Introduction and Application of Touch Display Module Air Bonding Process

In modern electronic devices, the combination of touchscreens and LCD modules is the core of human-computer interaction. The bonding process

between the two directly determines the product's display effect, thickness, reliability, and cost. Among these, frame air bonding is a fundamental

and widely used bonding technology.

I. Introduction to Frame Air Bonding Technology

Frame Air bonding, also known as U-shaped adhesive bonding, is a non-full lamination technology. Its core process involves using double-sided adhesive

tape (usually foam adhesive or PET optical tape) to form a U-shaped adhesive frame around the edges of the touchscreen (Cover Lens) and LCD,

fixing them together. The touchscreen and LCD are not in complete contact; there is a physical gap, usually filled with air.

II. Structure and Working Principle of Frame Bonding

A typical frame bonding structure, from top to bottom, is as follows:

1. Touchscreen/Cover Glass: The outermost layer of protection and the human-computer interface.

2. Double-sided Adhesive Frame: Located around the edges, providing structural support and adhesive strength.

3. Air Layer: The gap between the touchscreen and LCD. 4. LCD Screen: Responsible for image display.

Its working principle is as follows: When the user touches the cover glass, the sensor detects the command and transmits it to the main board. The main

board then controls the LCD to display the corresponding image. Light emitted from the LCD must pass through the air layer and the touch screen before

reaching the user's eye.

III. Analysis of the Advantages and Disadvantages of Frame-Laminated Technology

Advantages:

1. Low Cost: The process is simple, using low-cost materials, and eliminating the need for expensive vacuum degassing equipment. The overall

manufacturing cost is far lower than that of full lamination technology.

2. Simple Process, High Yield: Fewer production steps and relatively relaxed requirements for environment and equipment result in higher production

efficiency and a higher yield rate.

3. Easy Repair: If either the touch screen or the LCD is damaged, it can be easily separated and replaced, reducing the difficulty and cost of after-sales repair.

4. Good Impact Resistance: The air layer in the middle provides some cushioning, reducing stress transmission and preventing damage to the LCD screen

when subjected to external pressure or impact.

Disadvantages:

1. Poor Display Quality: This is the most significant drawback of frame-mount technology. Due to the air gap, light undergoes multiple reflections and

refractions as it passes through different media (glass-air-glass), resulting in a grayish, less transparent image with low contrast, especially under strong light.

2. Dust Ingress: If the seal is not tight or the frame ages, dust and moisture from the air can enter between the touchscreen and the LCD through the gaps, 

affecting aesthetics and usability, and are difficult to clean.

3. Thicker Structure: To accommodate the air gap and ensure structural strength, a certain gap is usually required, which prevents the overall module thickness

from being minimized, hindering the design of thinner and lighter devices.

4. Touch Experience: Due to the gaps, light refraction may cause a slight visual discrepancy between the touch indicator and the actual image.

IV. Application Areas of Frame-Mount Technology

Despite its shortcomings in display quality, the significant cost advantage of frame-mount technology ensures its continued viability in certain market sectors.

1. Cost-Sensitive Consumer Electronics:

* Low-end and entry-level smartphones: Especially in emerging markets, such as budget phones and feature phones.

* Ordinary tablets and portable DVD players: These devices typically don't require high-quality display; cost is the primary consideration.

* Aftermarket automotive displays: Such as portable navigation systems and aftermarket center console screens.

2. Industrial Control and Automation Equipment:

* Industrial touchscreens, human-machine interfaces, and industrial control panels. These devices prioritize stability and maintainability in harsh environments;

display quality is not the primary concern. The ease of repair and impact resistance of framed components make them ideal.

3. Home Appliances and Smart Home Devices:

* Control panels for smart refrigerators, washing machine control screens, and air conditioner remote controls. These products typically have small display

interfaces, and high-quality display is not a primary concern; cost control is crucial.

4. Other Specific Fields:

* Public information kiosks, some educational equipment, and low-end POS machines.

In summary 

frame-mount technology, as a classic bonding technique, has secured its market position in competition with full lamination technology due to

its advantages of low cost, high yield, and ease of repair. While it cannot meet the demands of the high-end market for ultimate display effects and ultra-thin

designs, frame-mount remains an economical, reliable, and practical solution in a wide range of applications where price is sensitive, durability and

maintainability are emphasized. In the future, with the continuous development of display technology, frame-mount technology will continue to play an

important role in its areas of strength.