Thermomigration-induced failure in ball grid array solder joint under high current stressing

In this work, rapid failure of a few minutes was observed in real ball grid array solder joints under high current density (8 × 10 3 and 1 × 10 4 A cm −2 ) at room temperature. For each test condition, the failure solder joint was detected at the same position of the daisy chain by computed tomography technology. Furthermore, the open failure for all solder joints was caused by the chip side (anode side) Cu dissolution. Microstructure evolution for a pair of electrically connected solder joints was investigated. In both solder joints, Cu atoms on the chip side were dissolved to the board side with the formation of intermetallic compound particles in solder matrix. Finite element simulation was introduced to calculate the current density, temperature, and heat flux distribution. The temperature gradient along the direction of Cu migration in solder joint was developed due to the accumulation of Joule heating. Thermomigration was confirmed as the dominant mechanism of chip side Cu dissolution.