Preparation of conductive nanoink using pulsed-wire-evaporated copper nanoparticles for inkjet printing

Abstract

Pulsed-wire evaporation (PWE) was used to synthesize copper nanoparticles having an average diameter of about 100 nm. These were coated with 1-octanethiol (CH 3(CH 2) 7SH) under high vacuum (HV) (5.33 × 10 -4 Pa) using vapor self-assembled multilayers (SAMs) to prevent oxidation of the nanoparticles. Conductive nanoink made from the coated nanoparticles was printed on glass. The printed patterns were sintered in hydrogen (99.999 vol%) and mixed gas (Ar 95 vol%+H 2 5 vol%) atmospheres; a high copper line density was achieved. Differential scanning calorimetry (DSC) established that the removal temperature of 1-octanethiol was 143°C, well below the 350°C sintering temperature. Complete removal of 1-octanethiol after sintering was confirmed by X-ray photoelectron spectroscopy (XPS). The resistivity of the hydrogensintered copper sample was 1.74 × 10 -7ω·m. This dry powder fabrication and coating method is an alternative approach to inhibit copper oxidation and form inkjet-printed lines. © 2012 The Japan Institute of Metals.