Modification of Sn58Bi solder based on graphite

Abstract

A novel composite solder paste with 0·07 wt-% graphite addition was fabricated. The mechanical properties of matrix solder and composite solder alloys were tested using a kind of miniature joint. The results showed that the tensile strength of the Sn58Bi+graphite composite solder joint declined slightly compared with the Sn58Bi solder joint. However, the elongation of the Sn58Bi+graphite composite solder joint was ～13 times as much as that of the Sn58Bi solder joint. Stress relaxation method, which was used to test the creep performance, was verified by nanoindentation method. The result showed that the stress relaxation method was suitable for creep testing. The creep testing results of Sn58Bi and Sn58Bi+0·07 wt-% graphite solder alloys showed that the anticreep performance of Sn58Bi was improved by the addition of graphite.