General Information

Abstract

This part of IEC 61249 specifies requirements for properties of polytetrafluoroethylene (PTFE) filled unreinforced laminated sheet of a thickness 0,02 mm up to 3,2 mm, of defined flammability (vertical burning test), copper-clad.
This document is applicable to the design, manufacture, use of PTFE filled unreinforced laminated sheet of defined flammability (vertical burning test), copper-clad.
Its flame resistance is defined in terms of the flammability requirements of 8.3.

Status
Published
Public Enquiry End Date
31-May-2025
Publication Date
19-Aug-2026
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
14-Jul-2026
Due Date
18-Sep-2026
Completion Date
20-Aug-2026

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SIST EN IEC 61249-3-6:2026

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Overview

SIST EN IEC 61249-3-6:2026 specifies critical requirements for PTFE-filled laminate sheets, both copper-clad and unclad, intended for use in printed boards and other interconnecting structures. This standard ensures materials meet stringent criteria for defined flammability, assessed by the vertical burning test, making it vital for the electronics industry where safety and high reliability are essential. By complying with this specification, manufacturers and users can achieve consistent performance, safety, and regulatory alignment in high-quality electronic assemblies.

Key Topics

  • Material Composition

    • PTFE (polytetrafluoroethylene) or modified PTFE resin is the primary base material, filled with additives such as silicon dioxide, titanium dioxide, or other approved fillers to reach desired characteristics.
    • Laminates are available clad with copper foil, meeting IEC 61249-5-1 standards.
    • No reinforcement materials are permitted for these unreinforced base laminates.
  • Flammability & Safety

    • Vertical burning test (IEC 61189-2) defines flammability performance, with V-0 performance required unless otherwise agreed.
    • Limits on flaming combustion time and prevention of flaming particles ensure safety in use.
  • Electrical Performance

    • High surface and volume resistivity maintained under humid and thermal stress conditions.
    • Defined values for relative permittivity and dissipation factor at microwave frequencies for consistent electrical behavior.
    • Requirements for arc resistance, dielectric breakdown, and electric strength (where relevant).
  • Physical & Mechanical Properties

    • Strict tolerances for laminate thickness, bow and twist, and dimensional stability.
    • Comprehensive requirements for copper foil adhesion, including peel strength after thermal and solvent exposure.
    • Criteria for defect levels in copper-clad and unclad surfaces, including limits for indentations, raised areas, and foreign inclusions.
  • Quality Assurance

    • Adherence to recognized quality management systems (ISO 9001) and environmental management practices (ISO 14001).
    • Procedures for qualification and ongoing conformance inspections, with documentation and certificate of conformance.

Applications

PTFE-filled, copper-clad laminates specified in this standard are critical in the design and manufacture of:

  • Printed Circuit Boards (PCBs):

    • Used where high frequency, low signal loss, and stable dielectric properties are needed.
    • Essential for microwave and RF circuit applications due to defined permittivity and low dissipation factors.
  • High-Reliability Electronic Assemblies:

    • Applicable in aerospace, telecommunications, medical, and automotive sectors where stringent flammability and electrical standards must be met.
  • Custom Interconnecting Structures:

    • Suitable for use in custom modules and connectors where safety, stability, and performance at elevated temperatures are demanded.

Related Standards

For comprehensive material and product compliance, users should be aware of related and supporting standards, such as:

  • IEC 61189-2 – Test methods for electrical materials, printed boards, and assemblies.
  • IEC 61189-2-721 – Measurement of relative permittivity and loss tangent at microwave frequency.
  • IEC 61189-2-803/805/807 – Test methods for dimensional stability, Z-axis, and X/Y-axis CTE, decomposition temperature.
  • IEC 61249-5-1 – Requirements for copper foils used in the manufacturing of copper-clad base materials.
  • ISO 11014 – Safety data sheet requirements for chemical products.

PTFE-filled copper-clad laminates meeting SIST EN IEC 61249-3-6:2026 guarantee enhanced safety, performance consistency, and global compliance for manufacturers and designers in the advanced electronics sector. Implementing this standard delivers proven reliability for demanding applications where material quality and flammability control are critical.

Relations

Effective Date
16-Jun-2026
Effective Date
16-Jun-2026
Effective Date
16-Jun-2026
Effective Date
16-Jun-2026
Effective Date
16-Jun-2026
Effective Date
16-Jun-2026

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SIST EN IEC 61249-3-6:2026

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Frequently Asked Questions

SIST EN IEC 61249-3-6:2026 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Materials for printed boards and other interconnecting structures - Part 3-6: Sectional specification set for unreinforced base materials, clad and unclad - PTFE filled laminate sheets of defined flammability (vertical burning test), copper-clad". This standard covers: This part of IEC 61249 specifies requirements for properties of polytetrafluoroethylene (PTFE) filled unreinforced laminated sheet of a thickness 0,02 mm up to 3,2 mm, of defined flammability (vertical burning test), copper-clad. This document is applicable to the design, manufacture, use of PTFE filled unreinforced laminated sheet of defined flammability (vertical burning test), copper-clad. Its flame resistance is defined in terms of the flammability requirements of 8.3.

This part of IEC 61249 specifies requirements for properties of polytetrafluoroethylene (PTFE) filled unreinforced laminated sheet of a thickness 0,02 mm up to 3,2 mm, of defined flammability (vertical burning test), copper-clad. This document is applicable to the design, manufacture, use of PTFE filled unreinforced laminated sheet of defined flammability (vertical burning test), copper-clad. Its flame resistance is defined in terms of the flammability requirements of 8.3.

SIST EN IEC 61249-3-6:2026 is classified under the following ICS (International Classification for Standards) categories: 31.180 - Printed circuits and boards. The ICS classification helps identify the subject area and facilitates finding related standards.

SIST EN IEC 61249-3-6:2026 has the following relationships with other standards: It is inter standard links to SIST EN IEC 61189-2-805:2025, SIST EN IEC 61189-2-803:2023, SIST EN 61189-2-721:2015, SIST EN 61189-2:2006, SIST EN IEC 61189-2-807:2021, SIST EN 61249-5-1:2001. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

SIST EN IEC 61249-3-6:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


SLOVENSKI STANDARD
01-september-2026
Materiali za plošče tiskanih vezij in druge povezovalne strukture - 3-6. del: Nabor
področnih specifikacij za ojačane podložne materiale, pokovinjene in
nepokovinjene -Llaminatne plošče z določeno vnetljivostjo, polnjene s
politetrafluoretilenom (preskus navpične gorljivosti), z bakreno oblogo
Materials for printed boards and other interconnecting structures - Part 3-6: Sectional
specification set for unreinforced base materials, clad and unclad - PTFE filled laminate
sheets of defined flammability (vertical burning test), copper-clad
Materialien für Leiterplatten und andere Verbindungsstrukturen - Teil 3-6:
Rahmenspezifikationen für unverstärkte Basismaterialien, kaschierte und unkaschierte
ungefüllte PTFE-Laminatplatten mit definierter Brennbarkeit (Brennprüfung mit vertikaler
Prüflingslage), kupferkaschiert
Matériaux pour circuits imprimés et autres structures d’interconnexion - Partie 3-6:
Collection de spécifications intermédiaires pour matériaux de base non renforcés,
métallisés et non métallisés - Feuilles stratifiées en PTFE avec charges d’inflammabilité
définie (essai de combustion verticale), plaquées cuivre
Ta slovenski standard je istoveten z: EN IEC 61249-3-6:2026
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 61249-3-6

NORME EUROPÉENNE
EUROPÄISCHE NORM July 2026
ICS 31.180
English Version
Materials for circuit boards and other interconnecting structures -
Part 3-6: Sectional specification set for unreinforced base
materials clad and unclad - Polytetrafluoroethylene (PTFE) filled
laminate sheets of defined flammability (vertical burning test),
copper-clad
(IEC 61249-3-6:2026)
Matériaux pour circuits imprimés et autres structures Materialien für Leiterplatten und andere
d'interconnexion - Partie 3-6: Collection de spécifications Verbindungsstrukturen - Teil¿3 6:
intermédiaires pour matériaux de base non renforcés, Abschnittsspezifikationen für unverstärkte kaschierte und
métallisés et non métallisés - Feuilles stratifiées en ptfe unkaschierte Basismaterialien - PTFE gefüllte Laminattafeln
avec charges d'inflammabilité définie (essai de combustion mit definierter Brennbarkeit (vertikale Brandprüfung),
verticale), plaquées cuivre kupferkaschiert
(IEC 61249-3-6:2026) (IEC 61249-3-6:2026)
This European Standard was approved by CENELEC on 2026-06-23. 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
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61249-3-6:2026 E

European foreword
The text of document 91/2102/FDIS, future edition 1 of IEC 61249-3-6, prepared by TC 91 "Electronics
assembly technology" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC
as EN IEC 61249-3-6:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-07-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-07-31
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 61249-3-6:2026 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 60695-11-10 NOTE Approved as EN 60695-11-10
ISO 9001:2015 NOTE Approved as EN ISO 9001:2015 (not modified)
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 61189-2 - Test methods for electrical materials, printed EN 61189-2 -
boards and other interconnection structures and
assemblies - Part 2: Test methods for materials
for interconnection structures
IEC 61189-2-721 - Test methods for electrical materials, printed EN 61189-2-721 -
boards and other interconnection structures and
assemblies - Part 2-721: Test methods for
materials for interconnection structures -
Measurement of relative permittivity and loss
tangent for copper clad laminate at microwave
frequency using a split post dielectric resonator
IEC 61189-2-803 - Test methods for electrical materials, printed EN IEC 61189-2-803 -
boards and other interconnection structures and
assemblies - Part 2-803: Test methods for Z-
axis expansion of base materials and printed
boards
IEC 61189-2-805 - Test methods for electrical materials, printed EN IEC 61189-2-805 -
boards and other interconnection structures and
assemblies - Part 2-805: X/Y CTE test for thin
base materials by TMA
IEC 61189-2-807 - Test methods for electrical materials, printed EN IEC 61189-2-807 -
boards and other interconnection structures and
assemblies - Part 2-807: Test methods for
materials for interconnection structures -
Decomposition temperature (Td) using TGA
IEC 61249-5-1 - Materials for interconnection structures - Part 5: EN 61249-5-1 -
Sectional specification set for conductive foils
and films with and without coatings - Section 1:
Copper foils (for the manufacture of copper-clad
base materials)
ISO 11014 - Safety data sheet for chemical products - - -
Content and order of sections
IPC-TM-650 TM - Stripline Test for Permittivity and Loss Tangent - -
2.5.5.5 (Dielectric Constant and Dissipation Factor) at
X-Band
IEC 61249-3-6 ®
Edition 1.0 2026-05
INTERNATIONAL
STANDARD
Materials for circuit boards and other interconnecting structures -
Part 3-6: Sectional specification set for unreinforced base materials clad and
unclad - Polytetrafluoroethylene (PTFE) filled laminate sheets of defined
flammability (vertical burning test), copper-clad
ICS 31.180  ISBN 978-2-8327-1248-1

IEC 61249-3-6:2026-05(en)
IEC 61249-3-6:2026 © IEC 2026
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions. 6
3.2 Abbreviated terms . 6
4 Construction and materials . 6
4.1 Construction . 6
4.2 Resin system . 6
4.3 Filler . 6
4.4 Metal foil . 6
4.5 Reinforcement . 6
5 Internal marking . 6
6 Electrical properties . 6
7 Non-electrical properties of the base material . 7
7.1 Appearance of the copper-clad sheet . 7
7.1.1 General . 7
7.1.2 Indentations (pits and dents) . 7
7.1.3 Wrinkles . 8
7.1.4 Scratches . 8
7.1.5 Raised areas . 8
7.2 Appearance of the unclad face . 8
7.3 Laminate thickness . 9
7.4 Bow and twist . 9
7.5 Properties related to the copper foil bond . 9
7.6 Heat shock . 10
7.7 Machining . 10
7.8 Dimensional stability . 10
7.9 Sheet sizes and tolerances . 11
7.9.1 Typical sheet sizes . 11
7.9.2 Tolerances for sheet sizes . 11
7.10 Cut panels sizes, tolerances and rectangularity . 11
7.10.1 Cut panel sizes . 11
7.10.2 Size tolerances for cut panels . 11
7.10.3 Rectangularity of cut panels . 11
8 Non-electrical properties of the base material after complete removal of the
copper foil . 12
8.1 General . 12
8.2 Appearance of the dielectric base material . 12
8.3 Flammability . 12
8.4 Water absorption . 13
8.5 Glass transition temperature and cure factor . 13
8.6 Decomposition temperature . 13
8.7 Z-axis CTE . 13
8.8 X/Y-axis CTE . 13
8.9 Thermal conductivity . 14
IEC 61249-3-6:2026 © IEC 2026
9 Quality assurance . 14
9.1 Quality system . 14
9.2 Responsibility for inspection . 14
9.3 Qualification inspection . 14
9.3.1 General . 14
9.3.2 Samples . 14
9.3.3 Frequency . 14
9.3.4 Criterion rule . 14
9.4 Quality conformance inspection . 15
9.4.1 General . 15
9.4.2 Inspection lot . 15
9.4.3 Group A inspection . 15
9.4.4 Group B inspection . 15
9.4.5 Group C inspection . 16
9.4.6 Criterion rule . 16
9.4.7 Rejected lots . 16
9.5 Certificate of conformance . 16
9.6 Safety data sheet . 16
10 Packaging and marking . 16
11 Ordering information . 17
Annex A (informative) Engineering information . 18
A.1 General . 18
A.2 Electrical properties . 18
A.3 Non-electrical properties of the base material after complete removal of the
copper foil . 18
Bibliography . 19

Table 1 – Electrical properties . 7
Table 2 – Indentations . 8
Table 3 – Nominal thickness and tolerance of metal-clad laminate . 9
Table 4 – Bow and twist requirements . 9
Table 5 – Peel strength requirements . 10
Table 6 – Heat shock requirements . 10
Table 7 – Dimensional stability . 10
Table 8 – Size tolerances for cut panels . 11
Table 9 – Rectangularity of cut panels . 11
Table 10 – Flammability requirements . 12
Table 11 – Water absorption requirements . 13
Table 12 – Decomposition temperature requirements . 13
Table 13 – Z-axis CTE requirements . 13
Table 14 – X/Y-axis CTE requirements . 13
Table 15 – Qualification and conformance inspection . 14

IEC 61249-3-6:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Materials for circuit boards and other interconnecting structures -
Part 3-6: Sectional specification set for unreinforced base materials clad
and unclad - Polytetrafluoroethylene (PTFE) filled laminate sheets of
defined flammability (vertical burning test), copper-clad

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
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
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
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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) 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 61249-3-6 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
91/2102/FDIS 91/2110/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 61249-3-6:2026 © IEC 2026
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.
A list of all parts in the IEC 61249 series, published under the general title Materials for circuit
boards and other interconnecting structures, 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, or
– revised.
IEC 61249-3-6:2026 © IEC 2026
1 Scope
This part of IEC 61249 specifies requirements for properties of polytetrafluoroethylene (PTFE)
filled unreinforced laminated sheet of a thickness 0,02 mm up to 3,2 mm, of defined flammability
(vertical burning test), copper-clad.
This document is applicable to the design, manufacture, use of PTFE filled unreinforced
laminated sheet of defined flammability (vertical burning test), copper-clad.
Its flame resistance is defined in terms of the flammability requirements of 8.3.
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 61189-2, Test methods for electrical materials, printed boards and other interconnection
structures and assemblies - Part 2: Test methods for materials for interconnection structures
IEC 61189-2-721, Test methods for electrical materials, printed board and other interconnection
structures and assemblies - Part 2-721: Test methods for materials for interconnection
structures - Measurement of relative permittivity and loss tangent for copper clad laminate at
microwave frequency using split post dielectric resonator
IEC 61189-2-803, Test methods f
...