Air Filter Selection for Semiconductor & Biotech Cleanrooms: A Practical Guide
As contamination control becomes more demanding,semiconductor components are becoming increasingly sensitive to contamination and defects. From sand to chip, more than 100 processes are carried out over a month in a factory. In this complex environment, any contamination introduced at any stage can cause irreversible damage to wafers.choosing the right air filters ensures product yield, safety, and compliance.
Fan Filter Unit (FFU)
Industries that are particularly sensitive to environmental contamination, such as semiconductor production, biotechnology, biopharmaceuticals, precision engineering, and surgical operating rooms in hospitals, generally rely on cleanrooms for production. Among them, the semiconductor industry demands especially strict control over indoor temperature, humidity, and cleanliness. Any deviation from required standards can disrupt production processes.
Contaminants in cleanrooms originate both externally and internally, and include dust, airborne microorganisms, suspended particles, and volatile chemical gases.
A Fan Filter Unit (FFU) is a critical component in maintaining a controlled, contaminant-free environment in cleanrooms. Each unit typically includes a fan, motor, and a High-Efficiency Particulate Air (HEPA) or Ultra-Low Penetration Air (ULPA) filter. FFUs play a vital role in removing airborne particles and ensuring a consistent level of cleanliness within controlled spaces.
FFUs are designed to ensure process stability for sensitive components, as even the smallest contaminant can affect product quality and yield. As technological advances increase the need for ultra-clean production environments, FFUs have become indispensable in industries where precision and strict compliance with cleanliness standards are essential.
Air filters function based on several mechanisms: inertial impaction, diffusion, interception, sieving, and adsorption. Different mechanisms are dominant depending on the size of the particles being filtered.
Larger dust particles travel with inertia. When airflow bends around a fiber, particles with higher inertia fail to follow the airstream and collide with the fibers. The larger the particle, the stronger the inertia, and the higher the likelihood of being captured.
Particles smaller than 1μm do not follow airflow patterns but instead exhibit random motion due to collisions with air molecules—this is known as Brownian motion. These particles collide more frequently with filter fibers, increasing capture probability.
Interestingly, particles sized 0.1 to 0.3 microns are the most difficult to remove, making them a benchmark for HEPA filter classification. It is widely believed that 0.3μm particles are the hardest to capture, so HEPA filters are rated based on their efficiency at filtering 0.3μm particles.
In Europe, filters achieving over 85% purification efficiency for 0.3μm particles can be certified as HEPA filters.
Performance Indicators for Air Filters
- Rated airflow: The volume of air used in performance testing.
- Resistance (Pressure Drop): Resistance experienced by airflow passing through the filter.
- Efficiency: The ratio of particles captured by the filter to the total number of particles in unfiltered air.
- Dust holding capacity: The weight of dust a filter can hold under specific test conditions.
Among these, resistance is particularly important. It refers to the pressure difference upstream and downstream of the filter as air passes through. In industry, resistance is typically categorized as initial resistance (before use) and final resistance (when the filter reaches its end of life). Final resistance is generally 2 to 4 times the initial resistance.
Reducing resistance can improve filtration efficiency, extend filter life, and lower operating costs. Methods to reduce resistance include choosing low-resistance filter media, optimizing manufacturing processes, reducing air velocity through the filter, and increasing filtration surface area.
Research shows that increasing the filtration area by 50% can extend filter lifespan by 70–80%. Doubling the area can nearly triple the service life.
How to Choose an Air Filter
Air filters come in a wide range of designs. When selecting a filter for a cleanroom, attention must be paid to filter media, frame materials, and sealing components, based on actual operational requirements.
E-FILT, a leading air filter manufacturer, provides a broad portfolio of primary, medium, and high-efficiency air filters tailored for cleanrooms in advanced manufacturing environments. Filter media options include glass fiber, synthetic fiber (such as PP, PP/PET composites, and PTFE).
General Ventilation Filters
- Primary Filters: Panel, Pleated, G4 Bag
- Medium Efficiency Bag Filter: F5 (White), F6 (Green), F7 (Pink), F8 (Yellow)
Sub-HEPA / HEPA Filters
- Separator-less: Unidirectional, Side/Top Inlet, Pleated, Gel Seal, V-shape
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- Frame: Aluminum, Galvanized Steel, Stainless Steel
- With Separator:Paper Separator Filters,Aluminum Separator Filters
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- Frame: Aluminum, Galvanized Steel, Stainless Steel
- Stainless Steel High-Temperature Air Filter: 150°C, 250°C, 350°C
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At the same time, E-FILT’s strong R&D team offers full customization of air filters for existing or upcoming FFU systems—allowing clients to select any frame material, membrane type, and dimension required for their cleanroom setup.
E-FILT: Precision Filtration, Cleaner Tomorrow
Whether you’re upgrading an existing cleanroom or building a new one from the ground up, choosing the right air filtration solution is critical to ensuring product quality and operational efficiency. At E-FILT, we combine technical expertise with customized manufacturing to deliver filters that meet the strictest industry standards. From semiconductor fabs to biotech labs, our solutions are trusted where precision matters most.
