SIST EN IEC 63251:2024

SLOVENSKI STANDARD
01-februar-2024
Metoda preskušanja mehanskih lastnosti toplotno obremenjenih zvijavih
optoelektričnih tiskanih vezij
Test Method for Mechanical Property of Flexible Opto-Electric Circuit Boards under
Thermal Stress
Prüfverfahren für mechanische Eigenschaften von elektrisch-optischen Leiterplatten
unter Wärmebeanspruchung
Méthode d’essai des propriétés mécaniques des circuits opto-électriques souples sous
contrainte thermique
Ta slovenski standard je istoveten z: EN IEC 63251:2023
ICS:
31.180 Tiskana vezja (TIV) in tiskane Printed circuits and boards
plošče
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 63251

NORME EUROPÉENNE
EUROPÄISCHE NORM December 2023
ICS 31.180
English Version
Test method for mechanical properties of flexible opto-electric
circuit boards under thermal stress
(IEC 63251:2023)
Méthode d'essai des propriétés mécaniques des circuits Prüfverfahren für mechanische Eigenschaften von
optoélectriques souples sous contrainte thermique elektrisch-optischen Leiterplatten unter
(IEC 63251:2023) Wärmebeanspruchung
(IEC 63251:2023)
This European Standard was approved by CENELEC on 2023-12-06. 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 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 63251:2023 E
European foreword
The text of document 91/1898/FDIS, future edition 1 of IEC 63251, prepared by IEC/TC 91
"Electronics assembly technology" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 63251:2023.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2024-09-06
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-12-06
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 63251:2023 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60793-2 (series) NOTE Approved as EN 60793-2 (series)
IEC 62496-3-1 NOTE Approved as EN 62496-3-1
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60068-2-2 - Environmental testing - Part 2-2: Tests - EN 60068-2-2 -
Test B: Dry heat
IEC 60068-2-14 - Environmental testing - Part 2-14: Tests - EN IEC 60068-2-14 -
Test N: Change of temperature
IEC 60068-2-78 - Environmental testing - Part 2-78: Tests - EN 60068-2-78 -
Test Cab: Damp heat, steady state

IEC 63251 ®
Edition 1.0 2023-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test method for mechanical properties of flexible opto-electric circuit boards

under thermal stress
Méthode d’essai des propriétés mécaniques des circuits optoélectriques

souples sous contrainte thermique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.180  ISBN 978-2-8322-7750-8

– 2 – IEC 63251:2023 © IEC 2023
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Test method . 7
4.1 General . 7
4.2 Test sample . 7
4.3 Test process . 8
4.3.1 General description of the test . 8
4.3.2 Preconditioning . 9
4.3.3 Test . 9
4.3.4 Recovery . 9
4.3.5 Final measurements . 10
5 Report . 10
Annex A (informative)  Example of optical bending loss test results with general glass
optic fibres . 11
Annex B (informative) Example of preparation method of O-E circuit test samples
(optic fibre type) . 12
B.1 General . 12
B.2 Manufacturing processes of the FOECBs with optic fibres (POF, GOF) . 12
B.3 Manufacturing processes of the FOECBs with optical polymer waveguides . 13
B.4 Characteristics of the optic fibres . 14
Annex C (informative) Example of reflow assembly simulation test results . 15
C.1 General . 15
C.2 Results of reflow assembly simulation test for a LED chip mounted FOECB
with GOF . 15
C.3 Results of reflow assembly simulation test for a transparent FOECB with
GOF for display applications . 16
C.4 Results of reflow assembly simulation test for a polyimide (PI) based FOECB
with GOF . 16
C.5 Results of reflow assembly simulation test for a polymer-based FOECB . 17
Annex D (informative) Example of thermal shock endurance test results . 18
D.1 General . 18
D.2 Results of thermal shock endurance test for an FOECB with GOF . 18
Annex E (informative) Example of humidity storage test results . 19
E.1 General . 19
E.2 Results of humidity storage test for an FOECB with GOF . 19
E.3 Results of humidity storage test for an FOECB with POF . 19
Bibliography . 21

Figure 1 – Schematic diagram of FOECB (top view) . 7
Figure 2 – Schematic diagrams of the FOECB test samples of fibre type . 8
Figure 3 – Schematic diagram of the FOECB test samples of fibre type . 8
Figure A.1 – Bending loss test setup . 11
Figure A.2 – Optical loss versus bending diameter . 11
Figure B.1 – Arrayed structure of the FOECB test samples formed on one sheet . 12

IEC 63251:2023 © IEC 2023 – 3 –
Figure B.2 – Fabrication of the optic circuits with optic fibres . 13
Figure B.3 – Fabrication of the optic circuits with optic polymer waveguide via the
photo-etching method . 13
Figure C.1 – LED chip mounted FOECB. 15
Figure C.2 – Appearance of a LED chip mounted FOECB after the reflow assembly

simulation test . 15
Figure C.3 – Appearance of a transparent FOECB with GOFs after the reflow assembly
simulation test . 16
Figure C.4 – Appearance of a PI based FOECB with GOF after the reflow assembly
simulation test . 16
Figure C.5 – Appearance of a polymer-based FOECB after the reflow assembly

simulation test . 17
Figure D.1 – Appearance of an FOECB with GOF after the thermal shock test . 18
Figure E.1 – Appearance of an FOECB with GOF after the humidity storage test . 19
Figure E.2 – Appearance of an FOECB with POF after the humidity storage test . 20

Table 1 – Thermal endurance test class for FOECB . 9

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHOD FOR MECHANICAL PROPERTIES OF FLEXIBLE
OPTO-ELECTRIC CIRCUIT BOARDS UNDER THERMAL STRESS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
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misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 63251 has been prepared by IEC technical committee 91: Electronics assembly technology.
It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
91/1898/FDIS 91/1914/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

IEC 63251:2023 © IEC 2023 – 5 –
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 63251:2023 © IEC 2023
TEST METHOD FOR MECHANICAL PROPERTIES OF FLEXIBLE
OPTO-ELECTRIC CIRCUIT BOARDS UNDER THERMAL STRESS

1 Scope
This International Standard defines the thermal endurance test methods for reliability
assessment of flexible opto-electric circuit boards. The purpose of this document is to
accommodate the uniform thermal characteristics required by the flexible opto-electric circuit in
high temperature environments such as automobiles. In particular, this document specifies a
test method to inspect the occurrence of colour exchange, deformation and delamination of
flexible opto-electric circuit boards under thermal stress.
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 editio
...