Apple's iPhone Duo Uses a Graphite Pipe in Its Hinge to Manage Heat

Designing a foldable iPhone requires Apple to rethink more than the display and hinge. The company also needs to manage heat in a device with two halves, multiple screens and powerful hardware packed into a compact body.

Apple's reported solution is an unusual one: a flexible graphite pipe that runs through the iPhone Duo's hinge. The component helps move heat between the two halves of the phone, creating more surface area for heat dissipation without relying entirely on the space available inside each section.

The approach was discussed in an interview with PCMag, which spoke with Dan Murray, Apple's vice president of silicon engineering, and Banafsheh Barabadi, the company's senior manager of thermal product design. Their discussion also revealed how Apple developed the A20 Pro chip's cooling system and adapted it for the company's foldable phone.

How the iPhone Duo's Graphite Hinge Helps With Cooling

A foldable phone presents a different thermal challenge from a conventional smartphone. Its internal components must fit into a body that bends at the hinge, while the available space for moving heat away from the processor remains limited.

According to Apple's engineers, the company addressed this challenge by routing a flexible graphite pipe through the iPhone Duo's hinge. This component transfers heat between the phone's two halves, increasing the surface area available for heat dissipation.

The design required close collaboration between Apple's thermal engineering and mechanical engineering teams. The material had to remain flexible enough to withstand repeated folding while maintaining its ability to conduct heat and preserve its structural integrity.

That makes durability an important part of the solution. A hinge moves every time the phone opens or closes, so a thermal component routed through it must continue working through repeated movement over the device's lifetime.

The A20 Pro Chip Powers Apple's Foldable iPhone

The iPhone Duo reportedly uses a specially adapted version of Apple's A20 Pro processor, which also powers the iPhone 18 Pro and iPhone 18 Pro Max. According to the supplied report, the chip is Apple's first iPhone processor built using a 2nm manufacturing process.

Although the A20 Pro was designed for the new iPhone lineup, the version used in the Duo includes additional capabilities to support its foldable design.

A Second Display Engine for Two Screens

One notable change is the addition of a second display engine. This allows the processor to support the inner and outer displays operating simultaneously.

Apple's Dan Murray explained in the PCMag interview that the chip's increased CPU and GPU performance helps deliver a smooth experience across both screens. The foldable-specific version also supports placing the inner display's FaceTime camera behind the screen.

These changes show how a foldable device can require more than simply adapting an existing processor. Its hardware must account for the way users switch between displays and interact with the device in different configurations.

Apple's Vapor Chamber and Metal-Over-Foam Material

The graphite pipe is only one part of the iPhone Duo's reported cooling system. Apple has also developed a vapor chamber designed to help dissipate heat generated by the A20 Pro chip.

Another component connects the processor to that cooling system. Apple calls this material metal over foam, according to the interview.

Banafsheh Barabadi explained that the material creates a direct thermal connection between the system-on-chip and the vapor chamber while remaining mechanically compliant. In other words, it is designed to transfer heat effectively without compromising the physical requirements of the device.

Developing the material reportedly took months because Apple needed to get its properties right for the phone's design. The component must support efficient heat transfer while accommodating the mechanical constraints of a compact foldable.

Together, the vapor chamber, metal-over-foam interface and graphite pipe form a cooling approach designed around the iPhone Duo's unusual internal layout.

Why Cooling a Foldable iPhone Is More Complicated

In a traditional smartphone, thermal engineers can work within a single rigid body. A foldable adds another challenge because the device changes shape, and the hinge creates a physical boundary between its two halves.

That can make it harder to distribute heat across the device while keeping the internal structure durable. The iPhone Duo's cooling design reportedly addresses this by using the hinge as part of the thermal pathway rather than treating it solely as a mechanical component.

The flexible graphite pipe needs to maintain thermal connectivity through repeated hinge cycles. If its performance or structural integrity deteriorates over time, the cooling system could become less effective.

Apple's engineers therefore had to coordinate the thermal and mechanical design from the outset. This is an example of how foldable phones can require new engineering solutions even when they use familiar materials and established cooling technologies.

What This Means for iPhone Duo Performance

Effective thermal management matters because heat can influence how consistently a processor performs during demanding tasks. When a phone struggles to dissipate heat, it may reduce performance to control temperatures.

Apple's combination of a vapor chamber, a specialized thermal interface and a flexible graphite pipe is intended to help manage that challenge in the iPhone Duo.

However, the design details alone do not establish how well the phone performs during extended gaming, video recording or other demanding workloads. Independent testing would be needed to assess sustained performance, temperatures and the effectiveness of the cooling system in everyday use.

The reported architecture does reveal the level of engineering Apple has put into adapting its processor and thermal design for a foldable form factor.

Managing Your Data When Setting Up a New iPhone

Hardware design is only one part of switching to a new phone. Moving photos, videos, contacts and other important content from an existing device is another practical consideration, especially when upgrading to a different form factor.

A data transfer app such as Smart Transfer can help with compatible file transfers between supported devices. Before moving content, it can also be useful to free up storage by reviewing duplicate files, old downloads and media that no longer needs to remain on the phone. A data organiser app can help users keep important content easier to manage during the transition.

File transfers and device migration are not always the same thing. Moving photos or documents does not necessarily transfer app settings, account information or messaging histories, so those may need separate migration methods.

Apple's Foldable Engineering Goes Beyond the Hinge

The iPhone Duo's reported cooling system highlights how many components must work together to make a foldable phone practical. The processor needs to support two displays, the vapor chamber must remove heat efficiently, and the graphite pipe must remain functional despite repeated movement at the hinge.

Apple's engineers have described the flexible pipe as one of the more technically challenging aspects of the design. Its development required the thermal and mechanical teams to work together to balance heat transfer, flexibility and long-term durability.

The full PCMag interview also explores the A20 Pro's architecture, including the decision to place DRAM beside the processor rather than stack it directly on top.

For now, the reported details offer an interesting look at the engineering behind Apple's foldable approach. Real-world testing will ultimately show how effectively these components manage heat and whether the design delivers consistent performance over time.