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 materials. In addition, high thermal conductivity also is required. The authors have studied a composite of molybdenum (Mo) and copper (Cu) prepared by two kinds of method, the mixing method (M/CM) and the cladding method (L/CM). The mechanical and thermal properties of these Cu-Mo composites can be controlled by varying the composition ratio.
In this paper, mechanical properties of the Cu-Mo composites were investigated. The thermal expansion coefficient α of M/CM increased with increase in copper content. The mean measured values of α in the temperature of about 30°C nearly corresponded with those calculated from Turner's equation and Kerner's equation. The observed anisotropy in α values was maximum for 50 mass% Cu content. The measured values of tensile strength, Young's modulus, Poisson's ratio and Vickers hardness showed a behavior similar the linear law of a mixture rule, but their values were a little smaller than the values calculated by the rule. The elongation and Erichsen value were discontinuous with the rule.
The α of L/CM was increased with an increase in Cu content. With the rise in temperature, Mo of the middle layer strongly controlled the thermal expansion. The mean measured values of α in the temperature of about 30°C were smaller than the values calculated by the mixture rule of material dynamics. Comparing L/CM with M/CM, the α values of L/CM were smaller than those of M/CM over the entire range of Cu content.
