IEC 60738-1-2:1998

Thermistors - Directly heated positive step-function temperature coefficient - Part 1-2: Blank detail specification - Heating element application - Assessmen level EZ

Supplementary document to the generic specification, contains requirements for style and layout and minimum content of detail specifications.

General Information

• Status: Published
• Publication Date: 09-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 60738-1-2:2008 - Thermistors - Directly heated positive step-function temperature coefficient - Part 1-2: Blank detail specification - Heating element application - Assessment level EZ
• Effective Date: 05-Sep-2023

Overview

IEC 60738-1-2:1998 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies requirements for directly heated positive step-function temperature coefficient (PTC) thermistors, focusing on heating element applications at assessment level EZ. This standard serves as a supplementary "blank detail specification" to the generic IEC 60738-1 standard, outlining detailed requirements for style, layout, and minimum content when drafting specific detail specifications for these thermistors.

The standard ensures uniformity and clarity in the specification of PTC thermistors used as heating elements, facilitating consistent quality assessment and application compatibility worldwide. It is particularly critical for manufacturers, testing laboratories, and users who require reliable performance and quality assurance for these specialized temperature-sensitive components.

Key Topics

• Scope and Purpose: IEC 60738-1-2 supplements the generic specification IEC 60738-1 by providing a template for creating detailed product specifications, focusing on key aspects such as style, layout, and the minimum essential content necessary for full compliance with IEC standards.

• Thermistor Identification: The standard stresses precise identification of the thermistor type, construction, outline drawings, application groups, and critical reference data. It mandates including information on aspects such as coating materials, terminations, flammability, solvent resistance, and marking.

• Technical and Electrical Characteristics: Detailed parameters such as upper and lower category temperatures, operating temperature ranges, maximum voltage, zero-power resistance, switching temperature, inrush current, residual current, and final surface temperature are specified with corresponding test methods.

• Inspection and Testing Procedures: The standard incorporates comprehensive quality conformance inspection and quantity conformance inspection schedules, covering visual examination, marking checks, solderability, resistance to heat, mechanical robustness, vibration, shock, climatic endurance, and electrical performance tests.

• Packaging and Ordering: Specifications on packaging methods (bulk or taped), dimensions, quantities, disposal methods, and specific ordering requirements ensure proper logistics and traceability.

• Quality Assurance: Assessment level EZ denotes a specific quality assurance level which governs the acceptance criteria and testing severity, ensuring that components comply with defined performance and reliability thresholds.

Applications

IEC 60738-1-2:1998 primarily applies to the design, qualification, production, and quality verification of directly heated PTC thermistors used as heating elements. These thermistors are commonly integrated into:

• Overcurrent protection devices in electrical equipment
• Heating elements in appliances such as coffee makers, hair dryers, and industrial heaters
• Thermal switches for temperature regulation and control systems
• Applications that require reliable, self-regulating heating components with positive temperature coefficients

Adherence to this standard ensures that heating element thermistors meet international quality and safety benchmarks, providing consistency in performance, durability, and interchangeability across manufacturers and regions.

Related Standards

• IEC 60738-1 (Generic Specification): The foundational document detailing general requirements for directly heated positive step-function temperature coefficient thermistors, serving as a baseline for detail specifications like IEC 60738-1-2.

• IEC 60050: International Electrotechnical Vocabulary (IEV): Defines standard terminology relevant to electrotechnical components and systems.

• IEC 60027, 60417, 60617: Standards covering graphical symbols and letter symbols used for marking and diagramming of electrical components, referenced for consistent labeling and identification in thermistor specifications.

• IEC 60068: Environmental testing standards that guide soldering and termination test conditions relevant for thermistors used in printed wiring applications.

• IEC Quality Assessment System for Electronic Components (IECQ): Related to the quality control and certification system under which IEC 60738-1-2 operates, especially noted by the QC 440002 specification number.

Summary

IEC 60738-1-2:1998 establishes a crucial framework for the detailed specification of directly heated PTC thermistors applied as heating elements, ensuring global standardization on technical, quality, and testing criteria. Utilizing this standard helps manufacturers and end-users achieve reliable performance, quality consistency, and international interoperability for thermistor-based heating applications.

Keywords: IEC 60738-1-2, PTC thermistor, heating element thermistor, positive temperature coefficient thermistor, thermistor specification, thermistor quality assurance, thermistor testing, IEC standards, electronic component standardization, thermistor application.

Standards Content (Sample)

INTERNATIONAL
IEC
STANDARD
60738-1-2
QC 440002
First edition
1998-12
Thermistors –
Directly heated positive step-function
temperature coefficient –
Part 1-2:
Blank detail specification –
Heating element application – Assessment level EZ
Thermistances à basculement à coefficient de température
positif à chauffage direct –
Partie 1-2:
Spécification particulière cadre –
Application aux éléments chauffants –
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
60738-1-2
QC 440002
First edition
1998-12
Thermistors –
Directly heated positive step-function
temperature coefficient –
Part 1-2:
Blank detail specification –
Heating element application – Assessment level EZ
Thermistances à basculement à coefficient de température
positif à chauffage direct –
Partie 1-2:
Spécification particulière cadre –
Application aux éléments chauffants –
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 – 60738-1-2 © IEC:1998(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION

TEMPERATURE COEFFICIENT –
Part 1-2: Blank detail specification –

Heating element 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 60738-1-2 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
40/1082/FDIS 40/1098/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).

60738-1-2 © IEC:1998(E) – 3 –
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION

TEMPERATURE COEFFICIENT –
Part 1-2: Blank detail specification –

Heating element 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 – 60738-1-2 © IEC:1998(E)
[1] IEC 60738-1-2-XXX [2]
QC 440002
ELECTRONIC COMPONENTS OF ASSESSED IEC 60738-1-2 [4]

QUALITY IN ACCORDANCE WITH: QC 440002

[3] DIRECTLY HEATED POSITIVE
STEP-FUNCTION TEMPERATURE
COEFFICIENT THERMISTORS [5]
Outline drawing: [see 1.2] FOR HEATING ELEMENT
[. 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.
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.

60738-1-2 © IEC:1998(E) – 5 –
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 temperatur
...