IEC 60738-1-1:1998

INTERNATIONAL
IEC
STANDARD
60738-1-1
QC 440001
Second edition
1998-12
Thermistors –
Directly heated positive step-function
temperature coefficient –
Part 1-1:
Blank detail specification –
Current limiting application – Assessment level EZ
Thermistances à basculement à coefficient de température
positif à chauffage direct –
Partie 1-1:
Spécification particulière cadre –
Application pour limitation de courant –
Niveau d’assurance EZ
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
60738-1-1
QC 440001
Second edition
1998-12
Thermistors –
Directly heated positive step-function
temperature coefficient –
Part 1-1:
Blank detail specification –
Current limiting application – Assessment level EZ
Thermistances à basculement à coefficient de température
positif à chauffage direct –
Partie 1-1:
Spécification particulière cadre –
Application pour limitation de courant –
Niveau d’assurance EZ
 IEC 1998  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: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
L
International Electrotechnical Commission
For price, see current catalogue

– 2 – 60738-1-1 © IEC:1998(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION

TEMPERATURE COEFFICIENT –
Part 1-1: Blank detail specification –

Current limiting application – Assessment level EZ
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 60738-1-1 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.

This second edition cancels and replaces the first edition published in 1982.
The text of this standard is based on the following documents:
FDIS Report on voting
40/1081/FDIS 40/1097/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.
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).

60738-1-1 © IEC:1998(E) – 3 –
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION

TEMPERATURE COEFFICIENT –
Part 1-1: Blank detail specification –

Current limiting application – Assessment level EZ

INTRODUCTION
Blank detail specification
A blank detail specification is a supplementary document to the generic specification and
contains requirements for style and layout and minimum content of detail specifications. Detail
specifications not complying with these requirements shall not be considered as being in
accordance with IEC specifications nor shall they so be described.
In the preparation of detail specifications the content of 1.4 of the generic specification shall be
taken into account.
The numbers between brackets on the first page correspond to the following information which
shall be inserted in the position indicated.
Identification of the detail specification
[1] The "International Electrotechnical Commission" or the National Standards Organization
under whose authority the detail specification is drafted.
[2] The IEC or National Standards number of the detail specification, date of issue and any
further information required by the national system.
[3] The number and issue number of the IEC or national generic specification.
[4] The IEC number of the blank detail specification.
Identification of the thermistor
[5] A short description of the type of thermistor.
[6] Information on typical construction (if applicable).
NOTE – When the thermistor is not designed for use on printed boards, this should clearly be stated in the detail
specification in this position.

[7] Outline drawing with main dimensions which are of importance for interchangeability
and/or reference to the national or international documents for outlines. Alternatively, this
drawing may be given in an annex to the detail specification.
[8] Application or group of applications covered and/or assessment level.
[9] Reference data on the most important properties, to allow comparison between the various
thermistor types.
– 4 – 60738-1-1 © IEC:1998(E)
[1] IEC 60738-1-1-XXX [2]
QC 440001XXXXXX
ELECTRONIC COMPONENTS OF ASSESSED IEC 60738-1-1 [4]

QUALITY IN ACCORDANCE WITH: QC 440001

[3] DIRECTLY HEATED POSITIVE
STEP-FUNCTION TEMPERATURE
COEFFICIENT THERMISTORS [5]
Outline drawing: [see 1.2] FOR CURRENT LIMITING
[. angle projection] APPLICATION
MODIFIED FERRO-ELECTRIC [6]
[7] CERAMIC MATERIAL
[Other shapes are permitted within the dimensions given]
Assessment level: EZ [8]
Information on the availability of components
[9]
qualified to this detail specification is given in
the Register of Approvals.
1 General data
1.1 Method(s) of mounting (to be inserted)
(See 4.12.1 of IEC 60738-1.)
1.2 Dimensions
(All dimensions are in millimetres or inches and millimetres; it shall be stated which dimensions
are suitable for gauging.)
Dimensioned drawing(s) shall be given in the detail specification. If necessary, the dimensions
may be listed in tabular form with reference to styles or codes.
1.3 Coating
The detail specification shall state:
a) whether the coating is insulating or non-insulating;
b) the material;
c) the colour, if applicable.
60738-1-1 © IEC:1998(E) – 5 –
1.4 Terminations
The detail specification shall state whether the terminations are suitable for soldering. If they are

not, suitable methods of connection shall be stated for example: welding, clamping or crimping.

1.5 Flammability
The detail specification shall state whether the thermistor is actively or passively flammable if

applicable. The test method shall be given in the test schedule.

1.6 Resistance to solvents
The detail specification shall state whether the coating and the marking of the thermistor are
solvent resistant if applicable. The test methods shall be given in the test schedule.
1.7 Packaging
The detail specification shall give the following information (if required):
a) whether bulk packed or taped and if taped, drawing or references;
b) the dimensions of the immediate packaging and the number of thermistors packed;
c) the dimensions of the outer package and the number of immediate packages;
d) methods of disposal of the packaging material.
1.8 Electrical data/Ratings and characteristics
The detail specification shall give units and tolerances or limiting values for the following para-
meters. If necessary, electrical data may be listed in tabular form, with reference to styles and codes.
Upper/Lower category temperatures (UCT/LCT);
Operating temperature range at maximum voltage;
Maximum voltage (U );
max.
Zero-power resistance (R );
T
Isolation voltage (insulated thermistors only);
Insulation resistance (insulated thermistors only);
Tripping current (I );
t
Maximum non-tripping current (I );
max. nt
Residual current at U (I );
max. res
Maximum overload current (I
);
mo
Switching temperature (T ) for information only.
b
1.9 Related documents
Generic specification
IEC 60738-1:1998, Thermistors – Directly heated positive step-function temperature coefficient –
Part 1: Generic specification
1.10 Marking
The marking of the thermistors and package containing the thermistors shall be in accordance
with the requirements of 2.4 of IEC 60738-1.
The details of the marking of the thermistors and package containing the thermistor shall be
given in full in the detail specification.

– 6 – 60738-1-1 © IEC:1998(E)
1.11 Ordering information
Orders for thermistors covered by this specification shall contain, in clear or in coded form, the

following minimum information:

a) style reference;
b) maximum continuous a.c. voltage;

c) number and issue reference of the detail specification.

1.12 Additional information (not for inspection purposes)

1.13 Additional or increased severities or requirements to those specified in the generic
sectional specification
NOTE – Additions or increased requirements should be specified only when essential.
2 Inspection requirements
2.1 Procedures
2.1.1 For qualification approval, the procedures shall be in accordance with the generic
specification, IEC 60738-1, 3.5.
2.1.2 For quality conformance inspection, the test schedules (tables 1 and 2) include sampling,
periodicity, severities and requirements. The formation of inspection lots is covered by 3.5.7 of
the generic specification.
The following list applies to the test schedules developed in tables 1 and 2:
1) Subclause numbers of tests and performance requirements refer to the generic specification,
IEC 60738-1, and clause 1 of this specification.
2) Number to be tested: sample size as directly allotted to the code letter for IL in table IIA of
IEC 60410 (single sampling plan for normal inspection).
3) In these tables: p is the periodicity (in months)
n is the sample size
c is the acceptance criterion (permitted number of non-conforming items)
D indicates a destructive test
ND indicates a non-destructive test
IL is the inspection level
4) The temperature at which the zero-power resistance shall be measured is the temperature
specified in the detail specification. This temperature shall be stated, where required, in the
test schedule.
5) The specimens used for this group may, at the discretion of the manufacturer, be used for
any subsequent group which is identified as being "destructive".
6) The soldering – solderability and soldering – resistance to heat tests shall only be applied
where the thermistor has terminations which are appropriate for soldering.
7) Where the terminations are stated to be suitable for printed wiring applications, the
appropriate test conditions in IEC 60068 shall apply.
8) The thermistors shall be mounted by their normal means.
9) The bump test and the shock test are alternatives. The test selected in the detail
specification shall be used.
60738-1-1 © IEC:1998(E) – 7 –
10) The detail specification shall specify which of the endurance tests in groups C4, C5 and
D1 respectively are appropriate to the construction and application of the thermistor.

11) Any deviation from annex B of the generic specification shall be given in the detail

specification.
12) 100 % testing shall be followed by re-inspection by sampling in order to monitor outgoing

quality level by non-conforming items per million (ppm). The sampling level shall be

–6
established by the manufacturer
...