Microstructure and mechanical behavior of Sn-Bi-Cu and Sn-Bi-Ag lead-free solder alloys

Abstract

Sn-Bi solder alloys seem to be promising for replacing traditional Pb-based alloys. Low melting point and low relative costs characterize such alternative alloys, which are quite important factors to be considered for applications in microelectronics. However, unsuitable mechanical properties and low wettability are some drawbacks faced by such alloys. Microadditions containing Ag and Cu may improve these properties according to literature. The present work aims to evaluate the effects of adding Cu and Ag on the Sn-Bi based alloys during transient directional solidification. The results will include: mechanical properties, macrostructure, microstructure, thermal parameters during solidification, macrosegregation, X-ray diffraction. The expected large range of cooling rates will allow a complete evaluation of interrelations among microstructure and mentioned parameters to be performed.