What hinders the development of foldable smartphones? The bottleneck actually lies not in the flexible display device itself, but largely in the flexible cover plate.


Flexible cover plates must have both repeatable bending, transparency, ultra-thin, and sufficient hardness, and it is not easy to find materials that simultaneously possess these characteristics.

The conventional requirement is to be able to bend more than 200000 times under a curvature of 10mm coating diameter, but this is not a rigid standard.

In theory, glass with a thickness less than 100 microns may meet these characteristics, but there is still a lack of sufficient data support for bending performance.

Manufacturers screened PI, PMMA, PET, PU, and other organic polymer materials. These materials are thin enough to be bent, but they lack sufficient hardness. All manufacturers also need to apply hard coatings on these materials to increase their surface hardness.

Due to the fact that hard coatings are usually made by splashing or evaporation, which requires high process temperatures, PI appears to be the preferred material and has the best high-temperature resistance.

So the problem is, as we all know, the flexibility of hard coatings is generally not enough, so panel manufacturers are considering applying new hard coating materials such as organic silicon composites.