IEC 60738-1-2:2008

IEC 60738-1-2 ®
Edition 2.0 2008-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thermistors – Directly heated positive step-function temperature coefficient –
Part 1-2: Blank detail specification – Heating element application – Assessment
level EZ
Thermistances – Coefficient de température positif de fonction échelon à
chauffage direct –
Partie 1-2: Spécification particulière cadre – Application de l'élément chauffant –
Niveau d'assurance de la qualité EZ

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IEC 60738-1-2 ®
Edition 2.0 2008-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Thermistors – Directly heated positive step-function temperature coefficient –

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

level EZ
Thermistances – Coefficient de température positif de fonction échelon à

chauffage direct –
Partie 1-2: Spécification particulière cadre – Application de l'élément chauffant –

Niveau d'assurance de la qualité EZ

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX M
ICS 31.040.30 ISBN 978-2-8322-1317-9

– 2 – 60738-1-2  IEC:2008
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 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
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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 60738-1-2 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.
This second edition cancels and replaces the first edition issued in 1998. It constitutes a
technical revision.
This edition contains changes with respect to the referenced subclauses of the revised generic
specification IEC 60738-1.
This publication is to be read in conjunction with IEC 60738-1.

60738-1-2  IEC:2008 – 3 –
This bilingual version (2014-01) corresponds to the monolingual English version, published in
2008-02.
The text of this standard is based on the following documents:
FDIS Report on voting
40/1875/FDIS 40/1892/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 French version of this standard has not been voted upon.
The list of all parts of the IEC 60738 series, under the (new) general title Thermistors – Directly
heated positive step-function temperature coefficient, can be found on the IEC website.
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.
– 4 – 60738-1-2  IEC:2008
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 IEC 60738-1:2006, 1.4 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.
60738-1-2  IEC:2008 – 5 –
[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]
[9]
Information on the availability of components
qualified to this detail specification is given in
the Register of Approvals.
– 6 – 60738-1-2  IEC:2008
THERMISTORS –
DIRECTLY HEATED POSITIVE STEP-FUNCTION
TEMPERATURE COEFFICIENT –
Part 1-2: Blank detail specification –
Heating element application –
Assessment level EZ
1 General data
1.1 Method(s) of mounting (to be inserted)
(See IEC 60738-1:2006, 7.30).
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 thermistor is insulated or non-insulated,
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.

60738-1-2  IEC:2008 – 7 –
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
);
Switching temperature (T
b
Either inrush current (I );
in
or minimum resistance (R );
.
min
Either residual current (I );
res
or
Resistance(R );
p
or
) .
Final surface temperature (T
FS
1.9 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 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 60410:1973, Sampling plans and procedures for inspection by attributes
IEC 60738-1:2006, 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 IEC 60738-1:2006, 5.2.
The details of the marking of the thermistors and package containing the thermistor shall be
given in full in the detail specification.
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.
___________
Test method shall be given in the detail specification.

– 8 – 60738-1-2  IEC:2008
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 60738-1:2006, 6.5.
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 the
generic specification IEC 60738-1:2006, 6.5.7.
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 60738-1:2006, and clause 1 of this document.
2) Number to be tested: sample size as directly allotted to the code letter for IL in Table IIA of
IEC 60410:1973 (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 60068-2-58 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.
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
–6
quality level by non-conforming items per million (× 10 ). The sampling level shall be
–6
established by the manufacturer. For the calculation of × 10 values any parametric
failure shall be counted as a non-conforming item. In case one or more non-conforming
items occur in a sample, this lot shall be rejected.

60738-1-2  IEC:2008 – 9 –
Table 1 – Test schedule for quality conformance inspection: lot-by-lot
Subclause number and D Conditions of test IL n c Performance
test or requirements
(see list item 1)
(see list item 1) ND (see list item 1)
(see list item 3)
GROUP A INSPECTION
(lot-by-lot)
ND 100 %
Subgroup A0
(see list item 12)
Temperature:. °C As in 7.5.3
7.5 Zero-power
resistance R Voltage:. V
T
Frequency:. Hz
Subgroup A1 ND S-4 (see 0
item
list 2) As in 7.4.1
7.4.1 Visual
examination
Subgroup A2 ND S-3 (see 0
item
7.4.2 Marking list 2) As in 7.4.2

7.4.3 Dimensions As specified in the detail
specification
(gauging)
GROUP B INSPECTION
(lot-by-lot)
ND S-2 (see 0
Subgroup B1
item
See detail specification list 2)
7.28 Surface tempe-
rature after 20 min
(if specified)
7.29 Maximum inrush Voltage:. V
current
(if specified)
7.27 Residual current
I ≤. mA
res
(if specified)
Subgroup B2 ND S-2 (see 0
item
(Insulated thermistors
7.8 Voltage proof list 2) As in 7.8.4
only)
Method:.
Applied voltage:. V a.c.
(see list item 6 and 7)
7.16 Solderability The terminations shall be
Solder bath method uniformly tinned

– 10 – 60738-1-2  IEC:2008
Table 2 – Test schedule for quantity conformance inspection: periodic
Subclause number D Conditions of test Sample size Performance
and test or and requirements
(see list item 1)
(see list item 1) ND acceptance (see list item 1)
criterion
(see list item 3)
p n c
GROUP C INSPECTION
(periodic)
Subgroup C1A D (see list item 6 and 7) 6 5 0

Part of sample
As in 7.17.4 and 7.17.5
Temperature:. °C
7.17 Resistance to
Visual examination ∆R/R: from. % to. %
soldering heat
Zero-power resistance
(Temperature:. °C)
(Voltage:. V)
7.15 Robustness of Tensile, bending and
terminations torsion tests as appropriate

to type of terminations,
if applicable
Visual examination As in 7.15.4 and 7.15.5
Zero-power resistance ∆R/R: from. % to. %
(Temperature:. °C)
(Voltage:. V)
D 6 5
Subgroup C1B
Other part of sample
7.18 Rapid change of 2 = LCT
A
temperature 2 = LCT
B
As in 7.18
Visual examination
∆R/R: from. % to. %
Zero-power resistance
(Temperature:. °C)
(Voltage:. V)
7.19 Vibration  Frequency range:
... Hz to... Hz
Amplitude: 0,75 mm or
acceleration: 98 m/s
(whichever is the less
severe)
Sweep endurance
Total duration: 6 h
Number of sweep cycles:
see 5.1.3
Final measurements:
Visual examination As in 7.19
Zero-power resistance
∆R/R: from. % to. %
(Temperature:. °C)
(Voltage:. V)
7.20
Acceleration:. m/s
Bump (or shock,
Number of bumps:.
see list item 9) (see list item 8)

Visual examination As in 7.20
Zero-power resistance ∆R/R: from. % to.

(Temperature:. °C)
(Voltage:. V)
60738-1-2  IEC:2008 – 11 –
Table 2 (continued)
Subclause number D Conditions of test Sample size Performance
and test or and requirements
(see list item 1)
(see list item 1) ND acceptance (see list item 1)
criterion
(see list item 3)
p n c
7.21 Shock (or bump, Pulse shape: halfsine
see list item 9) Acceleration:. m/s

(see list item 8)
Pulse duration:. ms
Visual examination
As in 7.21
Zero-power resistance
∆R/R: from. % to. %
(Temperature:. °C)
(Voltage:. V)
Subgroup C1 D 6 10
Combined sample of
specimens of sub-
groups C1A and C1B
(Low air pressure test not
7.22 Climatic
applicable)
sequence
– Dry heat
– Damp heat,
cyclic, first cycle
– Cold
– Damp heat,
cyclic, remaining
cycles
Visual examination As in 7.22.7
– Final measure-
Zero-power resistance
∆R/R: from. % to. %
ments
(Temperature:. °C)
(Voltage:. V)
Insulation resistance R ≥. MΩ
(Insulated thermistors only)
Voltage proof
As in 7.22.7
(Insulated thermistors only)
ND 6 10 0
Subgroup C2
Method:. As specified in the detail
7.14 Thermal time
specification
constant by T :. °C
cooling
T :. °C
(if applicable)
Thermal time constant
Subgroup C3 ND (see list item 5) 6 10 0

7.6 Temperature T :. °C α : (from. to.) %/K
p R
coefficient of
T :. °C
b
resistance (if
Voltage:. V
applicable)
7.4.4 As specified in the detail

Dimensions
specification
(detail)
As specified in the detail
Dissipation factor
7.10 Dissipation fac- specification
tor at U (if
max.
specified) (see
list item 11)
– 12 – 60738-1-2  IEC:2008
Table 2 (continued)
Subclause number D Conditions of test Sample size Performance
and test or and requirements
(see list item 1)
(see list item 1) ND acceptance (see list item 1)
criterion
(see list item 3)
p n c
Subgroup C4 D (see list item 10) 6 10 0

(The detail specification
7.24.3 Endurance at
maximum opera- shall describe the method
ting temperature of mounting, see 7.24.3)
and maximum
Duration:. h
voltage
Examination at 168 h and
500 h (if applicable)
Zero-power resistance
∆R/R: from. % to. %
(Temperature:. °C)
(Voltage:. V)
Examination at. h
Visual examination As in 7.24.3
Zero-power resistance
∆R/R: from. %
...