Fan Filter Units (FFUs) are the core terminal devices for air purification in modern electronic cleanrooms, such as semiconductor, display panel, and integrated circuit production workshops. They are not just simple filters but integrated functional units that combine fans, high-efficiency/ultra-high-efficiency filters (HEPA/ULPA), casings, flow equalization layers, diffusers, and control devices.
I. What are Fan Filter Units (FFUs)?
Traditional supply air outlets are “passive,” relying on the fan of an external central air conditioning system to provide the power to push filtered air into the room. In contrast, FFUs are “active,” with their own fans that actively draw air from the top static pressure chamber, pass it through the internal HEPA/ULPA filters, and then deliver it into the cleanroom in a uniform, vertical airflow.
Core Components:
1. Fan Section:Typically uses brushless DC EC motors, which are energy-efficient, have stable speed regulation, long life, low heat generation, and low vibration.
2. Filter Section: The core is the HEPA (high-efficiency) or ULPA (ultra-high-efficiency) filter, which filters particles larger than 0.3μm or 0.12μm with an efficiency of up to 99.99% to 99.9995%.
3. Casing and Structure: Usually made of cold-rolled steel with powder coating or stainless steel to ensure structural rigidity, corrosion resistance, and dust-free performance.
4. Flow Equalization Device: Located below the filter, often in the form of perforated plates or damping nets, to ensure uniform airflow velocity (within ±10%) across the outlet surface.
5. Diffuser: Spreads the airflow evenly downward to prevent turbulence.
6. Control System: Can integrate speed controllers, PLCs, DDC controllers, etc., to achieve single or multi-unit control, monitoring operating status, air velocity, pressure difference, etc.
II. Technical Applications and Advantages of FFUs in Electronic Cleanrooms
The electronic manufacturing industry has extremely stringent requirements for the production environment, as even the smallest dust particles can cause a sharp decline in product yield. The application of FFUs perfectly meets these demands.
1. Providing Stable and Uniform Vertical Unidirectional Flow (Laminar Flow)
1.1 Application:In key process areas such as chip manufacturing, photolithography, and packaging, a cluster of FFUs covering the ceiling forms a piston-like uniform airflow from top to bottom.
1.2 **Advantage:** This airflow can quickly and effectively push and carry away particle pollutants generated by equipment and personnel downward, preventing lateral diffusion and cross-contamination, providing the highest level of local protection for products.
2. Achieving High Cleanliness Grades (e.g., ISO 1-5)
2.1 **Application:** ULPA filters have a filtration efficiency of up to 99.9995% for particles larger than 0.1μm, making them the only viable solution to achieve ultra-high cleanliness levels such as ISO 1 (Class 1) or Class 10.
2.2 Advantage: Ensuring that the particle concentration in the air is kept below the limit, meeting the stringent requirements of nanoscale processes.
3. Flexibility and Modular Design
3.1 **Application:** When the workshop layout is adjusted, equipment is updated, or processes are upgraded, FFUs can be easily added, moved, or replaced.
3.2 Advantage: Compared to traditional “fan + large HEPA supply air outlet + complex duct” systems, FFUs eliminate the need for large supply air static pressure chambers and most ducts, speeding up construction, and offering great flexibility for later modifications, reducing initial investment and renovation costs.
4. Energy Conservation
4.1 Application:Through EC motors, the air velocity and volume can be infinitely adjusted according to actual needs (e.g., during commissioning, low-load operation at night).
4.2 Advantage:Reducing the air velocity during non-peak production periods can significantly lower fan energy consumption, with operating costs much lower than traditional constant air volume systems. Additionally, the elimination of most ducts also reduces system resistance and heat/cold loss along the way.
5. High Reliability and Ease of Maintenance
5.1 Application: FFUs usually operate in parallel modules, so the failure of one or several units will not cause the entire clean system to fail.
5.2 Advantage: Maintenance can be carried out on individual FFUs without affecting normal workshop production, with high safety. Intelligent control systems can also monitor the operating status, air velocity, and filter terminal resistance of each FFU in real-time, providing early warnings and enabling predictive maintenance.
6. Reducing Building Height Requirements
6.1 Application: FFUs only require a relatively short technical plenum (return air static pressure chamber) and do not need large supply air static pressure chambers and complex duct space.
6.2 Advantage: Effectively reducing the height of the clean factory building can save a significant amount of construction investment.
III. Application Considerations and Selection Points
When applying FFUs in electronic cleanrooms, the following factors need to be comprehensively considered:
1. Cleanliness Grade Requirements: Determine whether to choose HEPA or ULPA filters and their efficiency based on the cleanliness grade.
2. Air Velocity and Volume Control: Determine the face velocity (usually 0.35-0.55 m/s) according to process requirements and select fans with corresponding air pressure and volume.
3. Noise and Vibration: Electronic workshops are sensitive to micro-vibrations, so it is necessary to choose low-noise, low-vibration EC fan units and take effective vibration reduction measures.
4. Material and Structure: Choose galvanized steel or stainless steel casings based on whether the environment is chemically corrosive; ensure good sealing to prevent leakage.
5. Control System:Choose a group control system to achieve centralized monitoring, grouped air velocity adjustment, fault alarms, and other functions.
6. Energy Consumption Indicators: Pay attention to the unit energy consumption of FFUs (such as power consumption per cubic meter of airflow) and select energy-efficient products.
Summary:
Fan Filter Units (FFUs) have become the standard configuration for modern electronic cleanrooms, especially in the semiconductor and display panel industries with ultra-high cleanliness requirements. Through their modular, flexible, highly reliable, energy-saving, and excellent purification performance, they perfectly meet the almost苛刻的要求 of the electronic manufacturing industry for the production environment, and are indispensable key technical equipment to ensure high product yield, improve production efficiency, and realize intelligent manufacturing. The level of their application directly reflects the advancedness and reliability of the cleanroom design.
Post time: Sep-10-2025