Abstract
This paper discusses the mechanical properties, thermo-mechanical fatigue (TMF) and isothermal low cycle fatigue (LCF) life evaluation of Sn-0.7Cu-0.3Ag. Sn-0.7Cu-0.3Ag is proposed as a low-cost alternative material because it contains a low proportion of Ag. Static tensile test were conducted to determine the mechanical properties of Sn-0.7Cu-0.3Ag at various temperatures. As solder joints in electronic devices undergo cyclic TMF damage caused by the mismatch of the thermal expansion coefficients of different materials, TMF tests were conducted in in-phase and out-of-phase conditions in the temperature range of 253 K-353 K and isothermal LCF tests were conducted at 253 K and 353 K.
The authors have previously proposed a method of evaluating the TMF and LCF lives of solders based on the energy parameter calculated as multiplication stress and strain in tension including consideration of the mean stress amplitude. In this study, we confirmed an application of the evaluation parameter to the TMF and LCF life of Sn-0.7Cu-0.3Ag.
