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BSI PD IEC TR 61191-8:2021

BSI PD IEC TR 61191-8:2021

$167.15

Printed board assemblies – Voiding in solder joints of printed board assemblies for use in automotive electronic control units. Best practices

Published By Publication Date Number of Pages
BSI 2021 38
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This part of IEC 61191 gives guidelines for dealing with voiding in surface-mount solder joints of printed board assemblies for use in automotive electronics. This technical report focuses exclusively on voids in solder joints connecting packaged electronic or electromechanical components with printed boards (PBs). Voids in other solder joints (e.g. in a joint between a silicon die and a substrate within an electronic component, solder joints of through-hole components, etc.) are not considered. The technical background for the occurrence of voids in solder joints, the potential impact of voiding on printed board assembly reliability and functionality, the investigation of voiding levels in sample- and series-production by use of X-ray inspection as well as typical voiding levels in different types of solder joints are discussed. Recommendations for the control of voiding in series production are also given.

Annex A collects typical voiding levels of components and recommendations for acceptability.

PDF Catalog

PDF Pages PDF Title
2 undefined
4 CONTENTS
6 FOREWORD
8 INTRODUCTION
9 1 Scope
2 Normative references
3 Terms and definitions
10 4 Technical background of voiding in solder joints and potential impact on assembly reliability
4.1 Void categories
Figures
Figure 1 – Example of inclusion/macro void
11 Figure 2 – Example of design induced void
Figure 3 – Example of shrinkage void
12 Figure 4 – Example of planar micro voids
Figure 5 – Example of intermetallic voids
13 4.2 Void occurrence in surface-mount technology solder joints
Figure 6 – Example of pinholes
Figure 7 – Example of blowhole voids
14 Figure 8 – Theoretical model for voiding behaviour of preballed components
15 Figure 9 – Online X-ray images and trend of void level during melting phase
16 4.3 Influence of voiding on solder joint performance
4.3.1 Introductory remarks
Figure 10 – Principal influencing parameters affecting solder joint reliability
17 4.3.2 Thermomechanical reliability
18 Figure 11 – Correlation of BGA lifetime with average and maximum void levels
19 4.3.3 Mechanical reliability
Figure 12 – Correlation void level standoff chip resistor 1206 and shear force after TC
20 4.3.4 Thermal functionality
Figure 13 – Sketch of heat transfer with exposed pad solder joints
21 4.3.5 Electrical functionality
Figure 14 – Calculation of void influence within exposed pads on overall Rth
22 5 Determination of voiding levels in solder joints
5.1 Instrumentation available for investigation of voiding in solder joints
5.1.1 General
5.1.2 X-ray inspection equipment operating in two-dimensional mode
23 5.1.3 X-ray inspection equipment operating in three-dimensional mode
24 5.2 Challenges for the X-ray inspection of voiding: two case studies
5.2.1 Influence of shadowing effects on measuring reproducibility – first results for 3D X-ray inspection equipment
Figure 15 – Average voiding results for different shadowing conditions
25 5.2.2 Influence of X-ray parameters
Figure 16 – Gauge reproducibility of void measurement with different shadowing
26 5.2.3 Manual determination of voiding levels in solder joints in sample production
Figure 17 – Void measurement of BGA region with varying X-ray parameters
27 6 Recommendations for sample qualification
28 7 Recommendations for mass production
7.1 General remarks
7.2 Ramp-up quality assurance for voiding
7.3 X-ray sampling inspection
7.3.1 General
7.3.2 Control limits
7.3.3 Exceeding the control limits
29 7.4 Process control without X-ray sampling inspection
30 Annex A (informative)Types of voids and guidelines for acceptability
A.1 Types of voids – Summary
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
31 A.2 Typical voiding levels of components and guidelines for acceptability
A.2.1 General
32 A.2.2 Ball-grid array (BGA) components with collapsing balls
A.2.3 Bottom-termination components involving a lead-frame construction, as quad-flat no lead packages, dual-flat no lead packages
33 A.2.4 Exposed pads of components with gull wing solder joints as quad-flat packages
A.2.5 Transistors with thermal plane as D2PAK and TOLL (TO lead-less)
34 A.2.6 Rectangular or square end chip components (2, 3 or 5 side terminations)
A.2.7 Light-emitting diodes
A.3 Further components currently under discussion
A.4 Tabular summary
35 Table A.2 – Recommendations for acceptable minimum solder coverage or maximum void level as well as ranges for process indicators
36 Bibliography

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BSI PD IEC TR 61191-8:2021
$167.15