The air filtration system is the key to controlling particles in cleanrooms. It mainly consists of primary filters, medium-efficiency filters, and high-efficiency particulate air (HEPA) filters or ultra-low penetration air (ULPA) filters. Primary filters can intercept larger particles in the air, such as dust and hair. Generally, their filtration efficiency for particles with a diameter greater than 5 micrometers can reach more than 80%. Medium-efficiency filters further filter medium-sized particles, and their filtration efficiency for particles with a diameter between 1 and 5 micrometers can reach 70% - 90%. HEPA filters have a filtration efficiency of over 99.97% for particles with a diameter of 0.3 micrometers and above, while ULPA filters can even increase the filtration efficiency for particles with a diameter of 0.12 micrometers and above to over 99.999%. These different levels of filters work together to ensure that the air entering the cleanroom is almost free of particles, providing an extremely pure air environment for the production process.

Reasonable airflow organization also plays an indispensable role in particle control. By carefully designing the positions, shapes, and air volume of supply air outlets and return air inlets, specific airflow patterns can be formed within the cleanroom. Common airflow organization forms include unidirectional flow (laminar flow) and non-unidirectional flow (turbulent flow). Unidirectional flow moves evenly and stably in parallel streamlines, which can quickly and effectively carry particles out of the clean area. It is suitable for areas with extremely high cleanliness requirements, such as the lithography process workshop in chip manufacturing. Non-unidirectional flow makes use of the clean air sent out from the supply air outlets to fully mix with the air in the workshop and reduces the particle concentration through multiple cycles of dilution. It is widely used in workshops with general cleanliness requirements. In addition, facilities such as air curtains and air showers can be set up to form an "air barrier" at the entrance of the workshop, preventing the intrusion of polluted air and particles from the outside. At the same time, they can also effectively remove the particles carried on the surfaces of personnel and materials when they enter or exit.

Electrostatic adsorption technology is an innovative means of particle control. By utilizing the effect of an electrostatic field, particles in the air are charged and then adsorbed by collectors with opposite charges. This technology has a very high capture efficiency for tiny particles, especially sub-micron particles that are difficult to be effectively removed by traditional filtration methods. In some local areas with extremely strict requirements for particles and relatively limited space, such as the sample preparation area of an electron microscope laboratory, electrostatic adsorption devices can be used as auxiliary equipment in combination with traditional air filtration systems to further improve the air purification effect. It not only can remove particles efficiently but also has the advantages of low resistance and low energy consumption, which helps to reduce the operating costs of cleanrooms.

If the surfaces of equipment, walls, floors, etc. in the cleanroom are not smooth and clean enough, they are likely to become secondary pollution sources of particles. Therefore, special treatment and regular cleaning of these surfaces are of vital importance. For example, using materials that are smooth, not easy to accumulate dust, and have anti-static properties to decorate the internal surfaces of the workshop can reduce the adhesion of particles. Meanwhile, strict cleaning regulations should be formulated, and professional cleaning tools and cleaning agents should be used to regularly wipe and vacuum the surfaces of the workshop to ensure that the surfaces always maintain a low particle adhesion state. In some areas with extremely high cleanliness requirements, such as aseptic drug filling workshops, even automated cleaning robots will be used to conduct comprehensive and meticulous cleaning of the workshop during production breaks to minimize the risk of surface particle pollution.

People are one of the biggest pollution sources in cleanrooms. The activities of personnel can generate a large number of particles such as dander, hair, and fibers. Therefore, personnel management is an important part of particle control. Personnel entering the cleanroom must wear clean work clothes, masks, hats, shoe covers, and other protective equipment that meet the requirements. They can only enter after passing through purification facilities such as air showers to remove the particles carried on their surfaces. At the same time, the number of personnel and their activity ranges should be limited to reduce unnecessary movements. Materials are also potential sources of particles. Materials entering the cleanroom must undergo strict cleaning, disinfection, and packaging processes. During transportation and storage, dust-proof and anti-pollution measures should be taken to ensure that no additional particle pollution is introduced when the materials enter the production process.

Particle control technologies in cleanrooms are a comprehensive and systematic project, which requires comprehensive consideration and careful design from multiple aspects such as air filtration, airflow organization, electrostatic adsorption, surface treatment, and personnel and material management. Guangzhou Cleanroom Construction Co., Ltd., relying on its rich experience, advanced technologies, and professional team, can customize the most suitable particle control solutions for customers and create high-quality cleanrooms that meet the needs of different industries, helping enterprises achieve efficient and stable production and operation under strict environmental requirements.