Thermal expansion behaviour and dimensional stability of Diamond/Cu composites with different diamond content

The Diamond/Cu composites with bimodal diamond particles reinforced were fabricated by vacuum pressure infiltration. The influence of diamond volume fractions on the microstructure, thermal expansion behaviour, residual Stress and dimensional stability of the composites were investigated by using scanning electron microscopy, X-ray diffraction, Raman spectroscopy and thermal cycling tests. The CTEs of 3.8–5.8 ppm/K at 50 °C were achieved for the Diamond/Cu composites, owing to the high diamond content (63–81.8 vol%) and the strong interfacial bonding strength. The CTEs of Diamond/Cu composites vary by less than 2 ppm/K in the range of 50–300 °C.Thermal cycling tests show that the residual strain of Diamond/Cu composites ranges from 1.6 × 10−4 to 1.0 × 10−4 as the diamond content increases from 63 vol% to 81.8 vol%. Increasing the diamond content introduces higher residual tensile stress, so the total residual strain drops slowly when the diamond content exceeds 72.5 vol%. The results show that an appropriate amount of diamond addition can obtain a coefficient of thermal expansion matching the semiconductor material and a high dimensional stability of Diamond/Cu composites.