Diamond / Copper Composites

The electronic packaging technology in modern ICs and other electrical components has a specification-advanced demand for packaging materials. Advanced packaging materials demand lightweight, higher thermal conductivity (TC) and lower coefficient of thermal expansion (CTE). Diamond/Cu composites have a promising potential in future application due to their good combination of TC and tailorable CTE. But previous research of Diamond/Cu system is still not satisfied both in the theories and engineering aspects.Monocrystalline diamond powder was used in present work, Diamond/Cu composites were prepared by powder metallurgy under the different molding process (repressing and re-sintering technology, vacuum packing hot forging technology, vacuum packing hot extrusion technology). The microstructure of the diamond/Cu composites were observed by XRD, Metallurgical Microscopy and SEM methods. The coefficient of thermal expansion and density of composites were measured. The effect of different molding process technology on the density of samples was analyzed. The effects of volume fraction and powder size of diamond on the coefficient of thermal expansion were also discussed.By analying the densiy and the coefficient thernal expansion of the composites of 40μm 70vol.%diamond/Cu prepared by three different technologies, the results showed that the relative density could be gained to 82.82% and the coefficient thernal expansion 6.4-7.5×10"6/K at 50～100℃prepared by repressing and re-sintering technology (singtering temperature:890℃;singtering time:8h);the relative densiy 79.584～80.692% and the coefficient thernal expansion 11.315～11.647×10-6/K prepared by vacuum packing hot forging technology and the relative densiy 70.125%and the coefficient thernal expansion 7.864×10-6/K prepared by vacuum packing hot extrusion technology.The coefficient of thermal expansion of the composites were tested and analyzed. The results showed that the coefficient of thermal expansion increased with the temperature lighted, the diamond particle size increased and the volume fraction of diamond reducedThrough theoretical calculation, the coefficient of thermal expansion reduced with the increasing of the relative density of composites, the volume fraction of diamond and the decreasing of diamond particle size were found. Calculation value is smaller in comparison with measured. The experiment data were more closer ROM and Kerner model with lower diamond volume fraction and were higher than throretical data with higher diamong volume fraction.