2019 is the first year of folding mobile phones. Samsung, Huawei and Ruoyu have all released folding screen mobile phones. Next, other mobile phone manufacturers will also release folding screen mobile phones one after another. Transparent polyimide (CPI) has the advantage of flexibility, which makes CPI an essential material for folding screen mobile phones. However, the glass manufacturers that originally dominated the mobile phone cover market do not want to lose the folding screen mobile phone market. Corning disclosed to AVC industrial chain insight that Corning is developing an ultra-thin and flexible glass suitable for foldable equipment. So far, the technology has been successful in the R & D stage for 125 microns to 35 microns. This groundbreaking glass will not be damaged after thousands of bends and will remain flat. Corning further pointed out that "Corning and its customers are conducting sample analysis on this ultra-thin and flexible innovative glass. We will also work with our customers to optimize the equipment system to meet the customers' continuously upgraded design needs."
Corning has always been a supplier of glass covers for Apple mobile phones. This time, the customer of Corning's foldable glass may be apple. According to supply chain sources, Samsung display has supplied some samples of 7.2-inch foldable panels to apple. Apple is also developing foldable phones.CPI cover plate is not perfectAt present, all foldable screen mobile phones use transparent polyimide (CPI). Samsung folding screen mobile phone adopts Sumitomo chemical CPI, and Rouyu folding screen mobile phone CPI is provided by Kolon industry. The cover plate of foldable screen mobile phone must achieve high transmittance, low haze, scratch and abrasion resistance, good flexibility and high stability. Among the currently available materials, the rigid glass cover plate can not meet the requirements of foldable screen mobile phone, and CPI has become one of the necessary materials for foldable screen mobile phone.
CPI has certain advantages, such as high temperature resistance, low coefficient of thermal expansion, thickness uniformity and surface roughness. However, to be used in folding mobile phones, the requirements are higher, and the hardness and light transmittance need to be enhanced. Therefore, CPI needs to be coated with hard coating resin to enhance the hardness. At the same time, the light transmittance of CPI for folding mobile phones needs to be at least 88% to avoid fog, opacity and small black spots on the mobile phone screen. However, CPI is not perfect. Many people in the industry pointed out that CPI has poor scratch resistance and is prone to scratches. Hu Wei, general manager of donglihua, pointed out that CPI has poor impact protection ability. When it is hit by external forces, it can not play a protective role, and the flexible display on the inner side is easy to be damaged. Moreover, PI has poor rigidity and flatness. When reflecting, it is wavy, and the optical effect is not as good as that of glass cover plate. Corning also said that compared with other alternative materials such as plastics, the ultra-thin and flexible glass of Corning foldable equipment has better durability, scratch resistance and high-quality optical clarity. And the glass will not change color or fine lines due to folding or high temperature and high humidity, so as to ensure outstanding optical clarity. Hu Wei believes that the thickness of windable ultra-thin reinforced glass is less than 0.1mm, which can effectively solve some shortcomings of CPI, but the strengthening performance of glass needs to be further improved. Therefore, while looking for glass solutions, donglihua synchronously develops coating materials to assist in improving glass strength through coating, so as to meet the needs of constantly updated products and technologies.
Can flexible glass replace CPI?Corning is developing foldable glass. The glass solution is not Corning willow glass or Corning gorilla glass, but a new glass solution tailored to the unique design needs of foldable equipment.
Corning is expected to mass produce this glass when foldable mobile phones become the mainstream in the next few years. Although Apple has not disclosed its foldable phone plan, the company has been using Corning Glass since the launch of its first iPhone. John Bayne, senior vice president and general manager of Corning, said: "We have sent glass samples to customers for testing. They can be used, but they can not fully meet all requirements. People either want our glass to have better fall resistance or our glass to have a smaller folding radius. We can meet any of their requirements. However, the key problem now is to meet them at the same time "The thickness of the glass currently used by the company is 0.1mm and the radius of curvature is 5mm." Bain said: "the technical challenge behind the problem we are trying to solve is that you should not only maintain a small bending radius of 3 5mm, but also increase the damage resistance of the glass. This is the problem we are facing now." Foreign media also interviewed Professor John Mauro, who is currently studying at Pennsylvania State University. He used to be an employee of Corning. He said that the current foldable mobile phones use plastic polymers because glass is not technically ready for foldable screens. Mauro said: "This polymer is more flexible and easier to bend at the same thickness. The molecules of this polymer are easier to rearrange in response to pressure. The structure of glass is rigid." Mauro said that Corning's estimate of how long it will take to produce foldable glass may be a little conservative. Corning previously stressed that the folding screen cover always needs to make a balance and trade-off between durability and small folding radius. At present, no material can achieve the best of both worlds, and mobile phone manufacturers may focus on durability. Not only Corning, but also other glass manufacturers are opening Hair curved glass. It is understood that Japan electric nitrate is also developing foldable glass cover plate. Asahi Glass, electric nitrate (NEG) Schott has developed glass with a certain curvature, mainly for the automotive market. Hu Wei, general manager of donglihua, believes that at present, there is no production capacity of windable ultra-thin reinforced glass in the industry, and terminal manufacturers can only use CPI for the time being. In the future, with the determination of the trend of folding screen and the increase of usage, it is believed that windable ultra-thin reinforced glass will soon replace CPI.
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