Improved Adhesion Strength of Silica Thin Films on Polycarbonate Substrates Without an Interlayer Using Remote Atmospheric-Pressure Chemical Vapor Deposition

Silica thin-film coatings used for surface protection of automotive parts are generally deposited by chemical vapor deposition (CVD). In this study, we investigated substrate pretreatment methods to improve the adhesion between a polycarbonate substrate and a silica thin film during the direct synthesis of a hard silica thin film on a polycarbonate substrate using remote atmospheric-pressure plasma CVD, without the use of an acrylic primer intermediate layer. Two types of substrate surface treatments were used: flame treatment and silicone baking. With flame treatment, the adhesion strength of the thin film was 43.5 mN, representing a 26% improvement compared to the untreated sample. With the silicone baking treatment, the adhesion strength was 42.3 mN, representing an improvement of approximately 22% compared to the untreated sample. Therefore, it is considered that the adhesion between the polycarbonate substrate and the silica thin film can be improved by controlling the state of the substrate surface through pretreatment.