抄録
This paper presents mining the worst thermal fatigue life of solder joints on chip components used in vehicle electronics. Typical 36 cases with various solder shapes were examined. Thermal fatigue life to not only crack initiation but also crack propagation was evaluated by using the finite element method. When a crack propagates along the side of the component, the failure life in lead-free solder joints varies within 20 %. On the other side, when the crack propagates into a fillet of solder, the fatigue life drops. Since there is an interaction between two solder joints on the chip component, asymmetrical structure also affects the fatigue life. The worst fatigue life show the 80 % decrease compared with a standard model. It means that the shape of solder joints should be designed to control the failure mode.
