How Apple Uses the Hinge to Cool the iPhone Duo

After years of rumours, Apple finally launched its first foldable iPhone this year. The iPhone Duo runs on the same iOS 27 operating system as other non-foldable iPhones, but it has been tailored for a dual-screen experience. While the hinge connecting the two screens usually presents an engineering challenge, especially when tackling heat dissipation, Apple appears to have taken an unconventional approach to this problem. Apple executives have reportedly revealed that the iPhone Duo's thermal design leverages a flexible component inside the hinge to help move heat across the foldable.

Apple Using Flexible Graphite Pipe Inside the iPhone Duo

In a conversation with PCMag, Apple Vice President of Silicon Engineering Dan Murray and Senior Manager of Thermal Product Design Banafsheh Barabadi revealed that there is a flexible graphite heat pipe routed through the hinge of the iPhone Duo. This is claimed to help with heat transfer between the two halves.

As per the officials, this approach increases the surface area available for heat dissipation, which, in turn, helps the Cupertino-based tech giant manage temperatures in a foldable design where space is limited.

Barabadi told PCMag that this was one of the most technically challenging aspects of the iPhone Duo's design. The Apple executive said that the graphite component was jointly developed by the company's thermal and mechanical engineering teams. The challenge was to keep the pipe flexible enough to withstand repeated opening and closing of the hinge, while also being able to transfer heat and maintain its structural integrity throughout the iPhone Duo's lifespan.

The new hinge-based solution used in Apple's first foldable is claimed to be part of the broader thermal architecture developed for the new A20 Pro chip. The SoC includes a vapour chamber using a material reportedly called “metal over foam”. Per Barabadi, it creates a direct thermal connection while remaining mechanically compliant. Apple reportedly spent months refining its properties before it was ready for use.

The A20 Pro is also Apple's first mobile platform built using a 2nm process. While it powers the iPhone 18 Pro and iPhone 18 Pro Max, the version powering the iPhone Duo includes some additional capabilities. Murray told PCMag that Apple added a second display engine to support simultaneous operation of the inner and outer screens. Further, it also includes support for the under-display FaceTime camera, alongside CPU and GPU performance improvements.