Enhancement of Adhesion and Antibending Performance of Ag Circuit on Polyimide Fabricated by Heat‐Assisted Direct Ink Writing Method

Abstract

Herein, flexible circuits with enhanced adhesion and antibending resistance are fabricated by heat‐assisted direct ink writing. The experimental parameters are explored under different nozzle sizes, angles, heights, direct writing speeds, and heating temperatures by selecting an appropriate extrusion speed. The solvent evaporation caused by heating temperature enables the metal particles to densify quickly to form a conductive path. This method is suitable for fabricating devices on polyimide (PI) with appropriate direct writing parameters and is simple to operate. A flexible Ag circuit with a resistivity of 4.31 × 10−8 Ω m and good resistance after 20 000 consecutive bending cycles is fabricated with a nozzle size of 32G, a nozzle height of 10 μm, a nozzle angle of 90°, an extrusion speed of 5 μm min−1, a substrate heating temperature of 70 °C, and a direct writing speed of 1 mm s−1. Large‐area complex flexible display LED arrays are fabricated using thermally assisted direct ink writing.