The final assembly yield of the iPhone Duo is only just over 60%.
With only more than one month left before the official release, the mass production ramp-up of Apple's first foldable screen phone iPhone Duo has not been completed yet.
On September 17, a reporter from Jiemian News exclusively learned from people close to Foxconn's industrial chain that the current overall yield rate of Foxconn's assembled iPhone Duo units is only over 60%, with a small output for the first batch. In accordance with Apple's existing quality standards, it may take another half a year or even a full year for the overall yield rate to reach a mature level. "Now the supply chain is waiting for Apple to make a decision on whether to relax the quality requirements. Only if the quality requirements are relaxed can the large-scale mass production be promoted faster," the above-mentioned person said. The low yield rate is not entirely caused by an unsolved technology, but because Apple is mass-producing foldable screen phones for the first time, and the production line still needs to repeatedly adjust equipment, processes and parameters in actual operation. "The production line cannot be put into good operation directly just with technology and equipment, it needs to be debugged while producing."
The reporter from Jiemian News also learned from people in the industrial chain that in addition to the yield rate of Foxconn's unit assembly still being in the ramp-up phase, the OLED panels supplied by Samsung Display and hinge-related parts have also previously encountered problems such as insufficient yield rate, delayed delivery and scheme adjustment. Any delay in an upstream link will reduce the time reserved for subsequent assembly plants to debug the production line.
In the research report released by Mizuho Securities on September 3, it was also mentioned that the hinge specifications and screen crease problems have dragged down the mass production progress of Apple's foldable screen units, and Apple needs to weigh the quality standards to promote full-scale mass production.
A person from the industrial chain told the reporter from Jiemian News that this year's global stocking target of iPhone Duo is about 6 million to 8 million units. In contrast, for a mainstream Pro or Pro Max model, the shipment volume in a single product cycle usually reaches 20 million to 30 million units.
"The foldable phone is an independent model, and its shipment will not start until October this year, so the sales volume will not be particularly large," he said.
People from the terminal channels told the reporter that the sales guidance given by Apple exceeds 5 million units.
Hinges and creases are major obstacles to mass production
Apple has reserved a longer time for the mass production ramp-up of iPhone Duo than in previous years.
In the early morning of September 10, new Apple CEO John Ternus launched iPhone Duo at the press conference. However, this phone was not launched quickly like the new iPhones in previous years. Apple announced that iPhone Duo will open pre-orders on October 16 and be officially released on October 23.
Statistics from Jiemian News show that in the past five years, Apple's autumn flagship iPhone had an average interval of only about 3 days from launch to pre-order, and an average interval of about 10 days from launch to official release. The two intervals of iPhone Duo have been extended to 36 days and 43 days respectively, about one month longer than before.
Jiemian News learned that the delayed launch of iPhone Duo is first affected by the delivery pace of core components such as foldable OLED panels and hinges.
The foldable OLED panels used in iPhone Duo are supplied by Samsung Display. An analyst who has long focused on Apple's industrial chain said that the delivery time of relevant panels may be later than previously expected, and the subsequent unit assembly and production line ramp-up will also be postponed as a whole.
The hinge solution has also gone through adjustments. The reporter learned from the industrial chain that Apple once tested the use of liquid metal in some hinge parts, but the relevant solution still went through re-evaluation before mass production.
"Once the component materials or production processes are switched in the middle, other suppliers need to re-make samples, verify and produce, and new suppliers cannot immediately push the output to a high level," the above-mentioned analyst said.
Even without adjusting the solution, foldable screens and hinges themselves are not standard parts that are easy to produce. Compared with ordinary bar phones, they add new materials, structures and assembly requirements, which also makes the error control of the whole device manufacturing more difficult.
Judging from the prototype displayed at the press conference, the crease of iPhone Duo is less obvious than that of most foldable screen phones on the market, but it still does not reach the "perfect state" originally envisioned by Apple.
The crease is not a simple groove on the screen surface, but the result of the combined effect of screen materials, hinge structure and unit assembly.
Compared with ordinary bar phones, foldable screen phones not only add an inner screen, but also add a hinge composed of more than 100 parts. The errors between the screen, the hinge and the body must be controlled within a very small range, otherwise the final result may be deepened creases, inconsistent opening and closing resistance, local sag of the screen, and even affect the service life.
Judging from the technical solution disclosed by Apple and the situation learned by the reporter from the industrial chain, Apple splits the crease into three problems to solve: how to change the screen material, how the light reflects, and how the screen should be folded.
Among them, the special adhesive layer is responsible for releasing the bending pressure; the nano-texture on the surface reduces the visual presence of creases by dispersing reflected light; the hinge and support structure under the screen are responsible for controlling the bending track and flattening the center of the screen after unfolding.
These solutions are designed by Apple as a whole, but to turn them into products that can be delivered in batches, it still relies on the long-term accumulation of suppliers in materials, processing and mass production processes.
Among them, many key manufacturing links are undertaken by Chinese industrial chain enterprises.
Apple reorganizes China's supply chain
The reporter from Jiemian News learned from relevant people in the industrial chain that the inner screen of Apple's first foldable phone iPhone DUO adopts customized nano-texture UTG glass, which can reduce crease display, and the nano-texture glass among them is exclusively developed by Lens Technology.
Lens Technology also mentioned in recent institutional surveys that the company fully supplies core components such as UTG glass, CPI film, UTG glass support plate and 3D glass cover plate for the major customer's foldable phone project.
"Previously, high-end Android foldable screens have been using UTG glass," an analyst who has long tracked Apple's industrial chain told Jiemian News. UTG is more high-end than PI film and can also reduce creases. "Apple has also made an unequal thickness design for UTG glass, the middle folding part is thinner, and both sides maintain strength. The technical content is indeed higher than the previous requirements."
Lens Technology previously mainly supplied front and back cover glass, camera cover plates and metal middle frames of some models for bar iPhones. In the era of foldable screens, the newly added inner screen and technical requirements have further increased its supply scope and the value of a single device.
Below the UTG is a complete set of foldable OLED and support structure. The flexible screen can be bent, which means that it cannot rely on a whole piece of hard glass to keep flat like an ordinary screen. After unfolding the phone, the center of the screen must be supported by the hinge and the support plate together.
The reporter learned from the industrial chain that Lingyi Intelligent Manufacturing supplies precision structural parts of hinges, screen support plates, ultra-thin VC vapor chambers and ultra-thin stainless steel battery shell modules with flanges for iPhone Duo.
Among them, the screen support plate is located under the flexible inner screen. It needs to provide support for the screen when unfolding to prevent the middle area from sagging, and must not prevent the screen from bending according to the set radius when folding.
Below the support plate is the hinge composed of more than 100 parts. The hinge needs to control the opening and closing resistance, determine the bending radius of the screen, and flatten the center of the screen after the phone is fully unfolded. It also needs to take into account light weight, durability, dustproof and waterproof performance in a very small space.
"There are many parts inside the hinge, which correspond to different processes, including stamping, CNC and MIM," the above-mentioned analyst said. Different manufacturers produce shaft covers, transmission parts, support parts and other precision parts respectively, and then the assembly enterprise assembles them into a complete hinge.
Of course, the problems brought by hinges are not limited to their own processing and assembly. It occupies the space in the center of the body, further reducing the layout space for other parts.
In the unfolded state, the body thickness of iPhone Duo is only about 5.2 mm, about 0.4 mm thinner than iPhone Air. The hinge occupies the space in the center of the body, so the battery, main board and heat dissipation system can only be arranged on both sides respectively.
In order to leave more space for the cells, the battery shell needs to be as thin as possible. Lingyi Intelligent Manufacturing uses ultra-thin stainless steel plates to make flat shells through precision stamping or deep drawing, and forms a circle of flanges on the edge for subsequent welding, sealing and assembly.
If it is too thin, it is easy to wrinkle, crack or rebound and deform during stamping; if it is too thick, it will occupy the limited battery space. The dual batteries are distributed on both sides of the body, and the shape and space conditions of the two battery shells are not exactly the same, which puts forward higher requirements for dimensional accuracy and flatness.
The VC vapor plate also needs to be made thinner. It needs to quickly diffuse the heat generated by the operation of the A20 Pro chip without occupying the already tight internal space.
The links that Chinese supply chain enterprises participate in are not limited to glass and structural parts. According to public responses from listed companies, Zhuhai CosMX supplies cells for Apple's foldable phones; Qiangrui Technology participates in the R&D and design, sample making, trial production and verification of relevant testing equipment and precision jigs; Rongqi Technology participates in the VC heat dissipation testing of iPhone Duo.
Pressure, temperature, fitting position, hinge assembly accuracy and tiny differences between different batches of materials may all affect the final result. After years of iteration, ordinary iPhones have relatively mature production lines and process parameters; iPhone Duo is equivalent to re-establishing a complete manufacturing system.
"Without China's supply chain, it is not completely impossible to make it, but it is very difficult to turn it into a consumer-grade product at the current cost and scale," the above-mentioned analyst said.
China's supply chain has moved from low-cost assembly to precision manufacturing. But whether it can further extend to upstream materials, module assembly and co-design will determine the profit space and bargaining power of these enterprises.
Apple may further expand the foldable screen market
Apple is not the first company to launch a foldable screen phone. Samsung launched related products as early as 2019, and many domestic mobile phone manufacturers have entered the market one after another since then. But even after seven years of development, foldable screens have not yet become mass market products.
Omdia data shows that the global shipment of foldable screen phones in 2025 was 18.2 million units, a year-on-year increase of 6%, which is the lowest growth rate in recent years. In the same period, the global shipment of smartphones was about 1.26 billion units. Based on this calculation, the penetration rate of foldable screens is about 1.4%, which is still a niche category.
In the first half of this year, the global shipment of foldable screen phones was 5.1 million units, a year-on-year decrease of 21.6%. Among them, the shipment of vertical foldable models decreased by 47% compared with the first half of 2025, while the shipment of horizontal book-style foldable models was basically flat.
However, after communicating with many people in the industrial chain, the reporter found that many people still have high hopes for Apple's entry into this market. They believe that the significance of Apple is not just adding a new foldable screen brand, but it may further expand the foldable screen market with its global sales volume, developer ecosystem and supply chain influence.
A person who has been engaged in mobile phone retail for a long time and has come into contact with many foldable screen products also told the reporter that he holds a relatively optimistic judgment on the growth of this market.
In his opinion, people's demand for larger display area exists for a long time. The screen of mobile phones has grown from one or two inches in the early stage to nearly 7 inches, but limited by holding feeling and portability, the size of bar phones has approached the upper limit. Holographic display and scroll screens are still difficult to mature in the short term, so foldable screens have become one of the few feasible solutions that take into account large screens and portability in the next three to five years.
"If Apple can expand the user base and drive Samsung and domestic mobile phone manufacturers to continue to invest, the foldable screen market may enter a new round of growth," the person also mentioned.
According to people in the industrial chain, the sales guidance of Apple's first product in 2026 has exceeded 5 million units, which accounts for about a quarter of the total global foldable screen market in 2025.
In addition, Apple can also promote the further development of the foldable screen software ecosystem.
In the early stage, after the foldable screen is unfolded, many applications only stretch the original mobile phone interface horizontally. For applications such as short videos, social media and e-commerce, a larger screen does not bring significantly better user experience.
A retail industry person who uses a domestic foldable screen phone told the reporter that even if the store manager needs to use a large screen to view business reports, the daily time of unfolding the foldable screen is usually less than 10 minutes.
A large number of applications have not re-designed the information layout, split-screen collaboration and interaction methods for foldable screens. Although users have bought a foldable screen phone, they are still using the logic of a bar phone in practice.
As a result, the foldable screen falls into a cycle: the user base is insufficient, and software manufacturers lack the motivation to make special adaptation; without significant improvement in software experience, users can't find a reason to unfold the screen frequently.
Apple may really change this cycle. If iPhone Duo brings millions of new users, the commercial return for developers to adapt to the large-screen interface will increase accordingly. At that time, foldable screens are likely to change from "foldable bar phones" to new products with independent software ecosystem and interaction logic.
Therefore, the first year after Apple's foldable screen is launched will also become a key window to verify this judgment. In the initial stage of the new product launch, supply may fall short of demand due to limited production capacity and novelty-seeking demand, but what really determines whether the product can continue to grow also depends on whether there are obvious changes in the software ecosystem afterwards.
iPhone Duo is only the first generation of Apple's foldable screen product line. The aforementioned analyst told the reporter that with the production capacity ramp-up and the maturity of the software ecosystem, its sales volume may increase to 20 million to 30 million units in the next two or three years. At that time, it may move from a high-priced, small-scale novelty-seeking product into Apple's main product line.
This article is from the WeChat official account "Jiemian News", written by Liang Baoxin and Li Jiaqi, and released with authorization from 36Kr.