Semiconductor devices - Mechanical and climatic test methods - Part 20: Resistance of plastic encapsulated SMDs to the combined effect of moisture and soldering heat

IEC 60749-20:2020 is available as IEC 60749-20:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60749-20:2020 provides a means of assessing the resistance to soldering heat of semiconductors packaged as plastic encapsulated surface mount devices (SMDs). This test is destructive. This edition includes the following significant technical changes with respect to the previous edition:
- incorporation of a technical corrigendum to IEC 60749-20:2008 (second edition );
- inclusion of new Clause 3;
- inclusion of explanatory notes.

Dispositifs à semiconducteurs - Méthodes d'essais mécaniques et climatiques - Partie 20 : Résistances des CMS à boîtier plastique à l’effet combiné de l’humidité et de la chaleur de brasage

IEC 60749-20:2020 est disponible sous forme de IEC 60749-20:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L’IEC 60749-20:2020 fournit des moyens d’évaluer la résistance à la chaleur de brasage des semiconducteurs sous emballage comme les composants à boîtier plastique pour montage en surface (CMS). Cet essai est destructif. Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
- incorporation d’un corrigendum de l’IEC 60749-20:2008 (deuxième édition),
- inclusion d’un nouvel Article 3,
- inclusion de notes explicatives.

General Information

Status
Published
Publication Date
30-Aug-2020
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
31-Aug-2020
Ref Project

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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
IEC 60749-20:2020-08(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
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

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 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

---------------------- Page: 4 ----------------------
IEC 60749-20:2020 © IEC 2020 – 3 –

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

Table 5 – Pb-free process – Classification reflow temperatures (T ) ..................................... 13

Table 6 – Heating condition for vapour-phase soldering ........................................................ 13

Table 7 – Immersion conditions for wave-soldering ............................................................... 14

Table A.1 – Comparison of actual storage conditions and equivalent moisture soak

conditions before soldering heat ........................................................................................... 19

Table A.2 – Classification profiles ......................................................................................... 24

---------------------- Page: 5 ----------------------
– 4 – IEC 60749-20:2020 © IEC 2020
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

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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

consensus of opinion on the relevant subjects since each technical committee has representation from all

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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

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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 60749-20 has been prepared by IEC technical committee 47:

Semiconductor devices.

This third edition cancels and replaces the second edition published in 2008. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:

a) incorporation of a technical corrigendum to IEC 60749-20:2008 (second edition );

b) inclusion of new Clause 3;
c) inclusion of explanatory notes.
---------------------- Page: 6 ----------------------
IEC 60749-20:2020 © IEC 2020 – 5 –
The text of this International Standard is based on the following documents:
FDIS Report on voting
47/2634/FDIS 47/2646/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 60749 series, published under the general title Semiconductor

devices – Mechanical and climatic test methods, 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 "http://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.
---------------------- Page: 7 ----------------------
– 6 – IEC 60749-20:2020 © IEC 2020
SEMICONDUCTOR DEVICES –
MECHANICAL AND CLIMATIC TEST METHODS –
Part 20: Resistance of plastic encapsulated SMDs to
the combined effect of moisture and soldering heat
1 Scope

This part of IEC 60749 provides a means of assessing the resistance to soldering heat of

semiconductors packaged as plastic encapsulated surface mount devices (SMDs). This test is

destructive.
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 60068-2-20:2008, Environmental testing – Part 2-20: Tests – Test T: Test methods for

solderability and resistance to soldering heat of devices with leads

IEC 60749-3, Semiconductor devices – Mechanical and climatic test methods – Part 3:

External visual examination

IEC 60749-30, Semiconductor devices – Mechanical and climatic test methods – Part 30:

Preconditioning of non-hermetic surface mount devices prior to reliability testing

IEC 60749-35, Semiconductor devices – Mechanical and climatic test methods – Part 35:

Acoustic microscopy for plastic encapsulated electronic components
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
acoustic tomography

determination of the physical qualities of a known substance by measuring how long it takes

sound to travel through it
3.2
classification reflow temperature

maximum body temperature for which the component moisture sensitivity level (MSL) is

verified by the component manufacturer and as noted on the caution and/or bar code label

---------------------- Page: 8 ----------------------
IEC 60749-20:2020 © IEC 2020 – 7 –
3.3
crack
separation within a bulk material
Note 1 to entry: See also delamination (3.5).
3.4
dead-bug orientation
orientation of a package with the terminals facing upwards
3.5
delamination
interfacial separation between two materials intended to be bonded
Note 1 to entry: See also crack (3.3).
3.6
floor life

allowable time period after removal from a moisture barrier bag, dry storage, or dry bake and

before the solder reflow process

Note 1 to entry: For the purposes of this document "‘unlimited" floor life only refers to moisture/reflow related

failures and does not take into consideration other failure mechanisms or shelf life issues due to long term storage.

3.7
live-bug orientation
orientation of a package when resting on its terminals
3.8
moisture sensitivity level
MSL

rating indicating a component’s susceptibility to damage due to absorbed moisture when

subjected to reflow soldering
3.9
soak

exposure of a component for a specified time at a specified temperature and humidity

4 General description

Package cracking and electrical failure in plastic encapsulated SMDs can result when

soldering heat raises the vapour pressure of moisture which has been absorbed into SMDs

during storage. These problems are assessed. In this test method, SMDs are evaluated for

heat resistance after being soaked in an environment which simulates moisture being

absorbed while under storage in a warehouse or dry pack. Moisture sensitivity level (MSL)

ratings generated by this document are utilized to determine the soak conditions for

preconditioning in accordance with IEC 60749-30.
5 Test apparatus and materials
5.1 Humidity chamber

The humidity chamber shall provide an environment complying with the temperature and

relative humidity defined in 6.3.
---------------------- Page: 9 ----------------------
– 8 – IEC 60749-20:2020 © IEC 2020
5.2 Reflow soldering apparatus

The infrared convection, the convection and the vapour-phase reflow soldering apparatus

shall provide temperature profiles complying with the conditions of soldering heat defined in

6.4.2 and 6.4.3. The settings of the reflow soldering apparatus shall be adjusted by

temperature profiling of the top surface of the specimen while it is undergoing the soldering

heat process, measured as shown in Figure 1.
The adhesive agent or thin tape should have good thermal conductivity.
Figure 1 – Method of measuring the temperature profile of a specimen
5.3 Holder

Unless otherwise detailed in the relevant specification, any board material, such as epoxy

fibreglass or polyimide, may be used for the holder. The specimen shall be placed on the

holder by the usual means and in a position as shown in Figure 1. If the position of the

specimen, as shown in Figure 1, necessitates changing the shape of terminations and results

in subsequent electrical measurement anomalies, a position that avoids changing the shape

of terminations may be chosen, and this shall be specified in the relevant specification.

5.4 Wave-soldering apparatus

The wave-soldering apparatus shall comply with conditions given in 6.4.4. Molten solder shall

usually be flowed.
5.5 Solvent for vapour-phase reflow soldering
Perfluorocarbon (perfluoroisobutylene) shall be used.
5.6 Flux

Unless otherwise detailed in the relevant specification, the flux shall consist of 25 % by weight

of colophony in 75 % by weight of isopropyl alcohol, both as specified in Annex B of

IEC 60068-2-20:2008.
5.7 Solder

A solder of the composition as specified in Table 1 of IEC 60068-2-20:2008 shall be used.

---------------------- Page: 10 ----------------------
IEC 60749-20:2020 © IEC 2020 – 9 –
6 Procedure
6.1 Initial measurements
6.1.1 Visual inspection

Visual inspection, as specified in IEC 60749-3, shall be performed before the test. Special

attention shall be paid to external cracks and swelling, which will be looked for under a

magnification of 40X.
6.1.2 Electrical measurement
Electrical testing shall be performed as required by the relevant specification.
6.1.3 Internal inspection by acoustic tomography

Unless otherwise detailed in the relevant specification, internal cracks and delamination in the

specimen shall be inspected by acoustic tomography in accordance with IEC 60749-35.

6.2 Drying

Unless otherwise detailed in the relevant specification, the specimen shall be baked at

125 °C ± 5 °C for at least 24 h.

NOTE 1 This time/temperature is modified if desorption data on the particular device under test shows that a

different condition is required to obtain a "dry" package when starting in the wet condition for 85 °C/85 % RH.

NOTE 2 If a bake test is interrupted for more than 15 min, then the total time of the interruption is excluded from

the bake time. The interruption time is taken into account (if no greater than 1 h) then re-incorporated to ensure a

minimum of 24 h. For instance, if the interruption was 45 min, then the total bake test time would be 24 h and

45 min. If greater than 1 h the bake is restarted for a full 24 h.
6.3 Moisture soak
6.3.1 General

Unless otherwise detailed in the relevant specification, moisture soak conditions shall be

selected on the basis of the packing method of the specimen (see A.1.1, Annex A). If baking

the specimen before soldering is detailed in the relevant specification, the specimen shall be

baked instead of being subjected to moisture soak.
6.3.2 Conditions for non-dry-packed SMDs

The moisture soak condition shall be selected from Table 1, in accordance with the

permissible limit of actual storage (see A.1.2.1).
Table 1 – Moisture soak conditions for non-dry-packed SMDs
Temperature Relative humidity Duration time
Permissible limit on
Condition
actual storage
°C % h
A1 or B1 85 ± 2 85 ± 5 168 ± 24 < 30 °C, 85 % RH
RH: relative humidity

NOTE Conditions A1 and B1 indicate moisture soak for non-dry-packed SMDs under either method A or B.

---------------------- Page: 11 ----------------------
– 10 – IEC 60749-20:2020 © IEC 2020
6.3.3 Moisture soak for dry-packed SMDs
6.3.3.1 General

Moisture soak conditions for dry-packed SMDs may be used as specified in method A, Table 2,

or method B, Table 3. Moisture soak conditioning for dry-packed SMDs consists of two stages.

The first stage of conditioning is intended to simulate moisturizing SMDs before opening the

dry pack/dry cabinet. The second stage of conditioning is to simulate moisturizing SMDs

during storage after opening the dry pack for soldering (floor life). Moisture soak conditioning

for dry-packed SMDs shall be selected from method A or B. Method A shall be used when the

relative humidity in the dry pack or dry cabinet is specified by the manufacturer as being

between 10 % and 30 %. Method B shall be used when the relative humidity in the dry pack or

dry cabinet is specified by the manufacturer as being below 10 %.
6.3.3.2 Method A

Unless otherwise detailed in the relevant specification, the first stage conditioning of A2, as

shown in Table 2, shall be performed. Subsequently, the second stage conditioning of A2, as

shown in Table 2, shall be perf
...

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