Exploitation of a New Style Tin-bismuth Series Lead-free Solder

A new type of solder was fabricated by adding microelements into tin-bismuth series solder and then being rapid cooled.The microstructure and properties were investigated.Adding microelements restrain the segregation of bismuth,stopped bismuth forming into bulky crystal as strips,and increased the solid solubility of tin-bismuth solder.The solid solution strengthening improved the mechanical properties so that the shear strength came close to that of tin-lead eutectic solder.Rapid cooling apparently improved the microstructure of the solder,decreased its melting point and strengthened its soldering and mechanical properties which were close to those of tin-lead eutectic solder.