SYNOPSISA novel radio frequency (RF) plasma processing technique, known as plasma induced polymerization (PIP), was used in a multistep plasma process to deposit a thin, uniform layer of viscoelastic material on Upilex-S high-temperature polyimide film in order to enhance adhesion between the film and the resin in carbon fiber interleaf composites using epoxy (Hercules 8551-7A) resin systems. In a three-phase study, the processing parameters of residence time, plasma power, plasma pressure, and monomer gas were varied to investigate adhesion improvement. Depositions were characterized using scanning electron microscopy and X-ray photoelectron spectroscopy (XPS) analysis. Compressive mode I1 strain energy release rate (GII,) was characterized by end-notched flexure testing to rank and predict the best RF process for a thermoplastic film interleaf composite structure using polyimide film. Adhesion was improved by as much as 140% over the adhesive performance of untreated Upilex-S using the epoxy resin system. However, adhesive performance was improved in the relatively low temperature (177OC) processing system, and this plasma deposition may not be stable at the higher processing temperatures needed for processing polyimide matrix systems such as PMR-15.0 1995 John Wiley & Sons, Inc.