A Study of Inkjet Printed Line Morphology Using Volatile Ink with Non-zero Receding Contact Angle for Conductive Trace Fabrication

Inkjet printed lines on a homogeneous solid substrate are studied under the condition that ink evaporation is not negligible and the contact angle exhibits hysteresis with non-zero receding contact angle (NRCA). A new family of line instability is discovered, featured by formation of agglomerations within a line. The agglomeration is explained by a flow that consistently drives a bead on the substrate towards fresh deposited drops due to concentration-induced surface tension gradient. Morphologies of lines printed with multiple layers are also investigated for the purpose of conductive trace fabrication. A non-uniform morphology is observed across a multi-layer line when the line is printed unidirectionally at a low jetting frequency. This non-uniformity is explained by considering interaction between deposited drops and bulk layer. Optimized multiple-pass printing is developed to produce a uniform line morphology while offering excellent printing efficiency and electrical conductivity.