Prepared By Powder Metallurgy To The Study Of The Si-al Electronic Packaging Materials

In this paper, the powder metallurgy liquid sintering technology was applied to make the silicon-aluminum composite, which is of good properties of lightweight low expansion and high thermal conductivity. The compsite with high Si contant was investigated. The effects of fabrication technology parameters on the compactibility and properties (density , thermal conductivity , coefficient of thermal expansion) of Si-Al composites,which including compacting pressures, sintering temperature ,> sintering time, cooling rate, heat -treatment and Si content ,were researched. At the same time, the wettabil, interface reaction and microstructure of Si-Al composites by different treatment were discussed by optical microscopy , X-ray, DTA and SEM methods. The conclusions were shown as below:1 . It's available to obtain the high properties Si-50wt%Al electronic packaging materials by powder metallurgy liquid sintering technology. The thermal conductivity can be gained as 131 W/m ?K, the coefficient of thermal expansion as 9.41 - 10.44 X 10'6/K and the density as 2.48g/cm3.2. Composites density and properties elevated with increasing compacting pressure, but ultra-high press would make too many microcracks in Si particles, and then lower thermal conductivity of composites.3. Proper high sintering temperature and proper long sintering time would contirbute to improve wettability, decrease interface amout and form continuous Al phase network, which should be benefit to thermal conductivity and coefficient of thermal expansion of composites. However, coefficient of thermal expansion is mainly up to Si content.4. Many eutectics and long columnar Si particles, which formed due to low cooling rate, degrade the composites properties. And the followed heat-treatment contributed to decrease the lattice distortion and residual stress and improve properties of composites.5. The main densification mechanism of Si-Al composites was rearrangmentand solution-precipitation stage. Due to the fracture of aluminum oxide film, Si/Al system exist a nowettability/wettability transfermation process at about 950 癈. The interfact reaction between Al and silicon dioxide would improve with the increasement of sintering temperature and time.