Study on the web deformation in ink transfer process for R2R printing application

Abstract

Web deformation occurring in the ink transfer process from the printing roller to the flexible web was investigated using a CFD technique for the application in roll-to-roll printed electronics. Analysis for the flow-structure interaction was conducted to assess the deflection and stress distributions of the web. To make the present analysis more relevant to the real printing system, both realistic geometric configuration and ink properties were set up using the information obtained from the typical roll-to-roll system. Fluid properties were found to influence to the shape of the transferred ink and the web deformation. As the line width becomes smaller than 100 microns, the appreciable distortion in the shape of the transferred ink occurred due to a relative importance of surface tension. Non-negligible web deflection occurs in all the cavity geometries considered in the present work but the ratio of the web deflection to the line width gets smaller as the printing pattern width becomes smaller. Thus, the surface and deflection will be important factors for the better printing quality under the 100 micron range.

Active Vibration Control of Moving Web with Varying Density

“…T . Equation (4) can be written as the dynamic equation (6) where M, L, H and D are matrices ((N × N), where N = m n), and M is non singular. Here D is the input matrix, and U is a dimensionless feedback control vector.…”

“…If the vibration is not effectively controlled, it will seriously affect the quality of production [1][2][3][4][5]. Besides, after coating or printing, the density uniformity of the web is changed and the dynamic behavior of the web becomes more complex [6]. Thus, controlling the moving web with varying density effectively to reduce or avoid generating strong vibration is important.…”

A numerical study of the ink transfer process for roll-to-roll printing applications

“…However, a recent study 20 reported that the time for the combined drying and curing processes could be successfully reduced by a factor of as large as 5. Therefore, higher web, handling speeds of up to 30 mpm (¼0.5 m/s) compared to the speeds chosen in previous studies, [17][18][19] was considered in this study. Obviously, a relatively higher speed shortens the convection time-scale, thus increasing the importance of the inertial effect relative to that of viscous action.…”

“…They successfully illustrated the role of surface wettability and cavity size of their model. In more recent studies by Lee and Na 17,18 and Kim and Na, 19 the geometry of gravure printing, which is one of the most popular R2R printing methods, was considered for direct relevance to real applications. Kim and Na 19 showed that the characteristics of the transferred ink strongly depend on the magnitude of the viscosity under the assumption of Newtonian fluid.…”

“…In more recent studies by Lee and Na 17,18 and Kim and Na, 19 the geometry of gravure printing, which is one of the most popular R2R printing methods, was considered for direct relevance to real applications. Kim and Na 19 showed that the characteristics of the transferred ink strongly depend on the magnitude of the viscosity under the assumption of Newtonian fluid. Their result that the characteristics of a printed pattern depend on the magnitude of the viscosity prompts the need for considering variable viscosity since the shear rate and thus, the viscosity show considerable spatial variation in gravure printing applications.…”