EN IEC 60068-2-20:2021

Environmental testing - Part 2-20: Tests - Test Ta and Tb: Test methods for solderability and resistance to soldering heat of devices with leads

IEC 60068-2-20:2021 is available as IEC 60068-2-20:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60068-2-20:2021 outlines Tests Ta and Tb, applicable to devices with leads and leads themselves. Soldering tests for surface mounting devices (SMD) are described in IEC 60068‑2‑58. This document provides procedures for determining the solderability and resistance to soldering heat of devices in applications using solder alloys, which are eutectic or near eutectic tin lead (Pb), or lead-free alloys. The procedures in this document include the solder bath method and soldering iron method. The objective of this document is to ensure that component lead or termination solderability meets the applicable solder joint requirements of IEC 61191-3 and IEC 61191-4. In addition, test methods are provided to ensure that the component body can be resistant to the heat load to which it is exposed during soldering. This edition includes the following significant technical changes with respect to the previous edition: - update of and clarification of pre-conditioning (former "aging") and its relation to natural aging.

Umgebungseinflüsse - Teil 2-20: Prüfungen - Prüfung Ta und Tb: Prüfverfahren für die Lötbarkeit und Lötwärmebeständigkeit von Bauelementen mit herausgeführten Anschlüssen

Essais d’environnement - Partie 2-20: Essais - Essais Ta et Tb: Méthodes d'essai de la brasabilité et de la résistance à la chaleur de brasage des dispositifs à broches

IEC 60068-2-20:2021 est disponible sous forme de IEC 60068-2-20:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 60068-2-20:2021 décrit les essais Ta et Tb qui s’appliquent aux dispositifs à broches et aux broches elles-mêmes. Les essais de brasage des composants pour montage en surface (CMS) sont décrits dans l’IEC 60068-2-58. Le présent document fournit des procédures pour déterminer la brasabilité et la résistance à la chaleur de brasage des dispositifs dans les applications qui utilisent des alliages de brasure, qui sont soit des brasures étain plomb (Pb) eutectique ou quasi eutectique, soit des alliages de brasure sans plomb. Les procédures du présent document incluent les méthodes dites de bain de brasage et de fer à braser. Le but du présent document est d’assurer que les broches des composants ou la brasabilité de leurs bornes sont en mesure de satisfaire aux exigences applicables aux joints de brasures de l’IEC 61191-3 et de l’IEC 61191-4. De plus, des méthodes d’essai sont fournies pour assurer que le corps du composant peut résister à la charge calorifique à laquelle il est exposé pendant le brasage. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - mise à jour et clarification du préconditionnement (auparavant "vieillissement") et sa relation au vieillissement naturel.

Okoljski preskusi - 2-20. del: Preskusi - Preskusa Ta in Tb: Preskusne metode za določanje spajkljivosti in odpornosti proti toploti spajkanja za komponente z izvodi

General Information

• Status: Published
• Publication Date: 06-May-2021
• ICS: 19.040 - Environmental testing
• Technical Committee: CLC/SR 91 - Electronics assembly technology
• Drafting Committee: IEC/TC 91 - IEC_TC_91
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 07-May-2021
• Completion Date: 07-May-2021
• Ref Project: SIST EN IEC 60068-2-20:2021 - Environmental testing - Part 2-20: Tests - Test T: Test methods for solderability and resistance to soldering heat of devices with leads

Relations

• Replaces: EN 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
• Effective Date: 23-Jul-2019

Overview

EN IEC 60068-2-20:2021 - Environmental testing, Part 2-20 - defines Test Ta and Tb: standardized methods to assess solderability and resistance to soldering heat of devices with leads. This 2021 (6th) edition updates pre‑conditioning (formerly “aging”) and clarifies its relation to natural aging. The standard covers components with through‑lead terminations and specifies both the solder bath and soldering iron test methods for eutectic/near‑eutectic tin‑lead (Pb) and lead‑free solder alloys.

Key topics and technical requirements

• Scope & Objective: Determine that component leads/terminations wet adequately and that component bodies withstand soldering heat without unacceptable damage.
• Tests Ta and Tb:
  • Test Ta (Solderability) - verifies that wire, tag and lead terminations accept solder using controlled exposure times and temperatures.
  • Test Tb (Resistance to soldering heat) - evaluates the ability of the component to survive exposure to solder heat without degradation.
• Test methods:
  • Solder bath method - immersion in a temperature‑controlled solder bath; defined severities (time/temperature).
  • Soldering iron method - local heat application using specified irons at controlled temperatures and contact times.
• Pre‑conditioning: Procedures for preparing specimens (formerly “aging”) are updated and its relation to natural aging is clarified - important for realistic assessment of fielded parts.
• Measurements and acceptance criteria: Final inspections and pass/fail criteria ensure solderability and thermal resistance meet the requirements referenced for solder joints.
• Flux and materials: Flux compositions and solder alloy types are specified; normative annexes provide flux guidance.

Practical applications

• Ensuring component leads meet manufacturing and field reliability requirements during wave or hand soldering processes.
• Qualification testing for new components or alternative termination finishes (including lead‑free alloys).
• Input to incoming inspection, vendor qualification and failure analysis for electronics assembly.
• Defining test conditions for components intended for through‑hole assemblies or terminal soldering processes.

Who uses this standard

• Component manufacturers and design engineers
• PCB assemblers and process engineers
• Test laboratories and quality assurance teams
• OEMs and procurement/specification writers enforcing reliability and solderability requirements

Related standards

• IEC 60068-2-58 - solderability tests for SMD components
• IEC 61191-3 and IEC 61191-4 - requirements for through‑hole and terminal soldered assemblies
• IEC 60068-1 - general environmental testing guidance

EN IEC 60068-2-20:2021 is essential for anyone specifying or verifying solderability and heat resistance of leaded components in modern electronics manufacturing.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2021
Nadomešča:
SIST EN 60068-2-20:2009
Okoljski preskusi - 2-20. del: Preskusi - Preskusa Ta in Tb: Preskusne metode za
določanje spajkljivosti in odpornosti proti toploti spajkanja za komponente z
izvodi
Environmental testing - Part 2-20: Tests - Test T: Test methods for solderability and
resistance to soldering heat of devices with leads
Umgebungseinflüsse - Teil 2-20: Prüfungen - Prüfung T: Prüfverfahren für die Lötbarkeit
und Lötwärmebeständigkeit von Bauelementen mit herausgeführten Anschlüssen
Essais d'environnement - Partie 2-20: Essais - Essai T: Méthodes d'essai de la
brasabilité et de la résistance à la chaleur de brasage des dispositifs à broches
Ta slovenski standard je istoveten z: EN IEC 60068-2-20:2021
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 60068-2-20

NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2021
ICS 19.040 Supersedes EN 60068-2-20:2008 and all of its
amendments and corrigenda (if any)
English Version
Environmental testing - Part 2-20: Tests - Test Ta and Tb: Test
methods for solderability and resistance to soldering heat of
devices with leads
(IEC 60068-2-20:2021)
Essais d'environnement - Partie 2-20: Essais - Essais Ta et Umgebungseinflüsse - Teil 2-20: Prüfungen - Prüfung Ta
Tb: Méthodes d'essai de la brasabilité et de la résistance à und Tb: Prüfverfahren für die Lötbarkeit und
la chaleur de brasage des dispositifs à broches Lötwärmebeständigkeit von Bauelementen mit
(IEC 60068-2-20:2021) herausgeführten Anschlüssen
(IEC 60068-2-20:2021)
This European Standard was approved by CENELEC on 2021-05-04. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60068-2-20:2021 E

European foreword
The text of document 91/1701/FDIS, future edition 6 of IEC 60068-2-20, prepared by IEC/TC 91
"Electronics assembly technology" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 60068-2-20:2021.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022-02-04
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2024-05-04
document have to be withdrawn
This document supersedes EN 60068-2-20:2008 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Endorsement notice
The text of the International Standard IEC 60068-2-20:2021 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 60068-2-58 NOTE Harmonized as EN 60068-2-58
IEC 60068-2-69:2017 NOTE Harmonized as EN 60068-2-69:2017 (not modified)
IEC 61190-1-3:2017 NOTE Harmonized as EN IEC 61190-1-3:2018 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60068-1 - Environmental testing - Part 1: General EN 60068-1 -
and guidance
IEC 60068-2-2 - Environmental testing - Part 2-2: Tests - EN 60068-2-2 -
Test B: Dry heat
IEC 60068-2-66 - Environmental testing - Part 2: Test EN 60068-2-66 -
methods - Test Cx: Damp heat, steady
state (unsaturated pressurized vapour)
IEC 60068-2-78 - Environmental testing - Part 2-78: Tests - EN 60068-2-78 -
Test Cab: Damp heat, steady state
IEC 61191-3 - Printed board assemblies - Part 3: EN 61191-3 -
Sectional specification - Requirements
for through-hole mount soldered
assemblies
IEC 61191-4 - Printed board assemblies - Part 4: EN 61191-4 -
Sectional specification - Requirements
for terminal soldered assemblies

IEC 60068-2-20 ®
Edition 6.0 2021-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-20: Tests – Tests Ta and Tb: Test methods for solderability and

resistance to soldering heat of devices with leads

Essais d’environnement –
Partie 2-20: Essais – Essais Ta et Tb: Méthodes d'essai de la brasabilité

et de la résistance à la chaleur de brasage des dispositifs à broches

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-9585-4

– 2 – IEC 60068-2-20:2021 © IEC 2021
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Test Ta: Solderability of wire and tag terminations . 8
4.1 Objective and general description of the test . 8
4.1.1 Test methods . 8
4.1.2 Specimen preparation . 8
4.1.3 Initial measurements . 9
4.1.4 Preconditioning . 9
4.2 Method 1: Solder bath . 10
4.2.1 General . 10
4.2.2 Description of the solder bath . 10
4.2.3 Flux . 10
4.2.4 Procedure . 10
4.2.5 Test conditions . 11
4.2.6 Final measurements and requirements . 11
4.3 Method 2: Soldering iron at 350 °C . 11
4.3.1 General . 11
4.3.2 Description of soldering irons . 11
4.3.3 Solder and flux . 12
4.3.4 Procedure . 12
4.3.5 Final measurements and requirements . 13
4.4 Information to be given in the relevant specification . 13
5 Test Tb: Resistance to soldering heat . 14
5.1 Objective and general description of the test . 14
5.1.1 Test methods . 14
5.1.2 Initial measurements . 14
5.2 Method 1: Solder bath . 14
5.2.1 Description of the solder bath . 14
5.2.2 Flux . 14
5.2.3 Procedure . 14
5.2.4 Test conditions . 15
5.2.5 De-wetting . 15
5.3 Method 2: Soldering iron . 16
5.3.1 Description of soldering iron . 16
5.3.2 Solder and flux . 16
5.3.3 Procedure . 16
5.4 Recovery . 16
5.5 Final measurements and requirements . 16
5.6 De-wetting (if required) . 16
5.7 Information to be given in the relevant specification . 17
Annex A (informative) Example of apparatus for steam conditioning process . 18
Annex B (normative) Specification for flux constituents . 19
B.1 Colophony . 19
B.2 2-propanol (isopropyl alcohol) . 19

IEC 60068-2-20:2021 © IEC 2021 – 3 –
B.3 Ethyl alcohol . 19
B.4 Flux composition . 19
Bibliography . 21

Figure 1 – Diagram of contact angle . 7
Figure 2 – Position of soldering iron . 12
Figure A.1 – Example of apparatus . 18

Table 1 – Solderability, solder bath method: Test severities (duration and temperature) . 11
Table 2 – Resistance to soldering heat, solder bath method: Test severities (duration
and temperature) . 15
Table B.1 – Colophony based flux compositions . 20

– 4 – IEC 60068-2-20:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 2-20: Tests –
Tests Ta and Tb: Test methods for solderability
and resistance to soldering heat of devices with leads

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 liaising
with the IEC also participate in this preparation. IEC collaborates closely 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
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 60068-2-20 has been prepared by IEC technical committee 91: Electronics assembly
technology. It is an International Standard.
This sixth edition cancels and replaces the fifth edition published in 2008. This sixth edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) update of and clarification of pre-conditioning (former "aging") and its relation to natural
aging.
IEC 60068-2-20:2021 © IEC 2021 – 5 –
The text of this International Standard is based on the following documents:
Draft Report on voting
91/1701/FDIS 91/1711/RVD
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 the parts in the IEC 60068 series, under the general title Environmental testing, 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.
– 6 – IEC 60068-2-20:2021 © IEC 2021
ENVIRONMENTAL TESTING –
Part 2-20: Tests –
Tests Ta and Tb: Test methods for solderability
and resistance to soldering heat of devices with leads

1 Scope
This part of IEC 60068 outlines Tests Ta and Tb, applicable to devices with leads and leads
themselves. Soldering tests for surface mounting devices (SMD) are described in
IEC 60068‑2‑58.
This document provides procedures for determining the solderability and resistance to soldering
heat of devices in applications using solder alloys, which are eutectic or near eutectic tin lead
(Pb), or lead-free alloys.
The procedures in this document include the solder bath method and soldering iron method.
The objective of this document is to ensure that component lead or termination solderability
meets the applicable solder joint requirements of IEC 61191-3 and IEC 61191-4. In addition,
test methods are provided to ensure that the component body can be resistant to the heat load
to which it is exposed during soldering.
NOTE Information about wetting time and wetting force can be obtained by test methods using a wetting balance.
IEC 60068-2-69 (solder bath and solder globule method) can be consulted.
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 60068-1, Environmental testing – Part 1: General and guidance
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-66, Environmental testing – Part 2: Test methods – Test Cx: Damp heat, steady
state (unsaturated pressurized vapour)
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady state
IEC 61191-3, Printed board assemblies – Part 3: Sectional specification – Requirements for
through-hole mount soldered assemblies
IEC 61191-4, Printed board assemblies – Part 4: Sectional specification – Requirements for
terminal soldered assemblies
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

IEC 60068-2-20:2021 © IEC 2021 – 7 –
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
colophony
natural resin obtained as the residue after removal of turpentine from the oleo-resin of the pine
tree, consisting mainly of abietic acid and related resin acids, the remainder being resin acid
esters
Note 1 to entry: ”Rosin" is a synonym for colophony, and is deprecated because of the common confusion with the
generic term "resin".
3.2
contact angle
in general, the angle enclosed between two planes, tangent to a liquid surface and a solid/liquid
interface at their intersection (see Figure 1); in particular, the contact angle of liquid solder in
contact with a solid metal surface

Figure 1 – Diagram of contact angle
3.3
wetting
formation of an adherent coating of solder on a surface
Note 1 to entry: A small contact angle is indicative of wetting.
3.4
non-wetting
inability to form an adherent coating of solder on a surface
Note 1 to entry: In this case the contact angle is greater than 90°.
3.5
de-wetting
retraction of molten solder on a solid area that it has initially wetted
Note 1 to entry: In some cases, an extremely thin film of solder may remain. As the solder retracts the contact angle
increases.
3.6
solderability
ability of the lead, termination or electrode of a component to be wetted by solder at the
temperature of the termination or electrode, which is assumed to be the lowest temperature in
the soldering process within the applicable temperature range of the solder alloy

– 8 – IEC 60068-2-20:2021 © IEC 2021
3.7
soldering time
time required for a defined surface area to be wetted under specific conditions
3.8
resistance to soldering heat
ability of the component to withstand the highest temperature stress in terms of temperature
gradient, peak temperature and duration of the soldering process, where the temperature of the
component body is within the applicable temperature range of the solder alloy
3.9
lead-free solder
alloy that does not contain more than 0,1 % lead (Pb) by weight as its constituent and is used
for joining components to substrates or for coating surfaces
[SOURCE: IEC 60194-2:2017, 3.12.5, modified – The words "as its constituent" have been
added.]
4 Test Ta: Solderability of wire and tag terminations
4.1 Objective and general description of the test
4.1.1 Test methods
Test Ta provides two different test methods to determine the solderability of areas on wire and
tag terminations that are required to be wetted by solder during the assembly operation.
– Method 1: solder bath;
– Method 2: soldering iron.
The test method to be used shall be indicated in the relevant specification. The solder bath
method is the one which most closely simulates the soldering procedures of flow soldering and
similar soldering processes.
The soldering iron method may be used in cases where Method 1 is impracticable.
If required by the relevant specification, the test specimen shall be preconditioned according to
4.1.4.
...