What are the most talked about new smartphone technologies in recent years? In addition to 5G, full screen, of course, you have to count the folding screen! The transition from 4G to 5G will greatly improve the performance of mobile phones, and the appearance of folding screens will subvert the form of traditional rectangular mobile phones and make the large screens more portable by folding.
But if you want to make a folding phone, you need more than just a flexible screen. Protective glass is also necessary. The glass panel commonly used in smartphones cannot be folded, so mobile phone manufacturers and accessory suppliers have come up with various methods.
What is the difference between ultra-thin glass and ordinary glass? Ultra-thin glass, like glass that is often seen every day, is an amorphous metastable solid material with an irregular structure. Generally, it is made of a variety of inorganic minerals (such as quartz sand, borax, boric acid, etc.) as the main raw material, and a small amount of auxiliary raw materials are added. Its main component is silicon dioxide and other oxides, all of which are silicate double salts.
Ultra-thin glass is compared to ordinary flat glass, the difference is only in thickness. Generally, glass with a thickness of less than 1.5 mm is considered to be ultra-thin glass. According to the thickness of glass in real life, glass can be divided into six types:
Extra thick glass 19 ~ 30mm;
Super thick glass 12 ~ 19mm;
8 ~ 12mm thick glass;
Ordinary flat glass 4 ~ 8mm;
Thin glass 1.5 ~ 3mm;
Ultra-thin glass <1.5mm.
Among them, ultra-thin glass with a thickness of less than 0.5 mm has good flexibility. A sheet of A4 printing paper has a thickness of 0.095mm, and ultra-thin glass with a thickness of less than 0.1mm has bendability and is also called flexible glass.
Ultra-thin glass is light weight, high temperature resistance, impact resistance
Ultra-thin glass not only has the basic characteristics of glass, such as high transparency, electrical insulation, heat resistance, chemical stability, and gas resistance, etc., but also has unique characteristics such as light weight, high temperature resistance, impact resistance, and flexibility. Therefore, it has extensive application prospects in display panels, ITO (indium tin oxide) conductive film glass substrates, flexible display substrates, smart surfaces, OLED (Organic Light-Emitting Diode) lighting, and flexible solar cells, and will give new generations of electronic products. Changes in appearance and form.
With the rapid development of flat panel display technology, there is a huge demand for ultra-thin glass in the world market. In the past few years, the demand for ultra-thin glass in the international market has increased at a rate of 20% per year.
China's demand for ultra-thin glass is also increasing. It is estimated that the current annual demand for domestic ultra-thin float glass is about 50 million m2, and it is increasing at a rate of 15% per year. With the rapid popularization of smart mobile terminals and the growing demand for LCD panels, ultra-thin glass will be one of the most in short supply and the most promising products in China, and an important opportunity for glass material manufacturers. Production technology is very difficult, and its price is tens or even hundreds of times that of ordinary glass.
How is ultra-thin glass produced?
At present, the production methods of ultra-thin glass mainly include float method, overflow pull-down method, slit pull-down method and secondary pull-down method.
The float method mainly flows the molten, clarified, and cooled glass liquid into the tin tank smoothly and continuously under the control of the adjusting gate, and floats on the surface of the molten metal tin liquid. The glass liquid flows into the tin tank under the action of gravity Flatten, polish under the action of surface tension, float forward under the pull of the main drive, and realize the process of thinning the glass ribbon under the action of the edger to form ultra-thin flexible glass.
2.Overflow pull-down method
The overflow pull-down method is a hot technology in the current ultra-thin glass manufacturing, and it is also a bottleneck restricting the development of the domestic ultra-thin electronic glass industry. The overflow down-draw method mainly injects molten glass liquid into a wedge-shaped overflow tank, overflows the glass liquid from the overflow tank, and pulls down the molten glass integrated under the overflow tank to manufacture ultra-thin glass.
Except that the two outer surfaces of the glass ribbon produced at the end of this method are in contact with air, they are not in contact with any solids or liquids, that is, no groove bricks, lead bricks, turning rollers, no tin grooves, no grinding and other treatments are required; The flow direction of the molten glass is parallel to both sides of the glass ribbon formed, which is conducive to installing temperature adjustment devices on both sides of the glass ribbon, which is helpful to eliminate the unevenness of the glass plate surface and improve the quality of the glass plate surface.
3.Slit down method
The slit pull-down method mainly introduces molten glass liquid into a groove made of platinum-rhodium alloy, flows out from a slit at the bottom of the groove, and uses its own gravity and downward pulling force to make ultra-thin glass. The thickness of the glass prepared by this process can be controlled according to the draw capacity of the melting furnace, the size of the slit and the pull-down rate, and the warpage of the glass can be controlled according to the uniformity of the temperature distribution, which can continuously produce ultra-thin glass.
4.Secondary pull down method
The secondary pull-down method uses a preform glass preform prepared by a float process to be wound on a cylindrical winding roll, and the glass base material is conveyed vertically downward, and the glass is heated to near the softening point by a heating device, and the softened The glass substrate was extended downward to prepare an ultra-thin glass.
According to the domestic scientific research and the actual production of flexible glass, the secondary pull-down method and slit pull-down method of these methods are intermittent, low investment costs, easy to change the formula, etc., and are more suitable for research and development of research institute laboratories. Float method and overflow down-draw method have the characteristics of large-scale, large plate width, and continuous production. They are more suitable for large-scale industrial production and have the advantage of low cost in the industrialization process. Domestic float process technology and equipment are relatively mature, and the use of float technology has more development prospects. At present, it has been able to produce ultra-thin ordinary soda-lime-silica glass. With the further development and improvement of process technology and equipment, solving the problems in the production of ultra-thin flexible glass in float technology can accelerate the promotion of the application fields and scope of flexible glass.
No thinnest, only thinner
For a long time, the production of ultra-thin glass has been mainly based on the float process, but it is controlled by foreign companies. Leading technologies are mainly in the hands of CORNING, SCHOOT, Pilkington, AGC and NEG. As early as 2012, Corning, the world's most important supplier of touch panel glass for mobile phones, has released a method that uses a fusion overflow pull-down method and high-temperature rolling technology to produce an ultra-thin rollable screen glass with a thickness of 100 μm. And named it "Willow-Glass". Through chemical tempering treatment, it obtains high strength and strong bendability. The bendable radius is 5cm, and it can be rolled into a cylinder with a width of 1.3m, a length of 300m, and a diameter of 15.24cm. At the same time, it is lightweight, low-cost, and affordable. High temperature up to 500 ℃.
What is the current 0.12mm ultra-thin glass that can be mass produced in China?
Last April, a product produced by AHBB set a world record. At that time, the AHBB Glass Industry Design and Research Institute successfully pulled the world's thinnest 0.12mm ultra-thin float electronic glass, which once again refreshed China's ultra-thin electronic glass thin production record and filled the domestic gap again.
On September 4th, reporters were able to glimpse the world record-setting, only 0.12mm flexible touch glass.
0.33 mm, 0.15 mm, 0.12 mm … A piece of ultra-thin glass was rolled off the China Building Materials Bengbu Glass Industry Design and Research Institute, setting a new record for China's electronic glass development.
What is 0.12 mm? Nearly the thickness of a sheet of A4 paper. What is the hardness of 0.12 mm glass? When doing the falling ball test in the laboratory, the workers placed 55 grams of steel balls at a height of one meter and smashed into the ultra-thin glass freely. This impact is equivalent to the impact of a family car hitting a wall at a speed of 150 kilometers per hour, but the glass is intact.
Sun Yawen, the person in charge of the general management department of AHBB Information Display Materials Co., Ltd. introduced that this thin glass is the thinnest glass produced in the world using the float process. It has been mass-produced and used for mobile phones, computers and televisions. Display basic materials.
Sun Yawen said that because of technological breakthroughs and innovations, the international market price of ultra-thin glass has been reduced by 2/3. While reducing costs for enterprises, it has also ensured the security of the national electronic information display industry. Currently, 0.1mm flexible touch glass is under development.
This new material is expected to replace ultra-thin glass
Science and technology have been developing, and any product update cannot stagnate, and ultra-thin glass will also face various challenges. On the one hand, it is facing the challenge of breakthroughs in key technologies, and the challenge of ultra-thin glass is facing the trend of flexibility. With the continuous development of new display products, consumers are increasingly demanding for thinner and thinner devices, including mobile communication terminals. Storage space, long battery life, and a thin and light display have become the goals pursued by high-end device manufacturers. On the other hand, ultra-thin glass also faces the challenge of replacing new materials such as polyester plastic films. Compared with ultra-thin glass substrates, polyester plastic films have a thin and light weight, improve impact resistance, and achieve flexibility. Incomparable advantages. A few days ago, China's Huawei launched its first folding screen Mate X-5G mobile phone at a new product conference in Barcelona, Spain. It uses flexible OLEDs, which uses PI (polyimide) as the lower substrate instead of the glass substrate in rigid OLEDs; using thin films Packaging replaces glass packaging.
With the rapid development of the country's high-end manufacturing industry, ultra-thin glass will develop in the future in the direction of large size, high strength, high elastic modulus, small curvature radius, high yield and low cost, and its application fields will become more and more extensive. In the future, the display can be bent, printed and folded like a wallet. When not in use, it can be folded for easy carrying. When in use, it can be expanded to achieve a larger screen display. It can also be scrolled like a rolling curtain; it can even be stretched Shows, and polyester-based plastic film has a more obvious advantage in this regard.