T. Schubert, L. Weber, R. Tavangar, T. Weissgärber, B. Kieback

Novel heat sink materials reinforced with diamonds have been produced via powder matellurgy. As matrix, copper alloys with boron content between 0.5 and 2 wt-% have been chosen. Prepared composites have been investigated regarding microstructure and interesting properties such as thermal conductivity, thermal expansion and their evolution after 1, 4, 16, 64, 256, and 1024 thermal fatigue cycles between -50 and 130°C has been measured. Transmission electron microscopy as well as focused ion beam microscopy has been used to study the carbide formation at the matrix-diamond interfaces. The thermal conductivity achieves a maximum (>600 W/mK) at boron levels of about 0,5 wt-% (2.9 at-%) and decreases slightly at higher boron contents. This decrease of TC is compared to modelling of two extreme situations, i.e. all boron at the interface and all boron present in the matrix. After thermal cycling test up to 1024 cycles the copper composites with good interfacial bonding show some decrease in the thermal conductivity and a relatively stable CTE in the range of 7-8 ppm/K.

CuB/Diamond Composites

Download complete paper