Cu-Sn alloy metallization of polymer substrate through reduction-diffusion method using ionic liquid bath at medium-low temperatures

Abstract

Cu-Sn speculum alloy metallization of a non-conductive epoxy substrate was demonstrated through successive electrochemical processes: (i) electroless Cu deposition on the substrate and (H) electrochemical alloying of the resulting Cu layer with Sn through a reduction-diffusion method using an ionic liquid bath at 150°C. The resulting Cu-Sn alloy layer, composed of Cu6Sn 5 and/or Cu3Sn phases, was compact, smooth, and adhesive. Dependence of the intermetallic phases on alloying potential and time was examined to discuss the alloy formation mechanism, demonstrating that Cu-Sn alloy layers composed of desired phases could easily be prepared by controlling these parameters.