Apple's first foldable iPhone Duo yield rate at 60%, mass production ramping up faces challenges

By Liang Baoxin & Li Jiaqi | Jiemian News

With just over a month until its official release, Apple's first foldable iPhone, the iPhone Duo, has yet to complete its production ramp-up.

Low Yield Rate and Production Bottlenecks

On September 17, Jiemian News learned exclusively from sources close to the Foxconn supply chain that the current yield rate for fully assembled iPhone Duo units at Foxconn is only around 60%, resulting in limited initial production volumes. According to Apple's existing quality standards, it may take six months to a year for the yield rate to reach a mature level.

"The supply chain is now waiting for Apple to decide whether to relax its quality requirements. Only then could mass production be accelerated," the source said. The low yield rate is not entirely due to unresolved technical issues, but rather because this is Apple's first mass production of a foldable phone. Production lines still require repeated adjustments to equipment, processes, and parameters during actual operation. "A production line cannot be perfected with just technology and equipment; it needs to be debugged while running."

Jiemian News also learned from industry sources that, in addition to Foxconn's assembly yield issues, Samsung Display's OLED panels and hinge-related components have also experienced yield problems, delivery delays, and design adjustments. Any delay in upstream components compresses the time available for downstream assembly plants to debug their production lines.

A research note from Mizuho Securities on September 3 also mentioned that hinge specifications and screen crease issues are hindering the mass production progress of Apple's foldable phone. Apple must balance its quality standards to move forward with full-scale production.

Sales Targets and Market Expectations

An industry source told Jiemian News that the global stocking target for the iPhone Duo this year is approximately 6 million to 8 million units. In comparison, a mainstream Pro or Pro Max model typically ships 20 million to 30 million units per product cycle.

"The foldable is a standalone model, and since it won't start shipping until October, sales won't be particularly large," the source said.

A channel source told reporters that Apple's sales guidance for the device exceeds 5 million units.

Hinges and Creases: Key Obstacles to Mass Production

Apple has allowed a longer-than-usual ramp-up period for the iPhone Duo.

On September 10, new Apple CEO John Ternus unveiled the iPhone Duo at the launch event. However, unlike previous new iPhones, it did not go on sale immediately. Apple announced that pre-orders for the iPhone Duo will begin on October 16, with official sales starting on October 23.

Jiemian News found that over the past five years, the average time from launch to pre-order for Apple's flagship fall iPhones was about 3 days, and from launch to sale about 10 days. For the iPhone Duo, these intervals have been extended to 36 days and 43 days, respectively — roughly a month longer than usual.

Jiemian News learned that the delayed launch is primarily due to the delivery schedule of core components such as foldable OLED panels and hinges.

The foldable OLED panels for the iPhone Duo are supplied by Samsung Display. An analyst who has long tracked the Apple supply chain said the panel delivery may be later than previously expected, which will push back subsequent assembly and production line ramp-up.

The hinge design has also undergone adjustments. Jiemian News learned from the supply chain that Apple had tested using liquid metal in some hinge components, but the plan was re-evaluated before mass production.

"Once a component's material or production process is changed, other suppliers need to re-sample, verify, and produce. A new supplier cannot immediately ramp up output," the analyst said.

Even without design changes, foldable screens and hinges are not standard, easy-to-produce components. Compared to traditional bar phones, they introduce new materials, structures, and assembly requirements, making error control in manufacturing much more difficult.

Based on the demo units shown at the launch event, the crease on the iPhone Duo is less noticeable than on most foldable phones on the market. However, it still falls short of Apple's original "perfect" vision.

The crease is not simply a groove on the screen surface; it results from the combined effects of screen materials, hinge structure, and overall assembly. A foldable phone not only adds an inner screen but also a hinge composed of over 100 components. The tolerances between the screen, hinge, and body must be extremely tight; otherwise, the result could be a deeper crease, inconsistent opening/closing resistance, local screen depression, or even reduced lifespan.

According to Apple's disclosed technical solutions and information from the supply chain, Apple has broken down the crease problem into three areas: how the screen material changes, how light reflects, and how the screen folds.

• A special adhesive layer relieves bending stress.
• A nano-textured surface diffuses reflected light to visually reduce the crease.
• The hinge and support structure beneath the screen control the bending trajectory and flatten the screen center when unfolded.

These solutions are designed by Apple, but turning them into mass-producible products relies on suppliers' long-term expertise in materials, processing, and manufacturing.

Several key manufacturing steps are handled by Chinese supply chain companies.

Apple Reorganizes Its Chinese Supply Chain

Jiemian News learned from supply chain sources that the inner screen of the iPhone Duo uses a custom nano-textured UTG (Ultra-Thin Glass) to reduce the visibility of the crease. This nano-textured glass was exclusively developed by Lens Technology.

In a recent institutional survey, Lens Technology also mentioned that it is supplying core components for the client's foldable project, including UTG glass, CPI film, UTG glass support plates, and 3D glass covers.

"High-end Android foldables have already been using UTG glass," an analyst tracking the Apple supply chain told Jiemian News. "UTG is more advanced than PI film and also helps reduce creases. Apple has also adopted a non-uniform thickness design for the UTG glass — thinner in the folding area and thicker on the sides to maintain strength. The technical requirements are indeed higher than before."

Lens Technology previously supplied front and back glass, camera covers, and metal frames for bar-style iPhones. With the foldable era, the addition of the inner screen and higher technical demands have expanded its supply scope and increased per-unit value.

Beneath the UTG glass is the foldable OLED and support structure. A flexible screen can bend, but it also means it cannot rely on a single piece of rigid glass to stay flat. When unfolded, the screen center must be supported by both the hinge and a support plate.

Jiemian News learned from the supply chain that Lingyi iTech (Lingyi Zhizao) supplies the iPhone Duo with hinge precision components, screen support plates, ultra-thin VC vapor chambers, and flanged ultra-thin stainless steel battery case modules.

The screen support plate sits beneath the flexible inner screen. It must support the screen when unfolded to prevent sagging in the center, while not hindering the screen's bending along the designed radius when folded.

Below the support plate is the hinge, composed of over 100 components. The hinge controls opening/closing resistance, determines the screen's bending radius, and flattens the screen center when fully unfolded. It must also be thin, durable, dustproof, and waterproof within a very small space.

"The hinge contains many components, each requiring different processes such as stamping, CNC machining, and MIM (Metal Injection Molding)," the analyst said. Different manufacturers produce shaft covers, transmission parts, support parts, and other precision components, which are then assembled by a main contractor into a complete hinge.

The hinge also poses challenges beyond its own processing and assembly. It occupies space in the center of the device, further limiting the layout of other components.

When unfolded, the iPhone Duo is only about 5.2 mm thick — even thinner than the iPhone Air by about 0.4 mm. With the hinge occupying the center, the battery, motherboard, and cooling system must be arranged on either side.

To leave more room for the battery cells, the battery case must be as thin as possible. Lingyi iTech uses ultra-thin stainless steel sheets, formed into flat shells through precision stamping or deep drawing, with a flange around the edge for welding, sealing, and assembly.

If the material is too thin, it is prone to wrinkling, cracking, or spring-back during stamping; if too thick, it takes up valuable battery space. The dual batteries are located on either side of the device, and the shape and space conditions for each battery case are not identical, placing higher demands on dimensional accuracy and flatness.

The VC vapor chamber also needs to be thinner. It must quickly dissipate heat from the A20 Pro chip without encroaching on the already tight internal space.

Chinese supply chain companies are involved in more than just glass and structural components. According to public disclosures from listed companies:

• Zhuhai CosMX supplies battery cells for the foldable iPhone.
• Qiangrui Technology participates in the R&D, prototyping, and trial production of related testing equipment and precision fixtures.
• Rongqi Technology is involved in VC heat dissipation testing for the iPhone Duo.

Pressure, temperature, lamination position, hinge assembly accuracy, and even minor variations between batches of materials can all affect the final result. While standard iPhones have benefited from years of iteration, making their production lines and process parameters relatively mature, the iPhone Duo essentially requires building an entirely new manufacturing system.

"Without the Chinese supply chain, it wouldn't be impossible to make the product, but it would be very difficult to turn it into a consumer-grade product at the current cost and scale," the analyst said.

The Chinese supply chain has evolved from low-cost assembly to precision manufacturing. However, whether it can continue to move upstream into materials, module assembly, and co-design will determine these companies' profit margins and bargaining power.

Apple Could Further Open Up the Foldable Market

Apple is not the first company to launch a foldable phone. Samsung introduced its first foldable in 2019, followed by several Chinese smartphone makers. Yet, even after seven years of development, foldables remain a niche product.

According to Omdia data, global foldable phone shipments in 2025 reached 18.2 million units, a 6% year-on-year increase — the slowest growth rate in recent years. In comparison, global smartphone shipments totaled approximately 1.26 billion units, meaning foldables account for only about 1.4% of the market.

In the first half of this year, global foldable phone shipments were 5.1 million units, down 21.6% year-on-year. Among these, shipments of clamshell-style foldables fell 47% compared to the first half of 2025, while book-style foldables remained roughly flat.

However, after speaking with multiple industry sources, Jiemian News found that many still have high hopes for Apple's entry into this market. They believe Apple's significance lies not just in adding another foldable brand, but in potentially leveraging its global sales volume, developer ecosystem, and supply chain influence to further expand the foldable market.

A retail industry professional who has long sold mobile phones and handled multiple foldable products expressed a relatively optimistic view of market growth.

In his view, the demand for larger display areas has always existed. Phone screens have grown from a few inches to nearly 7 inches, but due to grip and portability constraints, bar phones have nearly reached their size limit. Holographic displays and rollable screens are still far from maturity, making foldables one of the few viable solutions for combining large screens with portability over the next three to five years.

"If Apple can expand the user base and drive Samsung and domestic phone makers to continue investing, the foldable market could enter a new growth phase," he said.

According to supply chain sources, Apple's sales guidance for its first foldable product in 2026 has already exceeded 5 million units, accounting for about one-quarter of the global foldable market in 2025.

Beyond hardware, Apple could also drive further development of the foldable software ecosystem.

In the early days of foldables, many apps simply stretched the original phone interface horizontally when unfolded. For apps like short video, social media, and e-commerce, a larger screen did not significantly improve the user experience.

A retail industry professional who uses a domestic foldable phone told Jiemian News that even though store managers need a large screen to view business reports, they typically unfold the phone for less than 10 minutes a day.

Many apps have not been redesigned for foldable layouts, split-screen functionality, or new interaction methods. Users may buy a foldable phone but still use it like a bar phone.

This creates a cycle: the user base is too small for software developers to justify dedicated adaptation; without improved software experiences, users have little reason to frequently unfold the screen.

What Apple could truly change is this cycle. If the iPhone Duo brings millions of new users, the commercial incentive for developers to adapt their apps for larger screens will increase. Only then might foldables evolve from "foldable bar phones" into products with their own software ecosystem and interaction logic.

Therefore, the first year after the foldable iPhone's launch will be a critical period for testing this hypothesis. Initial supply may be limited due to production constraints and early adopter demand, but the product's long-term growth will depend on whether the software ecosystem undergoes significant changes.

The iPhone Duo is just the first generation of Apple's foldable product line. The analyst told Jiemian News that as production ramps up and the software ecosystem matures, sales could grow to 20 million to 30 million units over the next two to three years. At that point, it could transition from a high-priced, niche novelty into Apple's mainstream product lineup.