Metallographic Examination of Solder Joints on Surface‐mounted Components

Some special characteristics of solder joints made between surface mounted electronic components and circuit boards as compared with conventional wave soldered lead‐through joints are discussed, and the types of defects to be expected are listed. Following a description of metallographic methods suitable for examining surface soldered joints, some metallographic features, both normal and defective, of solder joints between chip carriers and substrates are illustrated and discussed. The features include porosity, intermetallic phases, solder microstructure, and low cycle fatigue cracking resulting from temperature cycling.