In-situ study on the formation and evolution behavior of voids at the interface during soldering process by synchrotron radiation real-time imaging technology

In this paper, by using the synchrotron radiation real-time imaging, the growth of gas bubbles on solid-liquid interface during the soldering process was investigated. It was proved that the formation and growth of the bubbles was a process of heterogeneous nucleation. During the soldering heating insulation stage, the bubbles volume increased first and remained unchanged afterwards. When there were more than one bubbles, the annexation process was happened among the adjacent bubbles, the larger bubbles were pulled to the smaller ones. The bubbles volume remained unchanged during the cooling stage. At the same time, the dissolution of the Cu substrate and the growth of the IMCs were influenced by the bubbles.