Effect on Shear Strength and Hardness Properties of Tin Based Solder Alloy, Sn-50Bi, Sn-50Bi+2%TiO₂ Nanoparticles

Abstract

Solder alloys are important joining medium widely used in the electronics industry to connect components to printed circuit board PCB. The Sn-Pb solder alloys have been the cornerstone medium used for a long time. Unfortunately, the use of Pb was banned by the European Union due to the harmful environmental and health issues with Pb. Therefore, in this study, the Sn-50Bi and Sn-50Bi+2%TiO2 nanoparticles lead-free solder alloy is investigated based on their shear strength, Vickers hardness, and melting temperature. The investigation shows that the hypo eutectic Sn-50Bi has a low melting temperature of approximately 145°C, and the 2%TiO2 nanoparticles reinforced Sn-50Bi has a melting temperature of around 182°C, which is lower than the traditional Sn-Pb (Tm=183 °C) and Sn-Ag-Cu (Tm=227°C). Furthermore, the developed Sn-50Bi had a Vickers hardness and shear strength of 26.81 HV and 40.78 MPa respectively, higher than the other leaded and lead-free solders. However, after the reinforcement, the hardness increased by 12% (30 HV) and a slight increase of 2.5% (42.4MPa) in shear strength. Overall, the addition of the TiO2 nanoparticles showed a clear influence on the Sn-Bi properties. The results obtained from this study seem satisfactory to the electronic industry and the environment.

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

“…Sn-Bi eutectic composition is known as Sn-56.97%Bi and its melting point as 138.8 • C by NIST (National Institute of Standards and Technology), and Sn-57%Bi and 139 • C in the phase diagram by the ASM International. However, in many publications, Sn-58%Bi with a melting point of 138-139 • C is also used as the eutectic composition [19,38,39]. Anyway, this eutectic melting point may have slight variations depending on the heating rate of Sn-58% alloy.…”