Investigation of creep stress exponent of 80Au/20Sn solder by nanoindentation

Eutectic 80Au/20Sn solder alloy is widely used in high power electronics and optoelectronics packaging in which the creep property of the solder joint is essential to meet the global demand for longer operating lifetime.The creep stress exponent describing the creep behaviour of the material is often obtained by conventional tensile or compressive creep tests.However, the testing methods are often tedious.In this study, the creep stress exponent value determined by nanoindentatoin tests based on the concept of "work of indentation" agrees with that determined by uniaxial tensile and compressive creep tests.It indicates that such nanoindentaion tests and analysis provide a cheaper and more convenient method to evaluate the creep properties of solder alloys.To some extent, the results can be explained by the similarities and differences among the testing methods.