What is Optical Bonding? Which adhesive to use? What are the advantages?

Traditionally, touch sensors or other rigid materials are bonded to the display with adhesive tape that is only applied to the edges. This process is referred to as “air bonding”. This creates a detrimental air gap that weakens the LCD display, distorts imagery in sunlight, traps impurities that shorten the life of the display, and much more. Optical bonding is the process of attaching a glass/plastic/filter substrate or touch panel to an LCD module. Liquid optically clear adhesive (LOCA) is placed between the cover substrate and LCD to completely fill the air gap. The assembly is cured via a UV-light process that fixes the display/substrate together while solidifying the gel, creating an optically brilliant and ruggedized display solution.

• Achieve Clarity and View Ability

Optical bonding eliminates the internal reflection between the LCD and the cover glass or touch screen because the bonding process creates a single index of refraction. Reducing internally reflected light loss increases display contrast and view ability. Improved display contrast enables displays to be more readily seen in bright ambient conditions, without increasing backlight brightness and the associated unwanted higher power and higher operating temperatures.

• Maximum Protection

Optical bonding dramatically increases both physical durability and impact resistance. Unlike traditional, unprotected LCDs, optically bonded displays can have a cover glass that protects the display from rain, dust, snow, hammers, screwdrivers, etc. This not only helps a display withstand the elements but also makes the LCD cover glass vandal-resistant. Adding custom cover glass, touch screens, optical filters, optical coatings, and other enhancements with optical bonding creates a durable and complete rugged solution. Optical bonding is an effective solution for improving resistance to shake and shock environments – a benefit especially useful in harsh military and avionic environments. A rugged display is one that will last and reach full-term life expectancy.

• Dust and Moisture Prevention

Traditional touch screen configurations are only bonded from the sides and leave a massive air gap in the middle that can allow dust, dirt, and moisture to get in and destroy the display from within. The optical adhesive fills the gap between the substrate layer and LCD, preventing contaminants from impacting the display viewability. Water and electronics just simply do not mix and condensation or impurities can render the display unreadable. This advantage is especially important in maritime environments where displays are often exposed to harsh saltwater.

​

• Accurate Touch Experience

For LCDs with touch sensors attached, the touch sensor cover lens thickness influences touch accuracy and can affect usability with both touch pens and bare hands. Air bonded solutions that require high levels of durability typically require thicker cover lenses which can impact touch performance. Optically bonding the touch sensor to the LCD maintains maximum durability with thinner cover lens materials thus maintaining or increasing touch accuracy. When a display has a more accurate touch experience, it can be used more efficiently in fast-paced environments.

• Improved Heat Dissipation

Heat dissipation is a key element in measuring display performance. The heat generated by the operation of the display is dissipated through optical material and is not blocked by insulating air layers. By filling the insulating air gap between the components, heat can be transferred to the outside environment. The improved heat dissipation also increases the LCD display’s solar aging performance. Improved heat dissipation can decrease display solutions thickness because the need for cooling fans or other similar features is eliminated.