Patent ID: 7681777

Claim:
A solder paste comprising an alloy powder blended with a flux, wherein the alloy powder is a powder mixture consisting of a plurality of powders each of which is a Sn—Zn based alloy powder not containing Ag or a Sn—Ag based alloy not containing Zn, each of the plurality of powders is selected from a Sn—Zn binary alloy powder, a Sn—Zn—Bi ternary alloy powder, a Sn—Zn—In ternary alloy powder, a Sn—Zn—Cu ternary alloy powder, a Sn—Zn—Sb ternary alloy powder, a Sn—Zn—Bi—In quaternary alloy powder, a Sn—Zn—Cu—Bi quaternary alloy powder, a Sn—Zn—Cu—In quaternary alloy powder, a Sn—Zn—Cu—Sb quaternary alloy powder, a Sn—Zn—Bi—Sb quaternary alloy powder, a Sn—Zn—In—Sb quaternary alloy powder, a Sn—Zn—Cu—Bi—In five-element alloy powder, a Sn—Zn—Cu—Bi—Sb five-element alloy powder, a Sn—Zn—Cu—In—Sb five-element alloy powder, a Sn—Zn—Bi—In—Sb five-element alloy powder, a Sn—Zn—Cu—Bi—In—Sb six-element alloy powder, a Sn—Ag binary alloy powder, a Sn—Ag—Cu ternary alloy powder, a Sn—Ag—In ternary alloy powder, a Sn—Ag—Sb ternary alloy powder, a Sn—Ag—Cu—Bi quaternary alloy powder, a Sn—Ag—Cu—In quaternary alloy powder, a Sn—Ag—Bi—In quaternary alloy powder, a Sn—Ag—Cu—Sb quaternary alloy powder, a Sn—Ag—Bi—Sb quaternary alloy powder, a Sn—Ag—In—Sb quaternary alloy powder, a Sn—Ag—Cu—Bi—In five-element alloy powder, a Sn—Ag—Cu—Bi—Sb five-element alloy powder, a Sn—Ag—Cu—In—Sb five-element alloy powder, a Sn—Ag—Bi—In—Sb five-element alloy powder, and a Sn—Ag—Cu—Bi—In—Sb six-element alloy powder, and the composition of the powder mixture consists of 5-10 mass % of Zn, 0.005-1.5 mass % of Ag, one or more selected from the group consisting of 0.002-1.0 mass % of Cu, 0.005-15 mass % of Si, 0.005-15 mass % of In, and 0.005-1.0 mass % of Sb, and a remainder of Sn.