Robust Design of a Particle-Free Silver-Organo-Complex Ink with High Conductivity and Inkjet Stability for Flexible Electronics

Abstract

Currently, silver nanoparticle based inkjet ink is commercially available. This type of ink has several serious problems such as a complex synthesis protocol, high cost, high sintering temperatures (~200 0 C), particle aggregation, nozzle clogging, poor shelf life, and jetting instability. For the emerging field of printed electronics, these short comings in conductive inks are barriers for their wide spread use in practical applications. Formulating particle free silver inks has potential to solve these issues, and requires careful design of the silver complexation.The ink complex must meet various requirements, such as in-situ reduction, optimum viscosity, 2 storage and jetting stability, smooth uniform sintered films, excellent adhesion, and high conductivity. This study presents a robust formulation of silver-organo-complex (SOC) ink, where complexing molecules act as reducing agents. The 17 weight percent silver loaded ink was printed and sintered on a wide range of substrates with uniform surface morphology and excellent adhesion. The jetting stability was monitored for 5 months to confirm that the ink was robust and highly stable with consistent jetting performance. Radio frequency inductors which are highly sensitive to metal quality were demonstrated as a proof of concept on flexible PEN substrate. This is a major step towards producing high quality electronic components with a robust inkjet printing process.

3D inkjet printed radio frequency inductors and capacitors

“…[13] The AOC ink provides an impressive 1x10 7 S/m, (20%) of bulk conductivity at only 80 0 C. Along with the high conductivity at low temperature the ink exhibits strong adhesion, long term stability (> 5months in a print head), and robust jetting performance. 3D printed material is tested with scotch tape without any removal of the silver film.…”

Design and Fabrication of a Frequency and Polarization Reconfigurable Microwave Antenna on a Printed Partially Magnetized Ferrite Substrate

“…Custom inks namely, magnetic ink made of iron-oxide nano-particles for substrate printing and a metallic ink made of silver-organo-complex (SOC) for patch antenna printing, have been developed in-house [18]. The magnetic ink is prepared by mixing iron oxide (Fe3O4) nanoparticles in SU-8 epoxy resin.…”

Research Status and Prospects of Particle-Free Silver Conductive Ink

“…Mohammad Vaseem [12] et al used silver acetate as a precursor, and used ethylamine and ethanolamine as complexing agents and sintered at 150°C for 30 minutes results in a silver film having a uniform surface morphology and excellent adhesion, and the ink has high stability. To demonstrate the ink's performance, radio frequency inductance measurements were performed on the printed metal's conductivity, thickness, and roughness sensitivity.…”