IEC 60512-16-21:2012

IEC 60512-16-21 ®
Edition 1.0 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Connectors for electronic equipment – Tests and measurements –
Part 16-21: Mechanical tests on contacts and terminations – Test 16u: Whisker
test via the application of external mechanical stresses

Connecteurs pour équipements électroniques – Essais et mesures –
Partie 16-21: Essais mécaniques des contacts et des sorties – Essai 16u: Essai
des trichites au moyen de l’application de contraintes mécaniques extérieures

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IEC 60512-16-21 ®
Edition 1.0 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Connectors for electronic equipment – Tests and measurements –

Part 16-21: Mechanical tests on contacts and terminations – Test 16u: Whisker

test via the application of external mechanical stresses

Connecteurs pour équipements électroniques – Essais et mesures –

Partie 16-21: Essais mécaniques des contacts et des sorties – Essai 16u: Essai

des trichites au moyen de l’application de contraintes mécaniques extérieures

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX L
ICS 31.220.10 ISBN 978-2-88912-057-4

– 2 – 60512-16-21 © IEC:2012
CONTENTS
FOREWORD . 3
1 Scope and object . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Test equipment . 6
4.1 Optical microscope . 6
4.2 Scanning electron microscope (SEM) . 6
5 Preparation of the specimens . 6
5.1 General . 6
5.2 Handling of the specimens . 7
5.3 Preconditioning . 7
6 Measurement of whisker length . 7
7 Test method . 8
7.1 Initial measurement . 8
7.2 Test . 8
7.2.1 General . 8
7.2.2 Test conditions . 9
7.2.3 Accelerated conditions . 9
7.2.4 Test duration . 9
7.3 Final measurement . 9
8 Requirements . 9
9 Information to be recorded. 9
10 Details to be specified . 10
Annex A (informative) Whisker growth due to mechanical stresses induced by
assembly processes and intended usage . 11

Figure 1 – Whisker length . 8
Figure A.1 – Filament whisker . 11
Figure A.2 – Whisker on contact . 11
Figure A.3 – Whisker on FFC . 11

Table 1 – Preconditioning heat treatment of specimens for whisker test . 7

60512-16-21 © IEC:2012 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CONNECTORS FOR ELECTRONIC EQUIPMENT –
TESTS AND MEASUREMENTS –
Part 16-21: Mechanical tests on contacts and terminations –
Test 16u: Whisker test via the application of
external mechanical stresses
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
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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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.
International Standard IEC 60512-16-21 has been prepared by subcommittee 48B:
Connectors, of IEC technical committee 48: Electromechanical components and mechanical
structures for electronic equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
48B/2284/FDIS 48B/2294/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.
A list of all parts of IEC series 60512, under the general title Connectors for electronic
equipment – Tests and measurements, can be found on the IEC website.

– 4 – 60512-16-21 © IEC:2012
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability 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.
60512-16-21 © IEC:2012 – 5 –
CONNECTORS FOR ELECTRONIC EQUIPMENT –
TESTS AND MEASUREMENTS –
Part 16-21: Mechanical tests on contacts and terminations
Test 16u: Whisker test via the application of
external mechanical stresses
1 Scope and object
This part of IEC 60512, when required by the detail specification, is used for testing
connectors within the scope of IEC technical committee 48. It may also be used for similar
devices when specified in a detail specification.
The object of this standard is to define a standard test method to assess the possibility of
whisker growth by external mechanical stress on the tin and tin-alloy plated parts of a
connector in its application (after wire termination, after soldering, after mounting, mated with
counterpart).
This standard does not cover internal stress type whisker.
NOTE 1 The test method dealing with internal stress type whisker, which is caused by the formation of
intermetallic compound by diffusion, or by the formation of oxide film of the plating surface, or by the difference
between coefficients of thermal expansion, is specified in IEC 60068-2-82.
While for internal stress type whisker, it is possible to apply accelerated test conditions, e.g.:
by damp heat or temperature cycling, for the external mechanical stress type whisker covered
by this standard, due to the different whisker generation mechanism, there are no accelerated
conditions. The test detailed in this standard shall then be conducted under normal ambient
conditions.
NOTE 2 Physical changes during the application process may cause changes of the material qualities, so that this
test cannot be used as a qualification test of a connector in ‘as produced’ condition.
NOTE 3 The conditions specified in this test may accelerate the growth of tin whiskers in a test specimen, but no
correlation has been demonstrated between the extent of whisker growth, which may occur in this test, and the
extent of whisker growth which may be expected in actual use. Whisker growth in actual use may therefore be less
than or greater than the extent of whisker growth found when using this test.
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 60050-581, International Electrotechnical Vocabulary (IEV) – Part 581: Electromechanical
components for electronic equipment
IEC 60068-68-1, Environmental testing – Part 1: General and guidance
IEC 60068-2-58: 2004, 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)
– 6 – 60512-16-21 © IEC:2012
IEC 60068-2-82:2007, Environmental testing – Part 2-82: Tests – Test XW : Whisker test
methods for electronic and electric components
IEC 60512-1, Connectors for electronic equipment – Tests and measurements – Part 1:
General
IEC 61760-1:2006, Surface mounting technology – Part 1: Standard method for the
specification of surface mounting components (SMDs)
3 Terms and definitions
For the purposes of this document, the terms and definitions of IEC 60050-581, IEC 60512-1,
IEC 60068-2-82 and the following additional terms and definitions apply.
3.1
whisker
metallic protrusion, which spontaneously grows from the surface of a plating on a base metal
during storage and use
Note 1 to entry: For the purpose of this standard, whiskers have the following characteristics:
– an aspect ratio (length/width) greater than 2;
– straight, kinked, bent and twisted with a uniform cross-sectional shape.
3.2
whisker length
the straight-line distance from the point of emergence of the whisker to the most distant point
on the whisker (i.e., the radius of a sphere containing the whisker with its centre located at
the point of emergence.)
4 Test equipment
4.1 Optical microscope
An optical stereomicroscope with an appropriate illumination and with at least 50X
magnification, capable of detecting whiskers with a minimum length of 10 µm shall be
provided.
For the measurement of whisker length, the microscope shall be equipped with a scale or
electronic detection system capable of length measurements with accuracy of at least ±5 µm.
4.2 Scanning electron microscope (SEM)
A SEM capable of at least 250X magnification for investigating the surface of the specimen
preferably equipped with a handling system for tilting and rotating the specimen shall be
provided.
5 Preparation of the specimens
5.1 General
The number of specimens shall be specified in the detail specification or in accordance with
IEC 60068-2-82.
The specimens shall be directly collected from the manufacturing line.

60512-16-21 © IEC:2012 – 7 –
The specimens shall be prepared as they are intended to be used in final application. The
specimens may additionally require special processing to allow observation of whisker growth,
if any, inside the specimens, without affecting the primary function of the connector.
Each test shall be performed independently on separate specimens.
5.2 Handling of the specimens
When handling the specimens, care shall be taken to prevent contamination, external
mechanical stress or unexpected damage.
In addition, care shall be taken to prevent whisker falling off.
5.3 Preconditioning
Unmated specimens shall be subjected to heat treatment.
Table 1 shows specimens preconditioning heat treatments required before whisker growth test
of Clause 7.
After heat treatment, the specimens shall be placed under standard atmospheric conditions
for at least 1 h, as specified in IEC 60068-1 to proceed to the next test.
While handling specimens, care shall be taken in order to avoid contamination of any
soldering area by contact with naked hand or other objects.
Table 1 – Preconditioning heat treatment of specimens for whisker test
Specimen Heat treatment Remarks
a b
SMT and THR connectors Test 1 or test 2 in Table 4 of The used reflow profile should be less than the
IEC 60068-2-58 maximum limited reflow profile described in

Table 4 of IEC 60068-2-58
Connectors with dip-solder 6.1 of IEC 61760-1, using The used soldering profile should be less than the
contacts or for handmade SnAgCu solder maximum limited soldering profile described in 6.1
soldering of IEC 61760-1
Connectors with solderless Not applicable
contacts
a
SMT: Surface Mount Technology.
b
THR: Through Hole Reflow.
6 Measurement of whisker length
The whisker length shall be measured according to the following procedure.
a) The specimen shall be placed on the stage of the optical microscope according to 4.1.
b) The specimen shall be observed as shown in Annex A at an appropriate magnification.
c) The length of the whisker shall be measured according to Figure 1.

– 8 – 60512-16-21 © IEC:2012
Whisker
Whisker
length
IEC  120 /12
Figure 1 – Whisker length
NOTE The length of whisker shall be measured according to its definition given in 3.2, by the straight-line
distance from the point of emergence of the whisker to the most distant point on the whisker (i.e., the radius of a
sphere containing the whisker with its centre located at the point of emergence).
For detailed observation, SEM should be used. For SEM observation, low accelerating voltage shall be applied to
avoid melting and disappearance of thin whiskers.
7 Test method
7.1 Initial measurement
Specimens shall be examined for the presence of tin whiskers using an optical microscope.
The length of each whisker identified shall be measured according to Clause 6.
The number of whiskers with a length as specified in the detail specification shall be recorded
according to Clause 10.
For detailed measurement, SEM should be used.
7.2 Test
7.2.1 General
Test shall be started with specimens subjected to mechanical stress by the mating with the
counterpart, and after specified durations, observation shall be conducted around whisker
generation area.
After initial measurement, specimens shall be subjected to the following conditions.
The specimens shall be mated and/or unmated in accordance with detail specifications.
Whisker may be generated around the external mechanical stressed areas.
Observation areas are different depending on the connector type as below.
– General purpose connector: terminal holding area and contact area.

60512-16-21 © IEC:2012 – 9 –
– FFC/FPC connector: terminal holding area, terminal contact area with FFC/FPC and
spacer.
– Wire termination, wire crimping: external areas mechanically stressed by terminating.
7.2.2 Test conditions
Temperature: 25 °C ± 10 °C
Relative humidity: 50 %RH ± 25 %RH
Duration: 1 000 h (unless otherwise specified in the detail specification)
7.2.3 Accelerated conditions
The external stress type whisker will generate and grow in normal conditions more than in
damp heat or temperature cycling conditions. Therefore there are no accelerated conditions
for external stress type whisker and the test shall be conducted in standard atmospheric
condition.
7.2.4 Test duration
In the case of FFC/FPC connectors and of crimp type wire terminations, which shall be
stressed respectively by mating or terminating, the starting time of this test shall be at the
application of the stress time. On the other hand, for general purpose connectors, which are
stressed only at the assembly time, the duration between assembly time and test starting time
shall be included in the overall test duration.
7.3 Final measurement
After 1 000 h, the specimen shall be examined for the presence of tin whiskers using an
optical microscope.
The length of each whisker identified shall be measured according to Clause 6.
The number of whiskers with a length as specified in the detail specification shall be recorded
according to Clause 10.
For detailed measurement, SEM should be used.
8 Requirements
The acceptance criteria of the whisker length shall be as specified in the detail specification.
The guideline of the acceptance length should be 1/2 of the shortest distance between
adjacent terminals.
9 Information to be recorded
The following information shall be recorded in the test report.
a) identification of the specimen:
– base material;
___________
FFC: Flexible Flat Cable; FPC : Flexible Printed Circuit.

– 10 – 60
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