The development of smart phones If the advent of the first generation iPhone began to talk about the use of materials from the aluminum chassis with plastic, all the way to the present pure plastic shell and metal-based shell (due to communication requirements, the phone can not be pure metal shell) , And even multiple materials such as glass and ceramic can be seen as a result of competing efforts between different materials as smartphone technology advances and glass covers appear to be winning among many materials and the following is an analysis of the development of glass enclosures at all levels.
Good thermal conductivity of glass material
Plastic is a low-cost plastic material, but its texture is not good, and the thermal conductivity is low, which affects the heat dissipation. Therefore, it is only used in smart phones or mid- to low-end smart phones or in antenna openings on the back of metal chassis. Although the alloy is still the mainstream material of the chassis at this stage, however, Samsung has taken the lead in large-scale promotion of wireless charging and the replacement of glass back cover design. Coupling with the three major factors of the upcoming era of 5G era and high homogeneity of current smart phone appearance Driven by the non-metallic materials such as glass and ceramics began to become the market focus, but considering the cost, coupled with the metal material in the low-end smart phone penetration continues to rise, so the current glass or ceramic materials mainly appear in the high-end models .
The thermal conductivity of glass is better than plastic, but worse than metals and ceramics, in the electromagnetic shielding is a low shielding material; In addition, compared with plastic, metal or ceramic, the glass in the same thickness weight lighter, hardness To Corning's fifth-generation gorilla glass, for example, Mohs hardness of 7 to resist the daily wear of almost all kinds of materials.On the other hand, ceramic materials, texture, wear resistance and heat dissipation are better than the glass , But the current yield is still very low, making it expensive, not yet large-scale mass. So glass is currently non-metallic materials can take into account the quality, yield, cost and the ideal mass-produced mass.
Mobile phone glass cover in addition to continuous improvement through the material formula, or chemical treatment to improve the strength, the appearance also thanks to the emergence of flexible OLED thanks to the beginning of the current changes in the three major types of glass is 2.5D glass Curvature is machined by CNC, but 3D glass relies on the device to be bent, so there is a fundamental difference in concept and manufacturing process. In addition, in terms of visual effects, due to the curvature of the 3D glass at the boundary Light, so the screen will look wider than the actual width.
Due to the curvature of the 3D glass's inner edge, the border screen can be further stretched with a flexible OLED panel to make the overall screen size appear larger.
3D glass is expensive
Compare the cost of the three types of glass cover, the cost of 2D and 2.5D glass is not much difference, but up to 3 to 4 times compared with 3D glass, because 3D glass requires additional equipment and mold costs, and High technical requirements, low yield makes the high cost.
Then compare the cost of the main shell program, the cost difference between different shell programs is quite large, and because the glass itself is low in crispness, so the glass shell still needs to match the metal frame to enhance the strength, but the metal frame design is better than the metal The complexity of the case, the CNC processing time required for longer, it can be found on the average cost of the glass case than the metal case is higher.Although the current aluminum alloy-based metal chassis is still the mainstream of high-end mobile phones Materials, but high-end or above flagship aircraft models have begun to front and back glass back cover with metal frame program.From the global market to high-end mobile phones focus on the expected use of the glass case will lead the overall trend of mobile phones The average sales price increased.
Because 3D glass is much more expensive than 2.5D or 2D glass, manufacturers prefer to use 2.5D or 2D glass if they do not have the same high-cost, flexible OLED panel, otherwise they will not get better in industrial design Therefore, it is expected that the 3D glass will be bound to the flexible OLED, and the penetration of the 3D glass will have a certain direct relationship with the popularity of the flexible OLED.
Glass chassis industry chain
The overall glass chassis industry chain can be divided into upstream, middle and lower reaches of the upstream glass raw materials and equipment to provide manufacturers, the material part currently dominated by the United States and Japan manufacturers, bending machines are mainly Korean manufacturers, but carved Machine starts to see more and more Chinese manufacturers appear.The middle reaches of the glass and metal processing, currently dominated by Taiwan and Chinese manufacturers, especially in the glass processing part, the market share of Chinese manufacturers accounted for about 80% of the world .And the downstream is EMS foundries, including Foxconn, Heshun and Wistron, etc. From the cost structure, upstream materials account for about 27%, downstream manual assembly about 24%, midstream manufacturing (including equipment depreciation) accounted for up to 49%.
The middle reaches of the main cost of manufacturing accounted for nearly half of the glass and metal process because there are certain technical threshold there, through rate (the whole process of the first yield yield) low, resulting in high costs.
2D, 2.5D and 3D glass processing flow is the biggest difference between the 3D glass bending process more, so that the follow-up process to be fully processed on the surface. 3D glass processing technology is more difficult, associated costs are more expensive, but at the same time the added value of 2D And 2.5D high.
The reason why hot bending is difficult is that the thermal expansion coefficients of glass and graphite molds need to be consistent. If they are inconsistent, the glass may burst or bend to a wavy shape. Therefore, the bending is the most crucial step, which will determine the overall capacity and goodness of 3D glass As for polishing and printing, due to the surface, so the equipment and processes have higher requirements.Moreover, 3D glass and OLED fit, the required equipment is currently mainly provided by Japanese and South Korean manufacturers, Samsung's cover Even the glass-and-glass laminating equipment was designated by Samsung, which is likely to be used by handset brands in Japan and South Korea despite the high cost of 3D glass and OLEDs, due to the inability of Chinese manufacturers to meet the needs of handset brands. Of the equipment, after all, due to poor yield and scrap more damage.