Construction procedures of clean rooms and their key points

The core of a cleanroom lies in achieving a closed loop of "pollution source blocking - maintaining cleanliness - full-cycle control" through scientific construction, ultimately reaching environmental control at the micrometer or even nanometer level. Cleanroom construction has extremely high requirements for process standardization, technical accuracy, and detail control. Even a 1mm gap or a 1Pa pressure difference fluctuation can cause the entire workshop to fail to meet standards, directly affecting product quality and production compliance.

I. Pre-construction Preparation: Laying a Solid Foundation to Avoid Later Re-work

1. Early Planning: Precisely Matching Process Requirements, Eliminating "Excessive Cleanliness" or "Insufficient Standards"

The primary task is to clearly define the cleanroom grade and core parameters, and precisely position based on industry needs to avoid blindly pursuing high grades that cause cost waste or insufficient grades that fail to meet production requirements. For example:

Semiconductor Industry: Wafer manufacturing (14nm and below) requires ISO 3≥0.5μm particles≤ 35/m³, while packaging and testing can be relaxed to ISO 6≤35,200/m³;

Pharmaceutical Industry: Aseptic filling areas require GMP A (equivalent to ISO 5,≤3,520/m³), and non-aseptic formulation areas are D (equivalent to ISO 8);

Food Industry: General processing areas are ISO 8; aseptic packaging areas need to reach ISO 7, with microbial counts≤1,000 CFU/m³.

2. On-site Survey: Measured data, adapted to on-site conditions

Building Load-bearing: Cleanroom equipment (air conditioning units, fans,etc.) is heavy. The ground load-bearing capacity needs to be≥500 kg/㎡; otherwise, reinforcement measures are required;

Floor Thickness:≥150 mm. This reduces the vibration transmission during equipment operation, especially in semiconductor workshops, with the vibration speed controlled at≤0.1 μm/s;

Base Surface Conditions: The ground flatness error should be≤3 mm/2m. The walls and ceilings should have no cracks or dust, and the base strength should be≥C25; otherwise, repair treatment is necessary.

II. Core Construction Procedures: Each Step Has "Hard Standards"

The core construction of the cleanroom follows the process of "base treatment→enclosure structure construction→purification system installation→auxiliary system integration". The base treatment is a concealed project and is difficult to rectify once completed. The key points are to ensure "damp-proofing, leveling, and dust removal". The enclosure structure (walls, ceilings, doors and windows) is the "barrier" of the cleanroom, and the core requirement is "sealing tightly, smooth surface, and no dust accumulation dead spots".

• Installation of purification system

The purification system (ductwork, air conditioning units, filters) directly determines core indicators such as cleanliness, temperature, humidity, and pressure difference. During construction, every detail must be precisely controlled. The measured data and key points are as follows:

(1) Installation of ducts

During installation, the horizontal deviation of the ducts should be≤3mm/m, and the vertical deviation should be≤2mm/m. The connection flanges of the ducts are sealed with sealing gaskets, which should be free from damage and no splicing. After installation, a pressure test for the ducts is conducted, with a pressure of≥0.8MPa for 30 minutes without leakage.

(2) Installation of filters

A "three-level filtration" system is adopted. The installation sequence is: primary-efficiency filter→medium-efficiency filter→high-efficiency filter. The installation positions and requirements for different levels of filters are different:

Primary-efficiency filter (G4): installed in the fresh air section, replaced once every 3-6 months; Medium-efficiency filter (F8): installed in the air conditioning box, replaced once every 6-12 months;

High-efficiency filter (H13/H14): installed close to the clean area, replaced once every 1-2 years (replace immediately when the resistance reaches 1.5 times the initial value), and ULPA (H15) is used for ISO 3-4 class areas;

After installation, PAO leak detection must be carried out. The leakage rate should be≤0.01%, otherwise, the filter needs to be reinstalled or replaced.

(3) Installation of air conditioning units

The combined air conditioning box needs to integrate the functions of cooling, heating, humidification, and dehumidification, and is combined with duct-type temperature and humidity sensors (accuracy±0.3℃/±2%RH) to achieve PID automatic regulation, meeting the temperature and humidity requirements of different industries.

2. Auxiliary System Integration

The auxiliary systems include air shower, pass boxes, electrical monitoring, and anti-static systems, which may seem like "supporting roles", but they directly affect the stability and practicality of the cleanroom. The construction points are as follows:

Air Shower: Air velocity≥22m/s, shower time 15-30 seconds, equipped with HEPA filters and ionized air nozzles, ensuring that the surface dust removal of personnel≥99%, after installation, the air velocity needs to be measured, with a deviation of≤10%;

Pass box: Interlock (response time≤0.5s), built-in ultraviolet lamp (illuminance≥70μW/cm²), ultraviolet disinfection for transferred materials for 15 minutes, the interlock function needs to be repeatedly tested to ensure no faults;

Electrical and Monitoring: Lamps use clean LED flat lamps (IP65 protection, illuminance≥500lux), installed flush with the ceiling; set particle counters and differential pressure transmitters, data is uploaded in real time to the central control system.

Suzhou Pharma Machinery Co.,Ltd.

2026/03/02

Tia