Surface characterisation of plasma treated flexible substrates for waveguide-on-flex application

This paper reports the physical and chemical effects of argon, nitrogen and oxygen plasma treatments on the surface properties of flexible circuit materials. Both KaptonHN (TM) and Vecstar (TM) films selected as optical flexible substrates under plasma irradiation were studied by atomic force microscope (AFM), contact angles, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The etch rate enhancement of the polymeric materials is more pronounced in oxygen plasma than in argon or nitrogen plasma. The increases of surface functional groups (-COOH, -CNOH) of plasma-modified polymer films are correlated with the increased presence of polar component in surface free energy. While the plasma treatment on KaptonHN (TM) substrates have been widely discussed in literature, the detailed characterisation of both pristine and different plasma surface modified Vecstar (TM) films is reported and compared for the first time. (C) 2009 Elsevier B.V. All rights reserved.