A cleanroom, also known as a clean room, is a highly controlled environment designed to maintain a low level of airborne particles, contaminants, and pollutants. It is crucial for scientific research and industrial processes, particularly in semiconductor manufacturing. Cleanrooms are engineered to prevent the entry of dust, airborne organisms, and vaporized particles, ensuring the integrity of materials and processes inside. Additionally, cleanrooms are used to contain hazardous materials, making them essential in fields such as biology, nuclear work, pharmaceuticals, and virology.

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This article indicates several interesting facts about cleanroom. Let’s find out!

1.The birth of cleanroom

The development of cleanrooms has been a fascinating journey marked by significant milestones and innovations. Here’s a chronological overview of the key developments in cleanroom technology:

1940s-1950s: The concept of cleanrooms begins to emerge in response to the need for contamination control in industries such as aerospace and electronics manufacturing. Early efforts focus on basic cleanliness practices and air filtration.

1960s: The semiconductor industry becomes a driving force in cleanroom development. Companies like IBM and Bell Labs pioneer the use of cleanrooms for the production of integrated circuits, recognizing the critical role of particle control in ensuring product quality and reliability.

1960s-1970s: NASA adopts cleanroom technology for its space programs, using cleanrooms to assemble and test spacecraft. This period sees advancements in cleanroom design, including the development of laminar flow systems for air filtration.

1970s: Cleanrooms gain importance in healthcare settings, particularly in pharmaceutical manufacturing and hospital operating rooms. The focus shifts towards controlling microbial contamination to ensure product safety and patient health.

1980s: The introduction of the U.S. Federal Standard 209E establishes standardized classification of cleanrooms based on the number of particles allowed per cubic foot of air. This standard becomes widely adopted and serves as the basis for cleanroom classifications globally.

1990s: The International Organization for Standardization (ISO) develops the ISO 14644 series of standards, which replace the outdated Federal Standard 209E. These standards provide a global framework for cleanroom design, operation, and monitoring.

2000s-present: Cleanroom technology continues to evolve with advancements in filtration, HVAC systems, and monitoring technology. Modular cleanroom designs become more prevalent, offering greater flexibility and cost-effectiveness for cleanroom construction.

2.There is no completely clean room

Dust is a pervasive element, present even in environments that strive for cleanliness, such as cleanrooms. While these controlled spaces are meticulously designed to minimize dust particles, achieving complete dust-free conditions is nearly impossible. The sources of dust are diverse, spanning natural and man-made origins. They include human hair and skin flakes, street dust carried in by air currents, as well as cosmic dust particles that settle from space.

3.There are different standard and classification of cleanroom.

Cleanrooms are classified into different standardized classes, each tailored to specific needs and applications. These classifications are based on the quantity and size of particles permitted per unit volume of air within the cleanroom. This meticulous categorization ensures that cleanrooms meet the stringent requirements of various industries, including pharmaceuticals, electronics, and biotechnology.

Cleanrooms are also classified according to standards set by various organizations, such as the International Organization for Standardization (ISO) and the United States Federal Standard 209E. The classification is based on the number of particles of a specific size per cubic meter of air. Here are the typical classifications:

ISO Class 1-9: ISO standards classify cleanrooms from ISO 1 (the cleanest) to ISO 9 (the least clean), based on the maximum allowable concentration of particles per cubic meter of air.

Federal Standard 209E: This standard was previously used in the United States and classified cleanrooms from Class 1 (the cleanest) to Class 100,000 (the least clean), based on the number of particles 0.5 microns or larger per cubic foot of air.

ISO 14644-1: This is the current international standard for cleanroom classification, replacing the older ISO 14644-1. It aligns with the ISO standards and provides uniform guidelines for cleanroom classification worldwide.

These classifications are crucial for industries such as pharmaceuticals, electronics, and biotechnology, where maintaining specific levels of cleanliness is essential for product quality and safety.

4.The conditions in cleanrooms are to remain as stable as feasible

Cleanrooms are meticulously maintained to ensure consistency in air cleanliness and other critical parameters, such as pressure, temperature, and humidity. These conditions remain stable regardless of external weather variations. To achieve this, air is continuously exchanged through sophisticated air-handling units, and the air is filtered using high-efficiency particulate air (HEPA) or ultra-low particulate air (ULPA) filters. Access to the cleanroom is restricted to designated entry points equipped with airlocks, which help maintain the desired air quality by preventing contaminants from entering the cleanroom.

5.Humans are the primary source of contamination in cleanrooms

Practical observations and academic studies of cleanrooms indicate that the primary sources of microbial contamination can be categorized into three main groups:

a) Human movement b) Material transfer – both solid materials and liquids c) Air circulation and ventilation

Dr. Tim Sandle (2011, 2022) has extensively researched and outlined this classification of contamination sources in various publications and presentations (refer to the pie chart below). While the exact proportions may vary depending on the specific facility and manufacturing processes, this serves as a general framework.

The majority of microbial contamination in cleanrooms is attributed to human activities, comprising approximately 70% of the total sources. Research and industry surveys consistently show that most microbes found in cleanrooms originate from humans and are typically introduced during gowning procedures. Microbes naturally present on the skin and those exhaled by individuals can be transferred into the cleanroom environment.

Managing particle and microbial contamination from personnel entering cleanrooms is a persistent challenge. The design and operation of gowning areas, as well as the process of donning cleanroom attire, significantly impact the emission of particles and microbes by personnel within the cleanroom.

In essence, reducing the number of individuals entering cleanrooms and minimizing their time inside can be among the most effective strategies for mitigating microbial contamination associated with human activity.

Here are some observations regarding particles:

When a person is stationary, they emit approximately 100,000 particles per minute.

Activities such as standing up or sitting down can generate around 2.5 million particles per minute.

Walking slowly can produce about 5 million particles per minute.

Engaging in rapid movements, such as climbing stairs, can result in the emission of approximately 110 million particles per minute!

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6.Specialized working materials are utilized in cleanrooms

Stringent requirements for garments, working tools and surfaces are required in cleanroom. Cleanroom walls, for example, are typically constructed using sealed sandwich panels to minimize particle emissions. Cleanroom floors are commonly made of seamless, easy-to-clean epoxy resin to reduce particle generation. Furniture in cleanrooms is designed with smooth surfaces to prevent particle buildup.

Cleanroom garments are specialized clothing designed to minimize contamination in cleanroom environments. These garments are worn by personnel working in cleanrooms to prevent the introduction of particles, microbes, and other contaminants into the controlled environment. Here are some key characteristics of cleanroom garments:

Material: Cleanroom garments are typically made from materials that generate low levels of particles and are easy to clean. Common materials include synthetic fibers such as polyester or polypropylene, which are non-shedding and static dissipative.

Design: Cleanroom garments are designed to cover the entire body to minimize skin shedding and particle release. They often include coveralls, hoods, booties, and sometimes masks and gloves.

Closure Systems: Cleanroom garments feature closure systems such as zippers, snaps, or elastic to ensure a secure fit and prevent contamination from entering through gaps.

Seams: Seams in cleanroom garments are typically sewn with high-density stitching and are sometimes sealed to prevent particle release.

Cleanliness Level: Cleanroom garments are classified based on the cleanliness level required for the cleanroom environment. Common classifications include Class 1 to Class 100,000, based on the number of particles allowed per cubic foot of air.

Sterility: In some cleanroom environments, such as those in pharmaceutical or medical device manufacturing, garments may need to be sterilized before use to ensure they do not introduce biological contaminants.

Comfort and Mobility: Despite their protective nature, cleanroom garments are designed to be comfortable to wear and allow for freedom of movement to ensure worker comfort and productivity.

7.Not everyone can work in cleanroom

Not everyone can work in a cleanroom, as it requires specific skills, training, and physical attributes. Here are some factors that determine suitability for working in a cleanroom:

Health Status: Individuals with certain health conditions, such as respiratory issues or allergies, may not be suitable for working in a cleanroom environment.

Physical Fitness: Working in a cleanroom often requires wearing protective gear and performing tasks that may be physically demanding. Individuals should be physically fit to handle these requirements.

Attention to Detail: Cleanroom work requires strict adherence to protocols and procedures to maintain cleanliness and prevent contamination. Individuals should have a strong attention to detail and be able to follow instructions carefully.

Training and Certification: Workers in cleanrooms typically require specific training and certification to understand the principles of contamination control and the proper use of cleanroom equipment and gear.

Comfort with Isolation: Cleanrooms are often isolated from the outside environment, and workers may need to spend long periods in this environment. Individuals should be comfortable with this level of isolation.

Ability to Work in a Team: Cleanroom work often involves working closely with others to maintain cleanliness and prevent contamination. Individuals should be able to work effectively as part of a team.

While not everyone may be suited for working in a cleanroom, those who are can find it to be a rewarding and fulfilling environment, especially in industries where contamination control is critical, such as pharmaceuticals, biotechnology, and electronics.