Effect of Prolonged Storage Up to 1-Year on Anand Parameters for SAC105 Leadfree Alloys

Abstract

Electronics in harsh environment such as downhole, automotive and avionics may be exposed to high temperatures in the neighborhood of 200°C and high strain rates of 1–100 per sec. Previously, electronic devices exposed to sustained temperatures of 150°C to 175°C at high strain rates have been shown to exhibit degradation. Electronics in automotive applications may be mounted under the hood or at engine resulting in prolonged periods of high temperature exposure followed by operation under vibration. The microstructure for lead free solder alloys constantly evolves when subject to thermal aging for longer period, which can cause degradation in mechanical properties of solder alloys. We need more reliable electronics that can operate in in harsh environments, including extremely high temperatures. Previous research has studied the effect of thermal aging on material behavior of lead-free alloys at different strain rates and different operating temperatures. There is lack of constitutive models in published literature to capture the mechanical deformation under transient dynamic loads at elevated temperature for aged assemblies. In this paper, effect of thermal aging (up to 1-year)on high strain rate material properties of lead-free SAC105 has been studied. Stress-Strain Curves were obtained using tensile testing. The thermal aged leadfree SAC105 solder alloys specimen have been tested at high strain rates (10–75 per sec)at elevated temperatures of (25°C-200°C). The SAC105 solder samples were subjected to isothermal aging at 50°C up to 1-year before testing. Effect of thermal aging on Anand parameters has been investigated. To verify the accuracy of the model, the computed anand parameters have been used to simulate the uniaxial tensile test. The Anand model predictive Stress-Strain data compared with experimental Stress-Strain data.