Cell Filling in Gravure Printing for Printed Electronics

Abstract

Highly scaled direct gravure is a promising printing technique for printed electronics due to its large throughput, high resolution, and simplicity. Gravure can print features in the single micron range at printing speeds of ∼1 m/s by using an optimized cell geometry and optimized printing conditions. The filling of the cells on the gravure cylinder is a critical process, since the amount of ink in the cells strongly impacts printed feature size and quality. Therefore, an understanding of cell filling is crucial to make highly scaled gravure printed electronics viable. In this work we report a novel experimental setup to investigate the filling process in real time, coupled with numerical simulations to gain insight into the experimental observations. By varying viscosity and filling speed, we ensure that the dimensionless capillary number is a good indicator of filling regime in real gravure printing. In addition, we also examine the effect of cell size on filling as this is important for increasing printing resolution. In the light of experimental and simulation results, we are able to rationalize the dominant failure in the filling process, i.e., air entrapment, which is caused by contact line pinning and interface deformation over the cell opening.

Transfer printing for fabrication of flexible RGB color e‐paper

“…The ordinary gravure printing involves a dimensionless capillary number Ca : where U is the printing speed, σ is the surface tension, and η is the apparent viscosity. According to Cen's report, the gravure filling process strongly depends on the capillary number and capillary number below 0.1 facilitate a complete filling. To ensure a complete filling, the value of Ca is less than 0.1 in our experiment.…”

Recent Progress in the Development of Printed Thin‐Film Transistors and Circuits with High‐Resolution Printing Technology

“…The process of gravure printing can be separated into three parts. First, the cells engraved on the cliché are overfilled with inks (filling); second, excess ink is removed from the surface of the cliché using a doctor blade (wiping); third, the ink remaining in the engraved cells is transferred to the substrate (transfer) ( Figure a) . The ink‐transfer ratio in gravure printing processes is mainly determined by the capillary number C a , which is given by:where η is the apparent viscosity, U is the printing speed, and γ is the surface tension.…”

“…Ink spreads on the substrate to fill in the gaps between individual cells. Reproduced with permission . Copyright 2014, American Chemical Society.…”

MHz‐Range Fully Printed High‐Performance Thin‐Film Transistors by Using High‐Resolution Gravure‐Printed Lines

“…Fortunately, given the aggressive resolution scaling we are able to achieve by gravure printing, fully overlapped structures with channel length smaller than 5 µm make the structure entirely tolerant of misalignment without signifi cantly impacting overlap capacitance and switching performance. [17][18][19] Then, semiconductor and dielectric layers were printed by a sheet-fed direct gravure printer. This fully overlapped top-gate architecture can substantially push the limits of printed organic transistors as shown in Figure 1 a, in which the critical feature size is the source/drain line width and channel length.…”

“…This scaling was achieved by exploiting the substantial understanding of the underlying physics of gravure printing that we have achieved in recent years. [17][18][19] Then, semiconductor and dielectric layers were printed by a sheet-fed direct gravure printer. We formulated a new ink composition to gain uniform dielectric fi lms using gravure printing at a speed of 0.5 m s −1 .…”