What is optical bonding?

In optical bonding – also known as display bonding – the space between the display and the cover glass is filled with a transparent adhesive. The result: less reflection, greater stability and a more brilliant image. Depending on the application, we use LOCA, OCA or tape bonding processes to achieve the best optical and mechanical performance.

Optical bonding significantly improves display performance: reflections are reduced, contrast and readability are increased, and the display becomes more resistant to dust, moisture and mechanical stress. At the same time, the process involves higher manufacturing costs, which is why choosing the right bonding technology is crucial.

1. Liquid adhesive (LOCA, OCR, gel)

In liquid adhesive processes, the gap between the display and the cover glass is completely filled with a clear adhesive.

• LOCA (Liquid Optically Clear Adhesive) / OCR (Optically Clear Resin): Liquid, UV-curing adhesives that prevent bubbles and even out unevenness.
• Gel bonding: Use of silicone- or acrylic-based gels that are flexible and reduce mechanical stress.

Advantages:

• Excellent optical quality, fewer reflections
• Better contrast and readability, even in sunlight
• Protection against moisture and dust
• High impact and vibration resistance

Disadvantages:

• Higher process costs and expenses
• Reworking defects is time-consuming

👉 Ideal for high-end displays, outdoor devices and harsh operating environments.

2. Adhesive film (OCA)

This involves the use of a transparent film adhesive (OCA = Optically Clear Adhesive), which is laminated evenly.

Advantages:

• Very clear and thin bonding layer
• Clean, fast processing without curing
• Good for flat and frameless designs

Disadvantages:

• Less flexible on uneven surfaces
• Rework difficult to impossible

👉 Ideal for cost-efficient series production and devices with flat displays.

3. Air gap (tape, frame, air gap)

In air gap solutions, the cover glass is only fixed at the edge – either with adhesive tape, adhesive frames or at specific points. Air remains between the display and the glass.

• Tape bonding: Fixation with special double-sided adhesive tape.
• Frame bonding: Bonding only along a frame.
• Air gap bonding: Glass cover without surface connection, fixed only at the edge.

Advantages:

• Very cost-effective
• Quick and easy processing
• No complex process necessary

Disadvantages:

• Visible reflections due to the air gap
• Lower contrast and poorer readability
• Possible ingress of dust and moisture

👉 Suitable for simple applications, indoor devices and price-sensitive markets.

Applications for optical bonding

Our solutions are used wherever displays need to function reliably – even under extreme conditions:

• Industrial and machine controls
• Medical technology
• Kitchen gastro industry
• E-mobility and outdoor devices
• Measurement and testing technology

Optical bonding in practice

Our solutions have proven themselves in a variety of industries – from outdoor applications to professional kitchens.

Practical example: Optical bonding for e-charging stations

Reflection-free HMI displays for outdoor use – clearly legible in sun, rain and temperature fluctuations.
👉 To the project

Practical example: Optical bonding in professional kitchens

Intuitive operation meets robust technology – bonded touch panels for heat-stressed environments.
👉 To the project

Practical example: Optical bonding in electrical laboratories

Brilliant HMI solutions with glass fronts and precise OCA bonding for demanding laboratory applications.
👉 To the project

Conclusion

With the right bonding technology, displays can be optimally adapted to the application environment and budget:

• Liquid adhesive for maximum performance
• Adhesive film for a clear, efficient solution
• Air gap for cost-effective standard applications

We would be happy to advise you on the right solution for your project.