Silver deposition on a polymer substrate catalyzed by singly charged monodisperse copper nanoparticles.

Aerosol deposition of singly charged monodisperse copper nanoparticles was used to catalytically activate a polymer substrate for electroless silver deposition. An ambient spark discharge was used to produce aerosol copper nanoparticles, and the particles were electrostatically classified at an equivalent mobility diameter of 10 nm, using a nanodifferential mobility analyzer. Deposition of the copper particles onto the surface of the substrate was enhanced by thermophoresis. The copper-deposited substrate was then immersed in a Ag(I) solution, resulting in the electroless deposition of silver (∼17 μm line width) on the previously deposited copper (∼12 μm line width, using a shadow mask with a 100 μm in width patterned stripe). The arithmetic mean roughness and electrical resistivity of the silver pattern were 44.7 nm and 7.9 μΩ cm, respectively, which showed an enhancement compared to those from the nonclassified copper particles (roughness = 162.2 nm, resistivity = 13.3 μΩ cm), because of a more-uniform copper deposition.