Fabrication and characterization of diamond/copper composites for thermal management substrate applications

Diamond/copper composites have been made by the shock-wave consolidation method. The microstructures of these composites show uniform diamond particle distribution in the copper matrix. The composites exhibit positive residual strains after a thermal cycle which can be explained in terms of the large residual stresses in the shock-wave-consolidated samples and the weak interfacial bonding between diamond and copper. This thermal hysteresis behavior can be avoided by an appropriate heat treatment or by keeping the sample temperature below about 250 degrees C in the case of thermal cycling. Coefficients of linear thermal expansion (CTEs) of the composites are seen to decrease with increasing diamond content and generally fit the rule of mixtures (ROM) model.