Investigation On Al/SiCp Electronic Packaging Materials Fabricated By Gas Pressure Infiltrating Processes

Silicon carbide reinforced aluminum composites have great potential applications in electronic packaging because of its high thermal conductivity (TC), high strength, low coefficient of thermal expansion (CTE) and low density. Relatively low-cost facilities can be developed using a gas pressure to achieve infiltration. But till now we haven't understood some factors that affect infiltration process and need to investigate microstructure of solidification more.The threshold pressure P₀ is calculated by means of Capillary law of thermodynamics. The experimental results indicate that the compactness of fine particles for the SiC particles with bimodal distribution and particle diameter for the SiC particles with single distribution have a strong impact on the P₀. In addition, the Po is affected by the temperature of companess. When the temperature increases from 700℃ to 800℃, the threshold pressure P₀ for infiltration markedly decreases.Primary α—Al dendrite is hardly observed under the optical microscope by the presence of high volume fraction reignforce. Metal matrix mainly consists of Al-Si eutectic phases at the same time.The size and modality of eutectic Si phases are determined by size of SiC particles for single size paticle.The silicon shape changes from gross and long strip shapes to fine and dispersive punctate form as the particle size decreasing. It is abserved that eutectic Si phases are found to be nucleated by the surface of SiC particles.The effect of SiC particles with bimodal distribution on eutectic Si phases is similar with that of single fine particles. However, eutectic Si phases are finer appreciably among SiC particles with bimodal distribution.The effects of oxidation behavior of SiC particles at elevated temperatures on threshold pressure, interface reaction layer and matrix alloy solidification microstructure have been investigated in this paper. Infiltration of compacts of oxidized particulates is carried out. The results indicate that the thickness of interface reaction layer is about 200³00nm and the oxidized layer increases the threshold pressure by around 15 pct. As the same as not oxidized SiC particles,the reaction layer can also become the substrate for heterogeneous nucleation.