Ultra-Pure Water (UPW) for TFT-LCD Panel Manufacturing

The front-end Array Process of LCD panel manufacturing primarily consists of four stages: Thin Film, Photolithography (Yellow Light), Etching, and Stripping. In LCD production, over 50% of the processes involve direct contact between the substrate/wafer and Ultra-Pure Water (UPW). Furthermore, more than 80% of the processes require chemical treatments which are closely linked to UPW.

Since UPW comes into direct contact with the workpieces, any impurities in the water will lead to device performance degradation, affecting product functionality and yield rates. Consequently, the quality of Ultra-Pure Water is a decisive factor in the advancement of LCD panel technology.

1. The Critical Importance of UPW

During the LCD panel production cycle, over 50% of the stages involve direct interaction between the substrate and UPW, and more than 80% require chemical processing. Any contamination within these steps can result in product defects, compromising display quality and service life. Therefore, the water quality directly determines the final grade of the LCD panel.

2. Water Quality Standards

Depending on the specific requirements of the LCD panels, UPW must meet various resistivity standards, such as 10 MΩ·cm, 15 MΩ·cm, and 18.25 MΩ·cm. These standards ensure that impurities are reduced to the absolute minimum. As production processes become increasingly sophisticated, modern LCD manufacturing demands even higher water purity to adapt to finer circuit architectures.

3. Preparation & Treatment Technology

The production of UPW typically employs multi-stage water treatment technologies, including Reverse Osmosis (RO), Ion Exchange (IX), UV Sterilization, and Ultrafiltration (UF). The combination of these technologies effectively removes ions, organic matter, and microorganisms, ensuring the water quality meets the stringent standards required for LCD production.

4. Key Influencing Factors

Trace impurities in UPW, such as Silicon (Si), Iron (Fe), and Calcium (Ca), can negatively impact LCD panel performance even at extremely low concentrations. Therefore, continuous monitoring and rigorous control of UPW throughout the production process are essential. Additionally, parameters such as water temperature and pH levels significantly influence water stability and must be strictly regulated.

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• Contamination Control