Flexible copper wires through galvanic replacement of zinc paste: a highly cost-effective technology for wiring flexible printed circuits†
Conventional electronic circuit wiring methods involve subtractive processes such as etching the copper foils, and thus are inefficient and cause serious environmental problems. Printed electronics technology is expected to be more environmentally benign and have lower cost, due to its additive characteristics. In this paper, we present a simple and efficient strategy to fabricate high performance copper metal fine circuits by a galvanic replacement deposition method. Zinc nanoparticles filled epoxy resin paste is printed onto the substrate film as the seed layer; with a subsequent simple galvanic replacement reaction between Zn and Cu2+, we can obtain a conductive Cu layer that can be further thickened by electroplating. The as-prepared circuits show bulk Cu conductivity, excellent flexibility, adhesion strength and pattern resolution. By adjusting the processing parameters, this technology is suitable for various practical applications, such as flexible circuit boards, RFID tags, touch panels, membrane switches, and photovoltaics, making it a promising solution for low-cost and environmentally friendly fabrication for flexible electronic devices.