Printing of Fine Resolution Patterns through Electrohydrodynamic (EHD) Patterning Technology

Abstract

In electronic industry the manufacturing of conductive patterning is necessary and ineluctable. Traditionally, lithography is widely used for fabrication of conductive patterns. However, lithographic process requires complicated equipment, is time consuming and the area throughput is limited. In order to reduce the material usage, decrease process time and enable large area fabrication, different fabrication technique is needed. Nonlithographic-direct fabrication methodsuch as inkjetand roll-to-roll printing (also known as printed electronics) are predominant examples with reasonable resolution and high throughput compared to lithography techniques.

Conventional inkjet printing techniques including (thermal and piezoelectric print-heads) are being applied in various applications in the field of printed electronics with modest functional resolution with the feature size of 15~30?m (approximate spherical minimum diameter of 15?m). However, in order to reach this resolution the surface to be printed on needs modifications and also these technologies have limitation to produce droplets smaller than the nozzle size. Moreover, these conventional patterning techniques also have limitation on the type of materials to be deposited in terms of the viscosity of the ink. However, the droplet diameter after printing on the substrate is typically two times larger than the ejected droplet diameter on flat surfaces. Electrohydrodynamic patterning is realized by applying strong electric energy at the tip of the nozzle on the meniscusto generate necessary liquid flow jetting and patterning on the substrate. In this work, electrohydrodynamic patterning methods both continuous and drop-on-demand mode areexperimentally investigated in order to generate patterns with fine resolution on various substrates. Moreover, experimental guidelines are discussed in order to achieve the fine resolution using electrohydrodynamic patterning. Patterns are made by using different inks containing Silver and Copper nanoparticles with different concentrations on different kinds of substrates. In order to check the functionality, the patterns are characterized physically as well as electrically. This study will help in paving road for electrohydrodynamic patterning technology for the formation of submicron patterns for printed electronics applications.