Soldering of Bi-2223/Ag high temperature superconducting tapes with Sn–Pb–Bi–Ag alloy paste

Soldered joints of Bi-2223/Ag-sheathed high temperature superconducting multifilamentary tapes were fabricated using 63 wt.%Sn–34 wt.%Pb–1 wt.%Bi–2 wt.%Ag paste. The soldered joints were observed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Moreover, the electrical properties of joints were evaluated by current–voltage curves, and the tensile strengths of the joints were also tested. The results show that the soldered joint consists of Ag sheath – Ag3Sn compound layer – PbSn2 and Ag3Sn solder layer – Ag3Sn compound layer – Ag sheath. The joints are obeyed with Ohms Law and the magnitude of the joint resistance, which deceases with the increase of the overlap length, can reach the order of 10−8 Ω. The tensile strength of the joints with a brittle fracture mode is a little lower than that of the original tapes.