ISO 14644-12:2018

INTERNATIONAL ISO
STANDARD 14644-12
First edition
2018-08
Cleanrooms and associated controlled
environments —
Part 12:
Specifications for monitoring air
cleanliness by nanoscale particle
concentration
Salles propres et environnements maîtrisés apparentés —
Partie 12: Spécification de la propreté de l'air en fonction de la
concentration des nanoparticules
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General . 1
3.2 Size . 2
3.3 Airborne particles . 2
3.4 Occupancy states . 3
3.5 Measuring apparatus . 3
4 Monitoring . 3
4.1 General . 3
4.2 Principle . 3
4.3 Methods . 3
5 Test report . 4
Annex A (informative) Reference method for monitoring by condensation particle counting.5
Annex B (informative) Particle counting efficiency and particle size cutoff .8
Bibliography .11
Foreword
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This document was prepared by Technical Committee ISO/TC 209, Cleanrooms and associated controlled
environments.
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A list of all parts in the ISO 14644 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

Introduction
Cleanrooms and associated controlled environments provide the control of contamination to levels
appropriate for accomplishing contamination-sensitive activities. Products and processes that benefit
from the control of contamination include those in such industries as aerospace, microelectronics,
pharmaceuticals, medical devices, healthcare and food.
The normative requirements in the first editions of ISO 14644-1 and ISO 14644-3 were limited to
classification of particles greater than 100 nm. However, informative material was included in both
documents for airborne particles smaller than 100 nm. At the time these documents were written;
particles smaller than 100 nm were called ultrafine particles rather than the more recent term,
nanoparticles.
1)
In the second editions of ISO 14644-1 and ISO 14644-3 , sections on ultrafine particles have been
removed and these are incorporated, in modified form, in this document. Supporting information has
also been drawn from documents developed elsewhere, for example by ISO/TC 229, Nanotechnologies.
Nanotechnology typically deals with material in the size range of approximately 1 nm to 100 nm.
As part of the long-term trend of manufacturing products with ever smaller feature size to improve
performance, many industries utilizing cleanrooms (such as microelectronics and those related to
health) now have products in the nanoscale.
Nanoparticles are man-made. Other particles in the nanoscale size range can originate as incidental by-
product emissions from industrial process or additionally as naturally occurring particles. A cleanroom
with a nanotechnology-based process can contain nanoscale particles from all three sources.
Nanoparticles or ultrafine particles differ from sub-micron and macro-particles in origin, chemical
properties and transport behaviour. Most sub-micron and macro particles in cleanrooms can be related
to human activity. Nanoparticles are generated by electrostatic discharge, chemical reactions, such
as oxidation, and gas phase nucleation. Material properties of nanoparticles are expected to differ
from bulk properties with potentially greater reactivity and sometimes enhanced toxicity. Transport
of nanoparticles is dominated by air flow, just like sub-micron particles. However, diffusion of
nanoparticles and mobility in electrical fields increases rapidly with decreasing size. As a consequence,
nanoparticles have higher coagulation rates in the air and deposition rates on surfaces are higher
than larger sized particles. Therefore, it is not expected that the classification curves as described in
ISO 14644-1 can be simply extrapolated to smaller particles than the stated lower limit.
Ultra Low Particulate Air (ULPA) filters remove nanoparticles with high efficiency, preventing
penetration from the atmosphere and recirculated air. Therefore, the majority of the nanoparticles
in cleanrooms are process related. For many cleanrooms, the composition of sub-micron and macro
particles is comparable. For nanoparticles, each cleanroom has nanoparticles corresponding to the
specific process. Therefore, measurement of the nanoparticle concentration is only suitable when the
cleanroom is in an “operational” state. In the “as-built” or “at-rest” state, the lack of process related
particles leads to data that do not correlate to the realistic conditions.
See Bibliography references [1] to [18] for background information on particle size characteristics/
properties.
1) Under preparation. (Stage at the time of publication: ISO/DIS 14644-3.)
INTERNATIONAL STANDARD ISO 14644-12:2018(E)
Cleanrooms and associated controlled environments —
Part 12:
Specifications for monitoring air cleanliness by nanoscale
particle concentration
1 Scope
This document covers the monitoring of air cleanliness by particles in terms of concentration of
airborne nanoscale particles.
For monitoring purposes, only populations of particles with a lower size limit of 0.1 microns (100 nm)
or less – “nanoscale” – are considered.
The monitoring given in this document is for use mainly in “operational” states.
NOTE 1 For the purposes of this document, reference is made to “nanoscale particles”, which means all nano-
objects having one (nanoplate), two (nanofibre) or three (nanoparticle) dimensions in the nanoscale.
NOTE 2 As a consequence, the specifications for monitoring air cleanliness by nanoscale particle
concentration of the cleanroom in operational state also considers process specifics, e.g., used equipment,
personnel behaviour, etc.
NOTE 3 Health and safety considerations are excluded from this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at https: //www .electropedia .org/
3.1 General
3.1.1
cleanroom
room within which the number concentration of airborne particles is controlled and classified, and
which is designed, constructed and operated in a manner to control the introduction, generation and
retention of particles inside the room
Note 1 to entry: The class of airborne particle concentration is specified.
Note 2 to entry: Levels of other cleanliness attributes such as chemical, viable or nanoscale (3.2.1) concentrations
in the air, and also surface cleanliness in terms of particle, nanoscale, chemical and viable concentrations might
also be specified and controlled.
Note 3 to entry: Other relevant physical parameters might also be controlled as required, e.g. temperature,
humidity, pressure, vibration and electrostatic.
[SOURCE: ISO 14644-1:2015, 3.1.1]
3.1.2
clean zone
defined space within which the number concentration of airborne particles is controlled and classified,
and which is constructed and operated in a manner to control the introduction, generation and retention
of contaminants inside the space
Note 1 to entry: The class of airborne particle concentration is specified.
Note 2 to entry: Levels of other cleanliness attributes such as chemical, viable or nanoscale (3.2.1) concentrations
in the air, and also surface cleanliness in terms of particle, nanoscale, chemical and viable concentrations might
also be specified and controlled.
Note 3 to entry: A clean zone(s) can be a defined space within a cleanroom (3.1.1) or might be achieved by a
separative device. Such a device can be located inside or outside a cleanroom.
Note 4 to entry: Other relevant physical parameters might also be controlled as required, e.g. temperature,
humidity, pressure, vibration and electrostatic.
[SOURCE: ISO 14644-1:2015, 3.1.2]
3.2 Size
3.2.1
nanoscale
length range approximately from 1 nm to 100 nm
Note 1 to entry: Properties that are not extrapolations from a larger size are predominantly exhibited in this
length range.
[SOURCE: ISO/TS 80004-2:2015, 2.1]
3.2.2
particle size cutoff
D
particle size at which the counting efficiency is 50 %
Note 1 to entry: See Annex B for an explanation of counting e
...