IEC 61191-1:2013

IEC 61191-1 ®
Edition 2.0 2013-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Printed board assemblies –
Part 1: Generic specification – Requirements for soldered electrical and
electronic assemblies using surface mount and related assembly technologies

Ensembles de cartes imprimées –
Partie 1: Spécification générique – Exigences relatives aux ensembles
électriques et électroniques brasés utilisant les techniques de montage en
surface et associées
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IEC 61191-1 ®
Edition 2.0 2013-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Printed board assemblies –
Part 1: Generic specification – Requirements for soldered electrical and

electronic assemblies using surface mount and related assembly technologies

Ensembles de cartes imprimées –

Partie 1: Spécification générique – Exigences relatives aux ensembles

électriques et électroniques brasés utilisant les techniques de montage en

surface et associées
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 31.190; 31.240 ISBN 978-2-83220-810-6

– 2 – 61191-1 © IEC:2013
CONTENTS
FOREWORD . 6

1 Scope . 8

2 Normative references . 8

3 Terms and definitions . 9

4 General requirements . 10

4.1 Order of precedence. 10

4.1.1 General remark . 10
4.1.2 Conflict . 10
4.1.3 Conformance documentation . 10
4.2 Interpretation of requirements . 10
4.3 Classification . 11
4.4 Defects and process indicators . 11
4.5 Process control requirements . 11
4.6 Requirements flowdown . 11
4.7 Physical designs . 12
4.7.1 Design requirements . 12
4.7.2 New designs . 12
4.7.3 Existing designs . 12
4.8 Visual aids . 12
4.9 Proficiency of personnel . 12
4.9.1 Design proficiency . 12
4.9.2 Manufacturing proficiency . 12
4.10 Electrostatic discharge (ESD) . 12
4.11 Facilities . 13
4.11.1 General . 13
4.11.2 Environmental controls . 13
4.11.3 Temperature and humidity . 13
4.11.4 Lighting . 13
4.11.5 Field conditions . 13
4.11.6 Clean rooms . 13
4.12 Assembly tools and equipment . 13
4.12.1 General . 13

4.12.2 Process control . 14
5 Materials requirements . 14
5.1 Overview . 14
5.2 Solder . 14
5.3 Flux . 14
5.4 Solder paste . 15
5.5 Preform solder . 15
5.6 Adhesives . 15
5.7 Cleaning agents . 15
5.7.1 General . 15
5.7.2 Cleaning agents selection . 15
5.8 Polymeric coatings . 15
5.8.1 General . 15

61191-1 © IEC:2013 – 3 –
5.8.2 Solder resists and localized maskants . 15

5.8.3 Conformal coating and encapsulants . 15

5.8.4 Spacers (permanent and temporary) . 16

5.9 Chemical strippers. 16

5.10 Heat shrinkable soldering devices . 16

6 Components and printed board requirements . 16

6.1 General . 16

6.2 Solderability . 16

6.2.1 Parts solderability . 16

6.2.2 Reconditioning . 16
6.2.3 Solderability testing of ceramic boards . 16
6.3 Solderability maintenance . 17
6.3.1 General . 17
6.3.2 Preconditioning . 17
6.3.3 Gold embrittlement of solder joints . 17
6.3.4 Tinning of non-solderable parts . 17
6.4 Solder purity maintenance . 18
6.5 Lead preparation . 18
6.5.1 General . 18
6.5.2 Lead forming . 19
6.5.3 Lead forming limits . 19
7 Assembly process requirements . 19
7.1 Overview . 19
7.2 Cleanliness . 19
7.3 Part markings and reference designations . 19
7.4 Solder connection contours . 19
7.5 Moisture traps . 19
7.6 Thermal dissipation . 20
8 Assembly soldering requirements . 20
8.1 General . 20
8.2 General . 20
8.2.1 Soldering process . 20
8.2.2 Machine maintenance . 20
8.2.3 Handling of parts . 20
8.2.4 Preheating . 20

8.2.5 Carriers . 20
8.2.6 Hold down of surface mount leads . 20
8.2.7 Heat application. 21
8.2.8 Cooling . 21
8.3 Reflow soldering . 21
8.3.1 Requirements . 21
8.3.2 Process development for reflow soldering . 21
8.3.3 Flux application . 21
8.3.4 Solder application . 21
8.4 Mechanized immersion soldering (non-reflow) . 22
8.4.1 General . 22
8.4.2 Process development for mechanized immersion soldering . 22
8.4.3 Drying/degassing . 23
8.4.4 Holding fixtures and materials . 23

– 4 – 61191-1 © IEC:2013
8.4.5 Flux application . 23

8.4.6 Solder bath . 23

8.5 Manual/hand soldering . 23

8.5.1 Requirements . 23

8.5.2 Non-reflow manual soldering . 24

8.5.3 Reflow manual soldering. 24

9 Cleanliness requirements . 25

9.1 General . 25

9.2 Equipment and material compatibility . 25

9.3 Pre-soldering cleaning . 25
9.4 Post-soldering cleaning . 25
9.4.1 General . 25
9.4.2 Ultrasonic cleaning . 25
9.5 Cleanliness verification. 26
9.5.1 General . 26
9.5.2 Visual inspection . 26
9.5.3 Testing . 26
9.6 Cleanliness criteria . 26
9.6.1 General . 26
9.6.2 Particulate matter . 26
9.6.3 Flux residues and other ionic or organic contaminants . 26
9.6.4 Cleaning option . 27
9.6.5 Test for cleanliness . 27
9.6.6 Rosin residues on cleaned board assemblies . 27
9.6.7 Ionic residues (instrument method) . 28
9.6.8 Ionic residues (manual method) . 28
9.6.9 Surface insulation resistance (SIR) . 28
9.6.10 Other contamination . 28
10 Assembly requirements . 28
10.1 General . 28
10.2 Acceptance requirements . 28
10.2.1 Process control . 28
10.2.2 Corrective action limits . 29
10.2.3 Control limit determination . 29
10.3 General assembly requirements . 29

10.3.1 Assembly integrity . 29
10.3.2 Assembly damage . 29
10.3.3 Markings. 30
10.3.4 Flatness (bow and twist) . 30
10.3.5 Solder connection . 30
10.3.6 Interfacial connections . 31
11 Coating and encapsulation . 31
11.1 Detail requirements . 31
11.2 Conformal coating . 32
11.2.1 Coating instructions . 32
11.2.2 Application . 32
11.2.3 Performance requirements. 33
11.2.4 Rework of conformal coating . 34
11.2.5 Conformal coating inspection . 34

61191-1 © IEC:2013 – 5 –
11.3 Encapsulation . 34

11.3.1 Encapsulation instructions . 34

11.3.2 Application . 34

11.3.3 Performance requirements. 34

11.3.4 Rework of encapsulant material . 34

11.3.5 Encapsulant inspection . 34

12 Rework and repair . 35

12.1 General . 35

12.2 Rework of unsatisfactory soldered electrical and electronic assemblies . 35

12.3 Repair . 36
12.4 Post rework/repair cleaning . 36
13 Product quality assurance . 37
13.1 System requirements . 37
13.2 Inspection methodology . 37
13.2.1 Verification inspection . 37
13.2.2 Visual inspection . 37
13.2.3 Sampling inspection . 38
13.3 Process control . 38
13.3.1 System details . 38
13.3.2 Defect reduction . 38
13.3.3 Variance reduction. 39
14 Other requirements . 39
14.1 Health and safety . 39
14.2 Special manufacturing requirements . 39
14.2.1 Manufacture of devices incorporating magnetic windings . 39
14.2.2 High-frequency applications . 39
14.2.3 High-voltage or high-power applications . 39
14.3 Guidance on requirement flowdown . 39
15 Ordering data . 39
Annex A (normative) Requirements for soldering tools and equipment . 41
Annex B (normative) Qualification of fluxes . 43
Annex C (normative) Quality assessment . 44
Bibliography . 46

Figure 1 – Solder contact angle . 30
Figure 2 – Solder wetting of plated through-holes without leads . 31
Figure 3 – Coating conditions . 33

Table 1 – Solder contamination limits; maximum contaminant limit (percentage by
weight) . 18
Table 2 – Electrical and electronic assembly defects . 36
Table 3 – Magnification requirements . 37

– 6 – 61191-1 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
PRINTED BOARD ASSEMBLIES –
Part 1: Generic specification –

Requirements for soldered electrical and electronic assemblies

using surface mount and related assembly technologies

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 61191-1 has been prepared by IEC technical committee 91:
Electronics assembly technology.
This second edition cancels and replaces the first edition, published in 1998, and constitutes
a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– reference standard IEC 61192-1 has been replaced by IPC-A-610;
– some of the terminology has been updated;
– references to IEC standards have been corrected;
– the use of lead-free alloys in the assembly have been added.

61191-1 © IEC:2013 – 7 –
The text of this standard is based on the following documents:

FDIS Report on voting
91/1089A/FDIS 91/1098/RVD
Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

A list of all parts of IEC 61191 series, published under the general title Printed board

assemblies can be found in the IEC website.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 8 – 61191-1 © IEC:2013
PRINTED BOARD ASSEMBLIES –
Part 1: Generic specification –

Requirements for soldered electrical and electronic assemblies

using surface mount and related assembly technologies

1 Scope
This part of IEC 61191 prescribes requirements for materials, methods and verification criteria
for producing quality soldered interconnections and assemblies using surface mount and
related assembly technologies. This part of IEC 61191 also includes recommendations for
good manufacturing processes.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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 60721-3-1, Classification of environmental conditions – Part 3: Classification of groups
of environmental parameters and their severities – Section 1: Storage
IEC 61188-1-1, Printed boards and printed board assemblies – Design and use –
Part 1-1: Generic requirements – Flatness considerations for electronic assemblies
IEC 61189-1, Test methods for electrical materials, interconnection structures and
assemblies – Part 1: General test methods and methodology
IEC 61189-3, Test methods for electrical materials, printed boards and other interconnection
structures and assemblies – Part 3: Test methods for interconnection structures (printed
boards)
IEC 61190-1-1, Attachment materials for electronic assembly – Part 1-1: Requirements for
soldering fluxes for high-quality interconnections in electronics assembly

IEC 61190-1-2, Attachment materials for electronic assembly – Part 1-2: Requirements for
soldering pastes for high-quality interconnects in electronics assembly
IEC 61190-1-3, Attachment materials for electronic assembly – Part 1-3: Requirements for
electronic grade solder alloys and fluxed and non-fluxed solid solders for electronic soldering
applications
IEC 61191-2, Printed board assemblies – Part 2: Sectional specification – Requirements for
surface mount soldered assemblies
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
61191-1 © IEC:2013 – 9 –
IEC 61249-8-8, Materials for interconnection structures – Part 8: Sectional specification set

for non-conductive films and coatings – Section 8: Temporary polymer coatings

IEC 61340-5-1, Electrostatics – Part 5-1: Protection of electronic devices from electrostatic

phenomena – General requirements

IEC/TR 61340-5-2, Electrostatics – Part 5-2: Protection of electronic devices from

electrostatic phenomena – User guide

IEC 61760-2, Surface mounting technology – Part 2: Transportation and storage conditions

of surface mounting devices (SMD) – Application guide

IPC-A-610E:2010, Acceptability of Electronic Assemblies
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60194 as well as
the following apply.
3.1
bow
deviation from flatness of a board characterized by a roughly cylindrical or spherical curvature
so that, if the product is rectangular, its four corners are in the same plane
3.2
manufacturer
assembler
individual or company responsible for the procurement of materials and components, as well
as all assembly process and verification operations necessary to ensure full compliance of
assemblies with this standard
3.3
objective evidence
documentation, agreed to between user and manufacturer
Note 1 to entry: The documentation can be in the form of a hard copy, computer data, computer algorithms, video
or other media.
3.4
process indicator
detectable anomaly, other than a defect, that is reflective of material, equipment, personnel,

process and/or workmanship variation
3.5
proficiency
capability to perform tasks in accordance with the requirements and verification procedures
detailed in this standard
3.6
shadowing
phenomenon where parts create a shadow of leads, lands, or other parts, which obstruct
heating at reflow soldering or spreading solder at flow soldering
3.7
supplier
individual or company responsible for assuring, to the manufacturer (assembler), full
compliance of components and base materials with the requirements and verification
procedures of this standard
– 10 – 61191-1 © IEC:2013
Note 1 to entry: Components include electronic, electromechanical, mechanical components, printed boards, etc.

Note 2 to entry: Base materials include solder, flux, cleaning agents, etc.)

3.8
twist
deviation of a rectangular sheet, panel or printed board that occurs parallel to a diagonal

across its surface, so that one of the corners of the sheet is not in the plane that contains the

other three corners
3.9
user
procuring authority
individual, company or agency responsible for the procurement of electrical/electronic
hardware, and having the authority to define the class of equipment and any variation or
restrictions to the requirements of this standard
EXAMPLE The originator/custodian of the contract detailing these requirements.
4 General requirements
4.1 Order of precedence
4.1.1 General remark
In the event of a conflict between the text of this standard and the applicable standard cited
herein, the text of this standard shall take precedence. However, nothing in this standard
supersedes applicable laws and regulations.
4.1.2 Conflict
In the event of conflict between the requirements of this standard and the applicable assembly
drawing(s), the applicable user approved assembly drawing(s) shall govern. In the event of
conflict between the requirements of this standard and assembly drawing(s) that has not been
approved, the differences shall be referred to the designated user activity for approval. Upon
such approval, the provisions shall be documented (by official revision notice or equivalent)
on the assembly drawings, which shall then govern.
4.1.3 Conformance documentation
Where this standard requires documentary evidence to support conformance claims, each
record shall be retained and be available for inspection for a minimum of two years from the
date of the recorded occurrence (see ISO 9001).

4.2 Interpretation of requirements
The introduction of product classification according to the levels and their end use (see 4.3)
permits the user to differentiate the performance requirements. When the user elects to
specify compliance with the mandatory requirements of this standard, the following conditions
apply:
• unless otherwise specified by the user, the word "shall" signifies that the requirements are
mandatory,
• deviations from any "shall" requirement requires written acceptance by the user, e.g., via
assembly drawing, specification or contract provision. The word “should” is used to
indicate a recommendation or guidance statement. The word “may” indicates an optional
situation. Both “should” and “may” express non-mandatory situations. “Will” is used to
express a declaration of purpose.

61191-1 © IEC:2013 – 11 –
4.3 Classification
This standard recognizes that electrical and electronic assemblies are subject to

classifications by intended end-item use. Three general end-product levels have been

established to reflect differences in producibility, functional performance requirements, and

verification (inspection/test) frequency.

It should be recognized that there may be overlaps of equipment between levels. The user

(see 3.5) of the assemblies is responsible for determining the level to which the product
belongs. The contract shall specify the level required and indicate any exceptions or

additional requirements to the parameters, where appropriate.

Level A: General electronics products
Includes consumer products, some computer and computer peripherals, and hardware
suitable for applications where the major requirement is function of the completed assembly.
Level B: Dedicated service electronics products
Includes communications equipment, sophisticated business machines, and instruments
where high performance and extended life is required, and for which uninterrupted service is
desired but not mandatory. Typically, the end-use environment would not cause failures.
Level C: High performance electronics products
Includes all equipment where continued performance or performance-on-demand is
mandatory. Equipment downtime cannot be tolerated, end-use environment may be
uncommonly harsh, and the equipment shall function when required, such as life support
systems and other critical systems.
4.4 Defects and process indicators
Table 2 lists the defects that are unacceptable and require attention (e.g., rework, repair, etc.).
The manufacturer is responsible for identifying other areas of risk and treating those
additional concerns as additions to Table 2. Such items should be documented on the
assembly drawing. Other than the unacceptable defects listed in Table 2, anomalies and
variances from "shall" requirements are considered as process indicators, and shall be
monitored when their occurrence is observed. The disposition of process indicators is not
required.
Workmanship requirements shall be consistent with IPC-A-610E, and match the level of
classification identified in 4.3.

4.5 Process control requirements
This standard requires the use of process control methodologies in the planning
implementation and evaluation of the manufacturing processes used to produce soldered
electrical and electronic assemblies. The philosophy, implementation strategies, tools and
techniques may be applied in different sequences depending on the specific company,
operation, or variable under consideration, to relate process control and capability to
end-product requirements. The manufacturer, subject to agreement by the user, may be
exempt from performing specific quality conformance evaluations and inspections, detailed in
this standard, provided objective evidence of a comprehensive and current continuous
improvement plan is available (see 13.3).
4.6 Requirements flowdown
The applicable requirements of this standard shall be imposed by each manufacturer or
supplier on all applicable subcontracts and purchase orders. The manufacturer or supplier

– 12 – 61191-1 © IEC:2013
shall not impose or allow any variation from these requirements on subcontracts or purchase

orders other than those that have been approved by the user.

Unless otherwise specified, the requirements of this standard are not imposed on the

procurement of off-the-shelf (catalogue) assemblies or subassemblies (see 14.3). However,

the manufacturer of these items may comply as deemed appropriate.

4.7 Physical designs
4.7.1 Design requirements
Some structural and layout design requirements are given in the following subclauses.

4.7.2 New designs
The printed board layout and mechanical and thermal structure of the electrical/electronic
assembly should, where relevant
...