Microstructure and thermal properties of diamond/copper composites with Mo2C in-situ nano-coating

Abstract

Diamond/copper composite is considered to be one of the most promising electronic packaging materials, however, the inherently poor interfacial bonding between Cu and diamond make it difficult to obtain high thermal conductivity. In this paper diamond powder with an average particle size of 10 μm was modified with molybdenum carbide nano-coatings by magnetron sputtering and annealing process. Plasma Activated Sintering was then used to fabricate copper/diamond composites with different thickness of Mo2C interlayer. Field-emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterize the interlayer microstructure and phase composition of the diamond/copper composites. Differential thermal analysis, laser flash method and thermal-mechanical analysis were used to clarify the thermal properties of composites. The results indicated that diamond particles were distributed homogenously, discretely and randomly in the Cu matrix with improved interface wettability between diamond and copper by adding of Mo2C nano-coatings. The relative density and thermal conductivity increased with the thickening of Mo2C coatings, while the coefficient of thermal expansion decreased with the thickening of Mo2C coatings. The relative density, thermal conductivity, and coefficient of thermal expansion were 99.1%, 351 W·m−1·K−1, 9.27 × 10−6 K−1 with the Mo2C content of ~3.25 wt%.