This research proposes a novel approach to printed electronics manufacturing via molten metal droplet jetting (MMJ). Large scale experimental work is presented to establish suitable jetting parameters for fabrication of high quality conductive electronic traces. Following process optimization, resistivity values as low as 4.49 µΩ-cm for printed 4043 aluminum alloy traces have achieved. This essentially matches the electrical resistivity of the bulk alloy, and it represents a significant improvement over results obtained with printed nanoparticle ink electronics. Electrical resistivity of printed traces that undergo static and cyclical flexing is included in the analysis. The cross-sectional area of traces printed with this approach is orders of magnitude larger than those achieved with nanoparticle inks, hence the traces essentially behave like solid-core metal wire capable of carrying very high currents. The relationship between jetting parameters and the equivalent wire gauge of the uniform printed traces is presented. Early experimental trials revealed the formation of large pinholes inside droplets deposited onto room temperature polyimide substrates. This was hypothesized to be due to the release of adsorbed moisture from the polyimide into the solidifying droplet. Subsequent experiments revealed that heating the polyimide substrate drives off the moisture and eliminates moisture-induced porosity. A multi-physics Ansys process model is also presented to understand behavior of molten metal droplets as they impinge upon a temperature sensitive polymer substrate, spread out, cool down, and solidify. The process model allows the study of many process conditions without expensive and time-consuming physical experimentation.

Library of Congress Subject Headings

Printed electronics--Materials; Manufacturing processes; Liquid metals--Mechanical properties

Publication Date


Document Type


Student Type


Degree Name

Mechanical and Industrial Engineering (Ph.D)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Denis R. Cormier

Advisor/Committee Member

Marcos Esterman

Advisor/Committee Member

Rui Li


RIT – Main Campus

Plan Codes