Patterned\nSurface with Controllable Wettability for\nInkjet Printing of Flexible Printed Electronics

Abstract

Appropriate control of substrate\nsurface properties prior to inkjet\nprinting could be employed to improve the printing quality of fine\nresolution structures. In this paper, novel methods to fabricate patterned\nsurfaces with a combination of hydrophilic and hydrophobic properties\nare investigated. The results of inkjet printing of PEDOT/PSS conductive\nink on these modified surfaces are presented. Selective wetting was\nachieved via a two-step hydrophilic–hydrophobic coating of\n3-aminopropyl trimethoxysilane (APTMS) and 3M electronic grade chemical\nrespectively on PET surfaces; this was followed by a selective hydrophilic\ntreatment (either atmospheric O₂/Ar plasma or UV/ozone\nsurface treatment) with the aid of a Nickel stencil. Hydrophobic regions\nwith water contact angle (WCA) of 105° and superhydrophilic regions\nwith WCA <5° can be achieved on a single surface. During inkjet\nprinting of the treated surfaces, PEDOT/PSS ink spread spontaneously\nalong the hydrophilic areas while avoiding the hydrophobic regions.\nFine features smaller than the inkjet droplet size (approximately\n55 μm in diameter) can be successfully printed on the patterned\nsurface with high wettability contrast.