Low-current resistance spot welding of pure copper using silver oxide paste

Silver oxide particles were used as an insert material to reduce the current necessary for resistance spot welding of pure copper plates. To form a conduction path for successful bonding, silver-oxide particles were reduced before bonding by preheating with a reducing solvent at 120 °C for 3 min to cover the particles with silver nanoparticles. At 2200 A, bonding could be achieved with silver-oxide particles, whereas bonding was not successful in welding experiments conducted without insert materials or with fine silver particles. Bonding was accomplished through the formation of a dense sintered layer. When such silver oxide particles are used for resistance spot welding, the joining is achieved by the high sinterability of the generated silver nanoparticles.