Liquid Heatsink Material

[LaserCo]

Here are a couple of aluminum filled epoxy products that I have used that may also work, but their cost would be prohibitive, especially for a one-time project.
Although these contain aluminum, and are excellant products, I don't believe their thermal conductivity would be anywhere near a solid heatsink. One good thing is they do get very hard, and are machinable.

1) Devcon
2) Loctite

IMO, with the all the machinists on LPF, and the reasonable rates they charge, a proper fitting solid heatsink is the best, and safest way to go.

On one of my first pointers I had taken a copper end cap for 5/8ths? 3/4? 1? inch tubing and sat outside with it and my torch and filled the cup with molten aluminum. I purchased 'special' rods I bought at Northern Hydraulics Northern/Tool for this task.
Hobart Low Temperature Aluminum Brazing Rods — 8-Ct. Pkg., 1/8in. Dia., Model# 770206 | Welding Sticks Wire| Northern Tool + Equipment

When it came to drilling that 12mm hole for an axiz type mount.. it was like I took out 80% of what I filled it with.. quite expensive.. and off center..(my fault, have x/y clamp for drillpress now)..

In the end I still ended up with a 445nm with a nice looking (dont look too closely) copper end.

EDIT: This method may really not be "quite expensive" as I said, with all considering.

 

[scifiguy]

After talking with a couple thermal engineers, I found this topic is actually a current leading edge effort, and there isn't any solution that's far ahead of the pack. Thermal compounds are typically in the 1 to 4W/m-k range. Here's an example of one of the more conductive materials:

BondPutty 4000, Thermal Gap Filling Putties « Universal Science Universal Science

However, one slightly better solution for filling large gaps is to use a mixture of compound with heat conductive micro beads. I haven't searched for those yet, but picture the smallest possible ball bearings. Metal fiber in the mixture is also a possibility, and has the advantage of being continuous down each strand, which allows better end to end conductivity.

 

[rusirius]

I'm new here, so let me preface this by saying that I honestly don't know just exactly how much heat would need to be sinked, etc...

With that said, when I read the OP the first thought that came to mind was one of the thick mesh-reinforced pads/paste. I know they used to use them in some of the old CPU sinks where there were larger gaps, etc. As I recall I think they are basically a mesh surrounded by a thermal pad on either side. The pad melts when heated filling in all the microscopic crevices in the metal on either side while the mesh works to conduct the heat through the two sides.

I don't recall how thick you could get them, but it might be at least worth looking into and at least finding out what their thermal conductivity is.

 

[VisibleGreen]

Hey guys I saw some 2 part thermal adhesive at radioshack today. Was 20 bucks and it was 99.9 percent silver. Would that be good to use?

 

[rusirius]

Hey guys I saw some 2 part thermal adhesive at radioshack today. Was 20 bucks and it was 99.9 percent silver. Would that be good to use?

I'm thinking you read the packaging wrong. Maybe it said it contained 99.9% pure silver... As in the silver (in whatever amount) it contained was pure. If it was truly 99.9% silver then only .1% would be left for other parts of the epoxy. Especially considering it's a two part I find that pretty hard to believe!

 

[USAbro]

^ditto I was gonna say that too. I can't imagine expoxy with only 1 percent left for the resin or hardener stuff.

 

[VisibleGreen]

I'm thinking you read the packaging wrong. Maybe it said it contained 99.9% pure silver... As in the silver (in whatever amount) it contained was pure. If it was truly 99.9% silver then only .1% would be left for other parts of the epoxy. Especially considering it's a two part I find that pretty hard to believe!

^ditto I was gonna say that too. I can't imagine expoxy with only 1 percent left for the resin or hardener stuff.

Yeah that makes total sense. Me brain not on today lol