SIST EN IEC 61249-3-6:2026

• Status: Not Published
• Public Enquiry End Date: 31-May-2025
• ICS: 31.180 - Printed circuits and boards
• Technical Committee: ITIV - Electronics assembly technology and Environmental standardization
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 14-Jul-2026
• Due Date: 18-Sep-2026
• Ref Project: EN IEC 61249-3-6:2026 - 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

• Refers: SIST EN IEC 61189-2-805:2025 - Test methods for electrical materials, printed board and other interconnection structures and assemblies - Part 2-805: X/Y CTE Test for Thin Base Materials by TMA
• Effective Date: 16-Jun-2026
• Refers: SIST EN IEC 61189-2-803:2023 - Test methods for electrical materials, printed board and other interconnection structures and assemblies - Part 2-803: Test methods for Z-Axis Expansion of base materials and printed board
• Effective Date: 16-Jun-2026
• Refers: SIST EN 61189-2-721:2015 - Test methods for electrical materials, printed 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 Split Post Dielectric Resonator
• Effective Date: 16-Jun-2026
• Refers: SIST EN 61189-2:2006 - Test methods for electrical materials, printed boards and other interconnection structures and assemblies -- Part 2: Test methods for materials for interconnection structures
• Effective Date: 16-Jun-2026
• Refers: SIST EN IEC 61189-2-807:2021 - Test methods for electrical materials, printed board and other interconnection structures and assemblies - Part 2-807: Test methods for materials for interconnection structures - Decomposition Temperature (Td) using TGA
• Effective Date: 16-Jun-2026
• Refers: SIST EN 61249-5-1:2001 - Materials for interconnection structures -- Part 5: Sectional specification set for conductive foils and films with or without coatings - Section 1: Copper foils (for the manufacture of copper-clad base materials)
• Effective Date: 16-Jun-2026

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.

SLOVENSKI STANDARD
oSIST prEN IEC 61249-3-6:2025
01-maj-2025
Materiali za plošče tiskanih vezij in druge povezovalne strukture - 3-6. del: Nabor
področnih specifikacij za ojačane podložne materiale, pokovinjene in
nepokovinjene - laminatne plošče z določeno vnetljivostjo, polnjene s
politetrafluoretilenom (navpični preskus 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
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: prEN IEC 61249-3-6:2025
ICS:
31.180 Tiskana vezja (TIV) in tiskane Printed circuits and boards
plošče
oSIST prEN IEC 61249-3-6:2025 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 61249-3-6:2025
oSIST prEN IEC 61249-3-6:2025
91/2015/CDV
COMMITTEE DRAFT FOR VOTE (CDV)

PROJECT NUMBER:
IEC 61249-3-6 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-03-14 2025-06-06
SUPERSEDES DOCUMENTS:
91/1956/CD, 91/1992/CC
IEC TC 91 : ELECTRONICS ASSEMBLY TECHNOLOGY
SECRETARIAT: SECRETARY:
Japan Mr Osamu IKEDA
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some
Countries” clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is
the final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
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

PROPOSED STABILITY DATE: 2031
NOTE FROM TC/SC OFFICERS:
download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National
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oSIST prEN IEC 61249-3-6:2025
IEC CDV 61249-3-6 © IEC 2025 – 2 – 91/2015/CDV
1 CONTENTS
3 FOREWORD . 4
4 1 Scope . 6
5 2 Normative references . 6
6 3 Terms and definitions . 6
7 4 Construction and Materials . 7
8 4.1 Construction . 7
9 4.2 Resin system . 7
10 4.3 Filler . 7
11 4.4 Metal foil . 7
12 4.5 Reinforcement . 7
13 5 Internal marking . 7
14 6 Electrical properties . 7
15 7 Non-electrical properties of the base material . 8
16 7.1 Appearance of the copper-clad sheet . 8
17 7.1.1 General . 8
18 7.1.2 Indentations (pits and dents) . 8
19 7.1.3 Wrinkles . 9
20 7.1.4 Scratches . 9
21 7.1.5 Raised areas . 9
22 7.2 Appearance of the unclad face . 9
23 7.3 Laminate thickness . 9
24 7.4 Bow and twist . 10
25 7.5 Properties related to the copper foil bond . 10
26 7.6 Heat shock . 10
27 7.7 Machining . 11
28 7.8 Dimensional stability . 11
29 7.9 Sheet sizes and tolerances . 11
30 7.9.1 Typical sheet sizes . 11
31 7.9.2 Tolerances for sheet sizes . 11
32 7.10 Cut panels sizes, tolerances and rectangularity . 11
33 7.10.1 Cut panel sizes . 11
34 7.10.2 Size tolerances for cut panels . 12
35 7.10.3 Rectangularity of cut panels . 12
36 8 Non-electrical properties of the base material after complete removal of the
37 copper foil . 12
38 8.1 Appearance of the dielectric base material . 12
39 8.2 Flammability . 13
40 8.3 Water absorption . 13
41 8.4 Glass transition temperature and cure factor . 13
42 8.5 Decomposition temperature . 13
43 8.6 Z-axis CTE . 13
44 8.7 X/Y-axis CTE . 14
45 8.8 Thermal Conductivity . 14
46 9 Quality assurance . 14
47 9.1 Quality system . 14

oSIST prEN IEC 61249-3-6:2025
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48 9.2 Responsibility for inspection . 14
49 9.3 Qualification inspection . 14
50 9.3.1 General . 14
51 9.3.2 Samples . 14
52 9.3.3 Frequency . 14
53 9.3.4 Criterion Rule . 14
54 9.4 Quality Conformance inspection . 15
55 9.4.1 General . 15
56 9.4.2 Inspection lot . 15
57 9.4.3 Group A inspection . 15
58 9.4.4 Group B inspection . 16
59 9.4.5 Group C inspection . 16
60 9.4.6 Criterion Rule . 16
61 9.4.7 Rejected lots . 16
62 9.5 Certificate of conformance . 16
63 9.6 Safety data sheet . 16
64 10 Packaging and marking . 16
65 11 Ordering information . 16
66 Annex A (informative)  Engineering information . 18
67 A.1 General . 18
68 A.2 Electrical properties . 18
69 A.3 Non-electrical properties of the base material after complete removal of the
70 copper foil . 18
71 Bibliography . 19
73 Table 1 – Electrical properties . 7
74 Table 2 – Indentations . 8
75 Table 3 – Nominal thickness and tolerance of metal-clad laminate . 9
76 Table 4 – Bow and twist requirements . 10
77 Table 5 – Peel strength requirements . 10
78 Table 6 – Heat shock requirements . 11
79 Table 7 – Dimensional stability . 11
80 Table 8 – Size tolerances for cut panels . 12
81 Table 9 – Rectangularity of cut panels . 12
82 Table 10 – Flammability requirements . 13
83 Table 11 – Water absorption requirements . 13
84 Table 12 – Decomposition temperature requirements . 13
85 Table 13 – Z-axis CTE requirements . 14
86 Table 14 – X/Y-axis CTE requirements . 14
87 Table 15 – Qualification and conformance inspection . 15
oSIST prEN IEC 61249-3-6:2025
IEC CDV 61249-3-6 © IEC 2025 – 4 – 91/2015/CDV
90 INTERNATIONAL ELECTROTECHNICAL COMMISSION
91 ____________
93 MATERIALS FOR CIRCUIT BOARDS AND OTHER INTERCONNECTING
94 STRUCTURES –
96 Part 3-6: Unreinforced base materials clad and unclad - PTFE filled
97 laminate sheets of defined flammability (vertical burning test), copper-
98 clad
102 FOREWORD
103 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
104 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
105 co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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111 Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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130 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
131 indispensable for the correct application of this publication.
132 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
133 rights. IEC shall not be held responsible for identifying any or all such patent rights.
134 International Standard IEC 61249-X-X has been prepared by IEC technical committee 91,
135 Electronics assembly technology.
136 The text of this International Standard is based on the following documents:
FDIS Report on voting
XX/XX/FDIS XX/XX/RVD
138 Full information on the voting for the approval of this International Standard can be found in the
139 report on voting indicated in the above table.
140 This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

oSIST prEN IEC 61249-3-6:2025
IEC CDV 61249-3-6 © IEC 2025 – 5 – 91/2015/CDV
141 The committee has decided that the contents of this document will remain unchanged until the
142 stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
143 the specific document. At this date, the document will be
144 • reconfirmed,
145 • withdrawn,
146 • replaced by a revised edition, or
147 • amended.
149 The National Committees are requested to note that for this document the stability date
150 is 20XX.
151 THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE DELETED
152 AT THE PUBLICATION STAGE.
oSIST prEN IEC 61249-3-6:2025
IEC CDV 61249-3-6 © IEC 2025 – 6 – 91/2015/CDV
155 MATERIALS FOR CIRCUIT BOARDS AND OTHER INTERCONNECTING
156 STRUCTURES –
158 Part 3-6: Unreinforced base materials clad and unclad - PTFE filled
159 laminate sheets of defined flammability (vertical burning test), copper-
160 clad
164 1 Scope
165 This part of IEC 61249 specifies requirements for properties of PTFE filled unreinforced
166 laminated sheet of a thickness 0,02 mm up to 3,2 mm, of defined flammability (vertical burning
167 test), copper-clad.
168 This part of IEC 61249 is applicable to the design, manufacture, use of PTFE filled unreinforced
169 laminated sheet of defined flammability (vertical burning test), copper-clad.
170 Its flame resistance is defined in terms of the flammability requirements of 8.2.
171 2 Normative references
172 The following documents are referred to in the text in such a way that some or all of their content
173 constitutes requirements of this document. For dated references, only the edition cited applies.
174 For undated references, the latest edition of the referenced document (including any
175 amendments) applies.
176 IEC 61189-2:2006, Test methods for electrical materials, printed boards and other
177 interconnection structures and assemblies – Part 2: Test methods for materials for
178 interconnection structures
179 IEC 61189-2-721:2015, Test methods for electrical materials, printed board and other
180 interconnection structures and assemblies - Part 2-721: Test methods for materials for
181 interconnection structures – Measurement of relative permittivity and loss tangent for copper
182 clad laminate at microwave frequency using split post dielectric resonator
183 IEC 61189-2-803:2023, Test methods for electrical materials, printed board and other
184 interconnection structures and assemblies - Part 2-803: Test methods for materials for
185 interconnection structures - Test methods for Z-axis expansion of base materials and printed
186 boards
187 IEC 61189-2-805:20XX, Test methods for electrical materials, printed board and other
188 interconnection structures and assemblies – Part 2-805: Test methods for materials for
189 interconnection structures - X/Y CTE Test for Thin Base Materials by TMA
190 IEC 61189-2-807:2021, Test methods for electrical materials, printed board and other
191 interconnection structures and assemblies - Part 2-807: Test methods for materials for
192 interconnection structures – Decomposition temperature (Td) using TGA
193 IEC 61249-5-1, Materials for interconnection structures – Part 5: Sectional specification set for
194 conductive foils and films with or without coatings – Section 1: Copper foils (for the manufacture
195 of copper-clad base materials)
196 ISO 11014:2009, Safety data sheet for chemical products – Content and order of sections
197 IPC TM-650 TM 2.5.5.5, Stripline Test for Permittivity and Loss Tangent (Dielectric Constant
198 and Dissipation Factor) at X-Band
199 3 Terms and definitions
200 For the purposes of this document, the following terms and definitions apply.

oSIST prEN IEC 61249-3-6:2025
IEC CDV 61249-3-6 © IEC 2025 – 7 – 91/2015/CDV
201 ISO and IEC maintain terminology databases for use in standardization at the following
202 addresses:
203 • IEC Electropedia: available at http://www.electropedia.org/
204 • ISO Online browsing platform: available at http://www.iso.org/obp
205 3.1
206 PTFE
207 polytetrafluoroethylene
208 4 Construction and Materials
209 4.1 Construction
210 The sheet consists of an insulating base made of PTFE or modified PTFE as the primary resin,
211 with metal-foil bonded to one side or both.
212 4.2 Resin system
213 PTFE resin or modified PTFE as the primary resin, and have filler addition.
214 4.3 Filler
215 Typical filling (filler) materials can be silicon dioxide, titanium dioxide, aluminium oxide, boron
216 nitride, chopped fiber, hollow sphere. It is possible to use other or additional filling material to
217 achieve specific characteristic.
218 4.4 Metal foil
219 Copper, as specified in IEC 61249-5-1, copper foil (for the manufacture of copper-clad
220 materials). The preferred foils are electrodeposited of defined ductility.
221 4.5 Reinforcement
222 None Reinforcement.
223 5 Internal marking
224 Shall be as agreed upon between user and supplier.
225 6 Electrical properties
226 The electrical properties requirements are shown in Table 1.
227 Table 1 – Electrical properties
Property Test method Units Requirement
Surface resistivity after damp
heat while in the humidity IEC 61189-2 2E04 MΩ ≥10000
chamber
Volume resistivity after damp
heat while in the humidity IEC 61189-2 2E04 MΩ·m ≥5000
chamber
Surface resistivity after E-24/125
IEC 61189-2 2E04 MΩ ≥1000
while in the chamber
Volume resistivity after E-24/125
MΩ·m
IEC 61189-2 2E04 ≥1000
while in the chamber
Type A：≤2,75
Type B：>2,75 ≤6,00
Relative permittivity as received IPC
...