IEC 60749-20:2008

IEC 60749-20
Edition 2.0 2008-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Semiconductor devices – Mechanical and climatic test methods –
Part 20: Resistance of plastic encapsulated SMDs to the combined effect of
moisture and soldering heat
Dispositifs à semiconducteurs – Méthodes d'essais mécaniques et climatiques –
Partie 20: Résistance des CMS à boîtier plastique à l'effet combiné de l'humidité
et de la chaleur de brasage
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IEC 60749-20
Edition 2.0 2008-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Semiconductor devices – Mechanical and climatic test methods –
Part 20: Resistance of plastic encapsulated SMDs to the combined effect of
moisture and soldering heat
Dispositifs à semiconducteurs – Méthodes d'essais mécaniques et climatiques –
Partie 20: Résistance des CMS à boîtier plastique à l'effet combiné de l'humidité
et de la chaleur de brasage
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
U
CODE PRIX
ICS 31.080.01 ISBN 978-2-88910-284-6
– 2 – 60749-20 © IEC:2008
CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references.6
3 General description.6
4 Test apparatus and materials.6
4.1 Humidity chamber.6
4.2 Reflow soldering apparatus.6
4.3 Holder .7
4.4 Wave-soldering apparatus .7
4.5 Solvent for vapour-phase reflow soldering.7
4.6 Flux.7
4.7 Solder .7
5 Procedure.7
5.1 Initial measurements .7
5.1.1 Visual inspection.7
5.1.2 Electrical measurement.8
5.1.3 Internal inspection by acoustic tomography .8
5.2 Drying.8
5.3 Moisture soak .8
5.3.1 General .8
5.3.2 Conditions for non-dry-packed SMDs .8
5.3.3 Moisture soak for dry-packed SMDs .8
5.4 Soldering heat .10
5.4.1 General .10
5.4.2 Method of heating by infrared convection or convection reflow
soldering.11
5.4.3 Method of heating by vapour-phase reflow soldering.12
5.4.4 Method of heating by wave-soldering.12
5.5 Recovery .13
5.6 Final measurements .14
5.6.1 Visual inspection.14
5.6.2 Electrical measurement.14
5.6.3 Internal inspection by acoustic tomography .14
6 Information to be given in the relevant specification.14
Annex A (informative) Details and descriptions of test method on resistance of plastic
encapsulated SMDs to the combined effect of moisture and soldering heat.16

Figure 1 – Method of measuring the temperature profile of a specimen.7
Figure 2 – Heating by wave-soldering .13
Figure A.1 – Process of moisture diffusion at 85 °C, 85 % RH.17
Figure A.2 – Definition of resin thickness and the first interface .17
Figure A.3 – Moisture soak time to saturation at 85 °C as a function of resin thickness .18
Figure A.4 – Temperature dependence of saturated moisture content of resin.18
Figure A.5 – Dependence of moisture content of resin at the first interface on resin
thickness under various soak conditions.19

60749-20 © IEC:2008 – 3 –
Figure A.6 – Dependence of moisture content of resin at the first interface on resin
thickness related to method A of moisture soak .20
Figure A.7 – Dependence of the moisture content of resin at the first interface on resin
thickness related to method B of moisture soak .21
Figure A.8 – Dependence of moisture content of resin at the first interface on resin
thickness related to condition B2 of method B of moisture soak .21
Figure A.9 – Temperature profile of infrared convection and convection reflow soldering
for Sn-Pb eutectic assembly.23
Figure A.10 – Temperature profile of infrared convection and convection reflow
soldering for lead-free assembly.23
Figure A.11 – Classification profile .25
Figure A.12 – Temperature profile of vapour-phase soldering (condition II-A).25
Figure A.13 – Immersion method into solder bath .26
Figure A.14 – Relation between the infrared convection reflow soldering and wave-
soldering.26
Figure A.15 – Temperature in the body of the SMD during wave-soldering .27

Table 1 – Moisture soak conditions for non-dry-packed SMDs .8
Table 2 – Moisture soak conditions for dry-packed SMDs (method A) .9
Table 3 – Moisture soak conditions for dry-packed SMDs (method B) .10
Table 4 – SnPb eutectic process – Classification reflow temperatures .11
Table 5 – Pb-free process – Classification reflow temperatures .12
Table 6 – Heating condition for vapour-phase soldering .12
Table 7 – Immersion conditions for wave-soldering.13
Table A.1 – Comparison of actual storage conditions and equivalent moisture soak

conditions before soldering heat.18
Table A.2 – Classification profiles.24

– 4 – 60749-20 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SEMICONDUCTOR DEVICES –
MECHANICAL AND CLIMATIC TEST METHODS –

Part 20: Resistance of plastic encapsulated SMDs to
the combined effect of moisture and soldering heat

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaisi
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