The thermo-physical properties of high dense Mo/Cu composites fabricated by squeeze casting technology

Abstract

For applicability in the field of semiconductor, it is important that the thermal expansion coefficient of heat sink materials approximates to those of semiconductor chip and peripheral material. In addition, high thermal conductivity and densification also is required. Mo/Cu composites are desirable for thermal management applications because of its combination of low thermal expansion coefficient and high thermal conductivity. In this paper, Mo/Cu composites with volume fractions of 55% /spl sim/ 67% Mo content have been fabricated by the cost-effective squeeze-casting technology. The microstructures and thermo-physical properties of the Mo/Cu composites were investigated. The experimental results showed that: (1) the full densities of the Mo/Cu composites were achieved and the microstructures of the Mo/Cu composites were homogenous compound structures of adhesive phase Cu linking Mo grains. (2) The mean linear coefficients of thermal expansion (20 /spl deg/C /spl sim/ 100/spl deg/C) of Mo/Cu composites ranged from 7.9 to 9.3 /spl times/ 10/sup -6// /spl deg/C and decreased with an increase in volume fraction of Mo content. The experimental coefficients of thermal expansion agreed well with predicted values based on Kerner's model. (3) Their thermal conductivities were increased with the increasing of volume fraction of Cu content and as high as 220-270 W/(m/spl middot//spl deg/C). This was attributed to the fact that the full densities and high purity of Mo/Cu composites were achieved through the cost-effective squeeze-casting technology processes. As a result, the properties of the Mo/Cu composites are good enough to satisfy electronic packaging applications.