Low-Resistance Soldered Joints of Commercial 2G HTS Wire Prepared at Various Values of Applied Pressure

• Published in: IEEE transactions on applied superconductivity 2018-06, Vol.28 (4), p.1-4
• Main Authors: Balashov, Nikolay N., Degtyarenko, Pavel N., Ivanov, Sergei S., Kopylov, Sergey I., Gorbunova, Daria A., Molodyk, Alexander A., Samoilenkov, Sergey V., Sytnikov, Viktor E., Zheltov, Vladimir V.
• Format: Article
• Language: English
• Subjects: 2G HTS wire; Conductivity; critical current degradation; Critical current density (superconductivity); Degradation; High-temperature superconductors; Integrated circuits; low resistivity; solder joints; Soldering; Wires
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2018.2806388

In this study, we prepared soldered joints of 2G HTS wires from three different manufacturers: SuNAM, SuperPower, and SuperOx. We used Pb 39 Sn 61 solder and varied the pressure applied on the joint during soldering in the 3.9-10.5 MPa range. We found that for all samples, joint resistivity decreased with increasing applied pressure. Practically important, very low joint resistivity values in the 10-15 nΩ·cm 2 range were reproducibly achieved in joints made with SuperPower and SuperOx wire. Resistivity of joints made with SuNAM wire was rather high, in the 40-90 nΩ·cm 2 range. No degradation in I c across joints occurred in joints made at up to 8 MPa applied pressure. In joints made with SuperOx wire at applied pressure above 8 MPa, there was I c degradation comparing to the initial I c of individual wires before joining. We speculate on the possible reasons for the different resistivity and I c degradation behavior of joints made with wires from different manufacturers.