Microstructure characterization and thermal properties of hypereutectic Si–Al alloy for electronic packaging applications

The rapid solidified process and hot press method were performed to produce three hypereutectic 55%Si–Al, 70%Si–Al and 90%Si–Al alloys for heat dissipation materials. The results show that the atomization is an effective rapid solidified method to produce the Si–Al alloy and the size of atomized Si–Al alloy powder is less than 50 μm. The rapid solidified Si–Al alloy powder were hot pressed at 550 °C with the pressure of 700 MPa to obtain the relative densities of 99.4%, 99.2% and 94.4% for 55%Si–Al, 70%Si–Al and 90%Si–Al alloys, respectively. The typical physical properties, such as the thermal conductivity, coefficient of thermal expansion (CTE) and electrical conductivity of rapid solidified Si–Al alloys are acceptable as a heat dissipation material for many semiconductor devices. The 55%Si–Al alloy changes greatly (CTE) with the increase of temperature but obtains a good thermal conductivity. The CTE of 90%Si–Al alloy matches with the silicon very well but its thermal conductivity value is less than 100 W/(m·K). Therefore, the 70%Si–Al alloy possesses the best comprehensive properties of CTE and thermal conductivity for using as the heat sink materials.