IEC 60068-2-69:2007

IEC 60068-2-69
Edition 2.0 2007-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-69: Tests – Test Te: Solderability testing of electronic components for
surface mounting devices (SMD) by the wetting balance method

Essais d’environnement –
Partie 2-69: Essais – Essai Te: Essai de brasabilité des composants
électroniques pour les composants de montage en surface (CMS) par la
méthode de la balance de mouillage

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IEC 60068-2-69
Edition 2.0 2007-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-69: Tests – Test Te: Solderability testing of electronic components for
surface mounting devices (SMD) by the wetting balance method

Essais d’environnement –
Partie 2-69: Essais – Essai Te: Essai de brasabilité des composants
électroniques pour les composants de montage en surface (CMS) par la méthode
de la balance de mouillage
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
T
CODE PRIX
ICS 19.040; 31.190 ISBN 2 2-8318-9717-3

– 2 – 60068-2-69 © IEC:2007
CONTENTS
FOREWORD.3
1 Scope.5
2 Normative references .5
3 Terms and definitions .5
4 General description of the method .6
5 Description of the test apparatus .6
6 Preconditioning .6
6.1 Preparation of specimens .6
6.2 Ageing.7
7 Materials .7
7.1 Solder .7
7.2 Flux.8
8 Procedures.8
8.1 Test temperature.8
8.2 Solder bath wetting balance procedure.8
8.3 Solder globule wetting balance procedure .11
9 Presentation of results.14
9.1 Form of force versus time trace .14
9.2 Test requirements .15
10 Information to be given in the relevant specification .15
Annex A (normative) Equipment specification .16
Annex B (informative) Use of the wetting balance for SMD solderability testing .18
Bibliography.25

Figure 1 – Test apparatus.6
Figure 2 – Typical wetting balance trace .14

Table 1 – Recommended solder bath wetting balance test conditions .10
Table 2 – Time sequence of the test (solder bath) .11
Table 3 – Recommended solder globule wetting balance test conditions.12
Table 4 – Time sequence of the test (Solder globule) .13

60068-2-69 © IEC:2007 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ENVIRONMENTAL TESTING –
Part 2-69: Tests –
Test Te: Solderability testing of electronic
components for surface mounting devices (SMD)
by the wetting balance method
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
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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
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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 60068-2-69 has been prepared by IEC technical committee 91:
Electronics assembly technology.
This second edition cancels and replaces the first edition published in 1995 and constitutes a
technical revision. The main changes from the previous edition are as follows:
– Inclusion of lead-free alloy test conditions;
– Inclusion of new fluxes for testing, reflecting development of fluxes that have happened in
the industry in the past 20 years;
– Inclusion of new component types, and updating test parameters for the whole component
list.
– 4 – 60068-2-69 © IEC:2007
This bilingual version, published in 2008-04, corresponds to the English version.
The text of this standard is based on the following documents:
FDIS Report on voting
91/648/FDIS 91/680/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 the parts in the IEC 60068 series, under the general title Environmental testing,
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.
60068-2-69 © IEC:2007 – 5 –
ENVIRONMENTAL TESTING –
Part 2-69: Tests –
Test Te: Solderability testing of electronic
components for surface mounting devices (SMD)
by the wetting balance method
1 Scope
This part of IEC 60068 outlines test Te, solder bath wetting balance method and solder
globule wetting balance method, applicable for surface mounting devices. These methods
determine quantitatively the solderability of terminations on surface mounting devices.
IEC 60068-2-54 is also available for surface mounting devices and should be consulted if
applicable.
The procedures describe the solder bath wetting balance method and the solder globule
wetting balance method and are both applicable to components with metallic terminations and
metallized solder pads.
This standard provides the standard procedures for solder alloys containing lead (Pb) and for
lead-free solder alloys.
2 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 60068-1, Environmental testing – Part 1: General and guidance
IEC 60068-2-20:1979, Basic environmental testing procedures – Part 2: Tests – Test T:
Soldering
Amendment 2 (1987 )
IEC 60068-2-54:2006, Environmental testing – Part 2-54: Tests – Test Ta: Solderability
testing of electronic components by the wetting balance method
IEC 61190-1-3:2002, Attachment materials for electronic assemblies – Part 1-3: Requirements
for electronic grade solder alloys and fluxed/non-fluxed solid solder for electronic soldering
applications
ISO 683 (all parts), Heat-treatable steels, alloy steels and free-cutting steels
ISO 6362 (all parts), Wrought aluminium and aluminium alloy extruded rods/bars, tubes and
profiles
3 Terms and definitions
For the purpose of this document, the terms and definitions as defined in IEC 60068-1 and
IEC 60068-2-20 apply.
– 6 – 60068-2-69 © IEC:2007
4 General description of the method
After applying the liquid flux to the component termination and mounting the component in a
suitable holder, the specimen is suspended from a sensitive balance. The component
termination is brought into contact with the cleaned surface of a solder bath or the apex of a
solder globule, and immersed to the prescribed depth.
The resultant forces of buoyancy and surface tension acting upon the immersed termination
are detected by a transducer and converted to a signal which is continuously monitored as a
function of time, and recorded on a high speed chart recorder or displayed on a computer
screen.
The wetting speed and the extent of wetting are derived from the force against time curve.
5 Description of the test apparatus
A diagram showing a suitable arrangement for the test apparatus is shown in Figure 1. The
specimen is suspended from a sensitive balance and a mechanism used to either raise the
solder to meet the specimen or lower the specimen into the solder.
After conditioning, the transducer signal is passed to either a chart recorder or a computer,
where the force against time curve may be displayed and analysed.

Balance or
Signal
Computer or chart recorder
transducer
conditioner
Specimen
Globule block
or solder bath
Control box
Lift mechanism
IEC  602/07
Figure 1 – Test apparatus
Any other system capable of measuring the vertical forces acting on a specimen is admissible,
providing that the system has the characteristics given in A.1, and the solder bath and globule
support block meet the requirements of A.2 and A.3 respectively.
6 Preconditioning
6.1 Preparation of specimens
Unless otherwise specified, the specimen shall be tested in the as-received condition and
care should be taken to ensure that no part of the surface to be tested becomes contaminated,
particularly by contact with the fingers, during the preparation and handling of the specimen.

60068-2-69 © IEC:2007 – 7 –
If required by the component specification, the specimen may be cleaned by immersion in a
neutral organic solvent at room temperature. The specimen should be allowed to dry in air
before testing. No other cleaning is permitted.
6.2 Ageing
If required by the component specification, the component may be subjected to accelerated
ageing before testing. Ageing shall be performed in accordance with one of the following
conditions:
– ageing 1a of IEC 60068-2-20, Subclause 4.5.1;
– ageing 1b of IEC 60068-2-20, Subclause 4.5.1;
– ageing 3 of IEC 60068-2-20, Subclause 4.5.3;
– ageing according to method 1 of IEC 60068-2-20, but for 8 h.
7 Materials
7.1 Solder
7.1.1 General
The solder to be used for both the solder bath and for the solder globule wetting balance test
shall be as specified in 7.1.2 and 7.1.3.
7.1.2 Solder alloy containing lead
The solder shall be Sn60Pb40A, Sn63Pb37A or Sn62Pb36Ag02B (Refer to IEC 61190-1-3
alloy name).
NOTE The presence of silver in the solder reduces the dissolution effect on silver containing metallization on
components and therefore should be used when required by the relevant component specification.
7.1.3 Lead-free solder alloy
The preferred alloy composition to be used should consist of either 3,0 wt% Ag, 0,5 wt% Cu,
96,5 wt% Sn (Sn96,5Ag3Cu,5) or 0,7 wt% Cu, 99,3 wt% Sn (Sn99,3Cu,7). (Refer to
IEC 61190-1-3 for alloy name.)
NOTE A solder alloy consisting of 3,0 wt% to 4,0 wt% Ag, 0,5 wt% to 1,0 wt% Cu and the remainder of Sn may
also be used instead of Sn96,5Ag3Cu,5. The solder alloys consist of 0,45 wt% to 0,9 wt% Cu and the remainder of
Sn may be used instead of Sn99,3Cu,7.
7.1.4 Solder mass for solder globule wetting balance method
For the solder globule wetting balance method, the solder shall be in the form of pellets or cut
wire with a mass of 200 mg ± 10 mg for use on the 4 mm diameter pin globule support
block,100 mg ± 10 mg for use on 3,2 mm diameter pin support block or 25 mg ± 2,5 mg for
use on the 2 mm diameter pin globule support block.
Pellet mass
Pin diameter Pellet mass
tolerance
mm mg
mg
2 25
±2,5
3,2 100 ±10
4 200 ±10
– 8 – 60068-2-69 © IEC:2007
7.2 Flux
7.2.1 General
The flux used for the test shall be either rosin based or carboxylic acid based. The rosin
based flux is either non-activated or activated. The carboxylic acid based flux is either water
solution or alcohol solution.
Information about the used flux type shall be specified in the relevant specification.
7.2.2 Rosin based flux
a) Non-activated: consist of 25 wt% colophony in 75 wt% of 2-propanol (isopropanol) or of
ethyl alcohol (as specified in Appendix C of IEC 60068-2-20).
b) Activated flux: the activated flux which is above flux with the addition of diethylammonium
chloride (analytical reagent grade), up to amount of 0,2 % or 0,5 % chloride (expressed as
free chlorine based on the colophony content).
7.2.3 Carboxylic acid based flux
a) Water solution: consist of 90,1 % De-ionised Water, 5,0 % Glycol Ester (CAS
No. 34590-94-8) 1,6 % Adipic Acid, 1,6 % Succinic Acid, 1,6 % Glutaric Acid and 0,1 %
alcohol ethoxylate surfactant (CAS no 68131-39–5).
b) Alcohol solution: consist of 94 % Propan-2-ol, 1,5 % Adipic Acid, 1,5 % Succinic Acid,
1,5 % Glutaric Acid and 1,5 % Rosin.
NOTE These fluxes reflect modern flux formulations and have similar discriminating powers to the rosin test
fluxes.
8 Procedures
8.1 Test temperature
8.1.1 Solder alloy containing lead
Solder temperature prior to test and during test shall be 235 °C ± 3 °C.
8.1.2 Lead-free solder alloy
Unless otherwise specified in the relevant specification, the temperature of the solder prior to
the test shall be 245 °C ± 3 °C for Sn96,5Ag3Cu,5 solder and 250 °C ± 3 °C for Sn99,3Cu,7
solder.
8.2 Solder bath wetting balance procedure
The specimen is mounted in a suitable holder to give the desired dipping angle and the
termination(s) is/are centred above the solder bath. Preferred dipping angles are given in Table 1.
The temperature of the solder prior to the test shall be as described in 8.1.
Prior to testing, a continuous layer of the appropriate flux is applied to the portion of the
component termination to be tested, using a cocktail stick, cotton bud or similar applicator,
and excess flux droplets are removed by touching against absorbent paper. It is very
important that excess flux is not allowed to enter the specimen holder or remain on the
component. The presence of excess flux will cause explosive boiling as the flux solvent
makes contact with the molten solder.

60068-2-69 © IEC:2007 – 9 –
Immediately prior to testing, wipe the oxide from the solder surface with a non-wettable blade.
If required, the apparatus suspension and chart recorder are adjusted to the zero position.
Hang the specimen on the apparatus so that the lower edge of the component is 20 mm ± 5 mm
above the solder surface during the preheat period and allow the specimen to preheat/dry for 30 s
± 15 s prior to immersion in the solder. This period is required to remove the solvent from the
flux prior to the test and to prevent explosive boiling when the solder, specimen and flux come
into contact.
After preheating, the specimen and solder are brought into contact at a speed between
1 mm/s and 5 mm/s. The recommended immersion depth into the solder of the surface to be
tested shall be as specified in Table 1.

– 10 – 60068-2-69 © IEC:2007
Table 1 – Recommended solder bath wetting balance test conditions
a
Component Dipping angle Figure reference Immersion depth
mm
b
Capacitors 1608 (0603)
b
2012 (0805) Horizontal, Vertical
1A,1B, 1C
b
3216 (1206)  or 20° to 45°
b
4532 (1812)
b
Resistors 1608 (0603)
Horizontal, Vertical 1A, 1B,1C,
b
2012 (0805)
d d
b or 20° to 45° 1G ,1H
3216 (1206)
SOT 23
SOT 89
SOT 223
0,04 to 0,10
c
SOIC 16
c
1D, 1E, 1F
SOIC 28
Leaded SMD Vertical or 20° to 45°
c
VSO 40
c
QFP 48
c
QFP 160
c
PLCC 44
c
PLCC 84
Cylindrical SMD Horizontal, Vertical
1A,1B, 1C
or 20° to 45°
SOD 80 Vertical or 20° to 45° 1B, 1C
Not recommended for sizes below 1608 (0603).
The recommended dwell time is 5 s, except for SOT 89 and SOT 223 components, where 10 s is recommended.
The recommended immersion speed for all components is between 1 mm/s and 5 mm/s.
a
Orientation of the specimen terminals or leads towards the solder surface.
b
Component names in parentheses, dimensions are expressed in Imperial.
c
These leads may be cut and tested individually, but care should be taken not to deform the part of the lead to
be tested. This operation should be performed after ageing, if any ageing procedure is applied.
d
Figures 1G and 1H are applicable to the components which do not have electrode toward the solder surface
when Figure 1B is applied.
1A 1B 1C  1G
d
Horizontal Vertical 20°to 45° Vertical
1D 1E 1F 1H
d
20° to 45° Vertical 20° to 45° 20° to 45°
IEC  603/07
60068-2-69 © IEC:2007 – 11 –
The solder and specimen are held in this position for not less than 5 s and then separated.
The withdrawal rate is not specified as the force curve is not analysed once the specimen
starts to separate from the solder.
Time sequence of the test is shown in Table 2. The test sequence should be made in the
minimum time whilst maintaining repeatability.
Table 2 – Time sequence of the test (solder bath)
Procedure Time Duration
1) Fluxing 0 s 5 s
2) Hang the specimen on the apparatus ~15 s --
3) Wipe the oxide from the solder surface ~20 s --
4) Preheat ~30 s
30 s ± 15 s
5) Start ~75 s 3 s to 25 s
6) Solder immersion 100 s max. 5 s

The vertical force acting on the specimen is recorded during the period of contact between the
solder and the specimen. The force during withdrawal need not be recorded as the withdrawal
part of the curve is not analysed.
Once the specimen has cooled, the flux residues are washed from the specimen, using a
neutral organic solvent. The specimen is visually examined using a magnification of 10 ×.
Special attention should be paid to de-wetting, as de-wetting does not often occur until the
specimen is withdrawn from the solder.
Note that de-wetting may be obscured by the presence of solder icicles frozen onto the
termination as it is withdrawn from the solder.
8.3 Solder globule wetting balance procedure
Select the appropriate globule block for the component to be tested. Recommended globule
support block pin sizes are given in Table 3.
Set the temperature of the solder as specified in 8.1. Note that the globule blocks should
never be heated without solder covering the iron pin. Heating the uncovered pin could cause
the iron to become oxidized and difficult to wet.
The specimen is mounted in the appropriate holder, to give the desired dipping angle, and the
termination to be tested is centred above the solder globule. Recommended dipping angles
and immersion depths for a typical range of components are given in Table 3.
Prior to testing, a continuous layer of the appropriate flux is applied to the portion of the
component termination to be tested, using a cocktail stick, cotton bud or similar applicator and
excess flux droplets are removed by touching against absorbent paper. It is very important
that excess flux is not allowed to enter the specimen holder or remain on the component. The
presence of excess flux will cause explosive boiling as the flux solvent makes contact with the
molten solder.
Immediately before the test, the solder from the previous test should be removed, by wiping
the globule block with a cotton bud, and replaced with a new pellet of the appropriate mass.
Sufficient activated rosin flux (0,5 % halide, as specified in 7.2) shall be applied to the solder
globule. This maintains a clean surface for the duration of the test, and ensures that the iron
pin is fully wetted and the solder formed into a regular hemispherical shape. If required the
apparatus suspension and recording device are adjusted to the zero position.
Hang the specimen on the apparatus so that the lower edge of the component is 20 mm ± 5 mm
above the solder globule and allow the specimen to preheat/dry for 30 s ± 15 s prior to
immersion into the solder globule. This period is required to remove the solvent from the flux
prior to the test and to prevent explosive boiling when the specimen and solder come into
contact.
– 12 – 60068-2-69 © IEC:2007
After preheating, the specimen and solder are brought into contact at a speed between
1 mm/s and 5 mm/s. The immersion depth of the surface to be tested into the solder shall be
as specified in Table 3, which gives immersion depths for a typical range of components.
Table 3 – Recommended solder globule wetting balance test conditions
a
Component Dipping Figure Immersion Pin size Globule Remarks
b
angle depth  weight
mm mm mg
1005 (0402)
Horizontal
2A, 2B 2 25
or Vertical
1608 (0603)
Capacitors 0,10
2012 (0805) 3,2 or 4 100 or 200
Horizontal 2A
3216 (1206) 4 200
1005 (0402) Vertical 2B
2 25
1608 (0603)
Resistors 0,10
Horizontal
c
2012 (0805) 3,2 or 4 100 or 200
2A, 2H
or Vertical
3216 (1206) 4 200
Tantalum
Case sizes
c
capacitors, d Vertical 2H 0,10 4 200
A ,B,C,D
LEDs
SOT 23, 25,
26, 323, 343, 2D 0,10 2 25
353, 363
SOT 89, 0,20
1 outer pin only
SOT 223,
523 20 - 45 2F
Leaded
0,25
e
SMD
Gull wing
diode 4 200
Any SOIC
Remove sufficient
VSO 2D 0,20
leads to avoid
QFP, SOP
bridging between
tested leads
PLCC, SOJ Horizontal 2E 0,10
c
QFN Horizontal 2H 0,10 2 25 Caution from
bridging
Cylindrical SMD Horizontal 2A , 2B 0,25 4 200
or Vertical
SOD 80 Vertical 2B 0,20 4 200
Only peripheral
balls can be
f
Any BGA,CSP or LGA Horizontal 2G 0,10 2 25 tested, and only
test down to
1,0 mm pitch
Not recommended for sizes below 1005 (0402).
Bath method is preferred for capacitors 3216 (1206) size.
The recommended dwell time is 5 s, except for SOT 89 and SOT 223 components where 10 s is recommended.
For Figure 2B, rightward offset may be used. Rightward offset distance from the crest of the solder globule shall be
0 % to 15 % of the pin diameter and shall avoid leftward offset.
a
Component names in parentheses, dimensions are expressed in Imperial.
b
Orientation of the specimen terminals or leads towards the solder surface.
c
Figure 2H is applicable to the components which do not have electrode toward the solder surface when Figure 2B is
applied.
d
This test may only be applicable with certain test equipment.
e
These leads may be cut and tested individually, but care should be taken not to deform the part of the lead to be tested.

This operation should be performed after ageing, if any ageing procedure is applied.
f
This test is recommended only for those balls and bumps that will not melt at the respective temperature and are not
designed to melt during reflow operation.

60068-2-69 © IEC:2007 – 13 –
Table 3 (continued)
2A 2B 2C 2D
Horizontal Vertical 20° to 45° 20° to 45°
2E 2H
2F 2G
Horizontal Vertical
20° to 45°
IEC  604/07
The solder and specimen are held in this position for not less than 5 s and then separated.
The withdrawal rate is not specified as the force curve is not analysed once the specimen
starts to separate from the solder.
Time sequence of the test is shown in Table 4. The test sequence should be made in the
minimum of time whilst maintaining repeatability.
Table 4 – Time sequence of the test (Solder globule)
Procedure Time Duration
1) Fluxing 0 s 5 s
2) Hang the specimen on the apparatus ~15 s --
3) Wipe the oxide from the solder surface ~20 s --
4) Apply flux to solder globule ~30 s
5) Preheat ~40 s
30 s ± 15 s
6) Start ~85 s 3 s to 25 s
7) Solder immersion 110 s max. 5 s

The vertical force acting on the specimen is recorded during the period of contact between the
specimen and solder. The force during withdrawal need not be recorded as the withdrawal
part of the curve is not analysed.
The flux residues are washed from the specimen, once the specimen has cooled, using a
neutral organic solvent. The specimen is visually examined using a magnification of 10 ×.
Special attention should be paid to de-wetting, as de-wetting does not often occur until the
specimen is withdrawn from the solder.
Note that de-wetting may be obscured by the presence of solder icicles frozen onto the
termination as it is withdrawn from the solder.

– 14 – 60068-2-69 © IEC:2007
9 Presentation of results
9.1 Form of force versus time trace
The trace may be recorded in two forms, the only difference being the polarity of the force
readings. In this standard, forces acting upwards on the specimen (non-wetting) are shown as
negative and forces acting downwards on the specimen (wetting) are shown as positive.
A typical wetting balance trace is shown in Figure 2.
+Ve
D
E
C
F : Maximum wetting force
max
2/3 of F
max
t
Time
B
Buoyancy line
A
–Ve
IEC  605/07
Figure 2 – Typical wetting balance trace
Time t is the time at which the solder surface and the specimen first make contact, as
indicated by a small downward movement of the trace from the zero line.
At point A the solder meniscus starts to rise up the specimen termination. This is normally
characterized by a significant increase in the wetting force.
At point B the contact angle is 90°. A typical wetting balance trace is shown in Figure 2. The
measured force is that due to the buoyancy of the component.
At point C the wetting force reaches 2/3 of the maximum value of the resultant wetting force
and the wetting force shall exceed a specified value within a specified time.
At point D the maximum value of the resultant wetting force is reached during the specified
immersion period.
Point E is the force reading at the end of the specified test period.
Interpretation of the trace after E, during the withdrawal of the specimen, is not considered.
The wetting force in Figure 2 may be measured from the zero line, the buoyancy line, or the
minimum forces at point A (the force excursion).
NOTE Certain components may wet so easily that there may be no downward movement of the trace from the
zero line. This represents good solderability.

Force
60068-2-69 © IEC:2007 – 15 –
9.2 Test requirements
The requirements for the solderability of the components shall be expressed in terms of one
or more of the following parameters:
a) For the onset of wetting
A maximum value for the time interval (t to B )
b) For the progress of wetting
A maximum value of the time interval (t to C )
c) For the stability of wetting
force at E
A minimum value for the ratio:
force at D
10 Information to be given in the relevant specification
Clause and
subclause
a) Whether the specimen is to be cleaned prior to testing 6.1
b) Whether accelerated ageing is to be carried out and, if so,
by which method 6.2
c) Type of flux to be used 7.2
d) Composition of the solder 7.1
e) Globule size to be used 8.3
f) Test temperature, if other than specified 8.1
g) Portion of the specimen to be tested,
if other component than in Table 1 or Table 3 8.2, 8.3
h) Dipping position and angle if other component than in Table 1 or Table 3 8.2, 8.3
i) Immersion depth,
if other component than in Table 1 or Table 3 8.2, 8.3
j) Duration of the test, if other than 5 s 8.2, 8.3
k) Acceptance value for the onset and progress of wetting 9.2
l) Areas to be examined for wetting and dewetting 8.2, 8.3

– 16 – 60068-2-69 © IEC:2007
Annex A
(normative)
Equipment specification
A.1 Characteristics of the apparatus
For the purpose of this standard the complete apparatus, including the chart recorder or the
computer system, is to be considered as a single piece of equipment having the following
characteristics.
A.1.1 The response time of the recording device shall be such that return to centre zero on
removal of the maximum load shall be accomplished within 0,3 s, with an overshoot not
exceeding 1 % of the corresponding maximum reading.
A.1.2 The instrument may have a number of sensitivity settings. On the most sensitive
setting, it shall be capable of resolving a force of less than 0,02 mN.
A.1.3 The deflection of the recording device shall be directly proportional to the force
applied over the entire range to an accuracy better than ±5 % of the full-scale deflection.
A.1.4 Electrical and mechanical noise on the force trace shall not exceed 10 % of the signal
level, on the most sensitive range.
A.1.5 The stiffness of the spring system of a mechanical balance shall be such that a load of
10 mN causes a vertical displacement of the specimen suspension which does not exceed
0,1 mm.
A.1.6 If a chart recorder is used, the chart speed shall be not less than 10 mm/s.
A.1.7 The speed of immersion and withdrawal shall be between 1 mm/s and 5 mm/s.
A.1.8 The immersion depth shall be adjustable to an accuracy of ± 0,01 mm.
A.1.9 The solder temperature shall be maintained at specified temperature in 8.1, but should
be adjustable between 200 °C and 260 °C.
A.1.10 The time at maximum immersion shall be adjustable from 0 s to 10 s.
A.2 Solder bath
A.2.1 The bath shall be of sufficient thermal mass to enable the test temperature to be
maintained to the required precision. No part of the specimen shall be less than 15 mm from
the wall, so that the wetting forces are not affected by the curvature of the solder surface at
the edges of the bath. The depth of the bath shall not be less than 15 mm.
A.3 Globule support blocks
A.3.1 The body shall be made from a non-heat-treatable aluminium bar having a minimum
yield stress of 170 N/mm and having the following chemical composition:

60068-2-69 © IEC:2007 – 17 –
Magnesium 1,7 % to 2,8 %
Copper 0,1 % maximum
Silicon 0,6 % maximum
Iron 0,5 % maximum
Manganese 0,5 % maximum
Chromium 0,25 % maximum
Zinc 0,2 % maximum
Titanium or other grain refining elements 0,15 % maximum
Aluminium the remainder
See ISO 6362.
A.3.2 The 2 mm, 3,2 mm and 4 mm diameter iron pins shall be made of pure iron, or low
carbon steel having the following composition:
Carbon 0,05 % maximum
Oxygen 0,02 % maximum
Nitrogen 0,02 % maximum
–6
Other impurities 15 × 10
Iron the remainder
See ISO 683.
A.3.3 The mild steel pin shall be heat shrunk into a reamed hole in the aluminium body.
A.3.4 The aluminium body shall be heated by an electrical heater and the temperature
controlled by any means which will ensure a temperature within ± 3 °C of the specified
temperature in 8.1.
A.3.5 The temperature shall be measured by inserting a suitable probe, such as a
thermocouple, thermistor or platinum resistance wire, into a hole bored into the iron pin.
A.3.6 The top surface of the iron pin shall be tinned. After the completion of the test, the
globule support block shall be allowed to cool with a solder globule in position, to prevent
oxidation of the iron pin and subsequent dewetting.
A.3.7 The relative positions of the specimen and the solder globule shall be adjustable in
both horizontal axes.
– 18 – 60068-2-69 © IEC:2007
Annex B
(informative)
Use of the wetting balance for SMD solderability testing

B.1 Definition of the measure of solderability
The wetting balance method permits the measurement of the vertical force acting on a
specimen as a function of time, when the specimen is immersed in a bath of molten solder or
a molten solder globule. The solderability of the specimen is deduced from these observations
as the time to reach a given degree of wetting or as the degree of wetting reached within a
given time.
In general the construction of surface mounted devices does not allow the full meniscus rise
to develop, where the contact angle reduces to zero, and so the observed wetting force
cannot be compared to the theoretical wetting force, as defined in IEC 60068-2-54.
A specification for solderability may require that several points on the force-time curve
conform to particular values. This annex suggests points and values that may be used.
The test equipment shall conform to certain requirements if reproducible and quantitative
results are to be obtained; the requirements and methods of verifying that they are complied
with are also included in this annex.
The choice of method will depend upon the type of component to be tested and the level of
information required from the test. The relevant component specification will indicate which
method is preferred.
B.2 Solder globule mass and pin size
The solder globule wetting balance method is standardized using three sizes, 4 mm, 3,2 mm
and 2 mm diameter, for the iron insert in the aluminium block, and three corresponding solder
pellet sizes, 200 mg, 100 mg and 25 mg.
In general the smaller 25 mg solder pellet size gives improved discrimination with the smaller
SMD’s and facilitates testing of individual leads on fine pitch devices such as QFPs (Quad
Flat Pack) and BGAs (Ball Grid Array). The 200 mg globule is required for all larger SMD and
multi-leaded SMD, where the 25 mg solder globule has insufficient volume to completely
solder the terminations. The 100 mg globule provides larger wetting force than 200 mg
globule and larger thermal inertia than 25 mg globule. With the advent of even smaller SMD,
such as 0402 (0201), a smaller pin size, 1 mm diameter, and globule size 5 mg, are required
to match these finer SMD sizes.
A list of recommended pin sizes and globule weights is given in Table 3.
The solder globule used with the solder globule wetting balance method is a limited source of
heat and so will be able to discriminate between different thermal requirements on a
component. An extreme example of this is the SOT 89 and SOT 223 devices where the centre
lead has a much higher thermal requirement than the two outer leads.

60068-2-69 © IEC:2007 – 19 –
B.3 Specimen orientation and immersion depth
Surface mounted devices generally have short terminations and so it is advisable to use
shallow immersion depths to leave the largest area available above the solder, to develop the
largest possible wetting force. The buoyancy forces under these conditions will be relatively
small.
However, this should be balanced against the thermal needs of the component. The use of
very shallow immersion depths may give poor or unpredictable heat transfer into the
component, giving variable times before the onset of wetting. Too high immersion depths will
give poor wetting force readings. Table 1 gives a list of recommended immersion depths for a
range of common components, for the solder bath method, and Table 3 gives the
recommended immersion depths for the solder globule wetting balance method.
As a general guide where a termination can be presented as a straight vertical face, this will
provide the best results. However, it is also necessary to ensure that solder can flow along
the face that will eventually be soldered to the printed wiring board. The solder shall also be
brought into contact with the solderable coating, avoiding contact with unsolderable material,
including exposed cut ends. The immersion angle must also allow sufficient thermal contact to
provide adequate heat transfer into the component.
These requirements will have a different consequence for dipping orientation and dipping
depth, for different components.
B.3.1 Resistors and capacitors
Large capacitors can be immersed into the solder with the terminations horizontal, but
r
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