Browsing by Author "Lai, Po-Cheng"

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Effects of CF(4) plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
;
Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF(4) plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF(4) plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF(4) plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF(4) plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
Effects of CF4 plasma treatment on the moisture uptake, diffusion, and WVTR of poly(ethylene terephthalate) flexible films
(2011-10-25)
Wang, Chih
;
Lai, Po-Cheng
;
Syu, Shu Hao
;
Leu, Jihperng
;
材料科學與工程學系
We studied the effects of CF4 plasma surface treatment on moisture uptake, diffusion, and the water-vapor-transmission-rate (WVTR) of poly(ethylene terephthalate) (PET) films using a CF4 plasma generated by a radio-frequency (13.56 MHz) reactive ion etcher at 60 W. After CF4 plasma treatment, moisture uptake in PET film was reduced with increasing treatment time due to (1) lower adsorption of water molecules onto the hydrophobic surface, as confirmed by contact angle measurement and XPS analysis, and (2) reduced diffusion coefficient through the denser fluorinated top-layer as detected by XRR. In addition, the WVTR of untreated PET is found to be 2.7 g/m(2)/day, while a significant reduction (84%) of WVTR to 0.43 g/m(2)/day, is achieved for CF4 plasma-treated PET film (60 W. 15 min), which alters the surface hydrophobicity (similar to 107 degrees) and simultaneously builds a denser, fluorinated top-layer (47 nm). The surface fluorinated layer has a diffusivity of to 8.7 x 10(-12) m(2)/s and a WVTR of similar to 1.0 x 10(-4) g/m(2)/day based on a series resistance model. (C) 2011 Elsevier B.V. All rights reserved.
Moisture uptake and dielectric property of methylsilsesquioxane/high-temperature porogen hybrids and porous low-k films
(2011-12-01)
Che, Mu-Lung
;
Teng, Jun-Yuan
;
Lai, Po-Cheng
;
Leu, Jihperng
;
材料科學與工程學系
Two high-temperature pore generators (porogens) have been used to study the effect of porogen structure on moisture uptake and k-value in methylsilsesquioxane/porogen hybrid films and their corresponding porous films in a postintegration porogen removal scheme. Poly(styrene-b-4-vinylpyridine) containing di-block structure and pyridine polar group leads to higher moisture uptake and k-value in the hybrid films as compared to poly(styrene-block-butadiene-block-styrene) with symmetrical structure and nonpolar groups. Moreover, the moisture uptake behavior in both as-prepared hybrid films is in physical sorption mode based on their reversible adsorption-desorption curve measured by quartz crystal microbalance. After porogen removal, the k-values of porous films are favorably not influenced by porogen structures, and their moisture uptake is as low as 1.78 wt% even at 40 vol.% porosity. However, based on the simulation of the modified-Rayleigh model, the porous films are found to possess 0.4 vol.% chemisorbed moisture on the pore surface, resulting in 17-23% deviation from the ideal k-values.