Critical Current Degradation of Coated Conductors Under Soldering Conditions

Abstract

The critical current degradation of coated conductors was investigated at 77 K s.f., after heating the samples in a solder bath to temperatures between 200 °C and 300 °C for durations between 30 s and up to 2 h to simulate possible soldering conditions. We found that the critical current degradation is strongly dependent on temperature and time, but independent from the number of thermal cycles. At 225 °C for 10 min a degradation of about 5% was measured. At 300 °C for 10 min the degradation was about 45%. Slight variations among different manufacturers were observed. Across production batches of the same manufacturer no variations were found for tapes of the same structure. Slight variations of tapes with different stabilizer thicknesses were detected after heat treatment.