Fabrication And Properties Of Al₂W₃O₁₂/SiC_p/Al Composite Used For Electronic Packaging

With the rapid development of science and technology, traditional materials are difficult to meet the needs of industrial applications. For electronic packaging materials, properties, such as excellent thermal performances, high thermal conductivity and low thermal expansion, are important for the applications. At present,Si Cp/Al composite material is a new type of electronic packaging material. Compared with foreign countries, Si Cp/Al composite is still in the research stage in China,because of its relatively high cost and poor thermal performances. The main purpose of this paper is the successful controlling of thermal performances by introducing negative thermal expansion Al2W3O12 particles to form Al2W3O12/ Si Cp /Al composite material. The main research works are as the follows:1. Negative thermal expansion Al2W3O12 particles with high purity and irregular polyhedron morphology were prepared by stepwise solid-state reaction.TG-DSC analysis result showed that the Al2W3O12 particles would be stable in the temperature range from room temperature to 900? with no phase transformation.The average thermal expansion coefficient of Al2W3O12 is-1.47×10-6K-1 from room temperature to 600?.2. Al₂W₃O₁₂/SiC_p/Al composites were fabricated by powder metallurgy?P/M?technology. According to the volume percentage of Al, 35% and 50%, two composites with different compositions were designed. 0%, 10% and 20%?volume ratio? Al2W3O12 powders were mixed into Si Cp/Al powders by ball milling. The composites were prepared by non-pressure sintering technology and vacuum hotpressing sintering technology, respectively. In order to avoid the chemical reactions, the sintering temperature was set to 600?. The time of non-pressure sintering was set to 1h and 3h, and the time of vacuum hotpressing process was set to 1h. Experiments results showed that the organizations of the composites were relatively uniform obtained by the two technologies. The porosity of the compositeobtained by non-pressure sintering for 1h was still a state of mechanical bonding.3. The density has increased significantly after sintering for 3h, but the porosity was still over 10%. The low density further influenced the comprehensive performances of the composite material. Compared with non-pressure sintering process, composite materials prepared by vacuum hotpressing process had relatively high density, with the porosity reached to 1%. The high density guaranteed the excellent comprehensive performances of the composites. The results showed that the thermal expansion coefficient of composites was effectively controlled by the introduction of negative thermal expansion Al2W3O12 particles. The thermal expansion coefficient of Al₂W₃O₁₂/SiC_p/Al?with 20vol% Al2W3O12 and 50vol% Al?prepared by hotpressing sintering is 4.68×10-6K-1, which is closer to the thermal expansion coefficient of chip materials. And the thermal conductivity of Al₂W₃O₁₂/SiC_p/Al is 91.735W/m×K. The thermal properties of composites can meet the demands applied in electronic packaging material.