Effective thermal conductivity of a diamond coated heat spreader

摘要

Thin diamond coatings are often suggested to enhance thermal conductivity of some substrate. We measured the effective thermal conductivity of varying thicknesses of diamond on tape cast, polycrystalline silicon carbide. The effective thermal conductivity of 30 μm diamond on tape cast silicon carbide is 1.7 W/(cm K). The effective thermal conductivity can be increased to 2.2 W/(cm K) by increasing the diamond thickness to approximately 70 μm. With the measured effective thermal conductivity, the thicknesses of the diamond film and substrate, and knowledge of the thermal conductivity of the substrate material, the thermal conductivity of the diamond layer can be calculated from a simple formula. The thermal conductivity of the 30-μm and 69-μm diamond layers were found to be 3.9 W/(cm K) and 5.8 W/(cm K), respectively.