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

Abstract

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> Ω · 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.