Thermo-mechanical Modelling of Cu Wire Parallel Gap Micro-resistance Welding Process

In recent years, parallel gap resistance welding has been widely applied in 3D packaging devices. But for the interconnection of microscale wire and nanoscale plating, the current density and the temperature field during welding process and the stress and strain distribution in the reliability testing are difficult to measure experimentally. Numerous studies show that finite element method (FEM) provides a way to obtain these hard-to-get data. In this paper, a 1: 1 finite element model was built to simulate the welding process and three reliability tests under thermal shock, random vibration and electric heat aging environment. The results indicated that the temperature at the center of conduct surface was the highest during welding procedure, which was 1211 K and was lower than the fusion point of interconnect materials. The welding method was solid-phase bonding. In the thermal shock experiment and the electric heat aging experiment, the neck of the joint was the weakest part. And in the random vibration analysis, where the stress was the biggest was the interface between the neck of wire and the joint. The maximum equivalent stress was 0.77 MPa which was far less than the failure intensity of welding spot.