Fabrication of extremely conductive high-aspect silver traces buried in hot-embossed polycarbonate films via the direct gravure doctoring method

Depositing inks on a planar substrate by printing is a facile way to fabricate conductive traces and other complicated functional devices. However, irrespective of the printing methods used, the thickness of the inks has an upper limit due to their fluidic property and subsequent wetting on the substrates. Herein, we present a method for creating high-aspect ratio conductive traces by combining hot-embossing and gravure doctoring techniques. Binary-sized colloidal pastes containing Ag nanoparticles and micrometer-sized spherical Ag powder additives were filled using a doctor blade in the grooves of polycarbonate (PC) films inscribed via hot-embossing to create buried traces. Under optimal mixing conditions in which the minimum resistivity was achieved, voids between the microparticles provided a pathway for the volatile solvents to smoothly escape from the filled ink and minimized thickness reduction during the thermal sintering process. A fabricated trace buried in the PC film with an aspect ratio of around 3:1 and a linewidth of 55 mu m showed extremely low resistance of less than 10 Omega/m. A flexible transparent heater was developed using the reported binary colloidal paste. (C) 2021 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Automated summary

A method for creating high-aspect ratio conductive traces by combining hot-embossing and gravure doctoring techniques has been developed. Voids between microparticles help volatile solvents escape smoothly, minimizing thickness reduction during thermal sintering. The fabricated trace shows extremely low resistance, making it suitable for applications such as flexible transparent heaters.