Early stage of material movements in eutectic SnPb solder joint undergoing current stressing at 150℃

摘要

X-ray fluorescence spectroscopy was used to study movements of Sn and Pb in the eutectic SnPb solder joint undergoing electromigration with a current density of 10~4 A/cm~2 at 150℃. During early stages of current stressing, Sn moves toward the anode faster than Pb. However, on continued application of current stressing, both Sn and Pb will continue to accumulate at the anode. Such accumulation of conductive species facilitates the formation of hillock with associated valley near the cathode.