Optimizing defect detection in connections of power electronics by laser speckle photometry
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Lennard Surner , Following the completion of his studies in mechanical engineering at HTW Dresden, Lennard Surner conducted research at the Fraunhofer Institute for Material and Beam Technology (IWS), with a particular focus on advanced coating technologies for corrosion and wear protection. He subsequently joined Fraunhofer IKTS as a research associate. His work there includes the development of the Laser Speckle Photometry as an innovative defect detection method for inline inspection of solder and sinter joints in power electronics.
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Lili Chen , Lili Chen received his Master of Science degree at Dresden International University in 2016. He has been working as a research associate at the Fraunhofer IKTS in Dresden since 2016. In 2021, he received his Ph.D. in electrical engineering from TU Dresden. His research interests mainly focus on the development of laser speckle photometry for material characterization and defect detection.
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Beatrice Bendjus , After her studies and PhD in the field of materials science at the TU Bergakademie Freiberg, she worked at the Fraunhofer IZFP in the field of material characterization by various microscopic methods. She moved to Fraunhofer IKTS in 2014 and is the group leader of the Speckle-Based Methods team here. Beatrice Bendjus was significantly involved in the development of the Laser Speckle Photometry.
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Gerald Gerlach , Senior Professor for Solid State Electronics, Institute for Solid State Electronics, Technical University of Dresden.
Abstract
For reliable structures in power electronics, it is crucial to guarantee the proper quality of their interconnection layers. At the moment, most of these joints are made by a solder process. Like every joining process, irregularities such as cracks or voids can impair their thermal and structural resilience. In the context of power electronics, one of the most important factors is the heat path from semiconductor devices into the substrates they are soldered onto. A disturbed heat path can, in the worst case, lead to failure of an entire (safety-relevant) system. Recent investigations have shown that the Laser Speckle Photometry (LSP) is a promising method to detect such impurities. Therefore, the specimen is illuminated by coherent monochromatic light. The interfering effects can then be recorded and analysed, since their behaviour can be correlated with the sample’s state. Additionally, due to its easy setup and its non-contact, non-destructive manner, the LSP could be well suited even for inline applications. The previous publication presented a simulation that showed the underlying physical processes and the transmission of these into a real setup, testing on synthetically provoked voids. This paper will concentrate on improving the system to analyse real samples, optimize measurement times and provide an outlook for further development steps.
Zusammenfassung
Für zuverlässige Aufbauten in der Leistungselektronik ist es von entscheidender Bedeutung, dass die Qualität von Verbindungsschichten gewährleistet ist. Gegenwärtig werden die meisten dieser Verbindungen durch ein Lötverfahren hergestellt. Wie bei jedem Fügeverfahren können Unregelmäßigkeiten wie Risse oder Hohlräume die thermische und strukturelle Belastbarkeit beeinträchtigen. Im Zusammenhang mit der Leistungselektronik ist einer der wichtigsten Faktoren der Wärmepfad von Halbleiterbauelementen in die Substrate, auf die sie gelötet sind. Ein gestörter Wärmepfad kann im schlimmsten Fall zum Ausfall eines ganzen (sicherheitsrelevanten) Systems führen. Neuere Untersuchungen haben gezeigt, dass die Laser-Speckle-Photometrie (LSP) eine vielversprechende Methode ist, um solche Fehlstellen zu erkennen. Dabei wird die Probe mit kohärentem, monochromatischem Licht beleuchtet. Die entstehenden Interferenzeffekte werden aufgezeichnet und analysiert, da ihr Verhalten mit dem Dehnungszustand der Probe, der vom Defektzustand beeinflussten Wärmepfad abhängt, korreliert werden kann. Aufgrund ihres einfachen Aufbaus und der berührungslosen, zerstörungsfreien Arbeitsweise, eignet sich die LSP auch für Inline-Anwendungen. In einer vorangegangenen Veröffentlichung wurden die zugrundeliegenden physikalischen Prozesse beschrieben und gezeigt, wie diese auf eine reale Versuchsanordnung mit synthetisch provozierten Hohlräumen übertragen werden können. Dieser Beitrag konzentriert sich nun auf die Verbesserung des Systems zur Analyse realer Proben, die Verkürzung der Messzeiten und gibt einen Ausblick auf weitere Entwicklungsschritte.
About the authors
Lennard Surner, Following the completion of his studies in mechanical engineering at HTW Dresden, Lennard Surner conducted research at the Fraunhofer Institute for Material and Beam Technology (IWS), with a particular focus on advanced coating technologies for corrosion and wear protection. He subsequently joined Fraunhofer IKTS as a research associate. His work there includes the development of the Laser Speckle Photometry as an innovative defect detection method for inline inspection of solder and sinter joints in power electronics.
Lili Chen, Lili Chen received his Master of Science degree at Dresden International University in 2016. He has been working as a research associate at the Fraunhofer IKTS in Dresden since 2016. In 2021, he received his Ph.D. in electrical engineering from TU Dresden. His research interests mainly focus on the development of laser speckle photometry for material characterization and defect detection.
Beatrice Bendjus, After her studies and PhD in the field of materials science at the TU Bergakademie Freiberg, she worked at the Fraunhofer IZFP in the field of material characterization by various microscopic methods. She moved to Fraunhofer IKTS in 2014 and is the group leader of the Speckle-Based Methods team here. Beatrice Bendjus was significantly involved in the development of the Laser Speckle Photometry.
Gerald Gerlach, Senior Professor for Solid State Electronics, Institute for Solid State Electronics, Technical University of Dresden.
Acknowledgments
The authors would like to thank the Federal Ministry of Education and Research for supporting the ‘OptiVoid’ project and their partners GÖPEL electronic, Budatec GmbH, Dresden elektronik, Danfoss Silicon Power and Siemens AG. Thanks are also due to colleagues from various institutions and the ZmP of the TU Dresden for their important contributions and support.
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: Not applicable.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: None declared.
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Research funding: Federal Ministry of Education and Research GER.
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Data availability: Not applicable.
References
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Articles in the same Issue
- Frontmatter
- Editorial
- XXXVIII. Messtechnisches Symposium des AHMT in Hall in Tirol
- Research Articles
- Review and perspectives of the force-displacement measurement system with electromagnetic and electrostatic force compensation principles
- Optimizing defect detection in connections of power electronics by laser speckle photometry
- Design methodology and uncertainty estimation of a wireless sensor network for surface strain and shape measurements
- High-resolution coherence scanning immersion interferometry for characterization of sub-micrometer surface structures
- Using laser Doppler extensometry with polarization diversity to measure strain in high-speed tensile testing
- Edge width and edge gradient: influence on accuracy when measuring areas in lossily compressed images
Articles in the same Issue
- Frontmatter
- Editorial
- XXXVIII. Messtechnisches Symposium des AHMT in Hall in Tirol
- Research Articles
- Review and perspectives of the force-displacement measurement system with electromagnetic and electrostatic force compensation principles
- Optimizing defect detection in connections of power electronics by laser speckle photometry
- Design methodology and uncertainty estimation of a wireless sensor network for surface strain and shape measurements
- High-resolution coherence scanning immersion interferometry for characterization of sub-micrometer surface structures
- Using laser Doppler extensometry with polarization diversity to measure strain in high-speed tensile testing
- Edge width and edge gradient: influence on accuracy when measuring areas in lossily compressed images
