Effective thermal conductivity of a diamond coated heat spreader

Thin diamond coatings are often suggested to enhance thermal conductivity o f 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 mu m diamond on tape cast silicon carb ide 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 mu m. With the measured effective thermal conductivity, the thicknesses of the d iamond film and substrate, and knowledge of the thermal conductivity of the substrate material, the thermal conductivity of the diamond layer can be c alculated from a simple formula. The thermal conductivity of the 30-mu m an d 69-mu m diamond layers were found to be 3.9 W/(cm K) and 5.8 W/(cm K), re spectively. (C) 2000 Elsevier Science S.A. All rights reserved.