IEC 61189-11:2013

IEC 61189-11 ®
Edition 1.0 2013-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test methods for electrical materials, printed boards and other interconnection
structures and assemblies –
Part 11: Measurement of melting temperature or melting temperature ranges of
solder alloys
Méthodes d'essai pour les matériaux électriques, les cartes imprimées et autres
structures d'interconnexion et ensembles –
Partie 11: Mesure de la température de fusion ou des plages de températures de
fusion des alliages à braser
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IEC 61189-11 ®
Edition 1.0 2013-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test methods for electrical materials, printed boards and other interconnection

structures and assemblies –
Part 11: Measurement of melting temperature or melting temperature ranges of

solder alloys
Méthodes d'essai pour les matériaux électriques, les cartes imprimées et autres

structures d'interconnexion et ensembles –

Partie 11: Mesure de la température de fusion ou des plages de températures de

fusion des alliages à braser
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX P
ICS 31.180 ISBN 978-2-83220-800-7

– 2 – 61189-11 © IEC:2013
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Summary of measuring methods . 6
5 Test equipment . 6
5.1 Method A:DSC . 6
5.1.1 DSC . 6
5.1.2 Balance . 6
5.1.3 Pans . 6
5.1.4 Inert gas . 6
5.1.5 Alumina powder . 6
5.2 Method B:Cooling curve of molten solder . 7
5.2.1 Electric furnace . 7
5.2.2 Thermocouple. 7
5.2.3 Measuring instrument . 7
5.2.4 Recorder . 7
5.2.5 Container. 7
6 Calibration of the temperature . 7
7 Procedure for the measuring method . 7
7.1 Method A: DSC . 7
7.1.1 Test condition . 7
7.1.2 Procedure for measuring the DSC curve . 8
7.2 Method B: Cooling curve of molten solder . 10
7.2.1 Test condition . 10
7.2.2 Procedure for measuring the cooling curve of molten solder . 10
Annex A (normative) Test report on melting temperatures of solder alloys . 12
Annex B (informative) Examples of test result (Method A) . 13
Annex C (informative) Example of test result (Method B) . 14
Bibliography . 15

Figure 1 – Determination of solidus temperature . 8
Figure 2 – Determination of temperature of melting ends . 9
Figure 3 – Determination of liquidus temperature . 10
Figure 4 – Cooling curves of molten solder . 11
Figure B.1 – Example of test result (Method A: Sn96,5Ag3Cu,5 alloy) . 13
Figure B.2 – Example of test result (Method A: Sn95,8Ag3,5Cu,7 alloy). 13
Figure C.1 – Example of test result (Method B: Sn96,5Ag3Cu,5 alloy) . 14
Figure C.2 – Example of test result (Method B: Sn95,8Ag3,5Cu,7 alloy) . 14

Table 1 – Metal list for calibration . 7
Table A.1 – Report form . 12

61189-11 © IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHODS FOR ELECTRICAL MATERIALS,
PRINTED BOARDS AND OTHER INTERCONNECTION STRUCTURES
AND ASSEMBLIES –
Part 11: Measurement of melting temperature or
melting temperature ranges of solder alloys

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
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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 61189-11 has been prepared by IEC technical committee 91:
Electronics assembly technology.
The text of this standard is based on the following documents:
FDIS Report on voting
91/1086/FDIS 91/1097/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 61189-11 © IEC:2013
A list of all parts of IEC 61189 under the general title Test methods for electrical materials,
printed boards and other interconnection structures and assemblies can be found in the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC 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.
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.
61189-11 © IEC:2013 – 5 –
TEST METHODS FOR ELECTRICAL MATERIALS,
PRINTED BOARDS AND OTHER INTERCONNECTION STRUCTURES
AND ASSEMBLIES –
Part 11: Measurement of melting temperature or
melting temperature ranges of solder alloys

1 Scope
This part of IEC 61189 describes the measurement method of melting ranges of solder alloys
that are mainly used for wiring of electrical equipment, for electrical and communication
equipment, and for other apparatus, as well as for connecting components.
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 60194,— Printed board design, manufacture and assembly – Terms and definitions
IEC 61189-3, Test methods for electrical materials, printed boards and other interconnection
structures and assemblies – Part 3: Test methods for interconnection structures (printed
boards)
IEC 61190-1-3, Attachment materials for electronic assembly – Part 1-3: Requirements for
electronic grade solder alloys and fluxed and non-fluxed solid solders for electronic soldering
applications
ISO 9453, Soft solder alloys – Chemical compositions and forms
ISO 11357-1, Plastics – Differential scanning calorimetry (DSC) – Part 1: General principles
3 Terms and definitions
For the purposes of this document the terms and definitions of IEC 60194, IEC 61189-3,
IEC 61190-1-3, ISO 9453 and ISO 11357-1, as well as the following apply.
3.1
melting temperature ranges
total range of solidus and liquidus temperature of solder alloys
3.2
solidus temperature
temperature when solder alloys start to melt measured by DSC (method A)
———————
Sixth edition to be published.

– 6 – 61189-11 © IEC:2013
3.3
solidus temperature
temperature when solidification of solder alloys ends measured by the cooling curve of molten
solder (method B)
3.4
liquidus temperature
temperature when melting ends measured for various heating temperature levels by DSC
(method A)
3.5
liquidus temperature
solidification temperature measured by the cooling curve of molten solder (method B)
3.6
DSC curve
curve measured by differential scanning calorimetry (DSC)
4 Summary of measuring methods
The melting temperature range of solder alloys is measured by using the following methods.
Method A: Differential scanning calorimetry (DSC).
Method B: Cooling curve of molten solder.
Test report shall be made according to Annex A.
5 Test equipment
5.1 Method A: DSC
5.1.1 DSC
See ISO 11357-1.
5.1.2 Balance
The balance shall have a resolution of 0,1 mg or better.
5.1.3 Pans
Pans shall be constructed of a material with a high heat transfer rate and which is not
corroded by the samples. Usually, aluminium is used.
5.1.4 Inert gas
Inert gas (example N2 or Ar: of a purity higher than 99,9 %) should be used to avoid the
sample oxidation.
5.1.5 Alumina powder
Alumina powder should be used as a reference material. It is stable for the temperature range
of the measurement. See ISO 11357-1.

61189-11 © IEC:2013 – 7 –
5.2 Method B: Cooling curve of molten solder
5.2.1 Electric furnace
It shall be capable of heating its content to a temperature of 400 °C or higher and provide
good heat insulation.
5.2.2 Thermocouple
A thermocouple that is suitable for the temperature being used, shall be selected. The
compensating lead used shall be suitable for the thermocouple being used.
5.2.3 Measuring instrument
The heat flow measuring instrument shall be capable of measurements of one second
intervals or less.
5.2.4 Recorder
The recorder shall be capable of recording a cooling curve and reading in 0,1 °C units.
5.2.5 Container
The graphite or ceramic crucible shall be used.
6 Calibration of the temperature
Temperature calibration shall be conducted using the pure materials listed in Table 1, whose
purity shall be 99,99 % or higher. The melting points of two or more pure materials that are
close to the temperature to be measured, shall be measured under the same conditions as
those applied to the sample, and a compensation formula with a linear function shall be
determined for the temperature correction from the obtained measurements and the melting
temperatures given in Table 1.
Table 1 – Metal list for calibration
Metal Melting temperature
°C
In (indium) 156,6
Sn (tin) 231,9
Pb (lead) 327,4
7 Procedure for the measuring method
7.1 Method A: DSC
7.1.1 Test condition
7.1.1.1 Sample mass
The sample mass shall be from 5 mg to 50 mg.
7.1.1.2 Inert gas flow
Inert gas shall be used. Gas flow rate shall be from 10 ml/min to 50 ml/min.

– 8 – 61189-11 © IEC:2013
7.1.1.3 Heating rate
Heating rate shall be from 0,5 °C/min to 10 °C/min. Recommended heating rate are 0,5, 1, 2,
5 and 10 °C/min.
7.1.2 Procedure for measuring the DSC curve
7.1.2.1 Instructions
Carry out the measuring DSC curve as follows.
a) The sample is placed in the centre part of pans, and the cap of the pans is put and
clamped.
b) The pan containing the sample is placed on to the pan holder, and the pan with alumina
powder is placed on the other pan holder.
c) Flow the inert gas (example N2 or Ar) until the measurement ends.
d) Carry out the measuring DSC curve with a heating rate of 0,5 °C/min up to a temperature
about 30 °C higher than the heat flow peak.
Repeat procedures a) through d) using a new sample, except heating rate of 1, 2, 5 and
10 °C/min.
7.1.2.2 Solidus temperature
The data of a heating rate of 2 °C/min are used. A typical DSC curve is shown in Figure 1. T1
or T2 represent the solidus temperature.
a) If melting occurs abruptly, then the temperature when melting starts shall be the
temperature T1 at the intersection of the extrapolation of the low-temperature side
baseline towards the high-temperature side and the tangent drawn from the low-
temperature side endothermic peak at the point with the steepest slope, as shown in
Figure 1a. In this case, correct the temperature, using T1 of the pure materials.
b) If melting occurs gradually, then determine temperature T2 at the point at which the curve
starts to leave the baseline, as shown in Figure 1b. In this case, correct the temperature,
using T2 of the pure materials. Repeat the measurement several times and then determine
the average.
T2
T1
Temperature  (°C)
Temperature  (°C)
IEC  1070/13 IEC  1071/13
Figure 1a – Abruptly melting alloy Figure 1b – Gradually melting alloy
Figure 1 – Determination of solidus temperature
Heat flow
Heat flow
61189-11 © IEC:2013 – 9 –
7.1.2.3 Liquidus temperature
The data of a heating rate of 0,2, 0,5, 1, 2, 5 and 10 °C/min are used. A typical DSC curve is
shown in Figure 2. T3 or T4 indicate the temperature where melting ends.
a) If melting occurs with a single peak, the temperature of melting ends shall be the
temperature T3 at the intersection of the extrapolation of the high-temperature side
baseline towards the low-temperature side and the tangent drawn from the high-
temperature side endothermic peak at the point with the steepest slope, as shown in
Figure 2a.
b) If melting occurs with double or more peaks, the temperature where the melting ends shall
be the temperature T4 at the intersection of the extrapolation of the high-temperature side
baseline towards the low-temperature side and the tangent drawn from the most highest-
temperature side endothermic peak at the point with the steepest slope, as shown in
Figure 2b.
T3
Temperature  (°C)
Temperature  (°C)
IEC  1072/13 IEC  1073/13
Figure 2a – Single melting peak Figure 2b – Double or more melting peaks
Figure 2 – Determination of temperature of melting ends
c) The extrapolated end temperature of endothermic peak is a linear function of the square
root of the heating rate. Therefore, the point of interception on a temperature axis of the
linear function is assumed to be the liquidus temperature, as shown in Figure 3.
NOTE Examples of the test results are shown in Annex B.
Heat flow
Heat flow
– 10 – 61189-11 © IEC:2013
Liquidus temperature
0,5 –0,5
Square root of heating rate  (°C × min )
IEC  1074/13
Figure 3 – Determination of liquidus temperature
7.2 Method B: Cooling curve of molten solder
7.2.1 Test condition
7.2.1.1 Sample mass
The sample mass shall be 500 g or more.
7.2.1.2 Sample melting
Place the sample in the container and then heat it in the electric furnace until it melts.
7.2.1.3 Thermocouple installation
Position the temperature-measuring junction of the thermocouple in the centre of the molten
solder.
7.2.1.4 Reference junction
The reference junction shall be of the cryoscopic, thermoelectric cooling, or compensating
type.
7.2.2 Procedure for measuring the cooling curve of molten solder
7.2.2.1 Instructions
Melt the entire sample in the crucible, then turn off the power to the electric furnace and
measure the temperature as the sample cools down.
Typical cooling curves of molten solder are shown in Figure 4.
7.2.2.2 Solidus temperature
The solidus temperature shall be determined from the parallel portion, (T6, as shown in
Figure 4b). If undercooling occurs, as shown in Figure 4c, then the temperature T7 at the
intersection of the extrapolation of the parallel portion toward the short-time side and the
cooling curve shall be assumed to be the solidus temperature.
Extrapolated end temperature  (°C)

61189-11 © IEC:2013 – 11 –
7.2.2.3 Liquidus temperature
The liquidus temperature shall be determined from the inflection point (T5) of the cooling
curve (time-temperature curve), as shown in Figure 4a. If two or more inflection points or
parallel portions appear, then the first one shall be used to determine the liquidus temperature.
In some alloys, for example Sn95,5Ag3Cu,5 and Sn95,8Ag3,5Cu,7, liquidus temperature may
not be measured. Annex C shows such examples of cooling curve.

T5
T6
T7
Time
Time
Time
IEC  1075/13 IEC  1076/13 IEC  1077/13

Figure 4a – Inflection Figure 4b – Parallel Figure 4c – Undercooling
point appears portion appears occurs
Figure 4 – Cooling curves of molten solder
Temperature  (°C)
Temperature  (°C)
Temperature  (°C)
– 12 – 61189-11 © IEC:2013
Annex A
(normative)
Test report on melting temperatures of solder alloys

Enter the appropriate information in top portion of this report and complete it by entering the
test results. Add the measurements, values, pictures, and so on, as an attachment to this
report, see Table A.1.
Table A.1 – Report form
Date of measurement
Measuring equipment
Sample name
Sample size
Inert gas
Inert gas flow rate
Heating rate
Solidus temperature
Liquidus temperature
61189-11 © IEC:2013 – 13 –
Annex B
(informative)
Examples of test result (Method A)

Figure B.1 and Figure B.2 show examples of test results of liquidus temperature using
method A.
Sn96,5Ag3Cu,5
0 1 2 3
0,5 –0,5
Square root of heating rate  (°C × min )
IEC  1078/13
Figure B.1 – Example of test result (Method A: Sn96,5
...