Characterisation of Fine Lines

The printing of functional inks, such as for sensors, conductive tracks and semiconductors, is generally a combination of solids and fine lines. Functional fine lines require a consistent cross sectional area as well as a consistent width and edge profile and an absence of breaks and voids to optimise their properties. This paper describes the development of quality characteristics and tolerances for functional inks. Fourier and statistical techniques were used to obtain quantifiable measurements of the line quality characteristic. These measurable line properties have been correlated with process parameters. Initially 2-D techniques based on image processing were developed for examining the line width, edge profile and breaks. The effect of thresholding was found to be significant effect on the quality of the measurements. To reduce these anomalies, white light interferometry was used to evaluate the line height and cross sectional area. The quality characteristics have been related to performance criteria for reactive inks.