SOLDER PASTE AND PROCESS

摘要

A solder paste comprises a lead-free solder powder, a flux and an active additive in the flux. The active additive comprises a material that scavenges metal oxide from molten solder, is a stable liquid at reflow soldering temperature, and has the ability to assimilate oxide of at least one metal in the solder. A preferred active additive is dimer acid present in the range of from 0.5 to 2.5% percent by weight of the paste. Sound joint are obtained when the paste is used in a reflow soldering process wherein the peak reflow temperature is preferably less than 245°C.