Abstract
Gold particles of 60-80μm in diameter are welded to a gold substrate of 300μm in thickness by applying high voltages of 10kV to a tungsten needle-like probe which is in contact with the particle. The joint is strengthened by an electric discharge from the probe positioned 20μm above the particle. After welding, the joint was fractured by tensile loading, and the fractured load is measured by a strain gauge. The welding area is estimated from the observation by an SEM and a laser microscope after the joint is fractured. The fracture load is plotted against the welding area, and effects of several factors on the strengthening are discussed. The fracture load increased 6 times or more by flowing N_2 gas during non-contact welding. While the effect of preheating during the non-contact welding is not clear. The fracture stress is greatly scattered, because of the estimation error of welding area and distribution of stress concentration factor.
