. It was not inexpensive, but I bought it over a year ago and there may be small quantities available now. The problem you might have is that the gallium based alloys that remain liquid at RT are pretty corrosive. CPUs have what looks like a thin plastic film covering the packaging and copper (the heat sink) is one of the more resistant metals to gallium. I wouldn't even think about this for use with any aluminum capped diode. I expect that with the very high clamping pressure that a typical diode mount applies to the diode flange that the metal deformation will probably ensure pretty good heat flow. My new concern is with these brass mounts. My new 9mm diode modules dump about 10W per diode into the base plate and when operating at 100% steady state power output the top of the mount gets VERY HOT. My guess (I'll measure it today) is around 50C. I use indium film thermal interface and a water cooled base plate. I'm going to have to re-fabricate these from aluminum or (gasp) copper.

[The_Doctor]

Hmm, diffusion into other metals might be a bitch too. There's a thing called HTS2000 used to braze aluminium, and I decided to steer clear of it (I posted about it at length in a 7-year-old thread somewhere here on PL). The stuff eats the substrate forming greater density and lower melting point! Disastrous. Like poring boiling water onto an ice block. Pores, fissures, collapse. If any liquid metal does that even the tiniest bit, it's going to go on doing it, with hell knows what long term unwatched consequences. Maybe I'll stick to my indium solders. They're not cheap either but at least they stay put.

EDIT:
About the brass mounts, my solution is this: Solder them on to the copper-clad TEC upside down. For one thing that gets me two neat tapped M3 holes for mounting stuff onto them with. The other is much less brass for heat to flow through.

[dnar]

EDIT:
About the brass mounts, my solution is this: Solder them on to the copper-clad TEC upside down. For one thing that gets me two neat tapped M3 holes for mounting stuff onto them with. The other is much less brass for heat to flow through.

If you can securely solder brass mounts to a TEC with enough heat (and it's going to take andy_cons uber-iron x 42) to get the mounts to temperature while also not killing the peltiers, then your a far better man than I....

Thermal epoxy adhesive maybe...

Hang on, I just had an epiphany, time to stay quiet for a bit until I work this through my neural networks (or the Shiraz wears off and I realise it's a stupid idea, or I forget totally which is usually the case).... [looks for notepad and pencil]

[dnar]

Er, looking in my rear vision mirror, this thread is seriously and unequivocally OFF TOPIC!

A hallmark of all good PL threads.

[planters]

No, it's not the interface I'm talking about. I lap everything including Dave's mount's and machine flat my base plates so that even dry there is that momentary suction when pulling them apart. I hard clamp my mounts onto an indium foil interface. The problem is the brass itself. The thermal conductivity of brass is low and likely the problem starts from the small cross sectional area where the diode rim contacts the brass. This bottle neck is likely why the manufacturer went from a 5.6mm to a 9mm flange and all the host projectors use at least aluminum for this mounting function.. Nevertheless, the top of the mount gets hot. With the screws and the lens bore and the diode clearance there is not really a lot of this poor conductor available to transfer the heat down to the plate. The interface(s) don't help, but if well executed, I don't think they are worth worrying about.

[dnar]

No, it's not the interface I'm talking about. I lap everything including Dave's mount's and machine flat my base plates so that even dry there is that momentary suction when pulling them apart. I hard clamp my mounts onto an indium foil interface. The problem is the brass itself. The thermal conductivity of brass is low and likely the problem starts from the small cross sectional area where the diode rim contacts the brass. This bottle neck is likely why the manufacturer went from a 5.6mm to a 9mm flange and all the host projectors use at least aluminum for this mounting function.. Nevertheless, the top of the mount gets hot. With the screws and the lens bore and the diode clearance there is not really a lot of this poor conductor available to transfer the heat down to the plate. The interface(s) don't help, but if well executed, I don't think they are worth worrying about.

Hmmmm. Thinking about this, I have to ask why these diode mounts are made from brass in the first place? Why not aluminum which is also easier to machine?