Evolution of intermetallic compound at the interface between AuSn solder and metallization layer

This paper investigates the intermetallic compound on the interface between AuSn solder and Au or Au/Ni metallization layer after laser soldering by SEM and EDX analysis. The effects of laser power and heating time on the evolution of intermetallic compounds on the interface are discussed. The results show that the components of intermetallic compound depart from the eutectic arrest due to Au dissolving quickly into the solder near the interface and forming a stable Au₅Sn at the interface on the condition of laser heating and cooling quickly. With the increase of laser power and heating time, the undissolved Au layer becomes thinner and the Au₅Sn grows into the solder.