Induction Soldering of Coated Conductor High-Temperature Superconducting Tapes With Lead-Free Solder Alloys

In this paper, the joints of rare earth barium copper oxide high-temperature superconducting (HTS) tapes with surrounding copper stabilizer were prepared by induction heating. The HTS tapes with the overlap of 35 mm were joined by using two types of Sn-Ag-Cu solder alloys: near eutectic and hypoeutectic. The quality of the joints has been studied by measuring the current-voltage curve, from which the joint electrical resistance, critical current, and n-value were determined. The electrical characterization has been followed by microstructural investigation of the solder tape interface by using scanning electron microscopy. The chemical composition of the solder alloys influenced the joint quality. Furthermore, there is a notable difference in microstructure between induction soldered joints and reflow soldered joints by electrical resistivity furnace.