Effect of Alloy Composition and Aging on the Survivability of Leadfree Solders in High Temperature Vibration in Automotive Environments

Abstract

Current trends in the automotive industry point to increasing role of electronics for vehicle control, safety, efficiency and entertainment. Examples include lane-departure warning systems, collision avoidance systems, vehicle stability systems, and drive assist systems. Many of the automotive electronics systems are located under the hood of the vehicle mounted directly on engine or on transmission with sustained exposure to temperatures greater than 150°C in conjunction with vibration. Solder joint fatigue is a dominant failure modes under high-temperature vibration. Industry migration to lead-free solders has resulted in a proliferation of a wide variety of solder alloy compositions many of which are based on formulation of Sn, Ag and Cu. While it is well known that solder interconnects, accrue damage much faster when vibrated at elevated temperatures, the models for assessment of life under simultaneous temperature and vibration are scarce. State-of-art reliability models for solder joints focus on single stresses of vibration or thermal cycling. There is need for models for evaluating the survivability of leadfree solder assemblies to ensure 10-years, 100,000 miles life in automotive environments. In this paper, a new model has been proposed for life prediction of electronics under simultaneous temperature-vibration.