Frequent readers will recognize Frostytech's long time coverage of non-metallic heatsink materials. Some materials, like diamond, offer unheard of heatspreading capabilities. Industry focus has been on carbon-based heatsink materials, whether that be graphite strands, carbon/graphite foam, carbon nano-fiber, or a metal-graphite matrix.

Here are a few previous news stores that cover a range of non-metallic heatsink technologies.

Fuzzy Carbon-Fiber Heat Exchangers From FERMILab: Carbon Fiber is a staple of F1 cars, aircraft, and low-weight high-strength applications. Carbon also has a nice natural property that in the right state, it has pretty good thermal conductivity characteristics. Aluminum sits at 247 W/mK, Copper 398 W/mK, Silver 428 W/mK, and diamond 2000 W/mK. Diamond is an expensive form of carbon for a heatsink, whereas graphite (25-470 W/mK) and Carbon Fiber (100-520 W/mK) are much more affordable, very light weight options. Researchers at ESLI conducted tests on a small carbon-fiber felt and tube heat exchanger for FERMILab, to cool silicon chips bonded to its fuzzy surface (above). Fluid is pumped via a Neslab chiller through the manifold to test the responsiveness of the amorphous carbon-fiber tube and felt design, called "Cooled Fintube Structures." Carbon Fiber has the benefits of a thermal expansion matching silicon, high strength to weight, nonpermeability, and high radial heat transfer according to the researchers.

Anisotropic nano Carbon Fiber heatsinks : There is a really good presentation on the potentials and limitations of Anisotropic nano Carbon Fiber heatsinks (thermal conductivity of 650 W/mK) right here at Thermocomposite.com The company has developed an "Oblique Angle Anisotropic Carbon Fiber Heatsink" that looks rather like a foam tile from an anechoic chamber. The geometry is neccessary because of the way carbon fibers conduct heat, in order to maximize the cooling surface area. "If using a uni-directional, anisotropic conductive fiber in a conventional heatsink fin design, you don’t gain the benefit of the area on the sides of the fins/pins because the heat will only transfer from the cool side ends of the fibers so its equal to using a non-finned block of material. The “patented” oblique angle on at least one end of the fiber creates a greater surface area for thermal dissipation or transfer to other fibers. The oblique angle works on both a Micro-(fiber) and a Macro (structural) level. Even hollow fibers need to be terminated on a oblique angle pin/fin to maximize surface area of the fiber array exposed to the cooler environment." Thermocomposite prototype nano conductive carbon fiber heatsink being tested.

Cooling using Diamond Evaporators, Carbon Foam: "Carbon foams have been demonstrated to be more efficient than typical heat sink materials • Power densities up to 100 W/cm2 have been demonstrated at temperatures less than 100°C" Evaporative Cooling Developed By National Security Agency (NSA) in Collaboration with ORNL. "Foams will be utilized to replace copper and diamond evaporators and condensers in thermosyphon Ø Typical diamond evaporators yield ~ 28W/cm2 maximum cooling power at 100°C max temperature"

Graphite Foam Heat Exchangers and Heatsinks: A good though old introductory article based on Oak Ridge National Laboratory research, that discusses the potential Graphite foam has with respect to heatsinks, and its limitations. "There are other possible uses for foam heat sinks, as well. They may prove useful in protecting electronic components on space satellites from heat damage. Another possible application would be in evaporative cooling, in which the high specific surface area (>4m2/g) combines with the high thermal conductivity to produce very efficient cooling as water evaporates from the foam surfaces."