Flexible displays are light weight, pliable, non-fragile, and inexpensive, and therefore flexible displays are widely used in different types of electronic products. Flexibility technology thus have become a main development direction for the displays. Currently, flexible displays include organic light-emitting diode (OLED) display, liquid crystal display (LCD), flexible electrophoresis display (EPD), micro LED, etc. Materials and techniques used for manufacturing flexible substrate/cover plate are crucial parts for producing these displays. According to prior art, polyimide (PI) is primarily used as a flexible substrate, because polyimide has excellent properties including chemical stability, radiation resisting ability, heat resisting ability, and dielectric properties.
Although a polymer substrate has lower light transmittance than a glass substrate having the same thickness as the polymer substrate, decreasing thickness of the polymer substrate can mitigate this unfavorable disadvantage. On the other hand, with a polymer substrate being used, reducing light reflecting effect can raise light transmittance, thus increasing brightness.
Conventionally, it is known to manufacture the flexible substrate by adopting a multi-film structure and by optimizing refractive index and film thickness of each film, and this design can achieve decrease in reflectivity and increase in transmittance. Chemical vapor deposition (CVD) or physical vapor deposition (PVD) are generally used to form inorganic materials or organic materials on the baseplate. The anti-reflection coating film formed by this method is anisotropic and microscopically uniform, and has high purity, little residual stress, and excellent pliability. This method is the main one of those for forming the anti-reflection coating film. However, the manufacturing process of this method is much more complicated and requires much higher production cost.
Therefore, the conventional process for manufacturing the flexible substrate, though light transmittance of the flexible substrate is increased, is much more complicated and requires much higher production cost, and does not satisfy requirements of scale-up production.