Modeling of Rheological Properties of Metal Nanoparticle Conductive Inks for Printed Electronics

Of late, printed electronics continues to experience an increased demand due to enhanced use of flexible electronics, RFID devices, gas sensors, antennas, and intelligent food packaging devices. Due to this demand, the use of inkjet printers and conductive inks, with desirable properties, is on the rise. Conductive nanomaterials, such as metal nanoparticles and nanowires, carbon nanotubes, and graphene, are promising building blocks for synthesizing conductive inks for printed electronics. In order to develop printing devices that are optimized for flexible electronics, numerical studies on the ink flows and the associated rheological properties are crucial. Therefore, it is critical to provide accurate conductive ink properties for reliable numerical results. However, it is difficult to find such data in the literature since conductive inks for printed electronics contain precious metal nanoparticles and they are not only non-Newtonian but expensive. To address this challenge, this paper aims to utilize common viscosity-shear rate models such as the power law model to study rheological properties such as viscosity, shear rate, and shear stress of conductive inks. Notably, conductive inks made from metal nanoparticles such as silver, copper, gold, nickel, and aluminum are considered in this study. The results obtained from this model have been compared with experimental data. To further understand the effects of temperature and viscosity on synthesized ink, the viscosity-temperature relationship of the conductive ink is also modeled using Arrhenius's law and compared with experimental data. The benefits of using this model for performing numerical simulations of desirable rheological properties of conductive inks for printed electronics are discussed.