AIMCAL Web Coating Conference 2011 October 23-26 Reno, Nevada USA 1 "ITO Film Trend for Touch Panel Applications" Teijin Chemicals Ltd. Haruhiko Itoh
2 Content 1. Structure and Features of TCF 2. Touch Sensor 3. Technologies for ITO Film 3-1 Film Technology 3-2 Wet Coating Technology 3-3 Dry Vacuum Coating Technology 4. Summary
Structure and Features of Transparent Conductive Film Cross-Section View of Substrate 3 Transparent Conductive Thin Film Coatings Plastic Film Indium Tin Oxide, Indium Zinc Oxide (20~120 nm thick) PC, PES, PET, PEN (~100 µm thick) Coatings Hard Coat, Gas Barrier Transparency Electro-conductivity Plastic LCD Touch Panel E-Paper Inorganic EL Film Photo Voltaic Electromagnetic -wave shielding
Touch Sensors 4 - Resistive Touch Sensor - - Projective Capacitive Touch Sensor - Analog Touch Panel Self Capacitance V V X axis ITO Surface resistance requirements Resistive Touch Sensor:200-500 ohm/sq. Capacitive Touch Sensor:<300ohm/sq. Mutual Capacitance Cover Lens OCA ITO Film OCA ITO Film
Technologies for ITO Film 5 Film Technology Wet Coating Technology ITO Film Dry Vacuum Coating Technology
Film Technology 6 Glass & Film Glass Substrate Film Substrate Heavy Thick Fragile Stiff Light Thin Robust Flexible
Film Technology 7 Glass & Film Glass Substrate Heavy Thick Fragile Stiff Optical Isotropic High Transmittance Low Haze PC Film PET Film Light Thin Robust Flexible Optical Isotropic High Transmittance Low Haze
Film Technology 8 Glass & Film PET Film Sensor Rainbow Defect Display Sensor Cover Lens Display Module Polarized Sunglasses Rainbow defect can be observed through polarized sunglasses. When PET film sensor is used.
Reflectance (%) Film Technology Control optical property (Retardation) Circular Polarizer system 9 λ/4 Plate Reflector Polarizer Slow axis 100 90 80 70 60 50 40 30 20 10 0 λ/4 with ITO 380 480 580 680 780 Wave Length (nm) Absorption of Polarizer Mirror Polarizer λ/4 with ITO Mirror Circular Polarizer
Film Technology 10 Control optical property (Retardation) Low reflection touch panel system Low reflection TP PL PC ITO film with λ/4 Circular PL Air Gap PC ITO film with λ/4 Air Gap PL LCD Current F/G TP ITO film Air Gap ITO glass Air Gap PL LCD
Wet Coating Technology Hard Coat Designing for Resistive Type Touch Panel (Anti-Newton Rings) 11 ITO Film (PET) Glass Substrate with ITO Top ITO Film (Flat Layer) Bottom ITO Film (Flat Layer) Film/Glass Type Touch Panel Top ITO Film (ANR Layer) Top ITO Film (Flat Layer) Bottom ITO Film (Flat Layer) Bottom ITO Film (ANR Layer) With particle Without particle
Linearity Variation L-L0 Wet Coating Technology 12 Hard Coat Designing for Resistive Type Touch Panel (Anti-Newton Rings) Durability Test Comparison 2.0% 1.5% Hard Coat With particle ITO damage around particles 1.0% 0.5% 0.0% Hard Coat Without particle 0 100,000 200,000 300,000 400,000 Writing Cycles Durability Test Condition Weight:250gf Pen sliding speed:210mm/sec. Touch panel structure:film/glass 0.10mm No Damage after durability test Durability Property was measured by TCL original method. Test Result does not guarantee the property.
Wet Coating Technology Hard Coat Designing for Resistive Type Touch Panel (Anti-Newton Rings) Finger Tipping Test Comparison 13 Item 5,000 Times 10,000 Times Hard Coat Without Particles Hard Coat With Particles Linearity No Change No Change Input Force No Change No Change Film Surface No Change No Change Linearity No Change Increase Input Force Increase Film Surface Damaged Touch Panel Surface After Finger Tipping Test Hard Coat Without Particles Hard Coat With Particles
R% R% R% R% Wet Coating Technology Optical control layer designing for Capacitive type touch panel Conventional ITO Film 20 25 15 20 10 15 R ITO After Etching Before ITO Etching Hard Coat Layer 5 10 350 450 550 650 750 Before Wave Etching Length (nm) After Etching 5 R ITO R HC PET Film Back Coat Layer R HC 350 400 450 500 550 600 650 700 750 800 Wave Length (nm) 20 25 15 20 10 15 R ITO R HC After Etching Before ITO Etching Optical Control Layer Hard Coat Layer 5 10 350 450 550 650 750 Wave Length (nm) 5 Etching Mark Improved PET Film Before Etching Back Coat Layer After Etching Before Etching After Etching 14 R ITO = R HC 350 400 450 500 550 600 650 700 750 800 Wave Length (nm)
Dry Vacuum Coating Technology (ITO Deposition) Comparison between Amorphous-ITO and Crystallized-ITO 15 Basic Property ITO Phase ITO Thickness Surface Resistance Amorphous-ITO 20nm 262Ω/ Crystal-ITO 20nm 290Ω/ Total Transmittance 89.1% 90.3% Transmittance b* 2.8 1.9 Film Construction ITO (20nm) Under Coat 25um PET Film Crystal-ITO shows a better optical property Higher transmittance Less color compare with Amorphous-ITO.
Dry Vacuum Coating Technology (ITO Deposition) Comparison between Amorphous-ITO and Crystallized-ITO 16 Reliability Test R/R0 1.5 1.4 1.3 1.2 1.1 60 90%RH Amorphous-ITO Crystallized-ITO R/R0 1.5 1.4 1.3 1.2 1.1 80 Dry Amorphous-ITO Crystallized-ITO 1.0 0 100 200 300 400 500 600 1.0 0 100 200 300 400 500 600 Storage Time (hrs.) Storage Time (hrs.) ITO Thickness : 20nm Initial Rs : 450 ohm/sq. Rs measurement Method : 2 point with Ag paste
Linearity Variation L-L0 Dry Vacuum Coating Technology (ITO Deposition) 17 Comparison between Amorphous-ITO and Crystallized-ITO Durability Test 4.0% 3.0% Amorphous-ITO ITO Peeling 2.0% 1.0% 0.10mm 0.0% -1.0% 0 20,000 40,000 60,000 80,000 100,000 Durability Test Condition Weight:250gf Pen sliding speed:210mm/sec. Touch panel structure:film/glass Crystallized-ITO Writing Times (cycles) 0.10mm Durability Property was measured by TCL original method. Test Result does not guarantee the property.
Dry Vacuum Coating Technology (ITO Deposition) Comparison between Amorphous-ITO and Crystallized-ITO 18 Reliability after laminating optical pressure adhesive Sample Construction Glass OCA TCF After Reliability Test Amorphous-ITO Crystal-ITO Color Change No Change Amorphous-ITO was damaged by remaining acid in OCA.
Sensor Size Dry Vacuum Coating Technology (ITO Deposition) Requirements for Capacitive type TP ITO Film Lower Surface Resistance 19 Existing ITO Technology >200 ohm/sq. with 20nm >20in. 17-10in. 10-7in. 6-3in. Lower Surface resistance offers - Operation Margin - Flexibility on Designing - High response speed - Short charge time - Upsizing sensor size 0 100 200 Surface Resistance (Ω/ ) 300
Surface Resistance (ohm/sq.) Surface Resistance (ohm/sq.) Dry Vacuum Coating Technology (ITO Deposition) Requirements for Capacitive type TP ITO Film Lower Surface Resistance (Low Rs) 20 Resistance = ITO Thickness Necessary to reduce resistance without changing ITO thickness T550 (%) 95 90 85 80 ITO Thickness (nm) Transmittance Cost ITO Thickness (nm) ITO for Resistive Type TP 20nm ITO 300-500Ω/ 75 70 0 200 400 600 800 1000 1200 1400 ITO Thickness (A ) ITO for Capacitive Type TP 20nm ITO <150Ω/
Optical Property Dry Vacuum Coating Technology (ITO Deposition) Requirements for Capacitive type TP ITO Film Lower Surface Resistance (Low Rs) 21 Basic Property Low Rs ITO ITO for Resistive TP ITO Thickness Surface Resisitance Total Transmittance 20 nm 20 nm Initial 218 Ω/ 383 Ω/ After Anneal 147 Ω/ 442 Ω/ Initial 87 % 87 % After Anneal 89 % 88 % Film Construction ITO (20nm) Hard Coat 100um PC Film a* b* Initial -1.0-0.5 After Anneal -0.1-0.1 Initial 3.2 4.2 After Anneal 2.3 2.5 Back Coat
Dry Vacuum Coating Technology (ITO Deposition) Requirements for Capacitive type TP ITO Film Lower Surface Resistance (Low Rs) Reliability Test 22 R/R0 2.0 1.8 1.6 1.4 1.2 85 85%RH Cry-ITO for R-Type TP Low Rs Cry-ITO R/R0 1.4 1.3 1.2 1.1 90 Dry Cry-ITO for R-Type TP Low Rs Cry-ITO 1.0 0 250 500 750 1000 Storage Time (hrs.) 1.0 0 250 500 750 1000 Storage Time (hrs.) Reliability test result was different between two crystal ITO. Performance data are not a guaranteed performance.
Reflectance Color Parameter Transmittance Reflectance (%) Reflectance (%) Reflectance (%) Summary Surface Resistance Optical Property Total Transmittance Haze Combining the presented technology Teijin Chemicals succeeded to develop a new ITO film for Capacitive Type touch sensor. HNC Series Initial After Anneal (1) R/R0 228 Ω/ 152 Ω/ 0.66 (1) Anneal condition:140c/60min. After Etch Before Etch 90.6 90.0 0.68 0.6 a* -0.25-0.47 b* 0.92 1.83 x 0.314 0.315 y 0.331 0.333 a* -0.30-0.46 b* -1.07-0.67 x 0.306 0.307 y 0.323 0.326 24 22 20 18 16 24 14 22 12 20 10 18 16 8 Reliability Initial After 500hrs. R/R0 80C Dry 152 Ω/ 155 Ω/ 1.02 60C90%RH 151 Ω/ 154 Ω/ 1.02 Heat Cycle (2) 152 Ω/ 154 Ω/ 1.01-40C 152 Ω/ 155 Ω/ 1.02 Reflectance Spectrum Without OCA laminated Before Etching (2) Heat Cycle:250 cycles 23 14 6 380 430 480 530 580 630 680 730 780 12 With OCA laminated Wave Length (nm) 10 8 Before Before Etching Etching After After Etching Etching 6 380 430 480 530 580 630 680 730 780 Wave Length (nm) After Etching
24 Thank you for your attention. Teijin Chemicals technical solution can make your products LIGHT and THIN If you are interesting If you have any question If you want to know more about Please contact : h.itou@teijinkasei.co.jp
25