Magnetohydrodynamic liquid metal droplet jetting of highly conductive electronic traces

Abstract

Magnetohydrodynamic Jet Printing (MJP) is a novel additive manufacturing technique that offers tremendous promise for the fabrication of highly conductive electronic circuits with excellent adhesion on flexible substrates. MJP is an on-demand droplet jetting process in which the fluid is molten metal rather than a conductive nanoparticle ink. The work reported here examines the influence of drop spacing and jetting frequency on line morphology and electrical resistivity. Furthermore, the equivalent wire gauge of printed lines is estimated as a function of the drop volume and drop spacing. Under optimized jetting conditions, electrical resistivity as low as 3.2 MΩ cm (equivalent to bulk resistivity) has been achieved in aluminum 4043 alloy printed onto flexible polyimide. Little or no substrate cleaning is needed prior to printing, and post processing steps such as drying and curing are eliminated with this technique. The process uses metal wire as the feedstock material, making it significantly less expensive than conventional nanoparticle ink printing techniques.