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Summary:
Rotogravure is commonly used printing process in flexible packaging and is well suited for the microelectronic production method due to its speed and recilience of the image carrier. This study examines the reproduction of the most basic electronic component, namely a line, in terms of its printed width and gap which can be obtained between the lines. The investigation was carried out using the black separation of a conventionally engraved cylinder on a automatic viscosity controlled commercial printing press printing nitro-cellulose resin based graphic inks to 80gsm one side highly coated paper. By studying the process with a reliable commercial graphic ink the process is being examined under current optimised best practice operation and thus its capabilities are not being limited by development materials. This paper examines the effect of press speed, viscosity and line orientation on the printed line thickness and on the printable gap between lines. The lines were capture by CCD based microscopy and analysed using custom software. Line quality was quantified by the average line width, line porosity, line edge definition and number of edge satellites. The viscosity and line orientation had a significant effect on the printed line width with lines printed in the direction of print being the highest quality and less sensitive to changes in viscosity. The minimum printable line whose consistency would potentially offer sufficient continuity through the line was between 100 and 150 ?m, with reducing viscosity improving the rendition of finer lines. All lines were subject to edge variation as a result of the cylinder diamond engraving with higher viscosity lines producing satellite areas of ink which were independent of the main line body. The line width gain was found to vary with the specified line width with lines less than approximately 250 ?m being smaller than that specified and those above approximately 250 ?m increasing in width. The gap between adjacent regions of ink was found to be larger than that specified with reducing viscosity bringing the gap width closer to that specified. The results have implications for the understanding of the wiping action of the doctor blade and the subsequent transfer of ink to the substrate.