IEC 62391-1:2015

IEC 62391-1 ®
Edition 2.0 2015-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Fixed electric double-layer capacitors for use in electric and electronic
equipment –
Part 1: Generic specification
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IEC 62391-1 ®
Edition 2.0 2015-10
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Fixed electric double-layer capacitors for use in electric and electronic

equipment –
Part 1: Generic specification
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.060.10 ISBN 978-2-8322-2986-6

– 2 – IEC 62391-1:2015 RLV © IEC 2015

CONTENTS
FOREWORD . 7

1 General .

1 Scope . 9

2 Normative references . 9

3 Terms and definitions . 11

4 Technical Data General items . 15

4.1 Unit and symbols . 15
4.2 Preferred values and class . 15
4.2.1 General . 15
4.2.2 Preferred values of nominal capacitance . 15
4.2.3 Class . 15
4.3 Marking . 15
4.3.1 General . 15
4.3.2 Coding . 16
4.4 Quality assessment procedures . 16
5 Tests and measurement procedures . 16
5.1 General . 16
5.2 Standard atmospheric conditions Test and measurement requirements . 16
5.2.1 Standard atmospheric conditions for testing Test conditions . 16
5.2.2 Measurement conditions . 17
5.2.3 Voltage treatment . 18
5.2.4 Thermal treatment . 18
5.3 Drying . 18
5.4 Visual examination and check of dimensions . 18
5.4.1 Visual examination . 18
5.4.2 Dimensions (gauging) . 18
5.4.3 Dimensions (detail) . 18
5.5 Measurement method 1 for capacitance and internal resistance (constant
current discharge) . 20
5.5.1 Basic circuit for measuring . 20
5.5.2 Measuring equipment . 21
5.5.3 Measuring procedure . 22

5.5.4 Calculation methods for capacitance . 24
5.5.5 Calculation methods for internal resistance. 25
5.5.6 Conditions to be prescribed in the detail specification . 26
5.6 Measurement method 2 for capacitance and internal resistance . 26
5.6.1 Constant resistance charging method for capacitance measurement . 26
5.6.2 AC internal resistance measuring method . 27
5.7 Leakage current . 29
5.7.1 Measuring method . 29
5.7.2 Items to be specified in the detail specification . 29
5.8 Self-dicharge Maintain voltage . 30
5.8.1 Measuring method . 30
5.8.2 Calculation of voltage maintenance rate . 30
5.8.3 Conditions to be prescribed in the detail specification . 31
5.9 Robustness of terminations . 31

5.9.1 Test Ua1 – Tensile . 31

5.9.2 Test Ub – Bending (half of the sample) . 31

5.9.3 Test Uc – Torsion (remaining sample) . 32

5.9.4 Test Ud – Torque (for terminations with threaded studs or screws and
for integral mounting devices) . 32

5.9.5 Visual examination . 32

5.10 Resistance to soldering heat . 32

5.10.1 Preconditioning and initial measurement . 32

5.10.2 Test . 32

5.10.3 Recovery . 33

5.10.4 Final inspection, measurements and requirements. 33
5.11 Solderability . 33
5.11.1 General . 33
5.11.2 Preconditioning . 33
5.11.3 Capacitors with leads . 33
5.11.4 Surface mount capacitors . 34
5.12 Rapid change of temperature . 35
5.12.1 Initial measurement . 35
5.12.2 Test . 35
5.12.3 Final inspection, measurements and requirements. 35
5.13 Vibration . 35
5.13.1 Initial measurement . 35
5.13.2 Test . 35
5.13.3 Final measurement and requirements . 35
5.14 Damp heat, steady state . 35
5.14.1 Initial measurement . 35
5.14.2 Test . 35
5.14.3 Final measurement . 35
5.15 Endurance . 36
5.15.1 Initial measurements . 36
5.15.2 Test . 36
5.15.3 Final measurement, inspection and requirements . 37
5.16 Storage . 37
5.16.1 Storage at high temperature . 37
5.16.2 Storage at low temperature . 37

5.17 Characteristics at high and low temperature . 37
5.17.1 General . 37
5.17.2 Test procedure . 38
5.17.3 Dry heat . 38
5.17.4 Cold. 38
5.17.5 Final measurement and requirements . 38
5.18 Component solvent resistance . 38
5.18.1 Initial measurements . 38
5.18.2 Test . 38
5.18.3 Requirements . 39
5.19 Solvent resistance of marking . 39
5.19.1 Test . 39
5.19.2 Requirements . 39
5.20 Passive flammability . 39

– 4 – IEC 62391-1:2015 RLV © IEC 2015

5.20.1 Test procedure . 39

5.20.2 Requirements . 39

5.21 Pressure relief (if applicable) . 40

5.21.1 d.c.Test . 40

5.21.2 Requirements . 40

Annex A (normative) Classification according to capacitance and internal resistance . 41

A.1 General . 41

A.2 Classification by capacitance and internal resistance . 41

Annex B (informative) Measuring method of capacitance and low resistance by low

frequency a.c. method (reference) . 44

B.0 Introduction .
B.1 General . 44
B.2 Measuring system . 44
B.3 Calculation of capacitance . 44
B.4 Measuring conditions . 45
Annex C (informative) Thermal equilibrium time of capacitors . 46
C.1 General . 46
C.2 Thermal equilibrium time of capacitors . 46
Annex D (informative) Charging/discharging efficiency and measurement current . 48
D.1 General . 48
D.2 Charging efficiency, discharging efficiency, and current . 48
Annex E (informative) Procedures for setting the measurement current of capacitor
with uncertain nominal internal resistance . 50
E.1 General . 50
E.2 Current setting procedures for measurement of capacitor . 50
E.3 Example of setting current for determining capacitor characteristics . 50
Annex F (informative) Policy on uncertainty of measurement and inset limits . 51
F.1 Objective . 51
F.2 Terms and definitions . 51
F.3 Calculation of measurement uncertainty . 51
F.4 Policy . 52
F.5 Calculation of inset and outset limits . 52
F.6 Examples . 52
F.6.1 General . 52
F.6.2 Example 1: Resistor measurement . 52

F.6.3 Example 2: Resistor measurement . 53
F.6.4 Example 3: Transistor measurement (gain) . 53
F.6.5 Example 4: Comparison between initial and final measurement results . 53
Annex G (informative) Reference to IEC 62391-1:2006 . 54
Annex Q (normative) Quality assessment procedures . 55
Q.1 General . 55
Q.1.1 Overview . 55
Q.1.2 Applicability of qualification approval . 55
Q.1.3 Applicability of capability approval . 55
Q.1.4 Applicability of technology approval . 56
Q.2 Primary stage of manufacture . 56
Q.3 Subcontracting . 56
Q.4 Structurally similar components . 56

Q.5 Qualification approval procedures . 56

Q.5.1 Eligibility for qualification approval . 56

Q.5.2 Application for qualification approval . 57

Q.5.3 Test procedure for qualification approval . 57

Q.5.4 Granting of qualification approval . 57

Q.5.5 Maintenance of qualification approval . 57

Q.5.6 Quality conformance inspection . 57

Q.6 Capability approval procedures . 57

Q.6.1 General . 57

Q.6.2 Eligibility for capability approval . 58

Q.6.3 Application for capability approval . 58
Q.6.4 Description of capability . 58
Q.6.5 Demonstration and verification of capability . 59
Q.6.6 Programme for capability approval . 59
Q.6.7 Capability approval test report . 60
Q.6.8 Abstract of description of capability . 60
Q.6.9 Modifications likely to affect the capability approval . 60
Q.6.10 Initial capability approval . 60
Q.6.11 Granting of capability approval . 61
Q.6.12 Maintenance of capability approval . 61
Q.6.13 Extension of capability approval . 62
Q.6.14 Quality conformance inspection . 62
Q.7 Rework and repair. 62
Q.7.1 Rework . 62
Q.7.2 Repair . 63
Q.8 Release for delivery . 63
Q.8.1 General . 63
Q.8.2 Release for delivery under qualification approval before the completion
of Group B tests . 63
Q.9 Certified test records of released lots . 63
Q.10 Delayed delivery . 63
Q.11 Alternative test methods . 63
Q.12 Manufacture outside the geographical limits of IECQ CBs . 63
Q.13 Unchecked parameters . 63
Q.14 Technology approval procedures . 64

Q.14.1 General . 64
Q.14.2 Eligibility for technology approval . 64
Q.14.3 Application of technology approval . 64
Q.14.4 Description of technology . 64
Q.14.5 Demonstration and verification of the technology . 64
Q.14.6 Granting of technology approval . 64
Q.14.7 Maintenance of technology approval . 64
Q.14.8 Quality conformance inspection . 64
Q.14.9 Failure rate level determination. 65
Q.14.10 Outgoing quality level . 65
Bibliography . 66

– 6 – IEC 62391-1:2015 RLV © IEC 2015

Figure 1 − Circuit for constant current discharge method .

Figure 1 − Basic circuit for measuring . 21

Figure 2 – Voltage characteristic between capacitor terminals .

Figure 2 – Voltage–time characteristics between capacitor terminals in capacitance

and internal resistance measurement . 22

Figure 3 − Circuit for constant resistance charging method . 26

Figure 4 − Circuit for a.c. resistance method . 27

Figure 5 − Voltage characteristic between capacitor terminals .

Figure 6 5 – Self-discharge Maintain voltage test diagram . 30

Figure A.1 – Conceptual rendering orientated by characteristics in each classification . 42
Figure B.1 – Capacitance measuring system by the low frequency a.c. method . 44
Figure C.1 – Thermal equilibrium times of capacitors (from 85 °C to 25 °C) . 46
Figure C.2 – Thermal equilibrium times of capacitors (from −40 °C to 25 °C) . 47
Figure C.3 – Capacitor core temperature change with respect to time . 47
Figure Q.1 – General scheme for capability approval . 58

Table 1 – Reference test: standard atmospheric conditions .
Table 1 – Measuring conditions for measuring method 1A . 23
Table 2 – Discharge conditions .
Table 2 – Measuring conditions for measuring method 1B . 24
Table 3 − Discharge current .
Table 3 – Tensile force . 31
Table 4 – Torque . 32
Table 5 – Severities and requirements . 40
Table A.1 − Measurement items for electric performance Electrical performance and
measuring method by class . 43
Table E.1 – Example of setting current for measurement of capacitor . 50

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
FIXED ELECTRIC DOUBLE-LAYER CAPACITORS

FOR USE IN ELECTRIC AND ELECTRONIC EQUIPMENT –

Part 1: Generic specification
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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6) All users should ensure that they have the latest edition of this publication.
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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.
This redline version of the official IEC Standard allows the user to identify the changes
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has been made. Additions are in green text, deletions are in strikethrough red text.

– 8 – IEC 62391-1:2015 RLV © IEC 2015

International Standard IEC 62391-1 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 2006 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) enhancement of the scope to include electric (high power) application;

b) implementation of Annex Q, replacing Clause 3 in the first edition;

c) in addition, minor revisions related to tables, figures and references.
The text of this standard is based on the following documents:
FDIS Report on voting
40/2393/FDIS 40/2415/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 62391 under the general title Fixed electric double-layer capacitors for
use in electric and electronic equipment can be found in the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
The contents of the corrigenda of December 2016 and June 2019 have been included in this copy.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
FIXED ELECTRIC DOUBLE-LAYER CAPACITORS

FOR USE IN ELECTRIC AND ELECTRONIC EQUIPMENT –

Part 1: Generic specification
1 General
1 Scope
This part of IEC 62391 applies to fixed electric double-layer capacitors (hereafter referred to
as capacitor(s)) mainly used in d.c. circuits of electric and electronic equipment.
This part of IEC 62391 establishes standard terms, inspection procedures and methods of test
for use in sectional and detail specifications of electronic components for quality assessment
or any other purpose.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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
IEC 60062, Marking codes for resistors and capacitors
IEC 60063, Preferred number series for resistors and capacitors
IEC 60068-1:1988 2013, Environmental testing – Part 1: General and guidance
Amendment 1 (1992)
IEC 60068-2-1:1990 2007, Environmental testing – Part 2-1: Tests – Tests A: Cold

Amendment 1 (1993)
Amendment 2 (1994)
IEC 60068-2-2:1974 2007, Environmental testing – Part 2-2: Tests – Tests B: Dry Heat
Amendment 1 (1993)
Amendment 2 (1994)
IEC 60068-2-6:1995 2007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration
(sinusoidal)
IEC 60068-2-14:1984 2009, Environmental testing – Part 2-14: Tests – Test N: Change of
temperature
Amendment 1 (1986)
IEC 60068-2-20:1979 2008, Environmental testing – Part 2-20: Tests – Test T: Soldering
Test methods for solderability and resistance to soldering heat of devices of with leads
Amendment 2 (1987)
– 10 – IEC 62391-1:2015 RLV © IEC 2015

IEC 60068-2-21:1999 2006, Environmental testing – Part 2-21: Tests – Test U: Robustness

of terminations and integral mounting devices

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

Immersion in cleaning solvents

Amendment 1:1993
IEC 60068-2-47:1999, Environmental testing – Part 2-47: Test methods – Mounting of

components, equipment and other articles for vibration, impact and similar dynamic tests

IEC 60068-2-54:2006, Environmental testing – Part 2-54: Tests – Test Ta: Solderbility

testing of electronic components by the wetting balance method
IEC 60068-2-58:2004 2015, 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 60068-2-69:2007, Environmental testing – Part 2-69: Tests – Test Te: Solderability
testing of electronic components for surface mounting devices (SMD) by the wetting balance
method
IEC 60068-2-78:2001 2012, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat,
steady state
IEC 60294:1969 2012, Measurement of the dimensions of a cylindrical component having
two with axial terminations
IEC 60617 (all parts) [DB] , Graphical symbols for diagrams
IEC 60695-11-5, Fire hazard testing – Part 11-5: Test flames – Needle-flame test method –
Apparatus, confirmatory test arrangement and guidance
IEC 60717:1981 2012, Method for the determination of the space required by capacitors and
resistors with unidirectional terminations
IEC 61193-2, Quality assessment systems – Part 2: Selection and use of sampling plans for
inspection of electronic components and packages
IEC 61760-1:1998, Surface mounting technology – Part 1: Standard method for the
specification of surface mounting components (SMDs)

QC001002-3, Rules of procedure – Part 3: Approval procedures
ISO 1000:1992, SI units and recommendations for the use of their multiples and of certain
other units
_____________
DB” refers to the IEC on-line database.

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 enabling them to be grouped considered together, either for qualification

approval or for quality conformance inspection; they are generally covered by a single detail

specification
Note 1 to entry: In some cases, components described in several detail specifications may be considered as
belonging to the same type.
[SOURCE: IEC 60384-1:2008, 2.2.39 – modified, the remark on "single detail specification"
was deleted from the definition and the Note was rephrased.]
3.2
style
subdivision of a type, generally based on dimensional factors
Note 1 to entry: A style may include several variants, generally of a mechanical order.
2.2.3
grade
term to indicate an additional general characteristic concerning the intended application of the
component which may only be used in combination with one or more words (e.g. long life
grade) and not by a single letter or number
3.3
class
classification of the capacitor by the capacitance value and the internal resistance value
depending upon the application
3.4
family
group of components which predominantly displays a particular
physical attribute and/or fulfils a defined function
3.5
subfamily
group of components within a family manufactured by similar
technological methods
3.6
d.c. capacitor
capacitor designed essentially for application with direct voltage
Note 1 to entry: A d.c. capacitor may not be suitable for use on a.c. supplies.
3.7
rated nominal capacitance
C C
R N
designated capacitance value usually indicated on the capacitor

– 12 – IEC 62391-1:2015 RLV © IEC 2015

3.8
category temperature range
range of ambient temperatures for which the capacitor has been designed to operate

continuously
Note 1 to entry: This is given by the lower and upper category temperature.

3.9
lower category temperature
minimum ambient temperature for which a capacitor has been designed to operate

continuously
3.10
upper category temperature
maximum highest ambient temperature for including internal heating in which a capacitor has
been is designed to operate continuously
[SOURCE: IEC 61881-3:2012, 3.17, modified – The note to entry has been deleted.]
3.11
rated temperature
maximum ambient temperature at which the rated voltage may be continuously applied
3.12
rated voltage (d.c.)
U
R
maximum direct d.c. voltage or peak value of pulse voltage which may be applied
continuously or repetitively to a capacitor at any temperature between the lower category
temperature and the rated temperature
3.13
category voltage
U
C
maximum voltage which may be applied continuously to a capacitor at its upper category
temperature
3.14
temperature derated voltage
maximum voltage that may be applied continuously to a capacitor when it is at any
temperature between the rated temperature and the upper category temperature
Note 1 to entry: Information on the voltage/temperature dependence at temperatures between the rated

temperature and the upper category temperature should, if applicable, be is given in the relevant detail
specification.
3.15
surge voltage ratio
quotient of the maximum instantaneous voltage which may be applied to the terminations of
the capacitor for a specified time at any temperature within the category temperature range
and the rated voltage or the temperature derated voltage, as appropriate
Note 1 to entry: The number of times per hour that this voltage may be applied should be is specified in the detail
specification.
3.16
rated ripple voltage
r.m.s. value of the maximum allowable alternating voltage at a specified frequency

superimposed on the d.c. voltage at which the capacitor may be operated continuously at a

specified temperature
Note 1 to entry: The sum of the direct voltage and the peak value of the alternating voltage applied to the
capacitor should does not exceed the rated voltage or temperature derated voltage, as applicable.

3.17
reverse voltage
voltage applied to the capacitor terminations in the reverse polarity

direction
3.18
rated ripple current
r.m.s. value of the maximum allowable alternating current of a specified frequency, at which
the capacitor may be operated continuously at a specified temperature
3.19
time constant
product of the internal resistance (including circuit resistance) and the capacitance
Note 1 to entry: The time constant is normally expressed in seconds.
3.20
internal resistance
resistance component in an equivalent series circuit of capacitance and resistance of a
capacitor
Note 1 to entry: The internal resistance is given in ohms (Ω).
3.21
IR drop
voltage drop between the capacitor terminals that is generated at the start of discharge and
quantified by the product of the discharge current and the internal resistance of the capacitor
3.22
maximum temperature of a capacitor
temperature at the hottest point of its external surface
Note 1 to entry: The terminations are considered as a part of the external surface.

3.23
minimum temperat
...

IEC 62391-1 ®
Edition 2.0 2015-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fixed electric double-layer capacitors for use in electric and electronic
equipment –
Part 1: Generic specification
Condensateurs électriques fixes à double couche utilisés dans les équipements
électriques et électroniques –
Partie 1: Spécification générique
IEC62391-1:2015-10(en-fr)
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IEC 62391-1 ®
Edition 2.0 2015-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fixed electric double-layer capacitors for use in electric and electronic

equipment –
Part 1: Generic specification
Condensateurs électriques fixes à double couche utilisés dans les équipements

électriques et électroniques –

Partie 1: Spécification générique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.060.10 ISBN 978-2-8322-5160-7

– 2 – IEC 62391-1:2015 © IEC 2015
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 General items . 14
4.1 Unit and symbols . 14
4.2 Preferred values and class . 14
4.2.1 General . 14
4.2.2 Preferred values of nominal capacitance . 15
4.2.3 Class . 15
4.3 Marking . 15
4.3.1 General . 15
4.3.2 Coding . 15
4.4 Quality assessment procedures . 15
5 Tests and measurement . 15
5.1 General . 15
5.2 Test and measurement requirements . 15
5.2.1 Test conditions . 15
5.2.2 Measurement conditions . 15
5.2.3 Voltage treatment . 16
5.2.4 Thermal treatment . 16
5.3 Drying . 16
5.4 Visual examination and check of dimensions . 16
5.4.1 Visual examination . 16
5.4.2 Dimensions (gauging) . 16
5.4.3 Dimensions (detail) . 16
5.5 Measurement method 1 for capacitance and internal resistance (constant
current discharge) . 16
5.5.1 Basic circuit for measuring . 16
5.5.2 Measuring equipment . 17
5.5.3 Measuring procedure . 18
5.5.4 Calculation methods for capacitance . 20
5.5.5 Calculation methods for internal resistance. 21
5.5.6 Conditions to be prescribed in the detail specification . 22
5.6 Measurement method 2 for capacitance and internal resistance . 22
5.6.1 Constant resistance charging method for capacitance measurement . 22
5.6.2 AC internal resistance measuring method . 23
5.7 Leakage current . 23
5.7.1 Measuring method . 23
5.7.2 Items to be specified in the detail specification . 24
5.8 Maintain voltage. 24
5.8.1 Measuring method . 24
5.8.2 Calculation of voltage maintenance rate . 25
5.8.3 Conditions to be prescribed in the detail specification . 25
5.9 Robustness of terminations . 25
5.9.1 Test Ua1 – Tensile . 25
5.9.2 Test Ub – Bending (half of the sample) . 25

5.9.3 Test Uc – Torsion (remaining sample) . 26
5.9.4 Test Ud – Torque (for terminations with threaded studs or screws and
for integral mounting devices) . 26
5.9.5 Visual examination . 26
5.10 Resistance to soldering heat . 26
5.10.1 Preconditioning and initial measurement . 26
5.10.2 Test . 26
5.10.3 Recovery . 26
5.10.4 Final inspection, measurements and requirements. 27
5.11 Solderability . 27
5.11.1 General . 27
5.11.2 Preconditioning . 27
5.11.3 Capacitors with leads . 27
5.11.4 Surface mount capacitors . 28
5.12 Rapid change of temperature . 28
5.12.1 Initial measurement . 28
5.12.2 Test . 28
5.12.3 Final inspection, measurements and requirements. 28
5.13 Vibration . 28
5.13.1 Initial measurement . 28
5.13.2 Test . 28
5.13.3 Final measurement and requirements . 29
5.14 Damp heat, steady state . 29
5.14.1 Initial measurement . 29
5.14.2 Test . 29
5.14.3 Final measurement . 29
5.15 Endurance . 29
5.15.1 Initial measurements . 29
5.15.2 Test . 29
5.15.3 Final measurement, inspection and requirements . 29
5.16 Storage . 30
5.16.1 Storage at high temperature . 30
5.16.2 Storage at low temperature . 30
5.17 Characteristics at high and low temperature . 30
5.17.1 General . 30
5.17.2 Test procedure . 30
5.17.3 Dry heat . 31
5.17.4 Cold. 31
5.17.5 Final measurement and requirements . 31
5.18 Component solvent resistance . 31
5.18.1 Initial measurements . 31
5.18.2 Test . 31
5.18.3 Requirements . 31
5.19 Solvent resistance of marking . 31
5.19.1 Test . 31
5.19.2 Requirements . 32
5.20 Passive flammability . 32
5.20.1 Test procedure . 32
5.20.2 Requirements . 32

– 4 – IEC 62391-1:2015 © IEC 2015
5.21 Pressure relief (if applicable) . 32
5.21.1 Test . 32
5.21.2 Requirements . 32
Annex A (normative) Classification according to capacitance and internal resistance . 33
A.1 General . 33
A.2 Classification by capacitance and internal resistance . 33
Annex B (informative) Measuring method of capacitance and low resistance by low
frequency a.c. method (reference) . 35
B.1 General . 35
B.2 Measuring system . 35
B.3 Calculation of capacitance . 35
B.4 Measuring conditions . 36
Annex C (informative) Thermal equilibrium time of capacitors . 37
C.1 General . 37
C.2 Thermal equilibrium time of capacitors . 37
Annex D (informative) Charging/discharging efficiency and measurement current . 39
D.1 General . 39
D.2 Charging efficiency, discharging efficiency, and current . 39
Annex E (informative) Procedures for setting the measurement current of capacitor
with uncertain nominal internal resistance . 41
E.1 General . 41
E.2 Current setting procedures for measurement of capacitor . 41
E.3 Example of setting current for determining capacitor characteristics . 41
Annex F (informative) Policy on uncertainty of measurement and inset limits . 42
F.1 Objective . 42
F.2 Terms and definitions . 42
F.3 Calculation of measurement uncertainty . 42
F.4 Policy . 43
F.5 Calculation of inset and outset limits . 43
F.6 Examples . 43
F.6.1 General . 43
F.6.2 Example 1: Resistor measurement . 43
F.6.3 Example 2: Resistor measurement . 44
F.6.4 Example 3: Transistor measurement (gain) . 44
F.6.5 Example 4: Comparison between initial and final measurement results . 44
Annex G (informative) Reference to IEC 62391-1:2006 . 45
Annex Q (normative) Quality assessment procedures . 46
Q.1 General . 46
Q.1.1 Overview . 46
Q.1.2 Applicability of qualification approval . 46
Q.1.3 Applicability of capability approval . 46
Q.1.4 Applicability of technology approval . 47
Q.2 Primary stage of manufacture . 47
Q.3 Subcontracting . 47
Q.4 Structurally similar components . 47
Q.5 Qualification approval procedures . 47
Q.5.1 Eligibility for qualification approval . 47
Q.5.2 Application for qualification approval . 48

Q.5.3 Test procedure for qualification approval . 48
Q.5.4 Granting of qualification approval . 48
Q.5.5 Maintenance of qualification approval . 48
Q.5.6 Quality conformance inspection . 48
Q.6 Capability approval procedures . 48
Q.6.1 General . 48
Q.6.2 Eligibility for capability approval . 49
Q.6.3 Application for capability approval . 49
Q.6.4 Description of capability . 49
Q.6.5 Demonstration and verification of capability . 50
Q.6.6 Programme for capability approval . 50
Q.6.7 Capability approval test report . 51
Q.6.8 Abstract of description of capability . 51
Q.6.9 Modifications likely to affect the capability approval . 51
Q.6.10 Initial capability approval . 51
Q.6.11 Granting of capability approval . 52
Q.6.12 Maintenance of capability approval . 52
Q.6.13 Extension of capability approval . 53
Q.6.14 Quality conformance inspection . 53
Q.7 Rework and repair. 53
Q.7.1 Rework . 53
Q.7.2 Repair . 54
Q.8 Release for delivery . 54
Q.8.1 General . 54
Q.8.2 Release for delivery under qualification approval before the completion
of Group B tests . 54
Q.9 Certified test records of released lots . 54
Q.10 Delayed delivery . 54
Q.11 Alternative test methods . 54
Q.12 Manufacture outside the geographical limits of IECQ CBs . 54
Q.13 Unchecked parameters . 54
Q.14 Technology approval procedures . 55
Q.14.1 General . 55
Q.14.2 Eligibility for technology approval . 55
Q.14.3 Application of technology approval . 55
Q.14.4 Description of technology . 55
Q.14.5 Demonstration and verification of the technology . 55
Q.14.6 Granting of technology approval . 55
Q.14.7 Maintenance of technology approval . 55
Q.14.8 Quality conformance inspection . 55
Q.14.9 Failure rate level determination. 56
Q.14.10 Outgoing quality level . 56
Bibliography . 57

Figure 1 − Basic circuit for measuring . 17
Figure 2 – Voltage–time characteristics between capacitor terminals in capacitance
and internal resistance measurement . 18
Figure 3 − Circuit for constant resistance charging method . 22
Figure 4 − Circuit for a.c. resistance method . 23

– 6 – IEC 62391-1:2015 © IEC 2015
Figure 5 − Maintain voltage test diagram . 24
Figure A.1 – Conceptual rendering orientated by characteristics in each classification . 34
Figure B.1 – Capacitance measuring system by the low frequency a.c. method . 35
Figure C.1 – Thermal equilibrium times of capacitors (from 85 °C to 25 °C) . 37
Figure C.2 – Thermal equilibrium times of capacitors (from −40 °C to 25 °C) . 38
Figure C.3 – Capacitor core temperature change with respect to time . 38
Figure Q.1 – General scheme for capability approval . 49

Table 1 – Measuring conditions for measuring method 1A . 19
Table 2 – Measuring conditions for measuring method 1B . 20
Table 3 – Tensile force . 25
Table 4 – Torque . 26
Table 5 – Severities and requirements . 32
Table A.1 – Electrical performance and measuring method by class . 34
Table E.1 – Example of setting current for measurement of capacitor . 41

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIXED ELECTRIC DOUBLE-LAYER CAPACITORS
FOR USE IN ELECTRIC AND ELECTRONIC EQUIPMENT –

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-
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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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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 62391-1 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.
This bilingual version (2017-12) corresponds to the monolingual English version, published in
2015-10.
This second edition cancels and replaces the first edition published in 2006 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) enhancement of the scope to include electric (high power) application;
b) implementation of Annex Q, replacing Clause 3 in the first edition;

– 8 – IEC 62391-1:2015 © IEC 2015
c) in addition, minor revisions related to tables, figures and references.
The text of this standard is based on the following documents:
FDIS Report on voting
40/2393/FDIS 40/2415/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 62391 under the general title Fixed electric double-layer capacitors for
use in electric and electronic equipment can be found in the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
The contents of the corrigenda of December 2016 and June 2019 have been included in this copy.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
FIXED ELECTRIC DOUBLE-LAYER CAPACITORS
FOR USE IN ELECTRIC AND ELECTRONIC EQUIPMENT –

Part 1: Generic specification
1 Scope
This part of IEC 62391 applies to fixed electric double-layer capacitors (hereafter referred to
as capacitor(s)) mainly used in d.c. circuits of electric and electronic equipment.
This part of IEC 62391 establishes standard terms, inspection procedures and methods of test
for use in sectional and detail specifications of electronic components for quality assessment
or any other purpose.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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
IEC 60062, Marking codes for resistors and capacitors
IEC 60063, Preferred number series for resistors and capacitors
IEC 60068-1:2013, Environmental testing – Part 1: General and guidance
IEC 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Tests A: Cold
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Tests B: Dry Heat
IEC 60068-2-6:2007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-14:2009, Environmental testing – Part 2-14: Tests – Test N: Change of
temperature
IEC 60068-2-20:2008, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices of with leads
IEC 60068-2-21:2006, Environmental testing – Part 2-21: Tests – Test U: Robustness of
terminations and integral mounting devices
IEC 60068-2-45:1980, Environmental testing – Part 2-45: Tests – Test XA and guidance:
Immersion in cleaning solvents
Amendment 1:1993)
– 10 – IEC 62391-1:2015 © IEC 2015
IEC 60068-2-54:2006, Environmental testing – Part 2-54: Tests – Test Ta: Solderbility
testing of electronic components by the wetting balance method
IEC 60068-2-58:2015, 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 60068-2-69:2007, Environmental testing – Part 2-69: Tests – Test Te: Solderability
testing of electronic components for surface mounting devices (SMD) by the wetting balance
method
IEC 60068-2-78:2012, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat,
steady state
IEC 60294:2012, Measurement of the dimensions of a cylindrical component with axial
terminations
IEC 60617 (all parts), Graphical symbols for diagrams
IEC 60695-11-5, Fire hazard testing – Part 11-5: Test flames – Needle-flame test method –
Apparatus, confirmatory test arrangement and guidance
IEC 60717:2012, Method for the determination of the space required by capacitors and
resistors with unidirectional terminations
IEC 61193-2, Quality assessment systems – Part 2: Selection and use of sampling plans for
inspection of electronic components and packages
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 manufacturing techniques, enabling
them to be considered together, either for qualification approval or for quality conformance
inspection
Note 1 to entry: In some cases, components described in several detail specifications may be considered as
belonging to the same type.
[SOURCE: IEC 60384-1:2008, 2.2.39 – modified, the remark on "single detail specification"
was deleted from the definition and the Note was rephrased.]
3.2
style
subdivision of a type, generally based on dimensional factors
Note 1 to entry: A style may include several variants, generally of a mechanical order.
3.3
class
classification of the capacitor by the capacitance value and the internal resistance value
depending upon the application

3.4
family
group of components which predominantly displays a particular
physical attribute and/or fulfils a defined function
3.5
subfamily
group of components within a family manufactured by similar
technological methods
3.6
d.c. capacitor
capacitor designed essentially for application with direct voltage
Note 1 to entry: A d.c. capacitor may not be suitable for use on a.c. supplies.
3.7
nominal capacitance
C
N
designated capacitance value usually indicated on the capacitor
3.8
category temperature range
range of ambient temperatures for which the capacitor has been designed to operate
continuously
Note 1 to entry: This is given by the lower and upper category temperature.
3.9
lower category temperature
minimum ambient temperature for which a capacitor has been designed to operate
continuously
3.10
upper category temperature
highest ambient temperature including internal heating in which a capacitor is designed to
operate continuously
[SOURCE: IEC 61881-3:2012, 3.17, modified – The note to entry has been deleted.]
3.11
rated temperature
maximum ambient temperature at which the rated voltage may be continuously applied
3.12
rated voltage
U
R
maximum d.c. voltage or peak value of pulse voltage which may be applied continuously or
repetitively to a capacitor at any temperature between the lower category temperature and the
rated temperature
3.13
category voltage
U
C
maximum voltage which may be applied continuously to a capacitor at its upper category
temperature
– 12 – IEC 62391-1:2015 © IEC 2015
3.14
temperature derated voltage
maximum voltage that may be applied continuously to a capacitor when it is at any
temperature between the rated temperature and the upper category temperature
Note 1 to entry: Information on the voltage/temperature dependence at temperatures between the rated
temperature and the upper category temperature is given in the detail specification.
3.15
surge voltage ratio
quotient of the maximum instantaneous voltage which may be applied to the terminations of
the capacitor for a specified time at any temperature within the category temperature range
and the rated voltage or the temperature derated voltage, as appropriate
Note 1 to entry: The number of times per hour that this voltage may be applied is specified in the detail
specification.
3.16
rated ripple voltage
r.m.s. value of the maximum allowable alternating voltage at a specified frequency
superimposed on the d.c. voltage at which the capacitor may be operated continuously at a
specified temperature
Note 1 to entry: The sum of the direct voltage and the peak value of the alternating voltage applied to the
capacitor does not exceed the rated voltage or temperature derated voltage, as applicable.
3.17
reverse voltage
voltage applied to the capacitor terminations in the reverse polarity
direction
3.18
rated ripple current
r.m.s. value of the maximum allowable alternating current of a specified frequency, at which
the capacitor may be operated continuously at a specified temperature
3.19
time constant
product of the internal resistance (including circuit resistance) and the capacitance
Note 1 to entry: The time constant is normally expressed in seconds.
3.20
internal resistance
resistance component in an equivalent series circuit of capacitance and resistance of a
capacitor
Note 1 to entry: The internal resistance is given in ohms (Ω).
3.21
IR drop
voltage drop between the capacitor terminals that is generated at the start of discharge and
quantified by the product of the discharge current and the internal resistance of the capacitor
3.22
maximum temperature of a capaci
...