IEC TR 60068-3-15:2024

IEC TR 60068-3-15 ®
Edition 1.0 2024-02
TECHNICAL
REPORT
colour
inside
Environmental testing –
Part 3-15: Supporting documentation and guidance – Vacuum-assisted reflow
soldering
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IEC TR 60068-3-15 ®
Edition 1.0 2024-02
TECHNICAL
REPORT
colour
inside
Environmental testing –
Part 3-15: Supporting documentation and guidance – Vacuum-assisted reflow

soldering
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.040; 31.190 ISBN 978-2-8322-8169-7

– 2 – IEC TR 60068-3-15:2024 © IEC 2024
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Voids in solder joints . 7
4.1 Type of voids . 7
4.2 Reasons for voids . 8
4.3 Influence of voiding on solder joint performance . 9
5 Vacuum-assisted soldering processes . 9
5.1 Purpose . 9
5.2 Combination of soldering process with vacuum . 9
5.3 Typical temperature-pressure-time curves . 10
5.3.1 Convection soldering with vacuum . 10
5.3.2 Vapour phase soldering with vacuum . 11
5.3.3 Contact soldering with vacuum . 12
6 Effect of vacuum when reflow soldering . 13
6.1 General . 13
6.1.1 General description . 13
6.1.2 Physical basics . 13
6.1.3 Vacuum parameters . 14
6.1.4 Vapour phase vacuum reflow soldering . 14
6.2 Components in the vacuum reflow soldering process . 15
6.2.1 Influence of pressure differences . 15
6.2.2 Influence of temperature, time, and vacuum . 18
7 Vacuum equipment restrictions . 18
7.1 General . 18
7.2 Chamber size . 18
7.3 Time to reach vacuum level . 19
7.4 Cycle time . 19
7.5 Summary . 19
8 Typical defects after vacuum-assisted reflow soldering . 20
8.1 Typical defect modes occurring at components . 20
8.2 Component defect modes – summary . 24
8.3 Soldering defect modes . 24
8.3.1 Dropping of components . 24
8.3.2 Bridging . 25
8.3.3 Splattering . 25
Bibliography . 27

Figure 1 – X-Ray examples of voids in solder joints in different SMD-Components . 8
Figure 2 – Reduction of voids with low flux soldering & preforms . 8
Figure 3 – Example of a product for vacuum-assisted soldering processes . 10
Figure 4 – Typical profile – vacuum-assisted convection soldering . 11
Figure 5 – Typical profile – vacuum-assisted vapour phase soldering . 12

Figure 6 – Typical profile – vacuum-assisted contact soldering . 13
Figure 7 – Vapour pressure curve of Galden® . 15
Figure 8 – Pressures to be considered . 16
Figure 9 – Vapour pressure curve of water . 17
Figure 10 – Blow Hole Void in/out of metallization . 20
Figure 11 – Gas bubbles at metallization interface . 20
Figure 12 – Gas bubble caused by residues in metallization defect . 21
Figure 13 – Blow out void in solder meniscus . 21
Figure 14 – Aluminium electrolytic capacitors with non-solid electrolyte, bulged . 22
Figure 15 – Composite housing bursts in case of overpressure . 22
Figure 16 – Housing mainly made of plastic bursts in case of overpressure . 23
Figure 17 – Relay lock (polymer dot) blown off. 23
Figure 18 – Housing with adhesive joint bursts in case of overpressure . 24
Figure 19 – An example of bridging on BGA during vacuum assisted soldering . 25
Figure 20 – Optimization with stepwise applying of vacuum to reduce bridging . 25
Figure 21 – Splattering due to explosive outgassing from the solder joint . 26

Table 1 – Combination of soldering processes with vacuum . 10
Table 2 – Molar mass . 17
Table 3 – Combination of soldering processes with vacuum . 19

– 4 – IEC TR 60068-3-15:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 3-15: Supporting documentation and guidance –
Vacuum-assisted reflow soldering

FOREWORD
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IEC TR 60068-3-15 has been prepared by technical committee 91: Electronics assembly
technology. It is a Technical Report.
The
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