IEC 61249-6-3:2023

IEC 61249-6-3
®

Edition 1.0 2023-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Materials for printed boards and other interconnecting structures –
Part 6-3: Sectional specification set for reinforcement materials – Specification
for finished fabric woven from "E" glass for printed boards

Matériaux pour circuits imprimés et autres structures d’interconnexion –
Partie 6-3: Ensemble de spécifications intermédiaires pour matériaux de renfort
– Spécification des tissus finis en verre "E" pour circuits imprimés

IEC 61249-6-3:2023-06(en-fr)

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IEC 61249-6-3

®


Edition 1.0 2023-06




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Materials for printed boards and other interconnecting structures –

Part 6-3: Sectional specification set for reinforcement materials – Specification

for finished fabric woven from "E" glass for printed boards



Matériaux pour circuits imprimés et autres structures d’interconnexion –

Partie 6-3: Ensemble de spécifications intermédiaires pour matériaux de renfort


– Spécification des tissus finis en verre "E" pour circuits imprimés













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 31.180 ISBN 978-2-8322-7070-7




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 61249-6-3:2023 © IEC 2023
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Visual requirements . 9
5 Physical requirements . 10
5.1 Fabric count . 10
5.2 Weave type . 10
5.3 Fabric thickness . 10
5.4 Fabric weight . 10
5.5 Fabric length . 10
5.6 Fabric width . 10
5.7 Feather length . 10
5.8 Filament diameter . 10
5.9 Bare glass nominal measurement . 11
6 Chemical requirements . 11
7 Electrical requirements . 11
7.1 Dielectric constant . 11
7.2 Dissipation factor . 11
8 Workmanship requirements . 12
8.1 Splices . 12
8.2 Laser machinability performance . 12
8.3 Alternate fabric styles and weaves . 12
9 Quality assurance . 12
9.1 Statistical process control (SPC) . 12
9.2 Responsibility for inspection . 13
9.3 Test equipment and inspection facilities . 13
9.4 Preparation of samples . 13
9.5 Standard laboratory conditions . 13
9.6 Inspection requirements and acceptability . 13
9.6.1 General . 13
9.6.2 Sample size . 13
9.6.3 Sampling plans . 14
9.6.4 Acceptable quality level (AQL) . 14
9.7 Test methods . 14
9.7.1 Fabric appearance . 14
9.7.2 Fabric count . 15
9.7.3 Weave type . 15
9.7.4 Fabric thickness . 15
9.7.5 Weight per unit area . 15
9.7.6 Fabric length . 16
9.7.7 Fabric width . 16
9.7.8 Finish level (organic content) . 16
9.7.9 Bias or bowed filling . 17
10 Preparation for delivery . 17
10.1 Preservation and packaging . 17

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IEC 61249-6-3:2023 © IEC 2023 – 3 –
10.2 Packing . 17
10.3 Marking . 17
11 Additional Information . 17
11.1 Ordering data . 17
11.2 New styles . 17
Annex A (normative) Finished fabric glass styles in SI units . 18
Bibliography . 21

Table 1 – Classification of defects . 9
Table 2 – Filament Thdiameter designations . 10
Table 3 – Bare glass nominal measurements . 11
Table 4 – Sample size per number of rolls shipped . 13
Table 5 – Sample size per length of individual roll shipped and

the acceptable quality level . 14

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– 4 – IEC 61249-6-3:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MATERIALS FOR PRINTED BOARDS AND OTHER
INTERCONNECTING STRUCTURES –

Part 6-3: Sectional specification set for reinforcement materials –
Specification for finished fabric woven from "E" glass for printed boards

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
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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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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.
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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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 61249-6-3 has been prepared by IEC technical committee 91: Electronics assembly
technology. It is an International Standard.
This first edition cancels and replaces the IEC/PAS 61249-6-3 published in 2011. This edition
constitutes a technical revision.
The text of this International Standard is based on the following documents:
Draft Report on voting
91/1680/CDV 91/1828A/RVC

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.

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IEC 61249-6-3:2023 © 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/standardsdev/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,
• replaced by a revised edition, or
• amended.

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– 6 – IEC 61249-6-3:2023 © IEC 2023
MATERIALS FOR PRINTED BOARDS AND OTHER
INTERCONNECTING STRUCTURES –

Part 6-3: Sectional specification set for reinforcement materials –
Specification for finished fabric woven from "E" glass for printed boards



1 Scope
This part of IEC 61249 covers finished fabrics woven from ‘‘E’’ glass electrical grade glass fibre
yarns that are intended as a reinforcing material in laminated plastics for electrical and
electronic use. All fabrics covered by this specification are plain weave.
This specification determines the nomenclature, definitions, general and chemical requirements
for the glass, and physical requirements for finished woven glass fibre fabrics.
Annex A of this document provides a style designator for each finished fabric glass style, with
specifications on yarn, fabric count, thickness and weight in both SI and US system.
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.
There are no normative references in this document.
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:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
AQL
Acceptable Quality Level
maximum number of defects per hundred units that can be considered satisfactory as a process
average
3.2
bias
filling yarns are off-square to the warp ends
3.3
bow
filling yarns lie in an arc across the width of the fabric

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IEC 61249-6-3:2023 © IEC 2023 – 7 –
3.4
creases
ridge in the fabric caused by a fold or wrinkle being placed under pressure
3.5
defect
substandard area in a fabric
3.5.1
major defect
defect that is likely to result in failure, or to reduce materially the usability of the unit of product
for its intended purpose
3.5.2
minor defect
defect that is not likely to reduce materially the usability of the unit of product for its intended
purpose
3.6

E-glass
Electrical Glass which is to be used for printed board applications, is a continuous filament
glass yarn with a chemical composition by weight that is within the following limits:

B2O3 5 % to 10 %
CaO 16 % to 25 %
Al2O3 12 % to 16 %
SiO2 52 % to 56 %
MgO 0 % to 5 %
Na2O / K2O 0 % to 2 %
TiO2 0 % to 0,8 %
Fe2O3 0,05 % to 0,4 %
F2 0 % to 10 %

Note 1 to entry: For convenience, the composition of borosilicate glass is often expressed in terms of oxides (B2O3,
SiO2, Al2O3, Na2O, CaO, etc.). This does not imply anything about the nature and structure of glass. Borates are
network formers and are part of the structure of borosilicate glass. All raw materials are completely consumed during
manufacturing, and no raw materials are present in the final product.
3.7
permittivity for bulk form E glass
reference dielectric constant to be used for printed board applications
3.8
feather length
distance from last warp end to the end of the pick
3.9
fabric finish
treatment of fabric to aid in compatibility with resins
3.10
fish eye
small area of fabric which resists resin wetting and can be caused by the resin system, fabric
or treatment

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– 8 – IEC 61249-6-3:2023 © IEC 2023
3.11
hollow filament
individual filament within a glass yarn bundle that contains a longitudinal void
3.12
Leno end out
missing wrapper warp end from the edge of the fabric
3.13
lot
collection of units produced in one continuous, uninterrupted finish run from which a sample is
drawn and inspected or tested to determine conformance with the acceptability criteria.
3.14
mark
heavy or light area in fabric due to excessive or less filling yarns
3.14.1
heavy mark
filling defect extending across the width of the fabric containing two picks/inch in excess of the
nominal count
3.14.2
light mark
filling defect extending across the width of the fabric containing two picks/inch less than the
nominal count
3.15
pick
filling yarn running crosswise the entire width of a fabric
3.16
broken pick
filling yarn missing from a portion of the width of the fabric
3.17
mis-picks
break in the pattern of cloth from selvage to selvage caused by a missing filling yarn
3.18
plain weave
fabric configuration where each warp end should go over one pick and under the next, and each
pick should go over one warp end and under the next
3.19
split
opening in the fabric resulting from either the pick or end breaking in two
3.20
spread glass fabric
woven glass fabric, the warp and/or fill yarns of which, through mechanical action, are flattened
(spread out) such that the radial cross sectional aspect ratio (ratio of length of major and minor
axes) is increased and the percentage of open space between yarns per unit area is decreased,
as compared to a non-spread fabric of the same style

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IEC 61249-6-3:2023 © IEC 2023 – 9 –
3.21
TEX system
system for expressing linear density of yarn or other textile strand expressed as
grams/kilometer
3.22
waste
lump or collection of yarn or filament woven into the fabric where accumulated contamination
off the loom has found its way into the fabric
3.23
waviness
cloth is woven under varying tensions preventing even placement of picks resulting in
alternating thick and thin places
4 Visual requirements
When specified by purchase contract, the fabric is examined in accordance with 9.7.1. Visual
defects shall be identified and classified per Table 1 and meet the AQL defined in 9.6.3 and
9.6.4 as specified.
Table 1 – Classification of defects
Visual Defect Description Classification
Pick line distortion from horizontal by more than 2,5 %
a
Bias or bowed filling Major
for entire width
Baggy or wavy cloth Clearly noticeable per 9.7.1 Major
Cut or tear > 6,5 mm in any direction (body only) Major
Spots, streaks, stains, foreign
Clearly noticeable Major
inclusions
Broken or missing ends or
2 or more continuous, regardless of length Major
picks
Light marks > 6,5 mm in width Major
2 picks/2,54 cm less than nominal Minor
Heavy marks Puckering clearly noticeable Major
2 picks/2,54 cm more than nominal Minor
Crease Hard embedded and folded over on self Major
Waste Clearly noticeable > 6,5 mm Major
Clearly noticeable ≤ 6,5 mm Minor
Weave separation Clearly noticeable >3,175 mm Major
Leno ends out >5 m Major
≤5 m Minor
Feather length >5 mm running >4,5 m Major
>5 mm running ≤4,5 m Minor
a
It is important that as a target for the future, the non-homogeneous bow (i.e., a bow not stretching across the
width of material) should be reduced.

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– 10 – IEC 61249-6-3:2023 © IEC 2023
5 Physical requirements
5.1 Fabric count
Fabric count shall be evaluated in accordance with 9.7.2. The nominal fabric count for each
style shall be as specified in Annex A. For fabrics not listed, the nominal fabric count shall be
as agreed upon between user and supplier. The actual average count of warp ends or filling
picks shall be within ± 2/2,54 cm of the nominal count.
5.2 Weave type
Weave type shall be determined in accordance with 9.7.3. This specification only addresses
plain weave.
5.3 Fabric thickness
Fabric thickness shall be determined in accordance with 9.7.4. The nominal fabric thickness for
each style shall be as specified in Annex A.
5.4 Fabric weight
Fabric weight shall be determined in accordance with 9.7.5. The nominal fabric weight for each
style shall be as specified in Annex A and shall meet the tolerance listed.
5.5 Fabric length
Fabric length shall be determined in accordance with 9.7.6 and shall be as specified on the
purchase order. The length of the fabric shall be within ± 1 % of the value specified.
5.6 Fabric width
Fabric width shall be determined in accordance with 9.7.7 and shall be as specified on the
purchase order. The width of the fabric shall be within (-0/+13) mm of the value specified. If the
fabric has coated and cut (C&C) edges, the width shall be within (-0/+5) mm of the value
specified.
5.7 Feather length
The feather length shall not exceed 5,0 mm.
5.8 Filament diameter
The nominal filament diameter and the range of averages for products used in electrical
laminates are as given in Table 2. The filament diameters are to be certified by the yarn supplier
when requested.
Table 2 – Filament diameter designations
Designation Nominal diameter Range of averages
(SI) (μm) (μm)
4 4 3,50 to 4,70
4,5 4,5 3,56 to 5,08
5 5 4,80 to 5,87
6 6 5,84 to 7,16
7 7 6,40 to 7,82
9 9 8,46 to 10,34

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IEC 61249-6-3:2023 © IEC 2023 – 11 –
5.9 Bare glass nominal measurement
Bare glass nominal measurement (meters) shall be as defined in Table 3.
Table 3 – Bare glass nominal measurements
Yarn Nominal length per unit weight
SI Nomenclature SI (m/kg)

4 1,65 1x0 604,773
4 2,20 1x0 453,571
4 3,31 1x0 302,385
4,5 2,76 1x0 362,864
4,5 4,13 1x0 241,905
a
5 2,75 1x0 362,864
5 5,5 1x0 181,432
6 8,27 1x0 120,955
5 11 1x0 90,716
6 16,5 1x0 60,477
5 22 1x0 45,358
7 22 1x0 45,358
9 33 1x0 30,239
6 33 1x0 30,239
7 41 1x0 25,199
7 45 1x0 22,175
6 49 1x0 20,159
9 68 1x0 14,716
9 74 1x0 13,507
9 99 1x0 10,080
9 134 1x0 7,459
a
1/0 or 1x0 = Single yarn which has not been combined.

6 Chemical requirements
The finish level of the fabric shall be determined in accordance with 9.7.8. The organic content
of the finish fabric shall be no less than 0,05 % and no more than 0,30 %, unless otherwise
agreed upon between user and supplier.
7 Electrical requirements
7.1 Dielectric constant
The dielectric constant of bulk form E-glass when measured at 1 GHz shall be 7,1 +/-0,3 units
when tested using parallel plate analysis or equivalent.
7.2 Dissipation factor
The dissipation factor when measured at 1 GHz shall be as agreed upon between user and
supplier.

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– 12 – IEC 61249-6-3:2023 © IEC 2023
8 Workmanship requirements
8.1 Splices
Unless otherwise specified, the maximum allowable number of splices is one per 915 m, with a
minimum length between splices of 137 m. All splices shall be flagged and compatible with resin
solvents. Splices shall not lose strength and shall withstand treater stresses.
8.2 Laser machinability performance
Laser machinability performance is recognized as a significa
...