Electroless metallization of substrate through-holes and vias with a tin-containing ionic silver-containing catalyst

摘要

Walls of through-holes and vias of substrates with dielectric material are electroless plated with copper using tin-free ionic silver catalysts. Conductive polymers are first formed on the substrates by treating the substrates with a permanganate solution containing complexing anions followed by applying monomers, oligomers or conductive polymers to the substrate to form a conductive polymer coating on the dielectric of the substrate as well as on the walls of through-holes and vias of the substrate. A tin-free ionic silver catalyst is then applied to the treated substrate. Optionally, the tin-free ionic silver catalyst can include a ligand agent to form a coordination entity with the silver ions of the tin-free catalyst. The silver ions of the tin-free catalyst are reduced by the conductive polymer and then an electroless metal copper bath is applied to the treated substrate to copper plate the dielectric and walls of the through-holes and vias of the substrate.