In this study, the adhesion and interface characteristics of NiCr/Cu metal film oil PI film modified by O-2 ion beam were investigated. The surface modification of PI film by O-2 ion beam enabled a significant decrease of contact angles of water from 68 degrees to 4.4 degrees at an ion dose of 1 x 10(18) ions/cm(2), which resulted in an increase of surface energy by a factor of two, The XPS (X-ray Photoelectron Spectroscopy) spectrum showed that the functional groups of C-O and C=O bonding oil PI surface were increased by the interaction between scissored unstable chains and reactive ions. The peel strength between PI and NiCr/Cu metal film increased with all increase of ion dose and the highest peel strength of 0.70 N/mm was obtained at an ion dose of 1 x 10(18) ions/cm(2). According to the XPS depth profile from NiCr metal layer into modified PI film, the O1s peak was broadened at near-interface region with an increase of depth from NiCr layer, which indicates that the new chemical bonding state was formed. In addition to C-O and C=O bonding, the newly formed chemical bonding at the interface between NiCr metal film and PI film was identified as metal-oxide compounds such as NiO, Cr2O3, and Cr-O by XPS curve fitting. Consequently, the improvement of adhesion is primarily attributed to the strong chemical bonding caused by the chemical interaction between NiCr and newly formed functional group by O-2 ion beam. (C) 2008 Elsevier B.V. All rights reserved.