High current pressure contacts to Ag pads on thin filmsuperconductors

High current, low resistance, nonmagnetic, and nondestructive pressure contacts to Ag pads on YBa₂Cu₃O_7-δ (YBCO) thin film superconductors were developed in this study. The contact resistance reported here includes the resistance of the current lead/Ag pad interface, the Ag pad/YBCO interface, and the bulk resistance of the contact material. This total contact resistance is the relevant parameter which determines power dissipation during critical-current measurements. It was found that regardless of the optimization of the Ag pad/YBCO interface through annealing, a pressure contact can yield a lower total resistance than a soldered contact. The lowest resistance obtained with pressure contacts was 3 μΩ (for a 2×4 mm ² contact). These contacts may be useful for many different high temperature superconductor (HTS) studies where high-current contacts with low heating are needed