OPTICAL BONDING

Material science & integration

Optical Bonding: Enhancing Visual Integrity through Material Science

Sunlight readability test — LOCA bonded display vs non-bonded display comparison

We eliminate the internal air gap between the LCD and cover glass using precision-engineered LOCA technology. By integrating high-performance chemical bonding with automated manufacturing, we deliver displays optimized for sunlight readability and long-term structural stability in demanding industrial environments.

Material excellence

High-Performance Chemical Bonding: Featuring WACKER Silicone LOCA

We exclusively utilize Liquid Optical Clear Adhesive (LOCA) from WACKER Chemie AG (Germany). Unlike standard acrylic resins, WACKER's specialized silicone-based chemistry provides a stable, low-stress bond that maintains peak optical clarity for over a decade. Its superior thermal stability and UV resistance ensure that the display remains free from yellowing, delamination, or bubble formation, even when exposed to extreme temperature fluctuations or direct solar radiation.

WACKER silicone LOCA — high-transmittance, low-shrink industrial optical bonding
Physics of refraction — index-matched LOCA reducing internal reflections

The science

Physics of Refraction: Stabilizing Contrast in High-Ambient Light

Air-bonding creates a refractive index mismatch between glass (n ≈ 1.5) and air (n = 1.0), causing approximately 4% reflection at each interface. This total 8% reflection washes out image contrast. By injecting WACKER LOCA (n ≈ 1.41–1.51), we match the refractive indices to reduce internal reflections to less than 0.2%. This allows the display to maintain deep blacks and sharp color saturation in outdoor or brightly lit industrial settings.

Eight-stage process

High-Performance Optical Bonding: Engineered Process

Eliminating the air gap via our 8-stage sealing and curing process to effectively improve visual performance, impact resistance, and long-term thermal management in demanding environments.

  1. Step 1

    TP/LCM Inspection

    Rigorous input quality control of both LCM and TP. LCM Inspection checks for foreign objects, screen scratches, dead pixels, or color abnormalities under illumination. TP Inspection verifies surface integrity and flex cable condition.

    Step 1 — touchscreen and LCM incoming inspection
  2. Step 2 — LCM sealing dam application
    Step 2

    LCM Sealing Dam

    Precise application of black UV-curable adhesive around the LCD edges. This dam acts as a barrier to contain the injected sealant and prevent leakage.

  3. Step 3

    Remove Excess Adhesive

    Manually removing any adhesive residue from the display bezel to ensure zero contamination for the next sealant injection stage.

    Step 3 — removing excess adhesive from bezel
  4. Step 4 — WACKER sealant injection
    Step 4

    Inject Wacker Sealant

    The high-performance, low-viscosity Wacker (Germany) silicone sealant is injected, ensuring it flows evenly without air traps or bubbles.

  5. Step 5

    Seal Edges with Black Adhesive

    Application of black UV adhesive around the combined glass stack. This provides structural reinforcement and enhanced waterproof sealing.

    Step 5 — black UV edge seal on glass stack
  6. Step 6 — cleaning residual adhesive
    Step 6

    Clean Residual Adhesive

    Comprehensive cleaning of the external screen surfaces using alcohol to eliminate any residue and ensure cosmetic perfection.

  7. Step 7

    Accelerate Curing via Baking

    Exposure to controlled thermal environment (60°C for 50 minutes) to promote rapid, complete, and low-stress solidification of the entire adhesive stack.

    Step 7 — thermal curing of bonded stack
  8. Step 8 — final optical QC
    Step 8

    QC Testing

    Full optical verification of the finished unit. Check for particulates, alignment, surface scratches, dead pixels, or dark spots under varied color background tests.

Performance Validation

Data-driven comparison: standard air bonding versus sealing-dam optical bonding with WACKER LOCA.

Performance metric Standard air bonding Sealing-dam optical bonding
Reflectivity ~4.0% – 8.0% < 0.2%
Sunlight contrast Significant washout Excellent — sharp and legible
Moisture / fogging High risk Physically eliminated
Yellowing resistance Acrylic: poor Silicone: excellent (WACKER)
Structural integrity Standard Enhanced — shock-absorbing stack

Field performance

Practical Reliability

  • Condensation prevention: Eliminating the air gap removes the possibility of internal fogging in humid or fluctuating temperature zones.
  • Shock & vibration resistance: The cured WACKER silicone acts as a shock-absorber, protecting the LCD from mechanical stress and increasing the overall IK impact rating.
  • Thermal dissipation: LOCA provides superior heat conductivity compared to air, allowing heat generated by the LCD to dissipate through the front glass.
Industrial optical bonding — reliability in vibration, humidity, and temperature cycling

By vertical

Sector Applications

Medical and healthcare displays with optical bonding

Medical & Healthcare

Diagnostic-grade clarity with a seamless surface compatible with hospital-grade chemical sterilization.

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Industrial HMI with bonded touch display

Industrial HMI

Stability alongside heavy machinery with high-frequency vibrations and airborne contaminants.

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Outdoor kiosk display with sunlight-readable optical bonding

Outdoor Infrastructure

Superior readability for kiosks and terminals exposed to direct, intense solar radiation.

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Aviation and marine bonded displays

Aviation & Marine

Reliable performance in environments with extreme pressure changes and salt-mist exposure.

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Engineering team supporting custom optical bonding from 5 to 86 inches

Engineering support

Technical Consultation & Customization

From 5" to 86", our engineering team provides end-to-end support for custom touch sensor integration, optical filter lamination, and structural housing design.

Contact our engineers Request technical datasheet