The present work investigated the effect of in-situ Cu solubility on electromigration behavior in the current-stressed Cu/Sn/Cu microjoint. Firstly, we deduced that the in-situ Cu solubility in a current-stressed Cu/Sn/Cu microjoint can be determined by the magnitude relationship between the dissolution Cu flux and the electromigration Cu flux in the current-stressed Sn matrix. And, the in-situ Cu solubility in the current-stressed Sn solder matrix governs the electromigration-induced failure modes of the microCu/Sn/Cu solder joints. If the dissolution Cu flux is larger than the electromigration Cu flux, the equilibrium Cu solubility can be maintained in the Sn solder matrix, and the electromigration of the Sn host atoms can be retarded. Thus, no electromigration-induced voids could occur in the Sn solder matrix. Only electromigration-induced Cu-pad consumption could be observed at the cathode Sn/Cu interface under this condition. On the other hand, if the dissolution Cu flux is smaller than the electromigration Cu flux, the Cu solute in the Sn matrix phase is depleted by the electromigration Cu flux. Then, the Sn host atoms would electromigrate toward the anode side. Void formation occurs in the Sn matrix phase near the cathode interface.Using the magnitude relationship between the dissolution Cu flux and the electromigration Cu flux, the boundary parameters (critical temperatures and current densities) defining the electromigration-induced failure modes can be obtained. With the obtained boundary parameters, an electromigration-induced failure diagram is constructed, which can distinguish and predict the electromigration-induced failure modes (void formation and Cu-pad consumption) in the microCu/Sn/Cu solder joint.
|Journal||Journal of Applied Physics|
|State||Published - 7 Sep 2017|