Super hydrophobic coating technology

Invisible nanostructures are fabricated on the lens surface to achieve high durability and ultra-water-repellency

Super hydrophobic coating for a clear view

In recent years, sensing, driver assistance, and monitoring cameras have become widely used for automated driving. Along with this trend, super hydrophobic coatings to keep a clear view in the rain have become crucial. The ultra-water-repellency of lotus leaves is known to be due to the formation of a rough microstructure on the surface (the “lotus effect”). However, this rough microstructure is not resistant to abrasion. Similarly, the application type of ultra-water-repellent materials faced problems in terms of abrasion resistance. To resolve these issues, we decided to form a rugged nanostructure by etching hard inorganic substances instead of applying a material. Abrasion resistance has been improved significantly by employing a two-tier structure and maintaining strength. This ensures a clear view unaffected by rain droplets.

Technology Overview

Invisible rugged nanostructure are formed on a lens surface by etching SiO2. In general, exposure technology is used to form an etching mask. The product uses a silver self-organizing mask. This has eliminated the exposure processes to each lenses, and made it possible to form a mask even on curved surfaces such as lenses. We design rugged patterns that are hard to break and that retain their ultra-water-repellency by adjusting the depth, width, size, and shape of the rugged nanostructures.

High abrasion resistance has been achieved by the etched two-tier structure.

A water droplet repelled on a coated lens.

Water-repellency is maintained after an abrasion test (2,000 times at 250 g/cm2).

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