ISO 14644-8:2022(en)

Foreword

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

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This document was prepared by Technical Committee ISO/TC 209, Cleanrooms and associated controlled environments, in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 243, Cleanroom technology, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This third edition cancels and replaces the second edition (ISO 14644-8:2013), of which it constitutes a minor revision. The changes are as follows:

•  the term class (classification, classified) changed to grade or assessment where appropriate;

•  3.1.2, definition revised;

•  Bibliography updated;

•  minor editorial changes.

A list of all parts in the ISO 14644 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Cleanrooms and associated controlled environments provide for the control of airborne particulate contamination to levels of cleanliness appropriate for accomplishing process activities sensitive to a range of contaminants. Products and processes that benefit from the control of airborne contamination include those in such industries as aerospace, microelectronics, pharmaceuticals, medical devices, food, healthcare, optics, instrumentation, vacuum technology, coatings, photovoltaics, displays, LEDs, coatings, automotive and surface analysis.

In some of these industries, the product or process can be sensitive to, or can be destroyed by, chemical contamination resulting from chemicals that are present due to external, process or other generated sources.

Within this document, the presence of chemicals is expressed as air chemical contamination. Chemical contamination is a three-step event. The first step is generation due to external sources such as process leakage, construction material, personnel or material outgassing. The second step is transport as airborne chemical contamination. The third step is sorption on the sensitive surface, which can be quantified as a surface chemical contamination.

The generating materials and the surfaces where sorption takes place will have a large influence on the steps of generation and sorption in addition to the actual air contamination. Thus, for these two steps, not only the contaminants but also the involved bulk and surfaces need to be defined. In order to make a standard generally applicable to any type of cleanroom or associated controlled environment, air chemical cleanliness (ACC) has been chosen for the level assessment.

This document assigns ISO grading levels to be used to specify the level of ACC within a cleanroom and associated controlled environment, where the product or process is deemed to be at risk from air chemical contamination.

For level assessment purposes, this document provides guidance for a range of ACC levels and provides standard protocols for specifying such levels with regard to chemical compounds, methods of test and analysis, and time weighted factors.

Annexes A to D contain the following information:

•  parameters for consideration: Annex A;

•  typical contaminating chemicals and substances: Annex B;

•  typical methods of measurement and analysis: Annex C;

•  considerations of specific requirements for separative devices: Annex D.

This document is one of a series of standards concerned with cleanrooms and contamination control. Many factors besides ACC need to be considered in the design, specification, operation and control of cleanrooms and other controlled environments. These features are recognized in this document and covered in some detail in other parts of the International Standards prepared by ISO/TC 209, including the ISO 14698 series. In some circumstances, relevant regulatory agencies can impose supplementary policies or restrictions. In such situations, appropriate adaptations of this document can be required.

NOTE When assessment of ACC at critical control point(s) is used as an additional cleanliness attribute to classification of air cleanliness by airborne particle concentration in accordance with ISO 14644-1, then the space can be described as a cleanroom or clean-zone. If ACC is used alone, then the space must be described as a controlled zone.