IEC 62496-2-5:2022

IEC 62496-2-5 ®
Edition 1.0 2022-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical circuit boards – Basic test and measurement procedures –
Part 2-5: Flexibility test for flexible opto-electric circuits

Cartes a circuits optiques – Procédures fondamentales d’essais et de mesures –
Partie 2-5: Essai de flexibilité pour les circuits optoélectriques souples

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IEC 62496-2-5 ®
Edition 1.0 2022-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Optical circuit boards – Basic test and measurement procedures –

Part 2-5: Flexibility test for flexible opto-electric circuits

Cartes a circuits optiques – Procédures fondamentales d’essais et de mesures

–
Partie 2-5: Essai de flexibilité pour les circuits optoélectriques souples

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-6119-4

– 2 – IEC 62496-2-5:2022 © IEC 2022
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Apparatus . 7
4.1 General description . 7
4.2 Flexibility tester for flexibility test of FOECBs . 8
4.2.1 FOECBs test sample of fibre optical types . 8
4.2.2 FOECBs test sample of planer waveguide optical circuit types . 8
4.3 O-E signal control source . 9
4.4 Laser source . 9
4.5 Photo detector . 9
4.6 Folding jig . 9
4.7 Relay switch . 10
4.8 Main controller . 10
5 Test sample . 10
5.1 FOECB test samples of optical fibre-types . 10
5.2 FOECB test samples of planar optical waveguide-types . 11
6 Procedures . 13
6.1 For test samples of optical fibre-types . 13
6.1.1 Preparing test samples . 13
6.1.2 Initial optical and electrical performance measurement . 13
6.1.3 Setting the test sample . 13
6.1.4 Flexibility measurement . 14
6.1.5 Final optical and electrical performance measurement . 14
6.1.6 Mechanical performance measurement . 14
6.2 For test samples of the planar optical waveguide-types. 14
6.2.1 Preparing test samples . 14
6.2.2 Initial optical and electrical performance measurement . 14
6.2.3 Setting the test sample . 15
6.2.4 Flexibility measurement . 15
6.2.5 Final optical and electrical performance measurement . 15
6.2.6 Mechanical characteristic measurement . 16
7 Report . 16
Annex A (informative) Detail requirement for structure of FOECB test samples of
optical fibre-types . 17
Annex B (informative) Requirement for structure of FOECB test samples of planar
optical waveguide-types . 18
Annex C (informative) Guideline for flexibility folding jig setting conditions of FOECB
test samples . 19
Bibliography . 20

Figure 1 – Schematic diagram of flexible opto-electric circuit board (top view) . 7
Figure 2 – Overview of the folding jig . 8
Figure 3 – Schematic diagram of the flexibility test system for fibre optical circuits . 8

Figure 4 – Schematic diagram of the flexibility test system for planar waveguide optical
circuits . 9
Figure 5 – Flexibility folding jigs (from the left, folding radius r is 1,0 mm, 2,0 mm, 3,0

mm, 4,0 mm, 5,0 mm and 10,0 mm) . 10
Figure 6 – Schematic diagram of FOECB test samples of optical fibre-types . 11
Figure 7 – Schematic diagram of FOECB test samples of planar optical waveguide-
types. 12
Figure B.1 – Schematic diagram of the flexibility test system for planar waveguide
optical circuits . 18
Figure C.1 – An example of measurement result of optical loss versus bending
diameter . 19

– 4 – IEC 62496-2-5:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL CIRCUIT BOARDS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 2-5: Flexibility test for flexible opto-electric circuits

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,
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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consensus of opinion on the relevant subjects since each technical committee has representation from all
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 62496-2-5 has been prepared by IEC technical committee 86: Fibre optics. It is an
International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
86/605/FDIS 86/609/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.

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/standardsdev/publications.
A list of all parts in the IEC 62496 series, published under the general title Optical circuit boards,
can be found on the IEC website.
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,
• replaced by a revised edition, or
• amended.
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 62496-2-5:2022 © IEC 2022
OPTICAL CIRCUIT BOARDS –
BASIC TEST AND MEASUREMENT PROCEDURES –

Part 2-5: Flexibility test for flexible opto-electric circuits

1 Scope
This part of IEC 62496 defines a test method for folding flexibility inspection of flexible opto-
electric circuits with a flexibility tester endurance tester and presents a guideline for a step
stress test method for finding the predetermined minimum mechanical folding radii below which
the flexible opto-electric circuits can be damaged by intended folding distortion. Here, test
samples are used instead of products for the flexibility test of their flexible opto-electric circuits,
and the test samples have the same material, layer structure, processing technology and
equipment as the products.
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.
IEC 60068-1, Environmental testing – Part 1: General and guidance
IEC 60793-2 (all parts), Optical fibres – Part 2: Product specifications
IEC 62496-2-1, Optical circuit boards – Part 2-1: Measurements – Optical attenuation and
isolation
ISO 5626:1993, Paper – Determination of folding endurance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62496-1 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
flexible opto-electric circuit board
flexible circuit board that contains both optic and electric circuits integrated into a flexible sheet

Figure 1 – Schematic diagram of flexible opto-electric circuit board (top view)
Note 1 to entry: Figure 1 shows an example of the top view of a flexible opto-electric circuit board.
Note 2 to entry: There are two types of flexible opto-electric circuit board: optical fibre-types and planer optical
waveguide-types.
[SOURCE: ISO 5626:1993, Clause 1]
3.2
flexibility tester
instrument for folding endurance test of flexible sheets with interchangeable folding heads,
allowing a range of thickness up to 1,25 mm
Note 1 to entry: In general, it is called the MIT folding endurance tester.
4 Apparatus
4.1 General description
The flexibility test system for flexibility test of the flexible opto-electric circuit board (hereafter
FOECB) shall be used for finding of the minimum folding radii of both optic and electric circuits
of the FOECB before any functional damage occurs. An existing flexibility folding method has
been used for testing the folding flexibility of only electric circuits. However, in this document,
it shall be used for testing the folding flexibility of both optic and electric circuits.
Since the test sample for fibre optical type should be connected to the flexibility test system
through an optical fibre, real-time monitoring may be possible. Accordingly, the flexibility tester
shall be configured with a real-time monitoring system using a laser signal device to accurately
know the time of breakage of the optical fibres.
Generally, test samples for planar waveguide optical circuits are difficult to measure through
real-time monitoring because it is not easy to connect to a flexibility test device through an
optical fibre. Therefore, the test sample should be tested by connecting only electric circuits as
in the existing flexibility folding method. The failure time of the test sample should be measured
separately using a visual light on the planar waveguide circuits.
But, in case of that the test sample for planar waveguide optical circuits shall use optical fibres
with connector to coupling with the optical waveguide, flexibility test of the test samples can be
possible with real-time monitoring.
In addition, these tests should be measured in the process of replacing the holding jig.The test
sample shall be clamped by the folding jig within the main controller as shown in Figure 2.

– 8 – IEC 62496-2-5:2022 © IEC 2022

a) Photograph diagram of the folding jig b) Photograph of a folding jig and test sample

Figure 2 – Overview of the folding jig
4.2 Flexibility tester for flexibility test of FOECBs
4.2.1 FOECBs test sample of fibre optical types
The flexibility test system for fibre optical circuits should be configured to stop the folding action
of the test sample if any damage starts to appear in its optical and electrical sections. Therefore,
the flexibility test system shall be composed of an optic-electric signal control source (hereafter
referred as O-E signal control source), test sample, and main controller, as shown in Figure 3.

Figure 3 – Schematic diagram of the flexibility test system for fibre optical circuits
4.2.2 FOECBs test sample of planer waveguide optical circuit types
The flexibility test system for planer waveguide optical circuits shall be constructed in the same
form as the folding flexibility test method for existing electrical circuits, as shown in Figure 4.

Figure 4 – Schematic diagram of the flexibility test system
for planar waveguide optical circuits
4.3 O-E signal control source
An O-E signal control source shall be composed of a laser source, photo detector, relay switch,
electric power source, optical fibre, and optical connectors. The O-E signal control source
supplies an optical signal to the test sample, and allows the photo detector to control the relay
switch based on detected optical signal for on-off switching of the electric signal flow (current)
within the flexibility test system.
4.4 Laser source
The optical output power of the laser source shall have enough larger of the minimum detected
power of optical detector and attenuation (optical loss) of samples. The laser source in the O-
E signal control source sends an optical signal to the test sample via its optical input terminal
connected to the protruded optical fibre. The wavelength and mode of the laser source should
be chosen according to the application to be used. The launching mode of the laser source
should be appropriate to the application of the relevant specification of O-E circuit board.
4.5 Photo detector
The minimum detected optical power of the photo detector shall be enough to detect the optical
power after attenuating the optical power by the test sample and light source power. The photo
detector detects the optic signal flow in the test sample. The photo detector output controls the
relay switch inside the O-E signal control source. Therefore, the output current of the photo
detector should be above the minimum operating voltage of the relay switch with a proper
resistance for the current output. The photo detector shall have enough response frequency to
detect the optical power change (deviation) by the attenuation change caused by the folding
distortion. At minimum, the response frequency for the photo detector should be 10 times or
more than the folding duration (0° to 90°), or kHz order will be necessary.
4.6 Folding jig
The size of the jig shall be selected according to the test samples. Several types of folding jigs
with different bending radii are required to apply various bending tests to the test sample.
Folding jigs of 6 different curvature radii (1,0 mm, 2,0 mm, 3,0 mm, 4,0 mm, 5,0 mm, and
10,0 mm) should be prepared (see Figure 5).

– 10 – IEC 62496-2-5:2022 © IEC 2022

Figure 5 – Flexibility folding jigs (from the left, folding radius r is
1,0 mm, 2,0 mm, 3,0 mm, 4,0 mm, 5,0 mm and 10,0 mm)
4.7 Relay switch
The switching time shall be at least one tenth of the folding speed. The relay switch plays a role
of direct on-off switching control of the electric circuit in the flexibility test system. That is, once
the photo detector detects the optic signal flow in the test sample, the relay switch stays in the
on-state. If the photo detector fails to detect the optic signal flow in the test sample, the relay
switch turns to the off-state. The relay switch operates the flexibility test system depending on
the detected optical signal output at the photo detector, which is subject to the physical state
of the test sample (e.g., either broken or non-broken state of the optic circuit).
4.8 Main controller
The main controller shall control the electrical current to fold the folding jig with enough
accuracy to test. The main controller supplies an electric current to the test sample and
mechanically controls the folding action of the test sample. The main controller may consist of
the main controller and the mechanical control means of folding, separately. Generally, the
main controller emits the electric signal by itself to perform the mechanical folding operation on
the test sample. The typical electric current flowing through the main controller ranges from
1 mA to 10 mA.
5 Test sample
5.1 FOECB test samples of optical fibre-types
Test samples of optical fibre-types shall have a pigtailed shape (see Figure 6). The optical
fibres used in the test samples may be single-mode and/or multimode fibres. Depending on
applications, glass optical fibres, polymer optical fibres, and specialty optical fibres may be
used to form the optical circuits.
The optical circuits shall be positioned at a central part of the entire FOECB test samples. The
electrical circuits shall be positioned at peripheral areas of the optical circuit in a symmetrical
structure. The symmetrical structure shall have superior characteristics in size stability from the
viewpoint of design and reliability for the FOECB test samples, as shown in Figure 6.
The test samples of the optical fibre-types shall have a protruded structure with a length of l9
at one side. The protruded length (l ) shall be maintained with sufficient length over 100 mm
for easy connection with other fibres (e.g., fibre fusion splicing). The other side of the test
samples shall have a continuous fibre bending area over a 6-mm diameter with a non-end state
as shown in Figure 6. The bending state over the 6-mm diameter for glass optical fibres shall
be maintained to minimize their optical bending loss.
A detail requirement for structure of FOECB test samples of optical fibre-types is described in
Annex A.
A position mark shall be assigned on the test sample for locating the folding position with a
clamp of the flexibility test system.

The size of the test samples should be confirmed in accordance with the flexibility folding jigs
(see 4.6). As illustrated in Figure 6, the nominal dimensions of the total length (l ) of the test
sample shall be 130 mm within 10 % tolerance, and the nominal dimensions of the width (l ) of
the test sample shall be 2,5 mm to 50 mm within 10 % tolerance. It is recommended that the
length (l ) of the test samples from its one edge to the clamp position mark and the length (l )
2 3
from the clamp position mark of the bending area to the other edge are chosen to be 100 mm
and 30 mm, respectively. The bending diameter (l ) of the optical circuit, spacing (l ) between
4 8
two optical circuit lines, and the number of optical circuits shall be decided in accordance with
the user’s requirements. The pattern width (l ) of the electrical circuit lines also shall be decided
in accordance with the user’s requirements. The thickness (l ) of the FOECB test samples is
very critical because it influences the minimum mechanical folding radius r. The thickness of
the test sample shall be from 150 µm to 500 μm for the FOECB test samples of the general
glass fibres defined in IEC 60793-2 series with polymer over-clad protection. The thickness of
the test samples should be same as that for products. If there are any differences, the thickness
of the test samples shall be decided in accordance with the user’s requirements.

Key
1 electric circuit
2 optic circuit
3 position mark for clamp (folding)
a side view of test sample
b top view of test sample
Figure 6 – Schematic diagram of FOECB test samples of optical fibre-types
5.2 FOECB test samples of planar optical waveguide-types
The optical circuits shall be positioned at a central part of the entire FOECB test samples. The
electrical circuits shall be positioned at a peripheral area of the optical circuit in a symmetrical
structure. The symmetrical structure shall have superior characteristics in size stability from the
viewpoint of design and reliability for the FOECB test samples as shown in Figure 7.
The test samples of the planar optical waveguide-types shall have a non-protruded structure at
both side (see Figure 7). The number of optical circuit lines shall be at least three for crosstalk
testing.
– 12 – IEC 62496-2-5:2022 © IEC 2022
A requirement for structure of FOECB test samples of planar optical waveguide-types is
described in Annex B.
A position mark shall be assigned on the test sample for locating the folding position with a
clamp of the flexibility test system.
The size of the test samples should be confirmed in accordance with the flexibility folding jigs
) of the test
(see 4.6). As illustrated in Figure 7, the nominal dimensions of the total length (l
sample shall be 130 mm within 10 % tolerance, and the nominal dimensions of the width (l ) of
the test sample shall be 2,5 mm to 50 mm within 10 % tolerance. It is recommended that the
length (l ) of test samples from its one edge to the clamp position mark are chosen to be 100
mm. The optical circuits shall be composed of over three optical waveguides. The spacing (l )
between two optical waveguides shall be decided in accordance with the user’s requirements.
The pattern width (l ) of the electrical circuit lines also shall be decided in accordance with the
user’s requirements. The thickness (l ) of the FOECB test sample is very critical because it
influences the minimum mechanical folding radius r. The thickness of test samples shall be
from 50 µm to 1 000 µm for FOECB test samples of the planar optical waveguide-types. The
thickness of the test samples should be same as that for products. If there are any differences,
the thickness of the test samples shall be decided in accordance with the user’s requirements.

Key
1 electric circuit
2 optic circuit
3 position mark for clamp (folding)
a side view of test sample
b top view of test sample
X1, X2, X3: input port of optical circuit
X1’, X2’, X3’: output port of optical circuit
Figure 7 – Schematic diagram of FOECB test samples
of planar optical waveguide-types

6 Procedures
6.1 For test samples of optical fibre-types
6.1.1 Preparing test samples
Prepare a number of the test samples having the same physical conditions in the same
fabrication processes.
The number of test samples should be at least 18 including 3 test samples per jig for 6 different
test jigs with folding radii of 1,0 mm, 2,0 mm, 3,0 mm, 4,0 mm, 5,0 mm and 10,0 mm.
The test sample should be 2,5 mm to 50 mm wide with a sufficient length (over 100 mm length)
to be suitable for the test instrument being used. Edges of test samples should be clean-cut to
align parallel to the edge on the opposite end.
The test sample should be initially free from any folds, wrinkles or blemishes. The portion of the
test sample where the folding action takes place should not contain any watermark traces.
Take care not to handle with bare hands any part of the test piece that is exposed between the
clamps.
6.1.2 Initial optical and electrical performance measurement
Before applying the flexibility folding test, the optical attenuation and electrical performances
of the test samples shall be measured both for no-bended and bended conditions. Optical
performance shall be measured according to IEC 62496-2-1. Electrical performance shall be
measured by LCR meter.
6.1.3 Setting the test sample
Since the test sample of the optical fibre-types has a protruded structure, both the optical fibre
and electric cable shall be connected to the test sample (see Figure 3).
The procedure for connecting the test sample to the flexibility test system is as follows:
a) Connect the optic fibres to the protruded fibres of the test sample
b) Make the optic fibre and electric wire connections between the test sample and an O-E
signal control source
c) Mount the test sample to a folding jig in flexibility test system
The flexibility folding conditions for the test samples shall be as follows:
– A set of 100, 500, 1 000, 5 000 and 10 000 folding cycles is used as the basis point for
finding an appearance of breakage and/or crack of the test samples
– Folding radius r: 1,0 mm to 10,0 mm
– Pulling force: 5 N to 15 N
– Folding speed: 30 cycles/min to 175 cycles/min
– Folding angle: 135° ± 5°
A general guideline for the flexibility folding jig setting conditions of the FOECB test samples is
described in Annex C.
Record the pulling force, thickness and the width (cross-section) of the test sample and the
bending angle. If required, the temperature chamber of controllable from −40 °C to +100 °C
should be prepared. The test ambient temperature should be decided between users and
manufacturers.
– 14 – IEC 62496-2-5:2022 © IEC 2022
6.1.4 Flexibility measurement
Appearance of any breakage and/or crack of the test sample during the folding test process
should be monitored through the monitor panel of the flexibility tester main controller. The
folding test shall be repeated with the flexibility folding jigs of a series of different radii (see
Figure 3) by replacing one by one. The flexibility folding test should be started with the jig of a
large folding radius r value (10,0 mm) at the beginning, and repeated by replacing it with
another jig of gradually reduced folding radius r until any breakage and/or crack of the test
sample starts to appear during the folding process. Once any damage appears during the
folding process, then the folding radius r of the jig shall be regarded as a critical point value for
the folding limit of the test sample.
Any damage and delamination during the folding test cannot be observed during real-time
monitoring, so appeared damage cannot be used as a termination criteria. Therefore, the
damage and delamination appearance test during the folding test process also shall be
regarded as the termination criteria.
6.1.5 Final optical and electrical performance measurement
After the final folding test, the test sample should be kept in the standard atmospheric condition
defined in IEC 60068-1 during more than or equal to 2 hours. Then, measure the optical
attenuation and electrical performance of the test sample in the same conditions as ones used
for the same measurement before the folding test. Calculate the deviation of the measured
optical attenuation and electrical resistance values between before and after the folding test.
6.1.6 Mechanical performance measurement
After the final optical and electrical characteristic measurement, inspect the test samples for
any peeling and buckling of the circuit layer. If required, optical fibres dimensions, optical fibres
pitch (relative core locations), the peeling strength should be measured.
6.2 For test samples of the planar optical waveguide-types
6.2.1 Preparing test samples
Prepare a number of the test samples having the same physical conditions in the same
fabrication processes.
The number of the test samples should be at least 18, including 3 test samples per jig for 6
different test jigs with folding radii of 1,0 mm, 2,0 mm, 3,0 mm, 4,0 mm, 5,0 mm and 10,0 mm.
The test sample should be 2,5 mm to 50 mm wide with a sufficient length (over 100 mm length)
to be suitable for the test instrument being used. Edges of the test samples should be clean-
cut to align parallel to the edge on the opposite end.
The test sample should be initially free from any folds, wrinkles or blemishes. The portion of the
test sample where the folding action takes place should not contain any watermark traces.
Take care not to handle with bare hands any part of the test piece that is exposed between the
clamps.
6.2.2 Initial optical and electrical performance measurement
Before applying the flexibility folding test, the optical performance (attenuation and crosstalk)
and electric performance of the test samples shall be measured both for no-bended and bended
conditions.
Optic performance should be measured according to IEC 62496-2-1. Electrical performance
shall be measured by LCR meter.

6.2.3 Setting the test sample
Since the test sample of the planar waveguide-types has a non-protruded structure, only the
electric cable should be connected to the test sample (see Figure B.1).
The procedure for connecting the test sample to the flexibility test system is as follows:
a) Mount the test sample to a folding jig in flexibility test system
b) Make the electric wire connections between the test sample and a main controller
Take care of the test sample not to cause any damage during the mounting process.
The flexibility folding conditions for the test sample are as follows:
– A set of 100, 500, 5 000, and 10 000 folding cycles is used as the basis point for finding an
appearance of breakage and/or crack of the test sample
– Folding radius r: 1,0 mm to 10,0 mm
– Pulling force: 5 N to 15 N
– Folding speed: 90 cycles/min to 175 cycles/min
– Folding angle: 135° ± 5°
Record the pulling force, thickness and the width (cross-section) of the test sample and the
bending angle. If required, the temperature chamber of controllable from −40 °C to +100 °C
should be prepared. The test ambient temperature should be decided between users and
manufacturers.
6.2.4 Flexibility measurement
Appearance of any breakage and/or crack of electric circuits inside the test sample during the
folding test process should be monitored through the monitor panel of the flexibility tester main
controller. The folding test shall be repeated with the flexibility folding jigs of a series of different
radii (see Figure 3) by replacing one by one. The flexibility folding test should be started with
the jig of a large folding radius r value (10,0 mm) at the beginning, and repeated by replacing
it with another jig of gradually reduced folding radius r until any breakage and/or crack of the
test sample starts to appear during the folding process. Once any damage appears during the
folding process, then the folding radius r of the jig shall be regarded as a critical point value for
the folding limit of the test sample.
After the end of the flexibility folding test, whether the optical circuit in the test sample is
damaged or not, should be determined through evaluation of separate optical performance.
Any damage and delamination during the folding test cannot be observed during real-time
monitoring, so appeared damage cannot be used as a termination criteria. Therefore, the
damage and delamination appearance test during the folding test process also shall be
regarded as the termination criteria.
6.2.5 Final optical and electrical performance measurement
After the folding test, the test sample should be kept in the standard atmospheric condition
(defined in IEC 60068-1) more than or equal to 2 hours. Measure the optical performance
(attenuation and crosstalk) and electrical performance same as the measurement condition
before the folding test. Calculate the deviation of optical performance (attenuation and
crosstalk)/electrical resistance values between before and after the folding test.

– 16 – IEC 62496-2-5:2022 © IEC 2022
6.2.6 Mechanical characteristic measurement
After the final optical and electrical characteristic test, inspect the test samples for any peeling
and buckling of the circuit layers. If required in the relevant document, optical core dimensions,
optical core pitch (relative core locations), and peeling strength should be measured.
7 Report
In cases where the specification of the present flexibility measurement shall be included in the
report, the following shall be explained in detail:
a) model number of the test sample
b) manufacturer information of the rest sample
c) material type of the test sample
d) layer structure of the test sample
e) test sample size: W (Width) × L (Length) × T (Thickness) (mm)
f) test sample type: optical fibre-types (single-mode or multimode) or planar optical
waveguide-types (single-mode or multimode)
g) type of light source, its launching condition
h) type of optical detector and its response frequency
i) ambient temperature and humidity conditions
j) flexibility folding test conditions (folding radius, pulling force, folding cycle, folding angle)
k) optical performance (attenuation and crosstalk) and electric performance (resistance
values) before and after folding test
l) average limit of flexibility (folding cycle number at folding radius) should be reported at least
with three specimens
Annex A
(informative)
Detail requirement for structure of FOECB
test samples of optical fibre-types
Test samples of optical fibre-types can be broken suddenly during the flexibility folding test. In
particular, optical circuits composed of glass fibres are relatively rigid compared to those with
polymer fibres, and can be easily broken in repeated folding processes. Accordingly, optical
attenuation values and electrical resistance values of test samples of optical fibre-types should
be monitored in real-time to confirm the presence of breakage during the flexibility folding test.
Accordingly, one side of test samples of optical fibre-types should be formed with a protruding
optical fibre, and the opposite side thereof should be formed with a non-protruding structure.
When the test sample is m
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