flexible glass substrates for roll-to-roll manufacturing · · 2016-12-21technology flexible...

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 © Corning Incorporated 2011 Science & Technology

Outline

• Flexible glass for electronic devices

• Device performance on flexible glass

• Mechanical reliability of flexible glass – Stress – Strength

• R2R processing on flexible glass

• Summary


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 substrate

Flexible glass barrier


0

20

40

60

80

100

200 400 600 800Wavelength (nm)

Tran

smis

sion

(%)

Glass Enables Device Performance Optimization Flexible glass offers high-quality surface & optical properties

Surface Roughness

Glass PEN Polyimide

0

1

2

3

4

A B A B A B

Ra

(nm

) Ra

0

50

100

150

200

Rpv

(nm

)

Rpv

Optical Transmission Glass

PEN

Polyimide

• Device applications – Display (e-paper, color filter, OLED, LCD) – Touch sensor – PV – Lighting

• Flexible glass benefits device performance

– Hermeticity – Optical transmission – Surface roughness


Glass Enables Fabrication Process Optimization Flexible glass offers thermal & dimensional stability for R2R

Thermal & Dimensional Stability

0

10

20

30

40

50

0 0.5 1 1.5 2 Strain (%)

Stre

ss (M

Pa)

Glass 25°C

PEN 25°C

Polyimide 25°C

& 150°C

150°C

150°C

05

1015202530

0.00 0.05 0.10

Strain (%)

Stre

ss (M

Pa) Flexible glass

PEN

• 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

Web Strain Gage Measurement


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.1689-1692.


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%

• 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, 2011.

Active Matrix Display

Segmented Display


Flexible Glass Compatible with Large Area Electronics Flexible glass device capability demonstrated in <210µm ChLCD

• 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, 2011.

5 inch color, 80ppi 10.4 inch monochrome, 120ppi


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

0

100

200

300

400

500

0 5 10 15 20 25 30Bend Radius (cm)

Ben

d S

tress

(MP

a)

500µm 100µm

50µm

1.000.100.01

90

50

2010

5

21

Bend Radius (cm)

Failu

re P

roba

bility

(%)

0.1 1 Bend Radius (cm)

10

100µm 200µm

~10mm


0

5

10

15

20

25

50 70 90 110 130 150

Thickness (um)

Stif

fnes

s (a

.u.) Glass

Polymer

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

Aluminum

Paper


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

1 0 0 0 5 0 0 2 0 0 1 0 0 5 0 2 0 1 0

9 9

9 0

5 0

2 0

1 0

5

2

1

B e n d S t r e s s ( M P a )

F a i l u

r e P

r o b a

b i l i t

y ( %

)

Edge quality affects bend strength

Surface damage

Crack systems

Surface quality affects bend strength


Flexible glass web Flexible glass substrates

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

• Optimize solution for specific scenario

• Edge tabs protect glass during conveyance,

winding & device fabrication

• Devices fabricated directly on high-quality, hermetic glass surface – Laser cut devices from glass web

Edge tab Flexible glass

Hermetically encapsulated device

Flexible Glass Web Cross-Section


Flexible Glass Reliability Enables Device Fabrication Reliability based on managing stress & defect distributions

Flexible Glass Mechanical Reliability Flexible Glass Roller Conveyance

Web conveyance @ CAMM


Flexible Glass is Compatible with R2R Processing Demonstrated continuous ITO patterning

Cooling Drum

ITO Deposition Slot Die Coating

Supply Roll Take-Up Roll

Exposure

Supply Roll Take-Up Roll

Development & Etch

50µm S. Garner, et al., “Flexible glass substrates for continuous manufacturing”, Flexible Electronics and Displays Conference, February 9, 2011.

10µm ITO lines 30 Ω/ resistivity


Flexible glass web with edge tab

>180° wrap

Web Conveyance Testing Flexible glass – wound 10 inch width onto 6 inch core ID


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 cure @ 130°C (switch to UV cure)

• Compatibility with vacuum stage processing shown – Initial results: 150µm width, 14µm height


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. A351A11100.

flexible glass substrates for roll-to-roll manufacturing · · 2016-12-21technology flexible...

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