Air-stable silver-coated copper particles of sub-micrometer size

Silver-coated copper particles with various silver loading were prepared by a direct liquid-to-particle conversion process in spray pyrolysis reactor system. The prepared particles were completely densified at 900°C within a residence time of 2.1s and had core-shell structure, of which formation mechanism was proposed. The mean diameter of particles was 0.45μm. Copper particles of 20wt.% of silver loading were stable under air and 95% of copper remained as metallic copper even after 1month of exposure to air. This enhanced air-stability contributed to the enhanced electrical property of conductive film obtained from the coated particles. The conductive film obtained from 15wt.% of silver-coated copper particles had a sheet resistance of 1.2mΩsquare^-1. This low resistance resulted from the lack of oxide layer and low sintering temperature of silver layer.