ACETITE ADHESIVES
in LCD Applications
Toshiharu Noguchi
Technical Manager
Asec Co., Ltd.
November 30, 2003
Types Of Adhesives in LCD
Application
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Mother Glass Bonding : UV (Temporary)
Main Sealing
: Heat-cure Epoxy → UV
End Sealing
: UV/Visible Light Cure
Terminal Sealing (Reinforcement)
 TAB
: Silicone → UV
 Clip Pin
: UV
 FPC
: UV
Terminal Bonding (ACP): Heat-cure Epoxy → UV
COG/ITO Coating
: Silicone → UV
Adhesives in LCD Application
Major Advantages of UV or
UV/Visible Light Curable Adhesives:

Fast Cure → Reduction of Assembly Time

Solvent Free → Environmental friendly

One Component → Production Efficiency
↓
Total Cost Saving
MOTHER GLASS BONDING - 1
Processes:
1) Apply Main-Sealing Adhesive
2) Apply Mother Glass Bonding Adhesive
3) Align and mate Glasses
4) UV Light Exposure
5) Pressing and Heat curing
Main Sealing
400~1,000mm
Glass Bonding
400~1,000mm
MOTHER GLASS BONDING - 2
Requirements for Adhesive:

Non-Flow Viscosity

Easy Spread in Small Gap

Hot Strength (No movement during Heating)
AS-6954 (20,000mPa-s, Thixo 4)
END SEALING - 1
End Sealing Processes
1) Suck LC into Cell
2) Wipe excess LC around the Charging Port
3) Apply and Suck-In Adhesive
(by Cooling Method or Press Method)
4) UV Light Exposure
END SEALING - 2
Sealing Process Details
COOLING Method
PRESS Method
STEP 1: Filling LC into Cell
STEP 2: WIPING OFF
Excess LC
STEP 3: Applying UV
Adhesive
STEP 4: Cooling Cell down
to 10-15deg.C
STEP 5: Curing by UV
Radiation
STEP 1: Filling LC into Cell
STEP 2: Stacking 20-60 Cells
STEP 3: Pressing
STEP 4: WIPING OFF
Excess LC
STEP 5: Applying UV Adhesive
STEP 6: Releasing Press slightly
STEP 7: Curing by UV Radiation
END SEALING - 3
Main Problems In End Seal:
4)
2)
1) LC Disordering:
Color difference / Contrast
3) 2) Occurrence of Irregular
shapes (“HIKE”) at Neck
Region:
Poor Appearance & LC
Leakage
1)
LC
3) Gaps between End Seal &
Main Seal: LC Leakage
4) Debonding of End Seal:
LC Leakage
END SEALING - 4
Requirements of End Sealant
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Good Compatibility with LC
(Low Extractive Ionic Compounds)
Good Adhesion to substrates (LC wetted)
Low UV Energy Curability (500~1,000mJ/cm2)
(High CTV → Visible Light Curability)
Resistance to Washing agent
Durability
Appropriate Viscosity
AS-1202 (6,000mPa-s)
AS-1010 (10,000mPa-s)
AS-1203 (20,000mPa-s)
TERMINAL SEALING - 1
Application


Clip Pin: TN (Segment Type)
FPC, TAB: STN, TFT
UV Adhesive
ACF
Process
UV Adhesive
1) Dispensing Process:
One-sided or Two-sided
a) Roller Method
b) Syringe Method
2) UV Light Curing Process
ACF
TAB
FPC
Terminal Sealing - 2
Requirements of Terminal Sealant
•
•
•
•
Good Adhesion to Glass, ITO, Sn, PI
Flexibility (Low Stress)
Moisture Resistance
Durability to withstand Thermal Shock &
Thermal Aging
• High Temp. resistance (Pin Clip)
• Cure Depth > 1.0mm (Pin Clip)
• Appropriate Viscosity
AS-2002 (5,000mPa-s)
AS-1057 (9,000mPa-s)
AS-1204 (20,000mPas)
TERMINAL BONDING - 1
Application

FPC to Glass (ITO, Conductive)
Process
1) Apply ACP on ITO Terminal Pattern
2) Put FPC on the ITO Terminals
3) UV Light Exposure with Pressing
Au coated sphere
Cu Pattern
FPC
ACP
ITO Pattern
Glass
TERMINAL BONDING - 2
ACP

UV Adhesive + Conductive Particles

Particles


Au coated Sphere Resin
Diameter: 3 ~ 5μm
Requirements of UV Adhesive

Good Adhesion to Glass, ITO, FPC

Appropriate Flexibility

Appropriate Cure Shrinkage (Pressing Force)

Moisture Resistance and Durability

Appropriate Viscosity
AS-2002 (5,000mPa-s)
COG/ITO OVERCOATING - 1
Processes:
1) Mount IC Chip on Glass (ITO Circuit)
2) Heat-Pressing
3) FPC Bonding with ACF or ACP
4) Apply COG Overcoat Resin over IC and ITO Pattern
5) UV Light Exposure
Overcoat Resin
IC Chip
ACF or ACP
FPC
COG/ITO OVERCOATING - 2
CURRENT PROCESS Bottle Neck
1) Insufficient Moisture Protection capability
with RTV Silicone
2) Low Productivity due to Long Curing Time
with RTV Silicone
UV Curing Adhesives
COG/ITO OVERCOATING - 3
Requirements of COG OVERCOATING RESIN

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Low Water Permeability
Not Corrosive
Low Stress (Low Shrinkage or High Flexibility)
Toughness
Good Wettability (Glass, ITO, PI, Si)
Adequate Low Viscosity (< 1,000mPa-s)
Fast Cure (< 1,000mJ/cm2)
Durability (Thermal Shock, Heat Aging)
AS-2008 (600mPa-s)
Appendix
LIGHT SHIELD RESIN - 1
Application
1) Protect IC of COG from Malfunction by Light
2) Apply the opposite side of Glass IC mounted
3) Current Process: Al or Black Adhesive Tape
Overcoat Resin
ACF or ACP
IC Chip
FPC
Light Shield Tape or Resin
LIGHT SHIELD RESIN - 2
Requirements of LIGHT SHIELD RESIN

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UV/Visible Light Opaque (Black, White or Silver)
Screen Printable (High Productivity)
Good Adhesion to Glass
Adequate Low Viscosity (< 1,000mPa-s)
Fast Cure (< 1,000mJ/cm2)
Durability
EX03-133 (6,000mPa-s)
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