Low Melting Temperature Sn-Bi Solder: Effect of Alloying and Nanoparticle Addition on the Microstructural, Thermal, Interfacial Bonding, and Mechanical Characteristics

Abstract

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.

Microstructural Evolution and Tensile Testing of a Bi–Sn (57/43) Alloy Processed by Tube High-Pressure Shearing

“…Such a lamella-dominating structure exists after t-HPS for low numbers of turns as shown in Figure 1b,c. The absolute melting temperature, T m , of the Bi-Sn eutectic alloy is around 412 K and therefore the ambient room temperature is around 0.7 T m for the alloy [25][26][27][28][29]. It is widely recognized that the ductility of materials in tensile testing at elevated temperatures is related to the dislocation movement and/or grain boundary sliding behavior [30].…”

Review on the Integration of Microelectronics for E-Textile

“…In soldering, an additional material, called solder is used. The solders are soft alloys of lead (Pb), tin (Sn), or sometimes silver (Ag) that are used to join the metallic electrical components with the textile substrate, with Sn42Bi 58, a suitable alloy for textiles with melting point at 138 °C [ 83 ]. Soldering achieves good electrical contact [ 84 ].…”

Emerging Interconnection Technology and Pb-Free Solder Materials for Advanced Microelectronic Packaging

“…The next three articles provide a thorough review of the various emerging interconnection materials and technologies for microjoining applications, such as brazing fillers, low-temperature Sn-Bi solders, TLP bonding, and wire bonding technology for power electronics devices. Kang et al [3] overview historical developments in low-meltingtemperature solders, emphasizing Sn-Bi composition, in particular. The authors review the developments in Sn-Bi solders, the effects of nanoparticles incorporated into the Sn-Bi solder matrix on the morphology, shear strength, and wettability.…”