Two-Step Flash-Light Sintering of Copper-Based Inkjet-Printed Patterns onto Polymer Substrates Used in Flexible Electronic Devices

Abstract

High-speed flash-light sintering to fabricate inkjet patterns on the flexible substrates employed in lightweight devices is used. A two-step sintering process, i.e., presintering to cause slight necking of copper nanoparticles (CNPs) and final sintering to complete densification, is used to sinter copper-based inkjet patterns. These patterns are more dense and less resistive than those formed via one-step sintering. The specific resistivity of the pattern created using only the second sintering step is 2.65 x 10(-7) omega m and that of the two-step pattern is 0.84 x 10(-7) omega m, and the value shows little change over 180 days. Two-step-sintered patterns on a polyimide substrate exhibit very dense microstructures, surface porosity ˂7%, and no damage. Thus, highly conductive copper-based inkjet patterns on a flexible substrate are successfully fabricated.