Apple is hiding a very interesting design secret inside the iPhone Duo's hinge. The thermal engineers in Cupertino came up with an ingenious way to solve any potential cooling problems with the tightly packed foldable.
The iPhone Duo has a cooling pipe inside its hinge
Closeup of the iPhone Duo's hinge. | Image by Apple
In an interview with PCMag, Dan Murray, Apple’s vice president of silicon engineering, and Banafsheh Barabadi, the company’s senior manager of thermal product design, shared some insights about the internal design of the iPhone Duo and the cooling challenges the team had with the new A20 Pro chip.
The powerhouse inside the iPhone 18 Pro, iPhone 18 Pro Max, and iPhone Duo is the first Apple silicon built on a 2 nm node to find its way into the company's smartphones.
This was one of the most technically challenging aspects of our design. This part need[ed] to be co-engineered between our thermal team and the mechanical team. It’s a flexible material that needs to survive, as you can imagine, many hinge cycles while maintaining its thermal connectivity, and also its structural integrity throughout the product life cycle.
- Banafsheh Barabadi, senior manager of thermal product design, Apple
Perhaps the most challenging aspect of this new chip was shoving it inside an ultra-thin device that also folds in half. This required new cooling solutions, and the Apple team delivered.
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The team routed a flexible graphite cooling pipe through the hinge in order to transfer heat between the two halves of the phone. The pipe is engineered to survive hundreds of thousands of folding and unfolding actions on the iPhone Duo.
New vapor chamber with metal over foam material
Apple invented a new material to improve the iPhone Duo cooling. | Image by Apple
The cleverly positioned graphite heat pipe is only one part of the cooling equation. The second is a new material used in the iPhone Duo's vapor chamber. Apple calls it "metal over foam." Basically, it's a heat-transfer material that helps connect the processor and the vapor chamber, much like thermal paste.
We call it metal over foam. Basically creates a direct thermal and mechanically compliant coupling between the SoC and the vapor chamber. It is highly effective in removing the 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.
- Banafsheh Barabadi, senior manager of thermal product design, Apple
According to Banafsheh Barabadi, Apple spent months developing the material and fine-tuning its properties to work as intended inside the iPhone Duo. So, don't expect Apple's foldable to heat up and throttle, at least if we're to believe Apple engineers. Of course, we will stress-test the phone once it arrives on our bench, so stay tuned for some real-world testing.
But the iPhone Duo is not just about novel cooling designs. There's new hardware that practically requires the extra cooling.
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Apple also included a second display engine inside the A20 Pro
The A20 Pro chip features a second display engine to allow the iPhone Duo to run its displays simultaneously. | Image by Apple
If you're wondering why the A20 Pro needs to dissipate so much heat, there's a second display engine built inside the processor. This was needed to allow the iPhone Duo to run both the internal flexible screen and the external cover screen simultaneously.
For iPhone Duo, we added a second display engine to support simultaneous operation of the inner and outer displays, and with the increased CPU and GPU performance, we ensure we can deliver a smooth user experience across the displays. For the inner display, we also added support for placing the FaceTime camera behind the display.
- Dan Murray, vice president of silicon engineering, Apple
Dan Murray also shared an interesting fact about the iPhone Duo's software capabilities. Reportedly, you will be able to make FaceTime calls on the iPhone Duo in an unfolded state, as Apple made sure to make use of the under-display camera for that particular feature.
The company has not officially disclosed the exact megapixel count of the under-display camera, but it's believed to be between 2 MP and 8 MP. Known specs include an f/1.8 aperture, 1080p video recording at 30/60 fps, Center Stage support, and auto image stabilization.
The iPhone Duo is shaping up to be a huge hit
The best iPhone Duo feature seems to be a UI animation. | Image by Apple
Meanwhile, the folding and unfolding animation is so popular that people are adapting it for other devices, including Galaxy Z Fold 8 phones and even MacBooks.
Apple is also making sure not to repeat Android foldables' mistakes on launch day and published guidelines for developers to optimize and prepare their apps and games for the iPhone Duo.
The price of the phone starts at $1,999, which is a bit steep, but in light of the ongoing price hikes tied to the memory crisis, the iPhone Duo starts to look like a good deal. The pre-orders are opening on October 16 and the phone would be released a week later on October 23.
Mariyan, a tech enthusiast with a background in Nuclear Physics and Journalism, brings a unique perspective to PhoneArena. His childhood curiosity for gadgets evolved into a professional passion for technology, leading him to the role of Editor-in-Chief at PCWorld Bulgaria before joining PhoneArena. Mariyan's interests range from mainstream Android and iPhone debates to fringe technologies like graphene batteries and nanotechnology. Off-duty, he enjoys playing his electric guitar, practicing Japanese, and revisiting his love for video games and Haruki Murakami's works.
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