Electrohydrodynamic printing of high aspect ratio conductive structures

High-resolution electrical connections are a key element of the electronics industry, enabling further miniaturization of integrated circuit footprints and ultimately increasing the integration density. The manufacturing processes of electronic devices have a significant impact on the environment coming from the quantitative use of deposited materials, water, etching chemicals, process energy, and a high number of individual process steps, especially subtractive processes. Additive manufacturing enables the fabrication of electronics in a more resource-saving, environmentally friendly, and design-flexible manner, as the materials are selectively deposited, reducing material consumption and eliminating subtractive/etching processes. This work demonstrates the fabrication of electrically conductive lines with a resolution of less than 10 μm utilizing a maskless and contactless additive technology based on electrohydrodynamic (EHD) printing. Special focus is placed on producing high aspect ratio structures, essential for increasing the conductivity of printed interconnections at such small line widths. It is further shown how the variation of the electric field between the print head and the substrate can be utilized to print three-dimensional structures. This approach enables the additive manufacturing of lines with a diameter of 2.7 ± 0.16 μm and electrical resistance down to 9.2 ± 0.25 Ω per millimeter length, paving the way for new opportunities in the fabrication of high-resolution printed electronics.