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Huawei mate X was fired to 100000 yuan: why is folding screen mobile so difficult?

via:驱动之家     time:2019/11/18 22:32:38     readed:52

On November 15, Huawei mate x, a 5g folding screen mobile phone, was officially launched and was highly praised by the market. The mate x, priced at 16999 yuan, was sold out in one minute, which is hard to find in the market.

Then mate X was quickly fried by cattle to more than 30000 yuan, up to nearly 100000 yuan, which is really amazing. this

Day mate x is on sale again, still sold out in a short time.

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The reason why Huawei mate X was fired is mainly due toThe supply is very limited.

Similarly, Samsung's Galaxy fold, which has been sold twice recently, has also been sold out in a short time, but the price has not been greatly hyped like Huawei's mate X.

It's mainly because Galaxy fold took a long time to test and stock up before it went on sale.Previously, it was reported that Samsung Galaxy fold had hundreds of thousands of units in stock.

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However, even so, the stock volume is far lower than the stock volume of Samsung's main models, which are often millions of units.

The basic reason is that the folding screen mobile phone is too complex, with many new technologies and parts applied, which is difficult to assemble, high testing requirements, and many key parts with limited production capacity, so that the capacity of folding screen mobile phone is also limited.

In addition, due to the high cost of folding screen mobile phones, if a large amount of money is needed for stock up, it will be very huge, and it will face a large market risk (after all, it is a new product form, so it is still unknown how acceptable the market is).

Let's take a look at the supply chain of folding screen mobile phones and see how difficult it is?

I. in the first year of folding mobile phones, major mobile phone manufacturers stepped up their layout

(I) Samsung and Huawei lead the trend of folding screen mobile phones

Smartphone industry ushered in

In February 2019, Samsung and Huawei have successively released its first version of the folding screen: Galaxy Fold and Mate X, and appeared in the World Mobile Communications Conference (MWC) to open up

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▲ Samsung Galaxy fold (left) and Huawei mate x (right)

At the end of September, Xiaomi launched a very stunning

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▲ millet mix alpha

On November 14, Lenovo's Motorola also officially released its first folding screen phone.

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New version of Motorola Razr

In addition, apple, LG, oppo, ZTE, Microsoft, Google and other manufacturers seem to be actively preparing to launch their own folding screen products.

(II) folding screen mobile phones are expected to lead various upgrades

Samsung Galaxy fold and Huawei mate x, which are already on the market, adopt different folding schemes. Samsung adopts internal folding, while Huawei adopts Eagle wing asymmetric external folding.

Compared with the external folding mode, the internal folding scheme has higher requirements on the curvature radius and greater difficulty in technical implementation in order to achieve a better fit between screens after folding. But in turn, the screen will be exposed to the outside in the way of external folding. The screen at the folding place is easier to be broken and the maintenance cost is higher.

Samsung was expected to officially launch Galaxy fold in April this year, but in the media evaluation, two days after the trial, there were problems such as screen junction bulge, flash screen, black screen, etc., so Samsung didn't officially launch Galaxy fold in South Korea, Britain, the United States and other countries until September.

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Breaking through the limit of screen proportion, the advantage of large size of folding screen is prominent. In recent years, driven by the overall screen consumption demand, mobile phone manufacturers around the world have launched various technical routes to improve the screen share. However, due to the immature technologies such as screen sound, hole digging screen, the single screen share has gradually reached the limit. At present, the share of smart phone screen can reach up to 94%.

Compared with traditional smart phones, folding screens increase the display area by nearly 50%, and increase the number of screens at the same time. Consumers can choose to use single screen or multiple screens in combination, which not only meets the needs of daily single hand holding, but also integrates the functions of tablet and mobile phone to achieve multi task simultaneous operation, which is expected to provide new growth points for major mobile phone manufacturers.

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Samsung's Galaxy Fold folds with a 4.6-inch secondary screen (resolution 840 x 1960) that handles simple tasks and status displays and is expanded into a 7.3-inch tablet (21 x 9, resolution 1532)

Compared with the S-series flagship Galaxy S10 released in the same period, it can be found that the Galaxy Fold has an obvious advantage in terms of display area and battery capacity. In addition, the second folding-screen mobile phone, which is currently being developed by Samsung, is likely to use ultra-thin glass (UTG), the size of which is only 3 percent of the traditional mobile phone display glass, and can protect the inner screen of its folded-screen mobile phone, thus improving the durability of the phone's screen.

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The Huawei Mate X is designed with an asymmetric valgus, with a 6.6-inch main screen (19.5:9, resolution 2480) after folding

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In addition, Huawei's Mate X is equipped with a dual-card design that supports 4G and 5G networks, respectively, and has been upgraded in terms of charging rate, with built-in 4500mAh batteries and 55W super fast charging. Huawei's first 5G flagship machine, the Mate 20 X, has a screen size of 7.2 inches and a resolution of 2244.

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Compared with ordinary smart phones, the cost of raw materials for foldable screen phones is mainly reflected in the display screen, hinge, PCB, battery and other parts.

According to IHS, compared with Samsung Galaxy Fold and Galaxy S 10, the total cost increased by 30%. Due to the increase of the number and area of, Galaxy Fold display screen, the cost of display screen is 77% higher than that of Galaxy S10, which is the main source of cost increase. At the same time, to meet collapsible needs, the cost of PCB rose 14%, and the cost of components such as batteries and hinges rose 120%.

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The display accounts for about 30% of the price of folding mobile phones. According to Samsung, the price of the new version of Galaxy fold, which is listed overseas, is 599 US dollars (about 31% of the price of the whole machine) for screen replacement and 99 US dollars for back cover replacement. In contrast, iPhone 11 Pro Max and Samsung note 10 plus screen replacement costs $279 and $329, respectively.

One of the core technologies of foldable mobile phone: flexible display

Folding screen mobile phones should be folded and bent more than 200000 times to maintain a 5-year service life. The core difficulty lies in the display screen and hinge technology. In order to ensure the folding of the folding screen more than 200000 times without any problem, the thickness of the display module including multi-layer structure shall be reduced as much as possible, and the composition structure of the screen module shall be enhanced as much as possible, the core of which is to improve the performance of the cover material, substrate film, polarizer, nano silver wire, OCA glue and other parts. At the same time, the precision, reliability and bending resistance of hinge are much higher than that of notebook computer.

(I) PI film and other flexible materials will replace rigid cover glass

The foldable screen cover plate needs light and thin flexible materials. At present, the smart phone display cover mainly adopts Corning gorilla cover glass, which is easy to break even though it can achieve a certain degree of bending. The folding screen needs to meet the needs of repeated bending. It is impossible to use glass as the protective layer, and the thickness should be less than 0.5cm. The cover glass can be 0.35mm, but it can only bend a certain shape, and it can not be completely foldable. Therefore, new flexible materials need to be developed.

The thickness of AMOLED display module will decrease from 1.45MM of hard screen to 0.56mm of flexible folding screen. Materials such as cover glass, polarizer, OCA optical glue, touch layer, packaging substrate layer and hard protective film need to be thinner or use ultra-thin flexible materials.

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PI film and UTG are expected to replace ordinary glass as substrate covering materials for display screen. Rigid OLED uses glass as base plate, which can block water and oxygen from entering the corrosion circuit inside the panel. However, the traditional glass base plate is rigid material, which is not suitable for flexible display. The potential substrate materials can be ultra-thin glass (UTG) with elasticity, or polymer film: transparent polyimide film (PI film or CPI) or polyester film (PET).

PI film is a substrate material suitable for folding screen at present. PI film is superior to ultrathin glass in low bending radius, durability and surface hardness. However, compared with glass, CPI film has many disadvantages, such as low transparency, plastic sense, easy to scratch and so on. The surface hardening treatment can increase the surface hardness of PI film, keep the flexibility and make the material more glass texture, but it is more difficult for PI surface hardening treatment. Although the transmittance of pet is high, up to 90.4%, it is easy to produce plastic deformation under multiple bending. At present, more PI materials are used in folding screen and less PET film is used. Compared with polymer substrate, UTG substrate has better light transmittance, heat resistance and surface hardness due to its physical properties.

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PI film has excellent heat stability, which can meet the requirements of high temperature process such as electrode film deposition and annealing in the process of display screen. PI film itself is relatively soft. After hard coating treatment, it has good scratch resistance and wear resistance, meets the requirements of folding screen repeatedly, and is light, thin and transparent, so it is suitable for the manufacturing requirements of flexible screen and folding screen.

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The market of transparent polyimide film (PI film) is dominated by the United States, Japan and South Korea, and the main manufacturers include DuPont, Jinshan electronics, Changchun Gaoqi, Mitsubishi Gas, Dongli DuPont, Toyo textile company, Mitsui chemical and Korean Kolon. Japan accounts for 95% of the global production of transparent polyimide films. MGC is an important producer of transparent polyimide films in Japan, which first industrialized polyimide films. SKC and Kolon are also actively developing transparent polyimide films. SKC is in mass production in 2017q2 and Kolon is in mass production in 2018q1.

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(II) OLED polarizers for folding screen are developing towards light, thin and flexible

OLED of folding screen is required to improve the optical performance, and polarizer is required to maximize the optical performance, and at the same time, it is required to greatly reduce the thickness. According to Samsung SDC conference, the thickness of polarizer used by Galaxy fold is 45% lower than before. Polarizer is a kind of polymer composite film, which consists of polarizing film, inner protective film, pressure-sensitive adhesive layer and outer protective film. It is mainly used for flat panel display (TFT-LCD, OLED). PVA film is the core material of polarizing function in polarizer. Polarizers can be classified into transmission polarizers, reflection polarizers, semi transmission and semi reflection polarizers and compensatory polarizers according to their functions.

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TAC and PVA account for the main part of polarizer cost.

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The manufacturing process of polarizer mainly includes extension method and coating method, including dyeing, extension, lamination, coating, precision cutting and other links, in which the formula of dyeing material is the key technology.

At present, the extension method is the mainstream technology. The production technology is divided into two categories: dry process and wet process. In the wet drawing process, the drawing ratio is easy to be increased and the color is even. The polarizer produced is superior to the dry drawing process in terms of tone uniformity and durability. The advantages of dry drawing process are that PVA film with larger width can be used for processing, and the production efficiency is higher. Japanese, Korean and Chinese manufacturers generally adopt wet extension process.

The basic performance indexes of polarizers mainly include: optical performance, durability, bonding performance, appearance performance and other special properties. The basic structure of the polarizer for OLED is divided into the polarizing part and the functional compensation part. The ideal polarization state of the polarizer needs to be greater than 99.9%, and the transmittance reaches more than 45%. The compensation part requires full wavelength compensation of visible light.

OLED display of folding screen requires the polarizer to be flexible, light, reliable and scratch resistant.

In terms of bendability and lightness, in order to match the bending and opening and closing functions of OLED panel of folding screen, the polarizer should be thin enough and meet the bendability of hundreds of thousands of times, which is thinner and more bending resistant than TFT-LCD.

Flexible and thin OLED requires that the thickness of compensation film is much lower than TFT-LCD, and the thickness of liquid crystal compensation film can reach 2-10 μ m, which is expected to become the mainstream choice of folded screen polarizers. The industry's requirement for the thickness of normal OLED polarizer is 60-70 μ m, and the bending performance needs to meet 100000 tests under the condition of 2 mm curvature. The folding screen has more stringent requirements on the bending performance.

In terms of reliability, the folding screen designed with external folding structure is difficult to fit perfectly at the rotating shaft, and the polarizing plate is in the outermost part of the display screen, which requires higher requirements in high temperature and humidity resistance than normal mobile phones.

In terms of scratch resistance, because the screen is large, the user has direct contact with the surface of the polarizer, and the base plate is PI film and other flexible materials. If there is no hardening treatment, the surface is prone to scratch and affect the screen display, but also to meet certain friction resistance requirements.

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Polarizers are currently monopolized by Japan, South Korea, the United States, Taiwan, etc. The United States is mainly DuPont, 3M, and Japan is mainly Nippon electric, Sumitomo chemical, Japanese synthetic chemical and other companies. Koreno, a Korean enterprise, imports semi-finished products from Japan and then produces polarizers through post processing. LG Chemical has its own technology, accounting for 25% of the polarizer market. Domestic production enterprises are mainly Shengbo photoelectric and Sanli spectrum. The production of ultra-thin polarizers mainly includes Ridong electric and Sumitomo chemical.

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More than 80% of the demand for polarizers comes from TFT-LCD. According to his, in 2018, AMOLED polarizers will have a shipping area of 9.5 million square meters, which is expected to grow to 13.9 million square meters in 2019. Folding screen mobile phones will become a new growth point of OLED polarizers due to an increase of more than 70% in display area.

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(III) touch screen will adopt new flexible electrode materials

A new flexible electrode material will be used in the touch layer of folding screen. Indium tin oxide (ITO) is the mainstream touch electrode material at present. Due to its limited bending performance, after many times of bending or large-scale bending, the resistivity will rise significantly and it is easy to fracture, so it is difficult to be used in flexible touch screen and medium and large touch screen.

Flexible materials such as metal mesh, nano silver wire, carbon nanotubes, graphene, conductive polymer and so on have excellent conductivity, and are expected to replace Ito in the flexible touch screen, especially the metal mesh and nano silver wire. Carbon nanotubes and graphene are difficult to be produced on a large scale with high cost, so they are not suitable for folding screen production temporarily. Metal grid and silver nanowires have both good performance and mass production capacity, and have been put into use.

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Metal grid is a touch technology that can press the conductive metal grid pattern on the flexible film and cover the silver, copper and other metals to realize conduction, with excellent bending performance. Metal grid suppliers mainly include ATMEL, ofig, Toray, Fuji, etc.

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Nano silver wire is a kind of nano silver wire conductive film which is coated with nano silver wire ink material on the film material or glass substrate and formed with the help of laser lithography technology. Nano silver wire has the advantages of low cost, good stability, excellent conductivity, light transmittance and flexibility. At present, suppliers mainly include Hefei microcrystalline, Zhuhai nacrystal, cambrios (TPK holding), Suzhou nofi, c3nano, Huake Chuangzhi, etc.

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(IV) the volume and price of OCA optical adhesive are rising

OCA optical adhesive is a kind of double-sided adhesive tape, which is the best adhesive for touch screen material, and requires high cleanliness. In addition, OCA optical adhesive has the advantages of no bubble, water resistance, high temperature resistance, UV resistance, high cleanliness, high light transmittance, low haze, high adhesion, no crystal point, etc., with high thickness uniformity and flatness, its refractive index is 1.48 (close to glass, PC, PMMA), light transmittance is 92% to 99%, long-term use can prevent yellowing, aging, fogging, separation from the adhered surface and occurrence Bubbles and other problems. OCA optical glue is mainly used for electronic paper, touch screen, lens assembly, display panel assembly, glass, etc.

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The function of OCA optical glue in the display screen: reduce glare and AMOLED light loss, increase brightness of the display, increase contrast and transmittance, avoid Newton ring, and expand the visible area.

OCA optical adhesive adopts die-cutting processing technology, which has very high environmental requirements. The process of membrane replacement requires a class 1000 or class 100 dust-free room. OCA needs to adopt different die-cutting structures according to different fitting methods. Die cutting is used for 7-inch and liquid glue is used for 10-inch and above. The OCA fitting methods include: soft to hard fitting, sensor surface fitting, OCA attaching machine with automatic aligning function, and vacuum laminating machine for attaching the attached OCA sensor to the cover plate material.

The amount of OCA optical adhesive is doubled, and the bending resistance is improved. Because the display area of folding screen becomes larger, the OCA optical glue required is greatly improved compared with ordinary mobile phones. The folding screen has more than 200000 times of bending. The common OCA adhesive has great fluidity and general cohesion, which is easy to deform after extrusion. The folding screen requires that the bending resistance and reliability of the OCA optical adhesive be greatly improved. The OCA optical adhesive also needs to maintain the fluidity and not fall off during the opening and closing process.

At present, the main suppliers of OCA glue used for folding screen include 3M, Samsung SDI, Mitsubishi and South Korea TMS. According to DIGITIMES, Samsung SDI exclusively supplies OCA glue for Samsung folding screen mobile phones. Domestic suppliers mainly include Fuyin group, fansaite, Xinlun technology, Jiayun optics, Baoli new material, Huigu chemical, etc. According to wind, in 2017, the global OCA optical adhesive market scale is close to US $900 million. With the increase of OLED penetration and the growth of panel display industry, it is expected that the OCA optical adhesive market scale will reach US $1 billion in 2020.

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(V) the penetration rate of folding mobile phones will increase, and the demand for folding screens will continue to grow

The folding screen market is in full swing. By 2021, the number of mobile phones with folding screens is expected to reach 18 million. According to Bloomberg, Samsung is developing a second folding screen mobile phone, which adopts an internal folding scheme similar to the traditional flip phone. Compared with Galaxy fold, Samsung's second folding screen mobile phone will be lighter and cheaper due to its more mature technology, so as to further expand the consumer demand of folding screen mobile phones. According to IHS forecast, the number of foldable mobile phones shipped in 2019-2021 will be 1.5 million, 8.3 million and 17.5 million. By 2025, the number of foldable mobile phones will rise to 53.4 million, with CAGR of 81% and penetration rate of 3.4%.

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Global OLED panel shipments are expected to reach 768 million pieces this year, of which Samsung, relying on nearly 10 years of R & D experience, has occupied more than 90% of the global market share of high-end OLED panels, monopolizing the entire market supply. Qunzhi expects that the delivery penetration rate of flexible AMOLED will reach 18% in 2020, more than 300 million pieces, and the output value will reach 21.4 billion US dollars. However, BOE Chengdu 6-generation full flexible AMOLED production line has started mass production and is expected to become a supplier of domestic android models.

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Domestic panel manufacturers, such as BOE, vicino, Shenzhen Tianma, etc., are also continuously laying out AMOLED production lines In 2019, there will be 6 new AMOLED production lines planned for mass production, including BOE Mianyang 6th generation line, Huishang 6th generation line, vicino Gu'an 6th generation line, Ruoyu Shenzhen 5th generation half line, Huaxing photoelectric Wuhan 6th generation line and Xinli Anhui 6th generation line. By 2020, there are more than 13 AMOLED production lines planned for mass production in China.

According to BOE, after nearly a year and a half of yield climbing, the yield of Chengdu 6-generation flexible AMOLED production has exceeded 70%, but the flexible OLED screen produced by BOE is not only used for mobile folding screen, but also for other fields such as wearable devices. At present, BOE is expected to become the first panel manufacturer in China with mass production of millions of mobile folding screens after Samsung. In addition, LG's LGD e66 fully flexible AMOLED has been mass produced, but its capacity is limited. According to ovirevo, in 2019, the demand of smart phones for OLED will be about 450 million pieces, including 200 million flexible screens. Mobile phone manufacturers led by Samsung and Huawei will consume about 1.1 million folding screens.

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According to the existing information, the folding screen of Samsung Galaxy fold is supplied by Samsung display; the folding screen of Huawei mate x is supplied by BOE; the previously exposed double folding screen mobile phone of Xiaomi and the surround screen of mix alpha are all from vicino; the folding screen used by Motorola's new version of Razr is also supplied by BOE.

3. Key technology of folding mobile phone 2: hinge

(I) core design of hinge and folding screen

In 1982, IBM designed a hand-held computer with flip-screen and open-and-close. In 1985, Toshiba introduced a laptop with a rotating shaft. The start of the laptop was heavy until the first ThinkPad was released in 1992, the hinge of the notebook was extended to a stable fixed screen and the maximum volume was reduced. Then, the opening and closing angle of the rotating shaft of the notebook computer gradually achieved 180 degrees from 130 degrees,360 degrees,

The design of hinge is the core of folding screen. The function of the hinge is to support the rotation and connect the screen. In order to achieve a better fit of the screen after folding and minimize the gap between screens, the rotating axis of the folding screen should not only be light, flexible and stable in performance, but also take into account the circuit connection, wiring and heat dissipation related to the folding screen, and also meet the user's holding experience. In addition, each time the screen is folded, it will cause certain wear to the rotating shaft. Therefore, the rotating shaft should not only have high rotation accuracy and friction coefficient to support the folding and rotation of the screen, but also be higher than the hinge of notebook computer in precision, durability and strength.

In the hinge part of Samsung Galaxy fold, four spring bayonets are used to lock the screen in the unfolding state. A central hinge drives the gear system to make the two halves of the mobile phone unfold synchronously. Two hinges, which are respectively fixed at the top and bottom of the central axis, absorb the torque, so that the screen will not fold after folding. Huawei mate X has set up a 4-layer structure, from top to bottom is the screen protection layer, bendable flexible screen, soft rubber support plate, rotating shaft (composed of more than 100 parts), which adopts Eagle wing folding, realizing a good experience of single machine with a thickness of 5.4mm and a folding thickness of only 11mm.

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▲ Samsung Galaxy fold internal hinge (picture source: ifixit)

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The appearance of folding screen shaft has experienced from the physical movement principle to the design of sub function module, and then to the selection of specific materials. The production process is very difficult. At present, the yield of hinge produced by Samsung is low, which is lower than that of flexible screen. The estimated cost is between 30-40 dollars, and the cost of hinge sample provided by domestic manufacturers is about 40-50 dollars.

The main reasons for the high cost of folding screen hinge are as follows: 1) dozens of precision metal parts are manufactured by MIM, stamping, CNC precision machining and other processes; 2) the high size and assembly accuracy of metal parts lead to the increase of process complexity; 3) the large number of parts and complex assembly process lead to the increase of accumulated tolerance, and the yield is much lower than that of ordinary metal middle frame.

The structure design of the rotating shaft is complex and consists of hundreds of precise components. According to the shaft patent published by Samsung and Huawei, Huawei adopts the technical route of linking the screens on both sides by means of gear engagement, which can realize 0-180 degrees of free folding. Samsung's shaft adopts the linkage design opening and closing screen of shaft and blade. After the screen unfolds, the shaft will be hidden in the fuselage, which can't be seen from the back.

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Oppo filed a hinge patent in the United States in February 2019. The foldable mobile phone displayed in the patent is mainly composed of a rotating mechanism, a decorative component, a first body, a second body, a support component, a display panel component, etc.

Samsung Galaxy fold has made a lot of optimizations on the hinge: the top and bottom of the hinge area are reinforced with protective caps to avoid the entry of external particles such as dust, while maintaining good folding performance; the top protective layer of infinity flex display is extended to the frame, and other metal layers are added below to enhance the protection of the display; the space between the hinge and the main body is increased In one step, the connection is more smooth.

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(II) hinge industry chain: dominated by overseas enterprises

The supply chain mainly consists of Korean and Taiwanese manufacturers. According to South Korean media, Korean manufacturer khvatec provides Samsung Galaxy fold with exclusive hinges. Guangdong Jinli transmission provides Samsung Galaxy fold with a micro drive structure. Taiwan Qihong provides Huawei mate x with hinges. With the maturity of folding screen hinge technology and the improvement of yield, the hinge cost is expected to continue to decline.

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At the new product launch on October 2, Microsoft released two double screen folding products: the tablet surface Neo and the smartphone suface duo. Although they are only double screen folding, they are not really folding screen products, but Microsoft's rotating shaft design is quite exquisite. 360 degree metal hinge design is used at the screen connection, and micro teeth with hinge torque system are used The wheel can realize the complete fit of two ultra-thin screens with the same thickness after folding, without any gap in the middle. The surface Duo is equipped with two 5.6-inch screens that can be folded into multiple angles through a 360 degree hinge design, and then expanded to form an 8.3-inch display.

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MIM is one of the key technologies to realize high precision shaft. In order to achieve the good performance of the shaft, the preparation of materials is very important. MIM (metal injection molding) and liquid metal will play a key role. MIM is a new type of near net powder metallurgy forming technology, which introduces modern plastic injection molding technology into the field of powder metallurgy. Using metal powder as raw material, MIM can produce all kinds of precision parts at low cost through forming and sintering process.

MIM has unique advantages in the preparation of near net shape products with complex geometry, uniform structure and high performance and high precision. Moreover, MIM can realize full-automatic and continuous operation in the production and preparation, with high production efficiency. At present, MIM is widely used in the shaft preparation of various electronic products. Apple also uses metal injection molding in the spindles of its new MacBook. MIM is generally made of iron-based materials and tool steel.

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Liquid metal is a kind of amorphous zirconium alloy material, which is different from crystal changing into liquid at fixed melting point. The physical properties of liquid metal are more similar to that of glass, and its viscosity will decrease with the increase of temperature, which means that liquid metal has strong plasticity at high temperature, and it is easier to control the structural characteristics during mold forming. Liquid metal has high strength, high dimensional accuracy and excellent molding ability, which can meet the ultra-thin design of complex structural devices, and the finished product has a beautiful appearance, and can greatly save the process cost of structural parts, which is very suitable for the preparation of folding screen shaft.

IV. folding screen mobile phone drives the consumption of battery, FPC and other parts to increase

(I) equipped with double cells and fast charging to improve the added value of single battery

With the increase of the display area of the folding screen, the power consumption will inevitably increase. How to ensure the endurance of the folding mobile phone is a difficult problem. Samsung and Huawei, for example, both adopt a dual cell solution, with one battery on each side of the fuselage. Samsung's two fast cell combination forms a 4380mah large battery, which supports fast charging, wireless charging and reverse wireless charging; Huawei carries 4500mAh battery, and uses 55W super fast charging technology, with a half-hour charging capacity of 85%.

In order to meet the requirements of fast charging and wireless charging, the cost of battery will inevitably rise, which directly increases the value-added of single battery. At the same time, because the folding screen is thicker than the traditional smart phone after folding, in order to ensure the light and thin of the mobile phone, the size of the battery should not be too large, so the traditional lithium battery may not meet the needs of the folding screen, and it is possible to work on the flexible battery in the future.

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▲ disassembly drawing of Samsung Galaxy fold, with two batteries inside

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▲ Huawei mate x is also equipped with two batteries inside

(II) double mainboard, increase the value of single component

Folding screen mobile phone dual screen, dual motherboard. Samsung Galaxy fold uses two screens, the PCB motherboard is twice as large as that of ordinary mobile phones, and the number of power management IC, RF chip, audio chip and other chips on the motherboard doubles. FPC quantity increased. The connection between the two screens depends on the flexible FPC, and the increase in the number of cameras also increases the FPC consumption. Samsung Galaxy fold uses two flexible cables with good layout to communicate the two halves of the device. In addition, waterproof materials, electromagnetic shielding parts, heat dissipation materials and other components will also increase significantly with the increase of main board parts.

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Samsung Galaxy fold is equipped with 6 cameras, of which 3 are rear mounted (12 MP telephoto, 12 MP wide-angle camera, 16 MP ultra wide-angle camera), 10 MP selfie camera and 8 MP RGB deep sense camera are in the folding screen, and 10 MP selfie camera is in the non folding screen. Huawei mate x also uses three Leica cameras.

Five, summary

With the folding screen from concept to mass production, the whole industry chain will usher in new challenges and opportunities. Compared with the traditional curved surface display screen, the flexible OLED screen has put forward new requirements in substrate materials, touch control, OCA optical glue, polarizer, FPC and other links. At present, there are Samsung, BOE, LG, Shenzhen Tianma, vicino, TCL group and other domestic and foreign companies with the mass production capacity of the flexible panel. At the same time, in order to meet the needs of folding, a new design of folding shaft is needed to reduce the wear caused by folding and improve the durability of the screen. Moreover, the size of the foldable screen mobile phone should not be too large, which requires that the various components of the foldable screen mobile phone should reduce the thickness as much as possible, which brings new challenges in the selection of materials and the improvement of the preparation process.

In addition, in order to ensure the user experience of consumers and truly realize the popularity of folding screens, it is necessary to achieve better screen fit in FPC, shaft design and other aspects, reduce the thickness of components such as polarizer, OCA optical glue, touch materials, and upgrade the battery and charging efficiency to improve the endurance, so as to meet the increased power consumption demand of the display area.

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