Determination of creep parameters of 80Au/20Sn solder by nanoindentation

80Au/20Sn solder alloy was widely used in micro-electronic and optoelectronic packaging, the creep property of the alloy was very important for longer operating lifetime of apparatus. The creep parameters describing the creep behaviour were of great importance for developing a constitutive model and to analyze the creep mechanism. In this study, nanoindentation tests were performed using constant loading rate/constant load method at different loading rates and temperatures. The elastic modulus and hardness were acquired using the Oliver-Pharr method after the contact areas were modified based on the semi-ellipse method for the pile up indentation. The difference of the creep stress exponent and creep activation energy obtained between nanoindentation test based on the concept of "work of indentation" and the conventional uniaxial tensile creep tests was below 13%. It implied that nanoindentation test and analysis method could be used to evaluate the creep parameters of solder alloys to some extent.