Fatigue crack propagation behavior of lead-free solder joints under high-strain-rate cyclic loading

The fatigue crack growth in a solder joint was monitored during dynamic cyclic loading induced by mechanical shock. Crack growth was tracked via measurement of tiny resistance changes in the solder joint coupled with computational simulations of cracked joints. The unique fatigue characteristics observed are an insignificant crack nucleation period and a distinctive growth pattern for bulk solder cracks. Crack growth accelerates upon movement of the crack into intermetallic regions, a common occurrence for lead-free solders under high material strain rates.