In modern high-precision manufacturing and research, ISO 5 cleanroom requirements are one of the most important topics for engineers, procurement managers, and project leaders when planning controlled environments. To meet strict process stability, product consistency, and contamination control demands, companies searching for what is a clean room or Class 100 clean room often seek a clear understanding of the ISO 5 classification and its components. This article combines international standards with Wonclean’s industry expertise to provide a systematic analysis of the core requirements and design principles of ISO 5 cleanrooms.

What is a Clean Room?

A cleanroom is a controlled environment that strictly regulates the concentration of airborne particles, microorganisms, and chemical contaminants. Its main objectives include:

• Ensuring process stability
• Maintaining product consistency
• Minimizing scrap and safety risks caused by contamination

Modern cleanrooms are primarily defined according to the ISO 14644 system. ISO 5 is equivalent to the traditional Class 100 clean room, meaning a maximum of 100 particles ≥0.5 μm per cubic foot of air. This level is typically applied in high-demand industries such as semiconductor front-end processing, optical manufacturing, and biotechnology.

Relate：WHAT IS A CLEANROOM: A Comprehensive Guide to Core Concepts and Applications

ISO 5 Cleanroom Requirements: Full Breakdown

Particle Control Standards

ISO 5 cleanrooms have strict limits for particles of different sizes:

• Extremely low allowance for particles ≥0.5 μm
• Concentrations are significantly lower than ISO 6 and ISO 7

Therefore, ISO 5 is commonly used for photolithography, development, and critical processes where even the smallest particles can impact quality

Airflow and Velocity Control

ISO 5 cleanrooms typically employ unidirectional (laminar) airflow design. Key design points include:

• 70–80% of the ceiling must be equipped with FFUs (Fan Filter Units) to maintain stable airflow
• Air velocity must stay within the specified range
• Laminar flow should cover critical areas
• Uniform airflow significantly improves yield, while unstable flow can increase defect rates

Airflow management is one of the core ISO 5 cleanroom requirements.

Filtration Systems: HEPA / ULPA

ISO 5 cleanrooms typically use:

• H14 HEPA or U15–U17 ULPA filters (higher grade)
• Design requirements include:
• Strict sealing
• Filter integrity testing (e.g., PAO test)
• Regular differential pressure monitoring

Filters are the “last line of defense,” and their performance directly affects whether the cleanroom meets its intended cleanliness level.

Environmental Control Requirements

Maintaining ISO 5 stability requires strict control of:

• Temperature: 20–24°C (±1°C) to ensure equipment precision and process stability
• Relative Humidity: 40–55% (±5%) to prevent static buildup and material moisture issues
• Noise & Vibration: <65 dB(A) and vibration acceleration <0.005 g RMS to protect precision equipment and microfabrication
• Electrostatic Discharge (ESD): Surface potential <100 V to prevent damage to sensitive components
• Pressure Differential: Cleanroom pressure is typically 5–15 Pa higher than adjacent areas to prevent contamination ingress

These parameters not only affect comfort but also directly influence yield and stability in microfabrication processes.

Structural Materials and Construction

Materials used in ISO 5 cleanrooms must:

• Be non-shedding and non-dust-accumulating
• Resist cleaning agents
• Meet ESD requirements (for certain industries)

Walls, ceilings, baseboards, and penetrations must have seamless, easy-to-clean construction. Any gaps could become contamination sources.

Key Design Considerations for Class 100 Clean Rooms

Since Class 100 clean room and ISO 5 are equivalent, design principles are identical.

Layout and Workflow

Effective layout reduces contamination backflow and cross-contamination:

• Separation of unidirectional and non-unidirectional areas
• Equipment impact on airflow analysis
• Personnel and material pathway planning
• Buffer and equipment room configuration

These factors directly influence whether the cleanroom can maintain its cleanliness level over time.

HVAC / FFU System Design

ISO 5 / Class 100 clean room HVAC and FFU systems require precise control of:

• Airflow per unit area: 0.8–1.2 m³/s·m² for uniform air distribution
• Air Changes per Hour (ACH): 240–600, meeting particle control requirements
• FFU Static Pressure: 50–150 Pa for uniform airflow and equipment stability
• Thermal Load Management: Local temperature variation ≤ ±1°C to prevent thermal disturbances
• Noise Control: FFU noise <65 dB(A)

A good HVAC design balances energy efficiency, system stability, noise control, and ensures cleanroom air cleanliness and uniform flow.

Intelligent Monitoring Systems

Modern ISO 5 cleanrooms increasingly rely on automation and data monitoring:

• Real-time particle counting
• Pressure differential alarms
• Air velocity monitoring
• Filter life management
• Adaptive temperature and humidity control

These systems reduce manual maintenance and help sustain ISO 5 compliance efficiently.

Industry Applications of ISO 5 Cleanrooms

ISO 5 cleanrooms are widely applied in:

• Semiconductor manufacturing (especially front-end processes)
• Medical device assembly and aseptic packaging
• Precision optics and MEMS
• Advanced material research
• Biotechnology laboratories

All these industries share a high sensitivity to particulate contamination.

Long-Term Maintenance of ISO 5 Level

Operation & Maintenance (O&M)

Key practices include:

• Regular inspection of FFUs and HVAC systems
• Filter integrity testing
• Standardized personnel and material management
• Isolation of processes to prevent cross-contamination

Proper maintenance ensures the cleanroom remains stable long-term, not just compliant in the short term.

Validation and Re-Validation

ISO 5 cleanrooms typically require:

• Particle counting tests
• Air velocity and ACH verification
• Pressure differential and sealing checks
• Annual re-validation

This ensures ongoing compliance with ISO 14644 standards.

Common Misconceptions Between Class 100 and ISO 5

Many in the industry confuse Class 100 clean room and ISO 5, assuming they represent different cleanliness levels. In fact, they are equivalent but defined under different standards.

• Class 100: Defined in the old US Federal Standard FS 209E for semiconductors, PCBs, and optics; allows a maximum of 100 particles ≥0.5 μm per cubic foot of air. FS 209E has been phased out.
• ISO 5: Defined in ISO 14644-1; measures particle counts per cubic meter. Maximum for ≥0.5 μm particles is 3,520 per m³, equivalent to Class 100 when converted.

Understanding this equivalence is crucial for international projects, ensuring compliance with global standards and simplifying verification and certification.

Conclusion

Constructing a high-grade cleanroom that operates stably over the long term requires in-depth understanding and full implementation of ISO 5 cleanroom requirements. From layout, air cleanliness, and filtration to O&M strategies, each element determines whether the cleanroom can truly meet Class 100 clean room standards. Wonclean provides integrated solutions from design, construction, to validation, ensuring cleanrooms not only meet standards but also consistently support production and R&D activities over time.

FAQs About an ISO 5 Cleanroom：

Q: What is the difference between ISO 5 and ISO 7 cleanroom?

A: An ISO 5 cleanroom has much stricter particle limits than ISO 7, allowing fewer airborne particles per cubic meter. ISO 5 is suitable for high-precision manufacturing, while ISO 7 is used for less critical processes.

Q: What is ISO 5 grade equivalent to?

A: ISO 5 roughly corresponds to the former Class 100 cleanroom standard, permitting up to 100 particles ≥0.5 µm per cubic foot of air. It’s commonly required in pharmaceuticals, electronics, and biotech industries.

Q: What is the particle count for ISO 5?

A: The ISO 5 particle count allows a maximum of 3,520 particles ≥0.5 µm per cubic meter of air. Strict monitoring with cleanroom particle counters ensures compliance and product integrity.

Q: What are the microbial limits for ISO Class 5?

A: For ISO 5 cleanrooms, microbial limits are extremely low. Typically, ≤1 CFU/m³ for airborne bacteria, ensuring sterile conditions for sensitive pharmaceutical and medical manufacturing.