Comparison of Sustainable and Non-Sustainable Ink Process-Performance Interactions for Additively Printed Circuits

The escalating demand for electronic miniaturization has resulted in the accelerated development of flexible hybrid electronics (FHE) for a diverse array of applications. Current additively printed electronics use nano-particle-based inks in volatile organic compound (VOC)-based solvents. Added focus on sustainability has prompted the emergence of biodegradable substrates, water-based inks, and lower-temperature processable materials. This study explores aerosol-jet and gravure offset printing methods to fabricate circuits with water-based inks, biodegradable substrates, and low-temperature interconnects, comparing them to designs using VOC-based inks. Gravure offset printing is used to develop switch mode buck battery charging circuits with aqueous and non-aqueous silver conductible ink, while aerosol-jet printing focuses on differentiator/filter circuits for signal processing. Component attachment for the circuits has been performed using electrically conductive adhesive (ECA) and low-temperature solder (LTS). The charging circuits have been subjected to long-term accelerated life cycling to study the effect on trace resistance and output charging current provided by circuits printed with both inks. Furthermore, the printed circuits were subjected to a repairability study wherein the attached components were manually removed; the component pads then underwent site redressal using relevant conductible material, followed by curing and subsequent testing to compare the repaired performance with that of the pristine circuit.