Sn-based lead-free solders such as Sn-Ag-Cu, Sn-Cu, and Sn-Bi have been used extensively for a long time in the electronic packaging field. Recently, low-temperature Sn-Bi solder alloys attract much attention from industries for flexible printed circuit board (FPCB) applications. Low melting temperatures of Sn-Bi solders avoid warpage wherein printed circuit board and electronic parts deform or deviate from the initial state due to their thermal mismatch during soldering. However, the addition of alloying elements and nanoparticles Sn-Bi solders improves the melting temperature, wettability, microstructure, and mechanical properties. Improving the brittleness of the eutectic Sn-58wt%Bi solder alloy by grain refinement of the Bi-phase becomes a hot topic. In this paper, literature studies about melting temperature, microstructure, inter-metallic thickness, and mechanical properties of Sn-Bi solder alloys upon alloying and nanoparticle addition are reviewed.

Transient liquid phase (TLP) bonding is a novel bonding process for the joining of metallic and ceramic materials using an interlayer. TLP bonding is particularly crucial for the joining of the semiconductor chips with expensive die-attached materials during low-temperature sintering. Moreover, the transient TLP bonding occurs at a lower temperature, is cost-effective, and causes less joint porosity. Wire bonding is also a common process to interconnect between the power module package to direct bonded copper (DBC). In this context, we propose to review the challenges and advances in TLP and ultrasonic wire bonding technology using Sn-based solders for power electronics packaging.