The authors developed a test system to easily measure the fatigue life of wire bonding. The test specimens were prepared by bonding Al wires onto Al electrodes with current applied and voltage measured area. By applying a 10 A square-wave current to them, the current application path was heated and a repetitive thermal load of 110－240℃ was applied to the wire bonding part. At the same time, we attempted to measure the thermal fatigue nondestructively by measuring the resistance change ratio（ ΔR/R0） of the wire bonding part using the 4-terminal method. As a result of the verification, it was found that Δ R/R0 and crack length of wire bonding parts are closely correlated. Then, the observed fatigue lifetime was close to those predicted from conventional thermal shock test results. These results indicate that the developed system is a reasonable lifetime measurement technique and that this system has the potential to efficiently collect the fatigue life of wire bonding, which is necessary for the reliability design of power devices.
