Void ripening in Cu-Cu bonds

Cu-Cu joints have potential in high performance electric product. Although the voids in the bonding interface was observed, there was no report on the size distribution and evolution of voids due to ripening. In this paper, the void size distribution under 200 °C for 30, 60 and 120 min is obtained by a specific direction. The average void diameter is 49 nm, 70 nm, and 96 nm for the joint annealed for 30, 60, and 120 min, respectively. A simple kinetic model of ripening is developed, and the relationship between radius and annealing time is in good agreement with experimental data.