Optimized Formulation and Realisation of Conductive Ink Specially Prepared for Flexible Substrate-Based Printed Electronic Circuits

Abstract

Abstract Evolution of printable, flexible and wearable electronics has given scope for Printed Electronic Technology (PET) in the field of electronics manufacturing. The implementation of inkjet printing technology to printable electronic devices, including field-effect transistors, photovoltaics, RFID tags, and displays, has gained greater attention recently. Several researchers propose conductive ink formulations to suit inkjet printing, including conductive polymers, carbon, graphene, organo-metallic compounds, metal precursors, and metal nanoparticles. Metal nanoparticle suspensions based on silver are the most promising candidate for inkjet printing based on PET owing to their lowest resistivity of all metallic elements. The formulation of silver conductive ink for flexible electronic devices and the realisation of an electronic circuit using the formulated ink are reported in this paper. Silver nanoparticles are synthesized via a chemical reduction process to provide a formulation with a homogeneous shape, size, crystal state, and good dispersion. Silver nanoparticles of size 30-50nm were synthesized and combined with binders and capping agents to form conductive ink. The resistance of the conductive ink pattern was measured as 2.06Ω after sintering for 24 hours @ 60ºC. The formulated ink exhibited good electrochemical reliability and electrical conductivity. The proposed economical synthesis and ink formulation technique would serve as a boon to the field of printed electronics. Further, the material properties can be easily tuned by introducing chemical modifiers into the conductive ink tailored to suit the application to enhance its adhesion or durability. Formulated conductive ink was used to realise electronic circuits to showcase the conductivity, stability and adhesion properties.