Overview
- Apple engineers told PCMag, and were cited by AppleInsider and 9to5Mac Tuesday, that the Duo uses a flexible graphite pipe routed through the hinge to move heat between the two halves.
- The A20 Pro variant in the Duo uses wafer‑level multichip module (WMCM) packaging that places DRAM beside the processor so heat is spread laterally instead of stacked on top of the chip.
- Apple described a four‑pillar thermal approach for the Duo: direct access from silicon to the cooling system, a new metal‑over‑foam coupling material, a vapor chamber enlarged to roughly three times prior surface area, and a nanotube copper plate on the display.
- The metal‑over‑foam layer took months to tune because it must transfer heat while flexing with the chassis, and the hinge graphite design was co‑engineered with mechanical teams so it survives repeated folds.
- Those changes let Apple support a second display engine and an under‑display FaceTime camera in the Duo while keeping higher CPU and GPU performance, building on earlier vapor‑chamber work used in recent Pro iPhones.