| Summary: | 碩士 === 逢甲大學 === 材料科學所 === 94 === Plastic materials have been extensively applied to foods package, architectural construction, medical care, home appliance as well as 3C components. It also attracts tremendous amount of studies of the alternative materials to glass substrate in flat panel display device due to lightweight and flexible nature. However the intrinsic high gas and water vapor permeation might cause damage to the electronic device and loss reliability. Organic light-emitting diode (OLED) display panel device as an example, water vapor provides the environment for electrochemical reaction between moisture and cathode of OLED device and cause dark spot formation. The improvement in moisture resistance and hydrophobic character of plastic materials should then be resolved for further applications.
Plasma polymerization is increasingly important these years for material surfaces modification. Because of low temperature deposition and obtaining unique polymer films than conventionally synthesized polymer. The deposited polymer film possess three-dimensional high cross-linking and pinhole-free structure, thus likely for moisture resistant surface modification on plastic materials. The purpose of this study is corelate moisture resistance and microstructure of the deposited carbon-silicon-nitrogen polymer films on Poly ethylene terephthalate (PET) substrate with respect to the coating parameters. As a result to optimize moisture resistance.
Experimental results show that the deposited film present a featureless morphology without any pinhole and void. FTIR spectrum of the deposits confirm the existed Si-C and Si-N-Si bound with the intensity increased as a function of argon gas flow increase. Strongest SiC and Si-N-Si bond appears to the coating deposited at power input of 5W with argon flow rate at 100 sccm, with working pressure at 0.3 Torr for 60 min deposition time. Water contact angle of the deposits falls into 80°~ 100° showing hydrophobic nature regardless coating parameters used. The film adhesion on PET present the highest 0/5B grade in ISO/ASTM standard scratch test. The pencil hardness of the deposits can reach 4H and is increased as a function of films thickness increasing with condition of high power over 5W, it no longer increase as increasing thickness due probably to the plasma damage to the film.
Moisture resistance of the deposits increases as a function of thickness due to an increased diffusion path of gases. Due to pinhole free nature of the deposits, gas permeation is likely to occur by diffusion effect than structure permeation. Within 2 μm film thickness of the deposits in this study, an increased diffusion paths is effectively increased for better barrier performance. An optimized water vapor permeation rate WVPR 3.9 g·m-2·day-1 of the deposits is improved, 5 times lower than bare PET substrate (WVPR 19.7 g·m-2·day-1) when coating parameter of argon gas flow is 100 sccm with working pressure at 0.3 Torr, power input at 5 W with deposition time 150 min.
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