This study investigates electromigration study of eutectic SnPb flip-ch.ip .solder joints on ceramic substrates. The under bump metalltzatlon (UBM) structure consists of 5-J.lIll Cu / 3-J.lIll Ni under bump metallization (UBM). Under the current stressing by 0.9A at 150°C, we did not find void formation but a large amount of intermetallic compound (IMC) ofCU
were formed when the bump resistance increased 10 mΩ. Three-dimensional electrical simulation by finite element analysis was carried out to simulate the current density distribution in solder joints with slit Cu traces. It is found that the current density was almost uniformly distributed in solder joint for this structure. It is found that the bump resistance only increases 0.07mΩ when half of the solder bump was transformed into CU
IMC. The reason for the low crowding effect In the solder joints will be discussed in the conference.