Evaluation of electromigration in flip-chip solder joints

摘要

The flip-chip solder joint has become one of the most important technologies of high-densitypackaging in the microelectronics industry. But, electromigration has become a critical reliabilityissue in flip-chip technology. Because the dimensions of solder joints are expected to decrease andcurrent density is expected to increase.This study is about electromigration of flip-chip solder joints, we evaluated many kinds of solder ballssuch as SnAgCu, SnCu and so on in flip chip package. The lifetime against electromigration wasdefined the fail from the value of resistance with electric current reaches 1.5 times of that of initialresistance with electric current for.In solder bumps with electric current, since the atoms composed of the solder bump and UBM move inthe direction of electron flows, the IMC was accumulated on the anode side. Meanwhile, the IMCdisappeared in the cathode side, and the voids were formed. In the solder bumps without electriccurrent, the IMC gradually grew on both sides.SnAgCu had better lifetime than SnCu, and different time-to-failure caused by differentcrystallographic orientation of Sn. And various dopants in SnCu had a different EM lifetime eachother.