Finite element analysis of vertical micro-probe considering Joule-heating effect

This paper describes structural analysis method considering Joule-heating for a reliable design of vertical probe. In this study, the tensile tests were performed to obtain mechanical properties of new material, Nickel-0.2%Boron. Specially, finite element analysis of probe considering Joule-heating effect is performed to analyse internal stress and contact force. To verify the result of finite element analysis, the manufactured probe is tested. The new material, Nickel-0.2% Boron has 95 GPa of the elastic modulus, 2261 MPa of the 0.2% proof strength and 2414 MPa of the tensile strength. First, the accuracy of the FE analysis was verified by comparing the contact force-over-drive (displacement) curves when compressing the probe to 75 μm without applied current between FE analysis and probe test. The temperature of probe by Joule-heating increases as the current is increased and consequently contact force and internal stress is increased by thermal expansion at 75 μm of over-drive. The result of finite element analysis coincides with the result of experiment but there is considerable error between the results over 0.36 A. From the FE analysis, it can be seen that the maximum stress is 360 MPa when there is no applied current and the maximum stress is 409 MPa when the applied current is 0.36 A. From this result, it was found that the applied current causes the reduction of fatigue life and a Curie temperature of Nickel was reached when a current of 0.36 A was applied.