IEC 60738-1-4:1998

Thermistors - Directly heated positive step-function temperature coefficient - Part 1-4: Blank detail specification - Sensing application - Assessment level EZ

General Information

• Status: Published
• Publication Date: 02-Dec-1998
• ICS: 31.040.30 - Thermistors
• Technical Committee: TC 40 - Capacitors and resistors for electronic equipment
• Current Stage: DELPUB - Deleted Publication
• Start Date: 13-Feb-2008
• Completion Date: 26-Oct-2025

Relations

• Revised: IEC 60738-1-4:2008 - Thermistors - Directly heated positive step-function temperature coefficient - Part 1-4: Blank detail specification - Sensing application - Assessment level EZ
• Effective Date: 05-Sep-2023

Overview

IEC 60738-1-4:1998 is an international standard published by the International Electrotechnical Commission (IEC) focused on thermistors with a directly heated positive step-function temperature coefficient. This standard provides a blank detail specification specifically tailored for sensing applications, classified under assessment level EZ. This core document outlines the framework for manufacturers to create detailed specifications that align with IEC requirements, ensuring consistency, reliability, and quality in thermistor components used in temperature sensing.

Thermistors defined by this standard are specialized ceramic components whose electrical resistance increases sharply at a certain temperature threshold - a feature critical for various sensing and protection mechanisms. The blank detail specification serves as a template, helping standardize technical data presentation, testing procedures, and quality assurance measures.

Key Topics

• Thermistor Type and Identification
  The standard defines parameters to describe thermistor characteristics including construction type, outline dimensions, and typical applications. It emphasizes identification with short descriptions, reference drawings, and application groups according to the assessment level EZ.

• Mechanical and Electrical Specifications
  Detailed aspects such as mounting methods, dimensions (in millimetres or inches), coating material and properties, terminations, and flammability data are specified. Electrical parameters include zero-power resistance, maximum operating voltage, insulation resistance for insulated thermistors, and response times.

• Testing and Inspection Procedures
  IEC 60738-1-4 mandates quality conformance testing with tables outlining lot-by-lot and periodic inspection schedules. These include visual inspections, solderability and heat resistance tests, vibration, bump and shock resistance, temperature cycling, and endurance testing at various temperatures. Sampling plans and acceptance criteria ensure reliability and traceability in production.

• Marking and Ordering Information
  Requirements for product and packaging marking follow IEC 60738-1 guidelines to ensure clear identification. The specification outlines minimum ordering information details such as style reference, maximum voltage rating, and specification issue number.

• Coating and Packaging Details
  The coating's insulating or non-insulating nature, material type, and color are to be clearly documented. Packaging instructions cover bulk or tape packing, dimensions of packaging units, and disposal methods for packaging waste.

Applications

IEC 60738-1-4:1998 thermistors are primarily used in temperature sensing applications where a positive step-function behavior is critical. Common practical applications include:

• Thermal Protection
  Devices that require fast and reliable detection of temperature thresholds to prevent overheating and fire hazards.

• Temperature Monitoring and Control
  Incorporated into automated systems for monitoring temperature changes precisely, enabling control circuits to maintain optimal operating conditions.

• Electronic Component Safety
  Used in power electronics and capacitor circuits for temperature-triggered interruption or regulation.

• Industrial and Consumer Electronics
  Applied in appliances, heating systems, and various electronic instruments requiring dependable thermal sensing performance.

The standard’s emphasis on detailed electrical and mechanical parameters ensures thermistors certified under it meet rigorous requirements for sensitive and accurate temperature detection.

Related Standards

• IEC 60738-1:1998 – Generic specification for directly heated positive step-function temperature coefficient thermistors, establishing overall requirements that the detail specifications supplement.

• IEC 60050 – International Electrotechnical Vocabulary providing standardized terminology related to thermistors and electronic components.

• IEC 60027, IEC 60417, IEC 60617 – Standards covering letter symbols, graphical symbols for equipment and diagrams, used for consistent representation in technical documentation.

• IEC 60068 – Environmental testing standards referenced for assessing thermistor resistances, solderability, and mechanical robustness.

By adhering to IEC 60738-1-4, manufacturers and users ensure thermistor components meet internationally recognized benchmarks for quality, interchangeability, and performance in critical sensing applications.

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Keywords: IEC 60738-1-4, thermistors, positive step-function temperature coefficient, sensing applications, thermistor specifications, thermistor testing, temperature sensing components, electronic standards, IEC thermistor standard, thermistor quality assessment, temperature sensor reliability.

Standards Content (Sample)

INTERNATIONAL
IEC
STANDARD
60738-1-4
QC 440004
First edition
1998-12
Thermistors –
Directly heated positive step-function
temperature coefficient –
Part 1-4:
Blank detail specification –
Sensing application –
Assessment level EZ
Thermistances à basculement à coefficient de température
positif à chauffage direct –
Partie 1-4:
Spécification particulière cadre –
Application pour la mesure de température –
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 Electro-
technical 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
60738-1-4
QC 440004
First edition
1998-12
Thermistors –
Directly heated positive step-function
temperature coefficient –
Part 1-4:
Blank detail specification –
Sensing application –
Assessment level EZ
Thermistances à basculement à coefficient de température
positif à chauffage direct –
Partie 1-4:
Spécification particulière cadre –
Application pour la mesure de température –
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: [phone] e-mail: [e-mail] IEC web site http://www.iec.ch
Commission Electrotechnique Internationale
PRICE CODE
L
International Electrotechnical Commission
For price, see current catalogue

– 2 – 60738-1-4 © IEC:1998(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION

TEMPERATURE COEFFICIENT –
Part 1-4: Blank detail specification –

Sensing 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 60738-1-4 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.

The text of this standard is based on the following documents:
FDIS Report on voting
40/1084/FDIS 40/1100/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).

60738-1-4 © IEC:1998(E) – 3 –
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION

TEMPERATURE COEFFICIENT –
Part 1-4: Blank detail specification –

Sensing 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 – 60738-1-4 © IEC:1998(E)
[1] IEC 60738-1-4-XXX [2]
QC 440004
ELECTRONIC COMPONENTS OF ASSESSED IEC 60738-1-4 [4]

QUALITY IN ACCORDANCE WITH: QC 440004
[3] DIRECTLY HEATED POSITIVE
STEP-FUNCTION TEMPERATURE
COEFFICIENT THERMISTORS [5]
Outline drawing: [see 1.2] FOR SENSING APPLICATION
[. angle projection]
MODIFIED FERRO-ELECTRIC [6]
[7] CERAMIC MATERIAL
[Other shapes are permitted within the dimensions
given]
Assessment level: EZ [8]
[9]
Information on the availability of components
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;

60738-1-4 © IEC:1998(E) – 5 –
b) the material;
c) the colour, if applicable.
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
parameters. 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
Resistance R at T (if applicable);
NF NF
Isolation voltage (insulated thermistors only);

Insulation r
...