Soldering paste and flux

摘要

The object of the present invention is to provide a solder paste that enables to form a surface mounting structure for electronic components that exhibits crack resistance in a solder joint section even in 100 heat-shock cycles at −40° C. to 150° C. as required for use in the vicinity of engines for vehicular applications. A flux including an amine halogen salt and a dicarboxylic acid is kneaded with a Sn—Ag—Bi—In alloy powder. As a result, a solder paste exhibiting long continuous printability, little occurrence of solder balls, and excellent joining ability with no cracking in 100 heat-shock cycles at −40° C. to 150° C. is obtained.

主权项

1. A solder paste prepared by kneading a Sn—Ag—Bi—In alloy powder and a flux, wherein
the Sn—Ag—Bi—In alloy powder has an Ag content of 0.1 wt % to 5 wt %, a Bi content of 0.1 wt % to 5 wt %, and an In content of 3 wt % to 9 wt %, with a balance being Sn and unavoidable components; and components of the flux include an amine halogen salt and a dicarboxylic acid, wherein the dicarboxylic acid has an unsaturated double bond between carbons in a molecular frame or 2 or 3 carbon number in a molecular frame.