Effect of minor scandium addition on the microstructure and properties of AI-50Si alloys for electronic packaging

摘要

Al—50Si alloys for electronic packaging were prepared by gas atomization following hot press sintering, and the influences of adding minor Sc (0.3%) on microstructure and mechanical and thermo-physical properties were studied. The Si phase exhibits a semi-continuous network structure with an average size of 15-20 μm in the alloys with and without Sc addition. Transmission electron microscopy observation indicates that a fine spherical Sc-rich particle distributes at the interface between the Al matrix and Si phase in the Al-50Si-Sc alloy, which is further identified as AlSi_2Sc_2 (V-phase). The tensile strength, flexural strength, and hardness of the Al-50Si alloy are improved by 16.2%, 8.9%, and 14.7%, respectively, with the introduction of Sc. However, the coefficient of thermal expansion and thermal conductivity decreases slightly in the Al-50Si-Sc alloy as compared with the Al-50Si alloy. The increased strength is mainly attributed to the formation of fine spherical AlSi_2Sc_2 phase which strengthens the Al matrix.