Trial production of Apple's long-anticipated foldable iPhone, likely called the "iPhone Ultra," has run into a significant engineering hurdle centered on hinge reliability, according to a known leaker.

The leaker known as "Instant Digital" posted on Weibo that the foldable device's hinge is consistently failing to meet Apple's quality control standards under conditions of prolonged, high-frequency opening and closing. The leaker described the mechanical wear issue as one that "must be resolved with absolute perfection; otherwise, progress will simply have to be stalled for the time being."

The hinge has been a key focus of Apple's foldable development for years. Supply chain analyst Ming-Chi Kuo first reported that the device would use Liquid Metal components in the hinge mechanism, with Dongguan EonTec serving as the exclusive supplier of the amorphous alloy. Instant Digital subsequently elaborated that the material, also known as metallic glass, features a disordered atomic structure that is more resistant to bending and deformation than traditional metals, and more durable than titanium alloy. This makes it suitable for a foldable's hinge.

Apple has previously used the material only in small components such as SIM ejector pins, so the ‌iPhone Ultra‌ would mark its first major use in a critical mechanical part. A subsequent report in January corroborated the liquid metal hinge plans, noting that Apple has been exploring the material for over 15 years, tracing back to a 2010 licensing deal with Liquidmetal Technologies.

Screen creasing is a concern that has followed the foldable smartphone category since its inception. Instant Digital says Apple has essentially accepted some degree of crease as inevitable, but that test results have demonstrated the device can maintain a visually crease-free state over the long term. That aligns with previous reporting: leaker "Fixed Focus Digital" reported in February that production orders had been placed with a crease depth under 0.15mm and a crease angle under 2.5 degrees. Apple has reportedly pursued eliminating the crease "regardless of cost," with engineering solutions including a dual-layer ultra-thin glass structure designed to spread mechanical stress across multiple layers, and advances in optically clear adhesive to keep display layers in precise alignment.

A follow-up post from the leaker suggested the hinge difficulties are unlikely to push back the device's expected release window somewhat, noting that there is still ample time remaining. That is broadly consistent with earlier reporting: DigiTimes reported in April that production was running roughly one to two months behind schedule, but that a fall 2026 launch remained on track, with mass production planned to begin in July. Apple is expected to announce the foldable iPhone alongside the iPhone 18 Pro models at its September event, though some reports suggest customer availability could slip as late as December.

In a third post, Instant Digital offered a note on the device's experience, suggesting that despite its larger form factor the foldable feels like an iPhone rather than an iPad when in use. The leaker added that the screen size offers limited practical utility for a stylus, casting doubt on whether Apple Pencil support would be a meaningful feature for the device.

The foldable iPhone is expected to feature a 7.8-inch inner display and a 5.5-inch cover display, with an A20 chip, C2 modem, Touch ID power button, and two rear cameras. Pricing is rumored to sit at around $2,000.