Preparation of Conductive Nanoink Using Pulsed-Wire-Evaporated Copper Nanoparticles for Inkjet Printing

Pulsed-wire evaporation (PWE) was used to synthesize copper nanoparticles having an average diameter of about 100 nm. These were coated with 1-octanethiol (CH3(CH2)(7)SH) under high vacuum (HV) (5.33 x 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 degrees C, well below the 350 degrees C sintering temperature. Complete removal of 1-octanethiol after sintering was confirmed by X-ray photoelectron spectroscopy (XPS). The resistivity of the hydrogen-sintered copper sample was 1.74 x 10(-7) Omega.m. This dry powder fabrication and coating method is an alternative approach to inhibit copper oxidation and form inkjet-printed lines. [doi: 10.2320/matertrans.M2012137]