While a foldable iPhone presented a new challenge for Apple’s thermal engineering team, they found a creative way to exploit the device’s hinge to their advantage. Here are the details.
The iPhone Duo hinge features a flexible graphite hose
PCMag recently met with Dan Murray, Apple’s vice president of silicon engineering, and Banafsheh Barabadi, the company’s senior manager of thermal product design, to discuss the architecture of the A20 Pro chip.
The new SoC, which powers the iPhone 18 Pro, iPhone 18 Pro Max and iPhone Duo, is Apple’s first iPhone chip built on a 2nm process, following the technology’s debut with the Mac mini’s M6 chip in August.
And although the A20 Pro was designed with the three new iPhones in mind, the iPhone Duo version offers additional features. These include a second display engine to run both displays simultaneously.
From PCMag:
The A20 Pro variant of the iPhone Duo is slightly different. “For iPhone Duo, we added a second display engine to support running the indoor and outdoor displays simultaneously,” says Murray, “and with the increased CPU and GPU performance, we ensure we can deliver a smooth user experience across all displays. For the indoor display, we also added support for placing the FaceTime camera behind the display.”
The report offers a very interesting in-depth look at the A20 Pro’s thermals and the new vapor chamber Apple developed to keep them at bay. This includes what Apple calls “metal-on-foam,” a material that iFixit also looked at in the recent iPhone 18 Pro teardown.
The second pillar is a new material that bridges the gap between the A20 Pro and the vapor chamber. “We call it metal-on-foam,” says Barabadi, and it “essentially creates a direct thermal and mechanical coupling between the SoC and the vapor chamber. It’s very efficient at dissipating heat, meeting the strict mechanical requirements of the system. It took us months of development to get the material properties exactly right to be able to use this material.”
Perhaps the most interesting tidbit in the story is what Apple has done to improve the iPhone Duo’s thermal performance, especially given the challenges of dissipating heat in a device that doubles in thickness when folded.
Extract from the report:
“This was one of the more technical aspects of our design,” says Barabadi. To solve the problem, Apple ran a flexible graphite pipe through the hinge itself to transfer heat between the two halves, increasing the surface area available for heat dissipation. “This part had to be co-designed between our thermal team and the mechanical team. It’s a flexible material that has to survive, as you can imagine, many hinge cycles while maintaining its thermal connectivity, as well as its structural integrity throughout the life cycle of the product.”
PCMagMurray and Barabadi’s interview also discusses the architecture of the A20 Pro, including the benefits of placing DRAM next to the CPU rather than stacking it on top, and you can read it in full here.
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