Microstructures and properties of Al-50%SiC composites for electronic packaging applications

Al-50%SiC (volume fraction) composites containing different sizes of SiC particles (average sizes of 23, 38 and 75 mu m) were prepared by powder metallurgy. The influences of SiC particle sizes and annealing on the properties of the composites were investigated. The results show that SiC particles are distributed uniformly in the Al matrix. The coarse SiC particles result in higher coefficient of thermal expansion (CTE) and higher thermal conductivity (TC), while fine SiC particles decrease CTE and improve flexural strength of the composites. The morphology and size of SiC particles in the composite are not influenced by the annealing treatment at 400 degrees C for 6 h. However, the CTE and the flexural strength of annealed composites are decreased slightly, and the TC is improved. The TC, CTE and flexural strength of the Al/SiC composite with average SiC particle size of 75 mu m are 156 W/(m center dot K), 11.6x10(-6)K(-1) and 229 MPa, respectively.