• Title/Summary/Keyword: polyimide(PI)

Search Result 368, Processing Time 0.031 seconds

A Study on Alignment of Nematic Liquid Crystal by Using Slanted Non-polarized Ultraviolet Light Irradiation on Polyimide Film (폴리이미드막표면위에 경사진 자외선 조사를 이용한 네마틱 액정의 배향에 관한 연구)

  • 서대식;황율연;이보호
    • Electrical & Electronic Materials
    • /
    • v.10 no.5
    • /
    • pp.461-466
    • /
    • 1997
  • In this paper, we developed the new non-rubbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) light irradiation on polyimide (PI) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV light irradiation on PI surface. We successfully obtained that the pretilt angle of NLC is generated about 3.3 degree in the cell with slanted non-polarized UV light irradiation with 70 degree on PI surface, for the first time. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecular and the PI, which is broken the polymer by slanted non-polarized UV irradiation. Therefore, we concluded that the uniform LC alignment is attributed to anisotropic dispersion force due to photo depolymerization with slanted non-polarized UV light irradiation on PI surface.

  • PDF

Response Characteristics of Fast TN Cell on a Polyimide Surface (폴리이미드 표면에서의 고속 TN 셀의 응답 특성)

  • Jeon, Yong-Je;Hwang, Jeong-Yeon;Jeong, Youn-Hak;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2002.11a
    • /
    • pp.514-517
    • /
    • 2002
  • We investigated response characteristics of twisted nematic (TN) cell with different nematic liquid crystals (NLCs) and cell gap d on a rubbed polyimide (PI) surface. High transmittance and fast response time of the TN cell on the rubbed PI surface were achieved by using high birefringence (${\Delta}n$) and low cell gap d. The response time of TN cell on the rubbed PI surface was measured 5.1 ms. The transmittance and response time of the TN cell on the rubbed PI surface decreased with decreasing ${\Delta}nd$.

  • PDF

Effects of Surface Order Parameter on Polar Anchoring Energy in NLC on Weakly Rubbed Polyimide Surface

  • Seo, Dae-Shik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.11 no.12
    • /
    • pp.1128-1132
    • /
    • 1998
  • We have investigated the relationship between the polar anchoring energy and the surface order parameter in nematic liquid crystal (NLC), 4-n-pentyl-4-cyanobiphenyl (5CB), on the two kinds of the weakly rubbed polyimide (PI) surfaces. The observed polar anchoring energy of 5CB is approximately 2${\times}10^{-4}(J/m^2$) and then increases with increasing the rubbing strength (RS) on weakly rubbed surface (RS=57mm) with side chain at $30^{\circ}C$; same results are obtained on weakly rubbed PI surface without side chain. The surface order parameter of 5CB on rubbed PI surfaces increases with increasing the RS at a weak rubbing region. The surface order parameter of 5CB is strongly related to the characteristics of PI material. Consequently, we suggest that the polar anchoring energy of NLC is strongly attributed to the surface order parameter on rubbed PI surfaces.

  • PDF

Relationship between the pretilt angle generation and the polarization component with oblique polarized UV light irradiation on polyimide surface. (폴링미드표면에 편광된 UV광을 경사조사시의 프리틸트각의 발생과 편광성분의 상호관계)

  • 서대식;박두석
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.12 no.1
    • /
    • pp.75-80
    • /
    • 1999
  • In this study, we have investigated the relationship between the generation of pretilt angle and the polarization component in cells with UV light irradiation on polyimide (PI) surface. It was found that the generated pretilt angle is about $1.4^{\circ}$ with S-polarized UV light irradiation of $75^{\circ}$ on PI surface; it may be attributed to the asymmetry triangular of polymer surface with oblique S-polarized UV light irradiation on PI surface. Also, we measured that the generated pretilt angle is about $2.0^{\circ}$ with oblique P polarized UV light irradiation of $75^{\circ}$ on PI surface. Consequently, we suggest that the generated pretilt angle of the NLC is attributed to the interaction between the LC molecules and the polymer surface with oblique polarized UV light irradiation on PI surface.

  • PDF

Effects of Film Stack Structure and Peeling Rate on the Peel Strength of Screen-printed Ag/Polyimide (박막 적층 구조 및 필링 속도가 스크린 프린팅 Ag/Polyimide 사이의 필 강도에 미치는 영향)

  • Lee, Hyeonchul;Bae, Byeong-Hyun;Son, Kirak;Kim, Gahui;Park, Young-Bae
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.29 no.2
    • /
    • pp.59-64
    • /
    • 2022
  • Effects of film stack structure and peeling rate on the peel strength of screen-printed (SP) Ag/polyimide (PI) systems were investigated by a 90° peel test. When PI film was peeled at PI/SP-Ag and PI/SP-Ag/electroplated (EP) Cu structures, the peel strength was nearly constant regardless of the peeling rate. When EP Cu was peeled at EP Cu/SP-Ag/PI structure, the peel strength continuously increased as peeling rate increased. Considering uniaxial tensile test results of EP Cu/SP-Ag film with respect to loading rate, the increase of 90° plastic bending energy and peel strength was attributed to increased flow stress and toughness. On the other hand, viscoelastic PI film showed little variation of flow stress and toughness with respect to loading rate, which was assumed to result in nearly constant 90° plastic bending energy and peel strength.

Synthesis and Characterization of Polyimide Films for Flexible Display Substrates

  • Vu, Quang Hung;Kim, Jin-Woo;Park, Lee-Soon
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.633-636
    • /
    • 2008
  • A series novel films of polyimide (PI) and co-polyimide (Co-PI) containing fluorine with colorless, flexible properties was prepared by a two-step process from various commercial aromatic monomers such as 4,4'-(Hexafluoro iso propylidene) diphthalic anhydride (6FDA), 2,2'-Bis(Trifluoromethyl) benzidine (TFDB), 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (AH6FP) and Bis(4-(3-aminophenoxy)phenyl)sulfone (BAS). Furthermore, these obtained transparent and flexible Co-PI films exhibited excellent thermal stability with the decomposition temperature (at 5% weight loss) around of $500^{\circ}C$ and the glass transition temperature ($T_g$) in the range of $275-350^{\circ}C$.

  • PDF

Precise Measurement of Optical Anisotropy of Rubbed Polyimide on Patterned Glass and its Nanoscale Variation (패턴이 있는 유리기층 위 러빙된 Polyimide의 광학 이방성 미세변화 정밀 측정)

  • Kim, Ha-Rang;Kim, Sang-Youl
    • Korean Journal of Optics and Photonics
    • /
    • v.20 no.5
    • /
    • pp.281-287
    • /
    • 2009
  • The optical anisotropy of rubbed PI(polyimide) film on patterned LCD glass substrate is analyzed using polarimetry. The direction of the optic axis and the magnitude of the very small retardation ($\sim$ 0.4 nm or less) is precisely measured by using a transmission ellipsometer. The variation of the optical anisotropy is presented as the curve of the optic axis versus the magnitude of the phase retardation and it is explained by using a simple optical model.

Preparation and Characterization of Vapor-Grown Carbon Nanofibers-Reinforced Polyimide Composites by in-situ Polymerization (In-situ 중합법에 의한 기상성장 탄소나노섬유/폴리이미드 복합재료의 제조 및 물성)

  • Park, Soo-Jin;Lee, Eun-Jung;Lee, Jae-Rock;Won, Ho-Youn;Moon, Doo-Kyung
    • Polymer(Korea)
    • /
    • v.31 no.2
    • /
    • pp.117-122
    • /
    • 2007
  • In this work, the mechanical and electrical properties, and thermal stability of vapor-grown carbon nanofibers/polyimide (VGCNFs/PI) composite film synthesized by in-situ polymerization were investigated in terms of tensile properties, volume resistivity and thermogravimetric analysis (TGA), respectively. From the results, the addition of VGCNFs with a certain amount into polyimide led to obvious improvement in tensile strength. The volume resistivity of the films was decreased with increasing the VGCNFs content and the electrical percolation threshold appeared between 1 and 3 wt% of VGCNFs content, which was probably caused by the formation of interconnective structures among the VGCNFs in a composite system. The thermal stability of the film was higher than that of pure PI one. This result indicated that the crosslinking of VGCNFs/PI Composites was enhanced by well-distribution of YGCNFs in PI resin, resulting in the increase of the thermal stability of the resulting composites.

Continuous Pretilt Control Using Heterogeneous Polyimide Mixture

  • Kim, Young-Ki;Gwag, Jin-Seog;Jo, Soo-In;Kim, Jae-Hoon
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2008.10a
    • /
    • pp.1584-1587
    • /
    • 2008
  • We proposed a technique controlling continuously pretilt angle in full range with high process margin. The proposed method is characterized by tuning thickness of heterogeneous polyimide (PI) layer that homeotropic PI is mixed with planar PIs.

  • PDF

Polyimide Surface Modification using UV Laser (UV 레이저를 이용한 폴리이미드 표면 개질에 관한 연구)

  • Oh, Jae-Yong;Lee, Jung-Han;Park, Duk-Su;Shin, Bo-Sung
    • Laser Solutions
    • /
    • v.13 no.3
    • /
    • pp.13-18
    • /
    • 2010
  • In this paper, polyimide (PI) surface was modified by UV Laser with a low laser fluence and investigated changes of surface geometry and chemical characteristics by SEM (scanning electron microscope), X-ray diffraction (XRD), XPS (x-ray photoelectron spectroscopy) and the measurements of contact angle of water. PI surface was peeled off and modified with microstructure fabrications by photochemical ablation over the laser fluence of 50 mJ/cm2. As laser fluence increased, delamination of PI surface was occurred largely and strongly. In chemical characteristics, the O/C and N/C atomic ratios increased and contact angle decreased from $80^{\circ}$ to $40^{\circ}$.

  • PDF