Captherm makes a heatsink with high explosives

CES 2014: C4 makes for better welds and is more fun than a torch

Captherm logoCaptherm makes rather unique PC heatsink through a novel method, in this case welding with high explosive C4. That however is only the beginning with many other bleeding edge but not quite as shrapnel wound inducing technologies in their flagship MP1120.

The first problem is that the base of the heatsink is made of three types of metal, copper, iron, and aluminum as you can see from the slice below. They look like they are welded together but as most of you know you can’t actually weld dissimilar metals like that. If you use a glue you create thermal barriers, same with solders. The only way to make it work well as a heatsink material is to really weld the three metals which you can’t do through conventional methods.

Captherm MP1120 and slice of base material

A lot of high explosives went in to this device

That is where the fun comes in, conventional methods don’t work so Captherm uses unconventional methods like C4. The technique is called explosion welding and it is accomplished in the manner you might expect. Take a 1m x 1m slab of copper, lay a similar sized chunk of iron on top, then an aluminum plate. Go out to an abandoned quarry and place it on a flat, dry, and sold surface. Apply C4 liberally on top like frosting a layer cake of death, step back, detonate, and giggle a lot. The result is a slightly blemished but otherwise welded solid single plate of copper, iron, and aluminum. And a lot of smoke and debris.

With this explosion welding you get a single piece of dissimilar metals welded seamlessly into a single chunk without thermal barriers. Take a small block of this and C&C machine into the shape seen below to make the thermal baseplate for your CPU cooler. You might have noticed that the MP1120 above is clear on top, that is a glass plate for viewing the action.

What action? The hollowed out part is not just machined out, it is also coated with a sintered material to increase the surface area of the copper plate for better boiling. Boiling what you may ask? Captherm won’t say but it is a specifically engineered low temperature boiling fluid that will start to boil if you hold it in your hand. That would mean an ~72F boiling point so it is quite likely under low pressure too.

Since the latent heat of vaporization of almost all liquids is far higher than its thermal capacity as a liquid, the MP1120 can move a tremendous amount of energy quickly, it is basically a big heat pipe. The whole device is designed as a thermal pump so there is no energy needed to move the liquid/gas around, just a little power for the fan that is not shown in the picture above and the multi-color LEDs. The rest is passive, powered by the heat energy being dissipated.

The vapor goes up one pipe to the radiator then down the other side back to the pool. As long as you keep the energy input to less than the rated 275W you should never dry it out and all will be fine. That said 275W is a massive number for a pretty small passive cooler.

One thing about the MP1120 is that it isn’t cheap, it is closer to a work of art that works well. In short you will pay more for this than a normal heat sink but it is also quiet, efficient, and very high-capacity. Plus it was made with C4, how many people at the lan party can say that about their piddly little heatsink? The Captherm MP1120 is an impressive device, more so if you understand the tech that went in to it.S|A

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Charlie Demerjian

Roving engine of chaos and snide remarks at SemiAccurate
Charlie Demerjian is the founder of Stone Arch Networking Services and is a technology news site; addressing hardware design, software selection, customization, securing and maintenance, with over one million views per month. He is a technologist and analyst specializing in semiconductors, system and network architecture. As head writer of, he regularly advises writers, analysts, and industry executives on technical matters and long lead industry trends. Charlie is also available through Guidepoint and Mosaic. FullyAccurate