Annex B) Diamond, Nano-structure and Metal Foam Heatsinks

Metafoam Technologies For Waterblocks, Heatpipes and Acoustics: Metafoam is thermal solution manufacturer based in Canada, the company has produced a collection of products which revolve around its core metal foam technology. These include high surface area open-cell metal foam cold plates, heatpipes and acoustic absorbers. "Tests results show that with a 6 cm thick metal foam, 60% of noise at 300 Hz is dissipated and the absorption coefficient is at least 80% for frequencies higher than 500 Hz. For a 2,4 cm thick sample, the absorption coefficient is still higher than 80% at more than 1500 Hz. Furthermore, we demonstrated that transmission losses are more important with a 10 mm thick metal foam than with a 50 mm thick conventional polymer foam." With regard to waterblocks Metafoam offers an alternative to machined surfaces by inserting copper foam in the water block. According to the manufacturer, first prototypes already perform better than high-end commercially available CPU cold plates because the metallic foam's microstructure yields very high surface area which drastically increases contact surface with coolant. For Heatpipes, Metafoam enhances heat pipe capillary force with its unique metal foam wick. Initial prototypes tested by external laboratories already show a 100% increase in performance compared to conventional screen mesh wicks, according the company.

Foamed Metal Heatsinks and Heat Exchangers: While this may look like sponge, what these panels and prototype heatsinks are made of is foamed metal, either copper or aluminum. The benefit of foamed metal is incredibly large surface areas, the downside is restricted airflow. High pressure fans are a must. Still, with heatpipes or watercooling set ups this new avenue of heatsink production could prove quite lucrative. As FrostyTech reported previously, Carbon foam, Fuzzy Carbon-Fiber, and Anisotropic nano Carbon Fiber heatsinks are already being built in laboratories, so there are certainly benefits to this technology that mainstream commercial manufacturers have yet to fully realize. The samples were showcased at CEBIT 2006 by FPE-Fischer, however if your company is developing something similar, be sure to let us at FrostyTech know all about it.

Multiwall Nano Tube Thermal Interface Mats + AS3: This power point presentation discusses a new way of mounting heatsinks, by using a combination of high thermal conductivity thermal compound and something called a "multiwall nano tube thermal mat". The so-called "thermal mat" is used between the base of the heatsink and CPU to fill in large voids. The University of Maryland research indicates that the best results are had by coating the heatsink base and CPU integrated heat spreader with thermal compound separately. In the author's tests, thermal joint resistance was lowered from 78 W/CM2 to 3 W/CM2.It's an interesting read.

Diamond based thermal interface materials: HeaThru is a breakthrough diamond composite family, with keynote product DiaCu, a diamond/copper composite with extremely high thermal conductivity for the IC thermal management industry. HeaThru DiaCu is currently used in heat spreaders, heat pipe, and heat sink applications. It is offered in two levels of conductivity, DiaCu-1 and DiaCu-II, at approximately 2x and 3x the conductivity of copper, respectively. HeaThru DiaSil is our diamond-silicon composite, geared toward low electrical conducitivity, precision CTE-matching needs. Heathru DiaPaste -- Advanced Diamond Solutions, Inc. now carries a breakthrough complementary diamond-based thermal interface product line to maximize the effectiveness of its DiaCu and DiaSil composite lines. Heathru DiaPaste is a high thermal conductivity diamond-filled thermal paste for lowering thermal junction resistance. DiaPaste is a perfect complement to any project requiring a low-cost high thermal conductivity TIM (thermal interface material), where soldering or other fixed-bonding is not feasible.