IEC 61189-5-301:2021

IEC 61189-5-301 ®
Edition 1.0 2021-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test methods for electrical materials, printed boards and other interconnection
structures and assemblies –
Part 5-301: General test methods for materials and assemblies – Soldering paste
using fine solder particles
Méthodes d’essai pour les matériaux électriques, les cartes imprimées et autres
structures d’interconnexion et ensembles –
Partie 5-301: Méthodes d’essai générales pour les matériaux et les
assemblages – Pâte à braser à fines particules de brasage

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IEC 61189-5-301 ®
Edition 1.0 2021-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test methods for electrical materials, printed boards and other interconnection

structures and assemblies –
Part 5-301: General test methods for materials and assemblies – Soldering

paste using fine solder particles

Méthodes d’essai pour les matériaux électriques, les cartes imprimées et autres

structures d’interconnexion et ensembles –

Partie 5-301: Méthodes d’essai générales pour les matériaux et les

assemblages – Pâte à braser à fines particules de brasage

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.180 ISBN 978-2-8322-9534-2

– 2 – IEC 61189-5-301:2021 © IEC 2021
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Powder particle size distribution measurement . 7
4.1 General . 7
4.2 Powder particle size distribution measurement – Scanning electron
microscope . 7
4.2.1 Object . 7
4.2.2 Equipment/apparatus . 7
4.2.3 Procedure . 7
4.2.4 Evaluation . 7
4.3 Powder particle size distribution measurement – Laser diffraction . 7
4.3.1 Object . 7
4.3.2 Equipment/apparatus . 7
4.3.3 Procedure . 7
4.3.4 Evaluation . 8
4.4 Powder particle size distribution measurement – Digital microscope . 8
4.4.1 Object . 8
4.4.2 Equipment/apparatus . 8
4.4.3 Procedure . 8
4.4.4 Evaluation . 8
5 Solder paste viscosity . 8
5.1 Method A:Trace spiral pump method . 8
5.1.1 Object . 8
5.1.2 Equipment/apparatus . 9
5.1.3 Procedure . 9
5.1.4 Evaluation . 10
5.2 Method B: Spiral pump method (IEC 61189-5-3, Test 5-3X06: Solder paste
viscosity – Spiral pump method (applicable to 300 Pa·s) . 10
5.2.1 Object . 10
5.2.2 Test specimen . 10
5.2.3 Equipment/apparatus . 10
5.2.4 Procedure . 10
5.2.5 Evaluation . 11
5.3 Additional information . 11
6 Printability test. 12
6.1 Object . 12
6.2 Equipment/apparatus . 12
6.3 Procedure . 14
6.4 Evaluation . 14
7 Slump test . 15
7.1 Object . 15
7.2 Equipment/apparatus . 15
7.3 Procedure . 15
7.4 Evaluation . 16
8 Reflow test . 16

8.1 Object . 16
8.2 Equipment/apparatus . 16
8.3 Procedure . 16
8.4 Evaluation . 17
9 High temperature observation test . 18
9.1 Object . 18
9.2 Equipment/apparatus . 18
9.3 Procedure . 20
9.4 Evaluation . 21
Annex A (informative)  Example of the test report on powder particle size distribution
measurement . 22
Annex B (informative) Example of the test report on viscosity characteristics . 23
Annex C (informative) Example of the test report on printability test . 24
C.1 Test report form . 24
C.2 Test report entry example . 25
Annex D (informative) Example of the test report on slump test . 26
Annex E (informative) Example of the test report on reflow test . 27
E.1 Test report form . 27
E.2 Test report entry example . 28
Annex F (informative) Example of the test report on high temperature observation test . 29
F.1 Test report form . 29
F.2 Melting property report form . 30
F.3 Entry example for melting property. 30
Annex G (informative) Example pictures of the printing and reflow test . 31
G.1 Printing test . 31
G.2 Reflow test . 32

Figure 1 – Metal mask for printability test . 13
Figure 2 – Test board with slits for splitting . 14
Figure 3 – Temperature profile for slump test . 16
Figure 4 – Temperature profile for reflow test. 17
Figure 5 – Metal mask for high temperature observation test . 19
Figure 6 – Example structure of high temperature observation apparatus . 20

Table 1 – QC procedure for Trace spiral-type viscometer . 9
Table 2 – QC procedure for spiral-type viscometer according to Test 5-3X06
in IEC 61189-5-3 . 11
Table 3 – Evaluation index for printability test . 15
Table 4 – Evaluation index for reflow test . 18

– 4 – IEC 61189-5-301:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHODS FOR ELECTRICAL MATERIALS, PRINTED BOARDS AND
OTHER INTERCONNECTION STRUCTURES AND ASSEMBLIES –

Part 5-301: General test methods for materials and assemblies –
Soldering paste using fine solder particles

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
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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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.
IEC 61189-5-301 has been prepared by IEC technical committee TC 91: Electronics assembly
technology. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
91/1655/CDV 91/1698/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 61189 series, published under the general title Test methods for
electrical materials, printed boards and other interconnection structures and assemblies, can
be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.

– 6 – IEC 61189-5-301:2021 © IEC 2021
TEST METHODS FOR ELECTRICAL MATERIALS, PRINTED BOARDS AND
OTHER INTERCONNECTION STRUCTURES AND ASSEMBLIES –

Part 5-301: General test methods for materials and assemblies –
Soldering paste using fine solder particles

1 Scope
This part of IEC 61189 specifies methods for testing the characteristics of soldering paste using
fine solder particles (hereinafter referred to as solder paste).
This document is applicable to the solder paste using fine solder particle such as type 6, type 7
specified in IEC 61190-1-2 or finer particle sizes.
This type of solder paste is used for connecting wiring and components in high-density printed
circuit boards which are used in electronic or communication equipment and such, equipping
fine wiring (e.g., minimum conductor widths and minimum conductor gaps of 60 µm or less).
Test methods for the characteristics of solder paste in this document are considering the effect
of surface activation force due to the fine sized solder particles which could affect the test result
by existing test methods.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 61189-5-3:2015, Test methods for electrical materials, printed boards and other
interconnection structures and assemblies – Part 5-3: General test methods for materials and
assemblies: Soldering paste for printed board assemblies
IEC 61190-1-2:2014, Attachment materials for electronic assembly – Part 1-2: Requirements
for soldering pastes for high-quality interconnects in electronics assembly
ISO 857-2, Welding and allied processes – Vocabulary – Part 2: Soldering and brazing
processes and related terms
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 857-2 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

3.1
digital microscope
microscope displaying an enlarged image on a screen of a personal computer or a monitor
4 Powder particle size distribution measurement
4.1 General
This measurement is for determining whether or not the solder particle used in the solder paste
complies with the relevant powder particle size type. Solder particle specimen shall be obtained
from the supplier or extracted from the solder paste according to 4.14.4 and 4.14.5 of
IEC 61189-5-3:2015.
4.2 Powder particle size distribution measurement – Scanning electron microscope
4.2.1 Object
The powder particle size distribution of the solder particle is measured using scanning electron
microscope (hereinafter, referred to as SEM).
4.2.2 Equipment/apparatus
SEM (Scanning Electron Microscope): 1 000 times or more magnification with image storage
device.
4.2.3 Procedure
At least 100 solder particles shall be observed using SEM. Observation may be done either
directly or using the acquired SEM image. The solder particle size shall be determined by
assumption that the solder particles are spherical. The solder particle shall be sorted out
according to the assigned classification type specified in Table 2 of IEC 61190-1-2:2014. The
number of sorted solder particle shall be counted and converted into masses.
4.2.4 Evaluation
Express the masses of the particle above, within, and below the nominal size range as
percentages of the mass of the original specimen. Enter the data in the test report. Annex A
shows an example of the test report.
4.3 Powder particle size distribution measurement – Laser diffraction
4.3.1 Object
The powder particle size distribution of the solder powder is measured using laser diffraction
type particle size distribution measuring apparatus.
4.3.2 Equipment/apparatus
a) laser diffraction type particle size distribution measuring apparatus;
b) balance: 0,01 g sensitivity;
c) spatula.
4.3.3 Procedure
Measurement shall be done in accordance with the instructions of the measuring apparatus.
Measure the blank sample to ensure the measuring apparatus is clean enough for measuring.
0,5 g to 10 g of solder powder shall be measured for the particle size distribution.

– 8 – IEC 61189-5-301:2021 © IEC 2021
4.3.4 Evaluation
Express the masses of the particle above, within, and below the nominal size range as
percentages of the mass of the original specimen. Enter the data in the test report. Annex A
shows an example of the test report.
4.4 Powder particle size distribution measurement – Digital microscope
4.4.1 Object
The powder particle size distribution of the solder powder is measured using a digital
microscope capable of three-dimensional (3D) observation by 3D construction of an acquired
image.
4.4.2 Equipment/apparatus
a) Glass slide
b) 3D digital microscope:
1) 1 000 times or more magnification;
2) equipping telecentric optical system and transmissive illumination which enable high-
precision measurement;
3) equipping an image storage device which is capable of 3D construction from the stored
images.
4.4.3 Procedure
Measurement shall be done in accordance with the instructions of the measuring apparatus. At
least 100 solder particles shall be placed on a glass slide, then observed using a digital
microscope. 3D image shall be stored.
The powder particle size shall be determined by assumption that the solder powders are
spherical. The powders shall be sorted out according to the assigned classification type
specified in Table 2 of IEC 61190-1-2:2014. The number of sorted particles shall be counted
and converted into masses.
4.4.4 Evaluation
Express the masses of the powder above, within, and below the nominal size range as
percentages of the mass of the original specimen. Enter the data in the test report. Annex A
shows an example of the test report form.
5 Solder paste viscosity
5.1 Method A:Trace spiral pump method
5.1.1 Object
This test specifies a standard procedure for determining viscosity-shear rate characteristics and
thixotropy (thixotropic index), which is also close relating to the printability of the solder paste.
Trace spiral viscometer is a coaxial-cylinder rotational type viscometer with a small sample
receptance, for example 0,2 cm capacity. Outer barrel of the viscometer is rotated to draw up
the solder paste specimen from the receptacle. After all of the solder paste is drawn up, the
outer cylinder is rotated in the opposite direction to return the solder paste into the receptacle.
This action is repeated, with the solder paste ascending and descending from the receptacle.
This subjects the solder paste to shear stresses, which is detected as a torque on the inner
barrel during the ascending period, and the viscosity characteristic being obtained from the
rotational speed of the cylinder. In addition, the thixotropic index is calculated from the viscosity

−1
characteristics. Shear rate is defined as D = v/y(s ) using rotational speed of the outer cylinder
(v) and the gap between inner barrel and outer cylinder (y).
The test may be performed in accordance with Test 5-3X06 in IEC 61189-5-3:2014 as test
method B.
5.1.2 Equipment/apparatus
a) spatula;
b) viscometer: trace spiral-type viscometer;
c) constant temperature chamber: either with the viscometer body built-in or external;
d) metal receptacle: 0,2 cm capacity for trace spiral-type viscometer;
e) recorder: personal computer, etc.;
f) solvent: propan-2-ol (reagent grade), ethyl alcohol (reagent grade), etc.
5.1.3 Procedure
See Table 1 for the test procedure.
a) If necessary, leave the solder paste at room temperature.
b) Stir with a spatula to homogenize the solder paste.
c) Put the solder paste into a metal receptacle.
d) Set the metal receptacle containing the solder paste into the micro spiral viscometer.
e) Rotate the outer cylinder to fill the solder paste between the inner barrel and the outer
cylinder; set the temperature of the constant temperature chamber to 25 °C±0.5 °C while the
outer cylinder is stationary and wait for approximately 10 minutes until the temperature of
the constant temperature chamber is stabilized.
f) After the temperature of the constant temperature chamber is stabilized, measure viscosity
at the rotational speed of 10 r /min ± 0,5 r /min for approximately 2 minutes.
g) Take out the metal receptacle, the inner barrel and the outer cylinder; clean them with
suitable reagent grade solvent such as propan-2-ol or ethyl alcohol; put a new solder paste
into the metal receptacle; set them again into a trace spiral viscometer.
h) Rotating the outer cylinder again; once the solder paste has filled the area between the
inner cylinder and the outer cylinder, set the temperature of the constant temperature
chamber to 25 °C ± 0,5 °C while the outer cylinder is stationary; wait for approximately
10 min until the temperature of the constant temperature chamber stabilizes.
i) Measure viscosity at the rotational speed of 5 r/min ± 0,25 r/min for approximately 4 min,
followed by 20 r/min ± 1,0 r/min for approximately 1 min; viscosity values at
5 r/min ± 0,25 r/min and 20 r /min ± 1,0 r/min shall be read.
Table 1 – QC procedure for Trace spiral-type viscometer
Speed Time
(r/min) (min)
10 2
Remove soldering paste and clean the inner barrel and
the outer cylinder. Then, fill fresh soldering paste into
a metal receptacle
5 4
20 1
– 10 – IEC 61189-5-301:2021 © IEC 2021
The thixotropy index (TI) is obtained from the following formula.
log(/ηη )
TI=
log(DD/ )
2 1
where
η is the viscosity (Pa·s) at shear rate D ;
1 1
η is the viscosity (Pa·s) at shear rate D ;
2 2
−1 −1
D is the shear rate 1 (s ), D = 3 (s ) at 5 r/min;
1 1
−1 −1
D is the shear rate 2 (s ), D = 12 (s ) at 20 r/min.
2 2
5.1.4 Evaluation
Annex B shows an example of the test report form. Enter the viscosity measured in 5.1.2 f) and
thixotropy index obtained in 5.1.3 i).
5.2 Method B: Spiral pump method (IEC 61189-5-3, Test 5-3X06: Solder paste
viscosity – Spiral pump method (applicable to 300 Pa·s)
5.2.1 Object
This test specifies a standard procedure for determining the viscosity of solder paste applicable
to 300 Pa·s.
5.2.2 Test specimen
The paste to be tested shall be stabilized at (25 ± 1) °C for a minimum of 24 h prior to testing.
The paste volume shall be sufficient to fill the viscometer receptacle to about 60 % of its depth.
5.2.3 Equipment/apparatus
The equipment used shall be a spiral pump viscometer. Set the instrument rotational speed for
10 r/min. Other equipment may be used provided the results can be empirically correlated as
mutually agreed upon. Additional shear rates may be specified by the user or the supplier.
5.2.4 Procedure
5.2.4.1 Preparation
a) Open the container(s), remove any internal cover, scrape off paste adhering to the lids or
internal cover(s) and the container wall(s) and add this to the paste in the container(s).
b) Using a spatula, stir the paste gently for 1 to 2 min to homogenize it, taking care to avoid
the introduction of air.
c) Transfer sufficient paste to the viscometer receptacle to fill this to about 60 % of its depth.
Place the receptacle in the temperature-controlled unit on the viscometer and allow it to
stabilize at (25 ± 0,25) °C for 15 min.
5.2.4.2 Test
See Table 2 for the test procedure.
a) Immerse the instrument sensor into the sample in accordance with the equipment
manufacturer's instructions. The solder paste shall not cover the pump outlet.
b) Turn on the chart recorder and set the instrument to run at one specific shear rate. Take a
reading when the output has been stable for at least 1 min.

Table 2 – QC procedure for spiral-type viscometer according to Test 5-3X06
in IEC 61189-5-3
Speed Time
(r/min) (min)
10 3
3 6
4 3
5 3
10 3
20 1
30 1
10 1
The thixotropy index (TI) is obtained from the following formula:
log(/ηη )
TI=
log(DD/ )
2 1
where
η is the viscosity (Pa·s) at shear rate D ;
1 1
η is the viscosity (Pa·s) at shear rate D ;
2 2
−1 −1
D is the shear rate 1 (s ), D =1.8 (s ) at 3 r/min;
1 1
−1 −1
D is the shear rate 2 (s ), D =18 (s ) at 30 r/min.
2 2
5.2.5 Evaluation
Record the data into the test report form.
5.3 Additional information
Test equipment sources: The equipment sources described below represent those currently
known to the industry. Users of this test method are urged to submit additional source names
as they become available, so that this list can be kept as up-to-date as possible.
Spiral pump viscometer equipment :
Brookfield Engineering Laboratories, Inc., 240 Cushing Street, Stoughton, MA 02072
(617) 344-4310;
Malcom Instruments Corp., 26226 Industrial Blvd., Hayward, CA 94545, (510) 293-0580,
(510) 293-0584.
___________
This information is given for the convenience of users of this document and does not constitute an endorsement
by IEC of the product named. Equivalent products may be used if they can be shown to lead to the same
results.
– 12 – IEC 61189-5-301:2021 © IEC 2021
6 Printability test
6.1 Object
This test specifies a standard procedure for determining printability of the solder paste.
The solder paste under evaluation is printed onto the copper-clad laminate board (hereinafter,
referred to as test board) using the printing pattern shown in Figure 1 for evaluating the
printability. The shape and dimensions of the printed solder paste are evaluated, at the
beginning of printing and at the time of continuous printing, and their stability. The planar shape
and thickness (distribution) of the printed solder pastes and their stability during continuous
printing are measured.
The printed solder paste on the board may be used for tests 7 through 9.
6.2 Equipment/apparatus
a) Metal mask:
1) (30 ± 5) μm thickness, made of additive nickel plate;
2) the hole opening pattern is as shown in Figure 1, straight holes without taper;
3) outer frame dimensions should be designed to meet the printing machine, for example,
650 mm × 550 mm for automatic printing machine.
b) Test board:
1) copper-clad laminate board, preferred dimensions are 92 mm (width) × 80 mm
(length) × 0,8 mm (thickness); copper foil thickness of approximately 12 µm; other
dimensions or copper foil thickness may be used in accordance with printing machine
requirement;
2) if necessary, alignment mark may be indicated;
3) if the printing for printability test and for the high-temperature observing test are
performed simultaneously then a test board having the arrangement shown in Figure 2
with split grooves for dividing substrates may be used.
c) Printing machine: capable of automatic printing with alignment mechanism;
d) Spatula;
e) 3D microscopes: 200 times or more magnification with image storage device;
f) Laser-type displacement gauges and non-contact shape-measuring devices: 0,1 µm or finer
resolution.
Key
G Pattern gap
Ø Opening hole diameter
a) Details of the metal mask opening (130 µm opening hole diameter – 60 µm gap)

Key
G Pattern gap in µm
Ø Opening hole diameter in µm
b) Metal mask opening array
Dimensions in millimetres
Key
A Example of 4 metal mask array (Figure 1 b)) arrangements, 90º rotation each other.
B Example of arranging 4 patterns for high temperature observation test (Refer to Figure 5).
c) Example of metal mask arrangement for printability test
Figure 1 – Metal mask for printability test

– 14 – IEC 61189-5-301:2021 © IEC 2021
Dimensions in millimetres
Key
C Slit for splitting
Figure 2 – Test board with slits for splitting
6.3 Procedure
a) If necessary, leave the solder paste at room temperature: (20 ± 5) °C.
b) Stir with a spatula to homogenize the solder paste.
c) The solder paste is put on a metal mask placed on a printing machine, and the solder paste
is printed on a test board using a squeegee. Printing temperature shall be controlled
between (20 ± 5) °C.
d) The planar shape (dimensions) of the printed solder paste shall be measured using captured
image by a 3D microscope. The thickness of the solder paste shall be measured using a
laser displacement meter or a non-contact shape measuring device.
6.4 Evaluation
The printed solder paste of the first and the tenth printing during continuous printing shall be
evaluated. Evaluation items are the presence or absence of bleeding, blurring and bridging
comparing the difference between the metal mask hole dimension and the shape of the printed
solder paste. Table 3 shows the evaluation index.
Annex C shows an example of the test report. Annex G (see Clause G.1) shows the example
pictures corresponding to Table 3.

Table 3 – Evaluation index for printability test
Evaluation index for
Description Image
printability
Printing defects such as bleeding,
blurring, bridging, and chipping are not

existing.
A Good
The printed solder paste does not greatly

differ from the shape and size of the
holes in the metal mask.
Solder paste spreads thinly around the
N Bleeding
bottom of adjacent printing units.

Printed solder paste forms icicle like
T Icicle
shape.
Missing or short Solder paste is partially missing or short
L
of solder amount of solder amount.

B Bridge Connecting adjacent printing units

Printed solder paste is thinner than the
K Grazing thickness of the metal mask (including
unprinted).
7 Slump test
7.1 Object
This test specifies a standard procedure for evaluating the degree of solder paste slump under
the preheating conditions in the reflow soldering.
7.2 Equipment/apparatus
a) metal mask: according to 6.2 a);
b) test board: according to 6.2 b);
c) printing machine: according to 6.2 c);
d) reflow furnace: capable to control the temperature profile specified in Figure 3; in the furnace,
nitrogen atmosphere controlling the oxygen concentration of 200 ppm or less;
e) magnifying equipment: microscope, etc.
7.3 Procedure
a) Printing shall be done according to 6.3 a) through c).
b) The printed test board shall be subjected to the temperature profile specified in Figure 3
using reflow furnace, under the atmospheric oxygen concentration of 200 ppm or less;
heating starts at room temperature; heating temperature shall be equal to or less than the
solidus temperature of the solder alloy used in the solder paste (ex. 130 °C to 180 °C for
Sn63Pb37 or Sn96,5Ag3Cu,5 solder alloy); ramp down rate for cooling is not specified.
c) After cooling, the solder paste on the test board shall be subjected to visual inspection using
magnifying equipment such as a microscope; for each printed solder paste diameter, identify
the minimum gap where no bridge occurs.

– 16 – IEC 61189-5-301:2021 © IEC 2021

Key
K Ramp up rate: 2 K/s to 3 K/s
a
T Heating temperature
a
t Heating duration: at least 120 s
a
Figure 3 – Temperature profile for slump test
7.4 Evaluation
Annex D shows an example of the test report.
8 Reflow test
8.1 Object
This test specifies a standard procedure for evaluating the reflow properties of the solder paste
under the reflow soldering conditions.
8.2 Equipment/apparatus
a) metal mask: according to 6.2 a);
b) test board: according to 6.2 b);
c) printing machine: according to 6.2 c);
d) reflow furnace: capable to control the temperature profile specified in Figure 4; in the furnace,
nitrogen atmosphere controlling the oxygen concentration of 200 ppm or less;
e) magnifying equipment: microscope, etc.
8.3 Procedure
a) Printing shall be done according to 6.3 a) through c).
b) Reflow shall be done within 8 h after printing.
c) The printed test board shall be subjected to the temperature profile specified in Figure 4
using reflow furnace, under the atmospheric oxygen concentration of 200 ppm or less;
heating starts at room temperature (15 °C to 35 °C); ramp down rate for cooling is not
specified.
Key
K Ramp up rate to pre-heating: 2 K/s to 3 K/s
a
T Pre-heating temperature range: 130 °C to 180 °C, not exceed the solidus temperature of the solder alloy.
p
t Pre-heating duration: 120 s to 200 s
p
K Ramp up rate to heating: 1 K/s to 2 K/s
a
T Heating temperature: (240 ± 3) °C for Sn96,5Ag3Cu,5 solder alloy, or (30 ± 3) °C above the liquidus temperature
b
of the solder alloy.
t Heating duration: 10 s or less
b
Figure 4 – Temperature profile for reflow test
d) After cooling, the solder paste on the test board shall be subjected to visual inspection using
magnifying equipment such as a microscope.
8.4 Evaluation
Table 4 shows the valuation index. Annex E shows an example of the test report.
Annex G (see Clause G.2) shows the example pictures corresponding to Table 4.

– 18 – IEC 61189-5-301:2021 © IEC 2021
Table 4 – Evaluation index for reflow test
Evaluation index
Description Reflow image
for reflow
No un-merged and de-wetting
are existing. The printed
1 No defect
solder paste wets over the
printed area.
Connecting adjacent reflowed
Bridge
2B units
Un-merged solder particles
Solder ball
2S around a big merged solder
No un-melted solder exists.
3 De-wetting But the de-wetting area
spreads.
Although un-melted solder
Partially particles exist, most of the
un-melted solder particles melted and
integrated.
Almost all the solder particles
5 Un-melted
are un-melted.
9 Hi
...