Space systems — Adhesives — General requirements

This document specifies general requirements for adhesive selection with the adhesive bonding process and quality assurance used in space systems. This document can be applied to different types of adhesive materials in space systems, such as launch vehicles, satellites, spacecraft and space station for the following applications: bonding, components embedding (only for space application), sealing, fixing and repairing.

Systèmes spatiaux — Adhésifs — Exigences générales

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Status
Published
Publication Date
15-Nov-2022
Current Stage
6060 - International Standard published
Due Date
02-Oct-2022
Completion Date
16-Nov-2022
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INTERNATIONAL ISO
STANDARD 24564
First edition
2022-11
Space systems — Adhesives — General
requirements
Systèmes spatiaux — Adhésifs — Exigences générales
Reference number
ISO 24564:2022(E)
© ISO 2022
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ISO 24564:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
© ISO 2022 – All rights reserved
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ISO 24564:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Selection requirements for adhesive materials ................................................................................................................. 3

4.1 General requirements ...................................................................................................................................................................... 3

4.1.1 Classification of adhesive application ............................................................................................................. 3

4.1.2 Selection criterion ............................................................................................................................................................. 4

4.2 Selection procedure ........................................................................................................................................................................... 4

4.2.1 Primary characteristics before selection ..................................................................................................... 4

4.2.2 Selection steps ...................................................................................................................................................................... 7

5 Test methods for adhesive properties .......................................................................................................................................... 8

5.1 General ........................................................................................................................................................................................................... 8

5.2 Shrinkage .................................................................................................................................................................................................... 8

5.3 Adhesion ....................................................................................................................................................................................................... 8

5.4 Glass transition temperature .................................................................................................................................................... 9

5.5 Electrical volume resistivity ...................................................................................................................................................... 9

5.6 Thermal decomposition temperature ............................................................................................................................... 9

5.7 Thermal conductivity ....................................................................................................................................................................... 9

5.8 Thermal expansion ............................................................................................................................................................................. 9

5.9 Ground environment durability .............................................................................................................................................. 9

5.10 Outgassing .................................................................................................................................................................................................. 9

5.11 UV-resistance ........................................................................................................................................................................................... 9

5.12 Radiation resistance ....................................................................................................................................................................... 10

5.13 Atomic oxygen resistance .......................................................................................................................................................... 10

6 Lifetime verification and failure ........................................................................................................................................... ...........10

6.1 Lifetime verification ....................................................................................................................................................................... 10

6.2 Failure.......................................................................................................................................................................................................... 10

6.2.1 Failure mode........................................................................................................................................................................ 10

6.2.2 General failure analysis and preventive measures .......................................................................... 10

7 Adhesive bonding process design, safety and environmental protection

requirements ........................................................................................................................................................................................................11

7.1 General requirements ................................................................................................................................................................... 11

7.2 Process technology and tool design requirements ............................................................................................. 11

7.3 Safety and environmental protection requirements ........................................................................................12

8 Quality assurance requirements .....................................................................................................................................................12

8.1 General requirements ...................................................................................................................................................................12

8.2 Inspection ................................................................................................................................................................................................12

8.3 Traceability ............................................................................................................................................................................................. 13

8.4 Worker and inspector training .............................................................................................................................................13

Annex A (informative) Reference tables .......................................................................................................................................................15

Bibliography .............................................................................................................................................................................................................................18

iii
© ISO 2022 – All rights reserved
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ISO 24564:2022(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 20, Aircraft and space vehicles,

Subcommittee SC 14, Space systems and operations.

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.
© ISO 2022 – All rights reserved
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ISO 24564:2022(E)
Introduction

The organic adhesive materials have been widely applied in most components of space systems, not

only for structural adhesion but also in embedding electronic units and fixing little devices. Hence, the

reliability and performance of adhesive materials is essential to the space system performance and

safety. Especially for space applications, the environmental adaptability and reliability of adhesive

materials is the critical factor to mission schedule and success. This document establishes primary

characteristics requirements, selection criterion and procedure for helping space system designer or

manufacturer select the best-fit adhesive. Manufacturing process requirements and quality assurance

for adhesive materials selection are provided to confirm their compliance with the requirements of

space applications. Annex A provides references for general test methods for property characterization,

additional surface preparation and cleaning requirements, and verification of the adhesive lifetime.

© ISO 2022 – All rights reserved
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INTERNATIONAL STANDARD ISO 24564:2022(E)
Space systems — Adhesives — General requirements
1 Scope

This document specifies general requirements for adhesive selection with the adhesive bonding process

and quality assurance used in space systems.

This document can be applied to different types of adhesive materials in space systems, such as launch

vehicles, satellites, spacecraft and space station for the following applications: bonding, components

embedding (only for space application), sealing, fixing and repairing.
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 14624-3, Space systems — Safety and compatibility of materials — Part 3: Determination of offgassed

products from materials and assembled articles
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology 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
coefficient of linear thermal expansion

reversible increase of a material per unit length per degree change in temperature

3.2
coefficient of moisture expansion
CME
Δll/
α =
CME
mm/
watersample
where
∆l/l is the relative length change referred to as strain;
m is the weight of the absorbed water;
water
m is the dry weight of the sample
sample
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ISO 24564:2022(E)
3.3
curing

process of converting a prepolymeric or polymeric composition into a more stable, usable condition by

polymerization and/or crosslinking

Note 1 to entry: With adhesives, curing results in the development of the strength properties.

[SOURCE: ISO 472:2013, 2.243, modified — The alternative preferred term "cure, noun" has been

removed; the original note 1 to entry has been removed; the original note 2 to entry has become note 1

to entry.]
3.4
glass transition temperature

approximate midpoint of the temperature range over which the glass transition takes place

Note 1 to entry: The glass transition temperature varies significantly, depending upon the specific property and

the test method and conditions selected to measure it.
[SOURCE: ISO 472:2013, 2.441, modified — The symbol T has been added.]
3.5
liner

treated sheet to cover the adhesive temporarily to facilitate handling or unrolling

[SOURCE: ISO 29862:2018, 3.6]
3.6
pot life

maximum period of time during which a multi-part adhesive can be used after mixing the components

[SOURCE: ISO 10364:2015, 3.1, modified — The alternative preferred term "working life" has been

removed.]
3.7
substrate

object or semi-manufactured product (e.g. wire, extruded metallic section or plastic profile, sheet, film,

paper, textile product) on which a coating or layer of another material is applied from the gas, liquid or

solid phase by coating, by laminating or generated by a chemical process

Note 1 to entry: In adhesion, the term “substrate” often is a synonym of adherend.

[SOURCE: ISO 472:2013, 2.1128, modified — Note 2 to entry has been removed.]
3.8
surface preparation

physical and/or chemical treatments applied to adherends to render them suitable (or more suitable)

for bonding

[SOURCE: ISO 472:2013, 2.1613, modified — The alternative preferred term "surface pretreatment" has

been removed.]
3.9
thermal conductivity

proportionality coefficient that represents the relationship of heat flux and temperature gradient,

where heat flux on an isothermal surface is proportional to the temperature gradient in the normal

direction on the isothermal surface
Note 1 to entry: It is expressed in watt per meter kelvin (W/m*k).
[SOURCE: ISO 16525-3:2014, 3.6, modified — The symbol k has been removed.]
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ISO 24564:2022(E)
3.10
thermal decomposition

process whereby the action of heat or elevated temperature on an item causes changes in the chemical

composition
[SOURCE: ISO 472:2013, 2.1285, modified — Note 1 to entry has been removed.]
3.11
volume resistivity

electrical resistance of the isotropic electrically conductive adhesive for a given cross-sectional area or

given length

Note 1 to entry: Electrical volume resistivity is converted to resistance per given cross-sectional area or given

length of the isotropic electrically conductive adhesive. ISO 16525-2 specifies measurement methods for an

isotropic electrically conductive adhesive, which is applied to a circuit board that is similar to the one used in

practice.
Note 2 to entry: It is expressed as ohm metre (Ω·m).
[SOURCE: ISO 16525-2:2014, 3.2, modified — The symbol ρ has been removed.]
4 Selection requirements for adhesive materials
4.1 General requirements
4.1.1 Classification of adhesive application

The application of adhesives used in space systems includes fixing, bonding, sealing, embedding and

repairing, as shown in Figure 1.
a) Fixing: using the adhesive to reinforce the joints of connected components.

b) Bonding: state in which two materials surfaces are held together by interfacial forces formed by

the adhesive.

c) Sealing: application of the adhesive to the seam of two components, in order to keep the vacuum or

decrease the inner gas releasing.

d) Embedding: process of encasing completely a component by pouring the adhesive over it and

curing.
e) Repairing: the damage part is repaired by the adhesive.
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ISO 24564:2022(E)
Figure 1 — Application of adhesive used in space systems
4.1.2 Selection criterion

a) The workability of adhesive materials is highly dependent on the environmental conditions under

which the spacecraft is operated. The designer shall fully consider the application environment of

the space mission. Adhesive materials shall cope with the performances required during the life

on-ground and during its service life.

b) For a new mission or product, materials already qualified for other missions or products should

be evaluated before the final selection. This evaluation should be based on the environmental

conditions of the new mission and design requirements of the new product, the joint design, and

performance requirements of the new product. If there is no available adhesive that can meet the

mission requirement, the designer can start the selection of a new adhesive.

c) For a new adhesive and process, a series of experimental qualification shall be done according to

the mission requirements.

d) Verification reports and procedures shall be approved by the designer, project manager and quality

manager. When requested by the customer and agreed by contract, verification documents shall be

also approved by the customer.

e) The designer shall choose an adhesive supplier that can provide the manufacturing process data

for traceability.
4.2 Selection procedure
4.2.1 Primary characteristics before selection

The selection of the adhesive is based on the knowledge of key characteristics depending on the

application as described in Figure 1. These characteristics are listed in Table 1.

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ISO 24564:2022(E)
Table 1 — Primary characteristics considered for adhesive selection
Application classification
Properties Remarks on selection
Bonding Sealing Embedding Fixing Repairing
The shrinkage determines the vol-
ume change in curing process; it also
Shrinkage + + + + +
determines the internal stress and
apparent planeness.
The adhesion requirement differs be-
tween structural bonding and sealing.
The strength of structural bonding
strongly depends on the type of the
Adhesion + + + + +
adhesive, the type of the substrate
and the type of design of the joint; the
test method should be chosen based
on the system structure.
For organic adhesives, the glass tran-
sition temperature should be outside
of the operating temperature range
for the adhesive to ensure the stability
of the adhesive's properties. But with
Glass transition regard to cold-setting adhesives, the
+ + - - +
temperature glass-melting temperature cannot be
beyond operating temperature limits.
For T characterization, the designer
shall remove the moisture factor. T
characterization shall be determined
in wet condition for launchers.
When the adhesive is used for electric
conduction or electrically insulating
adhesion (adhesives used in wiring, die
Electrical vol- attach of semiconductor, and surface
+ + + - -
ume resistivity assembly of printed circuit boards),
electrical resistivity should have low
sensitivity to temperature in the work-
ing temperature range.
When a thermal conductive adhesive
Thermal con- is used for embedding and bonding,
+ + + - -
ductivity thermal conductivity should meet the
design requirement.
Thermal decomposition temperature
limits the highest operating tem-
Thermal de-
perature of the adhesive; it also can
composition + + + - +
be used to judge the change of the
temperature
adhesive's molecule structure after
the environment adaptability test.
Outgassing characters of the adhe-
sive shall fulfil the contamination
requirement of the space systems.
Outgassing + + + + +
The quantity of outgas is different
depending on the adhesive molecule
and the moisture structure.
The minimum and maximum temper-
ature values, at which properties of
Operating tem-
+ + + + + bonding, sealing embedding, fixing
perature
and repairing variate according to
the designer requirement.
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ISO 24564:2022(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Application classification
Properties Remarks on selection
Bonding Sealing Embedding Fixing Repairing
Adhesives applied on the outer sur-
face of a spacecraft are subject to UV
rays. Thermodynamic properties and
adhesion are degraded by UV. The
UV-resistance + + - + +
amount of UV received by a spacecraft
is determined by the orbital altitude,
expected lifetime and shielding effect
of the spacecraft.
Adhesives should withstand levels
of electrons and protons radiation.
Thermodynamic properties and ad-
Electrons, pro-
hesion are degraded by radiation.
tons radiation + + + + +
The dose received by a spacecraft is
resistance
determined by the orbital altitude,
expected lifetime and shielding effect
of the spacecraft.
Adhesives applied on the outer sur-
face of a spacecraft are exposed to a
Atomic oxygen large quantity of atomic oxygen which
+ + - + +
resistance depends on the orbital altitude. Ther-
modynamic properties and adhesion
are affected by atomic oxygen.
When the adhesive is used to bond
Refractive an optical device, the thermal-optical
+ + + - -
index properties shall satisfy the mission
requirement.
The adhesive shall withstand tem-
Thermal stress perature cycling. The temperature
+ + + + +
resistance cycling test of the adhesive shall be
performed with substrates.
The adhesive shall withstand chemical
and biological corrosion. The physical
Corrosion re- and chemical properties of the adhe-
+ + + + +
sistance sive are affected by corrosion. The
corrosion test method is determined
by the environment of space systems.
Accelerated environmental tests are
Service life + + + + + used to estimate the life time of the
adhesive.
The thermal expansion determines
the volume change of the adhesive
in working temperature; also it can
Thermal expan-
+ - + - + influence the stress generated by the
sion
adhesive. The designer shall give a
definition value based on the mission
requirements.
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ISO 24564:2022(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Application classification
Properties Remarks on selection
Bonding Sealing Embedding Fixing Repairing
The hygroscopic or moisture expan-
sion determines the volume change
of adhesives due to absorption and
desorption of moisture, which can
influence the stress generated by the
adhesive. The designer shall consider
these effects in frame of the adhesive
Moisture ex- selection and joint definition based
- + - + +
pansion on the mission requirements of the
respective configuration, for example,
moisture absorption shall be consid-
ered in case of stringent requirements
on dimensional stability. The coeffi-
cient of moisture expansion should
be given if required by the mission
or the customer.
4.2.2 Selection steps

Selecting the right step is key to finding the best-fit adhesive efficiently. Figure 2 shows a flowchart for

the selection of a new adhesive.

a) The designer shall define the mission requirement before adhesive selection, including system or

component structure, environmental conditions, the application’s performance levels, etc.

b) Adhesive selection shall be made by designers based on their concern(s) on the physical and

chemical properties of the adhesive, and then the designers select the potential available adhesive

for further test.

c) The space system manufacturer shall design a reliable manufacturing process, which is achievable

and controlled. The configuration, the cleaning, the application of chemical conversion coating,

primers and the surface preparation of the part(s) to be sealed or glued are considered as critical

parameters of the adhesive bonding process, which govern the performance of the adhesion.

d) Standardized test methods shall be selected to assure adhesive application performance and

material compatible. Accelerated environmental tests like thermal cycle, thermal acceleration and

irradiation also shall be performed according to representative conditions of the mission or the

product environment.

e) After completing the first four steps, if there are several potential adhesives which meet the mission

requirements, the designer shall choose the best one after considering economic, environment, safe

and healthy regulations constraints. But if there are no adhesive to meet the mission requirements,

the designer shall go back to step a) and re-evaluate more adhesives, or change design (adhesion

structure, load pass) and service conditions (temperature, radiation dose) until finding one

available adhesive.
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ISO 24564:2022(E)
Figure 2 — The procedure of adhesive selection
5 Test methods for adhesive properties
5.1 General

The adaptability and reliability of adhesive are confirmed by testing properties. Appropriate test

methods shall be selected based on the actual application; and the test plan shall be reviewed by

the designer and the customer. The test report shall be approved and registered. Table A.1 provides

methods to perform the measurement tests for the properties specified in 5.2 to 5.13.

5.2 Shrinkage

Shrinkage characters are obtained by measuring the volume or thickness change of the adhesive before

and after curing. The curing process (temperature, moisture and intensity of illumination) affects the

shrinkage behaviour of the adhesive.
5.3 Adhesion

The adhesive strength is obtained by using appropriate standard methods on representative test sample

of the real joint system structure (same substrate surface preparation process, cleaning process, curing

process).
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ISO 24564:2022(E)
5.4 Glass transition temperature

The glass transition temperature of the adhesive can be obtained through measuring dynamic

mechanical properties and the expansion coefficient method. The curing process of test samples shall

be identical to products.
5.5 Electrical volume resistivity

The electrical volume resistivity of the adhesive is obtained using the measuring probes and an

appropriate voltage or resistance meter.

The measuring devices shall have the required accuracy and smooth regulation of the applied test

voltage. The humidity, temperature, pressure, etc. of measurement shall be recorded.

5.6 Thermal decomposition temperature

The thermal decomposition temperature of the adhesive can be determined by the method of

thermogravimetric analysis under inert gas atmosphere. The samples for thermal decomposition

temperature test shall have the same preparation process with products.
5.7 Thermal conductivity

The thermal conductivity of the adhesive can be obtained through steady-state heat flow meter

apparatus and the pulsed laser flash method. Dimensions of the samples shall be selected by reference

to the requirements of the applied test method. The samples shall have identical thickness and smooth

surfaces to decrease test err
...

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