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EUROPEAN STANDARD
EN 60738-1
NORME EUROPÉENNE
June 2006
EUROPÄISCHE NORM
ICS 31.040.30
English version
Thermistors -
Directly heated positive temperature coefficient
Part 1: Generic specification
(IEC 60738-1:2006)
Thermistances à coefficient  Direkt geheizte temperaturabhängige
de température positif Widerstände mit positivem
à chauffage direct Temperaturkoeffizienten
Partie 1: Spécification générique Teil 1: Fachgrundspezifikation
(CEI 60738-1:2006) (IEC 60738-1:2006)

This European Standard was approved by CENELEC on 2006-05-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60738-1:2006 E
Foreword
The text of document 40/1651/FDIS, future edition 3 of IEC 60738-1, prepared by IEC TC 40, Capacitors
and resistors for electronic equipment, was submitted to the IEC-CENELEC parallel vote and was
approved by CENELEC as EN 60738-1 on 2006-05-01.
This European Standard supersedes EN 60738-1:1999.
The changes with respect to EN 60738-1:1999 refer to the tables, figures and references.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2007-02-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-05-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60738-1:2006 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 60738-1:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60027 Series Letter symbols to be used in electrical HD 60027 Series
technology
IEC 60050 Series International Electrotechnical Vocabulary - -
(IEV)
IEC 60062 (mod) 2004 Marking codes for resistors and capacitors EN 60062 2005

IEC 60068-1 1988 Environmental testing -
+ corr. October 1988 Part 1: General and guidance
+ A1 1992 EN 60068-1 1994
IEC 60068-2-1 1990 Environmental testing - EN 60068-2-1 1993
+ A1 1993 Part 2: Tests - Tests A: Cold + A1 1993
+ A2 1994 + A2 1994
IEC 60068-2-2 1974 Basic environmental testing procedures - EN 60068-2-2 1993

+ A1 1993 Part 2: Tests - Tests B: Dry heat + A1 1993

1) 2)
IEC 60068-2-6 - Environmental testing - EN 60068-2-6 1995
Part 2: Tests - Test Fc: Vibration (sinusoidal)

1) 2)
IEC 60068-2-11 - Environmental testing - EN 60068-2-11 1999
Part 2: Tests - Test Ka: Salt mist

1) 2)
IEC 60068-2-13 - Environmental testing - EN 60068-2-13 1999
Part 2: Tests - Test M: Low air pressure

IEC 60068-2-14 1984 Environmental testing -
+ A1 1986 Part 2: Tests - Test N: Change of temperature EN 60068-2-14 1999

IEC 60068-2-20 1979 Basic environmental testing procedures -
+ A2 1987 Part 2: Tests - Test T: Soldering HD 323.2.20 S3 1988

1) 2)
IEC 60068-2-21 - Environmental testing - EN 60068-2-21 1999
Part 2-21: Tests - Test U: Robustness of
terminations and integral mounting devices

1) 2)
IEC 60068-2-27 - Basic environmental testing procedures - EN 60068-2-27 1993
Part 2: Tests - Test Ea and guidance: Shock

1) 2)
IEC 60068-2-29 - Basic environmental testing procedures - EN 60068-2-29 1993
Part 2: Tests - Test Eb and guidance: Bump

1)
Undated reference.
2)
Valid edition at date of issue.

Publication Year Title EN/HD Year
IEC 60068-2-30 2005 Environmental testing - EN 60068-2-30 2005
Part 2-30: Tests - Test Db: Damp heat, cyclic
(12 h + 12 h cycle)
IEC 60068-2-45 1980 Basic environmental testing procedures - EN 60068-2-45 1992
Part 2: Tests - Test Xa and guidance:
Immersion in cleaning solvents

1) 2)
IEC 60068-2-58 - Environmental testing - EN 60068-2-58 2004
Part 2-58: Tests - Test Td: Test methods for + corr. December 2004
solderability, resistance to dissolution of
metallization and to soldering heat of surface
mounting devices (SMD)
1) 2)
IEC 60068-2-78 - Environmental testing - EN 60068-2-78 2001
Part 2-78: Tests - Test Cab: Damp heat,
steady state
1)
IEC 60294 - Measurement of the dimensions of a - -
cylindrical component having two axial
terminations
1)
IEC 60410 - Sampling plans and procedures for inspection - -
by attributes
IEC 60617 data- Graphical symbols for diagrams - - -
base
1)
IEC 60717 - Method for the determination of the space - -
required by capacitors and resistors with
unidirectional terminations
1) 2)
IEC 61249-2-7 - Materials for printed boards and other EN 61249-2-7 2002
interconnecting structures - + corr. September 2005
Part 2-7: Reinforced base materials, clad and
unclad - Epoxide woven E-glass laminated
sheet of defined flammability (vertical burning
test), copper-clad
1) 2)
IEC 61760-1 - Surface mounting technology - EN 61760-1 2006
Part 1: Standard method for the specification
of surface mounting components (SMDs)

1)
IEC QC 001002-3 - IEC Quality Assessment System for - -
Electronic Components (IECQ) - Rules of
Procedure - Part 3: Approval procedures

1)
ISO 1000 - SI units and recommendations for the use of - -
their multiples and of certain other units

INTERNATIONAL IEC
STANDARD 60738-1
QC 440000
Third edition
2006-04
Thermistors – Directly heated positive
temperature coefficient –
Part 1:
Generic specification
 IEC 2006  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: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
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For price, see current catalogue

– 2 – 60738-1  IEC:2006(E)
CONTENTS
FOREWORD.5

1 Scope.7
2 Normative references .7
3 Terms and definitions .8
4 Units and symbols .16
5 Preferred values.17
5.1 Climatic categories.17
5.2 Marking .17
5.3 Spacings .18
6 Quality assessment procedures.18
6.1 General .18
6.2 Primary stage of manufacture.19
6.3 Subcontracting .19
6.4 Structurally similar components.19
6.5 Qualification approval procedures .20
6.6 Rework and repair .27
6.7 Release for delivery .27
6.8 Certified test records of released lots .28
6.9 Delayed delivery.28
6.10 Alternative test methods .28
6.11 Manufacture outside the geographical limits of IECQ NSIs .28
6.12 Unchecked parameters.28
7 Test and measurement procedures.28
7.1 General .28
7.2 Standard conditions for testing .29
7.3 Drying and recovery .29
7.4 Visual examination and check of dimensions.30
7.5 Zero-power resistance.30
7.6 Temperature coefficient of resistance.31
7.7 Insulation resistance (for insulated types only) .31
7.8 Voltage proof (for insulated types only) .32
7.9 Resistance/temperature characteristic.32
7.10 Dissipation factor at U (δ) .33
max
7.11 Response time by ambient temperature change (t ) .34
a
7.12 Response time by power change (t ).34
p
7.13 Thermal time constant by ambient temperature change (τ ) .35
a
7.14 Thermal time constant by cooling (τ ).35
c
7.15 Robustness of terminations .37
7.16 Solderability .38
7.17 Resistance to soldering heat .39
7.18 Rapid change of temperature .40
7.19 Vibration.40
7.20 Bump .40
7.21 Shock.41

60738-1  IEC:2006(E) – 3 –
7.22 Climatic sequence .41
7.23 Damp heat, steady state.42
7.24 Endurance.43
7.25 Tripping current and tripping time .46
7.26 Non-tripping current .47
7.27 Residual current .47
7.28 Surface temperature.
...