There is a need for some automotive applications to print networks of highly conductive fine tracks onto large flexible substrates. This presentation provides an insight into the mechanisms of ink transfer that determine the quality of the printed features. Printed tracks of sub 25µm width have been demonstrated using high resolution metallic meshes. The ability to achieve high resolution features by screen printing is determined by the interactions between ink rheology, mesh, screen emulsion and printing conditions. Investigation using advanced rheological techniques to study printability provide a rigorous basis for better prediction, control and consistency.
Conductive inks have been characterised by a combination of rheological measures, including constant shear, Small Amplitude Oscillatory Shear (SAOS) and Controlled Stress Parallel Superposition (CSPS). The solid loading has been varied to establish the relationships between rheology, mesh size, print process parameters and printability. This has been backed up by studies using a fine line screen printing simulation rig which has enabled the engagement and separate during the print stroke to be studied using high speed photography.