Recent Low Temperature Solder of SnBi and Its Bonding Characteristics

A solder has been extensively used for long time in electronics packaging field, and there are various Sn-based lead-free solders such as Sn-Ag-Cu, Sn-Cu, Sn-Bi and etc. Recently, the low temperature solder, typically Sn- 58wt%Bi-X alloys, attract attention from industry because of flexible printed circuit board (FPCB) application and to avoid bending or warpage of big size electronic devices after high temperature soldering. In the Sn-58wt%Bi-X solder, basic important issues are melting temperature, wettability, microstructure, mechanical properties and etc. Specifically, the Sn-58wt%Bi-X solder receives much attention to improve the brittleness by grain refinement of Bi-phase. In this paper, recent studies about Sn-58wt%Bi-X solders were reviewed including melting temperature, microstructure and mechanical properties. Key words: Solder, Sn-58wt%Bi, Melting temperature, Microstructure, Mechanical property