@misc{PanahandehMayGrosseKockertetal., author = {Panahandeh, Sara and May, Daniel and Grosse-Kockert, Corina and Schacht, Ralph and Abo Ras, Mohamad and Wunderle, Bernhard}, title = {Pulsed infrared thermal imaging as inline quality assessment tool}, series = {Microelectronics Reliability}, volume = {2023}, journal = {Microelectronics Reliability}, number = {Volume 142}, issn = {0026-2714}, doi = {10.1016/j.microrel.2023.114910}, pages = {1 -- 11}, abstract = {Pulsed infrared thermography (PIRT) is a very fast and non-destructive technique for testing various types of specimens. This makes PIRT interesting for 100 \%-inspections in industrial production lines. Especially for the die attach interface inspection of sintered and soldered electronic components and layer-to-layer interfaces in fiber-reinforced plastic (FRP), the industry is looking for alternatives to cost intensive X-ray methods and the time-consuming scanning acoustic microscopy (C-SAM). A big challenge to use the PIRT technology for inspections in industrial production lines is the low emissivity of the surface of the device under test (DUT). This work will present a PIRT system including a vacuum foil lamination setup to avoid the necessary spray coating of DUTs with low emissivity surfaces in failure analyses. This system can be used as inline quality assessment tool with an integrated technique to perform reliable component inspections on a wide range of different specimens.}, language = {en} } @misc{SchachtMajedGruenetal., author = {Schacht, Ralph and Majed, Jihed Ben and Gr{\"u}n, Tobias and May, Daniel and Ras, Mohamad Abo and Wunderle, Bernhard}, title = {Closed-loop flow boiling cooler test stand for investigations on future power package designs}, series = {2024 30th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, journal = {2024 30th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, doi = {10.1109/THERMINIC62015.2024.10732089}, pages = {1 -- 8}, abstract = {In this work, flow boiling heat transfer to water is investigated experimentally. Flow boiling heat transfer is a topic that is of interest for the cooling of power electronics, high performance computing in automotive applications, and other electronic packages with particularly high heat flux. To investigate cooling solutions for new electronic packages a closed-loop two-phase flow boiling cooling test stand for rapid experimental characterization and parameter variation is introduced. In order to have a proof of concept for the test stand and to demonstrate comparability with the test setups described in the literature, first, different cooler structures in the mm range are investigated, using copper heater modules driven by heater cartridges. Secondly, the integration of flow boiling cooling together with an industry-oriented electronic power package is demonstrated. A heat transfer coefficient of 24 kW/m²K (242 W/cm² at 1.5 kW on a chip area of 24.9 x 24.9 mm²) was achieved for a plain silicon chip surface at a volume flow rate of 1 l/min using dielectric water as cooling fluid. The chip temperature and the differential pressure were measured to 137 °C and 8 kPa.}, language = {en} } @misc{WiedemannLammSchacht, author = {Wiedemann, Gregor and Lamm, Tino and Schacht, Ralph}, title = {Transient electro-thermal characterisation at systemlevel for an Easypack-IGBT-Module - Reduced order modelling (ROM) and junction temperature evaluation based on the onstate resistance}, series = {2024 30th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, journal = {2024 30th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, doi = {10.1109/THERMINIC62015.2024.10732700}, pages = {1 -- 8}, abstract = {This paper presents an approach for the creation of SPICE behavioral models for an IGBT and the reverse diode on a datasheet basis which explicitly describes the transient electro-thermal behavior with a closed function expression using the example of the Infineon FS25R12W1T7 IGBT module. The rapid convergence achieved in this way results in considerably shorter calculation times for an overall simulation at system level compared to an IGBT model consisting of several components (MOSFET, BJT). The validation of the simulation results is carried out in a drive application in order to obtain realistic conditions. The applied method for junction temperature estimation is based on a thermosensitive electrical parameter (TSEP) and extends the online VCEsat(T) measurement method. The onstate resistance is used as the TSEP, which on the one hand leads to a universal measurement method, but on the one hand also to a nonlinearity between temperature and TSEP on the other - Ron(T, VGE, IC). With the help of an algorithm, that has stored the calibration data in functions and applies an optimized multi-stage curve fitting, the back calculation and thus the determination of the junction temperature is made possible.}, language = {en} } @inproceedings{SchachtMajedGruenetal., author = {Schacht, Ralph and Majed, Ben and Gruen, Tobias and May, Daniel and Wunderle, Bernhard}, title = {Multi-purpose thermal test vehicle for experimental investigation on pumped two-phase cooling}, series = {2024 25th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}, booktitle = {2024 25th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}, publisher = {IEEE}, doi = {10.1109/EuroSimE60745.2024.10491533}, pages = {1 -- 7}, abstract = {Flow boiling heat transfer to water of different cooler surface topologies is experimentally investigated. To have the possibility for investigations of new electronic packages that supports cooling solutions by two-phase flow boiling, a multipurpose closed two-phase flow boiling cooling test stand for rapid experimental characterization and parameter variation is designed. The designed test vehicle holds interchangeable, plug-in heating module that offers the possibility to investigate different cooler structures and surface topologies/chemistry to improve the formation and release of small bubbles. In order to have a proof of concept for the test stand and to show its reproducible to those given in the literature, initially, the investigation is limited to a plain-and dimpled-surface and a pin fin and finned cooler structure in the mm range.}, language = {en} } @misc{MajedSchachtFischeretal., author = {Majed, Jihed Ben and Schacht, Ralph and Fischer, Tim and Zajaczkowski, Marek and May, Daniel and Pareek, Kaushal Arun and Zafar, Syed Ali}, title = {Anwendung der Lock-in-Thermographie zur Defekterkennung in additiv gefertigten AMC Schweißn{\"a}hten}, series = {DGZfP 2025 : DGZfP-Jahrestagung 2025, 26.-28. Mai 2025 in Berlin}, journal = {DGZfP 2025 : DGZfP-Jahrestagung 2025, 26.-28. Mai 2025 in Berlin}, publisher = {DGZfP}, address = {Berlin}, doi = {https://doi.org/10.58286/31221}, pages = {1 -- 10}, abstract = {Additiv gefertigte Aluminium-Matrix-Composite (AMC)-Materialien bieten durch ihr geringes Gewicht und ihre hohe Festigkeit signifikante Vorteile, f{\"u}hren aber w{\"a}hrend des Schweißvorgangs zu Porenbildung die die Festigkeit beeinflussen. Im Rahmen der F{\"o}rderbekanntmachung „WIR! - Wandel durch Innovation in der Region" des Bundesministeriums f{\"u}r Bildung und Forschung (BMBF) wird im Teilvorhaben „Inline-Prozesskettenentwicklung zum Reparieren von AMC-Werkstoffen sowie Porendetektion mittels aktiver IR-Thermographie zur Prozess{\"u}berwachung" eine Machbarkeitsstudie zur Nutzung der Lock-in-Thermographie (LIT) zur Defekterkennung in AMC-Schweißn{\"a}hten durchgef{\"u}hrt. Ziel der Machbarkeitsstudie ist es, die Anwendbarkeit der LIT f{\"u}r die Inline-Prozess{\"u}berwachung dieses Werkstoffs zu bewerten, da dessen thermische und mechanische Eigenschaften, darunter eine thermische Diffusivit{\"a}t von etwa 8,6 * 1E-5 m²/s, besondere Herausforderungen f{\"u}r die zerst{\"o}rungsfreie Pr{\"u}fung (ZfP) darstellen. Die LIT, bei der eine modulierte W{\"a}rmequelle verwendet wird, erlaubt die Erkennung von ‚subsurface' Defekten durch die Analyse der thermischen Wellen. Es werden verschiedene Algorithmen eingesetzt, um die thermischen Daten zu analysieren und die thermische Empfindlichkeit der verwendeten Kamera zu simulieren. Neben den experimentellen Untersuchungen werden FEM-Simulationen genutzt, um optimale Betriebsparameter wie Modulationsfrequenz und notwendige Laserleistung zu bestimmen. So konnten bereits zuverl{\"a}ssig Defekte ab 2 mm Gr{\"o}ße bis zu 1,5 mm Tiefe unter der Oberfl{\"a}che detektiert werden. Die FE-Simulationsergebnisse zeigen zudem, dass durch Anpassungen der Anregungsfrequenz sowie weiterer Parameter wie Energieeintrag, Kamerasensitivit{\"a}t und Auswertemethoden auch kleinere, tiefer liegende Defekte erkannt werden k{\"o}nnen. Die ersten Ergebnisse zeigen, dass die LIT auch f{\"u}r additiv gefertigte Metalllegierungen f{\"u}r die pr{\"a}zise Identifizierung verborgener Defekte einsetzbar ist und somit In-line zur Steigerung der Produktionssicherheit sowie der Produktqualit{\"a}t beitragen.}, language = {de} } @misc{SchachtMajedGruenetal., author = {Schacht, Ralph and Majed, Jihed Ben and Gr{\"u}n, Tobias and May, Daniel and Ras, Mohamad Abo and Wunderle, Bernhard}, title = {Integration of two-phase flow boiling in future power packages}, series = {2025 41st Semiconductor Thermal Measurement, Modeling \& Management Symposium (SEMI-THERM)}, journal = {2025 41st Semiconductor Thermal Measurement, Modeling \& Management Symposium (SEMI-THERM)}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-7355325-5-4}, pages = {7 -- 12}, abstract = {Flow boiling heat transfer is a topic that is of interest for the cooling of power electronics, highperformance computing in automotive applications, and other electronic packages with particularly high heat flux. Based on the investigations from [Schacht 2024], in which the effects on the high performance computing (HTC) with regard to the wetting behavior of de-ionised water (DI water) on silicon (SI) and gold (Au) surfaces during two-phase flow boiling were investigated, an initial design for the integration of two-phase cooling together with the power electronics in one housing (e.g. HPC or automotive) was introduced and the requirements for a controlled two-phase cooling system were discussed. In this paper, the use of a Glycol-DI water mixture instead of DI water as a coolant is experimentally investigated with regard to heat transfer performance. In addition, the influence of the surface properties of matte and polished silicon on the heat transfer coefficient performance is investigated. Glycol-DI-water mixture is used as a coolant in applications where ambient temperatures can be below 0°C (e.g. in the automotive industry) and which has no negative impact on global warming and is explosion-proof in useWith Glycol-DI-water mixture as coolant a maximum heat transfer coefficient HTC ~ 4.4 kW (m2K) at a volume flow rate of 𝒗􁈶 = 0.5 l/min (Tin = 60°C) with a maximum wall heat flux of 𝒒􁈶 𝒘𝒂𝒍𝒍 ~ 38 W/cm² and a wall temperature of Twall ~ 165°C could be achieved. An influence between matte and polished silicon surfaces on the heat transfer could not be determined.}, language = {de} } @misc{WuPareekMayetal., author = {Wu, Yanan and Pareek, Kaushal Arun and May, Daniel and Zajaczkowski, Marek and Grosse-Kockert, Corinna and Ras, Mohamad Abo and Schacht, Ralph and Wunderle, Bernhard}, title = {Failure analysis for electronic packaging materials : a comparative study of pulsed thermography and lock-in thermography}, series = {31st International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, journal = {31st International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {979-8-3315-9486-2}, doi = {10.1109/THERMINIC65879.2025.11216883}, pages = {1 -- 6}, abstract = {Electronic packaging plays a critical role in ensuring the reliability and performance of electronic systems. As various materials are used in these systems, each with distinct properties, failure analysis of each is key to improving overall system reliability. This paper presents a comparative study of two non-destructive testing (NDT) methods—pulsed thermography (PT) and lock-in thermography (LIT) — for failure analysis in electronic packaging materials. The study focuses on defect detection in copper (Cu), aluminum (AI), and polymer, which are widely used in electronic packaging due to their distinct thermal characteristics. Experimental results are evaluated using signal-to-background contrast (SBC). To enhance thermal contrast, three post-processing techniques—pulse phase thermography (PPT), principal component thermography (PCT), and thermographic signal reconstruction (TSR)—were applied to the PT results. These results were then compared with the optimal performance of LIT. The findings demonstrate that both methods have distinct advantages and limitations: PT offers faster detection, while LIT provides higher sensitivity for materials with higher thermal diffusivity. This study enhances the understanding of how these techniques can be effectively applied in electronic packaging failure analysis.}, language = {de} }