EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The demand for miniaturization of electronics and geometrical footprint reduction stresses the need for novel manufacturing processes and materials. Laser-Induced Forward Transfer (LIFT) of nanoparticle-based conductive inks answers to this demand by increasing the printing speed and quality, as well as by enhancing the resolution and electrical properties in the printed raster. Ink formulations with high particle concentrations and viscosities have been proven compatible with LIFT’s processing parameters. Although LIFT is tolerant of large particle sizes, small particles and uniform size distributions facilitate the formation of dense printed patterns, leading to higher conductivities. Solvents with high boiling points that ensure their smooth evaporation during printing are preferred. Although copper nanoparticle-based inks appear to be promising candidates against expensive noble metal nanoinks due to copper’s excellent electrical properties, they are easily oxidized. Oxidation can be avoided by using copper compound or precursor nanoparticles instead of metallic copper nanoparticles. This work focuses on the preparation of superconcentrated copper oxide (CuO) nanoinks from commercial CuO nanoparticle suspensions. The use of different solvents and the rheological properties of the suspensions prepared were examined. The evaporation rate of the solvents was studied via Thermogravimetric Analysis. The size of the nanoparticles was observed via Scanning Electron Microscopy and the stability of the nanoparticles was evaluated via UV-Visible Spectroscopy. The inks prepared were stable for the period of a few months. Their concentration varied between 20 and 60 wt.% and their viscosity was greater than 10,000 cP. Particle sizes were uniform and smaller than 100 nm. The properties of the inks prepared were deemed promising for their employment via LIFT.
Acknowledgement: This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: Τ1ΕDΚ-00814).