The role of surface oxides and stabilising carboxylic acids of copper nanoparticles during low-temperature sintering

Abstract

This article provides a detailed discussion of 1-hexanoic-acid-stabilised copper nanoparticles with an average diameter of ∼80 nm prepared from cupric oxide micro-powders for low-temperature sintering applications. The obtained fine particles were dispersed in dipropylene glycol using a bead mill to obtain a stable paste containing 50 wt% copper. Sintering experiments at temperatures in the range of 120–250 °C were performed under a nitrogen or 3%H₂–N₂ gas flow. The lowest resistivity, approximately three times that of bulk copper, was obtained at 250 °C. These particles exhibited good conductivity upon sintering under nitrogen only. 1-Hexanoic acid contributed to the acceleration of sintering by removing the Cu₆₄O oxide layer of the particles and activating the surface. The dispersed copper paste and the copper layer after sintering were observed using SEM.