Accelerated mechanical low cycle fatigue in isothermal solder interconnects

Abstract Properly assessing the underlying physics of failure is critical in predicting long term reliability electronic packages their intended field applications, yet traditional demonstration methods are complicated by time and cost considerations as well deterministic inadequacies when considering thermomechanical failures. In this work, an alternative testing apparatus associated protocol were utilized to provide clarity insight solder fatigue mechanisms at device scale; targeting rapid times with minimal while preserving life prediction accuracy. A test stand was developed allow for bi-directional application shear stress elevated steady-state temperatures. Utilizing mechanical force springs apply loads interconnects within devices, a given withstand repeated cycling studied using situ resistance monitoring techniques detect number cycles-to-failure (CTF) based on 30% increase criterion. mathematical method quantifying plastic work density (amount damage) sustained prior relying relationship between Hooke's Law damage deflection accurately assess strength tested devices.