Use of a 6-axis robot and ink piezo-jetting to print conductive paths on 3D objects. Printed circuit geometry, and conductivity predictive model

Abstract

This paper presents an off-line programming approach for the automatic generation of trajectories and the printing program for a 6-axis robot in order to print accurate conductive paths on 3D objects using a silver microparticle solvent-based ink. The aim of this study was to develop a semi-predictive model in order to - Adapt the printing parameters of a 6-axis robot arm and a piezo jetting print head to the printing speed and substrate type. - Print 3D electronic circuits matching the targeted geometry and conductivity. For the jetting printing process, 2D patterns printed on substrates with different roughness and wettability were analysed as a function of the print head translation speed and jetting frequency which were used as base variables to develop correlations in order to predict line width, thickness and conductivity. The model was based on the assumption that the behaviour of a single drop impacting the printing substrate is close to that of a train of drops (i.e. lines). Thus, the diameter of individual drops on a specific substrate was used to account for support properties and jetting conditions. The study also proposes a methodology to tune the circuit morphology by adapting the jetting parameters as a function of the trajectory and the speed of the 6-axis robot. As a representative case study, a 3D circuit was printed on a disposable paper cup obtaining an excellent agreement between measured and predicted conductivity values.