Microstructure And Properties Investigation Of SiCp/Cu Composites

SiC particles reinforced copper matrix composites (Vf=55%), with the average sizes of 10μm, 20μm and 63μm, were fabricated by squeeze-casting technique for electronic packaging applications. The microstructures of SiCp/Cu composite were studied by using optical microscope, scanning electron microscope and transmission electron microscope. The physical and mechanical properties of SiCp/Cu composite were analyzed by means of analytical balance, thermal dilatometer, thermal conductivity tester, Brinell hardness and three-point bending tests, also with their influencing factors discussed. The SiCp/Cu composite with high densifications can be produced by squeeze-casting technique, and the densification of SiCp/Cu composite with particle size of 63μm reaches 97.8%, which is higher than the same materials reported in-country. The microstructure of SiCp/Cu composite are dense and uniform. TEM observations indicate high-density dislocations are found in the matrices of composites and the stacking faults in the SiC particles. The SiC-Cu interfaces exists interface reactions. And the analysis shows SiC particles decompose into carbon and silicon under high temperature, and the latter dissolves into the matrix copper to form a new CuSi solid solution, the carbon precipitates into copper and forms conglomerations with particle shapes. In the paper, the average CTEs of SiCp/Cu composite with particle size of 10μm gets 8.54×10-6/℃, which can meet the usage properties of electronic packaging materials. The CTEs of SiCp/Cu composite decrease with the SiC particle size, and after annealing the CTEs of SiCp/Cu composite are lower than that as cast. The thermal conductivities of SiCp/Cu composite increase with the particles size, which is related with SiCp/Cu interface thermal resistance. The investigations show that the decrease of particles size bring relatively larger interfaces which improve the effects of interface thermal resistance. Annealing treatment has little effect on thermal conductivity of composites. The mechanical properties of composites are superior. With the decreasing of the SiC particles size, the hardness, three-point bending strength and elastic modulus increase step by step. After annealing, the three-point bending strength of composites decreases slightly compared with that as cast, but the change of elastic modulus is not distinct. SEM observations show the particles are broken and flaked, and some dipples and ripping ridges are existed in the matrices. The fracture mode in SiCp/Cu composite are mainly brittle fracture.