SIST EN ISO 14644-17:2021
(Main)Cleanrooms and associated controlled environments - Part 17: Particle deposition rate applications (ISO 14644-17:2021)
Cleanrooms and associated controlled environments - Part 17: Particle deposition rate applications (ISO 14644-17:2021)
This document gives direction on the interpretation and application of the results of the measurement
of particle deposition rate on one or more vulnerable surfaces in a cleanroom as part of a contamination
control programme. It provides some instructions on how to influence the particle deposition rate and
reduce the risk of particle contamination on vulnerable surfaces.
This document gives information on how a cleanroom user can use the particle deposition rate
measurements to determine limits that can be set for macroparticles on vulnerable surfaces. It also
gives a risk assessment method by which an acceptable risk of deposition of particles onto vulnerable
surfaces in a cleanroom can be established and, when this is not achieved, methods that can be used to
reduce the particle deposition rate.
An alternative to the particle deposition rate is the particle obscuration rate which determines the rate
of increase of coverage of particles onto an area of surface over time. The particle obscuration rate can
be used in an analogous way to the particle deposition rate and the required particle obscuration rate
for a specified surface can be calculated and the risk from deposited particles reduced.
This document does not:
— provide a method to classify a cleanroom with respect to particle deposition rate or particle
obscuration rate;
— directly consider the deposition of microbe-carrying particles, although they can be treated as
particles;
— give any consideration to surface deposition by contact as, for example, when personnel touch a
product and contamination is transferred.
Reinräume und zugehörige Reinraumbereiche - Teil 17: Anwendungen zur Partikelabscheidungsrate (ISO 14644-17:2021)
Dieses Dokument enthält Anweisungen für die Auswertung und Anwendung der Messergebnisse der Partikelablagerungsrate auf einer oder mehreren empfindlichen Oberflächen in einem Reinraum im Rahmen eines Programms zur Kontaminationskontrolle. Es umfasst ferner Anleitungen, wie die Partikelablagerungs-rate beeinflusst und die Gefahr einer partikulären Kontamination auf empfindlichen Oberflächen verringert werden kann.
Dieses Dokument beschreibt, wie Nutzer eines Reinraums mit Hilfe der Messungen der Partikelablagerungs-rate Grenzwerte festlegen können, die für Makropartikel auf empfindlichen Oberflächen gelten. Es umfasst ferner ein Verfahren zur Risikobewertung, mit dem ein annehmbares Risiko der Partikelablagerung auf empfindlichen Oberflächen in einem Reinraum ermittelt werden kann und, wenn dieses nicht erreicht wird, Verfahren, mit denen die Partikelablagerungsrate reduziert werden kann.
Eine Alternative zur Partikelablagerungsrate ist die partikuläre Trübungsrate, mit der die Anstiegsrate der Partikelansammlung auf einer bestimmten Fläche während einer bestimmten Zeit ermittelt werden kann. Die partikuläre Trübungsrate kann analog zur Partikelablagerungsrate angewandt werden, die erforderliche partikuläre Trübungsrate für eine bestimmte Oberfläche kann berechnet und das Risiko durch abgelagerte Partikel verringert werden.
Folgendes leistet dieses Dokument nicht:
- Bestimmung eines Verfahrens zur Klassifizierung eines Reinraums in Bezug auf die Partikelablagerungs-rate oder partikuläre Trübungsrate;
- direkte Betrachtung der Ablagerung mikrobentragender Partikel (MCP, en: microbe-carrying particles), wenngleich diese als Partikel behandelt werden können;
- Betrachtung der Ablagerung auf Oberflächen durch Kontakt, zum Beispiel wenn Mitarbeiter ein Produkt berühren und eine Kontamination auf diese Weise übertragen wird.
Salles propres et environnements maîtrisés apparentés - Partie 17: Applications de taux de dépôt de particules (ISO 14644-17:2021)
1 Domaine d'application Le présent document donne des indications concernant l'interprétation et l'application des résultats du mesurage du taux de dépôt de particules sur une ou plusieurs surfaces sensibles dans une salle propre dans le cadre d'un programme de maîtrise de la contamination. Il fournit des instructions relatives à la manière d'influer sur le taux de dépôt de particules et de réduire le risque de contamination des surfaces sensibles par des particules.
Le présent document explique comment l'utilisateur d'une salle propre peut se servir des mesurages du taux de dépôt de particules pour déterminer les limites qui peuvent être définies pour les macroparticules sur les surfaces sensibles. Il propose également une méthode d'évaluation permettant d'établir un risque acceptable de dépôt de particules sur des surfaces sensibles dans une salle propre et, lorsque cela n'est pas réalisé, des méthodes pouvant être utilisées pour réduire le taux de dépôt de particules.
Le taux d'occultation par les particules constitue une alternative au taux de dépôt de particules; il permet de déterminer le taux d'augmentation de la zone de couverture des particules sur une surface dans le temps. Le taux d'occultation par les particules peut être utilisé de la même manière que le taux de dépôt de particules; il est possible de calculer le taux d'occultation par les particules requis pour une surface donnée et de réduire le risque de dépôt de particules.
Le présent document:
— ne fournit pas de méthode permettant de classer une salle propre en fonction du taux de dépôt de particules ou du taux d'occultation par les particules;
— ne traite pas directement du dépôt de particules porteuses de micro-organismes, bien que ces dernières puissent être considérées comme des particules;
— ne s'applique pas aux dépôts en surface par contact, comme par exemple lorsque le personnel touche un produit et que la contamination est ainsi transférée.
Čiste sobe in podobna nadzorovana okolja - 17. del: Aplikacije glede hitrosti usedanja delcev (ISO 14644-17:2021)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 14644-17:2021
01-april-2021
Čiste sobe in podobna nadzorovana okolja - 17. del: Aplikacije glede hitrosti
usedanja delcev (ISO 14644-17:2021)
Cleanrooms and associated controlled environments - Part 17: Particle deposition rate
applications (ISO 14644-17:2021)
Reinräume und zugehörige Reinraumbereiche - Teil 17: Anwendungen zur
Partikelabscheidungsrate (ISO 14644-17:2021)
Salles propres et environnements maîtrisés apparentés - Partie 17: Applications de taux
de dépôt de particules (ISO 14644-17:2021)
Ta slovenski standard je istoveten z: EN ISO 14644-17:2021
ICS:
13.040.35 Brezprašni prostori in Cleanrooms and associated
povezana nadzorovana controlled environments
okolja
SIST EN ISO 14644-17:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 14644-17:2021
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SIST EN ISO 14644-17:2021
EN ISO 14644-17
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2021
EUROPÄISCHE NORM
ICS 13.040.35
English Version
Cleanrooms and associated controlled environments - Part
17: Particle deposition rate applications (ISO 14644-
17:2021)
Salles propres et environnements maîtrisés apparentés Reinräume und zugehörige Reinraumbereiche - Teil
- Partie 17: Applications de taux de dépôt de particules 17: Anwendungen zur Partikelabscheidungsrate (ISO
(ISO 14644-17:2021) 14644-17:2021)
This European Standard was approved by CEN on 6 January 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14644-17:2021 E
worldwide for CEN national Members.
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SIST EN ISO 14644-17:2021
EN ISO 14644-17:2021 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 14644-17:2021
EN ISO 14644-17:2021 (E)
European foreword
This document (EN ISO 14644-17:2021) has been prepared by Technical Committee ISO/TC 209
"Cleanrooms and associated controlled environments" in collaboration with Technical Committee
CEN/TC 243 “Cleanroom technology” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2021, and conflicting national standards shall
be withdrawn at the latest by August 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 14644-17:2021 has been approved by CEN as EN ISO 14644-17:2021 without any
modification.
3
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SIST EN ISO 14644-17:2021
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SIST EN ISO 14644-17:2021
INTERNATIONAL ISO
STANDARD 14644-17
First edition
2021-02
Cleanrooms and associated controlled
environments —
Part 17:
Particle deposition rate applications
Salles propres et environnements maîtrisés apparentés —
Partie 17: Applications de taux de dépôt de particules
Reference number
ISO 14644-17:2021(E)
©
ISO 2021
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 3
5 Particle deposition rate methodology . 4
5.1 General . 4
5.2 Establishing the particle deposition rate required for control of particle deposition
on vulnerable surfaces . 4
5.3 Particle deposition rate for demonstrating control of particle contamination . 5
6 Measurement of particle deposition rate . 5
7 Particle deposition rate level . 6
8 Documentation . 7
Annex A (informative) Measurement of particle deposition rate . 8
Annex B (informative) Examples of particle deposition rate measurements .12
Annex C (informative) Measurement of the particle obscuration .16
Annex D (informative) Relationship between particle deposition rate and airborne
concentration of particles .19
Annex E (informative) Assessment and control of particle deposition .20
Bibliography .25
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
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).
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.
A list of all parts in the ISO 14644 series can be found on the ISO website.
iv © ISO 2021 – All rights reserved
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
Introduction
Cleanrooms and associated controlled environments are used to control contamination to levels
appropriate for accomplishing contamination-sensitive activities. Products and processes that benefit
from the control of contamination include those in industries such as aerospace, microelectronics,
optics, nuclear, food, healthcare, pharmaceuticals, and medical devices.
ISO 14644-1:2015 considers airborne particles in cleanrooms and classifies cleanroom cleanliness
by maximum permitted concentrations, and both ISO 14644-9:2012 and IEST -STD -CC1246E: 2013
consider the concentration of surface particles. This document considers the rate of particle deposition
[5]
onto cleanroom surfaces and is based on VCCN Guideline 9 . The particle deposition rate is important,
as the probability of contamination by airborne particles onto contamination sensitive, vulnerable
surfaces, such as manufactured products, is directly related to the particle deposition rate.
ISO 14644-3:2019 gives an overview of methods for the determination of deposition of particles, larger
or equal to 0,1 µm. In this document, the focus is on the rate that macroparticles larger than 5 µm
deposit on surfaces, and the application of this information to controlling contamination in cleanrooms.
Various sizes of particles are generated in cleanrooms by personnel, machinery, tools, and processes,
and distributed by air moving about the cleanroom. According to ISO 14644-1, cleanrooms and
controlled environments with a particle class of the ISO 5 series, or cleaner, contain zero or very low
concentrations of airborne particles larger than 5 µm. However, in operating cleanrooms, many more
particles in the size range of 5 µm to 500 µm, and greater, are found on surfaces than suggested by the
classification limits of the size of particles given in ISO 14644-1. The main reason for this is that the
largest particles in the range of sizes of macroparticles are not counted by particle counters because
of deposition losses in sampling tubes, and at the entry to and within particle counters. Also, for the
same reason, only a proportion of the smaller particles in the range of sizes is measured. In many cases,
large particles cause contamination problems and their presence and potential for deposition onto
contamination sensitive, vulnerable surfaces is best determined by measuring the particle deposition
rate onto surfaces.
Particles smaller than 5 µm are most likely to be removed from the cleanroom air by the ventilation
system but, for particles above 10 µm, more than 50 % is removed from the air by surface deposition.
Above 40 µm, more than 90 % is deposited (see Reference [6]). The dominant deposition mechanism of
this size of particles has been shown to be gravitational but air turbulence and electrostatic attraction
can also cause deposition (see Reference [7]). These deposited particles can be re-dispersed by walking
and cleaning actions, but not by air velocities associated with the cleanroom air. It is important that
these particles are removed by cleaning.
The presence and redistribution of particles >5 µm in cleanrooms is mostly related to human or
mechanical activity. In a cleanroom "at rest", there is likely to be little activity and dispersion of
particles, and the concentration of particles larger than 5 µm is close to zero with no significant particle
deposition. Therefore, it is only in the "operational" occupancy state that the particle deposition rate
should be considered.
The particle deposition rate is an attribute of a cleanroom or clean zone that determines the likely rate
of deposition of airborne particles onto cleanroom surfaces, such as product or process area. Using a
risk assessment, the acceptable amount of contamination of a vulnerable surface can be defined, and
the particle deposition rate can then be obtained that ensures that this amount of contamination is not
exceeded.
Methods of measuring the particle deposition rate in a cleanroom or clean zone are given in this
document. These are used during the operation of the cleanroom to ensure that the required particle
deposition rate is obtained, and for monitoring the cleanroom and clean zones to demonstrate
continuous control of airborne contamination. Monitoring the particle deposition rate also enables
PDR peaks to be correlated with activities so as to detect sources of contamination, and indicate what
changes are required to working procedures to reduce the contamination risk.
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
The particle deposition rate is the rate of deposition of particles onto surfaces over time, and can be
2
calculated as the change of particle surface concentration per m during the time of exposure in hours
and can be expressed as Formula (1):
CC−
fi
DD
R = (1)
D
tt−
fi
where
2
R is the deposition rate of particles equal to, or larger than D (µm) per m per hour;
D
2
C is the final particle surface concentration (number per m ) for particles equal to and larger
f
D
than D (µm);
2
C is the initial particle surface concentration (number per m ) for particles equal to and larger
i
D
than D (µm);
t is the final time of exposure (h);
f
t is the initial time of exposure (h).
i
If the particle deposition rate is determined on, or in close proximity to, a vulnerable surface, such as
product, then an estimate of the deposition of airborne particles onto the surface can be obtained by
applying Formula (2):
NR =⋅ta⋅ (2)
DD
where
N number of deposited particles larger than or equal to particle size D (µm);
D
t is the time the surface is exposed to particle deposition (h);
2
a is the surface area exposed to airborne contamination (m ).
Some industries use cleanrooms to manufacture optical instruments and components, such as mirrors,
lenses, and solar panels used in aerospace. The quality of these products is related to the amount of
light absorbed or reflected by particles on the surface. Therefore, this document also considers particle
obscuration rate of test surfaces exposed in cleanrooms in Annex C. Using the particle deposition rate
of various particle sizes, the particle obscuration rate of airborne particles depositing onto a surface
and obscuring light can be calculated and used in a similar way to the particle deposition rate to reduce
the risk of surface contamination.
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SIST EN ISO 14644-17:2021
INTERNATIONAL STANDARD ISO 14644-17:2021(E)
Cleanrooms and associated controlled environments —
Part 17:
Particle deposition rate applications
1 Scope
This document gives direction on the interpretation and application of the results of the measurement
of particle deposition rate on one or more vulnerable surfaces in a cleanroom as part of a contamination
control programme. It provides some instructions on how to influence the particle deposition rate and
reduce the risk of particle contamination on vulnerable surfaces.
This document gives information on how a cleanroom user can use the particle deposition rate
measurements to determine limits that can be set for macroparticles on vulnerable surfaces. It also
gives a risk assessment method by which an acceptable risk of deposition of particles onto vulnerable
surfaces in a cleanroom can be established and, when this is not achieved, methods that can be used to
reduce the particle deposition rate.
An alternative to the particle deposition rate is the particle obscuration rate which determines the rate
of increase of coverage of particles onto an area of surface over time. The particle obscuration rate can
be used in an analogous way to the particle deposition rate and the required particle obscuration rate
for a specified surface can be calculated and the risk from deposited particles reduced.
This document does not:
— provide a method to classify a cleanroom with respect to particle deposition rate or particle
obscuration rate;
— directly consider the deposition of microbe-carrying particles, although they can be treated as
particles;
— give any consideration to surface deposition by contact as, for example, when personnel touch a
product and contamination is transferred.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14644-3:2019, Cleanrooms and associated controlled environments — Part 3: Test methods
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 http:// www .electropedia .org/
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
3.1
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 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]
3.2
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 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) 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]
3.3
critical particle size
smallest particle size (3.7) that negatively impacts on product or process quality
3.4
critical location
location where a vulnerable surface (3.12) is exposed to particle contamination
3.5
operational
agreed condition where the cleanroom (3.1) or clean zone (3.2) is functioning in the specified manner,
with equipment operating and with the specified number of personnel present
[SOURCE: ISO 14644-1:2015, 3.3.3]
3.6
particle
minute piece of matter with defined physical boundaries
[SOURCE: ISO 14644-1:2015, 3.2.1]
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
3.7
particle size
diameter of a sphere or the diameter of a sphere (circle) that encompasses a non-spherical particle, or
an equivalent diameter
Note 1 to entry: The definition should be stated in relation to the measurement method.
Note 2 to entry: In ISO 14644-1, light scattering based detection is used. Other measurement methods yield
different size definitions (see A.1).
3.8
particle deposition rate
PDR
number of particles depositing onto a known surface area during a known time of exposure
2
Note 1 to entry: It is expressed in number per m per hour.
3.9
particle deposition rate level
PDRL
level of particle deposition rates (3.8) for a range of particle sizes (3.7)
3.10
particle obscuration rate
POR
rate of change of particle area coverage of a surface during time of exposure
3.11
test surface
surface of specific area and known surface cleanliness used to collect particles that deposit from the air
in a specified time
Note 1 to entry: A test surface is used in this document to determine the particle deposition rate (3.8).
Note 2 to entry: A test surface can be a witness plate or an integral part of a measuring instrument.
3.12
vulnerable surface
surface whose functionality diminishes when particles larger than the critical size are present
3.13
witness plate
clean flat plate of a specified surface area used to collect particles that deposit from the air in a
specified time
Note 1 to entry: A witness plate is exposed adjacent to a vulnerable surface (3.12) to obtain the particle deposition
rate that occurs at that location.
Note 2 to entry: A witness plate is not normally part of a measuring instrument and, after exposure, the witness
plate is taken to a measuring instrument for the counting and sizing of the particles deposited.
4 Symbols
2
a product area in m
2
A area of the silhouette of the observed particles (mm )
2
C particle concentration in number of particles ≥D µm per m
D
D particle size in micrometres
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
F particle obscuration rate
L particle deposition rate level
N number of particles ≥D µm deposited onto a surface
D
η efficiency of detection method
2 -2
O particle obscuration factor (in mm ·m )
2
R particle deposition rate in number of particles ≥D µm per m ·h
D
t time of exposure
5 Particle deposition rate methodology
5.1 General
Particle deposition rate data obtained in a cleanroom can be used to establish the probability of
airborne particles depositing onto a vulnerable surface during exposure and provide a methodology
that supports the required quality of a cleanroom during operation. The information in 5.2 and 5.3 gives
a method that can be used to establish the correct particle deposition rate cleanliness conditions in a
cleanroom and associated controlled environments. This information is used to demonstrate continued
control of these cleanliness conditions. ISO 14644-2 shall be considered as a guide for the development
and application of a monitoring plan.
5.2 Establishing the particle deposition rate required for control of particle deposition
on vulnerable surfaces
Establishing control of macroparticles in the controlled environment through use of the particle
deposition rate is required when a new facility is designed, or when cleanliness requirements are
changed in existing facilities. An assessment shall be made of the product attributes and the process
activities performed in the cleanroom. Based on this assessment, the required degree of control of
particle contamination shall be established using the following steps.
1) The surfaces in the cleanroom or associated controlled environments that are vulnerable to particle
deposition shall be identified. This can be done by considering the manufacturing carried out in
the cleanroom, the status of the technical installations, production equipment, and operational
procedures.
2) The smallest particle size that impacts on product or production quality on each vulnerable surface
(critical particle size) shall be determined.
NOTE 1 Differences in particle type (metallic vs non-metallic, transparent vs opaque, microbial vs non-
microbial) can lead to a particle-specific approach.
3) The maximum number of particles of the critical size that contaminates each vulnerable surface
considered shall be determined.
4) Knowing the maximum number of particles of a critical size that is acceptable on each surface, the
particle deposition rate or particle deposition rate level (see Table 1) at the critical particle size
shall be determined.
5) The critical surface with the tightest requirements on particle deposition rate and particle
deposition rate level will determine the particle deposition rate and particle deposition rate level
for the critical area.
6) After the maximum particle deposition rate or particle deposition rate level requirements are
defined for the critical area, the measurement method shall be chosen and put into operation. The
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SIST EN ISO 14644-17:2021
ISO 14644-17:2021(E)
method can be selected based on sensitivity, required measurement frequency, and other factors
such as ease of use. ISO 14644-3 can be consulted for information on measurement methods.
NOTE 2 Examples of the method
...
SLOVENSKI STANDARD
oSIST prEN ISO 14644-17:2020
01-marec-2020
Čiste sobe in podobna nadzorovana okolja - 17. del: Aplikacije glede hitrosti
usedanja delcev (ISO/DIS 14644-17:2019)
Cleanrooms and associated controlled environments - Part 17: Particle deposition rate
applications (ISO/DIS 14644-17:2019)
Reinräume und zugehörige Reinraumbereiche - Teil 17: Anwendungen zur
Partikelabscheidungsrate (ISO/DIS 14644-17:2019)
Salles propres et environnements maîtrisés apparentés - Partie 17: Applications de taux
de dépôt de particules (ISO/DIS 14644-17:2019)
Ta slovenski standard je istoveten z: prEN ISO 14644-17
ICS:
13.040.35 Brezprašni prostori in Cleanrooms and associated
povezana nadzorovana controlled environments
okolja
oSIST prEN ISO 14644-17:2020 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 14644-17:2020
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oSIST prEN ISO 14644-17:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 14644-17
ISO/TC 209 Secretariat: ANSI
Voting begins on: Voting terminates on:
2019-10-29 2020-01-21
Cleanrooms and associated controlled environments —
Part 17:
Particle deposition rate applications
Salles propres et environnements maîtrisés apparentés —
Partie 17: Applications de taux de dépôt de particules
ICS: 13.040.35
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 14644-17:2019(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2019
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oSIST prEN ISO 14644-17:2020
ISO/DIS 14644-17:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2019 – All rights reserved
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oSIST prEN ISO 14644-17:2020
ISO/DIS 14644-17:2019(E)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Particle deposition rate (PDR) . 3
4.1 General . 3
4.2 PDR for establishing contamination control in a cleanroom . 3
4.3 PDR for demonstrating continuous control of contamination . 4
5 Measurement of Particle Deposition Rate (PDR) . 4
6 Particle Deposition Rate Limits (PDRL) . 4
7 Documentation . 6
Annex A (informative) Measurement of PDR . 7
Annex B (informative) Examples of measurement of PDR and PDRL .10
Annex C (informative) Measurement of the particle obscuration .13
Annex D (informative) Relationship between PDR and airborne concentration of particles .16
Annex E (informative) Assessment and control of particle deposition .17
Bibliography .21
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ISO/DIS 14644-17:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO
collaborates closely with the International Electro technical Commission (IEC) on all matters of electro
technical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14644-17 was prepared by Technical Committee ISO/TC 209, Cleanrooms and associated controlled
environments in collaboration with Technical Committee CEN/TC 243, Cleanroom technology.
ISO 14644 consists of the following parts, under the general title Cleanrooms and associated controlled
environments:
Part 1: Classification of air cleanliness by particle concentration
Part 2: Monitoring to provide evidence of cleanroom performance related to air cleanliness by parti-
cle concentration
Part 3: Test methods
Part 4: Design, construction and start-up
Part 5: Operations
Part 7: Separative devices (clean air hoods, gloveboxes, isolators and mini-environments)
Part 8: Classification of air cleanliness by chemical concentration
Part 9: Classification of surface cleanliness by particle concentration
Part 10: Classification of surface cleanliness by chemical concentration
Part 12: Specification for monitoring air cleanliness by nanoscale particle concentration
Part 13: Cleaning of surfaces to achieve defined levels of cleanliness in terms of particle and chemical
classifications
Part 14: Assessment of suitability for use of equipment by airborne particle concentration
Part 15: Assessment of suitability for use of equipment and materials by airborne chemical con-
centration
Part 16: Energy efficiency in cleanrooms and clean air devices
Attention is also drawn to ISO 14698, Cleanrooms and associated controlled environments — Bio-
contamination control:
Part 1: General principles and methods
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Part 2: Evaluation and interpretation of biocontamination data
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Introduction
Cleanrooms and associated controlled environments are used to control contamination to levels
appropriate for accomplishing contamination-sensitive activities. Products and processes that benefit
from the control of contamination include those in industries such as aerospace, microelectronics,
optics, nuclear, food, healthcare, pharmaceuticals, and medical devices.
[1]
ISO 14644-1:2015 considers airborne particles in cleanrooms and classifies their cleanliness by
[2] [3]
maximum permitted concentrations, and both ISO 14644-9:2012 and IEST-STD-CC1246E consider
the concentration of surface particles. This ISO standard considers the rate of particle deposition
[4]
onto cleanroom surfaces and is based on VCCN Guideline 9. The particle deposition rate (PDR) is
important, as the probability of contamination by airborne particles onto vulnerable surfaces, such as
manufactured products, is directly related to the PDR.
[5]
In ISO 14644-3:2019 Test methods, there is an overview of methods for the determination of
deposition of particles, larger or equal to 0,1 µm. In this new standard, the focus is on the rate that
macroparticles larger than 5 µm deposit on surfaces, and the application of this information to
controlling contamination in cleanrooms.
Various sizes of particles are generated in cleanrooms by personnel, machinery, tools, and processes, and
distributed by air moving about the cleanroom. According to ISO 14644-1, cleanrooms and controlled
environments with a particle class of ISO 5, or cleaner, will contain zero or very low concentrations
of airborne particles larger than 5 µm. However, in operating cleanrooms, many more particles in the
size range of 5 µm to 500 µm, and greater, are found on surfaces than suggested by the classification
limits of the size of particles given in ISO 14644-1. The main reason for this is that these larger particles
are not detected in the air by particle counters because of deposition losses in sampling tubes, and
the entry to and within particle counters. Large particles cause contamination problems and their
presence and potential for deposition onto vulnerable surfaces is best determined by measuring the
particle deposition rate (PDR) onto surfaces.
Particles smaller than 5 µm are most likely to be removed from the cleanroom air by the ventilation
system, but for particles above 10 µm more than 50% will be removed from the air by surface deposition,
[6]
and above 40 µm more than 90% will be deposited. The dominant deposition mechanism of this size
of particles has been shown to be gravitational but air turbulence and electrostatic attraction may also
[7]
cause deposition. These deposited particles can be re-dispersed by walking and cleaning actions, but
not by air velocities associated with the cleanroom air. It is important that these particles are removed
by cleaning.
The presence and redistribution of particles > 5 µm in cleanrooms is mostly related to human or
mechanical activity. In a cleanroom ‘at rest’ there is likely to be little activity and dispersion of particles,
and the concentration of particles larger than 5 µm will be close to zero with no significant particle
deposition. Therefore, it is only in the ‘operational’ occupancy state that the PDR should be considered.
The PDR is an attribute of a cleanroom or clean zone that determines the likely rate of deposition of
airborne particles onto cleanroom surfaces, such as product or process area. Using a risk assessment,
the acceptable amount of contamination of a vulnerable surface can be defined, and the PDR required
for controlling the airborne contamination of the vulnerable surface obtained. Methods of measuring
the PDR in a cleanroom or clean zone are given in this standard. These are used during the operation of
the cleanroom to ensure that the required PDR is obtained, and for monitoring the cleanroom and clean
zones to demonstrate continuous control of airborne contamination. Monitoring the PDR also enables
PDR peaks to be correlated with activities so as to detect sources of contamination, and indicate what
changes are required to working procedures to reduce the contamination risk.
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The PDR is the rate of deposition of particles onto surfaces over time, and can be calculated as the
2
change of particle surface concentration per m during the time of exposure in hours and can be
expressed as follows:
PDR = (C - C ) / (t - t) (1)
f i i
where,
2
PDR is the deposition rate per m per hour of particles equal to, or larger than, a considered size
in micrometres,
2
C is the final particle surface concentration (number/m ),
f
2
C is the initial particle surface concentration (number/m ),
i
t is the final time of exposure (hours),
t is the initial time of exposure (hours).
i
In this standard the PDR is applied to cumulative particle sizes (≥ D) and the following notation used:
PDR
D
where, D is the particle size (µm).
If the PDR is determined at a location, or in close proximity to a vulnerable surface, such as product,
then an estimate of the deposition of airborne particles onto the surface can be obtained by applying
the following Formula:
Number of deposited particle (≥D) = PDR . t .a (2)
D
where,
2
PDR is particle deposition rate (number/m /hour),
D
t is the time the surface is exposed to particle deposition (hours),
2
a is the surface area exposed to airborne contamination (m ).
Some industries use cleanrooms to manufacture optical instruments and components, such as mirrors,
lenses, and solar panels used in aerospace. The quality of these products is related to the amount of
light absorbed or reflected by particles on the surface. Therefore this standard also considers particle
obscuration rate (POR) of test surfaces exposed in cleanrooms in Annex C. Using the PDR of various
particle sizes, the POR of airborne particles depositing onto a surface and obscuring light can be
calculated and used in a similar way to the PDR to reduce the risk of surface contamination.
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oSIST prEN ISO 14644-17:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 14644-17:2019(E)
Cleanrooms and associated controlled environments —
Part 17:
Particle deposition rate applications
1 Scope
This part of the ISO 14644 standards gives guidance on the interpretation and application of the
results of the measurement of Particle Deposition Rate (PDR) on one, or more vulnerable surfaces
in a cleanroom as part of a contamination control programme. It provides some guidance on how to
influence the PDR and reduce the risk of particle contamination on vulnerable surfaces.
This standard gives information on how a cleanroom user can use the PDR measurements to determine
limits that can be set for macroparticles on vulnerable surfaces. It also gives a risk assessment method
by which an acceptable risk of deposition of particles onto vulnerable surfaces in a cleanroom can be
established and, when this is not achieved, methods that can be used to reduce the PDR.
Note to entry: An alternative to the PDR is the particle obscuration rate which determines the rate of
increase of coverage of particles onto an area of surface over time. The POR can be used in an analogous
way to the PDR and the required POR for a specified surface can be calculated and the risk from
deposited particles reduced.
This standard does not:
• provide a method to classify a cleanroom with respect to PDR or POR,
• directly consider the deposition of microbe-carrying particles (MCPs), although MCPs can be treated
as particles,
• give any consideration to surface deposition by contact as, for example, when personnel touch a
product and contamination is transferred.
2 Normative references
The following document, in whole or in part, is normatively referenced in this standard and is
indispensable for its application. The latest edition of the document (including any amendments)
applies.
ISO 14644-3, Cleanrooms and associated controlled environments – Part 3: Test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. Where a term has been
defined in ISO 14644, that definition is normally used.
3.1
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.
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Note 2 to entry: Levels of other cleanliness attributes such as chemical, viable or nanoscale 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]
3.2
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 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 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]
3.3
critical particle size
smallest particle size that can have a negative impact on the observed vulnerable surface.
3.4
critical location
location where a vulnerable surface is exposed to airborne deposition of particles.
3.5
operational
condition where the cleanroom or clean zone is functioning in the specified manner, with equipment
operating and with the specified number of personnel present.
[SOURCE: ISO 14644-1:2015, 3.3.3 operational occupancy state]
3.6
particle
minute piece of matter with defined physical boundaries
[SOURCE: ISO 14644-1:2015, 3.2.1]
3.7
particle size
diameter of a sphere or the diameter of circumferential sphere (circle) around a non-spherical particle,
or an equivalent diameter determined by the measurement method used.
[SOURCE: ISO 14644-1:2015, 3.2.2 modified]
Note 1 to entry: The definition should be stated in relation to the measurement method.
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3.8
test surface
surface of specific surface area and known surface cleanliness used to collect particles that deposit
from the air in a specified time.
Note 1 to entry: A test surface is used in this standard to determine the PDR
Note 2 to entry: A test surface can be a witness plate or an integral part of a measuring instrument.
3.9
witness plate
clean flat plate of a specified surface area used to collect particles that deposit from the air in a
specified time.
Note 1 to entry: A witness plate is exposed adjacent to a vulnerable surface to obtain the PDR that occurs at that
location.
Note 2 to entry: A witness plate is not normally part of a measuring instrument and, after exposure, the witness
plate is taken to a measuring instrument for the counting and sizing of the particles deposited.
4 Particle deposition rate (PDR)
4.1 General
PDR data obtained in a cleanroom can be used to establish the probability of airborne particles
depositing onto a vulnerable surface during exposure and provide a system that supports the required
quality of a cleanroom during operation. The information in the following sections give a method on
how the PDR shall be used to establish the correct PDR cleanliness conditions in a cleanroom and
associated controlled environments, and is used to demonstrate continued control of these cleanliness
conditions.
4.2 PDR for establishing contamination control in a cleanroom
Establishing control of the air cleanliness through use of the PDR is required when a new facility is
designed, or when cleanliness requirements are changed in existing facilities. An assessment shall be
made of the type of cleanroom manufacturing carried out in the cleanroom. Based on the application,
the required degree of control of particle contamination shall be established using the following steps:
1) The surfaces in the cleanroom or associated controlled environments that are vulnerable to particle
deposition shall be determined. This can be established by consideration of the manufacturing
carried out in the cleanroom, the status of the technical installations, production equipment, and
operational procedures.
2) The smallest particle size that impacts on product or production quality in each vulnerable surface
shall be established. This shall be called the ‘critical’ particle size.
NOTE differences in particle type (metallic vs non-metallic, transparent vs opaque, microbial vs non-
microbial) may lead to a particle-specific approach.
3) The maximum number of particles of the critical size that causes contamination problems on each
vulnerable surface considered shall be established.
4) Knowing the maximum number of particles of a critical size that is acceptable on each surface, the
PDR limits at the critical particle size shall be determined. The use of Annex E shall be considered,
which gives information on a method to determine PDR from the maximum number of particles,
surface area and time that the vulnerable surface is exposed to airborne contamination.
5) Using the PDR requirements for each vulnerable surface, the maximum allowable PDR, which is the
PDR limit (PDRL) shall be obtained from Table 1.
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6) After the maximum PDR requirements are defined, the measurement method shall be chosen and
put into operation. The selection of the method can be based on sensitivity, required measurement
frequency, and other factors such as ease of use. ISO 14644-3: Test methods can be consulted for
information on measurement methods.
4.3 PDR for demonstrating continuous control of contamination
Demonstrating control of the PDR in a cleanroom over time is important to ensure that the quality of
the facility remains constant. It is necessary to demonstrate control of the PDR by demonstrating that
the required PDR limits continue to be achieved. Monitoring shall be carried out at the locations where
the most vulnerable surfaces are located, or at a location that is in close proximity and representative of
the location of the vulnerable surface.
The required frequency of monitoring shall be determined by the criticality of the product being
manufactured and the measuring equipment available (see Clause 6).
Failure to achieve the required PDR limit shall initiate an improvement of working, cleaning, and
maintenance procedures. If needed, changes in manufacturing equipment, or cleanroom design and
ventilation can be implemented. Methods of reducing the risk of airborne contamination are discussed
in Annex E.
5 Measurement of Particle Deposition Rate (PDR)
The method of measuring the PDR is based on the collection of particles onto a test surface of a known
surface area over a known time period. The PDR is then calculated by use of Formula 1.
The PDR shall be measured at a vulnerable surface, or in close proximity to the vulnerable surface,
during the manufacturing carried out in the cleanroom. If required, the PDR can be measured at several
locations. The result of the measurement can then be used to check whether the location complies with
a specified maximum PDR, or maximum PDRL, for certain cumulative particle sizes.
The methods for collecting airborne particles onto a surface, sizing and counting these particles,
[5]
can be chosen with reference to ISO 14644-3: Test methods. Additional information is available
[8] [9] [10]
in ASTM E2088, ASTM 25 and ASTM F50. When choosing the counting and sizing apparatus,
consideration shall be given to the detection of particles in the relevant size range. The area of the test
surface also needs consideration, as if the PDR needs to be measured within a restricted time, the test
surface shall be large enough.
The witness plate, or measuring instrument, shall be placed in the same plane, and as close as possible
to the vulnerable surface. The test surface shall be at the same electrical potential. Counting and sizing
of particles collected on the test surface is carried out in a manner to obtain reproducible data and used
to obtain the PDR adjacent to the vulnerable surface being investigated.
Sampling shall only be carried out during manufacturing when the product or process is exposed to
airborne contamination. The minimum expected count for the largest critical particle size under
consideration shall not be less than 1, but desirably 5. If insufficient particles have been counted, the
time for measuring the PDR during the manufacturing of products or process shall be extended to
obtain a higher numbers of particles. It may be necessary to measure more than one manufacturing
period. A method of calculating the sample time is given in Annex A4. If a suitable sample is not feasible,
alternative measurement techniques shall be considered.
6 Particle Deposition Rate Limits (PDRL)
To establish and maintain control of the particle contamination by surface deposition required
for vulnerable surfaces, it is necessary to set limits of PDR that shall not be exceeded. The PDR limit
depends on the acceptable surface contamination, which can be determined by a risk assessment. The
PDR limit is determined by the acceptable particle contamination, the vulnerable surface area, the
critical particle size and the expected time of exposure (see Annex B3).
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The Particle Deposition Rate Limits (PDRLs) that shall not be exceeded over a range of cumulative
particle sizes are calculated from Formula (3). Formula (3) is based on typical distributions found
in cleanrooms that give PDRs over a range of cumulative sizes of macroparticles, and show that PDR
[11]
is in direct proportion to the cumulative particle size. A typical size distribution is shown later in
Figure B3. The formula is also based on the method of setting particle limits given in ISO 14644-9 but
the reference particle size is changed in this standard to ≥10µm.
PDRL = PDR D/10 (3)
D *
where
D is the observed particle size (µm),
2
PDR is the number of particles ≥ D µm per m per hour.
D
Given in Table 1 are examples of PDRLs over a range of different cleanliness levels. If required,
intermediate limits can be used.
Should the PDR for different size of particles at intermediate levels of PDRL be required, the following
equation can be used:
10*PDRL
PDR = (4)
D
D
Should the PDR be needed at another particle size for the same PDRL, as can occur when instruments
that measure PDR do not do so at the required particle size, then t
...
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