Any of you who have ever even thought about overclocking are probably familiar with thermal paste and its function. Lots of OEM or low end cooling setups use either a thermal interface pad (TIM) or that white goop you get at radio shack. The fact is that neither of those does a great job of transferring heat from the processor to the heatsink. While they work ok, they don’t exactly assist Moore’s law in fulfilling itself by limiting clock speeds with heat. Yeah, CPUs are still getting faster, but one needs only to look at overclocking results with stock cooling versus those achieved with a good heatsink and good thermal paste to realize that better cooling = faster computers. Heck, if we’d stuck with the tiny old anodized fanless heatsinks on 486es, we might not be past 1GHz yet.
Current high end pastes range widely in composition, but in terms of performance they all fall within a very small degree range. Arctic Silver has been a longtime favorite among many, simply because they were the first company to release a competitive paste – one which was actually well suited to the task of transferring heat. Nanotherm is another big name these days, and lots of people are talking about PCM+, their upcoming metal-free product. But as I said, all of these products still get very similar results. A degree or two at most is all you can hope for in moving from one brand to another. So you might resign yourself to defeat saying, “Pastes have achieved perfection, so the bottleneck must now be the heatsink and the die of the CPU itself.” And that would seem to me a very reasonable thing to say…the fact that several companies are putting lots of resources into the development of more efficient thermal transfer and seeing diminishing returns is fairly strong evidence to support such a statement. But according to materials engineer Dr. Deborah Chung, current thermal pastes are rubbish, hooey, and applesauce, and she has something much better.
The paste she has created is based on dispersed carbon black (a particulate form of industrial carbon used to reinforce rubber) mixed in a soup of ethyl cellulose and polyethylene glycol. In tests comparing it to solder (a method of thermal transfer not typically used with electronic components because of the temperature required to bond it to both surfaces), the carbon paste surpassed the pure metal bond in thermal conductivity by 33%. It was also superior to diamond and carbon nanotube based pastes currently undergoing development. Even if the carbon paste were to merely match the diamond and nanotube pastes, it would be a significant improvement because of the cost differences.
Why does it work so well? Spreadability. The problem with current commercial pastes is that they have focused too long on the thermal conductivity of the material, and not on the fundamental principle of a thermal paste, which is gap filling.