High-strength solder joint

摘要

A soldering method achieving a high-strength joint between a solder and an nickel/gold alectroless plated surface is disclosed. The nickel/gold electroless plated layer is soldered using a solder including tin (Sn), silver (Ag), and copper (Cu). At a solder joint, a layer sturcture of nickel layer / intermetallic compound layer / solder layer is formed. The intermetallic compound layer is composed mainly of tin (Sn) and copper (Cu),and further including nickel (Ni). The intermetallic compound layer has cauliflower-shaped surfaces formed in a solder-layer's side thereof.