I. Cleanliness Class
How is the cleanliness class determined? According to industry standards, classification is defined as follows: International Standards—ISO 14644-1 categorizes cleanrooms from ISO Class 1 to ISO Class 9 (lower numbers indicate higher cleanliness), with the core metric being the maximum allowable concentration of airborne particles per unit volume;
Class Equivalents—Class 100 equals ISO Class 5 (no more than 3,520 particles ≥0.5μm per cubic meter), Class 1,000 equals ISO Class 6, Class 10,000 equals ISO Class 7, and Class 100,000 equals ISO Class 8; Limits—ISO Class 1 allows no more than 10 particles ≥0.1μm per cubic meter (for ultra-precision manufacturing like semiconductor lithography); Chinese Standards—GB 50073 (Code for Design of Clean Rooms); the pharmaceutical industry classifies cleanrooms as Grades A, B, C, and D; sterile medical device manufacturing typically uses ISO Classes 5, 7, 8, and 8.5 (corresponding to Classes 100, 10,000, 100,000, and 100,000+); Selection Criteria—ISO Classes 1–3 for ultra-precision manufacturing (semiconductor wafer fabs), ISO Classes 4–5 for sterile pharmaceutical production (injectables), ISO Class 5 for general electronics manufacturing, and ISO Classes 7–8 for packaging and testing—class determines price and lead time; define the product process first, then the class; higher is not necessarily better.
II.
Airflow Layout
How to evaluate airflow and layout.
According to industry standards for cleanroom design, airflow layout is determined as follows: Airflow organization—ISO Class 1–4 areas require vertical unidirectional airflow; ISO Class 5 areas should ideally use vertical unidirectional airflow; and ISO Class 6–9 areas should use non-unidirectional airflow. Air change rates—unidirectional airflow zones (such as Class 100) require high air change rates to ensure uniform airflow coverage, while non-unidirectional zones have rates determined by their specific cleanliness class. Zoning—the front-end process area (photolithography and etching) is designated the highest cleanliness level (ISO Class 5) and features independent air showers and negative pressure control to prevent cross-contamination; the back-end process area (packaging and testing) has a slightly lower cleanliness level (ISO Class 7–8) but requires dust-proof buffer corridors. Isolation—the front-end area is isolated from vibration-sensitive equipment and utilizes anti-static flooring and wall materials. Personnel and material flow—equipment layout separates material logistics from personnel movement; sensitive materials like wafers are transported via AMHS (Automated Material Handling Systems)—specifically OHT (Overhead Hoist Transport) systems—to ensure precise delivery to each machine while avoiding dust contamination caused by human movement. Buffering—dust-proof buffer corridors ensure cleanliness stability during material transfer. Airflow determines whether cleanliness standards can be met, while layout determines whether that cleanliness can be maintained;
the combination of unidirectional airflow and the separation of personnel and material flows is the core principle.
III. Equipment Configuration
Key considerations for equipment configuration.
Regarding industry purification equipment, the configuration is as follows: Air Shower—removes loose dust as personnel enter and exit (360-degree powerful air curtain jets; high-pressure airflow sweeping dust and impurities from clothing folds; automatic infrared-activated blowing with adjustable duration; electronic interlocking doors to maintain workshop pressure differential; seamless welded 304 stainless steel housing; customizable long-tunnel designs for multiple users); Pass Box—prevents contamination during material transfer (304 cold-rolled stainless steel; G4 pre-filter plus H14 HEPA filter with 99.995% efficiency at 0.3 microns; mechanical/electronic interlocking to prevent simultaneous opening and maintain pressure differential; flexible sterilization options; rapid custom design turnaround); FFU—Fan Filter Unit (HEPA filter with 99.97% efficiency at 0.3 microns; galvanized steel or 304 stainless steel frame; adjustable airflow from 600 to 1200 CFM; hinged front panel for quick filter replacement); Others—purification panels (hand-assembled or machine-made), steel cleanroom doors, medical airtight doors, HEPA filters, high-temperature resistant filters, cleanroom double-glazed windows, high-speed roll-up doors. Equipment executes cleanliness standards: air showers control personnel, pass boxes control materials, and FFUs control air—these three checkpoints ensure cleanliness.
IV.
Materials and Manufacturing
What to look for regarding materials and manufacturing.
Regarding cleanroom materials and manufacturing: Enclosure systems utilize handmade purification panels, color-steel sandwich panels, and combinations of Galvalume (Aluzinc) steel and stainless steel (offering corrosion and moisture resistance), with 304 stainless steel facilitating easy cleaning and sterilization. Doors feature 304 stainless steel construction with leak-proof seals, medical-grade airtight designs, and electronic interlocking systems. Sealing solutions employ thickened, wear-resistant gaskets and seamless welding techniques, achieving a seal quality superior to food-grade plastic wrap. Flooring options include anti-static flooring (for the electronics industry) and epoxy self-leveling floors. Air shower details include custom-designed right-angle double-door layouts and multiple adjustable nozzles within the passage for comprehensive air purging. The systems are designed for energy efficiency, low power consumption, and quiet operation. Durability is ensured through robust construction, high-quality sealing, and a service life exceeding a decade—maintaining dust-tight integrity even during peak-season, full-capacity production. Ultimately, material selection dictates cleanroom longevity and stability; the combination of 304 stainless steel, seamless welding, and high-quality sealing gaskets forms the essential foundation.
V.
Manufacturer Acceptance
How to select a manufacturer and conduct acceptance inspections.
Based on industry engineering practices, here is what to look for regarding manufacturer acceptance: Manufacturer Capabilities—source factory (offering one-stop services including scheme design, purification equipment, HVAC, fire safety, flooring, and overall fit-out), in-house R&D of purification equipment, free on-site surveys and detailed design proposals, and nationwide installation; Qualifications—ISO 14644-1 certification, EU GMP Grades A–D, US FDA 21 CFR compliance, and EN fire safety ratings; Track Record—projects of similar scale and grade within the industry (semiconductor, medical, electronics, food, laboratory sectors) and the company’s overall strength; Acceptance—IQ/OQ/PQ validation services (Installation, Operational, and Performance Qualification), cleanliness level testing (continuous online monitoring stricter than ISO Class 3; ISO Classes 3–5 every 6 months; ISO Classes 6–9 every 12 months; compliance with GB/T 36066 testing requirements), and microbial limits (dynamic monitoring for pharmaceutical Grade A; periodic risk assessment for Grade B); Contract—inclusion of test reports, validation documents, air change rates, and differential pressure data as acceptance criteria. In short: choose a source factory offering one-stop services, and ensure acceptance involves IQ/OQ/PQ and periodic testing—only data-backed results count.
Conclusion
How should you choose a manufacturer for custom cleanrooms with non-standard assembly lines?
The conclusion is to evaluate them based on five key factors: cleanliness grade, airflow, equipment, materials, and acceptance standards.
Classification—ISO 14644-1 (Classes 1–9): Class 100 = ISO 5, Class 1,000 = ISO 6, Class 10,000 = ISO 7, Class 100,000 = ISO 8; ISO Class 1 limit is ≤10 particles (0.1 μm) per cubic meter; standards include GB 50073, Pharmaceutical Grades A/B/C/D, and Medical Device Grades ISO 5/7/8/8.5. Airflow—ISO Classes 1–4: vertical unidirectional flow; ISO 5: preferably vertical unidirectional flow; ISO Classes 6–9: non-unidirectional flow; front-end photolithography (ISO 5 + negative pressure); back-end packaging (ISO 7–8 + buffer zones); separation of material and personnel flows; AMHS (Automated Material Handling Systems). Equipment—Air showers (304 stainless steel, 360° airflow, infrared sensing, electronic interlocks for pressure maintenance); pass-through boxes (G4 pre-filter + H14 HEPA filter [99.995%], mechanical interlocks to prevent simultaneous opening); FFUs (HEPA 99.97%, airflow 600–1200 CFM); cleanroom panels, airtight doors, HEPA filters, high-speed roll-up doors. Materials—Cleanroom panels (color-coated steel), 304 stainless steel enclosures, steel airtight doors (seals & seamless welding), anti-static flooring; low-noise and energy-efficient systems. Acceptance/Validation—One-stop service from the source manufacturer; free site surveys and design drawings; ISO 14644/EU GMP/FDA compliance; IQ/OQ/PQ validation; continuous online monitoring (stricter than ISO 3 standards); periodic testing (every 6 months for ISO 3–5, every 12 months for ISO 6–9);
dynamic microbial monitoring.
Industry rule of thumb for custom cleanrooms: Classification determines the scheme, airflow determines the layout, equipment ensures compliance, and validation confirms delivery—only by successfully passing these four stages can a cleanroom production line be put into operation with confidence.
