A cleanroom is a controlled environment with extremely low levels of pollutants such as dust, microbes, aerosol particles, and chemical vapors. Cleanrooms are used in a variety of industries where it is essential to maintain contamination-free conditions, including semiconductor manufacturing, biotechnology, pharmaceuticals, medical devices, and aerospace.
Cleanrooms provide a tightly controlled space where sensitive processes can take place without risk of environmental contamination. The air supply, temperature, humidity, and pressure are all regulated, and stringent protocols are followed for cleaning and maintenance. Personnel wear protective clothing to minimize introduction of external contaminants.
Cleanrooms are categorized into different classes based on the concentration of particles permitted per volume of air. The lower the particle concentration, the cleaner the space. Critical processes demand the highest levels of cleanliness and are performed in the most stringent cleanroom classes.
ISO Standards Overview
The International Organization for Standardization (ISO), an independent, non-governmental international organization, oversees standards for cleanrooms.
ISO cleanroom standards classify cleanrooms according to the number and size of particles permitted per volume of air. The standards aim to control contamination and enable the manufacture of sterile products.
The ISO publishes worldwide standards via the IEC (International Electrotechnical Commission) and national standards bodies. ISO standards provide guidelines to evaluate a facility’s contamination control.
The ISO cleanroom classification system categorizes cleanrooms using a numeric system denoting the number of 0.1 μm or larger particles permitted per m3 of air. The system ranges from ISO Class 1 (the cleanest) to ISO Class 9 (the least clean).
Higher ISO classes have stricter air cleanliness requirements. For instance, in some cases an ISO Class 5 cleanroom is 100 times cleaner than an ISO Class 7 cleanroom.
What is an ISO Class Cleanroom
ISO class cleanrooms are controlled environments defined by the number of particles per cubic meter of a specified size allowed in the atmosphere. The ISO standard 14644-1 defines cleanroom classifications based on the number of particles larger than 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm and 1 μm permitted per m3 of air. The higher the ISO class number, the more particles of a specified size are permitted within the cleanroom environment. For example, an ISO Class 5 cleanroom allows for up to 352,000 particles ≥ 0.5 μm per cubic meter while an ISO Class 3 cleanroom allows for only 1,000 particles of the same size.
The allowable particulate concentrations, or cleanliness levels, are based on a log scale with steps of 10. Each ISO class allows 10 times more particles than the class below it. This exponential scaling provides cleanliness levels suitable for a wide range of processes with different contamination requirements. The ISO standard establishes a consistent framework for specifying and comparing cleanroom cleanliness around the world.
Primary source: ISO Standard Clean Room Information
ISO Class 3
ISO Class 3 cleanrooms have strict standards for particle limits and air quality. According to the ISO 14644-1 standard, ISO Class 3 cleanrooms must contain no more than 1,000 particles per cubic meter that are 0.5 microns or larger in size (Terra Universal, 2022). This makes them suitable environments for manufacturing and research applications that require a high level of cleanliness.
Some common applications for ISO Class 3 cleanrooms include semiconductor manufacturing, pharmaceutical compounding, and medical device assembly (American Cleanrooms, n.d.). The extremely low particle counts help prevent contamination of sensitive processes and products.
Personnel working in ISO Class 3 cleanrooms are required to wear extensive protective clothing, including heads-to-toe coveralls, hoods, masks, gloves, and booties. This specialized garment system protects the cleanroom environment from particles shed by people. Workers must undergo training on proper gowning procedures before entering an ISO Class 3 space.
ISO Class 5
ISO Class 5 cleanrooms, also known as Class 100 cleanrooms, have a maximum particle count of 100 particles of 0.5μm or larger per cubic foot of air (ISO Class 5 Cleanrooms | Fed-Std 209E …). This makes ISO Class 5 cleanrooms suitable for applications that require a very high level of cleanliness such as semiconductor manufacturing, pharmaceutical production, and biotechnology research (ISO Class 5 Cleanroom Design and Build).
Personnel accessing an ISO Class 5 cleanroom are required to wear full cleanroom attire including hood, mask, suit, gloves, and boots. All garments must be tightly sealed with zippers and arm/leg cuffs taped for maximum isolation. Any exposed skin or hair is strictly prohibited as it can shed particles and compromise the cleanroom environment (What is an ISO-5 Cleanroom Classification?).
Key Differences
ISO Class 3 and ISO Class 5 cleanrooms have some notable differences in terms of particle counts, attire requirements, and common uses. According to the ISO 14644-1 standard, an ISO Class 3 cleanroom must have ≤352,000 particles of ≥0.5 μm per cubic meter of air, while an ISO Class 5 cleanroom has a higher limit of ≤3,520,000 particles of ≥0.5 μm per cubic meter of air (Clean Room Classifications (ISO 8, ISO 7, ISO 6, ISO 5)).
The attire requirements also differ between these two cleanroom classes. ISO Class 3 demands full coveralls, hoods, boots, gloves, and masks. ISO Class 5 only requires hairnets, beard covers, coats, and gloves (Clean Room Classifications & ISO Standards).
In terms of uses, ISO Class 3 cleanrooms are suitable for manufacturing semiconductor, pharmaceutical, and biotech products where ultra-low particle counts are critical. ISO Class 5 cleanrooms have higher particle limits so they tend to be used for manufacturing medical devices, optics, electronics, and food products where slightly higher particle levels are acceptable.
Maintaining ISO Classes
Proper maintenance is critical for keeping ISO Class 3 and Class 5 cleanrooms in compliance. This involves carefully controlling airflow, implementing regular cleaning protocols, and monitoring the environment.
Airflow is one of the most important factors. ISO Class 3 cleanrooms require 90-150 air changes per hour, while ISO Class 5 demands 300-480 air changes per hour. This high degree of airflow ensures constant filtration and minimizes the presence of particles (1).
Frequent cleaning is also essential. Surfaces should be wiped down regularly using ISO Class 5 compatible cleaners. Staff must follow gowning protocols and wear protective garments to minimize contamination. All material brought into the cleanroom needs to be thoroughly cleaned as well (2).
Finally, the environment is continuously monitored. Particle counters track particulate levels to ensure they remain within ISO standards. Pressure gauges verify room pressurization. Any deviations can be quickly identified and addressed (3).
With vigilant maintenance of airflow, cleaning, and monitoring, ISO Class 3 and Class 5 cleanrooms can consistently meet their stringent particle standards.
(1) https://www.pristinecleanbags.com/cleanroom-ultimate-guide/iso-5-cleanrooms/
(2) https://blog.gotopac.com/2018/01/26/cleanroom-cleaning-procedure-contamination-control-iso-14644-1-protocol/
(3) https://www.americancleanrooms.com/what-is-an-iso-5-cleanroom-classification/
Cost Differences
When comparing the costs of ISO Class 3 and Class 5 cleanrooms, Class 3 cleanrooms tend to be more expensive to build and operate. This is largely due to the more stringent particulate filtration and air exchanges required for a Class 3 environment.
According to MeCart Cleanrooms, a modular Class 5 cleanroom can cost $100-$300 per square foot to construct, while a Class 3 modular cleanroom ranges from $300-$1,000 per square foot. The filtration and HVAC systems required for ISO Class 3 add substantially to the overall expense.
Likewise, the energy and maintenance costs to operate a Class 3 cleanroom are higher than Class 5. The powerful fan systems and rigorous cleaning protocols necessary to maintain ISO 3 certification lead to increased operating costs over the lifetime of the facility.
For companies that do not require the ultra-clean manufacturing conditions of an ISO Class 3 cleanroom, building to the Class 5 standard can provide significant cost savings in both construction and ongoing operations.
Selecting the Right Class
There are several key factors to consider when determining the right cleanroom classification for your needs:
The required cleanliness level – This depends on the type of product or process. More sensitive products like pharmaceuticals or electronics require cleaner environments like ISO Class 3 or 5. Less sensitive products may only need ISO Class 7 or 8 (ref: https://www.cleanroomsbyunited.com/resources/cleanrooms).
Type of manufacturing or research – For example, semi-conductor production requires ISO Class 1, while pharmaceutical manufacturing may need ISO Class 5 (ref: https://monmouthscientific.co.uk/cleanrooms-iso-classification-factors/).
Cost considerations – Higher ISO classes require more extensive air filtration and cleaning processes, increasing costs. Determine the cleanliness needed at reasonable expense (ref: https://www.news-medical.net/whitepaper/20230908/How-to-choose-the-ISO-class-of-a-cleanroom.aspx).
Facility constraints – Available space, layout, HVAC capabilities may restrict options. A thorough evaluation is needed.
Future flexibility – Building in higher ISO capabilities, even if not immediately needed, allows for future manufacturing changes.
Conclusion
To summarize the key differences between ISO Class 3 and ISO Class 5 cleanrooms, there are a few main takeaways:
ISO Class 3 cleanrooms have stricter particulate requirements – only allowing 3520 particles per cubic meter (0.5 micron or larger). Meanwhile, ISO Class 5 cleanrooms allow a looser particulate limit of 352,000 per cubic meter. The lower particulate concentration in Class 3 makes it suitable for more sensitive processes.
Class 3 cleanrooms also require more rigorous gowning procedures, air filtration, pressurization, and monitoring to maintain air purity. The extra precautions lead to higher operating costs for Class 3 cleanrooms.
While Class 5 cleanrooms are cheaper and provide “clean enough” environments for many processes, the ultra-low particulate levels of Class 3 are critical for manufacturing computer chips, pharmaceuticals, medical devices, and other highly sensitive products.
When selecting the right cleanroom classification, it’s important to carefully evaluate process requirements. Although Class 3 cleanrooms are significantly more expensive, certain manufacturing processes can only be completed in the most stringent environments.