Cleanroom Contaminants: What Are They and How Can I Avoid Them?

Cleanrooms serve as a controlled environment and are used in various industries that need to maintain low levels of particulates and contaminants throughout their production processes. This environmental contamination control is used to ensure product quality, yield, and compliance with regulatory standards. In this article, we will talk about the most prevalent contaminants in cleanrooms and provide strategies to mitigate their impact.

Understanding Cleanroom Contaminants

Contaminants in cleanrooms refer to particles, microbes, and substances that can compromise the cleanliness of the environment. They are classified based on their sources, including human, airborne, equipment, materials, water, chemicals, and facility design. The effect of these contaminants can and likely will disrupt cleanroom operations, leading to product defects, yield losses, compromised research outcomes and often high financial implications.

Common Sources of Contamination, and How to Avoid Them

Human Sources

Human sources contribute to contamination through the shedding of skin cells, hair, and microorganisms, emphasizing the importance of stringent gowning procedures.

1. Human Skin, Hair, Clothing and Exhalation : Human skin and hair constantly sheds particles, including dead skin cells, loose hairs and even hair products. Our clothing can also carry contaminants that can contaminate surfaces and materials within a cleanroom. Even when we breathe, we are exhaling microscopic droplets and particles, which can carry contaminants into the air. To mitigate this, cleanroom personnel should wear appropriate garments such as coveralls, gloves, hoods, hair nets or caps, shoe covers, and facemarks or respirators suitable for the cleanroom class. Along with this, they should be following a strict gowning procedure with dedicated changing and preparation areas. Additionally, regular cleaning and maintenance of cleanroom garments are essential to prevent the accumulation of contaminants.
2. Inadequate Behavior and Training: Actions such as touching surfaces unnecessarily, eating or drinking in the cleanroom, or failing to follow proper hygiene practices can lead to contamination. This is often caused by a lack of training or awareness among cleanroom personnel regarding contamination control measures. Comprehensive training programs should be implemented to educate employees about cleanroom protocols, proper gowning procedures, and the importance of maintaining cleanliness, along with the regular reinforcement of proper behavior.

Airborne Particles

Airborne particles are probably the most common source of contamination in a cleanroom and can stem from various sources both inside and outside the cleanroom, but can be mitigated through the use of high-efficiency filters like HEPA and ULPA.

Some of the sources that can lead to contimating airborne particles being in the cleanroom are:

Human activities such as walking, talking, and working inside the cleanroom.

Machinery, tools, and processes used within the cleanroom can generate particles through friction, abrasion, or off-gassing of materials.

Raw materials, packaging, cleaning agents, and other supplies brought into the cleanroom may contain particles that can become airborne.

Particles from outdoor air, such as dust, pollen, and pollutants, can infiltrate the cleanroom through ventilation systems, doors, and windows.

How to Avoid Airborne Particle Contamination:

1. Proper Ventilation and Filtration: Implementing effective ventilation systems with high-efficiency particulate air (HEPA) or ultra-low penetration air (ULPA) filters can help remove airborne particles from the cleanroom air. Regular maintenance and check ups on your cleanrooms filters is also a necessary aspect to maintaining cleanliness.
2. Facility Design, Construction and Airflow: Cleanroom design and layout, including with controlled airflow systems, is essential for minimizing contaminants.. Cleanrooms feature restricted access points and specialized garments for personnel to reduce contamination. Material selection focuses on non-porous, smooth surfaces that are easy to clean. Rooms may be segregated based on required cleanliness levels, with equipment strategically placed to minimize airflow disruptions. Controlled airflow systems, including HVAC with HEPA or ULPA filters, ensure a continuous supply of clean air while maintaining pressure differentials to prevent contamination ingress. Airflow directionality, pressure differentials, and air change rates are meticulously managed to carry contaminants away from critical areas and maintain cleanliness standards. Our cleanroom design experts specialize in creating these spaces for your specific needs.

‍Equipment and materials

Equipment and materials can introduce contamination into cleanrooms through several means. Firstly, particles may be shed from surfaces of equipment or materials, such as dust or fibers, especially if they are not properly cleaned or maintained. Secondly, some materials may release volatile organic compounds (VOCs) or gases, contributing to air and surface contamination. Additionally, organic residues on equipment can serve as nutrients for microbial growth, leading to microbial contamination. Improper handling or storage of equipment and materials can also transfer contaminants onto surfaces within the cleanroom.

To prevent contamination, strict cleaning procedures, proper material selection, and handling protocols are implemented in cleanroom environments. Regular monitoring and maintenance further help to minimize contamination risks.

Water and chemicals

Water and chemicals can cause contamination in cleanrooms through various means:

1. Water: Water can introduce contamination through droplets, aerosols, or surface residues. This can occur during cleaning processes or through leaks from plumbing systems. Water can carry particles or dissolved contaminants, and its presence can lead to microbial growth if not properly controlled.
2. Chemicals: Chemicals used in cleaning, processing, or as part of manufacturing processes can introduce contaminants into cleanrooms. Residues from chemicals, vapors, or spills can contaminate surfaces, air, and products within the cleanroom.

To avoid contamination from water and chemicals:

1. Proper Handling: Ensure proper handling and storage of chemicals to prevent spills or leaks. Use appropriate containers and labeling to minimize the risk of cross-contamination.
2. Controlled Processes: Implement controlled processes for the use of water and chemicals within the cleanroom. This includes using purified water systems and precisely dosing chemicals to minimize waste and contamination.
3. Regular Monitoring and Maintenance: Regularly inspect plumbing systems, equipment, and storage areas for leaks or damage that could lead to water or chemical contamination.
4. Cleaning Protocols: Develop and adhere to cleaning protocols using approved cleaning agents and procedures. Ensure that cleaning equipment is properly maintained and that personnel are trained in cleaning techniques to avoid introducing contaminants.
5. Environmental Controls: Maintain appropriate environmental controls such as temperature, humidity, and airflow to minimize the spread of contaminants and inhibit microbial growth.

Static Electric Charge

Static electric charge can cause contamination in a cleanroom trough several mechanisms:

1. Attraction & Repulsion of Particles: Charged surfaces in a cleanroom can attract airborne particles. These particles may settle on surfaces, including critical equipment or products, leading to contamination. This attraction is particularly problematic in environments where particles must be kept to an absolute minimum, such as semiconductor manufacturing or precision optics production. Conversely, static charges can also cause particles to repel from surfaces, leading to their suspension in the air. Suspended particles increase the overall particle count in the cleanroom, potentially exceeding acceptable levels and compromising the cleanliness of the environment. Additionally, static charges can cause particles to adhere more strongly to surfaces than they would in a neutral environment, making them more difficult to remove when cleaning and therefore increasing the risk of contamination buildup.
2. Electrostatic Discharge (ESD): In addition to particle contamination, static charges pose a risk of electrostatic discharge (ESD). ESD events can damage sensitive electronic components and equipment, leading to product defects or malfunctions. These events can be especially problematic in industries such as semiconductor manufacturing, where even small electrical disturbances can have significant consequences.

To mitigate the risks, several strategies can be employed:

1. Humidity Control: Maintaining appropriate levels of humidity in the cleanroom can help dissipate static charges by increasing the conductivity of the air and surfaces. However, care must be taken to balance humidity levels with other cleanliness requirements of the environment.
2. Antistatic Materials: Using antistatic materials for equipment, flooring, and furnishings can help minimize the buildup of static charges. Antistatic materials typically contain additives that enhance conductivity and reduce the accumulation of electrostatic charges.
3. Ionization: Ionization systems can neutralize static charges by emitting ions that neutralize charged surfaces and particles.
4. Grounding: Ensuring proper grounding of equipment and personnel can help dissipate static charges and prevent the buildup of electrostatic potentials. Grounding straps and conductive footwear are commonly used to prevent the accumulation of static charges on individuals.
5. Regular Cleaning and Maintenance: Regular cleaning of surfaces and equipment can help remove any accumulated particles and reduce the potential for contamination due to static charges. Special attention should be paid to areas prone to static buildup, such as electronic components and sensitive surfaces.

Conclusion

Ultimately, there are many factors that can cause contamination in a cleanroom environment. Some of the main ones are human sources, airborne particles, equipment, water and chemicals and static electric charge. There are many resources that can be put to use to keep these contaminants from having a time consuming and costly effect. To speak to one of our cleanroom experts on how to keep your cleanroom “clean”, click here.

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