@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{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} }