Optical Bonding

Definition:  Optical Bonding refers to the technology that uses transparent optical glue, liquid OCA glue, OCA glue or SCA glue) to completely bond the touch screen and display screen together seamlessly to form a whole screen. The bonding strength is greatly increased.

Advantages: 

• Good display effect: the air layer between the screens is reduced, light reflection and loss are reduced, the brightness and contrast are improved, and the display image is clearer and brighter.
• All-in-one black effect: The boundary between the display area and the non-display area is not obvious, which is conducive to the overall black effect when the entire module is not lit. 
• Higher brightness: OCA glue fills the gaps, reduces light reflection loss, maintains the cleanliness of both screen, and makes the display effect better. 
• Low interference: The touch screen and display panel are closely integrated to reduce noise interference on touch signals and improve touch fluency.
• Improved durability: Optical bonding is beneficial to the stable performance of the SENSOR, and also improves the shock resistance of the entire module, effectively extending the product life of the entire module in harsh environments. 
• Thinner thickess: The overall thickness is reduced through optical glue bonding, making the device thinner and lighter with narrower borders. 

Disadvantages: 

• Complex process: The production process is complex and requires high technology. 
• High cost: material costs and manufacturing costs are high, and repair costs after damage are also high.

Air Bonding

Definition:  it is also known as Double-tape adhesive bonding, that is, simply sticking the touch screen and the four sides of the display screen with double-sided tape. The middle of the two screens is empty and has air.

Advantages: 

• Low process cost: The process is relatively simple, just use double-sided tape on the four sides of the screen for bonding, and the production cost is low. 
• Low maintenance costs: The touch screen and display screen are separate, and damage to one piece will not affect the use of the other, reducing maintenance costs.

Disadvantages: 

• Poor display effect: there is a gap between the two screens, which is easy to reflect light and dust may enter, and the light from the display screen will be filtered, affecting the visual effect. 
• Easy to get dust in: Because there is a gap in the middle, dust and dirt can easily enter, affecting the screen cleanliness and display effect. 

For different type touch screen,  generally it is air bonding for RTP touch( Resitive touch panel) and LCD screen. Either optical bonding or air bonding for CTP touch(Capative touch panel) and LCD screen.

In summary, choosing Optical bonding or Air bonding mainly depends on the positioning and needs of the product. For devices that pursue the ultimate visual experience and high reliability, full fit is a better choice. For applications that are cost-sensitive or do not require excessive display effects (such as some entry-level equipment or specific industrial equipment), frame stickers are a more cost-effective solution.