Characterization of Additively Formed Copper Layer by Blue Laser-Sintered Copper Nanoparticles

We investigated the sintering of copper nanoparticles by blue diode laser in atmosphere to apply copper nanoparticles as preformed insert-materials for die bonding of power devices. Copper paste consisting of copper nanoparticles, ethylene glycol, and polyvinylpyrrolidone was formulated. The surface morphology and oxidation state of the sintered copper were evaluated. We found that the higher the laser power, the more the necking between copper particles, and that blue laser sintering successively suppressed oxidation of copper.