Evolution of Propensity for High Strain-Rate Damage Accrual in Doped and Undoped SnAgCu Lead-free Solders in Temperature Range of -65°C to +200°C after 1-Year Sustained High Temperatures Exposure

To ensure the reliability of high-performance electronics systems, constitutive models are crucial. Predictive models are particularly necessary for electronic equipment that operates in harsh environments, where extreme temperatures ranging from -65°C to +200°C may cause significant out-of-plane deformation in board assemblies due to shock, vibration, or transient loads. Automotive under-hood and aerospace electronics may require sustained exposure to high temperatures of 150-200°C and may go through random mechanical shock and vibration. Additionally, electronics may be stored in non-climate-controlled enclosures for prolonged periods before deployment. In order to mitigate the adverse effects of sustained high-temperature exposure, the industry has experimented with adding dopants to SAC solders. This paper studies the effects of dopants, including Nickel and Bismuth, on doped alloys such as SAC-Q, SAC-R, M758, and SAC305 solder. The study examines the strain-rate range of 1–100 per second and the temperature range of -65°C to + 200°C after one year of sustained exposure to 50°C and 100°C storage temperatures. The Anand model's accuracy has been quantified by comparing experimentally measured data with predicted data computed using the model's constants. Anand parameters have been computed and implemented in an FE analysis framework to simulate drop events for a ball-grid array package on a printed circuit board assembly, determining hysteresis loops of stress vs strains and plastic work density. The study also explores the evolution in hysteresis loops and PWD.