IEC 61191-3:2017

Printed board assemblies - Part 3: Sectional specification - Requirements for through-hole mount soldered assemblies

IEC 61191-3:2017 prescribes requirements for lead and hole solder assemblies. The requirements pertain to those assemblies that totally use through-hole mounting technology (THT), or the THT portions of those assemblies that include other related technologies (i.e.. surface mount, chip mounting, terminal mounting).
This edition includes the following significant technical changes with respect to the previous edition:
a) The requirements have been updated to be compliant wit the acceptance criteria in IPC-A-610F.

Ensembles de cartes imprimées - Partie 3: Spécification intermédiaire - Exigences relatives à l'assemblage par brasage de trous traversants

L’IEC 61191-3:2017 décrit les exigences relatives aux ensembles de composants à trous traversants (broches et trous) montés par brasage. Les exigences s’appliquent aux ensembles utilisant totalement une technique de montage par trous traversants (THT) ou aux portions THT d’ensembles incluant d’autres techniques associées (par exemple montage en surface, montage à puce, montage à borne).
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) mise à jour des exigences pour qu’elles soient conformes aux critères d’acceptation de l’IPC‑A-610F.

General Information

• Status: Published
• Publication Date: 29-May-2017
• ICS: 31.240 - Mechanical structures for electronic equipment
• Technical Committee: TC 91 - Electronics assembly technology
• Drafting Committee: WG 2 - TC 91/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 30-May-2017
• Completion Date: 26-Jun-2017

Relations

• Revises: IEC 61191-3:1998 - Printed board assemblies - Part 3: Sectional specification - Requirements for through-hole mount soldered assemblies
• Effective Date: 05-Sep-2023

Overview

IEC 61191-3:2017 - "Printed board assemblies - Part 3: Sectional specification - Requirements for through-hole mount soldered assemblies" - prescribes requirements for assemblies that use through‑hole technology (THT) or the THT portions of mixed-technology assemblies. This 2017 edition (Edition 2.0) updates acceptance and workmanship requirements to align with the acceptance criteria in IPC‑A‑610F.

Key topics

• Scope and applicability
  • Requirements apply to lead-and-hole solder assemblies for fully THT assemblies or THT sections of mixed assemblies.
• Mandatory references
  • Incorporates requirements of IEC 61191‑1 (generic soldered assembly specification) and refers to IEC 60194 terms and definitions.
• Workmanship and acceptability
  • Workmanship must meet IPC‑A‑610 classification requirements; acceptance criteria updated to be compliant with IPC‑A‑610F.
• Placement accuracy
  • Components must be positioned so that final post‑solder placement is correct; Annex A provides detailed placement requirements and mounting configurations.
• Lead forming and preforming
  • Leads must be pre‑formed to final configuration (excluding final clinch/retention bend) and must not damage the lead‑to‑body seal.
  • Leads must extend at least one lead diameter (but not less than 0.8 mm) before the start of the bend radius.
  • Accepts limited exposed core metal if cross‑section reduction ≤10% - treated as a process indicator.
• Through‑hole solder joint requirements
  • Acceptance, control and corrective action clauses cover plated/non‑plated through‑holes, via connections, clinched leads, fillet requirements, and defects.
• Rework
  • Procedures and limits for reworking unsatisfactory solder joints are included to preserve component integrity and board reliability.
• Annexes, figures and tables
  • Annex A contains placement requirements and detailed mounting illustrations; the standard includes figures and tables on lead bends, hole obstruction, fillet requirements, and defect classification.

Applications

IEC 61191‑3:2017 is used by:

• PCB designers and assembly engineers to define THT placement, forming and soldering requirements.
• Contract manufacturers and electronics assemblers for process control, inspection criteria and acceptance sampling.
• Quality/inspection teams and compliance officers to enforce workmanship standards consistent with IPC‑A‑610F.
• Procurement and product documentation to specify THT assembly acceptance in contracts and production drawings.

Related standards

• IEC 61191‑1:2013 - Generic specification for soldered assemblies
• IEC 60194 - Printed board design, manufacture and assembly - Terms and definitions
• IPC‑A‑610 (IPC‑A‑610F) - Acceptability of Electronic Assemblies (acceptance criteria alignment)

Keywords: IEC 61191-3:2017, through-hole, THT, printed board assemblies, through-hole mount soldered assemblies, IPC-A-610F, lead forming, placement accuracy, plated through-holes, clinched leads, rework.

Standards Content (Sample)

IEC 61191-3 ®
Edition 2.0 2017-05
INTERNATIONAL
STANDARD
Printed board assemblies –
Part 3: Sectional specification – Requirements for through-hole mount soldered
assemblies
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
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Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

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IEC 61191-3 ®
Edition 2.0 2017-05
INTERNATIONAL
STANDARD
Printed board assemblies –
Part 3: Sectional specification – Requirements for through-hole mount soldered

assemblies
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.240 ISBN 978-2-8322-4397-8

– 2 – IEC 61191-3:2017 © IEC 2017

CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General requirements . 6
5 Through-hole mounting of components . 7
5.1 General . 7
5.2 Placement accuracy . 7
5.3 Through-hole component requirements . 7
5.3.1 Lead preforming . 7
5.3.2 Tempered leads . 7
5.3.3 Lead forming requirements . 7
5.3.4 Stress relief requirements . 8
5.3.5 Lead termination requirements . 8
6 Acceptance requirements . 10
6.1 General . 10
6.2 Control and corrective actions . 10
6.2.1 General . 10
6.2.2 Interfacial connections (vias) . 10
6.3 Through-hole component lead soldering . 11
6.3.1 General . 11
6.3.2 Clinched leads . 12
6.3.3 Exposed basis metal . 13
7 Rework of unsatisfactory solder connections . 13
Annex A (normative) Placement requirements for through-hole mount devices . 14
A.1 General . 14
A.2 Horizontal mounting, free-standing . 14
A.3 Axial lead components . 14
A.4 Radial lead components . 14
A.5 Perpendicular mounting, free-standing . 14
A.5.1 General . 14
A.5.2 Mounting of components . 14
A.5.3 Radial lead components . 15
A.6 Side- and end-mounting . 15
A.7 Supported component mounting . 16
A.7.1 General . 16
A.7.2 Stand-off positioning . 16
A.7.3 Non-resilient footed stand-offs . 17
A.8 Stress relief lead configuration . 17
A.9 Flat pack lead configuration . 17
Bibliography . 19

Figure 1 – Lead bends . 8
Figure 2 – Hole obstruction . 10
Figure 3 – Through-hole component lead soldering . 11

Figure 4 – Lead-to-land fillet requirements for clinched leads and wires in non-plated
through-holes . 11
Figure 5 – Lead-to-land fillet requirements for clinched leads and wires in plated
through-holes . 12
Figure A.1 – Mounting of free-standing components . 14
Figure A.2 – Typical configuration of components with dual non-axial leads . 15
Figure A.3 – Mounting of components with dual non-axial leads . 15
Figure A.4 – Side mounting . 15
Figure A.5 – End mounting. 16
Figure A.6 – Mounting with footed stand-offs . 16
Figure A.7 – Non-resilient footed stand-offs . 17
Figure A.8 – Acceptable lead configurations . 17
Figure A.9 – Configuration of ribbon leads for through-hole mounting . 18

Table 1 – Plated through-holes with component leads, minimum acceptable
1)
conditions . 12
Table 2 – Through-hole solder joint defects . 13

– 4 – IEC 61191-3:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRINTED BOARD ASSEMBLIES –
Part 3: Sectional specification – Requirements
for through-hole mount soldered assemblies

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.
International Standard IEC 61191-3 has been prepared by WG 2: Requirements for electronics
assemblies, of IEC technical committee 91: Electronics assembly technology.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The requirements have been updated to be compliant with the acceptance criteria in
IPC-A-610F.
The text of this standard is based on the following documents:
CDV Report on voting
91/1375/CDV 91/1435/RVC
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 61191 series, published under the general title Printed board
assemblies, 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 61191-3:2017 © IEC 2017
PRINTED BOARD ASSEMBLIES –
Part 3: Sectional specification – Requirements
for through-hole mount soldered assemblies

1 Scope
This part of IEC 61191 prescribes requirements for lead and hole solder assemblies. The
requirements pertain to those assemblies that totally use through-hole mounting technology
(THT), or the THT portions of those assemblies that include other related technologies (i.e.
surface mount, chip mounting, terminal mounting).
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 60194, Printed board design, manufacture and assembly – Terms and definitions
IEC 61191-1:2013, Printed board assemblies – Part 1: Generic specification – Requirements
for soldered electrical and electronic assemblies using surface mount and related assembly
technologies
IPC-A-610, Acceptability of Electronic Assemblies
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60194 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
THT
through-hole technology
technology that permits an electrical connection of components to a conductive pattern by the
use of plated or non-plated holes with annular rings in the mounting substrate
4 General requirements
Requirements of IEC 61191-1 are a mandatory part of this specification. Workmanship shall
meet the requirements of IPC-A-610 in accordance with the classification requirements of this
document.
5 Through-hole mounting of components
5.1 General
This clause covers the assembly of components with leads inserted into through-holes and
soldered by machine and/or manual processes.
5.2 Placement accuracy
Placement accuracy for components inserted either manually or by machine methods shall be
sufficient to insure that components are properly positioned after soldering. If suitable process
controls are not in place to ensure compliance with this requirement and the intent of Annex
A, the detailed requirements of Annex A shall be applicable.
5.3 Through-hole component requirements
5.3.1 Lead preforming
Part and component leads shall be pre-formed to the final configuration, excluding the final
clinch or retention bend, before assembly or installation.
5.3.2 Tempered leads
When it is necessary to cut tempered leads, the governing work instructions shall specify
cutting tools that do not impart detrimental shocks to internal connections of the components.
5.3.3 Lead forming requirements
Leads shall be formed in such a manner that the lead-to-body seal is not damaged or
degraded. Leads shall extend at least one lead diameter or thickness but not less than
0,8 mm from the body or weld before the start of the bend radius (see Figure 1).
Exposed core metal is acceptable if reduction in the cross-sectional area does not exceed
10 % of the diameter of the lead. Occurrence of exposed core metal in the formed area of the
lead shall be treated as a process indicator.
Measurement shall be made from the end of the part. The end of the part is defined to include
any coating meniscus, solder seal, solder or weld bead, or any other extension.
The span for components mounted with a conventional lead form is 7,6 mm minimum, and
33 mm maximum.
– 8 – IEC 61191-3:2017 © IEC 2017

Straight for 1 diameter/lead thickness, Straight for 1 diameter/lead thickness,
but not less than 0,8 mm but not less than 0,8 mm
R
R
Weld
Diameter thickness
Diameter thickness
IEC IEC
a) Standard bend b) Welded bend

Maximum lead diameter Minimum bend radius
mm R
Up to 0,8 1 diameter/thickness
0,8 to 1,2 1,5 diameters/thicknesses
Larger than 1,2 2 diameters/thicknesses
Figure 1 – Lead bends
5.3.4 Stress relief requirements
Component leads shall be formed in such a manner that the lead compliancy is not restricted
in providing the natural stress relief of the lead material. Special lead formations are permitted
to enhance stress relief properties.
5.3.5 Lead termination requirements
5.3.5.1 General
To ensure part retention during soldering operations, lead terminations in printed board plated
through-holes shall be one of the following configurations: full clinch, partially clinched, or
straight-through lead termination, as specified on the assembly drawing. In the event
that n
...

IEC 61191-3 ®
Edition 2.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Printed board assemblies –
Part 3: Sectional specification – Requirements for through-hole mount soldered
assemblies
Ensembles de cartes imprimées –
Partie 3: Spécification intermédiaire – Exigences relatives à l’assemblage par
brasage de trous traversants
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
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IEC 61191-3 ®
Edition 2.0 2017-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Printed board assemblies –
Part 3: Sectional specification – Requirements for through-hole mount soldered

assemblies
Ensembles de cartes imprimées –

Partie 3: Spécification intermédiaire – Exigences relatives à l’assemblage par

brasage de trous traversants
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.240 ISBN 978-2-8322-7389-0

– 2 – IEC 61191-3:2017 © IEC 2017

CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General requirements . 6
5 Through-hole mounting of components . 7
5.1 General . 7
5.2 Placement accuracy . 7
5.3 Through-hole component requirements . 7
5.3.1 Lead preforming . 7
5.3.2 Tempered leads . 7
5.3.3 Lead forming requirements . 7
5.3.4 Stress relief requirements . 8
5.3.5 Lead termination requirements . 8
6 Acceptance requirements . 10
6.1 General . 10
6.2 Control and corrective actions . 10
6.2.1 General . 10
6.2.2 Interfacial connections (vias) . 10
6.3 Through-hole component lead soldering . 11
6.3.1 General . 11
6.3.2 Clinched leads . 12
6.3.3 Exposed basis metal . 13
7 Rework of unsatisfactory solder connections . 13
(normative) Placement requirements for through-hole mount devices . 14
A.1 General . 14
A.2 Horizontal mounting, free-standing . 14
A.3 Axial lead components . 14
A.4 Radial lead components . 14
A.5 Perpendicular mounting, free-standing . 14
A.5.1 General . 14
A.5.2 Mounting of components . 15
A.5.3 Radial lead components . 15
A.6 Side- and end-mounting . 15
A.7 Supported component mounting . 16
A.7.1 General . 16
A.7.2 Stand-off positioning . 17
A.7.3 Non-resilient footed stand-offs . 17
A.8 Stress relief lead configuration . 17
A.9 Flat pack lead configuration . 18
Bibliography . 19

Figure 1 – Lead bends . 8
Figure 2 – Hole obstruction . 10
Figure 3 – Through-hole component lead soldering . 11

Figure 4 – Lead-to-land fillet requirements for clinched leads and wires in non-plated
through-holes . 11
Figure 5 – Lead-to-land fillet requirements for clinched leads and wires in plated

through-holes . 12
Figure A.1 – Mounting of free-standing components . 14
Figure A.2 – Typical configuration of components with dual non-axial leads . 15
Figure A.3 – Mounting of components with dual non-axial leads . 15
Figure A.4 – Side mounting . 16
Figure A.5 – End mounting. 16
Figure A.6 – Mounting with footed stand-offs . 17
Figure A.7 – Non-resilient footed stand-offs . 17
Figure A.8 – Acceptable lead configurations . 18
Figure A.9 – Configuration of ribbon leads for through-hole mounting . 18

Table 1 – Plated through-holes with component leads, minimum acceptable
1)
conditions . 12
Table 2 – Through-hole solder joint defects . 13

– 4 – IEC 61191-3:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRINTED BOARD ASSEMBLIES –
Part 3: Sectional specification – Requirements
for through-hole mount soldered assemblies

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.
International Standard IEC 61191-3 has been prepared by WG 2: Requirements for electronics
assemblies, of IEC technical committee 91: Electronics assembly technology.
This bilingual version (2019-09) corresponds to the monolingual English version, published in
2017-05.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The requirements have been updated to be compliant with the acceptance criteria in
IPC-A-610F.
The text of this standard is based on the following documents:
CDV Report on voting
91/1375/CDV 91/1435/RVC
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.
The French version of this standard has not been voted upon.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61191 series, published under the general title Printed board
assemblies, 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 61191-3:2017 © IEC 2017
PRINTED BOARD ASSEMBLIES –
Part 3: Sectional specification – Requirements
for through-hole mount soldered assemblies

1 Scope
This part of IEC 61191 prescribes requirements for lead and hole solder assemblies. The
requirements pertain to those assemblies that totally use through-hole mounting technology
(THT), or the THT portions of those assemblies that include other related technologies (i.e.
surface mount, chip mounting, terminal mounting).
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 60194, Printed board design, manufacture and assembly – Terms and definitions
IEC 61191-1:2013, Printed board assemblies – Part 1: Generic specification – Requirements
for soldered electrical and electronic assemblies using surface mount and related assembly
technologies
IPC-A-610, Acceptability of Electronic Assemblies
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60194 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
THT
through-hole technology
technology that permits an electrical connection of components to a conductive pattern by the
use of plated or non-plated holes with annular rings in the mounting substrate
4 General requirements
Requirements of IEC 61191-1 are a mandatory part of this specification. Workmanship shall
meet the requirements of IPC-A-610 in accordance with the classification requirements of this
document.
5 Through-hole mounting of components
5.1 General
This clause covers the assembly of components with leads inserted into through-holes and
soldered by machine and/or manual processes.
5.2 Placement accuracy
Placement accuracy for components inserted either manually or by machine methods shall be
sufficient to insure that components are properly positioned after soldering. If suitable process
controls are not in place to ensure compliance with this requirement and the intent of Annex
A, the detailed requirements of Annex A shall be applicable.
5.3 Through-hole component requirements
5.3.1 Lead preforming
Part and component leads shall be pre-formed to the final configuration, excluding the final
clinch or retention bend, before assembly or installation.
5.3.2 Tempered leads
When it is necessary to cut tempered leads, the governing work instructions shall specify
cutting tools that do not impart detrimental shocks to internal connections of the components.
5.3.3 Lead forming requirements
Leads shall be formed in such a manner that the lead-to-body seal is not damaged or
degraded. Leads shall extend at least one lead diameter or thickness but not less than
0,8 mm from the body or weld before the start of the bend radius (see Figure 1).
Exposed core metal is acceptable if reduction in the cross-sectional area does not exceed
10 % of the diameter of the lead. Occurrence of exposed core metal in the formed area of the
lead shall be treated as a process indicator.
Measurement shall be made from the end of the part. The end of the part is defined to include
any coating meniscus, solder seal, solder or weld bead, or any other extension.
The span for components mounted with a conventional lead form is 7,6 mm minimum, and
33 mm maximum.
– 8 – IEC 61191-3:2017 © IEC 2017

Straight for 1 diameter/lead thickness, Straight for 1 diameter/lead thickness,
but not less than 0,8 mm but not less than 0,8 mm
R
R
Weld
Diameter thickness
Diameter thickness
IEC IEC
a) Standard bend b) Welded bend

Maximum lead diameter Minimum bend radius
mm R
Up to 0,8 1 diameter/thickness
0,8 to 1,2 1,5 diameters/thicknesses
Larger than 1,2 2 diameters/thicknesses
Figure 1 – Lead bends
5.3.4 Stress relief requirements
Component leads shall be formed in such a manner that the lead compliancy is not restricted
in providing the natural stress relief of the lead material. Special lead formations are permitted
to enhance stress relief properties.
5.3.5 Lead termination requirements
5.3.5.1 General
To ensure part retention during soldering operations, lead terminations in printed board plated
through-holes shall be one of the following configurations: full clinch, partially clinched, or
straight-through lead termination, as specified on the assembly drawing. In the event
that nothing is specified, the manufacturer shall conform to the requirements in 5.3.5.2 to
5.3.5.10 as appropriate.
5.3.5.2 Clinched lead termination
Leads in unsupported holes and class C shall be clinched a minimum of 45°. The lead end
should not extend beyond the edge of the land; however, if overhang does occur, the lead
extension shall not violate minimum electrical spacing requirements. Leads formed of alloy 42
or comparable iron bearing alloys shall not be terminated with a full clinch.
NOTE Alloy 42 has the composition of Fe-Ni 41-Mn 0,8-Co 0,5.
5.3.5.3 Clinched lead orientation
When manually clinched, the clinched portion of the wire or lead should be directed along a
printed conductor connected to the land. The leads on opposite ends or sides of a component
should be directed in opposite directions. When automatically clinched, the orientation of the
clinch relative to any conductor is optional. Manually formed clinches for non-axial leaded
components should be directed radially from the centre of the component when the
termination area array on the printed board is patterned for such radial orientation.

5.3.5.4 Partially clinched leads
Partially clinched leads shall be bent sufficiently to provide the necessary mechanical restraint
during the soldering process. Alternate bend directions may be used. Diagonally opposite
corner leads on dual-in-line packages (DIPs) may be partially clinched to retain parts during
soldering operations. DIP leads should be bent outwards away from the longitudinal axis of
the body.
5.3.5.5 Straight-through lead terminations
Component leads terminated straight through shall not extend in excess of 1,5 mm for level C,
or 2,5 mm for level B, and no danger of shorts for level C, beyond the conductor surface, and
as a minimum shall be visible in the completed solder connection. The lead protrusion for
unsupported holes shall be discernible in the solder joint for levels A and B, and sufficient to
clinch for level C. The maximum protrusion in all levels shall not create the risk of shorts.
Assembly designs that necessitate different lead extensions are considered to have unique
mounting requirements to be noted on the approved assembly drawing.
5.3.5.6 Meniscus spacing and trimming
Components shall be mounted to provide a visible clearance between the coating meniscus
on each lead and the solder connection. Trimming of the component coating meniscus is
prohibited.
5.3.5.7 Lead trimming
Leads may be trimmed after soldering, provided the cutters do not damage the component or
solder connection due to physical shock. When lead cutting is performed after soldering, the
solder terminations shall either be reflowed or visually inspected at 10 times magnification to
ensure that the original solder connection has not been damaged (e.g. fractured) or deformed.
If the solder connection is reflowed, this shall be considered a part of the soldering process
and shall not be considered rework. This requirement is not intended to apply to components
that are designed so that a portion of the lead is intended to be removed after soldering (e.g.
breakaway tie bars).
NOTE This inspection at 10 times magnification is to evaluate the soldered termination for evidence of physical
damage or deformation, indicated by fractures that are smaller than the land sizes inspected in accordance with
IEC 61191-1, provided that the breakpoint does not expose lead material that is corrodible (e.g. Kovar™ [Fe 54/Ni
29/Co 17])
5.3.5.8 Hole obstruction
Components shall be mounted so that they do not obstruct solder flow onto the upper side
lands of plated through-holes required to be soldered (see Figure 2).
___________
Kovar is an example of a suitable product available commercially. This information is given for the convenience
of users of this document and does not constitute an endorsement by IEC of this product.

– 10 – IEC 61191-3:2017 © IEC 2017
Component
Hard mount
Air
Not acceptable
Solder
IEC
Figure 2 – Hole obstruction
5.3.5.9 Metal-cased component insulation
Metal-cased components shall be insulated from adjacent electrically conductive elements.
Insulation material shall be compatible with the circuit and printed board material.
5.3.5.10 Jumper wires
Jumper wires shall conform to the applicable design specification(s) and shall be documented
on the assembly drawing.
6 Acceptance requirements
6.1 General
Materials, processes and procedures described and specified in IEC 61191-1 provide for
soldered interconnections that are better than the minimum acceptance requirements in this
clause. Processes and their controls should be capable of producing products meeting or
exceeding the acceptance criteria for a level C product.
6.2 Control and corrective actions
6.2.1 General
The detailed requirements for acceptance, corrective action limits, control limit determination
and general assembly criteria described in IEC 61191-1 are a mandatory part of this standard.
In addition, the criteria defined in Subclauses 6.2.2 to 6.3.3 shall meet the requirements for all
through-hole assembly and connection acceptability.
6.2.2 Interfacial connections (vias)
Unsupported holes with leads, or plated through-holes not subjected to mass soldering and
used for interfacial connections, need not be filled with solder. Exposed copper on via pads is
permitted. Plated through-holes that are not exposed to solder, because of permanent or
temporary maskants, and which are used for interfacial connections, need not be filled with
solder.
Plated through-holes without leads, including vias, after exposure to reflow, wave, dip, or drag
solder processing shall meet the acceptability requirements of IEC 61191-1.

6.3 Through-hole component lead soldering
6.3.1 General
The solder joint shall provide evidence of good wetting, and the plated through-hole solder fill
shall meet the requirements of Table 1 and Figures 3 and 5, with solder wetted to the hole's
wall. Single-sided boards shall meet conditions C and E of Table 1 and Figure 4.
Vertical
Solder destination
fill
side
Solder source
side
Solder
depression
IEC
Minimum acceptable for all levels as in Table 1.
Outline of the lead or wire shall be visible in the solder fillet.
Figure 3 – Through-hole component lead soldering
IEC
IEC
Levels A and B Level C
Figure 4 – Lead-to-land fillet requirements for clinched leads and
wires in non-plated through-holes

– 12 – IEC 61191-3:2017 © IEC 2017
IEC
IEC
Levels A and B Level C
Figure 5 – Lead-to-land fillet requirements for clinched leads
and wires in plated through-holes
Table 1 – Plated through-holes with component leads,
1)
minimum acceptable conditions
Criteria Level A Level B Level C
A. Circumferential wetting-solder, destination side – lead and Not specified 180° 270°
barrel
2) 3)
B. Vertical fill of solder Not specified 75 % 75 %
C. Circumferential fillet and wetting – solder source side 270° 270° 330°
D. Percentage of original land area covered with wetted solder 0 % 0 % 0 %
– solder destination side
E. Percentage of original land area covered with wetted solder 75 % 75 % 75 %
– solder source side
1)
Wetted solder refers to solder applied by the solder process.
2)
A total maximum of 25 % depression, including both solder source and destination sides, is permitted.
3)
For level B solder fill of 50% or 1.2mm, whichever is less, is acceptable when the plated hole is connected to
a heatsink layer, the lead is discernible on the solder source side, and the solder joint shows 360°
circumferential wetting of barrel and lead on the solder source side.

The connection for level A and B may have one or two fillets corresponding in length to 270°
of the overlap of the lead on the termination land.
A connection in level C shall show circumferential fillet of 330° complete. Heel of leads shall
be wetted with solder. Solder shall fill the hole in accordance with table 1.
6.3.2 Clinched leads
If a lead or wire is clinched, the lead or wire may make contact with the conductor pattern
before soldering. The outline of the lead or wire shall be visible in the solder fillet. See
Figures 4 and 5.
6.3.3 Exposed basis metal
Incomplete solder wetting at the tip of through-hole component leads, the edges and/or
periphery of printed board lands and conductors is acceptable. Exposed basis metal caused
by cutting of component leads after soldering is permissible (see 5.3.5.7).
7 Rework of unsatisfactory solder connections
Rework of unsatisfactory solder connections shall not be performed until the discrepancies
have been documented. This data shall be used to provide an indication as to possible
causes, and to determine if corrective action is required in accordance with IEC 61191-1.
When rework is performed, each reworked/or reflowed connection shall be inspected to the
requirements of 5.3 (see Table 2 for list of defects).
Table 2 – Through-hole solder joint defects
No. Defects
1 Defects identified in Table 2 of IEC 61191-1:20XX
2 Solder connections that do not meet the requirements of Table 1 exhibiting a solder fillet joining the
component lead to the land
3 Inadequate stress relief on components and wires
NOTE Solder in the stress relief bend does not constitute elimination of stress relief.

– 14 – IEC 61191-3:2017 © IEC 2017

(normative)
Placement requirements for through-hole mount devices
A.1 General
The following placement requirements for through-hole mount devices shall be imposed only if
process controls are not sufficiently in place to ensure compliance with 5.1.
A.2 Horizontal mounting, free-standing
When components are mounted free-standing, the spacing between the body of the
component or end of the meniscus (if present) and the surface of the board shall, as a
minimum, meet the cleaning requirements of the assembly or the requirements stated in 5.2.
As a maximum, the spacing should be 2,0 mm. In no instance shall non-parallelism result in
non-conformance with the minimum spacing limits (see Figure A.1).
IEC
Figure A.1 – Mounting of free-standing components
A.3 Axial lead components
Axial lead parts shall be mounted as specified on the approved assembly drawing and
mounted approximately parallel to the board surface, or perpendicular as specified in A.4.1.
Bodies of axial lead parts should be approximately centred.
A.4 Radial lead components
Radial lead components should be mounted parallel to the surface of the printed board within
the spacing tolerances specified herein.
A.5 Perpendicular mounting, free-standing
A.5.1 General
The spacing requirements for free-standing, perpendicular mounted parts shall be the same
as those for horizontal mounting (see Clause A.1).

2 mm
A.5.2 Mounting of components
Unless otherwise noted on the assembly drawing, through-hole components required to be
°
perpendicularly mounted should be installed with their major axis approximately 90 to the
board surface and with a minimum of 0,3 mm between the component body (seal or lead
weld) and the board surface.
A.5.3 Radial lead components
When dual-lead components are mounted free-standing, the larger sides should be within 15°
of perpendicular to the board surface. This requirement applies to components of
configurations shown in Figures A.2 and A.3.
IEC IEC IEC IEC IEC IEC IEC IEC IEC

Crystal Molded Water Diode Pocketbook Molded Test Orangedrop Miniature
can box capacitor capacitor box point capacitor choke
device capacitor resistor
a) b) c) d) e) f) g) h) j)
Molded Disk Diode Pocketbook Molded Test Orangedrop Choke
Crystal
capacitor capacitor capacitor Resistor point capacitor
Figure A.2 – Typical configuration of components with dual non-axial leads
No risk of shorts
IEC
Figure A.3 – Mounting of components with dual non-axial leads
A.6 Side- and end-mounting
When documented on an approved assembly drawing, a component may be either side-
mounted or end-mounted as shown in Figures A.4 and A.5. The side or surface of the body, or
at least one point of any irregularly configured component (such as certain pocketbook
capacitors) shall be in full contact with the printed board, and the body shall be bonded or
otherwise retained to the board to prevent damage when vibrational and shock forces are
applied.
≥ 0,3 mm
≥ 0,3 mm
– 16 – IEC 61191-3:2017 © IEC 2017
Resin bond
IEC
Figure A.4 – Side mounting
Resin bond
IEC
Figure A.5 – End mounting
A.7 Supported component mounting
A.7.1 General
When components are supported, they shall be mounted as follows.
When a component with resilient integral feet or a resilient integral stand-off is mounted to a
printed board, the component shall be seated with each foot in contact with the surface of the
board. For this requirement, a button stand-off as shown in Figure A.6 b) shall be deemed a
foot and the mating surface of each button shall be flat on the bare board or circuitry.
a) resilient feet or stand-offs integral to the component body (see Figures A.6 a) and A.6 b));
b) resilient or specially configurednon-resilient stand-off devices (see Figure A.6 c)); or
c) separate resilient, non-footed stand-offs which do not block plated through holes nor
conceal connections on the component side of the board.
When a component with resilient integral feet or a resilient integral stand-off is mounted to a
printed board, the component shall be seated with each foot in contact with the surface of the
board. For this requirement, a button stand-off as shown in Figure A.6 b) shall be deemed a
foot and the mating surface of each button shall be flat on the bare board or circuitry.

Lead bend
Standoff
cavity
foot
Standoff
Standoff
foot
IEC IEC IEC IEC
Dogbone coil Can device with Footed standoff Footed standoff
(footed) integral standoff
a) Dogbone coil b) Can device c) Footed Standoff d) Lead bend cavity
Figure A.6 – Mounting with footed stand-offs
A.7.2 Stand-off positioning
No stand-off shall be inverted.
A.7.3 Non-resilient footed stand-offs
When specially configured non-resilient stand-offs are used, that portion of the lead in the
lead bend cavity (see Figure A.7 b)) shall conform with an angular line extending from the
lead insertion hole in the stand-off device to the land attachment hole in the printed board.
IEC IEC
The lead is improperly formed The body is seated on the device.
in the bend cavity Each foot is in contact with the board.
Lead is properly formed in the bend cavity
a) Not acceptable condition b) Acceptable condition
Figure A.7 – Non-resilient footed stand-offs
A.8 Stress relief lead configuration
Components shall be mounted to any one, or a combination of, the following configurations:
a) in a conventional manner using 90° (nominal) lead bends directly to the mounting hole
(see Figure A.8 a));
b) with camel hump bends (see Figures A.8 b) and A.8 c)). Configuration incorporating a
single camel hump (see Figure A.8 b)) may have the body positioned off-centre;
c) other configurations may be used with an agreement of the user.

– 18 – IEC 61191-3:2017 © IEC 2017
IEC IEC IEC
Typical optional method
a) Conventional bend b) Single camel hump bend c) Double camel hump bend
Figure A.8 – Acceptable lead configurations
A.9 Flat pack lead configuration
Whether it be ribbon, flattened, or square configuration, leads of flatpacks of the normal and
butterfly configurations (leads leaving from two or more side walls) can be configured as
shown in Figure A.9.
IEC
Figure A.9 – Configuration of ribbon leads for through-hole mounting

Bibliography
IEC and ISO references
IEC 60068-2-20, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices with leads
IEC 60068-2-58, Environmental testing – Part 2-58: Tests – Test Td: Test methods for
solderability, resistance to dissolution of metallization and to soldering heat of surface
mounting devices (SMD)
IEC 61188-5-1, Printed boards and printed board assemblies – Design and use – Part 5-1:
Attachment (land/joint) considerations – Generic requirements
IEC 61188-5-2, Printed boards and printed board assemblies – Design and use – Part 5-2:
Attachment (land/joint) considerations – Discrete components
IEC 61188-5-3, Printed boards and printed board assemblies – Design and use – Part 5-3:
Attachment (land/joint) considerations – Components with gull-wing leads on two sides
IEC 61188-5-4, Printed boards and printed board assemblies – Design and use – Part 5-4:
Attachment (land/joint) considerations – Components with J leads on two sides
IEC 61188-5-5, Printed boards and printed board assemblies – Design and use – Part 5-5:
Attachment (land/joint) considerations – Components with gull-wing leads on four sides
IEC 61188-5-6, Printed boards and printed board assemblies – Design and use – Part 5-6:
Attachment (land/joint) considerations – Chip carriers with J-leads on four sides
IEC 61188-7, Printed boards and printed board assemblies – Design and use – Part 7:
Electronic component zero orientation for CAD library construction
IEC 61189-2, Test methods for electrical materials, printed boards and other interconnection
structures and assemblies – Part 2: Test methods for materials for interconnection structures
IEC 61190-1-2, Attachment materials for electronic assembly – Part 1-2: Requirements for
soldering pastes for high-quality interconnects in electronics assembly
IEC 61193-1, Quality assessment systems – Part 1: Registration and analysis of defects on
printed board assemblies
IEC 61193-3, Quality assessment systems – Part 3: Selection and use of sampling plans for
printed board and laminate end-product and in-process auditing
IEC 62326-1, Printed boards – Part 1: Generic specification
IEC 62326-4, Printed boards – Part 4: Rigid multilayer printed boards with interlayer
connections – Sectional specification
IEC 62326-4-1, Printed boards – Part 4: Rigid multilayer printed boards with interlayer
connections – Sectional specification – Section 1: Capability detail specification –
Performance levels A, B and C
IEC PAS 62326-7-1, Performance guide for single- and double-sided flexible printed wiring
boards
– 20 – IEC 61191-3:2017 © IEC 2017
ISO 9001, Quality management systems – Requirements
Other references
IPC-TM-650, Test Methods Manual
2.3.25 Detection and measurement of ionizable surface contaminants by resistivity of
solvent extract
2.3.25.1 Ionic Cleanliness Testing of Bare PWBs
2.3.27 Cleanliness test – residual rosin
2.3.38 Surface organic contamination detection test
2.4.22 Bow and twist (percentage)
2.6.3.3 Surface insulation resistance, fluxes
IPC-9191, General Requirements for Implementation of Statistical Process Control
IPC-OI-645, Standard for Visual Optical Inspection Aids
IPC-SM-817, General Requirements for Dielectric Surface Mounting Adhesives
J-STD-001, Requirements for Soldered Electrical and Electronic Assemblies
J-STD-002, Solderability Tests for Component Leads, Terminals, Lugs Terminals and Wires
J-STD-003, Solderability Tests for Printed Boards
J-STD-004, Requirements for Soldering Fluxes
J-STD-005, General Requirements and Test Methods for Electronic Grade Solder Paste
J-STD-006, General Requirements and Test Methods for Solder Alloys and Fluxed and Non-
Fluxed Solid Solders for Electronic Solder Applications
J-STD-020, Moisture/Reflow Sensitivity Classification for Nonhermetic Surface Mount Devices

_____________
– 22 – IEC 61191-3:2017 © IEC 2017
SOMMAIRE
SOMMAIRE . 22
AVANT-PROPOS . 24
1 Domaine d’application . 26
2 Références normatives . 26
3 Termes et définitions .
...