Flexible glass substrates for roll-to-roll manufacturing

Transcription

1 Science & Technology Flexible glass substrates for roll-to-roll manufacturing Corning - S. Garner, G. Merz, J. Tosch, C. Chang, D. Marshall, X. Li, J. Matusick, J. Lin, C. Kuo, S. Lewis, C. Kang ITRI - P. Shih, J. Shih, M. Lu October 25, 2011

2 Outline Flexible glass for electronic devices Device performance on flexible glass Mechanical reliability of flexible glass Stress Strength R2R processing on flexible glass Summary 2

3 Flexible Glass Enables High-Quality Electronics Substrate choice critical for device fabrication & performance Substrate integrates designs, materials, & processes Essential for overall optimization Glass enables improved resolution, registration, performance & lifetime Ultra-slim flexible glass ( 200µm thick) compatible with: Sheet-fed & web conveyance continuous processes High strength cutting Reliable device assembly & packaging Flexible glass barrier Flexible glass substrate 3

4 Glass Enables Device Performance Optimization Flexible glass offers high-quality surface & optical properties 4 Surface Roughness 200 Device applications Display (e-paper, color filter, OLED, LCD) Touch sensor PV Lighting Ra (nm) Ra Rpv A B A B A B Glass PEN Polyimide Rpv (nm) Flexible glass benefits device performance Hermeticity Optical transmission Surface roughness Transmission (%) Glass Optical Transmission PEN Polyimide Wavelength (nm) 4

5 Glass Enables Fabrication Process Optimization Flexible glass offers thermal & dimensional stability for R2R Continuous processes Patterning & printing Etching Coating, lamination & deposition Flexible glass benefits device fabrication Thermal capability Dimensional stability Flexible glass enables R2R registration Glass strain <10 µm / 100 mm PEN strain 10 s µm / 100 mm Stress (MPa) Stress (MPa) Thermal & Dimensional Stability Glass 25 C & 150 C PEN 25 C 150 C Strain (%) Polyimide 25 C 150 C Web Strain Gage Measurement Flexible glass PEN Strain (%) 5

6 Glass Surface & Bulk Properties Enable Performance Flexible glass device capability demonstrated in <170µm LCD Twisted nematic LCD qvga (320 x RGB x 240) 4 diagonal (80mm x 60mm) Pixel size 83µm x 250µm Aperture 52% a-si:h active matrix backplane TFT channel L=10µm, W=50µm Polymeric substrates not compatible 300 C backplane fabrication 210 C frontplane fabrication 75µm thick, 10cm x 12cm flexible glass LC cell <170µm S. Hoehla, et al., Full Color AM-LCDs on Flexible Glass Substrates, IDW 2010, p

7 Glass Flexibility Enables Conformal Devices Flexible glass device capability demonstrated in <270µm EPD Electrophoretic display 170dpi (640 x 480 pixels) 4.7 diagonal Pixel size 150µm x 150µm Aperture 40% Active Matrix Display Segmented Display Org. TFT active matrix backplane TFT channel L=10µm, W=100µm Driver IC bonding at 180 C 100µm thick, 16cm x 16cm flexible glass Total display thickness <270µm P-Y. Lo, et al., Flexible Glass Substrates for Organic TFT Active Matrix Electrophoretic Displays, SID Display Week, May 18,

8 Flexible Glass Compatible with Large Area Electronics Flexible glass device capability demonstrated in <210µm ChLCD 5 inch color, 80ppi 10.4 inch monochrome, 120ppi ITO post annealed at 220 C Sheet resistance: <25 Ω/ 100µm thick, 25cm x 37cm flexible glass Substrate bonded to processing carrier Total display thickness <210µm K-W. Wu, et al., Color ChLC E-paper Display with 100mm Flexible Glass Substrates, SID Display Week, May 18,

9 Mechanical Reliability of Flexible Glass Substrate solutions optimized for continuous processing Mechanical reliability of glass understood Failure due to distributions of defects & applied stresses Bend strength independent of thickness Mechanical reliability requires controlling defects & applied stress Providing high-strength glass forming, including surfaces & edges Protecting substrate from damage Managing stresses during conveyance, handling & application Bend Stress (MPa) µm 100µm 500µm Bend Radius (cm) Failure Probability (%) µm 100µm Bend Radius (cm) ~10mm

10 Roller Systems Efficiently Convey Flexible Glass Glass web stress managed during device fabrication Flexible glass stiffness similar to other web materials Stiffness ~ E * (thickness) 3 Control stresses through roller handling systems Approach is compatible with sheet-fed or roll-to-roll systems 25 Stiffness (a.u.) Glass Aluminum Paper Polymer Thickness (um) 10

11 Glass After Forming is Inherently Strong Managing defect size & distribution enables reliability Crack systems form when flaw size & stress reach threshold Bend strengths >6GPa measured after forming Subsequent handling & environment can reduce strength ~100x Glass strength depends on glass history Quality of surfaces & edges critical 9 9 Edge quality affects bend strength F a i l u r e P r o b a b i l i t y ( % ) Surface quality affects bend strength Surface damage Crack systems B e n d S t r e s s ( M P a )

12 Coatings Prevent Defects during Device Manufacturing Edge tabs enable device fabrication directly on glass surface Minimizing contact damage enhances reliability Packaging, shipping Device manufacturing In-service use Flexible Glass Web Cross-Section Hermetically encapsulated device Flexible glass Edge tab Optimize solution for specific scenario Edge tabs protect glass during conveyance, winding & device fabrication Flexible glass substrates Flexible glass web Devices fabricated directly on high-quality, hermetic glass surface Laser cut devices from glass web 12

13 Flexible Glass Reliability Enables Device Fabrication Reliability based on managing stress & defect distributions Flexible Glass Mechanical Reliability Flexible Glass Roller Conveyance Web CAMM 13

14 Flexible Glass is Compatible with R2R Processing Demonstrated continuous ITO patterning ITO Deposition Slot Die Coating Exposure Development & Etch Supply Roll Take-Up Roll Cooling Drum Supply Roll Take-Up Roll 10µm ITO lines 30 Ω/ resistivity S. Garner, et al., Flexible glass substrates for continuous manufacturing, Flexible Electronics and Displays Conference, February 9, µm 14

15 Web Conveyance Testing Flexible glass wound 10 inch width onto 6 inch core ID >180 wrap Flexible glass web with edge tab 15

16 Screen Printing Demonstration Compatibility of flexible glass web with edge tab shown Step & repeat screen printing process Engage vacuum stage Screen print Ag ink Release vacuum Advance web Thermal 130 C (switch to UV cure) Compatibility with vacuum stage processing shown Initial results: 150µm width, 14µm height 16

17 Summary Flexible glass offers advantages for device designs, materials & processes Includes optical, dimensional & thermal stability, and hermeticity Enables high-performance active devices Mechanical reliability of glass understood Form with high initial strength & minimize defect creation Manage stresses with appropriate handling & conveyance Optimized solutions are application specific Flexible glass is compatible with sheet & continuous processing Demonstrated asi TFT LCD, organic TFT EPD, direct addressed ChLCD Demonstrated initial R2R process compatibility The authors would like to acknowledge the financial support of the Ministry of Economic Affairs (MOEA) of the Republic of China via the contract No. A351A

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