It is important to improve the adhesive strength between polyimide films and metal in microelectronics packaging, because polyimide films adhere poorly to many materials. To improve the adhesive strength, one must understand the adhesive mechanism between polyimide films and metal. The influence of the chemical state of bonding at the surface and morphology of polyimide thin films on the adhesive strength has been investigated. Experimental results show that : (1) the adhesive strength is affected by the chemical state of bonding at the surface rather than the morphology of polyimide thin films, and (2) the maximum adhesive strength of 30.4 MPa is obtained for polyimide thin films etched in oxygen plasma for 3 min.