Generation of near eutectic phase layer in Sn-15Bi solder joint during electro-migration

Abstract The electro-migration test of Sn-15Bi solder joint was conducted at 150 °C with a current density of 160 A/cm 2 . The near eutectic phase layer thickening as the extending of electro-migration time was observed on the anode side interface of Sn-15Bi solder joint. The Bi fraction of cathode side reduced as the increase of electro-migration time. The Bi atom of near eutectic phase layer was from solid solution Bi atom in β-Sn phase. The diffusion of Bi atom was up-hill diffusion under the effect of electron flow.