|
IEC TR 61191-8
Edition 1.0 2021-03
TECHNICAL
REPORT
colour
inside
Printed board assemblies –
Part 8: Voiding in solder joints of printed board assemblies for use in automotive
electronic control units – Best practices
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de
CH-1211 Geneva 20
Switzerland
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 corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
.
IEC TR 61191-8
Edition 1.0 2021-03
TECHNICAL
REPORT
colour
inside
Printed board assemblies –
Part 8: Voiding in solder joints of printed board assemblies for use in automotive
electronic control units – Best practices
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.180; 31.190 ISBN 978-2-8322-9575-5
– 2 – IEC TR 61191-8:2021 IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Technical background of voiding in solder joints and potential impact on assembly
reliability . 8
4.1 Void categories . 8
4.2 Void occurrence in surface-mount technology solder joints . 11
4.3 Influence of voiding on solder joint performance . 14
4.3.1 Introductory remarks . 14
4.3.2 Thermomechanical reliability . 15
4.3.3 Mechanical reliability . 17
4.3.4 Thermal functionality . 18
4.3.5 Electrical functionality . 19
5 Determination of voiding levels in solder joints . 20
5.1 Instrumentation available for investigation of voiding in solder joints . 20
5.1.1 General . 20
5.1.2 X-ray inspection equipment operating in two-dimensional mode. 20
5.1.3 X-ray inspection equipment operating in three-dimensional mode . 21
5.2 Challenges for the X-ray inspection of voiding: two case studies . 22
5.2.1 Influence of shadowing effects on measuring reproducibility – first
results for 3D X-ray inspection equipment . 22
5.2.2 Influence of X-ray parameters . 23
5.2.3 Manual determination of voiding levels in solder joints in sample
production . 24
6 Recommendations for sample qualification . 25
7 Recommendations for mass production . 26
7.1 General remarks . 26
7.2 Ramp-up quality assurance for voiding . 26
7.3 X-ray sampling inspection . 26
7.3.1 General . 26
7.3.2 Control limits . 26
7.3.3 Exceeding the control limits . 26
7.4 Process control without X-ray sampling inspection . 27
Annex A (informative) Types of voids and guidelines for acceptability . 28
A.1 Types of voids – Summary . 28
A.2 Typical voiding levels of components and guidelines for acceptability . 29
A.2.1 General . 29
A.2.2 Ball-grid array (BGA) components with collapsing balls . 30
A.2.3 Bottom-termination components involving a lead-frame construction, as
quad-flat no lead packages, dual-flat no lead packages . 30
A.2.4 Exposed pads of components with gull wing solder joints as quad-flat
packages . 31
A.2.5 Transistors with thermal plane as D2PAK and TOLL (TO lead-less) . 31
A.2.6 Rectangular or square end chip components (2, 3 or 5 side
terminations) . 32
A.2.7 Light-emitting diodes . 32
A.3 Further components currently under discussion . 32
A.4 Tabular summary . 32
Bibliography . 34
Figure 1 – Example of inclusion/macro void . 8
Figure 2 – Example of design induced void . 9
Figure 3 – Example of shrinkage void . 9
Figure 4 – Example of planar micro voids . 10
Figure 5 – Example of intermetallic voids . 10
Figure 6 – Example of pinholes . 11
Figure 7 – Example of blowhole voids . 11
Figure 8 – Theoretical model for voiding behaviour of preballed components . 12
Figure 9 – Online X-ray images and trend of void level during melting phase . 13
Figure 10 – Principal influencing parameters affecting solder joint reliability . 14
Figure 11 – Correlation of BGA lifetime with average and maximum void levels . 16
Figure 12 – Correlation void level standoff chip resistor 1206 and shear force after TC. 17
Figure 13 – Sketch of heat transfer with exposed pad solder joints . 18
th
Figure 14 – Calculation of void influence within exposed pads on overall R . 19
Figure 15 – Average voiding results for different shadowing conditions . 22
Figure 16 – Gauge reproducibility of void measurement with different shadowing . 23
Figure 17 – Void measurement of BGA region with varying X-ray parameters . 24
Table A.1 – Types of voids with indication of root cause, occurrence in automotive
electronic assemblies, detectability, effect on thermomechanical reliability, thermal and
electrical function and overall assessment . 28
Table A.2 – Recommendations for acceptable minimum solder coverage or maximum
void level as well as ranges for process indicators . 33
– 4 – IEC TR 61191-8:2021 IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PRINTED BOARD ASSEMBLIES –
Part 8: Voiding in solder joints of printed board assemblies
for use in automotive electronic control units – Best practices
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 pos
...