IEC 61249-4-5:2005

Materials for printed boards and other interconnecting structures - Part 4-5: Sectional specification set for prepreg materials, unclad - Polyimide, modified or unmodified, woven E-glass prepreg of defined flammability

This part of IEC 61249 gives requirements for properties of prepreg that is mainly intended to be used as bonding sheets in connection with laminates according to IEC 61249-2-8 when manufacturing multilayer boards according to IEC 62326-4. This material may be also used to bond other types of laminates. Prepreg according to this standard is of defined flammability (vertical burning test). The flammability rating on fully cured prepreg is achieved through the use of brominated fire retardants contained as an integral part of the polymeric structure. After curing of the prepreg according to the supplier's instructions, the glass transition temperature is defined as 150 °C minimum.

General Information

• Status: Published
• Publication Date: 04-Sep-2005
• ICS: 31.180 - Printed circuits and boards
• Technical Committee: TC 91 - Electronics assembly technology
• Drafting Committee: WG 4 - TC 91/WG 4
• Current Stage: PPUB - Publication issued
• Start Date: 05-Sep-2005
• Completion Date: 15-Dec-2005

Overview

IEC 61249-4-5:2005 is an international sectional specification for polyimide, modified or unmodified, woven E‑glass prepreg of defined flammability used as unclad bonding sheets in multilayer printed boards. The standard defines material construction, appearance and cured properties, flammability classification (vertical burning test), delivery forms (rolls, sheets, cut panels), quality assurance and ordering information. The published text specifies a minimum glass transition temperature (Tg) for fully cured material of 170 °C and uses brominated flame retardants incorporated in the polymeric structure to achieve the defined flammability rating.

Key topics and requirements

• Materials and construction
  • Reinforcement: woven E‑glass fabric (per IEC 61249-6-3)
  • Resin system: polyimide (modified or unmodified) impregnated and B‑staged
• Thermal and electrical properties
  • Glass transition temperature (Tg): 170 °C minimum (after curing per supplier instructions)
  • Electric strength after cure: minimum 25 V/µm (measured on bonded plies)
• Flammability
  • Defined by a vertical burning test on cured specimens; flame resistance provided by brominated retardants integral to the resin
• B‑stage and process parameters (examples and tolerances)
  • Resin content: typical tolerance ±3%
  • Treated weight: typical tolerance ±3%
  • Resin flow: typical tolerance ±5%
  • Melt viscosity and gel time are specified by agreement between user and supplier (example tolerances provided in the document)
  • Volatile content ≤ 2% (maximum)
• Appearance and mechanical limits
  • Dewetted areas (“fish eyes”) > 10 mm not permitted; ≤10 mm limited to 10 per 300 × 300 mm
  • Distortion/non‑perpendicular yarn orientation ≤ 10% over 300 mm
  • Creases exposing glass yarns are not permitted; edge resin loss due to cutting ≤ 2 mm
• Quality and supply
  • Requirements for quality systems, qualification and conformance inspection, certificate of conformance, SDS, packaging, shelf life and ordering data

Applications and users

• Primary use: bonding sheets for laminating multilayer PCBs (in conjunction with laminates per IEC 61249-2-11 and multilayer board spec IEC 62326-4)
• Also used to bond other laminate types where a high‑temperature, flame‑retardant polyimide prepreg is required
• Typical users: PCB manufacturers, laminate and prepreg suppliers, materials engineers, process/quality engineers, procurement and compliance teams in electronics assembly and aerospace/industrial sectors

Related standards

• IEC 61189-2 (test methods for materials)
• IEC 61249-2-11 (polyimide laminated sheet)
• IEC 61249-6-3 (woven E‑glass reinforcement)
• IEC 62326-4 (rigid multilayer printed boards)
• ISO 9000, ISO 14001, ISO 11014-1 (quality, environment, safety data sheets)

Keywords: IEC 61249-4-5, polyimide prepreg, woven E‑glass, flame retardant prepreg, prepreg materials, multilayer PCB bonding sheet, glass transition temperature, vertical burning test.

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD 61249-4-5
First edition
2005-09
Materials for printed boards and
other interconnecting structures –
Part 4-5:
Sectional specification set for prepreg materials,
unclad – Polyimide, modified or unmodified,
woven E-glass prepreg of defined flammability
Reference number
Publication numbering
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60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
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INTERNATIONAL IEC
STANDARD 61249-4-5
First edition
2005-09
Materials for printed boards and
other interconnecting structures –
Part 4-5:
Sectional specification set for prepreg materials,
unclad – Polyimide, modified or unmodified,
woven E-glass prepreg of defined flammability

 IEC 2005  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale M
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – 61249-4-5  IEC:2005(E)
CONTENTS
FOREWORD.3

1 Scope.5
2 Normative references .5
3 Materials and construction.6
3.1 Reinforcement.6
3.2 Resin system.6
4 Properties.6
4.1 Properties related to the appearance of the prepreg .6
4.2 Properties related to B-stage prepreg.7
4.3 Properties related to prepreg after curing .8
5 Delivery form .9
5.1 Rolls.9
5.2 Sheets.9
5.3 Cut panels.10
6 Quality assurance.10
6.1 Quality system.10
6.2 Responsibility for inspection .10
6.3 Qualification inspection .10
6.4 Quality conformance inspection.10
6.5 Certificate of conformance.10
6.6 Safety data sheet .10
7 Packaging and marking .11
8 Shelf life.11
9 Ordering information.11

Bibliography.13

Table 1 – Flammability.9

61249-4-5  IEC:2005(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
MATERIALS FOR PRINTED BOARDS AND
OTHER INTERCONNECTING STRUCTURES –

Part 4-5: Sectional specification for prepreg materials, unclad –
Polyimide, modified or unmodified, woven E-glass prepreg
of defined flammability
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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) 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.
International Standard IEC 61249-4-5 has been prepared by IEC technical committee 91:
Electronics assembly technology.
The text of this standard is based on the following documents:
FDIS Report on voting
91/527/FDIS 91/537/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 61249-4-5  IEC:2005(E)
IEC 61249-4 consists of the following parts, under the general title Materials for printed
boards and other interconnecting structures – Part 4: Sectional specification set for prepreg
materials, unclad:
Part 4-1: Epoxide woven E-glass prepreg of defined flammability
Part 4-2: Multifunctional epoxide woven E-glass prepreg of defined flammability
Part 4-5: Polyimide, modified or unmodified, woven E-glass prepreg of defined flammability
Part 4-11: Non-halogenated epoxide, woven E-glass prepreg of defined flammability
Part 4-12: Non-halogenated multifunctional epoxide woven E-glass prepreg of defined
flammability
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

———————
Under consideration.
61249-4-5  IEC:2005(E) – 5 –
MATERIALS FOR PRINTED BOARDS AND
OTHER INTERCONNECTING STRUCTURES –

Part 4-5: Sectional specification set for prepreg materials, unclad –
Polyimide, modified or unmodified, woven E-glass prepreg
of defined flammability
1 Scope
This part of IEC 61249 gives requirements for properties of prepreg that is mainly intended to
be used as bonding sheets in connection with laminates according IEC 61249-2-11 when
manufacturing multilayer boards according to IEC 62326-4. This material may be also used to
bond other types of laminates.
Prepreg according to this standard is of defined flammability (vertical burning test). The
flammability rating on fully cured prepreg is achieved through the use of brominated fire
retardants contained as an integral part of the polymeric structure. After curing according to
the supplier’s instructions, the glass transition temperature is defined to be 170 °C minimum.
2 Normative references
The following referenced documents are indispensable for the application 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 61189-2:1997, Test methods for electrical materials, printed boards and other inter-
connecting structures and assemblies – Part 2: Test methods for materials for interconnection
structures
Amendment 1 (2000)
IEC 61249-2-11, Materials for printed boards and other interconnecting structures – Part 2-11:
Sectional specification set for reinforced base materials clad and unclad – Polyimide woven
E-glass laminated sheet of defined flammability copper-clad
IEC 61249-6-3, Material for printed boards and other interconnecting structures – Part 6-3:
Sectional specification set for reinforcement materials – Woven E-glass (for t
...