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What Is Touch Screen Cover Glass?


What is Touch screen cover glass?

The touch screen cover glass is mainly used in the outermost layer of the touch screen. And the English name is Cover lens. Also known as strengthened optical glass, glass window, strengthened mobile phone lens, etc. The main raw material of the product is ultra-thin flat glass. It is processed by cutting, CNC carving, thinning, strengthening, coating, printing and other processes. It has the functions of impact resistance, scratch resistance, oil stain resistance, fingerprint resistance, and enhanced light transmittance.

Touch Screen Cover Glass Has Become The Mainstream

After attaching a cover glass on the outer surface of the touch screen, it protects the touch screen on the one hand. What’s more, you can print it with different colors, patterns, and markers on the other hand to decorate and beautify the product. Since entering the touch era marked by Apple products. Because capacitive touch screen solutions have the stable performance, good touch and other advantages. It has become the mainstream of human-computer interaction for mobile terminals such as mobile phones, tablets, and touch-sensitive notebooks. Regardless of the touch technology, the cover is an indispensable protective component. And the glass cover has gradually become the mainstream of the cover due to its high light transmittance and strong scratch resistance.

The Application Of Touch Screen Cover Glass

A variety of electronic consumer products with touch and display functions use cover glass widely. Such as capacitive touch screen mobile phones, tablet computers, digital cameras, GPS, various query terminals, various self-service terminals, ATM machines. And on-demand machines , Large-screen touch electronic whiteboard, etc.

The Cover Glass Is The Mainstream Protection Scheme For Various Touch Technologies

The cover glass is the outermost layer of the capacitive touch screen material that plays a protective role. Due to direct contact with the outside world. In addition to the surface finish, thickness and other parameters, the properties of high hardness, compression resistance. And scratch resistance also determine the quality of the cover glass. The cover glass (Cover Glass or Cover Lens) has obvious advantages in these important parameters compared to cover plates of other materials. So it has gradually become the mainstream protection solution for various touch technologies.

Touch Screen Cover Glass Is The Most Important Component

Generally, the touch module is formed by bonding three parts: a cover lens, a sensor, and a liquid crystal panel. At present, capacitive touch screen solutions still coexist with multiple technologies. The two major camps of film and glass share the touch market. However, whether film (GF, GF2) or glass (GG, OGS), or Samsung and Apple dominated On- Cell, In-cell, and glass cover are all important components.

The Main Production Technical Steps And Principles Of Touch Screen Cover Glass

The whole process starts with the cutting of raw materials and ends with coating and packaging of finished products. The specific description is as follows:

1) Cutting

Cutting is a first step in the processing of cover glass. A cutting machine is used to cut the original size of the white sheet glass into a blank slightly larger than the final product size.

2) CNC engraving

CNC engraving glass uses the grinding wheel groove of the engraving machine to grind the rough glass, remove the margin. And then drill holes, engrave grooves and edging through a drill to meet the requirements of the final product.

3) Grinding

The main purpose of grinding is to make the thickness of the glass substrate meet the key process required by the final product. The main working principle is to place the glass in the double-sided flat grinding disc of the grinding machine. And add abrasives for grinding to remove excess thickness. Grinding can make the substrate glass reach the required thickness of the finished product and increase the flatness.

4) Strengthening

The main purpose of strengthening is to increase the surface stress of the glass.So that the glass can achieve the effects of scratch resistance and impact resistance. The main working principle is that the glass is placed in a potassium nitrate solution at 400 degrees Celsius. So that the sodium ions on the glass surface and the potassium ions in the potassium nitrate solution are fully ion exchanged. Because the volume of potassium ions is larger than that of sodium ions, and the potassium ions are squeezed into each other. A stress layer is formed on the glass surface to achieve the effect of glass strengthening.

5) Silk screen printing

The main purpose of screen printing is to make the ink show different colors, different shapes and patterns on the glass surface.  The main working principle is to make the ink adhere to the glass surface through screen printing and drying to achieve the desired appearance of the finished product effect.

6) Coating

The main purpose of coating is to form a film with a specific function on a specific position on the glass surface. The main working principle is that the film is deposited on the glass surface by evaporation, electron gun bombardment or magnetron sputtering in a vacuum state. The current main application films are anti-fingerprint film (AF) and anti-reflection film (AR). Wait.

7) Cleaning

The main purpose of cleaning is to remove dirt and dust spots attached to the surface of the glass by ultrasonic. So that the cover glass can achieve better results in the strengthening, silk screen, coating and other production processes.

Touch Screen Cover glass Process Analysis

The cover glass substrate are including soda-lime glass and high-alumina glass according to different production formulas . There have float method and overflow method according to different production processes. At present, soda lime glass is use the float process. Therefore, there are currently three types of glass cover substrates on the market. Namely float soda lime glass cover substrate, float high alumina glass cover substrate and overflow high alumina glass cover substrate.

From the formulation point of view, the strengthening depth, compressive stress and other parameters of soda lime glass are far inferior to high alumina glass.  From the point of view of the process, the manufacture of high-alumina glass due to the float process has inherent defects. (Due to uneven density, it is easy to warp after strengthening). The product quality is not as good as the overflow method. And the processing yield of the glass cover processing plant in the middle reaches is low. Therefore, in terms of performance, overflow high-alumina glass is the best. And the overflow high-alumina glass cover glass is for high-end market currently.


Overflow High Alumina Cover Glass VS Float High Alumina Cover Glass

The overflow process produces the best products. At present, there are two main manufacturing processes for high-alumina glass cover substrates: float method and overflow method. The float glass process is the oldest glass manufacturing process and is very mature in the manufacture of soda lime flat glass. The difficulty of converting from flat glass to cover glass is how to make the glass thin. However, due to the inherent deficiencies in the process, the float method is not easy to manufacture high-alumina glass cover plates. And the product quality is not as good as the overflow method.

The high-alumina glass contains more alumina and calcium oxide in its formula. Under the same temperature conditions, the surface tension of the glass is large (about 20% larger than ordinary soda lime glass). As a result, high-alumina glass exhibits the characteristics of high viscosity. The float method uses gravity to flatten and cool the molten glass on a horizontal surface. However, high-alumina glass liquid has high viscosity, is affected by surface tension, and has poor lateral fluidity. It is also difficult to use vertical gravity to achieve thinning on the horizontal surface.

Overflow High-alumina Glass Dominates The Market

Therefore, the density uniformity of the product is poor. The overflow method relies on gravity to pull in the vertical direction.It is less affected by surface tension, and the advantage of manufacturing high-alumina glass is inherent. The high-aluminum cover glass has disadvantages in density uniformity. On the one hand, it affects the performance of the glass cover. Brand manufacturers are more willing to use the overflow method high-aluminum glass cover substrate for high-end products—– Corning’s “Gorilla” glass cover. On the other hand, due to the uneven density, the glass tends to warp during the strengthening process in downstream processing plants.

The processing yield of float glass is lower than that of overflow high alumina glass. The yield rate of the glass cover processing plant directly affects its profitability. Therefore, the price of the overflow high-alumina glass cover substrate is reasonable. Cover glass processing manufacturers are also more inclined to purchase high-alumina glass cover substrates manufactured by the overflow method. All in all, the overflow high alumina glass cover substrate is the best solution for manufacturing the glass cover substrate based on the combination of process and formula. From the current product parameters of several major high-aluminum glass cover substrate manufacturers. The performance advantages of overflow high-aluminum glass cover substrates (such as Corning “Gorilla” glass cover) are obvious. This is also the reason why the high-end glass cover substrate market is monopolized by Corning “Gorilla” glass cover.

Touch Screen Cover Glass

The Touch Screen Cover Glass Substrate Is The Most Profitable Link In The Industry Chain

The traditional touch screen cover glass industry chain is composed of the upstream—cover glass substrate midstream—cover glass processing, and downstream—sensor and touch module factories. The cover glass processing factory purchases the cover glass substrate for a series of processing such as cutting and strengthening, and then hands it to the touch factory for sensor production and module bonding (OGS because we make cover glass directly on the sensor . So it is usually touch The factory develops to the middle reaches to complete the cover glass processing . And sensor production or the cover glass processing plant develops downstream to complete the glass cover processing and sensor production). Downstream sensor production and touch module manufacturing due to the mature industry and sufficient supply, coupled with the emergence of new technologies In-cell and On-cell. They have led to intensified industry competition and profitability has weakened year by year.

Due to the low technical barriers in the processing of glass cover plates in the middle reaches, it is more to compete with the strengths of enterprises in terms of human proficiency, scale and response speed. In addition, the downstream touch factory began to develop glass cover processing business. At present, the small-scale cover glass processing manufacturers are in a poor situation and their profitability is not high. The cover glass substrate industry is at the top of the industry chain and has barriers to entry. At present, it is still an oligopolistic market. Corning and Asahi Glass almost control the market . It is the most profitable link in the industry chain. At present, Corning’s “Gorilla” glass cover has a gross profit margin of approximately 80-90%.


Market Demand Growth For Touch Screen Cover Glass Substrates Is Still In The Fast Lane

In the past two years, the popularity of the smartphone and tablet computer market has led to a rapid increase in the demand for glass cover substrates. The increase in the number of shipments of both will still be one of the driving forces for the growth of cover demand in the future. So the gradual increase in the penetration rate of touch in ultrabooks and AIOs . And the expansion of the average size of mobile phones are also new driving forces for the growth of demand for glass cover substrates. The market demand growth of downstream glass cover substrates is still fast.


The Overflow High-alumina Cover Glass Has The Best Performance, Occupying The High-end Market

In recent years, with the continuous innovation of display technology. Display products have gradually developed in the direction of large screens, flatness, thinness, high definition, energy conservation and environmental protection. The flat panel display glass substrate is the core product in the display touch industry. Because of its high investment threshold, high technical requirements. And what’s more,  overseas glass substrate companies’ long-term strict sealing lock on core technologies. As a result, domestic panel companies mainly rely on imports to solve the source of flat panel display glass substrates.

At present, only a few companies in the world, including Corning, Japan’s Asahi Glass, Electric Glass, AvanStrate (formerly NHT), and China’s Tunghsu Group. They have a complete set of production technologies for flat panel display glass substrates. In the field of high-aluminum cover glass substrates, currently only a few companies in the world can produce them. For example, Corning of the United States, Asahi Glass of Japan, Schott of Germany and NEG of Japan, etc., the entire industry is in a highly monopolistic state. The result of the monopoly naturally caused the lack of bargaining space. And also put a heavy burden on the mainland touch screen companies.

The Cost Of  Touch Screen Cover Glass Increase

High-aluminum cover glass substrates account for 13%-18% of the total cost of touch screen manufacturers. While domestic substrates are at least 20% cheaper. Therefore, the 20% spread will increase the net profit margin of panel manufacturers by 1.5%-1.8%. Last year, the net profit rate of touch screen manufacturers was generally about 3%-5%. And the 10% difference was equivalent to more than 50% of the net profit of panel manufacturers. The attractiveness of domestic high-aluminum cover glass substrates is undoubtedly huge. It is worth noting that due to the high tariffs, packaging, transportation and storage costs of imported flat-panel display glass substrates. The production cost of touch screens has also increased accordingly.

Therefore, the localized supply of high-aluminum cover glass substrates. It has become one of the bottlenecks for the healthy development of the mainland touch screen industry. The import substitution potential of the mainland high-alumina glass substrate market is huge. The cover glass is an important component of the touch screen. In the industry chain, the gross profit rate in this field is at the high end.


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