PRODUCTS & SERVICES

Bonding Methods

When it comes time to assemble or bond a touch panel or a lens to a display, multiple methods exist:

Full Optical Bond
- LOCA (OCR)
- OCA
Perimeter Tape
Perimeter Adhesive Bond

At DCL, we are experienced to know which method is right for your application

Optical vs. Perimeter Bonding

Bonding methods, or the attachment of a touch panel or lens to a display, is typically done two ways: a perimeter bond or a full optical bond.

Which is best should be based on key objectives such as optical performance requirements, application environment, durability and budget considerations.

DCL offers both methods and more importantly knows when and why to consider either for your application.

Optical Bonding

An optical bond refers to the assembly of a touch sensor or lens to an LCD using an optically clear index matched adhesive to fill the space between the two components.

While there are a number of methods and materials sold as an optical bond, they each have the primary objective of reducing reflections and improving a display solutions visual performance. A number of secondary benefits make this method appealing for many applications.

Let's explore key features, materials and benefits available

Benefits

01/

No matter the material or method, the primary benefit of optical bonding is reduced surface reflection in the display/touch assembly by filling the air gap between the two components with an index matched optically clear material.

02/

Since high ambient light viewability is as much about contrast ratio as it is about brightness, reductions in reflection means less wash out, better extrinsic contrast and improvements in high ambient light viewability of your display solution.

03/

Additional benefits include protection from humidity forming or dust particles collecting between the components

04/

Since the touch sensor or front lens is now optically adhered to the LCD, you gain increased shock resistance – damage in the display and touch solution stack are significantly minimized

Things to know

01/

An optical bond can be costly depending on factors, such as:

Where the process gets done
Material and curing process used
LCD size and quantities to be bonded

02/

There are a number of material choices in the market. Each is not right for all applications

Silicone and urethane materials, anti yellowing and UV resistance and other application specific requirements can make one material more desirable than others

03/

The acronym jumble

LOCA or Liquid Optically Clear Adhesive
OCA or Optically Clear Adhesive
OCR or Optically Clear Resin
These are some of the acronyms used to describe materials in an optical bond

04/

LOCA or OCR materials are typically UV or air cured. Some solutions can utilize an OCA, or thin to medium thickness sheet material, which is often processed in an autoclave to complete the bond process. This is also sometimes referred to as a dry-bond

Optical Bonding has tremendous value and challenges.

Speak to DCL about your application and we will walk you thru options

Perimeter Bonding

A perimeter bond is a method of attaching a touch screen or lens to a display using a double sided adhesive tape, a die cut gasket or machine applied adhesive.

Material choices are typically based on level of adhesion desired, application environment and desired protection from moisture or dust intrusion.

Once a gasket is applied, fixtures or robotic alignment is used to properly align and adhere the touch screen to the display.

Perimeter bonding is a low cost, widely used and accepted assembly method for touch sensors, lens and display integration.

Benefits

01/

Low cost assembly method

02/

Easily reworkable

03/

Provides a good seal against dust and moisture

04/

Multiple approaches

Seamless Die Cut Gasket
L Shaped Gaskets
Strips
UV or Air Cured Adhesive

Things to know

01/

These methods leave an air gap between the two components

Humidity can build up in the gap
There can be additional reflections leading to image wash out depending on LCD optical characteristics

Perimeter Bonding is an effective, low cost assembly method.

Speak to DCL about options that best fit your application.

Contact the DCL team to discuss your application and determine which bonding method is best for your application