Solder paste

摘要

A solder paste comprises a lead-free solder alloy powder and a flux and is suitable for use in reflow soldering of electronic parts at a soldering temperature of 230° C. or below with minimized damage to the electronic parts to form soldered joints of good bond strength. The solder alloy powder is a mixture of from 10 to 30 vol % of a first powder of an Sn-Bi alloy consisting essentially of 10-45 wt % of Bi and a balance of Sn and from 70 to 90 vol % of a second powder of an Sn-Zn alloy consisting essentially of 9-15 wt % of Zn and a balance of Sn. The mixture gives an alloy having a composition upon melting which consists essentially of 7-11 wt % of Zn, 1-5 wt % of Bi, and a balance of Sn.