Natural Graphite Sheet Heat Sinks With Embedded Heat Pipes

Abstract

Natural graphite sheet (NGS) is a candidate material for lightweight, high-performance heat sinks. We show that the low through-plane thermal conductivity can be mitigated by using heat pipes. In the measured configuration, the thermal resistance of an NGS heat sink with embedded heat pipes is comparable to that of a geometrically-identical aluminum one. The achieved weight reduction is 37 %. When electrical insulation of a heat sink is not required, soft and conforming NGS does not require thermal grease at the interface between the heat source and the heat sink. The low electrical conductivity of NGS does not lead to a decrease in common mode conducted emissions, but the potential to reduce the radiated emissions was quantified to be 12 to 97 % based on an analogy with antennas. In practical applications, replacing an existing heat sink with a geometrically identical NGS one is not recommended because it limits the achievable improvements in thermal performance, weight, and cost. Instead, we suggest using an optimization algorithm to determine the optimal heat sink geometry.