Superconducting solders are widely used as joining material to connect superconducting wires such as Niobium-titanium (NbTi) and Niobium-tin (Nb3Sn) wires in commercial superconducting magnet applications. The physical and superconducting properties of the solder materials are very important since it influence the overall performance of the joint during service. Pb-Bi solder alloy widely used due to their good properties suitable for the superconducting application, however, the restriction on the use of Pb in industry lead to the development of new Pb-free solder material. This paper reviews the superconducting Pb-free solder alternatives, including In-Sn based solder. Besides that, the effect of bismuth (Bi) and antimony (Sb) addition to the binary In-Sn solder alloy were also discussed.
