![]() 19, 20, 21 This limits the understanding of the physical mechanisms of ink transfer which occur during screen printing. It has been a challenge to develop predictive models of the screen-printing process due to limitations in modeling the rheological properties of screen-printing inks. ![]() The fundamental mechanisms behind this process remain poorly understood. 12, 13, 14, 15, 16, 17, 18 Yet, there has only been limited fundamental research to establish the underpinning science of screen printing. 12 However, squeegee pressure, snap-off distance (the distance between the screen and the substrate) and print speed have not demonstrated consistent trends and have been shown to vary with the rheology of the ink. ![]() 9, 10, 11 Parameters such as squeegee hardness, angle, and geometry have also been found to have consistent effects on a range of inks, where softer squeegees at shallow angles were found to produce thicker deposits. 1, 8, 9 The effect of mesh material and geometry was found to be relatively consistent for a range of inks, with finer meshes leading to reduced film thickness but improved definition, which is preferable for fine feature printing. Research has been conducted to identify the effects of various press parameter settings as well as ink formulation on screen-printed carbon inks and pastes to optimize print quality and electrical performance. 7 Deposition quality is an essential component in the performance of these products. These include resistive heaters, 1 electrochemical sensors, 2 printed batteries, 3 perovskite photovoltaics, 4, 5 energy harvesting in the form of printed pyroelectrics, 6 and thermoelectrics. Screen-printed carbon inks and pastes are widely used in the manufacturing of a range of printed electronics applications due to their electrical conductivity and relatively low cost. This could be used as the basis for the development of predictive algorithms, as well as to improve the understanding of how to optimize print quality and performance. This has provided a better understanding of the mechanism by which the ink transfers from the mesh to the substrate and subsequently separates in screen printing. ![]() Analyses of the images were compared with measurements of the ink properties and corroborated with analyses of the prints. The variation in the four stages of ink flow through the screen, described in the theory by Messerschmitt, has been quantified with respect to changes in snap-off distance and squeegee speed. Therefore, high-speed imaging was used in combination with a screen-printing simulation rig that was designed to provide good optical access to study ink deposition during the screen-printing process. Existing theories are contradictory and lack experimental validation. However, despite its extensive use, the mechanism by which the ink is transferred through the mesh and onto the substrate is not fully understood. Screen printing is the most widely used process in the production of printed electronics due to its ability to consistently transfer inks containing a wide range of functional materials onto a range of substrates. ![]()
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