Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3023 TFT-LCD 용배향재료 최진욱동진쎄미켐
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3024 Contents 1. TFT-LCD의배향재료개론 2. 액정분자배열의종류및처리법 3. 액정분자배향메카니즘 4. 개발제품특성
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3025 TFT-LCD 구조와부품 소재 Alignment Layer 배향재료 폴리이미드, 폴리아미드계의고분자물질로서기판에도포하고, 여러방법으로표면처리하여액정을균일하게배향시키는역할을한다.
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3026 TFT-LCD 제조공정 (Cell 공정 ) 전공정 C/F 형성 TFT 형성 TFT 형성 & C/F 형성 TFT array, IT 전극및칼라필터형성 (a-si, IT, Cr, photoresist, etchant, stripper, Color filter, black matrix, over coat) 후공정 Cleaning 기판의불순물을유기 / 무기용매로세척 Aligning agent Printing 상, 하판에배향재료을균일하게도포하는공정 (Aligning Agent) 3 Rubbing 배향막처리공정 Spacer dispensing & Seal printing 기판간극유지및합착공정 (Spacer, main-sealant) Assembling Scribing & Breaking LC injection & Inspection 기판합착후, 액정주입공정 (Liquid crystal, end-sealant)
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3027 액정분자배열의종류및액정분자배향의처리방법 ( 일반적 ) No 분자배열모식도 적용모드 기판조합 배향처리방법 1 VA 89 ~ 90 Nematic Liquid Crystals & Negative dielectric anisotropy Homeotropic (Vertical) Alignment 액정분자의장축방향이기판면에수직 ( ) 으로배향하도록기판표면처리함. ㅁ수직배향계ㅁ임계표면장력의효과ㅁ낮은건조온도 ε < 0 2 3 IPS < 2 TN 4 ~ 8 Nematic Liquid Crystals & Positive dielectric anisotropy ε > 0 Homogeneous (Parallel) Alignment 액정분자의장축방향이기판면에수평 ( ) 으로배향하도록기판표면처리함. ㅁ평행배향계ㅁ배향분자사슬효과ㅁ안정된선경사각ㅁ좁은시야각 Twisted Alignment 모든액정분자가양쪽의기판면에대하여평행으로배열되어있으나그배열방향이양족기판면에대하여 90도비틀어져있다.
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3028 액정분자배향재료의동향 68 75 82 90 2000 고온처리용 : 변성 Polymide (STN 용 ) ( 과제 ) 고신뢰성 Polyimide Si 2 기타 PVA 등 全방향족계 polyimide ( 저온처리형 : CF의내열성 ) (Segment, Dot 표시TN용 ) 저프로세스 저비용저온처리형 : 지방족 방향족계 polyimide (A/M용) 프리틸트각발현 / 시야각및잔상의개선 신규배향막 (ex) 넌러빙광배향막 제 1 세대 제 2 세대 제 3 세대
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3029 액정분자배향막의요구특성및 PI 선택 R 1 H 2 N R 2 NH 2 + NMP H N H R 1 H N R 2 H n -H 2 Heat N R 1 N R 2 n Dianhydrides Diamines Polyamic acid Polyimide 주배향재료와특성개선용재료를적합한비율로배합하여특성구현. 1. 주배향재료 (Polyamic acid 형 ) 우수한내열성, 내용제성, 내구성, 안정된배향성, 높은투과율발현 2. 특성조절용배향재료 (Soluble PI 형 ) 선경사각조절, 우수한막형성능, 높은전압보전율, 낮은잔류 DC 3. Varnish type 우수한인쇄성 TFT LCD 용배향막의요구특성 저온처리 (CF 의내열성 ) 전압보유율 프리틸트각발현 시야각개선 잔상의개선 가용성폴리이미드비전자공역계 측쇄의도입 저극성 분자설계 포토레지스트용용제에의내성 지방족산 / 방향족아민가용성폴리이미드수지 실용적폴리이미드구조 측쇄형지방족산 / 방향족아민함유 폴리이미드 : 가교기를도입한측쇄형 폴리이미드 폴리이미드 : 지방족산 / 방향족아민 ( 저극성 ) 과고극성폴리아믹산의하이브리드화
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3030 액정분자배향의처리방법 ( 실제공정 ) Polyimide rubbing roll 러빙법 Homogeneous (Parallel) Alignment 장점 : 안정된선경사각단점 : 좁은시야각, 표면 scratch glass light lens polarizer glass 광배향처리 ( 평행배향계, 배향분자쇄의효과 ) 광경화성 PI( 광배향법 ) 장점 : 광반응을통한선택적배향이가능청정한공정제공화소분할에의한광시야각확보 Photopolymer
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3031 액정배향상태 +5V +1V -1V -5V (Nonrubbing) n-state ff-state +5V (rubbing) +1V -1V ff-state -5V n-state Applied waveform(60hz)
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3032 액정분자배향메커니즘 ( 개론 ) 극각 θ 방향을결정하는요소 표면장력의효과 극성의상태관계 (a) γ c < γ Lc (b) γ c > γ Lc 수직배향계 평행배향계 ( 방위부정 ) γ c : 기판의임계표면장력, γ Lc : 액정의표면장력 방위각 Φ 를결정하는요소 표면상태의효과 변형에너지 배향분자사슬의효과 (a) 변형에너지- 大 (b) 변형에너지- 小변형에너지가작은 (b) 의배향을취한다 (director는골에평행 ( 지면에수직 )) 무배향 ( 방위부정 ) 평행배향계 분자간상호작용 (a) 랜덤분자쇄 (b) 배향분자쇄
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3033 액정분자배향메커니즘 ( 표면장력 ) 접촉각 γ S γ L θ γ LS Liquid Surface 표면자유에너지 Alignment materials DT-S50 DV-L20 Surfave Energy (dyn/cm) : γ s 47.64 38.92 Surface Tension(erg/cm 2 ) 52 50 48 46 44 42 40 38 36 34 32 30 28 A B C D 0 10 20 30 40 50 Pretilt Angle(θ)(Alignment Materials) good Alignment Characteristic The Surface Energy Decreased with the Increase of contact Angle. The pretilt angles increased with the Decrease of Surface Energy.
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3034 액정분자배향메커니즘 ( 표면상태효과 ) 열경화성 PI 배향막의표면관찰 (AFM) - 건국대액정연구센터
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3035 액정분자배향메커니즘 ( 배향분자사슬효과 ) 18A 3A 21A 8.6A 18.1A DV-Series Pretilt angle(θ) 70 60 50 40 30 20 10 0 DT-Series 0 2 4 6 8 10 12 14 16 18 20 Side chain length(carbon number) The pretilt angles of polyimide increased with the increase of side chain length. 화학공학의이론과응용제10권제2호 2004년 Pretilt angle 100 90 80 70 60 50 40 30 20 10 0 B P CP CB 0.1 0.2 0.3 0.4 rubbing depth(mm)
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3036 Conclusions of Pretilt angle Thickness of film Thickness Degree of imidiazation θ p Curing temperature(degree of imidiazation) Length of side-chain n Length Pretilt angle ~ 300 300 ~ 350 Increase Decrease Rubbing Strength 350 ~ Increase Rigidity of structure Polarity Monomer structure Pretilt angle Polymer structure Pretilt angle Polymer structure Pretilt angle 화학공학의이론과응용제10권제2호 2004년 Pretilt angle(θ) 100 90 80 70 60 50 40 30 20 10 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Rubbing depth(mm)
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3037 Dongjin Aligning Agents for TFT-LCDs Dongjin is providing display materials ALIMAT " for liquid crystal displays (LCD). 1. Alignment coating materials are used in manufacture of LCD. 2. Both polyimide type (pre-imidized organic-solvent-soluble type) and polyamic acid type are available. 3.Specification 1) Low curing temperature 2) High voltage holding ratio 3) Low image sticking 4) Various grades, which achieve the desired pre-tilt angle 5) All kinds of alignment films are available for various alignment modes, including IPS and vertical alignment
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3038 Spec. Sheet of Dongjin s Product Grade name Type Characteristic Metal Ion content(ppm) Particle( > 0.3 μm )(EA/ml) Water absorption(%) Solid Content(%) Viscosity(cP) Cure-condition ( /min) on H.P. Decomposition temp ( ) in air Film Hardness Reflective Index(589.3 nm ) VHR (%) at 25 (60 ) Residual DC (mv) at 25 Pretilt angle(deg) Pre-curing Main-curing DT Series DV Series TN - Standard VA - LR Excellent Printability High VHR, Low R-DC < 0.5 < 0.5 < 10 < 10 < 1.0 < 1.0 7.0 ± 0.5 7.5 ± 0.5 20 ± 4 20 ± 4 90 ~ 120 / 1 ~ 5 min 200 ~ 230 / 5 ~ 20 min 460 440 4H 3H 1.63 1.60 99 (96) 99 (98) 50 20 4 ~ 8 89 ~ 90
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3039 개발제품의열적특징 T i * R 1 N R 2 N * (1) Polyimide (PI) Polyamic acid (PAA) H H * N Thermal Imidasation Temperature f Poly(amic aicd) H N R 2 R 1 H * Decomposition Temperature of PI Alignment Materials DT-Series DV-Series T d ( o C) 292 286 T 10 ( o C) 527 521 Temperature ( o C ) The curves of TGA (heating rate 5 /min) T d : temperature of weight loss starting point T 10 : weight loss 10 wt% point (T 10 ) Poly(amic acid) 의 thermal Imidazation temperature가 180~383 의범위에서나타낸다. Polyimide의 decomposition temperature가 480 에서 500 이상의높은값을나타낸다.
Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 3040 개발제품의전기광학적특징 V-T Characteristics Voltage Holding Ratio 100 100 DV-Series DT-Series Transmittance (%) 80 60 40 20 DV-Series DT-Series Voltage Holding Ratio (%) 98 96 94 92 0 Cured at 200 o C, LC Mixture MLC-2003 90 0 1 2 3 4 5 20 40 60 80 Applied Voltage (V) Measurement Temperature ( o C) Alignment materials V 10 V 90 Alignment materials VHR (%) 25 VHR (%) 60 DV-Series 1.1 2.1 DT- Series 99.01 96.92 DT-Series 1.2 2.2 DV- Series 99.21 98.06