Process Recipes of Additively Printed Sustainable Silver-Ink Using Aerosol Jet Printing

Abstract

Ongoing research in flexible electronics has led to the development of various conductible inks and technologies for printing on flexible substrates. The demand for light and compact printed electric circuits has been augmented with the advancement of flexible printing technology. Using environmentally friendly solvents and low-impact waste provides a pathway for creating more sustainable solutions. Recent advances in material development have led to the development of water-based conductive inks for the aerosol-jet platform. In this paper, a Silver Nanoparticle water-based sustainable ink having low viscosity has been studied, and performance has been compared with volatile solvent-based inks. This paper aims to find the process recipe for sustainable ink using the aerosol-jet deposition process with performance comparable to that achieved with incumbent inks. The process parameter study includes investigating different printing and sintering parameters for obtaining desirable electrical and mechanical properties of printed traces. The printing parameters include ultrasonic atomizer mass flow control (UAMFC), sheath flow control (SMFC), and stage speed, and the sintering parameters include temperature and time of sintering. Optical microscopy and white light interferometry are used to characterize print quality. A regression model has been built for the line resistance for different printing parameters. The experiment found the optimal printing parameters as 35 SCCM UAMFC, 50 SCCM sheath, and 3.5 mm/s stage speed. Similarly, after considering the effect on both resistivity and SLF, the best sintering condition has been chosen as 275°C, 10 minutes, giving resistivity and SLF of $\mathbf{5.98}\boldsymbol{E}-\mathbf{06}\quad \mathbf{\Omega}. \boldsymbol{cm}$ and SLF 54.92 gF, respectively. The resistivity of sustainable silver ink is found to be 2 times greater than the non-sustainable silver ink and 3.79 times the bulk silver.