IEC PAS 62137-3:2008

IEC/PAS 62137-3
Edition 1.0 2008-11
PUBLICLY AVAILABLE
SPECIFICATION
PRE-STANDARD

Electronics assembly technology – Selection guidance of environmental and
endurance test methods for solder joints


IEC/PAS 62137-3:2008(E)

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IEC/PAS 62137-3
Edition 1.0 2008-11
PUBLICLY AVAILABLE
SPECIFICATION
PRE-STANDARD

Electronics assembly technology – Selection guidance of environmental and
endurance test methods for solder joints
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 31.190 ISBN 978-2-88910-809-1
® Registered trademark of the International Electrotechnical Commission

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– 2 – PAS 62137-3 © IEC:2008(E)

CONTENTS

FOREWORD.4
INTRODUCTION.5
1 Scope.6
2 Normative references .7
3 Terms and definitions .8
4 Procedure of selecting the applicable test method .9
4.1 Stress to solder joints in the field and test methods .9
4.2 Selection of test methods based on the shapes and terminals of electronic
components.11
5 Common subjects in each test method .12
5.1 Mounting device and materials used.12
5.2 Soldering condition.13
5.3 Accelerated endurance test .15
5.4 Selection of test conditions and analysis of test results .15
6 Test method .16
6.1 Body strength test of SMD before and after the rapid temperature change test.16
6.2 Cyclic bending strength test .18
6.3 Mechanical shear fatigue test .19
6.4 Cyclic drop test .20
6.5 Strength test of leaded component .22
6.6 Fillet lifting phenomenon observation of leaded component .23
Annex A (informative) Condition of rapid temperature change test .24
Annex B (informative) Soldered joint test by electrical conduction.26
Annex C (informative)  Torque shear strength test .27
Annex D (informative) Monotonic bending strength test .30
Annex E (informative) Cyclic steel ball drop strength test .32
Annex F (informative) Pull strength test.34
Annex G (informative) Creep strength test.35
Annex H (informative) Fillet lifting phenomenon observation of leaded component solder
joint and the life test by electrical conduction.40

Figure 1 – The joint regions for the reliability tests .6
Figure 2 – Factors affecting the joint reliability made by lead-free solder .7
Figure 3 – An example of the mounting position of SMD for monotonic bending, cyclic
bending and cyclic drop tests.13
Figure 4 – An example of reflow soldering temperature profile .14
Figure 5 – An example of flow soldering temperature profile .14
Figure 6 – Pull strength test.16
Figure 7 – Shear strength test.17
Figure 8 – Torque shear strength test .17
Figure 9 – Monotonic bending strength test .18
Figure 10 – Cyclic bending strength test .19

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PAS 62137-3 © IEC:2008(E) – 3 –
Figure 11 – Structure of cyclic bending strength test.19
Figure 12 – Schematic illustrations of mechanical shear fatigue for solder joint .20
Figure 13 – Cyclic drop test .21
Figure 14 – Cyclic steel ball drop test .21
Figure 15 – Pull strength test .22
Figure 16 – Creep strength test .23
Figure 17 – Fillet lifting phenomenon of soldered joint .23
Figure A.1 – Stress relation curve for a given strain to a soldered joint (Sn96,5Ag3Cu,5) .24
Figure A.2 – Time to reach steady state in the temperature cycle chamber .25
Figure B.1 – Soldered joint test by electrical conduction .26
Figure C.1 – Fixing of substrate for torque shear strength test .29
Figure C.2 – Torque shear strength test jig and position adjustment .29
Figure C.3 – Torque shear strength test to a connector.29
Figure D.1 – An example of board bending jig.30
Figure E.1 – Cyclic steel ball drop test.32
Figure E.2 – Comparison of cyclic drop test and cyclic steel ball drop test .33
Figure F.1 – Pull strength test.34
Figure G.1 – Schematic illustration of the creep strength of a soldered joint .35
Figure G.2 – An example of flow soldering temperature profile (Actual measurement for
double wave soldering) .38
Figure G.3 – Creep strength test.39
Figure H.1 – Fillet lifting phenomenon of soldered joint.40
Figure H.2 – Conduction measurement for Fillet lifting phenomenon .41

Table 1 – Correlations between test methods and actual stresses in the filed .10
Table 2 – Recommended test methods suitable for specific shapes and terminals of
SMDs.11
Table 3 – Test method to recommend from application and weight of the lead terminal part.12
Table 4 – Solder composition.12
Table 5 – Temperature condition for rapid temperature change test.15
Table G.1 – Nominal cross section of leads and diameters of through holes and lands .37
Table H.1 – Diameters of through holes and lands in respect to the nominal cross
section and nominal diameter of lead wire .41

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– 4 – PAS 62137-3 © IEC:2008(E)

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONICS ASSEMBLY TECHNOLOGY –
SELECTION GUIDANCE OF ENVIRONMENTAL
AND ENDURANCE TEST METHODS
FOR SOLDER JOINTS
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,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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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.
A PAS is a technical specification not fulfilling the requirements for a standard but made
available to the public.
IEC-PAS 62137-3 was submitted by the JEITA (Japan Electronics and Information Technology
Industries Association) and has been processed by IEC technical committee 91: Electronics
assembly technology.
The text of this PAS is based on This PAS was approved for
the following documents publication by the P-members of the
committee concerned as indicated in
the following document:
Draft PAS Report on voting
91/784/DPAS 91/821/RVD
Following publication of this PAS, which is a pre-standard publication, the technical committee
or subcommittee concerned will transform it into an International Standard.
This PAS shall remain valid for an initial maximum period of three years starting from the
publication date. The validity may be extended for a single three-year period, following which it
shall be revised to become another type of normative document or shall be withdrawn.

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PAS 62137-3 © IEC:2008(E) – 5 –
INTRODUCTION
Tin-Lead eutectic solder had been used for both internal and external joints of electric and
electronic equipment for its characteristics and cost for long time. The recent request to reduce
burdens to the environment, however, resulted in various types of lead-free solders being
developed by many organizations. Now the solders used in production are being switched from
tin-lead based solders to lead-free solders in many production lines. The study of the solder
joints using lead-free solders has revealed that the reliability of the joints is not the same as that
of joints prepared using tin-lead solder. The Japan Electronics & Information Technology
Industries Association (JEITA) has been developing test methods to evaluate the performance
of the joints based on analysis of various experiments made by member experts. It should be
noted that any single test is not necessarily applicable to all the electronic components. There
are appropriate tests suitable for the size and shape of a component and also for specific types
of leads of components. This series of standards are thus prepared to provide the industry with
the necessary evaluation methods to produce reliable products to the society.

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– 6 – PAS 62137-3 © IEC:2008(E)

ELECTRONICS ASSEMBLY TECHNOLOGY –
SELECTION GUIDANCE OF ENVIRONMENTAL
AND ENDURANCE TEST METHODS
FOR SOLDER JOINTS

1 Scope
This guidance describes the selection of an appropriate test method for reliability test of solder
joints for various shapes and types of surface mount devices (SMD) and leaded devices,
including various types of solder material.
The regions of the joints to be tested are shown in Figure 1. The test methods given here are
applicable to evaluate the strength of joints of a component mounted on printed wiring board but
not to test the mechanical strength of components themselves.
The test conditions for accelerated tests (rapid temperature change and high temperature tests)
may exceed the maximum allowable temperature range for a component.

SMD (leadless electrode type)
Component terminal
Component
Solder
Component terminal
Plating layers
Evaluation
Solder
Intermetallic
area
Compound layers

Substrate
Land Substrate land
Substrate
SMD (leaded type)
Component terminal
Solder
Component
terminal

Plating layers
Land
Substrate
Evaluation
Solder Intermetallic
area
Insertion type co mponent
Compound layers
(single-sided board)
Lead terminal
Substrate land
Substrate
Substrate
Solder
Land

Figure 1 – The joint regions for the reliability tests
The lead-free solders have different properties from those of the conventional tin-lead eutectic
solder. The reliability of soldered joints using lead-free solder may be reduced by the
composition of the solder used, the shape of terminals and surface treatment.

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PAS 62137-3 © IEC:2008(E) – 7 –
The factors affecting the joint reliability using Sn96,5Ag3Cu,5 solder are shown in Figure 2.
This solder has the properties of higher melting temperature and harder than the tin-lead
eutectic solder and the solid is not easily deformed. Consequently, the stress induced to the
joint becomes higher than the tin-lead eutectic solder.
These properties may induce break of a soldered joint by accelerated temperature changes, or
mechanical stress.
Accelerating factors
Temperature cycle
Properties
   (thermal stress)
Factors affecting joint reliability
Mechanical stress
1)Hard, not easily deformed      Increased stress to solder
Impact stress
2)High melting temp.      Increased stress between
Weight/load of component
  High solidifying temp.       Joint/ substrate (e.g., fillet lifting)
  High soldering temp.      Growth of reacting layer
3)Increased reactivity (Sn rich)      Electrode/land melting, diffusion
4)Segregation by inclusion of low           Reduction of reliability by formation of
melting temp. metals (Pb, Bi)  segregation layer
Solder failure
5)Change in materials/structure      Failure of electrode itself
Initiation and
Interface failure
  of terminals growth of crack
Electrode failure
6)Decreased solderability      Deformation of fillet, defect formation
and fracture *Not of component
and board
Affecting parameter
Component: structure of terminals
 Size
Board: Land, thickness, material
Structure of joints

Figure 2 – Factors affecting the joint reliability made
by lead-free solder
2 Normative references
The following referenced documents are indispensable for the application of this document. For
a dated reference, only the edition cited applies. For an undated reference, the latest edition of
the referenced document (including any amendment) applies.
IEC 60068-1:1988, Environmental testing. Part 1: General and guidance,
Amendment 1:1992
IEC 60068-2-2:2007, Basic environmental testing procedures Part 2:Tests, Test B: Dry heat
IEC 60068-2-14:1984, Environmental testing – Part 2: Test N: Change of Temperature
Amendment 1:1986
IEC 60068-2-78:2001 Environmental testing – Part:2-78: Tests – Test: Cab: Damp heat, steady
state
IEC 60194:2006, Printed board design, manufacture and assembly – Terms and definitions
IEC 61188-5(all parts) :Printed boards and printed board assemblies – Design and use
IEC 61190-1-1:2002, Attachment materials for electronic assembly – Part 1-1 Requirements for
soldering fluxes for high-quality interconnections in electronics assembly
IEC 61190-1-2:2007, Attachment materials for electronic assembly – Part 1-2 Requirements for
solder pastes for high-quality interconnections in electronics assembly

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– 8 – PAS 62137-3 © IEC:2008(E)

IEC 61249-2-7:2002, Materials for printed boards and other interconnecting structure – Part 2-7;
Reinforced base materials clad and unclad – Epoxide woven E-glass laminated sheet of defined
flammability (vertical burning test), copper-clad
IEC 62137:2005, Environmental and endurance testing – Test methods for surface-mount
boards of area array type packages FBGA, BGA, FLGA, LGA, SON and QFN
IEC 62137-1-1:2007, Surface mounting technology – Environmental and endurance test
methods for surface mount solder joint – Part 1-1: Pull strength test
IEC 62137-1-2:2007, Surface mounting technology – Environmental and endurance test
methods for surface mount solder joint – Part1-2: Shear strength test
IEC 62137-1-3(91/708/CDV), Surface-mount technology – Environmental and endurance test
methods for surface mount solder joint – Part 1-3: Cyclic drop test
IEC 62137-1-4(91/746/CDV), Surface mounting technology – Environmental and endurance test
methods for surface mount solder joints – Part 1-4: Cyclic bending test
IEC 62137-1-5(91/743/CDV), Surface mounting technology – Environmental and endurance test
methods for surface mount solder joints – Part 1-5: Mechanical shear fatigue test
3 Terms and definitions
For the purposes of this document, the terms and definitions in IEC 60194, as well as the
following, apply.
3.1
lead-free
the lead content in the objective portion of an electronic components or similar products is equal
or less than 0,1 wt%
3.2
pull strength for SMD
applied force to break the joint of the lead of a gull-wing type SMD solder mounted and the
copper land of printed wiring board using a jig to pull the lead
3.3
shear strength for SMD
applied force to break the all the joints of leads of an SMD and lands on the printed wiring board
when a force is applied parallel to the side of the SMD
3.4
torque shear strength for SMD
applied force to break the soldered joints of leads of an SMD to the lands on printed wiring
board when a rotating force is applied to the SMD at the both end with the centre of the moment
at the center of the SMD with the rotation moment in parallel to the printed wiring board surface
3.5
monotonic bending strength for SMD
strength of soldered joints of SMD mounted on board when the board is bent convex toward to
the mounted SMDs expressed by the maximum bending depth to the break of joints

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PAS 62137-3 © IEC:2008(E) – 9 –
3.6
cyclic bending strength for SMD
number of bending to the break of soldered joints of SMDs to the copper lands on board which
is fixed to a jig when the board is bent convex toward to the mounted SMDs
3.7
mechanical shear fatigue strength for SMD
imposition of cyclic shear deformation on the solder joints by mechanical displacement instead
of relative displacement generated by CTE (coefficient of thermal expansion) mismatch in
thermal cycling testing
NOTE The mechanical shear fatigue tests continues until the maximum force decreases to a certain value, which
corresponds to the appearance of an initial crack, or the electrical resistance-measuring instrument can detect electric
continuity interruption, and the number of cycles is recorded as fatigue life
3.8
cyclic drop test for SMD
number of drops to the break of soldered joints of an SMD to the copper lands on a board which
is fixed to a jig when the board is dropped from a specified height
3.9
cyclic steel ball drop strength for SMD
number of drops to the break of soldered joints of an SMD to the copper lands on a board when
the steel ball is dropped from a specified height on a board
3.10
pull strength for lead terminal type device
maximum applied force to break the soldered joint of a lead of an SMD to a land on board when
the lead is pulled using a jig
3.11
creep test for lead terminal type device
strength of a soldered joint expressed by the time to break the joint held in a thermostat when a
continuous force is applied to a lead of an SMD soldered to a land
3.12
fillet lifting phenomenon
phenomenon a solder fillet of a lead of an SMD is fillet lifting from a land on a board, or of the
land from the board (De-lamination)
3.13
daisy chain
all chain of connections solder joint are connected in series
NOTE Lands on both sides of a board and leads are solder- connected in a chain in the case of a lift off test
4 Procedure of selecting the applicable test method
4.1 Stress to solder joints in the field and test methods
The correlations between the test methods and the actual stress induced to components are
shown in Figure 1. The printed wiring board and the shapes of terminals effective to correlate
the test results to actual conditions of the component mounting in the filed are also shown as
reference. The selection of a test method suitable for a specific shape of terminal is given in 4.2.

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– 10 – PAS 62137-3 © IEC:2008(E)

Table 1 – Correlations between test methods and actual stresses in the filed
Test method Accelerated Applicable board/ Stress in the field and
stress applicable products
(Applicable standard) Components
application
a), b)
Conduction test
Temperature SMD Repeated thermal stress caused
cycling by the difference in thermal
IEC 62137:Annex B
a) expansion coefficients of
Pull strength (rapid
SMD
component and board at the
temperature
IEC 62137-1-1
(Gull-wing)
c) ON/OFF of equipment and/or
change)
a)
temperature changes in the
Shear strength
SMD
surrounding environment
IEC 62137-1-2
a)
Torque shear strength
SMD
Annex C
a)
Monotonic bending test SMD
Annex D
Cyclic bending strength test
Repeated board SMD Repeated mechanical stress
bending applied to soldered joints and
IEC 62137-1-4
board as in the case of keying,
especially for portable equipment
Mechanical shear fatigue test
Cyclic strain  SMD Repeated thermal stress caused
by the difference in thermal
IEC 62137-1-5
expansion coefficients of
component and board at the
ON/OFF of equipment and/or
temperature changes in the
surrounding environment
d)
Cyclic drop test
Repeated board SMD Shock induced to soldered joints
drop when equipment is erratically
IEC 62137-1-3
d) dropped while the equipment is in
Cyclic steel ball drop strength test Repeated ball drop SMD
use
Annex E
Pull strength test
Temperature Single-sided Repeated thermal stress caused
cycling TH/Leaded by the difference in thermal
Annex F
insertion type expansion coefficients of
(rapid
component and board at the
temperature
c) ON/OFF of equipment and/or
change)
temperature changes in the
surrounding environment
Creep strength test
Loading + Single-sided Degradation of soldered joint
Temperature TH/Leaded when a continuous force is
Annex G
insertion type applied
Observe of fillet lifting phenomenon Evaluation method Single-sided The external observation method
TH/Leaded insertion of fillet lifting phenomenon that
Annex H
type may occur when soldering an
alloy and the terminal plating
NOTE 1
a)
 This is a test to evaluate degradation of joint strength with repeated thermal stress induced to the joint by
means of rapid temperature change for an accelerated test. A proper test should be selected according to
the features of the component under test such as the shape of its leads.
b)
 This is a test to check if there is a failure at a soldered joint by measuring changes of resistance of the joint
without applying mechanical stress. This test method is not a new test method developed in this document
but referred here as an alternative method as it is a useful test especially for BGA and LGA.
c)
 Each temperature test is applied in the case of the following alloys.
1) temperature cycling test (Rapid temperature change): Sn-Ag-Cu, Sn-Zn, Sn-Bi and Sn-In
2) High temperature / high humidity test: Sn-Zn
3) High temperature test: Sn-Bi
d)
 Applicable using Sn-Ag-Cu, Sn-Zn, Sn-Bi and Sn-In all
...