The iPhone Duo solves a big comfort problem with foldable phones

There has been a lot of excitement surrounding the iPhone Duo since Apple announced it in September 2026. Despite its $1,999 starting price, most people have spent their time focusing on the design and cool new features exclusive to the iPhone Duo. However, there’s one development you might not think about much when looking at the first device in Apple’s foldable lineup, and it’s how Apple appears to have solved a long-standing comfort problem for foldables: heat.

Heat is one of the biggest technical challenges in electronics and is responsible for all kinds of problems and compromises. Heat can cause all sorts of performance issues. This also puts more strain on electrical components and causes them to degrade faster overall.

Foldable devices face this problem even more than a typical smartphone, because their design stacks two sides of potentially hot screens and components against each other, changing the way heat radiates in the process. This includes the iPhone Duo, which doubles in thickness when closed. Banafsheh Barabadi, senior manager of thermal product design at Apple, called it one of the most difficult parts of creating the device. So how did Apple overcome this particular problem? Well, in an interview with PC Magazine, he explained how the company ended up using the Duo’s hinge to help out.

Like the iPhone 18 Pro and iPhone 18 Pro Max, the iPhone Duo relies on a vapor chamber to help draw heat away from its A20 Pro chip. In the case of the iPhone Duo, this thinner vapor chamber sits in the middle of the phone. And since the phone is essentially two pieces glued together with a hinge, Apple had to find a way to distribute that heat so it didn’t build up in one place. The answer came from a graphite pipe in the design, which carries heat through the hinge to the rest of the phone, allowing it to dissipate along the way.

Apple’s thermal and mechanical teams worked together on this part because it must continue to move heat while surviving repeated opening and closing over the life of the device. That’s a lot to ask of a single part, especially one you’re going to bend every time you open your phone.

Apple also claims that all this work helps the iPhone Duo deliver up to 35% better sustained performance than the iPhone 17 Pro, and the company’s engineers said they expect it to perform flawlessly without overheating. Of course, these are still Apple’s claims, and we have yet to see any independent testing of the iPhone Duo’s thermals. So if you’re considering buying one and using it for gaming, you might want to wait until the first reviews come in before spending $1,999 on Apple’s first foldable.