Electromigration behavior of micro Sn bump under pulsed DC

Pulsed electromigration (EM) was performed for flip-chip solder bump. Pulsed EM was conducted with current density of 5.2 ~ 7.1 times 10⁴ A/cm² at 160degC. DC EM was also performed at 3.6 ~ 4.7 times 10⁴ A/cm² for comparison. Reduction of Joule heating was monitored when pulse current is applied. The life times of pulsed EM samples are larger than those of DC EM samples. The current density exponent for 1 Hz pulsed EM is 1.42 and that of DC EM is 2.25. The life time of pulsed EM was successively converted into that of DC EM by considering Joule heating temperature and the duty factor. Failure time of pulsed EM increases with increasing frequencies around 2 Hz.