The iPhone Duo is arguably the most exciting iPhone Apple has released for a long time, but there are still some secrets that Apple hasn't divulged about its first foldable — one of them has just been revealed in an interview with PCMag.
PCMag spoke to Dan Murray, Apple's vice president of silicon engineering and Banafsheh Barabadi, the company’s senior manager of thermal product design, to discuss the A20 Pro chip. As part of this, the pair confirmed that the foldable comes with some unique hardware to better take advantage of the chip's performance power.
The A20 Pro was specifically designed for all three new iPhones, the iPhone 18 Pro, iPhone 18 Pro Max and iPhone Duo. But because the Duo is foldable, things had to change. One such feature is the addition of a second display engine, which allows for "simultaneous operation of the inner and outer displays." There's also extra support for the under-display camera hidden under the interior screen.
Keeping things cool
The most interesting thing is how Apple handles the issue of heat on the iPhone Duo. We knew there's a vapor chamber in the phone, which is something the likes of the Samsung Galaxy Z Fold 8 lack. But problems arise when you remember that this is a phone that can double in thickness at a moment's notice.
For that reason, Apple also added a "flexible graphite pipe" through the hinge, to help transfer heat between both halves of the iPhone Duo. That effectively doubles the amount of surface area available for heat dissipation.
Apple added a "flexible graphite pipe" through the hinge, to help transfer heat between both halves of the iPhone Duo.
The piece in question was co-engineered with Apple's thermal team, with the express goal of ensuring that a flexible material will be able to survive "many hinge cycles" without compromising its conductivity or structural integrity.
Like the iPhone 18 Pro and Pro Max, the iPhone Duo also features a direct connection between the A20 Pro and vapor chamber, which ensures better heat dissipation. This connection is made with what Apple calls "metal over foam," which offers a direct path for heat to travel from the chip to the vapor chamber. At that point, the heat can be safely dissipated throughout the phone, instead of building up in a single area.
That's another iPhone Duo benefit
It's interesting that Apple has done this, though it isn't that surprising. I previously used a thermal camera to see how hot the Samsung Galaxy Z Fold 8 Ultra got during a graphics benchmarking session, and one of the things I noticed was that the heat was contained within one half of the phone — with very little temperature change across the hinge.
Obviously, that's not good for the Z Fold 8 Ultra. Not only does it not have a vapor chamber to aid in cooling, concentrating the heat to that extent can be very bad for the phone over the long term. Not to mention it's going to have a negative impact on sustained performance. By ensuring heat can easily cross the hinge this way, Apple is making sure that those same problems don't affect the Duo.
We'll know for sure how effective these design choices have been once we've put the iPhone Duo to the test. Expect a full review on Tom's Guide soon and pre-orders for the foldable open this Friday (October 16), ahead of release a week later (October 23).