Thermal Fatigue Behavior of SnAgCu Soldered Joints in Fine Pitch Devices

Abstract

Abstract This paper presents the fatigue life of fine pitch devices with SnAgCu soldered joints calculated by experiments and numerical simulation. Special test vehicles were selected with SnAgCu soldered joints for testing, and thus the fatigue life of the SnAgCu soldered joints was 1150 cycles under −55–125 °C test condition. On the other hand finite element code ANSYS was used to simulate the stress-strain response and fatigue life of lead free soldered joints based on two sorts of constitutive models: Anand equation and Wong equation, plus two life prediction models. It is found that the similar tendency can be seen in the stress history course curves based on these constitutive models, and the values of stress based on these constitutive equation are different from each other. Two life prediction equations, comparing with thermal cycling experiments, were employed to analyze the fatigue life of fine pitch devices with SnAgCu soldered joints under thermal cycling test. It is seen that the life calculated by fatigue life prediction equations with two creep mechanism based on Wong model coincide well with that of the test data, and the life calculated by Engelmaier-modified Coffin-Mason equation calculated based on Anand model is slightly higher than that of the actual result.