Effects of Particle Size on Microstructures and Properties of Si/Al Composites

Si/Al composites with different Si particle sizes were fabricated using spark plasma sintering process for electronic packaging. The density, thermal conductivity, coefficient of thermal expansion and flexural strength of the composites were investigated. Effect of Si particle size on structure and properties of the Si/Al composites were studied. The results showed that the Si/Al composites synthesized by spark plasma sintering were composed of Si and Al. Al was uniformly distributed among the Si phase, leading to a high thermal conductivity (>120 W/m.k). The relative density of the Si/Al composites decreased with increasing Si particle size. Small Si particle size produced small grains, leading to a low coefficient of thermal expansion and a high strength. There is an optimal matching among the thermal conductivity, coefficient of thermal expansion and flexural strength when the Si particle size was 44 um.