Electroless Copper Plating onto Polyimide Using Polymer Nanosheet as a Nano-Adhesive

Abstract

In this paper, we describe a technique to prepare a copper layer on polyimide film using a polymer nanosheet as a nano-adhesion. We employ two kinds of functional polymer nanosheets: one works as an adhesion layer and the other works as a template layer to adsorb gold nanoparticles, which works as a catalyst for the electroless plating. The photoreactive polymer nanosheet was used to increase the adhesion force between the copper layer and polyimide. Furthermore, the cationic polymer nanosheets were used to adsorb a gold catalyst for electroless copper plating. Applying the technique, electroless plated copper was attached strongly onto polyimide film. Micrometer copper lines were fabricated by photopatterning the polymer nanosheets. The process using polymer nanosheets as an adhesive required no surface modification of polyimide substrate and enabled microscale copper line fabrication without discharging harmful waste. Consequently, the technique is useful for next-generation flexible printed board fabrication.