SIST EN IEC 60738-1:2023

Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification (IEC 60738-1:2022)

This part of IEC 60738 describes terms and methods of test for positive step-function temperature coefficient thermistors, insulated and non-insulated types typically made from ferro-electric semi-conductor materials.
It establishes standard terms, inspection procedures and methods of test for use in detail specifications for Qualification Approval and for Quality Assessment Systems for electronic components.

Direkt geheizte temperaturabhängige Widerstände mit positivem Temperaturkoeffizienten – Teil 1: Fachgrundspezifikation (IEC 60738-1:2022)

Thermistances - Coefficient de température positif à chauffage direct - Partie 1: Spécification générique (IEC 60738-1:2022)

L’IEC 60738-1:2022 décrit des termes et des méthodes d’essai pour les thermistances à basculement à coefficient de température positif, de type isolées ou non isolées, normalement fabriquées à partir de matériaux semiconducteurs ferroélectriques.
Elle établit des termes normaux, des procédures de contrôle et des méthodes d’essai destinés aux spécifications particulières pour l’homologation et pour les systèmes d’assurance de la qualité des composants électroniques.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
a) restructuration complète pour être conforme aux Directives ISO/IEC; catégorisation et réorganisation des méthodes d’essai dans ces catégories,
b) révision de certaines formulations, figures et références.

Termistorji - Neposredno ogrevani s pozitivnim temperaturnim koeficientom - 1. del: Splošna specifikacija (IEC 60738-1:2022)

Ta del standarda IEC 60738 opisuje pogoje in preskusne metode za termistorje s stopenjskim pozitivnim temperaturnim koeficientom, z izolacijo ali brez nje, ki so običajno izdelani iz feroelektričnih polprevodniških materialov.
Določa splošne pogoje, inšpekcijske postopke in preskusne metode za uporabo v podrobnih specifikacijah za odobritev kvalifikacije ter sisteme za ocenjevanje kakovosti elektronskih komponent.

General Information

• Status: Published
• Public Enquiry End Date: 27-Jan-2022
• Publication Date: 04-Dec-2022
• ICS: 31.040.30 - Thermistors
• Technical Committee: I11 - Imaginarni 11
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 30-Nov-2022
• Due Date: 04-Feb-2023
• Completion Date: 05-Dec-2022
• Ref Project: EN IEC 60738-1:2022 - Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification

Relations

• Revised: SIST EN 60738-1:2007/A1:2010 - Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification (IEC 60738-1:2006/A1:2009)
• Effective Date: 13-Apr-2021
• Replaces: SIST EN 60738-1:2007 - Thermistors - Directly heated positive temperature coefficient -- Part 1: Generic specification
• Effective Date: 29-Nov-2022
• Replaces: SIST EN 60738-1:2007/A1:2010 - Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification (IEC 60738-1:2006/A1:2009)
• Effective Date: 29-Nov-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 60738-1:2023
01-januar-2023
Nadomešča:
SIST EN 60738-1:2007
SIST EN 60738-1:2007/A1:2010
Termistorji - Neposredno ogrevani s pozitivnim temperaturnim koeficientom - 1.
del: Splošna specifikacija (IEC 60738-1:2022)
Thermistors - Directly heated positive temperature coefficient - Part 1: Generic
specification (IEC 60738-1:2022)
Direkt geheizte temperaturabhängige Widerstände mit positivem Temperaturkoeffizienten
– Teil 1: Fachgrundspezifikation (IEC 60738-1:2022)
Thermistances - Coefficient de température positif à chauffage direct - Partie 1:
Spécification générique (IEC 60738-1:2022)
Ta slovenski standard je istoveten z: EN IEC 60738-1:2022
ICS:
31.040.30 Termistorji Thermistors
SIST EN IEC 60738-1:2023 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 60738-1:2023

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SIST EN IEC 60738-1:2023


EUROPEAN STANDARD EN IEC 60738-1

NORME EUROPÉENNE

EUROPÄISCHE NORM November 2022
ICS 31.040.30 Supersedes EN 60738-1:2006; EN 60738-1:2006/A1:2009
English Version
Thermistors - Directly heated positive temperature coefficient -
Part 1: Generic specification
(IEC 60738-1:2022)
Thermistances - Coefficient de température positif à Direkt geheizte temperaturabhängige Widerstände mit
chauffage direct - Partie 1: Spécification générique positivem Temperaturkoeffizienten - Teil 1:
(IEC 60738-1:2022) Fachgrundspezifikation
(IEC 60738-1:2022)
This European Standard was approved by CENELEC on 2022-11-18. 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
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 60738-1:2022 E

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SIST EN IEC 60738-1:2023
EN IEC 60738-1:2022 (E)
European foreword
The text of document 40/2969/FDIS, future edition 4 of IEC 60738-1, prepared by IEC/TC 40
"Capacitors and resistors for electronic equipment" was submitted to the IEC-CENELEC parallel vote
and approved by CENELEC as EN IEC 60738-1:2022.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-08-18
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2025-11-18
document have to be withdrawn
This document supersedes EN 60738-1:2006 and all of its amendments and corrigenda (if any).
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 60738-1:2022 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60068-2-45:1980 NOTE Harmonized as EN 60068-2-45:1992 (not modified)
2

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SIST EN IEC 60738-1:2023
EN IEC 60738-1:2022 (E)
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.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60027 series Letters symbols to be used in electrical - series
technology
IEC 60050 series International Electrotechnical Vocabulary - -
(IEV)
IEC 60062 - Marking codes for resistors and capacitors EN 60062 -
IEC 60068-1 2013 Environmental testing - Part 1: General and EN 60068-1 2014
guidance
IEC 60068-2-1 2007 Environmental testing - Part 2-1: Tests - EN 60068-2-1 2007
Test A: Cold
IEC 60068-2-2 2007 Environmental testing - Part 2-2: Tests - EN 60068-2-2 2007
Test B: Dry heat
IEC 60068-2-6 - Environmental testing - Part 2-6: Tests - EN 60068-2-6 -
Test Fc: Vibration (sinusoidal)
IEC 60068-2-11 - Environmental testing - Part 2-11: Tests - EN IEC 60068-2-11 -
Test Ka: Salt mist
IEC 60068-2-13 - Environmental testing - Part 2-13: Tests - EN IEC 60068-2-13 -
Test M: Low air pressure
IEC 60068-2-14 - Environmental testing - Part 2-14: Tests - EN 60068-2-14 -
Test N: Change of temperature
IEC 60068-2-20 - Environmental testing - Part 2-20: Tests - EN IEC 60068-2-20 -
Test Ta and Tb: Test methods for
solderability and resistance to soldering
heat of devices with leads
IEC 60068-2-21 - Environmental testing - Part 2-21: Tests - EN IEC 60068-2-21 -
Test U: Robustness of terminations and
integral mounting devices
IEC 60068-2-27 - Environmental testing - Part 2-27: Tests - EN 60068-2-27 -
Test Ea and guidance: Shock
IEC 60068-2-30 - Environmental testing - Part 2-30: Tests - EN 60068-2-30 -
Test Db: Damp heat, cyclic (12 h + 12 h
cycle)
3

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SIST EN IEC 60738-1:2023
EN IEC 60738-1:2022 (E)
Publication Year Title EN/HD Year
IEC 60068-2-58 - Environmental testing - Part 2-58: Tests - EN 60068-2-58 -
Test Td: Test methods for solderability,
resistance to dissolution of metallization
and to soldering heat of surface mounting
devices (SMD)
IEC 60068-2-78 - Environmental testing - Part 2-78: Tests - EN 60068-2-78 -
Test Cab: Damp heat, steady state
IEC 60294 - Measurement of the dimensions of a EN 60294 -
cylindrical component with axial
terminations
IEC 60617 - Standard data element types with - -
associated classification scheme for
electric components - Part 4: IEC reference
collection fo standard data element types
and component classes
IEC 60717 - Method for the determination of the space EN 60717 -
required by capacitors and resistors with
unidirectional terminations
IEC 61193-2 - Quality assessment systems - Part 2: EN 61193-2 -
Selection and use of sampling plans for
inspection of electronic components and
packages
IEC 61249-2-7 - Materials for printed boards and other EN 61249-2-7 -
interconnecting structures - Part 2-7:
Reinforced base materials clad and unclad
- Epoxide woven E-glass laminated sheet
of defined flammability (vertical burning
test), copper-clad
IEC 61760-1 - Surface mounting technology - Part 1: EN IEC 61760-1 -
Standard method for the specification of
surface mounting components (SMDs)
ISO 80000-1 - Quantities and units - Part 1: General EN ISO 80000-1 -

4

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SIST EN IEC 60738-1:2023




IEC 60738-1

®


Edition 4.0 2022-10




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE
colour

inside










Thermistors – Directly heated positive temperature coefficient –

Part 1: Generic specification



Thermistances – Coefficient de température positif à chauffage direct –

Partie 1: Spécification générique
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 31.040.30 ISBN 978-2-8322-5731-9




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 60738-1:2023
– 2 – IEC 60738-1:2022 © IEC 2022
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 General requirements . 19
4.1 Units and symbols. 19
4.2 Preferred values . 20
4.2.1 Climatic categories . 20
4.2.2 Spacings . 20
4.3 Marking . 20
4.3.1 General . 20
4.3.2 Coding . 21
5 General provisions for measurements and test method . 21
5.1 General . 21
5.2 Standard conditions for testing . 21
5.2.1 Standard atmospheric conditions for testing . 21
5.2.2 Error of measurement . 21
5.3 Drying and recovery . 21
5.3.1 Drying . 21
5.3.2 Recovery . 22
5.3.3 Shock test severities . 22
5.3.4 Vibration severities . 22
5.4 Mounting (for surface mount thermistors only) . 22
5.4.1 General . 22
5.4.2 Printed wiring board and land pattern . 23
5.4.3 Wave soldering method . 23
5.4.4 Reflow soldering method . 23
6 Electrical tests and measurements . 24
6.1 Zero-power resistance . 24
6.1.1 General . 24
6.1.2 Measurement procedures . 24
6.1.3 Requirements . 25
6.2 Temperature coefficient of resistance . 25
6.2.1 General . 25
6.2.2 Requirements . 25
6.3 Insulation resistance (for insulated types only) . 25
6.3.1 General . 25
6.3.2 Test methods . 25
6.3.3 Applied voltage . 26
6.3.4 Requirements . 26
6.4 Voltage proof (for insulated types only) . 26
6.4.1 General . 26
6.4.2 Test methods . 26
6.4.3 Test voltage . 26
6.4.4 Requirements . 26
6.5 Resistance/temperature characteristic . 26

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SIST EN IEC 60738-1:2023
IEC 60738-1:2022 © IEC 2022 – 3 –
6.5.1 Test methods . 26
6.5.2 Requirements . 27
6.6 Dissipation factor at U (δ) . 27
max
6.6.1 General . 27
6.6.2 Preconditioning . 27
6.6.3 Test circuit . 27
6.6.4 Test methods . 27
6.6.5 Requirements . 28
6.7 Response time by ambient temperature change (t ) . 28
a
6.7.1 General . 28
6.7.2 Preconditioning . 28
6.7.3 Test procedures . 28
6.7.4 Measurement procedures . 29
6.7.5 Requirements . 29
6.8 Response time by power change (t ) . 29
p
6.8.1 Mounting . 29
6.8.2 Test methods . 29
6.9 Thermal time constant by ambient temperature change (τ ) . 30
a
6.10 Thermal time constant by cooling (τ ) . 30
c
6.10.1 Mounting . 30
6.10.2 Test methods . 30
6.10.3 Requirements . 32
6.11 Tripping current and tripping time. 32
6.12 Non-tripping current . 32
6.13 Residual current. 32
6.14 Surface temperature . 33
6.15 Inrush current . 34
6.15.1 Measuring circuit . 34
6.15.2 Measuring method . 34
6.16 Energy by discharge . 35
6.16.1 Measuring circuit . 35
6.16.2 Measuring method . 35
7 Mechanical test and measurements . 36
7.1 Visual examination and check of dimensions . 36
7.1.1 Visual examination . 36
7.1.2 Marking . 36
7.1.3 Dimensions (gauging) . 36
7.1.4 Dimensions (detail) . 36
7.2 Robustness of terminations . 36
7.2.1 General . 36
7.2.2 Test Ua – Tensile . 36
1
7.2.3 Test Ub – Bending . 37
7.2.4 Test Uc – Torsion . 37
7.2.5 Visual examination . 37
7.2.6 Final measurements and requirements . 37
7.3 Vibration . 37
7.4 Shock . 38
7.5 Shear (adhesion) test . 38

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SIST EN IEC 60738-1:2023
– 4 – IEC 60738-1:2022 © IEC 2022
7.5.1 Test conditions . 38
7.5.2 Test methods . 38
7.5.3 Requirements . 38
7.6 Substrate bending test . 38
7.6.1 Mounting . 38
7.6.2 Initial measurements . 39
7.6.3 Test procedures . 39
7.6.4 Measurements . 39
7.6.5 Requirements . 39
7.6.6 Final inspection and requirements . 39
8 Environmental and climatic tests . 39
8.1 Rapid change of temperature . 39
8.2 Climatic sequence. 39
8.2.1 General . 39
8.2.2 Initial measurements . 39
8.2.3 Dry heat . 40
8.2.4 Damp heat (cyclic), first cycle . 40
8.2.5 Cold. 40
8.2.6 Low air pressure . 40
8.2.7 Damp heat (cyclic), remaining cycles . 40
8.2.8 Final measurements . 40
8.3 Damp heat, steady state . 41
8.4 Endurance . 41
8.4.1 Endurance at room temperature (cycling) . 41
8.4.2 Endurance at upper category temperature . 42
8.4.3 Endurance at maximum operating temperature and maximum voltage . 43
8.4.4 Cold environment electrical cycling . 44
8.4.5 Thermal runaway . 45
9 Test related to component assembly . 45
9.1 Solderability . 45
9.1.1 General . 45
9.1.2 Thermistors with leads . 45
9.1.3 Surface mount thermistors . 46
9.2 Resistance to soldering heat . 46
9.2.1 General . 46
9.2.2 Test conditions . 46
9.2.3 The period of recovery . 47
9.2.4 Requirements for except surface mount thermistors . 47
9.2.5 Requirements for surface mount thermistors . 47
10 Quality assessment procedures . 47
Annex A (informative) Mounting for electrical measurements . 48
A.1 Mounting for thermistors without wire terminations . 48
A.2 Mounting for thermistors with wire terminations . 48
A.3 Mounting for surface mount thermistors . 49
Annex B (informative) Mounting for temperature measurements . 51
Annex Q (normative) Quality assessment procedures . 52
Q.1 General . 52
Q.2 Applicability of qualification approval . 52

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SIST EN IEC 60738-1:2023
IEC 60738-1:2022 © IEC 2022 – 5 –
Q.3 Primary stage of manufacture . 52
Q.4 Subcontracting . 52
Q.5 Structurally similar components . 52
Q.5.1 General . 52
Q.5.2 For electrical tests . 53
Q.5.3 For environmental tests . 53
Q.5.4 For visual inspection . 53
Q.5.5 For endurance tests . 53
Q.6 Qualification approval procedures . 53
Q.6.1 Eligibility for qualification approval . 53
Q.6.2 Application for qualification approval . 53
Q.6.3 Test procedure for qualification approval . 53
Q.6.4 Qualification approval based on the fixed sample size procedure. 54
Q.6.5 Granting of qualification approval . 59
Q.6.6 Maintenance of qualification approval . 59
Q.6.7 Quality conformance inspection . 60
Q.7 Rework and repair. 61
Q.7.1 Rework . 61
Q.7.2 Repair . 61
Q.8 Release for delivery . 61
Q.8.1 General . 61
Q.8.2 Release for delivery under qualification approval before the completion
of group B tests . 62
Q.9 Certified test records of released lots . 62
Q.10 Delayed delivery . 62
Q.11 Alternative test methods . 62
Q.12 Manufacture outside the geographical limits .
...

SLOVENSKI STANDARD
oSIST prEN IEC 60738-1:2022
01-januar-2022
Termistorji - Neposredno ogrevani s pozitivnim temperaturnim koeficientom - 1.
del: Splošna specifikacija
Thermistors - Directly heated positive temperature coefficient - Part 1: Generic
specification
Thermistances - Coefficient de température positif à chauffage direct - Partie 1:
Spécification générique
Ta slovenski standard je istoveten z: prEN IEC 60738-1:2021
ICS:
31.040.30 Termistorji Thermistors
oSIST prEN IEC 60738-1:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60738-1:2022

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oSIST prEN IEC 60738-1:2022

40/2880/CDV

COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60738-1 ED4
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2021-11-05 2022-01-28
SUPERSEDES DOCUMENTS:
40/2832/CD, 40/2864/CC

IEC TC 40 : CAPACITORS AND RESISTORS FOR ELECTRONIC EQUIPMENT
SECRETARIAT: SECRETARY:
Netherlands Mr Ronald Drenthen
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:


Other TC/SCs are requested to indicate their interest, if any,
in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

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.

TITLE:
Thermistors - Directly heated positive temperature coefficient - Part 1: Generic specification

PROPOSED STABILITY DATE: 2030

NOTE FROM TC/SC OFFICERS:


Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

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oSIST prEN IEC 60738-1:2022
60738-1/Ed4/CDV  IEC:2021 – 2 – 40/2880/CDV
1 CONTENTS
2
3 FOREWORD . 7
4 INTRODUCTION . 9
5 1 Scope . 10
6 2 Normative references . 10
7 3 Terms and definitions . 11
8 4 General requirements . 20
9 4.1 Units and symbols. 20
10 4.2 Preferred values . 20
11 4.2.1 Climatic categories . 20
12 4.2.2 Spacings . 20
13 4.3 Marking . 21
14 4.3.1 General . 21
15 4.3.2 Coding . 21
16 5 General provisions for measurements and test method . 21
17 5.1 General . 21
18 5.2 Standard conditions for testing . 21
19 5.2.1 Standard atmospheric conditions for testing . 21
20 5.2.2 Error of measurement . 22
21 5.3 Drying and recovery . 22
22 5.3.1 Drying . 22
23 5.3.2 Recovery . 22
24 5.3.3 Shock test severities. 22
25 5.3.4 Vibration severities . 22
26 5.4 Mounting (for surface mount thermistors only) . 23
27 5.4.1 General . 23
28 5.4.2 Printed wiring board and land pattern . 23
29 5.4.3 Wave soldering method . 23
30 5.4.4 Reflow soldering method . 23
31 6 Electrical tests and measurements . 24
32 6.1 Zero-power resistance . 24
33 6.1.1 General . 24
34 6.1.2 Measurement procedures . 24
35 6.1.3 Requirements . 24
36 6.2 Temperature coefficient of resistance . 25
37 6.2.1 General . 25
38 6.2.2 Requirements . 25
39 6.3 Insulation resistance (for insulated types only) . 25
40 6.3.1 General . 25
41 6.3.2 Test methods . 25
42 6.3.3 Applied voltage . 26
43 6.3.4 Requirements . 26
44 6.4 Voltage proof (for insulated types only) . 26
45 6.4.1 General . 26
46 6.4.2 Test methods . 26
47 6.4.3 Test voltage . 26
48 6.4.4 Requirements . 26

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oSIST prEN IEC 60738-1:2022
60738-1/Ed4/CDV  IEC:2021 – 3 – 40/2880/CDV
49 6.5 Resistance/temperature characteristic . 26
50 6.5.1 General . 26
51 6.5.2 Test methods . 26
52 6.5.3 Requirements . 26
53 6.6 Dissipation factor at U (δ) . 27
max
54 6.6.1 General . 27
55 6.6.2 Preconditioning . 27
56 6.6.3 Test circuit . 27
57 6.6.4 Test methods . 27
58 6.6.5 Requirements . 28
59 6.7 Response time by ambient temperature change (t ) . 28
a
60 6.7.1 General . 28
61 6.7.2 Preconditioning . 28
62 6.7.3 Test procedures. 28
63 6.7.4 Measurement procedures . 28
64 6.7.5 Requirements . 28
65 6.8 Response time by power change (t ) . 29
p
66 6.8.1 Mounting . 29
67 6.8.2 Test methods . 29
68 6.9 Thermal time constant by ambient temperature change (τ ) . 29
a
69 6.10 Thermal time constant by cooling (τ ) . 29
c
70 6.10.1 Mounting . 29
71 6.10.2 Test methods . 29
72 6.10.3 Requirements . 31
73 6.11 Tripping current and tripping time . 31
74 6.12 Non-tripping current . 31
75 6.13 Residual current . 32
76 6.14 Surface temperature . 32
77 6.15 Inrush current . 33
78 6.15.1 Measuring circuit . 33
79 6.15.2 Measuring method . 33
80 6.16 Energy by discharge . 34
81 6.16.1 Measuring circuit . 34
82 6.16.2 Measuring method . 34
83 7 Mechanical test and measurements . 34
84 7.1 Visual examination and check of dimensions . 34
85 7.1.1 Visual examination . 34
86 7.1.2 Marking . 34
87 7.1.3 Dimensions (gauging) . 35
88 7.1.4 Dimensions (detail) . 35
89 7.2 Robustness of terminations . 35
90 7.2.1 Test Ua – Tensile . 35
1
91 7.2.2 Test Ub – Bending (half of the samples) (not applicable to thermistors
92 encapsulated in glass or in envelopes) . 35
93 7.2.3 Test Uc – Torsion (remaining samples) . 35
94 7.2.4 Visual examination . 36
95 7.2.5 Final measurements and requirements . 36
96 7.3 Vibration . 36
97 7.4 Shock . 36
98 7.5 Shear (adhesion) test. 37

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99 7.5.1 Test conditions . 37
100 7.5.2 Test methods . 37
101 7.5.3 Requirements . 37
102 7.6 Substrate bending test . 37
103 7.6.1 Mounting . 37
104 7.6.2 Initial measurements . 37
105 7.6.3 Test procedures. 37
106 7.6.4 Measurements . 37
107 7.6.5 Requirements . 37
108 7.6.6 Final inspection and requirements . 37
109 8 Environmental and climatic tests . 37
110 8.1 Rapid change of temperature . 37
111 8.2 Climatic sequence. 38
112 8.2.1 Initial measurements . 38
113 8.2.2 Dry heat . 38
114 8.2.3 Damp heat (cyclic), first cycle . 38
115 8.2.4 Cold . 38
116 8.2.5 Low air pressure . 38
117 8.2.6 Damp heat (cyclic), remaining cycles . 38
118 8.2.7 Final measurements . 39
119 8.3 Damp heat, steady state . 39
120 8.4 Endurance . 39
121 8.4.1 Endurance at room temperature (cycling) . 39
122 8.4.2 Endurance at upper category temperature . 40
123 8.4.3 Endurance at maximum operating temperature and maximum voltage . 41
124 8.4.4 Cold environment electrical cycling . 42
125 8.4.5 Thermal runaway . 43
126 9 Test related to component assembly. 43
127 9.1 Solderability . 43
128 9.1.1 General . 43
129 9.1.2 Thermistors with leads . 43
130 9.1.3 Surface mount thermistors . 44
131 9.2 Resistance to soldering heat . 44
132 9.2.1 General . 44
133 10 Quality assessment procedures . 45
134 10.1 General . 45
135 10.1.1 Applicability of qualification approval . 45
136 10.2 Primary stage of manufacture . 46
137 10.3 Subcontracting . 46
138 10.4 Structurally similar components . 46
139 10.4.1 For electrical tests . 46
140 10.4.2 For environmental tests . 46
141 10.4.3 For visual inspection . 46
142 10.4.4 For endurance tests . 46
143 10.5 Qualification approval procedures . 46
144 10.5.1 Eligibility for qualification approval . 46
145 10.5.2 Application for qualification approval . 46
146 10.5.3 Test procedure for qualification approval . 47
147 10.5.4 Qualification approval based on the fixed sample size procedure. 47
148 10.5.5 Granting of qualification approval . 53

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149 10.5.6 Maintenance of qualification approval . 53
150 10.5.7 Quality conformance inspection . 53
151 10.6 Rework and repair. 54
152 10.6.1 Rework . 54
153 10.6.2 Repair . 54
154 10.7 Release for delivery . 54
155 10.7.1 General . 54
156 10.7.2 Release for delivery under qualification approval before the completion
157 of group B tests . 54
158 10.8 Certified test records of released lots . 55
159 10.9 Delayed delivery . 55
160 10.10 Alternative test methods . 55
161 10.11 Manufacture outside the geographical limits of IECQ NSIs . 55
162 10.12 Unchecked parameters . 55
163
164 Annex A (informative) Mounting for electrical measurements . 56
165 A.1 Mounting for thermistors without wire terminations . 56
166 A.2 Mounting for thermistors with wire terminations . 57
167 A.3 Mounting for surface mount thermistors . 57
168 Annex B (informative) Mounting for temperature measurements . 59
169 Annex X (informative)  Cross references to the prior revision of this standard . 60
170
171 Figure 1 – Typical resistance-temperature characteristic and definitions for PTC
172 thermistors (at zero power) . 13
173 Figure 2 – Typical R-TNF characteristic for PTC thermistors in sensor applications . 14
174 Figure 3 – Typical current/voltage characteristic for PTC thermistors . 14
175 Figure 4 – I against t at U . 17
in dc
176 Figure 5 – I against t at U . 18
in RMS
177 Figure 6 – Dissipation factor test circuit . 27
178 Figure 7 – Temperature gradient . 28
179 Figure 8 – Circuit for measurement of thermal time constant by cooling . 30
180 Figure 9 – Circuit for surface temperature measurement . 33
181 Figure 10 – Measuring circuit . 33
182 Figure 11 – Measuring circuit . 34
183 Figure 12 – Circuit for endurance at maximum operating temperature and maximum
184 voltage . 42
185 Figure A.1 – Example of a preferred mounting method for thermistors without wire
186 terminations . 56
187 Figure A.2 – Example of a preferred mounting method for thermistors with wire
188 terminations . 57
189 Figure A.3 – Example of a preferred mounting method for surface mount thermistors . 58
190 Figure B.1 – Example of a preferred mounting method for temperature measurement
191 on cylindrical heating elements . 59
192
193 Table 1 – Creepage distances and clearances . 20
194 Table 2 – Test severities of Vibration . 22
195 Table 3 – Tensile force . 35
196 Table 4 – Number of cycles per climatic category . 38

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197 Table 5 – Fixed sample size test schedule for qualification approval of thermistors for
198 current limitation – Assessment level EZ . 49
199 Table 6 – Fixed sample size test schedule for qualification approval of thermistors for
200 use as heating elements – Assessment level EZ . 50
201 Table 7 – Fixed sample size test schedule for qualification approval of thermistors for
202 inrush current application – Assessment level EZ . 51
203 Table 8 – Fixed sample size test schedule for qualification approval of thermistors for
204 use as temperature sensing elements – Assessment level EZ . 52
205 Table 9 – Quality conformance inspection for lot-by-lot inspection . 53
206 Table 10 – Quality conformance inspection for periodic testing . 54
207 Table A.1 – Recommendation land dimensions . 58
208 Table X.1 – Reference to IEC 60738-1 for clause/subclause or annex . 60
209
210

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211 INTERNATIONAL ELECTROTECHNICAL COMMISSION
212 ____________
213
214 THERMISTORS – DIRECTLY HEATED POSITIVE
215 TEMPERATURE COEFFICIENT –
216
217 Part 1: Generic specification
218
219
220 FOREWORD
221 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
222 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
223 international co-operation on all questions concerning standardization in the electrical and electronic fields. To
224 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
225 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
226 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
227 in the subject dealt with may participate in this preparatory work. International, governmental and non-
228 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
229 with the International Organization for Standardization (ISO) in accordance with conditions determined by
230 agreement between the two organizations.
231 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
232 consensus of opinion on the relevant subjects since each technical committee has representation from all
233 interested IEC National Committees.
234 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
235 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
236 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
237 misinterpretation by any end user.
238 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
239 tr
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