As touchscreen technology becomes increasingly prevalent across industrial, automotive, and medical sectors, the need for durable and high-performance display solutions is more critical than ever. One of the most effective methods to enhance display performance is optical bonding. This advanced process not only improves image clarity and mechanical strength but also ensures reliability in demanding environments.

What is optical bonding?

Optische binding serves to bond the display with the touch panel. This process requires carefully selected glue and unique manufacturing technology (usually protected by patents or business confidentiality). This results in high-quality final products with better optical performance, durability, and further benefits described in the article.

Optical bonding process

Preparation

The process starts with choosing the appropriate type of glue depending on the required display parameters, such as its size, location of the device (indoors or outdoors), and estimated operating temperatures. At this stage, the display, glass, and touch panel must be thoroughly cleaned.

Adhesive injection

This involves precisely applying glue on the entire screen surface. The specific glue recipes are strictly protected, although there three general types of bonding materials: silicones, epoxy resins, polyurethanes (now becoming obsolete due to yellowing over time).

Bonding and treating

This is the crucial step of the entire process because it’s applying the touch panel to the LCD module. Avoiding any gaps and air bubbles is the most important issue here. Then the glue is treated with UV light, as traditional heat treatment would increase the risk of material shrinkage.

SOCA – alternative optical bonding process

What is SOCA bonding?

SOCA (Solid / Silicone Optically Clear Adhesive) involves using a translucent gel that is laminated under high pressure in the form of adhesive sheets. High-quality silicone mixtures are used for this purpose, which then serve as a bonding between the protective glass, the touch panel sensors, and the LCD display.

Optical bonding process with SOCA

The optical bonding process in the SOCA method resembles lamination. It involves laying two-sided gel sheets, tailored to fit the size of display components, which are then vacuum bonded on both sides.

Advantages of SOCA optical bonding

In this technology, UV curing is not necessary, thereby the risk of material yellowing is reduced. Compared to the standard “wet” process describe above, the SOCA method is easier to implement and the adhesive maintains greater flexibility, thereby avoiding the mura effect. Importantly, bonding using SOCA gels is reversible and components can be re-bonded again, which facilitates any repairs and modifications, thus reducing the cost of servicing the device. The SOCA optical bonding technology positively affects the quality of the displayed image.

How optical bonding affects display quality?

Improved Display Quality – Reduced Light Reflections and Enhanced Contrast

The optical bonding method eliminates the air gap between the protective glass, the touch sensor, and the display, significantly improving the quality and readability of the displayed image. It is especially visible in high sunlight environment (e.g., outdoor applications) or strong artificial light (e.g., in illuminated production halls or hospital operating rooms).

The main goal of the optical bonding process is to increase the display contrast ratio by reducing the amount of reflected ambient light.

Reduced Disadvantages of Air Bonding

A basic alternative to optical bonding is air bonding This means that in air bonding there is air gap between layers The result of using air bonding is decreased contrast and readability of display.

In addition where touch function may not work correctly due to lack of proper touch sensitivity (called ghost effect).

Condensation Reduction and Dust Protection

Humidity and contaminants can penetrate gaps between screen layers The space filled with optical adhesive eliminates this problem

Increased Mechanical Durability

Removing air gap with optical adhesive increases physical durability For example meets rules of IK7 standard providing protection against mechanical impacts with energy 2J.

Extended Temperature Range and EMI Filtering

The use of optical bonding means additional enhancements like wider operating temperature range To reduce electromagnetic interference EMI filters can additionally be applied using ITO technology

Optical Bonding – Risks of Incorrect Implementation

Mura Effect

Distortions resulting from material tensions in adhesive can lead to mechanical damage particularly visible when displaying dark content A carefully selected adhesive material and gradual curing process contribute to reducing tensions

Delamination – adhesive shrinkage

Shrinkage due to incorrect curing at too high temperatures can cause delamination Thermal tests carried out have shown absence of this phenomenon at 85°C.

Adhesive Yellowing

Yellowing can occur over time due to UV radiation or exposure to high temperatures To prevent this issue we recommend UV-resistant adhesives considering requirements for end user’s application

Where is optical bonding best used?

Optical bonding gaining popularity in variety of applications where rigorous environmental conditions such as wide temperature range or direct sunlight readability are required.

Applications include:

• Medical electronic devices

• Military equipment

• Industrial machines & HMIs

• Automotive displays like those used in Tesla vehicles

These sectors demand exceptional reliability and visual performance—criteria that make optical bonding an ideal solution.

buy your best touch displays from Kadi Display: contact us for best offering

Kadi weergave offers a comprehensive range of custom TFT-LCD modules integrated with capacitive or resistive touch panels. We specialize in delivering fully bonded solutions using advanced techniques including OCR/OCA for improved durability.

Our factory spans over 5,000 square meters where we independently produce LCM/TP/BONDING modules. Our R&D team develops signal adapter boards as well as structural parts tailored for your needs.

We offer:

• Customized cover glass (LOGO/Color/Shape/Thickness)

• Adjustable backlight brightness

• Interface options: TTL/LVDS/MIPI/EDP/HDMI/Type-C/VGA

• High brightness up to 2500cd/m²

• Full AOI inspection during FOG manufacturing

For instance:
10.1″ TFT LCD Display With Optical Bonding & anti-glare
12.1″ LVDS 1280×800 High Brightness With CTP
7 inch Automotive TFT-LCD with Optical Bonding

Our displays are engineered for excellent color reproduction, wide viewing angles up to 178°, fast response times and superior durability—even under harsh conditions.

Contact our skilled team today for technical consultation or custom quotation. Let us help you build a reliable product powered by cutting-edge visual technologies.