Fabrication of Copper Electrode on Flexible Substrate Through Ag + -Based Inkjet Printing and Rapid Electroless Metallization

Thin film electrodes on a flexible substrate have attracted significant interests from the community for developing flexible and wearable electronics. A prompted routine for inkjet printing conductive patterns on a flexible plastic substrate is developed in this study, in which silver ion-based catalytic ink is utilized as a seed layer for electroless copper metallization in room temperature. Through optimization of Ag + ink composition and printing process parameters, the pattern definition and continuity of electroless plated Cu have been improved. The resistivity at the same order of $10^{-6} \,\Omega \,\cdot \text {cm}$ as bulk copper is achieved, and the adhesion has passed a variety of mechanical tests. Comprehensive characterizations of the printed samples at various processing stages are carried out and presented in this paper.