Design and Construction of TFT LCD Cleanroom

Thin-Film Transistor Liquid Crystal Display (TFT-LCD) Factory Facility Requirements:

The design of a TFT-LCD factory shall meet the requirements for an ultra-large cleanroom environment necessary for TFT-LCD production.

The main production processes should be complete and well-supported. The array, color filter, and cell processes should preferably be located within the same factory site.

In addition to complying with the relevant provisions of the current national standard "Design Code for Cleanrooms in Electronic Industry," the principle of separate purification air conditioning systems shall also adhere to the following regulations:

1. Cleanrooms with significantly different baseline temperature and humidity should have separate purification air conditioning systems;

2. Cleanrooms with significantly different allowable fluctuations in temperature and humidity should have separate purification air conditioning systems.

The fresh air for the purification air conditioning system should undergo centralized thermal, humidity, and purification treatment. The installation of fresh air handling units shall comply with the following provisions:

1. Supply fans should adopt variable frequency measures;

2. Air should be treated through three stages of filtration: primary, medium, and high-efficiency filters;

3. Backup fresh air handling units should be installed for array, color filter, and cell factories;

4. Motors and fans in array, color filter, and cell factories should adopt direct drive methods with effective vibration damping measures;

5. The fresh air intake location should be far from exhaust outlets emitting harmful or combustible substances;

6. Humidification should preferably use warm water spray chambers;

7. Good airtightness should be ensured, with an air leakage rate not exceeding 1% under working pressure.

The recirculated air for the purification air conditioning systems in array, color filter, and cell factories should preferably be treated using fan filter units (FFUs) and dry cooling coils. The recirculated air for module and backlight factories should preferably be treated using recirculated air handling units.

The installation of dry cooling coils shall comply with the following provisions:

1. The face velocity should not exceed 2.5 m/s;

2. The air-side resistance should not exceed 40 Pa;

3. Dry cooling coils arranged in the same cleanroom (area) should not have an air-side resistance difference exceeding 10% under working conditions;

4. The supply water temperature for chilled water should be higher than the dew point temperature in the cleanroom (area);

5. Dry cooling coils should be equipped with drainage systems, and non-floor-mounted dry cooling coils should have drain pans.

The installation of fan filter units (FFUs) shall comply with the following provisions:

1. Selection should be based on air cleanliness等级 and supply air volume;

2. DC speed control motors should preferably be used;

3. Units should adopt noise reduction measures; noise reduction devices should not use dust-generating materials and must achieve a combustion performance等级 of Class B;

4. Cleanrooms (areas) with cleanliness等级 of Class 7 to 9 should not use filters made of PTFE filter media;

5. Units should facilitate installation, maintenance, and filter replacement.

When using a purification air conditioning system composed of fresh air handling units + fan filter units (FFUs) + dry cooling coils, the air velocity in various parts of the clean area shall comply with the following provisions:

1. The upper technical plenum should not exceed 4 m/s;

2. The lower technical plenum should not exceed 3 m/s;

3. The return air plenum should not exceed 4 m/s.

Relevant Standards:

GB 50472-2008 Design Code for Cleanrooms in Electronic Industry

GB 51136-2015 Design Code for TFT-LCD Factories

GB 50073-2013 Design Code for Cleanrooms

GB 51110-2015 Code for Construction and Quality Acceptance of Cleanrooms

GB 50019-2015 Design Code for Heating, Ventilation, and Air Conditioning of Industrial Buildings

GB 50243-2016 Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Works

GB 50016—2014 (2018 Edition) Code for Fire Protection Design of Buildings