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The application of three-dimensional profiling to the measurement and characterisation of screen printed fine lines. / Timothy James Barden

Swansea University Author: Timothy James Barden

Abstract

Screen printing is used for printing fine lines in the electronics industry, as the process is able to print a large ink film thickness, enabling a variety of resistances, and it is capable of printing onto inflexible surfaces. The cross-sectional area of printed lines determines the electrical char...

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Published: 2008
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42560
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Abstract: Screen printing is used for printing fine lines in the electronics industry, as the process is able to print a large ink film thickness, enabling a variety of resistances, and it is capable of printing onto inflexible surfaces. The cross-sectional area of printed lines determines the electrical characteristics of the line. Presently, line cross-sectional size is determined by measuring line width, as the shape of a screen printed line is assumed rectangular and line height is assumed known from other screen printing process parameters. However, for fine lines this assumption may not be true. The aims of this project have been to ascertain the effect of screen printing process parameters on line quality and investigate the relationship between line width and cross-sectional area for fine lines. A large experimental programme has been undertaken that investigated the influence of the screen printing process parameters on line width, cross-sectional area, line continuity and cross-sectional shape. The screen printing process parameters investigated were the squeegee parameters, the ink type and the screen. The effect of the orientation of the lines to the print direction has also been investigated. A new measurement system has been developed to extract and evaluate the appropriate information from the printed images and allow full analysis of the results. A new parameter, the rectangular index, was developed specifically to understand the correlation between line width and cross-sectional area for fine lines. The measurement system has been used to analyse the results, investigating repeatability, orientation, line cross-sectional size, line continuity and line cross-sectional shape. The line continuity, line edge quality and ink transfer were linked. Sufficient ink transfer leads to good line edge quality and continuity. The ink type and line width were the only parameters to affect the line cross-sectional shape. A new model has been proposed that related line width and cross-sectional area for fine lines. This would permit the use of 2D image processing for on-line quality assurance as opposed to 3D measurement or functionality testing, both of which are slower and have to be used off-line.
Keywords: Electrical engineering.
College: Faculty of Science and Engineering