Cleanroom Classification Standards and Corresponding Requirements for the Inkjet Printing Industry

Whether in precision semiconductor manufacturing, cutting-edge biopharmaceutical R&D, high-accuracy optical product fabrication, or health-critical food and beverage production, cleanrooms play an irreplaceable role, quietly supporting the advancement of technology and cleanliness.

Air cleanliness refers to the concentration of airborne particulate matter in a controlled environment. A higher particle concentration indicates lower cleanliness, while a lower concentration indicates higher cleanliness. Cleanliness levels are defined by cleanroom classification standards, which specify the maximum allowable particle concentration (number of particles per cubic meter of air) for a given particle size.

 I. Cleanroom Classification Levels

According to the international standard ISO 14644-1, air cleanliness is classified into ISO Class 1 to ISO Class 9 based on particle concentration.

*(By particle diameter, particles are generally classified as: ultrafine particles < 0.1 μm; conventional particles 0.1–5 μm; coarse particles > 5 μm.)*

* ISO Class 1: ≤ 0.1 particles/m³ with diameter ≥ 0.5 μm

* ISO Class 2: Slightly higher allowable particle concentration than ISO 1, still extremely clean

* ISO Class 3: ≤ 1 particle/m³ with diameter ≥ 0.5 μm

* ISO Class 4: ≤ 10 particles/m³ with diameter ≥ 0.5 μm

* ISO Class 5: ≤ 100 particles/m³ with diameter ≥ 0.5 μm

* ISO Class 6: ≤ 1,000 particles/m³ with diameter ≥ 0.5 μm

* ISO Class 7: ≤ 10,000 particles/m³ with diameter ≥ 0.5 μm

* ISO Class 8: ≤ 100,000 particles/m³ with diameter ≥ 0.5 μm

* ISO Class 9: ≤ 1,000,000 particles/m³ with diameter ≥ 0.5 μm

 II. Specific Environmental Standards for Different Cleanroom Classes

 Class 10 Cleanroom (≈ ISO 4)

Key requirements include:

1. Particle concentration: ≤ 0.5 particles/m³ (≥ 0.5 μm)

2. Humidity: 40–60% RH

3. Temperature: 20–26 °C

4. Pressure: Approximately 101.3 kPa

5. Noise level: ≤ 65 dB

6. Illuminance: 300–500 lux

 Class 100 Cleanroom (≈ ISO 5)

1. Particle concentration:

   * ≥ 0.5 μm: ≤ 0.5 particles/L

   * ≥ 5 μm: ≤ 3,520 particles/L

2. Temperature & humidity: 22 °C ± 2 °C, RH 55% ± 5%

3. Pressure differential: ≥ 5 Pa between adjacent rooms

4. Air exchange rate: ≥ 200 air changes per hour

5. Personnel requirements: Cleanroom garments, footwear, and formal training

 Class 1,000 Cleanroom (≈ ISO 7)

1. Air cleanliness: ≤ 1,000 particles/m³ (≥ 0.5 μm)

2. Temperature & humidity: 20–25 °C, RH 45–65%

3. Air velocity: 0.25–0.45 m/s

4. Entry control: Strict personnel and material protocols

5. Filtration system: HEPA or equivalent filters

6. Materials & equipment: Antistatic, easy-to-clean surfaces

7. Monitoring & maintenance: Regular environmental inspection

 Class 10,000 Cleanroom (≈ ISO 7–8)

1. Particle & microbial limits:

   * ≥ 0.5 μm: ≤ 350,000 particles/m³

   * ≥ 5 μm: ≤ 2,000 particles/m³

   * Airborne microbes: ≤ 100 CFU/m³

   * Settling microbes: ≤ 3 CFU/plate

2. Pressure differential:

   * ≥ 5 Pa between different cleanliness grades

   * ≥ 10 Pa between clean and non-clean areas

3. Temperature & humidity: 18–26 °C, RH 45–65%

4. Noise: ≤ 70 dBA (dynamic), ≤ 60 dBA (static)

5. Illuminance:

   * Production areas ≥ 300 lux

   * Auxiliary areas 200–300 lux

6. Equipment: FFUs, air showers, pass boxes, HEPA filters, clean lighting

 Class 100,000 Cleanroom (≈ ISO 8)

 

1. Air cleanliness:

   * ≥ 0.5 μm: ≤ 350,000 particles/m³

   * ≥ 5 μm: ≤ 20,000 particles/m³

   * Airborne microbes ≤ 500 CFU/m³

   * Settling microbes ≤ 10 CFU/plate

2. Temperature & humidity: 20–26 °C, RH 50–60%

3. Air purification system: HEPA filters with ≥99.9% efficiency

4. Pressure differential: ≥ 5 Pa between adjacent clean areas, ≥ 10 Pa to non-clean areas

5. Construction & materials: Sealed structures, smooth and easy-to-clean surfaces

6. Personnel, equipment, and monitoring management

 Class 1,000,000 Cleanroom (≈ ISO 8)

1. Air cleanliness: ≤ 100,000 particles/m³ (≥ 0.5 μm)

2. Workshop layout: Optimized process flow to avoid cross-contamination

3. Air filtration: HEPA filters selected based on airflow design

4. Air pressure control: Positive or negative pressure as required

5. Floor & wall materials: Antistatic, non-shedding materials

6. Additional purification equipment: Clean benches, clean corridors, clean windows

 III. Application Areas by Cleanroom Grade

1. Semiconductor manufacturing: ISO 1–ISO 3

2. Pharmaceutical manufacturing: ISO 4–ISO 5

3. Food processing: ISO 5–ISO 7

4. Electronic assembly: ISO 6–ISO 8

5. General industrial production: ISO 9

 IV. Measures to Improve Cleanroom Cleanliness

1. Air filtration: Use high-efficiency air filters

2. Environmental control: Manage temperature, humidity, and pressure

3. Personnel control: Cleanroom clothing, masks, and access control

4. Equipment maintenance: Regular cleaning and servicing

5. Process optimization: Reduce friction, adopt dust-free packaging

 V. Cleanroom Requirements for the Inkjet Printing Industry

1. Large-format advertising printing: No cleanroom requirement

2. Books & label printing: No cleanroom requirement

3. Digital textile printing: No cleanroom requirement

4. Ceramic & leather printing: No cleanroom requirement

5. PCB text inkjet printing: Class 100,000 or ISO 8

6. PCB solder mask inkjet coating: Class 100,000 or ISO 8

7. New-energy battery cell insulation coating: Class 10,000 or ISO 7

8. OLED panel inkjet coating: ISO 2

9. Semiconductor chips & electronic component inkjet applications: ISO 2

If you notice any inaccuracies or have additional insights, comments, and discussions are welcome. Thank you!