In this study, we apply UV/ozone treatment to modify the surface properties of polyimide substrate and investigate the effects of UV/ozone treatment on surface properties of polyimide and the morphologies of ink-jet printed Cu patterns. Wettability of polyimide surface is enhanced by UV/ozone treatment as confirmed by contact angle analysis and XPS results. The change in wettability affected droplet sizes and morphologies of ink-jet-printed lines. The average droplet size increased from 26.8 mu m on untreated polyimide to 42.5 mu m after UV/ozone treatment. Furthermore, irregular patterns of coexisting beads and short lines were observed in untreated polyimide film, despite minimal overlap of dots. In contrast, patterns that were ink-jet printed on polyimide film that was modified by UV/ozone for 1 h showed continuous lines with straight edges. (C) 2011 Elsevier B.V. All rights reserved.