IEC 60749-20:2020

IEC 60749-20 ®
Edition 3.0 2020-08
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 3.0 2020-08
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
INTERNATIONALE
ICS 31.080.01 ISBN 978-2-8322-8727-9

– 2 – IEC 60749-20:2020 © IEC 2020
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General description . 7
5 Test apparatus and materials . 7
5.1 Humidity chamber . 7
5.2 Reflow soldering apparatus . 8
5.3 Holder . 8
5.4 Wave-soldering apparatus . 8
5.5 Solvent for vapour-phase reflow soldering. 8
5.6 Flux . 8
5.7 Solder . 8
6 Procedure . 9
6.1 Initial measurements . 9
6.1.1 Visual inspection . 9
6.1.2 Electrical measurement . 9
6.1.3 Internal inspection by acoustic tomography . 9
6.2 Drying . 9
6.3 Moisture soak . 9
6.3.1 General . 9
6.3.2 Conditions for non-dry-packed SMDs . 9
6.3.3 Moisture soak for dry-packed SMDs . 10
6.4 Soldering heat . 11
6.4.1 General . 11
6.4.2 Method of heating by infrared convection or convection reflow soldering . 12
6.4.3 Method of heating by vapour-phase reflow soldering . 13
6.4.4 Method of heating by wave-soldering . 13
6.5 Recovery . 14
6.6 Final measurements . 15
6.6.1 Visual inspection . 15
6.6.2 Electrical measurement . 15
6.6.3 Internal inspection by acoustic tomography . 15
7 Information to be given in the relevant specification . 15
Annex A (informative) Details and description of test method on resistance of plastic
encapsulated SMDs to the combined effect of moisture and soldering heat . 17
A.1 Description of moisture soak . 17
A.1.1 Guidance for moisture soak . 17
A.1.2 Considerations on which the condition of moisture soak is based . 17
A.2 Procedure for moisture content measurement . 22
A.3 Soldering heat methods . 23
A.3.1 Temperature profile of infrared convection and convection reflow
soldering . 23
A.3.2 Temperature profile of vapour-phase soldering . 25
A.3.3 Heating method by wave-soldering . 26

Figure 1 – Method of measuring the temperature profile of a specimen . 8
Figure 2 – Heating by wave-soldering . 14
Figure A.1 – Process of moisture diffusion at 85 °C, 85 % RH. 18
Figure A.2 – Definition of resin thickness and the first interface . 18
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 . 19
Figure A.5 – Dependence of moisture content of resin at the first interface on resin
thickness under various soak conditions . 20
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 . 22
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 . 24
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 . 27
Figure A.15 – Temperature in the body of the SMD during wave-soldering . 27

Table 1 – Moisture soak conditions for non-dry-packed SMDs . 9
Table 2 – Moisture soak conditions for dry-packed SMDs (method A) . 10
Table 3 – Moisture soak conditions for dry-packed SMDs (method B) . 11
Table 4 – SnPb eutectic process – Classification reflow temperatures (T ) . 12
c
Table 5 – Pb-free process – Classification reflow temperatures (T ) .
...