New report explains how Apple will solve the iPhone Fold’s crease problem

Later this year, according to multiple sources, Apple will finally enter the foldables market with a device called either the iPhone Fold or the iPhone Ultra. And there may be a good reason why the company has waited this long: it wants to get foldables right first time.

One of the biggest issues with folding phones is the visible “crease” which can commonly be seen, or which starts to appear after prolonged use, up the middle of the screen. Fixing this problem is central to Apple’s planning: last summer it was reported that the company intended to use crease-free displays from Samsung, based on laser-drilled metal plates which “distribute and control bending stress.” But while important, this measure alone may not be enough to meet Apple’s exacting standards.

A new report published this week outlines further details of Apple’s plan to combat the crease. According to TrendForce, two elements will be key to the iPhone Fold’s success: ultra-thin glass (UTG), and optically clear adhesive (OCA).

UTG has appeared in smartphone displays before now, but as the analysts note, it serves principally as a protective top layer. Based on Apple patent activity, however, UTG will be promoted to a more structural role in the iPhone Fold. “A variable thickness design combined with chemical strengthening [will allow] the folding area to be locally thinned at the bending axis to improve bendability,” TrendForce predicts. Non-bending areas of the screen will remain thicker for impact resistance.

A more important role, however, will be played by OCA. It isn’t merely a glue to hold things together; rather, the material’s unusual physical properties are perfectly suited to the peculiar demands of a folding device.

“OCA,” the report explains, “now exhibits pronounced viscoelastic properties through optimized modulus design and material composition… An optimized OCA enables dynamic modulation of the panel’s mechanical response. It remains soft during gradual bending to reduce fatigue stress, while under sudden external force, its modulus temporarily increases to provide localized structural support.”

Those without a background in materials science may struggle with some of the terminology, but the gist is that the presence of specifically optimised OCA reduces stress concentration during bending. The report adds that it also helps to fill micro-cracks created through long-term use and thereby prolongs the life of the device.

The iPhone Fold (or iPhone Ultra) is currently expected to launch in September, although some pundits have speculated about potential delays. To keep up with all the latest news and rumors, make sure to bookmark our regularly updated iPhone Fold superguide.