LCD Cleaning Filtration

Process Overview

In LCD display manufacturing, cleaning processes are involved at multiple critical stages. Glass substrates must be thoroughly cleaned before incoming inspection, prior to ITO conductive film sputtering, and before photoresist coating and other lithography-related steps.

The primary objective of cleaning is to completely remove particles larger than 1 μm, as well as inorganic and organic contaminants, in order to meet the stringent surface cleanliness requirements of advanced display fabrication processes.

During cleaning operations, filtration of cleaning liquids is essential to remove contaminants introduced during circulation, enabling liquid reuse or compliant discharge.

Contamination on glass substrates originates mainly from manufacturing processes as well as handling, packaging, transportation, and storage. Typical contaminants include:

Airborne dust particles
Fibers and paper debris
Mineral oils and grease residues
Inorganic particles such as silicon oxide
Process residues
Water stains and fingerprints

Main Cleaning Technologies

Wet Cleaning Processes

Brush cleaning
High-pressure spray cleaning
Immersion ultrasonic cleaning
Continuous-flow high-frequency ultrasonic cleaning
Chemical spray cleaning
Two-fluid (liquid + gas) cleaning
Ultra-high-pressure micro-particle jet cleaning
Functional water cleaning technologies

Dry Cleaning Processes

UV (Ultraviolet) cleaning
Plasma cleaning

Key Challenges

Contaminants in cleaning liquids negatively affect glass substrate performance
Reduced surface affinity between the glass substrate and deposited materials in subsequent processes
Potential damage to delicate or soft thin-film layers on the glass substrate

Filtration Applications

Final filtration for high-purity water, ultrapure water (UPW), and deionized (DI) water used in LCD cleaning processes

Appropriate terminal filtration ensures consistent water quality, prevents secondary contamination, and supports stable, high-yield LCD manufacturing operations.