Effect of Sn grain orientation on formation of Cu6Sn5 intermetallic compounds during electromigration

The effects of Sn orientation and grain boundary misorientation on formation of Cu-Sn intermetallic compounds (IMCs) during electromigration were investigated. Significant anisotropic diffusion of Cu in Sn grains was observed. Interfacial Cu-Sn IMCs may grow rapidly, dissolve, or remain intact, depending on the angle of c-axis of Sn grains with the electron flow. As shown in the figures below, the Sn grains on the right-hand side transformed into IMCs; however, the grain on the left-hand side had less IMC formation due to large angle between c-axis of Sn grain and electron flow.60