Interfacial reaction, shear behavior and microhardness of Cu-Sn TLP bonding joints bearing CuZnAl powder for 3D packaging

The process of transient liquid phase bonding to form intermetallic compound solder joints can effectively achieve 3D chip stack interconnection. However, there are a large number of void defects in IMC solder joints due to the rapid reaction between elements, which reduces the reliability of the chip stack interconnection. In this study, the interfacial reaction, shear behavior and microhardness of Cu-Sn TLP bonding joints were investigated by adding 0.5 wt% CuZnAl powder into the pure Sn interconnect solder. Adding CuZnAl powder can remarkably retard the growth of intermetallic compound and voids in the bonding joints, which is attributed to the fact that CuZnAl powder can reduce the concentration gradient of Cu in the interface region. Compared with the Cu-Sn-Cu bonding joints, the shear strength of composite bonding joints was increased by 12%-19.7%, and the microhardness of composite bonding joints was also improved.

Automated summary

Adding CuZnAl powder can significantly retard the growth of intermetallic compound and voids in the bonding joints, leading to increased shear strength and microhardness in composite bonding joints compared to Cu-Sn-Cu bonding joints.