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

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 indetail specifictaions for Qualification Approval and for Quality Assessment Systems for electronic components.

Direkt geheizte temperaturabhängige Widerstände mit positivem Temperaturkoeffizienten -- Teil 1: Fachgrundspezifikation

Thermistances à coefficient de température positif à chauffage direct -- Partie 1: Spécification générique

L'IEC 60738-1:2006 décrit des termes et des méthodes d'essais pour les thermistances à basculement à coefficient de température positif, de type isolés ou non isolés, normalement fabriqués à partir de matériaux semiconducteurs ferroélectriques. Elle établit des termes normalisés, des procédures de contrôle et des méthodes d'essais destinés aux spécifications particulières pour l'homologation et pour les systèmes d'assurance de la qualité des composants électroniques. Cette troisième édition annule et remplace la deuxième édition parue en 1998 dont elle constitue une révision mineure. Les modifications par rapport à l'édition antérieure portent sur les tableaux, les figures et les références.

Termistorji - Neposredno ogrevani s pozitivnim temperaturnim koeficientom - 1. del: Rodovna specifikacija (IEC 60738-1:2006)

General Information

Status
Published
Publication Date
31-Dec-2006
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Jan-2007
Due Date
01-Jan-2007
Completion Date
01-Jan-2007

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---------------------- Page: 1 ----------------------
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
---------------------- Page: 2 ----------------------
EN 60738-1:2006 - 2 -
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.
__________
---------------------- Page: 3 ----------------------
- 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
Undated reference.
Valid edition at date of issue.
---------------------- Page: 4 ----------------------
EN 60738-1:2006 - 4 -
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
IEC 60294 - Measurement of the dimensions of a - -
cylindrical component having two axial
terminations
IEC 60410 - Sampling plans and procedures for inspection - -
by attributes
IEC 60617 data- Graphical symbols for diagrams - - -
base
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)
IEC QC 001002-3 - IEC Quality Assessment System for - -
Electronic Components (IECQ) - Rules of
Procedure - Part 3: Approval procedures
ISO 1000 - SI units and recommendations for the use of - -
their multiples and of certain other units
---------------------- Page: 5 ----------------------
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
Commission Electrotechnique Internationale XA
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 6 ----------------------
– 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

7.12 Response time by power change (t ).....................................................................34

7.13 Thermal time constant by ambient temperature change (τ ) ..................................35

7.14 Thermal time constant by cooling (τ )....................................................................35

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

---------------------- Page: 7 ----------------------
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..............................................................................................47

7.29 Inrush current........................................................................................................48

7.30 Mounting (for surface mount thermistors only) .......................................................49

7.31 Shear (adhesion) test ............................................................................................50

7.32 Substrate bending test ..........................................................................................50

Annex A (normative) Interpretation of sampling plans and procedures as described in

IEC 60410 for use within the IEC quality assessment system for electronic

components (IECQ) ..............................................................................................................51

Annex B (informative) Mounting for electrical measurements (except surface mount

types) ...................................................................................................................................52

Annex C (informative) Mounting for temperature measurements ..........................................55

Figure 1 – Typical resistance-temperature characteristic and definitions for PTC

thermistors (at zero power) ...................................................................................................10

Figure 2 – Typical R-TNF characteristic for PTC thermistors in sensor applications ..............11

Figure 3 – Typical current/voltage characteristic for PTC thermistors ....................................11

Figure 4 – I against t at U ................................................................................................14

in dc

Figure 5 – I against t at U ..............................................................................................15

in rms

Figure 6 – Dissipation factor test circuit ................................................................................33

Figure 7 – Temperature gradient...........................................................................................34

Figure 8 – Circuit for measurement of thermal time constant by cooling................................36

Figure 9 – Circuit for endurance at maximum operating temperature and maximum

voltage..................................................................................................................................45

Figure 10 – Circuit for surface temperature measurement.....................................................48

Figure 11 – Measuring circuit................................................................................................48

Figure B.1 – Example of a preferred mounting method for thermistors without wire

terminations..........................................................................................................................52

Figure B.2 – Example of a preferred mounting method for thermistors with wire

terminations..........................................................................................................................53

Figure B.3 – Example of a preferred mounting method for surface mount thermistors ...........54

Figure C.1 – Example of a preferred mounting method for temperature measurement

on cylindrical heating elements .............................................................................................55

Table 1 – Creepage distances and clearances ......................................................................18

Table 2 – Fixed sample size test schedule for qualification approval of thermistors for

current limitation – Assessment level EZ...............................................................................22

Table 3 – Fixed sample size test schedule for qualification approval of thermistors for

use as heating elements – Assessment level EZ...................................................................23

Table 4 – Fixed sample size test schedule for qualification approval of thermistors for

inrush current application – Assessment level EZ .................................................................24

Table 5 – Fixed sample size test schedule for qualification approval of thermistors for

use as temperature sensing elements, Assessment level EZ ................................................25

---------------------- Page: 8 ----------------------
– 4 – 60738-1  IEC:2006(E)

Table 6 – Quality conformance inspection for lot-by-lot inspection ........................................26

Table 7 – Quality conformance inspection for periodic testing ...............................................27

Table 8 – Tensile force .........................................................................................................37

Table 9 – Number of cycles per climatic category .................................................................42

---------------------- Page: 9 ----------------------
60738-1  IEC:2006(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
THERMISTORS – DIRECTLY HEATED POSITIVE
TEMPERATURE COEFFICIENT –
Part 1: Generic specification
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

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). 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. 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 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 IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

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 60738-1 has been prepared by IEC technical committee 40:

Capacitors and resistors for electronic equipment.

This third edition cancels and replaces the second edition published in 1998 and constitutes a

minor revision. The changes with respect to the previous edition refer to the tables, figures

and references.
The text of this standard is based on the following documents:
FDIS Report on voting
40/1651/FDIS 40/1730/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.
---------------------- Page: 10 ----------------------
– 6 – 60738-1  IEC:2006(E)

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The QC number that appears on the front cover of this publication is the specification number

in the IEC Quality Assessment System for Electronic Components (IECQ).

IEC 60738 consists of the following parts, under the general title Thermistors – Directly

heated positive step-function coefficient:
Part 1: Generic specification

Part 1-1: Blank detail specification – Current limiting application – Assessment level EZ

Part 1-2: Blank detail specification – Heating element application – Assessment level EZ

Part 1-3: Blank detail specification – Inrush current application – Assessment level EZ

Part 1-4: Blank detail specification – Sensing application – Assessment level EZ

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 standard may be issued at a later date.
---------------------- Page: 11 ----------------------
60738-1  IEC:2006(E) – 7 –
THERMISTORS – DIRECTLY HEATED POSITIVE
TEMPERATURE COEFFICIENT –
Part 1: Generic specification
1 Scope

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.
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 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050 (all parts), International Electrotechnical Vocabulary (IEV)
IEC 60062, Marking codes for resistors and capacitors
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
Amendment 1 (1992)
IEC 60068-2-1:1990, Environmental testing – Part 2: Tests – Tests A: Cold
Amendment 1 (1993)
Amendment 2 (1994)
IEC 60068-2-2:1974, Environmental testing – Part 2: Tests – Tests B: Dry heat
Amendment 1 (1993)

IEC 60068-2-6, Environmental testing – Part 2: Tests – Test Fc: Vibration (sinusoidal)

IEC 60068-2-11, Environmental testing – Part 2: Tests – Test Ka: Salt mist
IEC 60068-2-13, Environmental testing – Part 2: Tests – Test M: Low air pressure

IEC 60068-2-14:1984, Environmental testing – Part 2: Tests – Test N: Change of temperature

Amendment 1 (1986)
IEC 60068-2-20:1979, Environmental testing – Part 2: Tests – Test T: Soldering
Amendment 2 (1987)
IEC 60068-2-21, Environmental testing – Part 2-21: Tests – Test U: Robustness of
terminations and integral mounting devices
---------------------- Page: 12 ----------------------
– 8 – 60738-1  IEC:2006(E)

IEC 60068-2-27, Environmental testing – Part 2: Tests – Test Ea and guidance: Shock

IEC 60068-2-29, Environmental testing – Part 2: Tests – Test Eb and guidance: Bump

IEC 60068-2-30:2005, Environmental testing – Part 2: Tests – Test Db: Damp heat, cyclic

(12 h + 12-hour cycle)

IEC 60068-2-45:1980, Environmental testing – Part 2: Tests – Test XA and guidance –

Immersion in cleaning solvents

IEC 60068-2-58, Environmental testing – Part 2-58: Tests – 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 – Test Cab: Damp heat, steady

state

IEC 60294, Measurement of the dimensions of a cylindrical component having two axial

terminations
IEC 60410, Sampling plans and procedures for inspection by attributes
IEC 60617 (all parts) [DB] : Graphical symbols for diagrams

IEC 60717, Method for determination of the space required by capacitors and resistors with

unidirectional terminations

IEC 61249-2-7, Materials for printed boards and other 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: Standard method for the specification of

surface mounting components (SMDs)

IEC QC 001002-3, Rules of Procedure of the IEC Quality Assessment System for Electronic

Components (IECQ) – Part 3: Approval procedures

ISO 1000, SI units and recommendations for the use of their multiples and of certain other

units
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
type

group of components having similar design features and the similarity of whose manufacturing

techniques enables them to be grouped together either for qualification approval or for quality

conformance inspection
They are generally covered by a single detail specification

NOTE Components described in several detail specifications, may, in some cases, be considered as belonging to

the same type but they are generally covered by a single detail specification.
—————————
“DB” refers to the IEC on-line database.
---------------------- Page: 13 ----------------------
60738-1  IEC:2006(E) – 9 –
3.2
style
variation within a type having specific nominal dimensions and characteristics
3.3
thermistor

thermally sensitive semiconducting resistor which exhibits a significant change in electrical

resistance with a change in body temperature
3.4
positive temperature coefficient thermistor
thermistor, the resistance of which inc
...

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