by Richard A. Matthews
TITLE: Cleanrooms and associated controlled environments. Part 1: Classes of Air Cleanliness.
SCOPE: Defines the classification of air cleanliness in cleanrooms and associated controlled environments exclusively in terms of airborne particles in sizes from 0.1 micrometer to 5.0 micrometer.
STATUS: Published as an official ISO Standard May 1, 1999.
This document contains some of the only mandatory criteria called for in these new ISO Cleanroom Standards. All other information provided is for guidance only.
This document defines the new international classes of air cleanliness measured in number of particles per cubic meter in six different particle sizes (see Table 1).
There are nine major classes of air cleanliness, which can be further divided into 1/10th increments from ISO Class 1 to ISO Class 9, thereby providing 81 separate classes for fine tolerance clean space design. For example, ISO Class 7.4 would allow up to 1,760,000 particles 0.5 micrometer and larger per cubic meter. (This would be comparable to a Class 50,000 under US Federal Standard 209E).
Under ISO 14644-1, air cleanliness can be determined in three different occupancy states"as built," "at rest" and "operational."
ISO 14644-1 requires that air cleanliness be reported by ISO class number, by occupancy status and by specific particle size or sizes. Reported data must read as follows:
ISO Class 5 "as built" at 0.2 micron and 0.5 micron.
There are further provisions for defining air cleanliness based upon particles larger than 5.0 micrometers. These are called macroparticles or M descriptors. Macroparticles are necessary for defining relatively dirty clean environments where powders or heavy dusts are present as part of a controlled manufacturing process.
There are also provisions for particles smaller than 0.1 micrometer. These are called ultrafine particles or U descriptors. As certain research and manufacturing processes tend toward nanometer dimensions, U descriptors can be utilized to qualify and quantify clean space.
M descriptors and U descriptors cannot be used to define airborne particle cleanliness classes. However, they may be used independently or in conjunction with specific airborne particle cleanliness classes in Table 1.
ISO Standards by design have normative (mandatory) sections and informative (non-mandatory) sections. It is important to know the difference.
Normative sections specify required or directive information. For example, the classes of air cleanliness are normative. How classes are determined is specifically spelled out by a clearly defined mathematical formula. This is also normative.
The basic document, which includes scope, definitions, classification of air cleanliness and demonstration for compliance, is all normative.
In addition, two of the six annexes in this document are normative. They are:
Annex B: Determination of particle cleanliness classification using a discrete-particle-counting, light scattering instrument.
Annex C: Statistical treatment of particle concentration data.
The other four annexes are informative and are provided for user guidance. They provide a relative graphical illustration of the air cleanliness classes, examples of classification calculations, consideration for counting and sizing both macroparticles and ultrafine particles as well as a procedure for sequential sampling.
TITLE: Cleanrooms and associated controlled environmentsPart 2: Specification for testing and monitoring to prove compliance with ISO 14644-1.
SCOPE: Specifies the requirements for periodic testing of a cleanroom or clean zone to prove its continued compliance with ISO 14644-1 classification of airborne particle cleanliness.
STATUS: Published as an official ISO standard September 15.
ISO 14644-2 draws its strength from ISO 14644-1, which was published in May 1999. ISO 14644-2 spells out the mandatory and non-mandatory tests that must be performed to prove compliance with ISO 14644-1. This short document, only 8 pages long, holds lots of clout.
The three mandatory tests that must be performed to prove compliance with ISO 14644-1 are:
a) classification of air cleanliness
b) pressure difference
c) airflow (either volume or velocity)
Tables 1 and 2 from ISO 14644-2 spell out the mandatory time interval between tests and also reference the proper test methods from ISO-14644-3 "Metrology and Test Methods."
ISO 14644-2 also spells out four owner optional tests that are non-mandatory. However, use of some or all of these tests may be appropriate for evaluating clean space performance. These additional four tests are:
a) installed filter leakage
b) airflow visualization
c) recovery time
d) containment leakage
Table A.1 from ISO 14644-2 spells out the time intervals between these owner optional tests and references the proper test methods from ISO 14644-3.
It is significant to note that if an installation has a continuous or frequent monitoring of airborne particle concentration and air pressure difference, the maximum time intervals expressed in Tables 1 and 2 may be extended, provided that the results of this continuous or frequent monitoring remain within the specified limits.
Generally, ISO 14644-1 and ISO 14644-2 require fewer sample locations for air cleanliness classification than is the case with US Federal Standard 209E, thereby providing cost savings at no sacrifice to air cleanliness quality.
The FDIS version of ISO 14644-2 is significantly different from the DIS version. The time intervals between tests have a new flexibility not available with the DIS version or with US Federal Standard 209E. The monitoring plan option based upon risk assessment allows for user-friendly flexibility, but such a plan must be carefully and thoroughly thought out.
TITLE: Cleanrooms and associated controlled environmentsPart 3: Metrology and Test Methods.
SCOPE: Specifies the metrology and testing methods for characterizing the performance of cleanrooms and clean zones.
STATUS: Currently awaiting ISO issuance of a 5-month ISO DIS vote by all the nations of ISO.
ISO 14644-3 places emphasis on the 14 recommended tests used to characterize cleanrooms and clean zones. These tests are:
1) airborne particle count for classification
2) airborne particle count for ultrafine particles
3) airborne particle count for macroparticles
5) air pressure difference
6) installed filter system leakage
7) flow visualization
8) air flow direction
11) electrostatic and ion generator
12) particle deposition
14) containment leak
As identified in ISO 14644-1 and ISO 14644-2, some of these tests are mandatory and most are voluntary. The key controlling factor is the quality level the cleanroom owner desires and what measurements are necessary to help achieve that level.
The overall emphasis of all these tests and their metrology is performance. We build and operate clean space to specific performance criteria in order to achieve a quality standard determined by end-user needs.
ISO 14644-3 does not specifically address measurements on products or processes in cleanrooms. Rather it covers the cleanroom performance characteristics that lead to the ability to measure product and process quality levels desired by the cleanroom owner.
Of the 14 recommended cleanroom qualification tests, choice of which tests will apply to a particular cleanroom is per agreement between buyer and seller, that is, customer and supplier.
There are three major annexes in ISO 14644-3. Annex A lists all the recommended tests and provides a means of defining the sequence in which these tests are to be utilized in classifying and qualifying a cleanroom or clean zone.
Annex B details the individual test methods so there can be no misunderstanding between customer and supplier. How the test is conducted, any test limitations, and how the test data is reported are given here.
Annex C of ISO 14644-3 lists all the test instrumentation used by the 14 recommended tests. The performance parameters for each instrument are given. What are the sensitivity limits, measuring range, acceptable error, response time, calibration interval, counting efficiency, data display, etc.
TITLE: Cleanrooms and associated controlled environmentsPart 4: Design and Construction
SCOPE: Specifies the requirements for the design and construction of cleanroom facilities
STATUS: Currently out for FDIS vote by all the nations of the ISO. The voting deadline is February 2001.
ISO 14644-4 covers all aspects of the design and construction of cleanrooms.
ISO 14644-4 is a primer to intelligent cleanroom design and construction. It starts with requiring a clear definition of the roles of the primary parties involved in a cleanroom project, i.e. the customer and the supplier as well as ancillary parties such as consultants, regulatory authorities and service organizations.
The Scope of Requirements section necessitates that the purpose of the cleanroom and the operations to be carried out within it are clearly defined. Parameters such as utility needs, process support, dimensions, overall layout, entry and exit of materials and personnel must be defined. Measurement control and monitoring parameters and the influence of external environmental factors are all part of this specification process.
The Scope of Requirements section details the assignment of tasks for the preparation, approval, execution, supervision, documentation, statement of criteria, basis of design, detailed design, construction, testing, commissioning, qualification and the performance and witnessing of tests. More succinctly, it states who is responsible for what.
Second is the Planning and Design section, which provides an overview of the details necessary for proper cleanroom design. How does the design address the specification of requirements described above? For example, a contamination control concept should be developed for each zone of a cleanroom installation. Cost factors, timescale factors, design options, constructability of design and project flexibility are all covered in this section.
Third is the section on Construction and Start-up. Specific contamination control requirements apply to construction activities whether performed on the job site or in a remote location. A cleanroom construction protocol and clean-up procedure should be established for all locations as part of an overall quality program. Security and access control should be part of a continuous clean-up plan. Thorough cleaning is required before start-up.
After completion of construction comes the critical phase of Testing and Approval of the cleanroom. This section requires that all personnel in charge of the new cleanroom be properly trained in its operation. Such training is to include cleanroom operations, maintenance and in-process control.
Testing and Approval comes in three distinct stagesconstruction approval (does the cleanroom comply with the design requirements?), functional approval (do all parts of the cleanroom operate together to achieve the required "as-built" or "at rest" state?) and operational approval (does the cleanroom operate properly under the "operational" state?).
It is important that proper documentation be created and maintained. There is an entire section of ISO 14644-4 devoted to suggestions for appropriate documentation. Included are "as built" drawings, test and certification data, operational and maintenance manuals, spare parts lists and training records.
There are eight comprehensive Annex sections to ISO 14644-4, which are helpful in detailing suggested design criteria, materials of construction, approval stages, installation layout, construction procedures, environmental control requirements and air cleanliness control.
TITLE: Cleanrooms and associated controlled environmentsPart 5: Cleanroom Operations
SCOPE: Specifies the basic requirements for operating a cleanroom.
STATUS: Currently awaiting ISO issuance of a 5-month ISO DIS vote by all the nations of ISO.
This document covers all aspects of operating a cleanroom no matter what class of cleanliness or type of product produced therein. It is a referee document for smart cleanroom operation.
There are six major areas of concern. This first is "Operational Systems" where attention is focused on establishing a framework for providing quality products and processes in a cleanroom environment. Covered are such factors as contamination risk assessment, training procedures, mechanical equipment operation and maintenance, safety, and proper documentation to prove that appropriate procedures are in place and being followed.
The second major area is "Cleanroom Clothing." Who wears what? How is it put on? When should it be replaced or laundered? What type of fabric is appropriate to your situation? We all recognize that the primary function of cleanroom clothing is to act as a barrier that protects products and processes from human contamination. The degree of enclosing an individual is process and product dependent. It could be done by a simple lab coat or a totally enclosed body suit with self-supporting breathing device.
The third major area is "Personnel." Only properly trained personnel should be allowed to enter a cleanroom. To do otherwise is to create additional risk. Personal hygiene, cosmetics and jewelry can cause contamination problems. What is your policy in these areas? How should people enter and leave clean space? What is your personnel emergency response procedure?
Fourth is the concern for the impact of "Stationary Equipment." How clean should this equipment be before it is placed in a cleanroom? How should it be moved into this space and set in place? What kind of maintenance will be required? What types of ongoing support services will be needed? What will be the impact of these factors on control of contamination?
The fifth major area of concern covers "Portable Equipment and Materials" that is, items easily transported in and out of the cleanroom. What procedures are needed for control of these items in a cleanroom? Do some materials require protective storage and isolation? How is this done? How are waste materials collected, identified and removed from a cleanroom? Should there be a separate set of tools kept in the cleanroom? What items require sterilization? What items in the cleanroom have out-gassing properties? What items cause static? Because all consumable items in a cleanroom are potential contamination sources, what do you do to control them from entry through use to disposal?
The last area of concern is "Cleanroom Cleaning," otherwise known as "Housekeeping." Outlined are detailed cleaning methods and procedures along with personnel responsibilities. Here again, personnel training is important. How do you clean properly, how frequently and what contamination checks are required? Do you have an assessment system in place for evaluating your housekeeping? What special requirements are required, particularly in areas of risk due to hazardous material, hazardous equipment, equipment location, etc.? How aggressive are your cleaning compounds? How do you avoid adding contamination by your own cleaning procedures?
TITLE: Cleanrooms and associated controlled environmentsPart 6: Terms, definitions, & units.
SCOPE: Defines those terms that require more specific description than is found in normal dictionary sources.
STATUS: Will be sent out for DIS vote by all the nations of ISO in early 2001.
ISO 14644-6 is the repository of all the common terms, definitions and units used in all the other ISO 14644 and ISO 14698 documents pertaining to cleanrooms and associated controlled environments.
It is a database of terms that is applicable to the new family of ISO cleanroom standards. Currently there are 162 entries in this database with more to be added before its publication. It has been important to harmonize these definitions so they have uniformity of meaning across these new cleanroom standards.
This 26-page standard is divided into two main sections. Annex A alphabetically lists all terms and definitions for ease of reference. Annex B lists these same terms and definitions by major category affinity group. For example, there are 23 specific terms listed under Biological Measurement. There are another 29 terms listed under Particle Measurement.
TITLE: Cleanrooms and associated controlled environmentsPart 7: Separative enclosures (clean air hoods, glove boxes, isolators and minienvironments).
SCOPE: Specifies the minimum requirements for the design, construction, installation, testing and approval of separative enclosures in those respects where they differ from cleanrooms.
STATUS: Currently awaiting ISO issuance of a 5-month ISO DIS vote by all the nations of ISO.
A "separative enclosure" is a cleanroom without any people inside. It is usually relatively small in size, but not necessarily so. Examples are clean air hoods, glove boxes, isolators and minienvironmentsterms that, in many cases, are industry specific. For example, what the healthcare industry refers to as an isolator, the microelectronics industry refers to as a minienvironment. However, the healthcare user quite often has to sterilize his enclosure, whereas the microelectronic user does not. This leads to significant design and construction differences.
By way of clarification, prior to May 2000, ISO 14644-7 was referred to as "Enhanced clean devices." The writers of this ISO document were not satisfied with its title, and it was changed to the current term "Separative enclosures" because this term is more descriptive and definitive of these types of clean environments.
The term "Separative enclosures" is generic as is the subject matter covered in ISO 14644-7. Separative enclosures encompass a wide range of configurations from open unrestricted air over-spill to totally contained hard wall containers. They provide the appropriate level of protection from unwanted particle, microbiological, gaseous and liquid contamination, as well as worker safety and comfort.
They provide for special atmospheres and bio-decontamination, as well as remote manipulation of enclosed manufacturing processes.
In writing this ISO-14644-7 standard, all factors of a clean environment had to be considered in miniature. Such issues of material ingress and egress, personnel interface, installation and maintenance, support services, testing and certification had to be considered for a very different style of clean enclosure than what is required for a typical cleanroom.
ISO 14644-7 is recommended for those who manufacture or use clean-air hoods, glove boxes, isolators, minienvironments or like-minded enclosures. Such enclosures may be no-wall, soft-wall or hard-wall, but they share a unifying conceptthat a continuum of separation exists between the operator and the operation.
The standard covers such issues as design and construction, risk analysis, contamination control concept, assessment of external influences, access devices, transfer devices, installation, and testing and approval procedures, including glove breech test, leak test, pressure differential test and routine alarm requirements.
There are many other aspects of these separative enclosures for which guidance is provided in the detailed annexes.
Probably the most valuable is Annex A, which spells out the newly created "Separation continuum concept." This is the key basis for defining a particular separative enclosure. It weighs the separation means (from aerodynamic to physical) against the assurance of maintaining separation (from low to high). In simple terms, anything from an airflow curtain to a stainless steel wall can be used, recognizing that the more physical the barrier, the higher the assurance of separation.
Additional annexes address such issues as air handling and gas systems, access device options in detail, transfer device options in detail, leak detection and testing methods, pressure integrity of enclosures and support devices, as well as design and construction parameters.
TITLE: Cleanrooms and associated controlled environmentsPart 8: Classification of airborne molecular contamination.
SCOPE: Covers the classification of molecular contamination in terms of airborne concentrations of specific compounds or chemicals and provides a protocol that includes test methods and analysis for concentrations between 10 and 10-12 grams/cubic meter.
STATUS: Currently being developed by ISO/TC209 Working Group 8. It is expected to be published as a DIS by December 2001.
ISO-14644-8 is the base document for controlling molecular contamination in cleanrooms and associated controlled environments. It includes the special requirements of Separative Enclosures (see ISO 14644-7) such as minienvironments, isolators, glove boxes and clean hoods.
Airborne molecular contamination (AMC) is the presence in a cleanroom atmosphere of chemicals (non-particle) in the gaseous, vapor or liquid state which may have a deleterious effect on a product, process or analytical instrument.
Surface molecular contamination (SMC) in a cleanroom is the presence on the surface of a product or analytical instrument of chemicals (non-particle) in the gaseous, vapor or liquid state which may have a deleterious effect.
Outgassing is gaseous products released from a material under specified conditions of temperature and pressure.
ISO 14644-8 provides a formal classification system of AMC. This system has an ISO descriptor which is as follows:
AMC.ISO Class N:a:b; (c); (d)
N = the logarithmic index of concentration expressed in grams/cubic meter
a = the type of compound (acid, base, organic, inorganic)
b = the specified measuring method (sampling and analytical)
c = the optical extension for a particular species
d = the optional extension to include elapsed time
Let's review a few examples:
1) "AMC: ISO Class -6:A:IMP-IC; (HCI); (-)"
Translated this is an airborne concentration of HCl (hydrogen chloride) acid of 10-6 grams/cubic meter, sampled with an impinger (IMP) and analyzed with ion chromatography (IC) and no elapsed time period (-).
2) AMC, ISO Class -5:0:SOR-GC-MS; (DOP); (2016 post operational)
Again translated this expresses an airborne concentration of DOP which is a species of organic (o) at 10-5 grams/cubic meter sampled with a sorbent tube (SOR), analyzed by gas chromatography mass spectroscopy (GC-MS) at an elapsed time of 12 weeks expressed as 2016 hours post operational, i.e., after 12 weeks of cleanroom operation.
There is also a provision for measuring surface molecular contamination and this is expressed in a similar fashion in the next example.
3) SMC: ISO Class -8:0: DIFF-GC-MS; (DOP); (24)
The translation here is surface concentration of DOP (an organic) 10-8 grams/cubic meter after 24 hours exposure as sampled with passive diffusive sampling (DIFF) analyzed using gas chromatography mass spectroscopy (GC-MS).
ISO 14644-8 as currently under development has been well organized to give guidance for developing a sound procedure assessing the parameters affecting airborne and surface molecular contamination in a cleanroom or other controlled environment.
The AMC and SMC classifications for molecular contamination are entirely separate from the classification of air cleanliness found in ISO 14644-1 for particulate air cleanliness.
Sources of molecular contamination can be from outdoor air, construction materials cross-contamination within a facility, and from daily cleanroom operation and maintenance, including garments, cleaning fluids, packaging materials and portable equipment.
ISO 14644-8 provides a detailed checklist of potential cleanroom-related molecular contamination sources. In addition, it lists typical contaminating chemicals and substances. There is also a listing of typical methods for the measurement and analysis of molecular contamination both passive and dynamic. Five different sampling instruments and 16 different analysis methods are shown, and these are by no means all the options available. However, the instruments and methods must be measurable, verifiable and repeatable.
The idiosyncrasies of barrier technology, as found in isolators, minienvironments, glove boxes, clean hoods and the impact of molecular contamination therein, is addressed in ISO 14644-8.
The last 18 pages of this document clearly spell out standard evaluation methods for acids, bases, organics (condensables) and inorganics (dopants). This section provides a valuable guide for measuring the concentration of molecular contamination.
The control of molecular contamination is a field still in its infancy but growing and changing rapidly. It is important to our future. ISO 14644-8 does not recommend any specific control program or device. Rather it provides the means for identifying and assessing the amount of molecular contamination present. How it is best controlled must be determined by the facility involved through determining the source, the carrier, and the resultant interactions on product, process and yield, etc. Elimination at the source is the best place to start. Establishing levels of acceptance is another key parameter.
Molecular contamination can also be controlled by chemical filtration systems, dilute chemistry, alternate chemistries, event control, that is, spills or product handling and common sense when sources are identified and quantified.
TITLE: Cleanrooms and associated controlled environmentsBiocontamination control Part 1: General principles and methods.
SCOPE: Describes the principles and basic methodology for a formal system to assess and control biocontamination in cleanrooms.
STATUS: FDIS document is awaiting issue by ISO Geneva for an FDIS vote by all the member ISO nations in early 2001.
Good hygiene practices have become increasingly important in modern society. As we increase international trade in hygiene-sensitive products, there is a strong requirement for stable and safe products, particularly in the healthcare field.
To achieve this stability and safety requires good control of biocontamination in the design, specification, operation and control of cleanrooms and associated controlled environments.
ISO 14698-1 provides guideline principles for establishing and maintaining a formal system to assess and control biocontamination in these special environments. It is not a general standard covering all aspects of biocontamination control. It is specific to cleanrooms and associated controlled environments.
A formal system of biocontamination control will assess and control factors that can affect the microbiological quality of a process or product. There are a number of formalized systems to achieve this, such as Hazardous Analysis Critical Control Point (HACCP), Fault Tree Analysis (FTA), Failure Mode and Effect Analysis (FMEA) and others.
ISO 14698-1 is concerned only with a formal system to address microbiological hazards in cleanrooms. Such a system must have the means to identify potential hazards, determine the resultant likelihood of occurrence, designate risk zones, establish measures of prevention or control, establish control limits, establish monitoring and observation schedules, establish corrective actions, establish training procedures, and provide proper documentation.
A formal system requires a sampling procedure for the detection and monitoring of biocontamination in risk zones. Biocontamination can be airborne, on surfaces, on clothing, in liquids, even in the laundering of cleanroom textiles such as garments and wipers.
Target, alert and action levels must be determined for a given risk zone. Such levels will determine the required remediation effort. All of these impact product quality.
A biocontamination sampling program must be established for cleanroom air, walls, floors, ceilings, process equipment, raw materials, process liquids and gases, furniture, storage containers, personal attire and protective clothing. Sampling frequency, site location, sample identification, culturing methods and evaluation criteria must be part of this formal system for biocontamination control.
ISO-14698-1 provides a foundation for developing a formal system for biocontamination control in cleanrooms. It provides detailed guidance on how to measure airborne biocontamination, how to validate air samples and how to measure biocontamination of surfaces, liquids and textiles used in cleanrooms; it also provides guidance for validating laundering processes and how to provide proper personnel training.
TITLE: Cleanrooms and associated controlled environmentsBiocontamination control Part 2: Evaluation and interpretation of biocontamination data.
SCOPE: Gives guidance on basic principles and methodology requirements for all microbiological data evaluation obtained from sampling for viable particles in specified risk zones in cleanrooms.
STATUS: FDIS document is awaiting issue by ISO Geneva for an FDIS vote by all the member ISO nations in early 2001.
ISO 14698-2 is designed to be used in conjunction with ISO-14698-1. It provides guidelines for how to estimate and evaluate biocontamination data from microbial monitoring of risk zones. To determine the presence and significance of biocontamination is a multi-step task. Sampling techniques, time factors, culturing techniques, analysis method (qualitative or quantitative estimates) all have to be carefully planned. Target, alert and action levels have to be determined for each risk zone based upon an initial biocontamination data collection and evaluation plan.
Each enumeration technique must be validated considering the viable particles involved.
Good data collection and evaluation documentation is necessary to determine trend analysis and the quality of risk zones. Out-of-specification results require verification. "Did we have a true result or is it a laboratory error?" ISO 14698-2 provides the guidance for answering this question accurately.
TITLE: Cleanrooms and associated controlled environmentsBiocontamination control Part 3: Measurement of the efficiency of processes of cleaning and/or disinfection of inert surfaces bearing biocontamination wet soiling or biofilms.
SCOPE: Describes guidance for a laboratory method for measuring the efficiency of cleaning an inert surface.
STATUS: Passed an ISO DIS vote in July 1999. Has been subsequently determined to be too limiting to be issued as an ISO Standard.
The ISO Technical Committee ISO/TC209 determined at its May 2000 meeting to issue ISO 14698-3 as an ISO Technical Report. It will be available for informational purposes only. It will not become an ISO Standard.
Editor's Note: These documents may be purchased for a nominal fee from the Institute of Environmental Sciences and Technology (IEST), 940 East Northwest Highway, Mt. Prospect, IL 60059. Phone: (847) 255-1561; Fax: (847) 255-1699 or www.iest.org.
Richard A. Matthews is founder of Filtration Technology Inc. (Greensboro, NC) and president of Micron Video International. He is chairman of the International Organization for Standardization Technical Committee ISO/TC209 "Cleanrooms and associated clean environments," and past president of the IEST. He is on the CleanRooms Editorial Advisory Board.
Where it all began
The new family of ISO Global Cleanroom Standards was written by experienced operations personnel whose practical experience had great influence in the development of these new standards.
ISO/TC209, the ISO Technical Committee on "Cleanrooms and associated controlled environments," draws from over 1,000 volunteers from 37 countries to create realistic standards for practical use in the global cleanroom community.
ISO14644-1 is the keystone for the full series of ISO global cleanroom standards. The use of this document became mandatory in the European Union on November 1, 1999. Other parts of the world have also adopted 14644-1 as their baseline cleanroom (clean space) classification document. ISO 9000-certified organizations are required to utilize ISO 14644-1 in defining their clean space.RAM
DIS: Draft International Standard
FDIS: Final Draft International Standard
ISO: International Organization of Standardization
TC: Technical Committee