Teardown Points to Central Hinge Support Bar
Since Apple's first foldable, the iPhone Duo, went on sale, reports of the inner screen cracking along the crease have spread across communities in various countries. Repair teardown organization iFixit said after a teardown that the possible key may be hidden in the central metal support bar inside the hinge. Apple told tech media WIRED that the inner screens of a small number of devices have developed issues and is offering affected users free replacements, but did not disclose the number of failures and likewise did not comment on the cause of the breakage.
Gaps Left to Avoid a Hard Crease Create Stressed Edges
iFixit chief technician Shahram Mokhtari said the iPhone Duo's hinge is packed with numerous micro gears, spring modules and metal support plates, with flexible cables also needing to pass from one side of the body to the other through the center. To prevent a dead crease when the screen folds, gaps must be left between parts, creating multiple sharp stressed edges at the junctions. The team also built a 3D hinge model using patents, CT scans and video and compared it with user-reported damage locations, finding that cracks mostly fall at the junction of the cable channel and the central support structure.
If Support Bar Fails to Retract, Pressure Concentrates on One Spot
By design, when the phone is closed the central support bar retracts downward to make room for the bending screen. Mokhtari speculates that if clearances between parts are insufficient, or the bar's movement is jammed and fails to retract fully, the screen will press directly onto the metal bar, concentrating force in an extremely small area. This matches user accounts: most people first saw a black dead spot next to the crease, followed by colored bright lines stretching to the right, while some felt something stuck inside the hinge when opening it and heard a crisp cracking sound with slight force.
Limited Sample, Apple Sticks to Case-by-Case Replacements
Tech channel CuriousHagi captured footage of the screen cracking from the center during folding in a durability test, and later found after disassembly that structural parts connected to the central support bar had suffered fatigue fracture, with the break points roughly overlapping user-reported damage. However, that test involved dust and high-pressure conditions with only a single sample, so it cannot be inferred that all retail units share the same defect, and specific-batch part variation, accumulated assembly tolerances and long-term hinge sticking all remain unruled out. Apple continues to offer case-by-case replacements without launching a recall; if the issue lies in the hinge design itself, whether replacements will fail again awaits further repair data and whether Apple explains the cause.