Ultra-high-performance heat spreader based on a graphite architecture with three-dimensional thermal routing

Abstract

To meet the increasing demand for highly efficient heat dissipation in power electronics, a heat spreader that has significantly greater isotropic thermal conductivity than the commonly used copper (400 W/m·K) should be developed. Although graphite is a promising candidate because of its high basal-plane thermal conductivity, its application is restricted by its low c axis thermal conductivity. This issue can be resolved by transforming graphite into an isotropic thermal conductor by building a structure that can effectively route heat in all three dimensions. Herein, we develop a double-decker structure with differently oriented graphite layers to realize high heat dissipation from a local heat source. The critical issue of bonding the graphite layers is overcome by a high-temperature process using Cu as the binding layer. The graphite/Cu composite efficiently dissipates heat nearly isotropically and performs as well as an isotropic conductor with a thermal conductivity of 900 W/m·K. Anisotropic thermal conduction of graphite is overcome by 3D thermal routing Isotropic heat dissipation is realized by a double-decker structure of graphite blocks Performance comparable to isotropic materials with thermal conductivity of 900 W/m·K In this paper by Xu et al., the anisotropic heat conduction of graphite is overcome by assembling graphite blocks into a double-decker structure, which provides effectively isotropic heat dissipation comparable to isotropic materials with thermal conductivity as high as 900 W/m·K. This is more than twice the value of the typically used copper.