EN 16602-70-54:2019

SLOVENSKI STANDARD
01-maj-2019
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Space product assurance - Ultracleaning of flight hardware
Raumfahrtproduktsicherung - Ultra-Reinigung von Flug-Hardware
Assurance produit des projets spatiaux - Ultra nettoyage des matériels de vol
Ta slovenski standard je istoveten z: EN 16602-70-54:2019
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 16602-70-54
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2019
ICS 49.140
English version
Space product assurance - Ultracleaning of flight hardware
Assurance produit des projets spatiaux - Raumfahrtproduktsicherung - Ultra-Reinigung von
Ultranettoyage des matériels de vol Flug-Hardware
This European Standard was approved by CEN on 9 November 2018.

CEN and CENELEC 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 and CENELEC 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 and CENELEC member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2019 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. EN 16602-70-54:2019 E
reserved worldwide for CEN national Members and for
CENELEC Members.
EN16602-70-54:2019 (E)
Table of contents
European Foreword . 7
Introduction . 8
1 Scope . 9
2 Normative references . 10
3 Terms, definitions and abbreviated terms . 11
3.1 Terms from other standards . 11
3.2 Terms specific to the present standard . 11
3.3 Abbreviated terms. 13
3.4 Nomenclature . 13
4 Principles . 15
4.1 Cleaning techniques: Contamination removal . 15
4.1.1 Introduction . 15
4.1.2 Ultracleaning . 18
4.1.3 Cleaning principles . 19
4.1.4 Trade-off process . 20
4.1.5 Selection of an end-to-end cleaning process . 21
5 Requirements . 23
5.1 Specifying process . 23
5.1.1 General . 23
5.1.2 Specifying process means . 23
5.2 Definition of end-to-end cleaning process . 24
5.2.1 Test samples . 24
5.2.2 Definition of critical contamination and tracers . 24
5.2.3 Application process for critical contaminants and tracers . 25
5.2.4 Selection of analytical techniques . 26
5.2.5 Definition of test matrix . 26
5.2.6 Cleaning processes . 26
5.2.7 Cleaning efficacy . 27
5.3 Validation of end-to-end cleaning process . 29
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5.4 Packaging, containerization, transportation, storage . 31
(normative) Request for ultracleaning - DRD . 32
A.1 DRD identification . 32
A.2 Purpose and objective . 32
A.3 Expected response . 32
A.3.1 Scope and content . 32
A.3.2 Special remarks . 32
(normative) Ultracleaning work proposal - DRD. 33
B.1 DRD identification . 33
B.2 Purpose and objective . 33
B.3 Expected response . 33
B.3.1 Scope and content . 33
B.3.2 Special remarks . 34
(normative) Ultracleaning process report - DRD . 35
C.1 DRD identification . 35
C.2 Purpose and objective . 35
C.3 Expected response . 35
C.3.1 Scope and content . 35
C.3.2 Special remarks . 36
(informative) Good cleanability design guidelines . 37
D.1 Conception and design guidelines . 37
D.1.1 General . 37
D.1.2 Corners and edges. 38
D.1.3 Weld seams at corners and edges . 39
D.1.4 Transitions . 40
D.1.5 Fixed/separable joins: . 40
(informative) Cleaning techniques . 42
E.1 Blasting cleaning techniques . 42
E.1.1 Compressed air blasting. 42
E.1.2 Wet compressed air blasting . 42
E.1.3 Pressurized fluid blasting . 43
E.1.4 Low-pressure water jet blasting . 43
E.1.5 Elutriation blasting . 44
E.1.6 Centrifugal blasting . 44
E.1.7 Steam blasting . 45
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E.1.8 CO pellet cleaning . 45
E.1.9 Accelerated CO snow cleaning . 46
E.2 Mechanical cleaning . 47
E.2.1 Wiping . 47
E.2.2 Brushing and sweeping . 48
E.2.3 Scraping and abrading . 48
E.2.4 Grinding . 49
E.2.5 Beating off . 49
E.3 Fluidic cleaning . 50
E.3.1 Washing and rinsing . 50
E.3.2 Blowing off cleaning . 50
E.3.3 Suction cleaning . 51
E.3.4 Ultrasonic cleaning . 51
E.4 Chemical cleaning . 52
E.4.1 General principle of chemical cleaning . 52
E.4.2 Etching and leaching . 52
E.4.3 Chemical reaction . 52
E.5 Solvent cleaning . 53
E.5.1 Detaching and stripping . 53
E.6 Thermal cleaning . 53
E.6.1 General principle of thermal cleaning . 53
E.6.2 Evaporating . 53
E.6.3 Scarfing . 54
E.6.4 Decomposing . 54
E.7 Special cleaning . 55
E.7.1 Hot vacuum purge . 55
purge . 55
E.7.2 Hot N2
E.7.3 Plasma Chamber cleaning . 56
E.7.4 UV-light cleaning . 56
E.7.5 LASER beam cleaning . 57
E.7.6 Supercritical CO Cleaning . 57
E.7.7 Liquid Peel Cleaning . 58
(informative) Contamination detection techniques . 59
F.1 Particulate contamination . 59
F.1.1 General . 59
F.1.2 Assessment matrix . 59
F.2 Chemical molecular contamination . 63
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F.3 Microbiological contamination . 63
(informative) Witness sample design . 64
G.1 Example witness sample design . 64
(informative) Examples for cleanliness classification . 65
H.1 Particles . 65
H.1.1 Classification system . 65
H.1.2 Examples for cleaning efficacy . 66
H.2 Molecular contamination . 67
H.2.1 Classification system . 67
H.2.2 Examples for cleaning efficacy . 67
Bibliography . 69

Figures
Figure 4-1: Typical types of molecular and particulate contamination . 15
Figure 4-2: Relationship between van der Waals force and weight in dependence upon
particle diameter (model according to Hamaker for Al particles on Al
substrate) . 16
Figure 4-3: Influences on the cleaning efficacy . 17
Figure 4-4: Available cleaning principles and related techniques . 19
Figure 4-5: Two stage trade-off method . 20
Figure 4-6: Logic flow for the selection and optimisation of an end-to-end cleaning
process for hardware. 22
Figure 5-1: Cleanliness validation logic for using witness plates . 30
Figure 5-2: Cleanliness validation logic for using products or components . 30

: Design of corners and edges . 39
: Material transitions joined by a weld seam . 40
: Materials joined by a weld seam . 40
: Test sample geometry to assess the cleaning efficacy of a certain cleaning
technique (left) and composition of the test sample surface (right) . 64

Tables
Table 4-1: Typical cleanliness levels and their verification techniques on spacecraft
surfaces . 18

Table F-1 : Comparison of different direct particle detection methods . 62
Table H-1 : Selected SCP classes for cleanrooms and associated controlled
environments . 65
EN16602-70-54:2019 (E)
Table H-2 : Examples of cleaning efficacies on different substrates . 66
Table H-3 : Overview of ISO SCC molecular contamination classes . 67
Table H-4 : Examples of cleaning efficacies on different substrates . 67

EN16602-70-54:2019 (E)
European Foreword
This document (EN16602-70-54:2019) has been prepared by Technical
Committee CEN-CENELEC/TC 5 “Space”, the secretariat of which is held by
DIN.
This standard (EN16602-70-54:2019) originates from ECSS-Q-ST-70-54C.
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 September
2019, and conflicting national standards shall be withdrawn at the latest by
September 2019.
Attention is drawn to the possibility that some of the elements of this document
may be the subject of patent rights. CEN [and/or CENELEC] shall not be held
responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request given to
CEN by the European Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has
therefore precedence over any EN covering the same scope but with a wider
domain of applicability (e.g. : aerospace).
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, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
EN16602-70-54:2019 (E)
Introduction
This ECSS Standard describes the procedures to be used to clean to a level of
cleanliness beyond the scope of the ECSS-Q-ST-70-01, and to control the
cleanliness level of flight hardware prior to and following a posteriori to the
application of the ultracleaning process. The intended objective of the
ultracleaning process is to remove all surface contamination (particulates,
biologic material cell debris and chemical molecular contamination) on flight
hardware, with no specific limit in geometric dimension or contamination
levels. This includes removal of biological material for avoidance of false
positive results during investigation of extra-terrestrial samples or
environments.
EN16602-70-54:2019 (E)
Scope
This standard addresses process descriptions, process validation, cleanliness
control and monitoring, recontamination prevention, quality assurance as follows:
PROCESSES DESCRIPTIONS, including
 Detergent cleaning
 Alcohol cleaning
 Ultrapure water cleaning
 Liquid boundary layer disruption cleaning
 Multiple solvent cleaning (JPL procedure)
 Vacuum bakeout
 Supercritical fluids cleaning
 Carbon dioxide snow cleaning
 Plasma cleaning
 Pyrolysis
 Criteria for selecting other/novel processes
PROCESS VALIDATION
 Test material selection
 Preparation of test materials for process application
 Deposition of contaminants
 Description of test conditions
 Verification of cleanliness level
CLEANLINESS CONTROL AND MONITORING, including
 Micro/nano imaging techniques
 Spectrometry techniques
 Spectroscopy techniques
 Chromatography techniques
RECONTAMINATION PREVENTION
 Packaging systems
 Protective covers
 Storage
QUALITY ASSURANCE
This standard may be tailored for the specific characteristic and constrains of a
space project in conformance with ECSS-S-ST-00.
EN16602-70-54:2019 (E)
Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revision of any of these publications
do not apply. However, parties to agreements based on this ECSS Standard are
encouraged to investigate the possibility of applying the more recent editions of
the normative documents indicated below. For undated references, the latest
edition of the publication referred to applies.

EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS system - Glossary of terms
EN 16602-10-09 ECSS-Q-ST-10-09 Space product assurance - Nonconformance control
system
EN 16602-20-08 ECSS-Q-ST-20-08 Space product assurance - Storage, handling and
transportation of spacecraft hardware
EN 16602-70 ECSS-Q-ST-70 Space product assurance - Materials, mechanical parts
and processes
EN 16602-70-01 ECSS-Q-ST-70-01 Space product assurance - Cleanliness and
contamination control
ISO 14644-9: 2012 Cleanrooms and associated controlled environments -
Part 9: Classification of surface cleanliness by particle
concentration
ISO 14644-10: 2013 Cleanrooms and associated controlled environments -
Part 10: Classification of surface cleanliness by
chemical concentration
EN16602-70-54:2019 (E)
Terms, definitions and abbreviated terms
3.1 Terms from other standards
a. For the purpose of this Standard, the terms and definitions from ECSS-S-
ST-00-01 apply, in particular for the following terms:
1. cleanliness
2. qualification
3. test
4. validation
5. verification
b. For the purpose of this Standard, the terms and definitions from ECSS-Q-
ST-70-01 apply, in particular for the following terms:
1. cleanroom
2. off-gassing
3.2 Terms specific to the present standard
3.2.1 bioaerosol
dispersed biological agents in a gaseous environment
[ISO 14698-1:2003]
3.2.2 biological contamination
contamination of materials, devices, individuals, surfaces, liquids, gases or air
with viable particles.
NOTE 1 Depending on the context, biological
contamination can be considered as
organic or as particulate
contamination. A bacterial cell has
about 1E-13 g (organic content of
one cell is below the detection limit
of most chemical methods).
NOTE 2 Problem is that, apart from growing,
cells and spores often have
EN16602-70-54:2019 (E)
extracellular material that can be
more mass than the cell itself.
3.2.3 cleanliness (of a solid surface)
condition of a solid surface where the amount of contamination is controlled to
a specific level
NOTE Example of amount of contamination include
particle, chemical molecular or viable
3.2.4 contaminant
any particulate, chemical molecular, non-particulate and biological entity that
can adversely affect the product or process
3.2.5 decontamination
reduction of unwanted matter to a defined level
3.2.6 direct measurement method (DMM)
measurement method where the contamination that is to be determined is
being assessed without any intermediate steps
[adapted from ISO 14644-9:2012]
3.2.7 indirect measurement method (IMM)
measurement method where the contamination that is to be determined is
being assessed with intermediate steps
[adapted from ISO 14644-9:2012]
3.2.8 surface cleanliness of chemicals (SCC)
presence on the surface of a product or instrument of molecular, chemical, non-
particulate, species in the adsorbed or deposited state which can have a
deleterious effect on the product, process or equipment in the cleanroom or
controlled environment
[adapted from ISO 14644-10:2013]
3.2.9 surface cleanliness of particles (SCP)
class of surface particle cleanliness is a grading number stating the maximum
allowable surface concentration, in particles per m², for a considered size of
particles, SPC Classes 1 to 8
[adapted from ISO 14644-9:2012]
3.2.10 surface cleanliness particles (SCP) classification
level (or the process of specifying or determining the level) that represents
maximum allowable surface concentrations, in particles per square metre, for
considered sizes of particles, expressed in terms of an ISO SCP Class N
[ISO 14644-9:2012]
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3.2.11 surface particle concentration
number of individual particles per unit of surface area under consideration
[ISO 14644-9:2012]
3.2.12 thin film contamination
layers of critical contaminants that range from the nanometre scale to the
micrometre scale
3.2.13 viable particle
particle that consists of, or supports, one or more live microorganisms
3.2.14 cleaning efficacy
removal of specific contaminants from a surface by a cleaning process,
determined by the final accomplished surface cleanliness, in respect to the
initial surface cleanliness
NOTE 1 Cleaning efficacy can be expressed
in absolute (surface concentration) or
relative (percentage) terms.
NOTE 2 In general, repetitive application of
the same cleaning process results in
consecutive decreasing efficacy.
3.3 Abbreviated terms
For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01
and the following apply:
Abbreviation Meaning
document requirements definition
DRD
-6
parts per million (10 )
ppm
3.4 Nomenclature
The following nomenclature applies throughout this document:
a. The word “shall” is used in this Standard to express requirements. All
the requirements are expressed with the word “shall”.
b. The word “should” is used in this Standard to express recommendations.
All the recommendations are expressed with the word “should”.
NOTE It is expected that, during tailoring,
recommendations in this document are either
converted into requirements or tailored out.
c. The words “may” and “need not” are used in this Standard to express
positive and negative permissions, respectively. All the positive
EN16602-70-54:2019 (E)
permissions are expressed with the word “may”. All the negative
permissions are expressed with the words “need not”.
d. The word “can” is used in this Standard to express capabilities or
possibilities, and therefore, if not accompanied by one of the previous
words, it implies descriptive text.
NOTE In ECSS “may” and “can” have completely
different meanings: “may” is normative
(permission), and “can” is descriptive.
e. The present and past tenses are used in this Standard to express
statements of fact, and therefore they imply descriptive text.
EN16602-70-54:2019 (E)
Principles
4.1 Cleaning techniques: Contamination removal
4.1.1 Introduction
In the simplest case contamination can be defined as foreign matter, but in
relation to this standard is considered any particulate, chemical molecular, non-
particulate and biological entity on a surface that can adversely affect the
product or process. Increase of contamination leads generally to cumulative
build-up.
Surface contamination, such as particles in the micrometre range,
microbiological contamination or airborne and surface molecular
contamination, has become a significant hazard in many areas of industry.
Figure 4-1 shows schematically typical types of molecular and particulate
contamination.
abiotic & inorganic
 manufacturing process residues (dust from abrasive
processes, abrading agents, …)
 dust from the environment
 extraterrestrial samples
 etc.
biotic
 bacteria
 spores
 flakes of skin & cell fragments
 etc.
filmic (organic & anorganic)
 residues from auxiliary production materials (cooling
lubricants, preserving agents, …)
 fingerprints
 etc.
Figure 4-1: Typical types of molecular and particulate contamination
Molecular Particles
≡
Ratio van der Waals' forces / particle weight
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The deposition of contamination on surfaces for example occurs in the
following three steps:
• Aerodynamic transportation to the boundary layer
• Transportation inside the boundary layer
• Contamination coming in contact with the surface
Contamination in the micro- and nanometre range can lead to the failure of
complete units, impairment of performance, or incorrect test results. Therefore,
for many applications, it is essential to ensure that contamination is reliably
kept away from component surfaces.
This objective is not easy to achieve, especially if one considers particles smaller
than 10 µm. These particles adhere to a surface through very strong bonding
interactions: covalent bonding, ionic bonding, van der Waals forces, hydrogen
bonding, dipole-dipole and electrostatic interactions, or a combination of these.
By using model approaches, the attractive and adhesive forces occurring
between particles and surfaces can be theoretically calculated. The calculations
deviate slightly from reality but if, for example, the magnitude of only the van
der Waals force is compared with particle weight, essential information about
the magnitude of the forces of attraction can still be obtained (see Figure 4-2).
Particle diameter in m
1,00E-07 1,00E-06 1,00E-05 1,00E-04 1,00E-03
1,00E+08
1,00E+07
1,00E+06
1,00E+05
1,00E+04
1,00E+03
1,00E+02
1,00E+01
1,00E+00
Figure 4-2: Relationship between van der Waals force and weight in dependence
upon particle diameter (model according to Hamaker for Al particles on Al
substrate)
Van der Waals force exceeds particle weight by a factor of 10 for particles of
diameter 0,5 µm. Relationships are especially pronounced in the case of small
particle diameters (particle diameter of < 10 µm). Whereas van der Waals forces
are linearly dependent upon the diameter over several orders of magnitude,
particle diameter is cubic to weight.
EN16602-70-54:2019 (E)
As the adhesive forces of particles on surfaces are the decisive parameters for
cleaning surfaces in contamination-sensitive areas, the choice of cleaning
method therefore plays a crucial role.
NOTE The theoretical forces of adhesion are
proportional to particle size, while the removal
forces varies between the second or third power
to the particle diameter thus requiring an
increasingly larger force to overcome the
adhesion force between the particle and the
substrate as the particle size is reduced
At sufficiently thick chemical molecular contamination layers the contaminants
will exhibit bulk-like characteristics where the required energy for removal is
independent of layer thickness. At low levels (e.g. few molecular layers) the
surface of the substrate becomes a significant factor and an increasing amount
of energy is required for removal. Consequently it becomes also increasingly
difficult to maintain surface cleanliness.
Cleaning principles and related techniques are described in more detail in
clause 4.1.3. In general, there are four parameters that influence the cleaning
efficacy: Chemical, mechanical, temperature and time. These factors are all
inter-correlated, i.e. the change of one factor has an influence on the others. For
example the reduction of temperature can be compensated by increase in
cleaning time or more aggressive cleaning. This is not limited to the type of
cleaning process alone, but also to type of contamination, surface characteristics
and process parameters (Figure 4-3).
Time Temperature
Mechanical Chemical
Figure 4-3: Influences on the cleaning efficacy
EN16602-70-54:2019 (E)
4.1.2 Ultracleaning
Table 4-1 shows typical cleanliness levels and their verification techniques for
precision cleaning of space hardware. This is considered a coarse summary of
what can be typically achieved. In practice, better or worse performance is
possible depending on the surfaces to be cleaned and methodological
differences in cleanliness verification.
Table 4-1: Typical cleanliness levels and their verification techniques on spacecraft
surfaces
Typical limits of verification
Cleaning
Cleanliness verification
process
Particles Molecular Bio
2 *
Visible, unaided eye * 300 ppm * 1E-06 g/cm n.a.
Witness plates
Precision
cleaning 2
Particles: PFO (ECSS-Q-ST-70-50) 20-50 ppm 2-3E-08 g/cm n.a.
Molecular: FTIR (ECSS-Q-ST-70-05)
* This method is not considered quantitative, the achievable cleanliness levels are indicative and depend on
type of illumination, viewing angle and distance, type of contamination and surface, and can be operator
dependent.
In the context of ultracleaning, the quantitative limit for cleanliness level is
considered below that provided in Table 4-1. It is possible that at very low
levels, the three different classes of contamination cannot anymore be clearly
discriminated, e.g.:
• Bioburden can contribute significantly to molecular contamination
• Bioburden can be considered a particle in size significantly below the
traditional µm range
• Bioburden is often associated with particles, and PFO measurements may
show a correlation with bioburden
• The morphology of molecular contamination can exhibit particulate-like
character
• A procedure to remove the performance driving single class can
inherently cover the others
There is no clear discrimination between precision and ultracleaning, in the
context of this standard, the term ultracleaning applies when traditional
methods are insufficient.
EN16602-70-54:2019 (E)
4.1.3 Cleaning principles
The cleaning principles that are currently available can be broadly split in to 6
general groups based on the type of cleaning action (Figure 4-4 and Annex E)
and include the following examples:
• Blasting Cleaning, this includes such methods as sand-blasting and
water blasting where a material is impinged on to the surface to be
cleaned (Annex E.1).
• Mechanical Cleaning, this includes wiping and brushing where another
physical surface is worked against the surface to be cleaned (Annex E.2).
• Fluidics Cleaning, this includes washing, and ultrasonic cleaning where
the surface to be cleaned is fully immersed in a cleaning fluid (Annex
E.3).
• Chemical Cleaning, this includes etching and leaching where the
material to be removed is dissolved in a solvent (Annex E.4).
• Solvent Cleaning, this includes detaching and stripping where the
chemical action removes the surface contaminant (Annex E.5).
• Thermal Cleaning, this includes evaporating and annealing where an
application of heat can affect contaminant removal (Annex E.6).
• Special Cleaning (not completely classifiable in the so far mentioned
conventional procedures), this includes Plasma Chamber cleaning; UV-
light cleaning; LASER cleaning; hot vacuum purge and Supercritical CO2
(Annex E.7).
BLASTING MECHANICAL FLUIDICS CHEMICAL SOLVENT THERMAL SPECIAL
CLEANING CLEANING CLEANING CLEANING CLEANING CLEANING CLEANING
• Compressed air blasting
• Wiping • Washing/Rinsing • Detaching & • Evaporating • Hot vacuum
• Etching &
Leaching Stripping purge
• Wet compressed air blasting
• Brushing, Sweeping • Blowing off
• Scarfing
cleaning
• Chemical • Plasma
• Pressurized fluid blasting
• Scraping/Abrading
• Decomposing
reaction
• Suction cleaning • UV light
• Low pressure water jet
• Grinding
blasting
• Ultrasonic
• LASER
• Beating off
cleaning
• Elutriation blasting
• Supercritical
CO
• Centrifugal blasting 2
• Steam blasting
• CO pellet cleaning
• CO2 snow cleaning
Figure 4-4: Available cleaning principles and related techniques
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4.1.4 Trade-off process
A trade-off is used (see Figure 4-5) that considers all current cleaning
techniques to derive an end-to-end process being optimised to clean hardware.
CLEANING PRINCIPLES
(see Figure 4-4)
st
1 STAGE
METHOD TRADE
OFF MATRIX
PRE-CLEANING
PACKING
METHODS
METHOD
TRADE-OFF
MAIN CLEANING
METHODS
nd
2 STAGE
POST CLEANING
PROCESS
METHODS
OPTIMISATION
RECOMMENDED
END-TO-END
PROCESS
Figure 4-5: Two stage trade-off method
The trade-off approach takes into account both methods and processes where a
cleaning method is one stage of an end-to-end process consisting of the
following process stages:
• PRE-cleaning method
• MAIN-cleaning method
• POST-cleaning method
• PACKAGING method
The first stage of the trade-off considers a large number of cleaning methods
and conduct an initial broad analysis by means of a trade-off matrix. The
analysis also identifies the suitability of these methods to PRE-cleaning, MAIN-
cleaning and POST-cleaning. Depending on the case, it is possible not to apply
all process stages. For example a simple case can lead to the application of only
the main or pre plus main or main plus post process stages.
Based on the results of the first stage, the second stage considers the
PACKAGING method and a smaller number of end-to-end cleaning processes
with the objective of optimising these processes to suit the needs of the cleaning
hardware.
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4.1.5 Selection of an end-to-end cleaning process
Figure 4-6 shows a logic flow for an end-to-end cleaning process for hardware.
This logic flow has been optimised based on the analysis and results of the 1st
stage trade-off matrix and the PACKAGING method trade-off and fully takes
into account all considerations of the end-to-end process, i.e.:
• PRE-cleaning method
• MAIN-cleaning method
• POST-cleaning method
• PACKAGING method
The logic flow for the PRE-cleaning is determined by whether the Flight
Hardware can be immersed in liquid. PRE-cleaning methods that immerse the
flight hardware in a liquid are preferred to non-immersive methods due to their
particulate efficacy and in some cases organic efficacy as well.
Any cleaning method needs to take into account the type of contaminant(s)
which need to be removed, and the material or hardware compatibility with
any intended process. A PRE-clean may be needed to remove gross
contamination but this can be achieved by wiping (wet or dry). The decision
whether to have a POST-cleaning is determined by whether the PRE-clean and
MAIN-clean left (or introduced) organic residue.
For the PACKAGING the method used depends on the duration of storage,
level of off-gassing material in Flight Hardware and whether the Flight
Hardware to be transported.
For long-term storage and transport there are 4 alternatives. The best option is a
low off-gassing Transport Box followed closely by a Sealed Box with Argon.
The use of an ultrapure N2 purged box is best used if there is the possibility of
organic recontamination due to the unavoidable use materials in the flight
hardware that can off-gas over a long period (typically 2 years).
For short term storage, typically less than 5 days (e.g. temporary storage prior
to assembly), it is recommended that triple or double layer pouches or Al-foil
and polyethylene bag be used. These offer a convenient single-use storage
solution that maintain cleanliness levels.
In all cases it is crucial that any packaging material in direct vicinity of the
hardware has no influence on the cleanliness state of the hardware it encloses,
e.g. molecular migration in polymer materials can lead to contamination in
long-term.
EN16602-70-54:2019 (E)
From
TRANSPORT/STORAGE
PRE-CLEANING
Can the hardware
NO be semi-immersed or YES
immersed in liquid?
PRE-CLEANING methods
PRE-CLEANING methods
(in order of efficacy):
(in order of efficacy):
- Solvent Wiping * **
- Ultrasonic (solvent) * **
- UP Water Wiping
- Ultrasonic (UP water)
- Dry Wiping
- Solvent Washing/Rinsing * **
- Blowing Off
- UP Water Washing/Rinsing
- Suction
* may not be appropriate for some
* may not be appropriate for some
sensitive materials
-
sensitive materials
** organic residue left after pre-cleaning
** organic residue left after pre-cleaning
MAIN-CLEANING methods
MAIN-CLEANING
(in order of efficacy):
- CO Snow
- Plasma *
* poor particulate efficacy but can use
complementary pre-clean method
POST-CLEANING
Does the PRE-CLEAN or
Yes
MAIN-CLEAN leave
organic residue?
No
Perform POST CLEANING
POST CLEANING methods
(in order of efficacy):
- Supercritical CO *
- Hot Purge N
no POST CLEANING required
- Hot Vacuum Purge
-
- Evaporating
* hardware needs modification to
withstand applied pressure
PACKING
Will the flight hardware
Yes
be stored locally for a
short time?
NO
PACKING method:
- qualified packaging material
Does the flight hardware PACKING method:
Yes
have any offgassing
- Ultrapure N purged box
materials?
NO
PACKING method:
(in order of preference):
- FOUP/FOSB
- Sealed Box with Ar
To
TRANSPORT/STORAGE
Figure 4-6: Logic flow for the selection and optimisation of an end-to-end cleaning
process for hardware
EN16602-70-54:2019 (E)
Requirements
5.1 Specifying process
5.1.1 General
a. The customer shall provide a request for ultracleaning in conformance
with the DRD in Annex A.
b. The supplier shall provide an ultracleaning work proposal to the
customer for review and approval in conformance with the DRD in
Annex B.
c. The supplier shall provide an ultracleaning report to the customer for
review and approval in conformance with the DRD in Annex C.
d. NCRs generated during ultracleaning process applications shall be in
conformance with requirements from clause 5 to clause 6 of ECSS-Q-ST-
10-09.
e. Unless specified by the customer, cleanliness and contamination control
shall be applied for space hardware in conformance with requirements
fr
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