IEC 61249-3-4:1999

Materials for printed boards and other interconnecting structures - Part 3-4: Sectional specification set for unreinforced base materials, clad and unclad (intended for flexible printed boards) - Adhesive coated flexible polyimide film

Gives requirements for flexible polyimide films coated on one side or both sides with acrylic or epoxide type adhesive for use in the fabrication of flexible printed wiring. Films coated on only one side are used as a coverlay or covercoat in the fabrication of flexible printed wiring. This coverlay or covercoat is also used to provide local support to areas subjected to mechanical or environmental stress. Films coated on both sides are used as bonding films in the fabrication of printed boards.

Matériaux pour circuits imprimés et autres structures d'interconnexion - Partie 3-4: Collection de spécifications intermédiaires pour les matériaux de base non renforcés, recouverts ou non (prévus pour les circuits imprimés flexibles) - Film flexible polyimide à revêtement adhésif

Donne les prescriptions pour les films flexibles polyimides recouverts d'un adhésif de type acrylique ou époxyde destinés à la fabrication des câblages imprimés souples.

General Information

• Status: Published
• Publication Date: 09-Feb-1999
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• 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: 28-Feb-1999
• Completion Date: 10-Feb-1999

Standards Content (Sample)

INTERNATIONAL
IEC
STANDARD
61249-3-4
First edition
1999-02
Materials for printed boards and
other interconnecting structures –
Part 3-4:
Sectional specification set for unreinforced
base materials, clad and unclad
(intended for flexible printed boards) –
Adhesive coated flexible polyimide film
Matériaux pour circuits imprimés et autres structures
d'interconnexion –
Partie 3-4:
Collection de spécifications intermédiaires pour les matériaux
de base non renforcés, recouverts ou non
(prévus pour les circuits imprimés flexibles) –
Film flexible de polyimide recouvert de colle
Reference number
Numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series.
Consolidated publications
Consolidated versions of some IEC publications including amendments are
available. For example, edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the
base publication, the base publication incorporating amendment 1 and the base
publication incorporating amendments 1 and 2.
Validity of this publication
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology.
Information relating to the date of the reconfirmation of the publication is available
in the IEC catalogue.
Information on the subjects under consideration and work in progress undertaken by
the technical committee which has prepared this publication, as well as the list of
publications issued, is to be found at the following IEC sources:
• IEC web site*
• Catalogue of IEC publications
Published yearly with regular updates
(On-line catalogue)*
• IEC Bulletin
Available both at the IEC web site* and as a printed periodical
Terminology, graphical and letter symbols
For general terminology, readers are referred to IEC 60050: International
Electrotechnical Vocabulary (IEV).
For graphical symbols, and letter symbols and signs approved by the IEC for
general use, readers are referred to publications IEC 60027: Letter symbols to be
used in electrical technology, IEC 60417: Graphical symbols for use on equipment.
Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols
for diagrams.
* See web site address on title page.

INTERNATIONAL
IEC
STANDARD
61249-3-4
First edition
1999-02
Materials for printed boards and
other interconnecting structures –
Part 3-4:
Sectional specification set for unreinforced
base materials, clad and unclad
(intended for flexible printed boards) –
Adhesive coated flexible polyimide film
Matériaux pour circuits imprimés et autres structures
d'interconnexion –
Partie 3-4:
Collection de spécifications intermédiaires pour les matériaux
de base non renforcés, recouverts ou non
(prévus pour les circuits imprimés flexibles) –
Film flexible de polyimide recouvert de colle
 IEC 1999  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 Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
N
International Electrotechnical Commission
For price, see current catalogue

– 2 – 61249-3-4 © IEC:1999(E)
CONTENTS
Page
FOREWORD . 3
Clause
1 Scope . 4
2 Normative reference. 4
3 Materials and construction. 4
4 Internal marking .5
5 Designation. 6
6 Properties of adhesive coated polyimide films. 6
7 Dimensions and tolerances . 9
8 Packaging and marking . 9
9 Acceptance testing. 10
Annex A (informative) Conversion table for test method reference numbers . 11

61249-3-4 © IEC:1999(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
–––––––––––
MATERIALS FOR PRINTED BOARDS AND OTHER
INTERCONNECTING STRUCTURES –
Part 3-4: Sectional specification set for unreinforced base materials,
clad and unclad (intended for flexible printed boards) –
Adhesive coated flexible polyimide film
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any divergence
between the IEC Standard and the corresponding national or regional standard shall be clearly indicated in the
latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61249-3-4 has been prepared by IEC technical committee 52:
Printed circuits.
The text of this standard is based on the following documents:
FDIS Report on voting
52/773/FDIS 52/798/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.
Annex A is for information only.
A bilingual version of this standard may be issued at a later date.

– 4 – 61249-3-4 © IEC:1999(E)
MATERIALS FOR PRINTED BOARDS AND OTHER
INTERCONNECTING STRUCTURES –
Part 3-4: Sectional specification set for unreinforced base materials,
clad and unclad (intended for flexible printed boards) –
Adhesive coated flexible polyimide film
1 Scope
This part of IEC 61249 gives requirements for flexible polyimide films coated on one side or
both sides with acrylic or epoxide type adhesive for use in the fabrication of flexible printed
wiring.
Films coated on only one side are used as a coverlay or covercoat in the fabrication of flexible
printed wiring. This coverlay or covercoat is also used to provide local support to areas
subjected to mechanical or environmental stress.
Films coated on both sides are used as bonding films in the fabrication of printed boards.
2 Normative reference
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61249. For dated references, subsequent amendments
to, or revisions of, any of these publications do not apply. However, parties to agreements
based on this part of IEC 61249 are encouraged to investigate the possibility of applying the
most recent editions of the normative documents indicated below. For undated references, the
latest edition of the normative document referred to applies. Members of IEC and ISO maintain
registers of currently valid International Standards.
IEC 61189-2:1997, Test methods for electrical materials, interconnection structures and
assemblies – Part 2: Test methods for materials for interconnection structures
3 Materials and construction
The material consists of an insulating flexible film base of polyimide coated with an adhesive
on one side or both sides.
3.1 Insulating film
Polyimide films of preferred thicknesses and permitted tolerances are given in table 1 when
measured by the method 2D01 of IEC 61189-2, provided that the micrometer used is capable
of resolving 0,002 mm or better.
Other thicknesses may be used by agreement between purchaser and supplier. The maximum
permitted tolerances of such thicknesses shall be those of the nearest greater thickness stated
in table 1.
61249-3-4 © IEC:1999(E) – 5 –
Table 1 – Preferred thicknesses and maximum permitted tolerances
Nominal thickness Maximum tolerance
(without adhesive) at any measured point
%
μm
12,5 ± 30
25 ± 20
50 ± 15
75 ± 10
125 ± 10
3.2 Adhesive
The adhesive shall be compatible with the copper-clad polyimide film. Relevant adhesives are
B-staged adhesives based on acrylic or epoxy resin.
The thickness of the adhesive is defined as follows:
T = T – T
a c f
where
T is the thickness of the adhesive;
a
T is the average value of the total thickness of the adhesive coated film under test;
c
T is the average value of the thicknesses of the insulation film under test without adhesive.
f
Thickness values T and T shall be measured as described in 3.1.
c f
The thickness of the adhesive shall be between 12,5 μm and 75 μm with a permissible
tolerance of ±20 %. Preferred thicknesses are 20 μm, 25 μm, 38 μm, 50 μm, and 75 μm.
4 Internal marking
Not applicable.
– 6 – 61249-3-4 © IEC:1999(E)
5 Designation
The following code shall be used to designate adhesive coated polyimide films according to
this specification:
Example:  PI-IEC-61249-3-4 - A - 25 - 50 - 0 - FV1
film material
specification no.
type of adhesive
(A = acrylic, E = epoxide,
P = polyester)
adhesive thickness on side 1 (mm)
film thickness (mm)
adhesive thickness on side 2 (mm)
Flammability rating (see table 4)
If there is no risk of confusion, the designation may be abbreviated to read (the same example
as above): PI-lEC-A-25-50-0-FV1.
6 Properties of adhesive coated polyimide films
6.1 A ppearance
The adhesive coated film shall be free from blisters and wrinkles. There shall be no
imperfections which will be detrimental to the material properties or to their intended use. The
film shall be uniform in colour and free from foreign inclusions. Colour degradation shall not
occur when the film is processed in accordance with the manufacturer's instructions.
The adhesive shall be protected by a polymeric release film or release paper which shall
adhere until lamination. For polyimide films with adhesive on both sides, one adhesive layer or
both shall be protected with such release materials.
The appearance of the adhesive coated film shall only be inspected with the release material
present in cases where the release material is transparent. Where foreign inclusions appear to
be imbedded in the adhesive and/or between the adhesive and the polyester film, the release
material shall be removed and the coated film shall be re-inspected.
6.2 Properties of adhesive coated polyimide films after curing
6.2.1 Preparation of laminated specimens
In order to determine the properties listed in 6.2.2 and 6.2.3, laminated specimens shall be
prepared as follows.
61249-3-4 © IEC:1999(E) – 7 –
6.2.1.1 Specimens from cover sheets
Test specimens shall comply with the requirements of IEC 61189-2 (see annex A). They shall
be cut from a set of samples prepared by laminating copper foil to the film material under test.
Laminating conditions should be agreed upon between purchaser and supplier, and should
comply with the material manufacturer's recommendations regarding pressure, temperature
and pressing duration. The copper foil, as used in the fabrication of copper-clad laminates,
shall have a thickness of 35 μm (305 g/m ) and shall be applied with the untreated (shiny) side
to the adhesive layer.
If any argument arises in relation to the laminating conditions, it is desirable to apply
the standard procedures and conditions in the relevant test method specification (see
IEC 61189-2) by agreement between purchaser and supplier.
NOTE – When the release or protective materials are peeled off from coverlay films with punched holes and/or slits
for further fabrication processes, careful attention should be paid in order to avoid deformation of the film due to any
excessive peeling force.
6.2.1.2 Specimens from bonding films
The required test specimens according to the relevant clauses of IEC 61189-2 shall be cut
from a set of samples prepared by laminating copper foils to both sides of the film material
under test as described in 6.2.1.1, except for peel strength and heat shock testing.
For peel strength and heat shock testing the samples shall be prepared by laminating a single-
sided copper-clad epoxide/glass laminate on one side of the adhesive coated bonding film, and
an unclad epoxide/glass laminate with a thickness not less than 0,5 mm on the other side, as
described in 6.2.1.1. Two sets of samples shall be prepared: one with the copper foil facing
side 1 of the bonding film, one with the copper foil facing side 2 of the bonding film.
6.2.2 Electrical properties
Tabl
...

IEC 61249-3-4
Edition 1.0 1999-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Materials for printed boards and other interconnecting structures –
Part 3-4: Sectional specification set for unreinforced base materials, clad and
unclad (intended for flexible printed boards) – Adhesive coated flexible
polyimide film
Matériaux pour circuits imprimés et autres structures d’interconnexion –
Partie 3-4: Collection de spécifications intermédiaires pour les matériaux de
base non renforcés, recouverts ou non (prévus pour les circuits imprimés
flexibles) – Film flexible polyimide à revêtement adhésif

Copyright © 1999 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
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IEC 61249-3-4
Edition 1.0 1999-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Materials for printed boards and other interconnecting structures –
Part 3-4: Sectional specification set for unreinforced base materials, clad and
unclad (intended for flexible printed boards) – Adhesive coated flexible
polyimide film
Matériaux pour circuits imprimés et autres structures d’interconnexion –
Partie 3-4: Collection de spécifications intermédiaires pour les matériaux de
base non renforcés, recouverts ou non (prévus pour les circuits imprimés
flexibles) – Film flexible polyimide à revêtement adhésif

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
N
CODE PRIX
ICS 31.180 ISBN 2-8318-5752-X
– 2 – 61249-3-4 © CEI:1999
SOMMAIRE
AVANT-PROPOS .4

1 Domaine d'application.6
2 Références normatives .6
3 Matériaux et composition .6
4 Marquage interne.8
5 Désignation.10
6 Propriétés des films polyimides à revêtement adhésif.10
7 Dimensions et tolérances.16
8 Emballage et marquage .16
9 Essais de réception .18

Annexe A (informative) Tableau de correspondance pour les références
des méthodes d'essai.20

Tableau 1 – Epaisseurs préférentielles et tolérances maximales autorisées.8
Tableau 2 – Propriétés électriques .12
Tableau 3 – Propriétés liées au collage de la feuille de cuivre.14
Tableau 4 – Inflammabilité .14
Tableau 5 – Stabilité dimensionnelle des couches protectrices .14
Tableau 6 – Flux de collage.16
Tableau 7 – Tolérances maximales pour la largeur du matériau
de film fourni en rouleaux .16

61249-3-4 © IEC:1999 – 3 –
CONTENTS
FOREWORD.5

1 Scope.7
2 Normative reference .7
3 Materials and construction .7
4 Internal marking.9
5 Designation.11
6 Properties of adhesive coated polyimide films .11
7 Dimensions and tolerances .17
8 Packaging and marking.17
9 Acceptance testing .19

Annex A (informative) Conversion table for test method reference numbers.21

Table 1 – Preferred thicknesses and maximum permitted tolerances .9
Table 2 – Electrical properties .13
Table 3 – Properties related to the copper foil bond .15
Table 4 – Flammability .15
Table 5 – Dimensional stability of coverlays.15
Table 6 – Adhesive flow .17
Table 7 – Maximum tolerances for the width of film material supplied in rolls .17

– 4 – 61249-3-4 © CEI:1999
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
MATÉRIAUX POUR CIRCUITS IMPRIMÉS ET
AUTRES STRUCTURES D'INTERCONNEXION –

Partie 3-4: Collection de spécifications intermédiaires
pour les matériaux de base non renforcés, recouverts ou non
(prévus pour les circuits imprimés flexibles) –
Film flexible polyimide à revêtement adhésif

AVANT-PROPOS
1) La CEI (Commission Électrotechnique Internationale) est une organisation mondiale de normalisation composée
de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI). La CEI a pour objet de
favoriser la coopération internationale pour toutes les questions de normalisation dans les domaines de
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Leur élaboration est confiée à des comités d'études, aux travaux desquels tout Comité national intéressé par le
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liaison avec la CEI, participent également aux travaux. La CEI collabore étroitement avec l'Organisation
Internationale de Normalisation (ISO), selon des conditions fixées par accord entre les deux organisations.
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façon transparente, dans toute la mesure possible, les Normes internationales de la CEI dans leurs normes
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l’objet de droits de propriété intellectuelle ou de droits analogues. La CEI ne saurait être tenue pour
responsable de ne pas avoir identifié de tels droits de propriété et de ne pas avoir signalé leur existence
La Norme internationale CEI 61249-3-4 a été établie par le comité d'études 52 de la CEI:
Circuits imprimés.
Cette version bilingue, publiée en 2001-05, correspond à la version anglaise.
Le texte anglais de cette norme est basé sur les documents 52/773/FDIS et 52/798/RVD.
Le rapport de vote 52/798/RVD donne toute information sur le vote ayant abouti à l'approbation
de cette norme.
La version française de cette norme n'a pas été soumise au vote.
Cette publication a été rédigée selon les Directives ISO/CEI, Partie 3.
L'annexe A est donnée uniquement à titre d'information.
Le comité a décidé que le contenu de cette publication ne sera pas modifié avant 2005. A cette
date, la publication sera
• reconduite;
• supprimée;
• remplacée par une édition révisée, ou
• amendée.
61249-3-4 © IEC:1999 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MATERIALS FOR PRINTED BOARDS AND
OTHER INTERCONNECTING STRUCTURES –

Part 3-4: Sectional specification set for unreinforced base materials,
clad and unclad (intended for flexible printed boards) –
Adhesive coated flexible polyimide film

FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardiz
...