Ultrasonic Spraying of PI Liquid onto LCD Screen

Ultrasonic Spraying of PI Liquid onto LCD Screen – Cheersonic

In the field of display technology, LCD screens are widely used in various scenarios such as consumer electronics, industrial control, and car displays due to their mature technology and stable performance. The production of LCD screens is a precise and complex process system, in which the preparation of orientation films is one of the key links affecting the display effect of the screen. This link requires the use of ultrasonic spraying equipment to achieve precise spraying of PI liquid, combined with specific specifications of substrates, to jointly ensure the core performance of LCD screens.

Ultrasonic spraying equipment, as a high-precision coating equipment, has the core advantage of relying on ultrasonic vibration technology to achieve fine atomization and uniform deposition of liquids. Compared with traditional spraying methods, it uses high-frequency ultrasonic vibration to act on PI liquid (polyimide liquid), causing the liquid to form micrometer sized uniform droplets at the nozzle, with concentrated droplet size distribution, avoiding problems such as droplet aggregation and splashing that are prone to occur in traditional spraying. At the same time, the equipment can accurately control parameters such as vibration frequency, spraying pressure, and nozzle movement speed to evenly cover the substrate surface with PI liquid at a preset thickness. This not only reduces the waste of PI liquid and lowers production costs, but also effectively avoids defects such as pinholes, bubbles, and uneven thickness in the coating, laying the foundation for the subsequent implementation of orientation film function.

In the manufacturing process of LCD screens, PI liquid spraying plays an important role in building the alignment benchmark of liquid crystal molecules. The display principle of LCD screens is to use the orientation changes of liquid crystal molecules under the action of an electric field to control the transmission and obstruction of light, thereby presenting images. The polyimide film (oriented film) formed by PI liquid spraying will have specific micro groove structures on its surface, which can guide liquid crystal molecules to align in a predetermined direction, ensuring consistency and stability in the orientation changes of liquid crystal molecules before and after electrification. If the alignment film coating is uneven or has defects, it can cause disorder in the arrangement of liquid crystal molecules, leading to uneven brightness, residual images, and viewing angle deviations on the screen. Therefore, the quality of PI liquid spraying directly determines the display quality of LCD screens.

The substrate specification adapted to this process is a square substrate with a size of 152mm × 152mm and a thickness of only 0.3mm. The design of this specification fully meets the production needs of small and medium-sized LCD screens. In terms of size, the 152mm × 152mm substrate belongs to the typical small and medium-sized substrate, which can meet the size requirements of display panels in smart wearable devices (such as smart watches, bracelets), car central control screens, industrial control instrument panels and other scenarios. It can also achieve cutting and processing of multiple panels in a single production. Through later cutting and splitting processes, a 152mm × 152mm substrate can be divided into multiple small-sized display panels that are suitable for terminal products, improving production efficiency.

In terms of thickness, the ultra-thin substrate of 0.3mm conforms to the current trend of electronic devices becoming thinner and lighter. With the increasing demand for space occupation and weight control in consumer electronics and industrial equipment, the thickness of LCD screens also needs to be reduced accordingly. As the basic supporting component of LCD screens, the thickness of the substrate directly affects the overall thickness of the screen. A 0.3mm substrate ensures sufficient mechanical strength (able to withstand external forces during processes such as spraying, curing, and cutting, and is not easily bent or broken) while minimizing the overall thickness of the LCD screen, meeting the demand for lightweight design in end products.

In practical process applications, the adaptability of ultrasonic spraying equipment to substrates of this specification requires strict calibration. The equipment first uses a positioning mechanism to accurately fix the 152mm × 152mm substrate on the workbench, ensuring that the substrate does not shift during the spraying process; Subsequently, based on the thin and light characteristics of the 0.3mm substrate, the suction force of the workbench was adjusted – using vacuum suction to firmly fix the substrate with moderate suction force, avoiding substrate deformation caused by excessive suction force or substrate displacement caused by insufficient suction force. During the spraying process, the nozzle of the equipment will move along the preset path on the substrate surface, and the spraying range will be precisely controlled based on the substrate size to ensure that the PI liquid only covers the effective display area of the substrate. At the same time, according to the thickness requirements of the orientation film (usually tens to hundreds of nanometers), the PI liquid coating thickness can be controlled within the error range by adjusting parameters such as spraying frequency and nozzle movement speed.

After the spraying is completed, the substrate will enter the subsequent curing process – by high-temperature baking, the solvent in the PI liquid evaporates, forming a stable polyimide film. Then, through the friction orientation process, micro grooves guiding the arrangement of liquid crystal molecules are machined on the surface of the film. Throughout the entire process, the precise spraying of ultrasonic spraying equipment provides a key guarantee for the high-quality formation of orientation films, while the 152mm × 152mm and 0.3mm thick substrate, with its size and thickness advantages, perfectly adapts to the production needs of small and medium-sized LCD screens. The synergy of the three promotes the stable implementation of LCD display technology in various application scenarios.

About Cheersonic

Cheersonic is the leading developer and manufacturer of ultrasonic coating systems for applying precise, thin film coatings to protect, strengthen or smooth surfaces on parts and components for the microelectronics/electronics, alternative energy, medical and industrial markets, including specialized glass applications in construction and automotive.

Our coating solutions are environmentally-friendly, efficient and highly reliable, and enable dramatic reductions in overspray, savings in raw material, water and energy usage and provide improved process repeatability, transfer efficiency, high uniformity and reduced emissions.

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