Effect of Thermal Aging on the Evolution of Anand Parameters for SAC105 Leadfree Alloys Operating at Cold Temperatures down to -55 °C

Abstract

Automotive and defense electronic systems may be subjected to low and high temperatures (-55 °C 150°C) and high strain rates (1-100 per sec) during storage, operation and handling which can contribute to the failures of electronics devices. Temperatures in these applications can varies between -55 to 200°C. The microstructure evolution due to change in operating temperature and thermal aging can cause degradation in mechanical properties of Leadfree solder alloys. So, we need more reliable lead-free solder alloys which can survive in these extreme harsh environments. Previously, effect of thermal aging on mechanical properties and Anand model parameters for SAC (SAC105, SAC305 and SAC-Q) solder materials have been studied at different high strain rates (10, 35, 50, 75 /sec) and elevated temperature (25°C-200°C) for pristine samples and aged samples up to 1 year have been studied and observed that SAC alloys are sensitive to strain rate, operating temperature and thermal aging. [Lall 2013-2019]. However, there are no data available in published literature for SAC105 solder alloy at high strain rate at low operating temperature. In this paper, pristine and thermally aged (up to 6 months) leadfree SAC105 solder alloy has been studied at low operating temperatures (-65°C-0°C) at high strain rates (10-75 per sec). Stress-Strain data have been measured using tensile tests. Microstructural Evolution for SAC105 solder alloys has been explored induced due to thermal aging. Experimental data has been fit to Anand Viscoplastic model. Evolution of Anand Model parameters for SAC105 solder has been investigated. To verify the accuracy of the model, the computed parameters from experimental data have been used to simulate the uniaxial tensile test. A good correlation was found between experimental data and model predicted data.