What is a Cleanroom?
A cleanroom is a specially designed and configured room that has been constructed to eliminate dust particulates and atmospheric contaminants. They are commonly used for scientific research, pharmaceutical production, and other industries that produce products that can be damaged by unsanitary or polluted conditions.
The classification of a cleanroom is determined by the amount of particulate matter (PM), a descriptor for particles and liquids in the air, it has per cubic meter. The air we breathe has about 35 million particles in a cubic meter with an estimated size of 0.5 μm, micrometers or one millionth of a meter.
Cleanrooms are classified by the International Organization of Standards (ISO) that uses a grading system of ISO 1, for extremely clean, to ISO 9, satisfactorily clean. The determination of the classification is decided by the size and numbers of particles in the room's air.
The United States classification system for cleanrooms was Federal Standard 209E published by the Institute of Environmental Sciences and Technology (IEST) in 1963. The IEST used a classification system that ran from Class 1, an ISO 3 class, to Class 100,000, an ISO 8 classification. Though several countries still use the IEST system, it was formally retired in 2001 as being obsolete.
For many years, scientists, engineers, and designers had attempted to create an uncontaminated atmosphere but failed due to problems with uncontrollable particles and airflow. In 1960, Physicist Willis Whitfield developed a filtration system that led to the development of the modern cleanroom.
Requirements for a Cleanroom
Cleanrooms are used by specialized industries, such as pharmaceutical, biotech, semiconductors, laboratories, microchip producers, and photovoltaic. Any manufacturing process requiring strictly controlled production and product handling will have some form of cleanroom. The nature and delicacy of a product determines the level of cleanroom required.
The requirements for a cleanroom begin with staff protection, who wear protective clothing and accessories to prevent contamination. Those specialized items are made from a synthetic material that is wear and tear resistant and are used only once. Anything that enters the cleanroom has to be specially classified and approved down to the smallest detail.
Cleanrooms do not have any furniture, and all surfaces are free of bolts, nuts, visible joints, or any place that may collect dust particles. Equipment and surfaces are smooth and highly polished usually made of plastic or high grade stainless steel. The design and construction of cleanrooms is minimalistic and uncomplicated.
Lighting for a cleanroom has to provide enough light for a smooth operation and follow strict hygienic requirements. It is very important that lighting not require frequent cleaning and be longevous since interior cleaning of a cleanroom means that it has to be recertified.
The most important feature of cleanrooms is their air circulation system. Air flow comes from the ventilation system that strictly controls air movement. Some designs have air enter from the ceiling and exit through the floor. In certain instances, negative pressure is applied to prevent the escape of contaminants from dangerous materials. The items being handled determine the type and kind of airflow system.
Cleanrooms are very expensive to maintain and construct with an average cost between $100 to $150 per square foot. A ten foot by ten foot cleanroom, about the size of a small bedroom, has a cost of $10,000 to $15,000, which can be lower or higher depending on the air control system and instrumentation.
A more flexible type of cleanroom is the modular version that is adaptable, easy to construct, and can be effortlessly changed and modified. They have all of the benefits of more expensive types and produce the same contaminate free environments but at a lower cost.
During the COVID-19 scare of 2020, cleanrooms were and are an essential part of the treatment process. Since their inception in 1960, cleanrooms have found use in several industries, including some that may seem a bit unexpected. Below is a description of some of the uses of cleanrooms.
Isolation rooms for hospitals
Isolation rooms require negative pressure to prevent contaminates from sneezing, coughing, or breathing from traveling from one room to another. These unique rooms have been designed by the collaboration of healthcare workers and cleanroom engineers. They have an alarm to detect pressure loss, hands free showers and toilets, and no circulating air. They use high efficiency particulate air (HEPA) filters that are designed to remove dust, pollen, mold, bacteria, and any particles that are 0.3 µm.
Semiconductor and microelectronic
The sensitive and delicate nature of electronics manufacturers equipment demands very stringent environmental controls. Any defects or deficiencies in a cleanroom can greatly affect a production run. The cleanrooms for these manufacturers are air tight, have UV filtered light, and control mechanisms for electrostatic charges. Unlike most cleanrooms, ones for the electronics industry are larger and more spacious.
Medical device manufacturing
Medical device cleanrooms are designed to control airborne particulates and microorganisms. Additionally, they have to be checked for their bioburden rate, the number of bacteria living on a surface. The demands and regulations for medical device manufacturers has steadily risen over the last few years. Class III medical devices, ones that are implanted or sustain life, are the most stringently controlled.
The compounding pharmacy business has been growing over the last several years and has had restrictions placed on it due to the chemicals and compounds they produce requiring cleanrooms. The unique nature of a compound pharmacy is their ability to mix, produce, and sell drugs specifically designed to meet a customer’s needs. The nature of the materials they use makes it necessary for them to have an enclosed sanitary environment. Their cleanrooms need to meet the ISO standards of 7 or 8.
Laminar air flow
Most cleanrooms are classified as laminar since all cleanrooms have some form of airflow control. Laminar refers to unidirectional airflow, meaning that air makes a single pass through a room. A common version is where the air enters through the ceiling and exits through outlets in the floor. In other designs, air enters through one wall and leaves through an opposite one, which is called horizontal laminar. HEPA filters are located where the airflow enters the room. For most rooms, the ductwork is made of stainless steel or other non-shedding metal.
This class of cleanroom is used for full scale production operations for precision products. They are unlike mini environments that are designed for the production of one tool or process. Ballrooms are large with complete production operations. The major problem with ballroom designs is their ability to produce a completely contained environment.
Types of Clean Rooms
Cleanroom ceilings are drop ceilings constructed of acoustical panels suspended on a tightly fitted grid and are only available in white. They can be high or low depending on the requirements of the room. The snug fit of the tiles prevents dust, moisture, or contaminates from entering the room.
As with many of the components of a cleanroom, ceiling grids are made of high quality aluminum or stainless steel. When tiles are installed on the gird, they are sealed with a gel or rubber gasket around their edges.
Lighting in a cleanroom tends to be the last consideration of its design. Though the lux level, or level of light intensity, may be one consideration, it is important to construct the lighting such that it does not interfere with the airflow and filtration systems. LED lights are the most practical choice since they have a linear shape and can be surface mounted between HEPA and ULPA filters. If at all possible, roof placement of lighting is the best alternative since it can be cleaned or replaced without disturbing the integrity of the cleanroom.
When producing a cleanroom ceiling, manufacturers use a large sheet of raw material that is cut into uniform shapes and sizes. Sealing material is added last before the tiles are shipped to installers. The cutting and shaping process guarantees that the tiles will fit snugly together.
To have a room classified, it has to meet the standards of the International Organization of Standardization or ISO, which was founded in 1947. The founding purpose of this voluntary organization was to establish international standards covering aspects of scientific research and delicate business practices. Though membership has been voluntary, the standards established by the ISO have become the foundational principles that worldwide organizations adhere to. Over the years, the ISO has created over 20,000 standards for member nations to use as a guide when working with chemicals, volatile materials, and sensitive instruments.
Class 100 Clean Rooms
Class 100 clean rooms are the third highest classification in Federal Standard 209 standards. In order to meet regulations, a Class 100 standard clean room must never exceed 100 particles per cubic foot (the particles being 0.5 microns or larger). As a reference point for just how small 0.5 microns is, the average human hair is approximately 75-100 microns in width.
Due to the standards and regulations that Class 100 clean rooms must adhere to, the types of materials from which they are manufactured are limited. As a result, the panel or wall materials in Class 100 clean rooms are often made of materials including white acrylic, steel or stainless steel, aluminum or polycarbonate. In addition to regulating the materials that the clean rooms are manufactured from, the materials entering the clean rooms are also regulated.
Class 1,000 Clean Rooms
Class 1,000 clean rooms are rooms in which the concentration level of airborne particles is controlled so that they never exceed 1,000 particles per cubic foot. Class 1,000 clean rooms are the second lowest classification in Federal Standard 209 standards. The International Organization for Standardization (ISO) equivalent standard of Class 1,000 clean rooms is ISO 6.
Some of the primary applications that Class 1,000 clean rooms are used for include inspection, patterning and integration tools like non-contract profilometry, flip-chip integration, thin-film deposition and laser micromachining. As a result of these diverse applications, Class 1,000 clean rooms are utilized in industries including pharmaceutical, scientific research, medical, electronics, semiconductor, food processing and industrial manufacturing.
Class 10,000 Clean Rooms
Class 10,000 clean rooms are rooms in which the concentration of airborne particles is never allowed to exceed 10,000 particles per cubic foot. The Class 10,000 designation and all the other airborne cleanliness classes in clean rooms and zones name their classes after the maximum number of particles allowed in the rooms at one time.
The primary function of clean rooms is to continuously filter air so that tiny particles in the air do not damage highly sensitive technologies, and in Class 10,000, the air changes 40-60 times an hour. However, this class is not particularly strict when it comes to limitations and rules regarding cleaning, moving around and clothing, but there are still special procedures for each of these activities that must be followed in order to prevent contamination.
Cleanroom equipment is movable items that are not attached to the walls, floor, or ceiling. They can include shoe cleaners, showers, containment hoods, cabinets, monitoring systems, particle counters, spray guns, flow hoods, pass throughs, and UV disinfection units. Small items such as bottles, dispensers, bags, sheets, disinfectants, gloves, and tape may also be present and must be purchased from a cleanroom supplier.
Below is a short list of some of the equipment that can be found in a cleanroom:
Automatic shoe cleaners:
Automatic shoe cleaners have external and built-in vacuums and may include HEPA filters. They can be self-contained in the cleanroom or pass through chamber or connected to an external collection system. A unique form of shoe cleaner is a UV disinfectant clear that uses a germicidal light to kill organisms on the soles of shoes.
Cleanroom pass throughs:
There are a variety of names for pass throughs that include doors, windows, and chambers. They are an airlock chamber for efficiently transferring materials and parts from a cleanroom. Pass throughs reduce contamination between rooms and minimize cleanroom traffic.
Containment hoods are pressurized units with a single HEPA filter and have hard ducting to an external exhaust system. The fan in the hood pulls air away from the operator across the workspace and through the filter. The powerful fans are adjustable and designed for pharmaceutical compounds, powder weighing, and measuring drug dosages. They are available in sizes ranging from 2 feet to 4 feet.
Airborne particle counters are a crucial part for monitoring, classifying, and diagnosing the source of contaminants in a cleanroom. There are two varieties of particle counters – condensation and optical. Condensation counters measure ultrafine particles that are not recorded by optical counters. Light scattering or optical particle counters are the most common type. They measure the number of particles as the particles pass through a light.
Desiccator cabinets are enclosures that contain nitrogen gas used to prevent reactions between moisture on sensitive material and atmospheric humidity. The term desiccator refers to a container that holds a drying agent to remove moisture.
The items listed are a few of the types of equipment that can be found in a typical cleanroom. There are a huge number of specially designed equipment and supplies for cleaning, disinfecting, and decontaminating cleanrooms that are produced by suppliers around the world.
Cleanroom Construction and Design
Cleanrooms are designed to maintain a consistent airflow in a confined space with uniform velocity to avoid turbulence. This is achieved by a ducting and fan system that is connected to a filter, which is usually a HEPA filter.
An important consideration when constructing a cleanroom is the avoidance of potential electrostatic discharge (ESD), which can damage or contaminate materials. Floors and surfaces are designed to prevent ESD’s by creating a non-turbo electric environment.
As a part of the concern for airflow is the construction of the ventilation and air volume systems that are designed to maintain air quality and pressurization. The ventilation system is constantly exchanging old air with fresh filtered air.
Cleanrooms are maintained at a static pressure higher than atmospheric pressure to prevent wind. The exception to the rule is when a cleanroom is being used for hazardous materials and must have a negative air pressure to keep it sealed and to avoid contaminates from escaping.
As with all of the elements in a cleanroom, temperature and humidity must be constant to provide stable conditions for materials and instruments. Since humidity can damage products and equipment with corrosion or condensation, humidity has to be closely monitored and controlled. Control of the humidity can also assist in eliminating static electricity.
Modular Clean Rooms
Modular cleanrooms are a cost effective solution for small companies or ones seeking a quick method for installing a cleanroom. They come in two varieties – hard or soft walled. Hard walled modular cleanrooms have a rigid construction with walls mounted between posts to increase volume for internal air pressure to help minimize contaminates. Soft walled modular cleanrooms have curtains made of vinyl and can have up to a 24 feet span between columns. They are simple to install and cost effective.
All cleanrooms must meet ISO standards. Permanently constructed cleanrooms can meet the cleanest standards of an ISO classification of 1. Modular models, soft or hard walled, meet ISO standards of 5 to 8 depending on construction.
Portable clean rooms, similar to soft wall modular units, are movable atmospheric and climate control enclosures for conducting research or fabrication. They can easily be assembled or disassembled on site without assistance. The growing need for movable and flexible cleanrooms has created increased demand for them.
Portable clean rooms are movable atmospheric and climate-controlled enclosures used to conduct research, fabrication, and other sensitive operations. They are often modular, and some models can be assembled and disassembled without the assistance of service companies. Portable clean rooms are useful for operations that require a basic measure of control over the environments in which their operations are conducted.
Used Clean Rooms
As clean room technology continues to advance, older clean rooms may be left behind to take advantage of the newer versions. However, used clean rooms can provide much the same functionality as new clean rooms, but may not use the same newer, more advanced technology. When purchasing a used clean room, you are essentially trading the newer, more advanced features of a new clean room for reduced upfront costs.
For many applications that do not require the advanced control features, this trade-off makes perfect sense and is a great cost saving option. On the other hand, it is important to keep in mind that used clean rooms may not have the features you require and may exhibit other issues or problems that come along with prolonged usage.
ISO Cleanroom Standards and Classification
Before global cleanroom classifications and standards were adopted by the International Standards Organization (ISO), the U.S. General Service Administration's standards (known as FS209E) were applied virtually worldwide. However, as the need for international standards grew, the ISO established a technical committee and several working groups to delineate its own set of standards.
FS209E contains six classes, while the ISO 14644-1 classification system adds two cleaner standards and one dirtier standard (see chart below). The "cleanest" cleanroom in FS209E is referred to as Class 1; the "dirtiest" cleanroom is a class 100,000. ISO cleanroom classifications are rated according to how much particulate of specific sizes exist per cubic meter (see second chart). The "cleanest" cleanroom is a class 1 and the "dirtiest" a class 9. ISO class 3 is approximately equal to FS209E class 1, while ISO class 8 approximately equals FS209E class 100,000.
Softwall Clean Rooms
Soft wall clean rooms are enclosures that are atmospheric and climate-controlled, and are used in industries that involve carrying out sensitive testing, fabrication, and research processes, such as biotechnology research, medical testing, and semiconductor fabrication. Soft wall clean rooms differ from hard wall clean room systems in several ways. The walls of soft wall clean rooms can be made from fabric pulled taut by a frame, or translucent plastic strips that hang from a ceiling or other overhead fixture. In addition, they are not stationary once installed. They are much more portable than hard wall clean rooms, which are usually permanently in one place once installed. Some varieties of soft wall clean rooms come in a modular design for easier and quicker disassembly and reassembly.
Everything that enters a cleanroom must meet the ISO standards for the room, which includes bottles, gloves, wipes, bags, swabs, and a wide assortment of things that most of us take for granted. Even documents and manuals used for reference have to meet the requirements before being used.
There are several distributors that specialize in cleanroom supplies. All of them carry a large inventory of solutions designed for controlled environments. The term cleanroom supplies is a very broad encompassing a wide range of sterile sanitary items.
The ISO restrictions make the production, creation, and distribution of cleanroom supplies very restrictive. For a cleanroom to maintain its classification, every part of it has to be in accordance with ISO regulations, including the supplies. One bottle or plastic bag that does not meet regulations can cause the room to be declassified and require reclassification.
Important Cleanroom Considerations
Cleanrooms are classified according to the cleanliness and particle count of the air inside them. They are classified according to their compliance with the quantity and size of particulates. ISO 14644-1 summarizes the classification of air cleanliness for cleanrooms and specifies the required particulate airborne particulate count. Cleanrooms are tested and checked on a regular basis to ensure they are able to maintain their classification.
Over the last few years, ISO 14644-1 has undergone various revisions to simplify and streamline the classification process. Also, with the constant technological advancements in production methods, revisions have had to be made to account for these changes and make classification more applicable to present day conditions.