Optical Bonding

When display packaging is suitable for automation, robots are employed to load production lines. The advantages of robotic loading include consistent precision, increased speed, continuous operation, reduced labor costs, improved safety, and the ability to collect and analyze data for process optimisation. Robots also provide scalability and space efficiency. However, there are significant initial setup and maintenance costs associated with automated packing systems. As technology continues to evolve, robots may be able to handle more tasks currently assigned to humans.

On the other hand, manual loading is used when material packaging is not suitable for automation or when robots' vision systems cannot accurately detect the position and orientation of components due to issues like low color contrast between packaging and products. Human operators are effective in these scenarios, adapting to changing production demands, making decisions based on visual indicators, and offering dexterity that machines might not have. While the initial cost of human labor might be lower than robotic automation, long-term economic factors and the human cost of repetitive automateable tasks should be considered. The choice between robotic and manual loading ultimately depends on specific production requirements.

The soft lamination process involves the precise application of OCA (Optically Clear Adhesive) to the display, a critical step in touchscreen display fabrication. The OCA layer can be laminated onto the display using any of the various appropriate methods to ensure consistent adhesion and reduce defects. Precision is essential, as the OCA must uniformly coat the entire glass surface to maintain optical clarity and avoid bonding imperfections.

Although soft lamination does not use significant pressure or heat, it plays a vital role in expelling air pockets and contaminants, prerequisites for achieving a flawless display.

When individual components arrive at the station, a robot gripper, directed by a vision system, places them into trays. These trays are custom-designed to accommodate the specific shape of the cover glass, ensuring they are positioned accurately for subsequent processes. A 2-axis linear robot equipped with a vacuum gripper handles the lifting of the glass, given the task's straightforward nature. However, if the specifics of the production process require it, such as with some curved displays, a 6-axis robot can be deployed.

Using a robot guided by a vision system, the LCD is picked up and precisely laminated with the cover glass. The hard-to-hard lamination between the LCD and the cover glass ensures direct and precise bonding, resulting in a robust bond. Controlled pressure during the initial lamination joins the layers (cover glass, OCA and LCD), enhancing structural integrity, mechanical protection, and optical quality while reducing defects.

During the bonding process of the LCD display to the cover glass, an autoclave is used to ensure a defect-free bond. The LCD panel and cover glass are placed inside the autoclave. Once sealed, the environment within the autoclave is pressurized. The OCA on the cover glass is then heated, making it more viscous, which allows any entrapped air bubbles to dissipate. Pressure cycling within the autoclave further facilitates the removal of these bubbles.

After this phase, a controlled cooling process is initiated to solidify the bond between the LCD and the cover glass.

UV curing is a pivotal step in the bonding process between cover glass and an LCD panel. It entails the assembly of these components with the UV curable OCA layer in between, followed by exposure to UV light. This exposure activates a chemical reaction within the OCA, causing it to cure and solidify. As a result, the OCA transforms from a liquid or gel state to a hardened, optically clear adhesive, securely bonding the cover glass and LCD panel together. This process ensures a robust, transparent, and bubble-free connection, enhancing the quality and durability of electronic devices with LCD displays.

End-of-line inspection for the LCD-bonded cover glass is a necessary quality control step in the manufacturing process of display production. At this stage, the assembled cover glass and LCD panel, securely bonded by the cured OCA adhesive, are visually inspected in dark enclosed enviroment. Advanced optical inspection systems are employed to assess the assembly's integrity, looking for any defects, bubbles, or misalignments. Additionally, the display's optical clarity and functionality are tested to ensure it meets the specified standards.