@inproceedings{SchachtPunchMertenetal., author = {Schacht, Ralph and Punch, Jeff and Merten, Enrico and Rzepka, Sven and Michel, Bernd}, title = {Thermo-fluidisch experimentelle Untersuchung sowie CFD-Simulation f{\"u}r eine Leiterplatte mit Flip-Chip Aufbauten im Windkanal}, series = {Elektronische Baugruppen und Leiterplatten, EBL 2016, multifunktionale Baugruppen - Leistungsdichte am Limit?, 8. DVS/GMM-Tagung vom 16.-17. Februar 2016 in Fellbach}, booktitle = {Elektronische Baugruppen und Leiterplatten, EBL 2016, multifunktionale Baugruppen - Leistungsdichte am Limit?, 8. DVS/GMM-Tagung vom 16.-17. Februar 2016 in Fellbach}, publisher = {VDE Verlag}, address = {Berlin-Offenbach}, isbn = {978-3-8007-4147-2}, pages = {267 -- 272}, abstract = {Die Konzentration von elektronischen und mechanischen Komponenten auf einer Leiterplatte (z.B. Main board) nimmt st{\"a}ndig zu. Dies f{\"u}hrt zu h{\"o}heren Verlustleistungsdichten und somit zu strengeren Anforderungen an das thermische Management. In momentanen und zuk{\"u}nftigen luftgek{\"u}hlten Anwendungen wird, neben der reinen konduktiven Interaktion zwischen elektronischen Komponenten {\"u}ber die Leiterplatte, zuk{\"u}nftig auch die fluidische Interaktion der nat{\"u}rlichen und forcierten Konvektion w{\"a}hrend des Leiterplattendesigns mit zu ber{\"u}cksichtigen sein. Der Schaltkreisentwickler ben{\"o}tigt hier zus{\"a}tzliche Informationen {\"u}ber die thermo-fluidisch gekoppelten Einfl{\"u}sse zwischen den kritischen w{\"a}rmedissipierenden Komponenten sowie fluidischer {\"U}berlagerungen in Folge anderer angrenzender Komponenten oder mechanischer Komponentengeh{\"a}use. In der Vergangenheit wurden zahlreiche Benchmark-Studien zu konvektiven und konduktiven thermischen Interaktionen f{\"u}r verschiedene kommerziell erh{\"a}ltliche mikroelektrische Geh{\"a}usetypen ver{\"o}ffentlicht. Heutzutage hat sich die Flip-Chip (FC) Aufbautechnologie von ungeh{\"a}usten Chips (bare dies) etabliert. Von daher besteht der Bedarf f{\"u}r eine thermische Benchmark Studie f{\"u}r FC Aufbauten. Die vorliegende Studie untersucht die nat{\"u}rlichen und forcierten thermo-fluidischen Einfl{\"u}sse zwischen ungeh{\"a}usten FC's und anderen Komponenten, welche auf mehreren Testleiterplattendesigns aufgebaut und mit der CFD-Simulation verglichen wurden. Ein Vergleich der ersten analysierten Scenarios zeigt eine nachvollziehbare {\"U}bereinstimmung zwischen den experimentellen und den Simulationsergebnissen.}, language = {de} } @inproceedings{SchachtRzepkaDeodatetal., author = {Schacht, Ralph and Rzepka, Sven and Deodat, Andreas and Michel, Bernd}, title = {Parametrisches transientes thermo-elektrisches PSPICE Modell f{\"u}r ein zwei-adriges Stromkabel}, series = {Elektronische Baugruppen und Leiterplatten, EBL 2016, multifunktionale Baugruppen - Leistungsdichte am Limit?, 8. DVS/GMM-Tagung vom 16.-17. Februar 2016 in Fellbach}, booktitle = {Elektronische Baugruppen und Leiterplatten, EBL 2016, multifunktionale Baugruppen - Leistungsdichte am Limit?, 8. DVS/GMM-Tagung vom 16.-17. Februar 2016 in Fellbach}, publisher = {VDE Verlag}, address = {Berlin-Offenbach}, isbn = {978-3-8007-4147-2}, pages = {294 -- 298}, abstract = {Aufbauend auf dem bereits einf{\"u}hrten transienten thermo-elektrisch gekoppelten Makromodell f{\"u}r ein ein-adriges Stromkabel wird die Adaption auf ein zwei-adriges Stromkabel, sowie deren Verifikation mittels Experiment und einer Finite-Elemente-Simulation vorgestellt. Das parametrische Makromodell ist f{\"u}r den Einsatz in einem Schaltungssimulator wie z.B. PSPICE geeignet. Die Verifikation der statischen und transienten Simulationsergebnisse zwischen ANSYS, PSPICE und Experiment zeigen, je nach den {\"a}ußeren Randbedingungen eine gute {\"U}bereinstimmung. Sowohl mit dem ein-adrigen als auch dem erweiterten zwei-adrigen Makromodell ist es m{\"o}glich, auf Systemebene schnell f{\"u}r verschiedene thermische Randbedingungen und Kabelgeometrien zu modellieren und somit eine zeitsparende, transient gekoppelte thermo-elektrische Simulation je nach den Randbedingungen des Einbauorts durchzuf{\"u}hren. Hierbei unterst{\"u}tzt die parametrische Modellierung eine Beschreibung der "realen thermischen" Montagebedingungen (z.B. in einem Auto - Motorraum, Fahrzeuginnenraum). Es erm{\"o}glicht dem Entwickler sich einen schnellen {\"U}berblick {\"u}ber die thermischen Einfl{\"u}sse und Temperaturen entlang des Stromkabels zu verschaffen und so z.B. bei der Kabelauslegung hinsichtlich Gr{\"o}ße und Gewicht (Kupfer Durchmesser, verwendetes Isoliermaterial) sowie dem Einbauort (W{\"a}rmeleitung, Konvektion, Strahlung) dieses zu optimieren.}, language = {de} } @misc{NowakSchacht, author = {Nowak, Torsten and Schacht, Ralph}, title = {Coupling Effects during Thermo-Fluidic Analysis of Flip-Chip Devices with Peripheral Components - CFD Simulation and Experimental Study}, abstract = {The amount and concentration of electronic components and passive objects on board level increases rapidly. Furthermore, the complexity between conductive heat spreading and the use of forced thermo-fluidic coupling effects with application near behavior will become a challenge to prevent thermal bottlenecks during layout processing. For printed circuit board (PCB) designer, it would be helpful to consider the estimation of real thermal behavior without time consuming CFD analysis. A thermo-fluidic correction factor according to thermal resistance which should be a function of air velocity, power loss, and distance between active or passive components as well as the dimensions of electronic parts could help thermal engineers during layout process. Backwards, results were published for several benchmark studies with the investigation on convective and conductive interaction on commercially available microelectronic packages. Today, Flip-Chip (FC) assembly process of bare dies become being more up-to-date. A new investigation started to figure out interactions between natural and forced thermo-fluidic behavior of bare FC dies and near different components, mounted on a test PCB. To generate first rough estimations of the real fluid situation behavior current CFD modelling and simulation software are used. A suitable agreement between CFD simulation results and experimental analysis will be presented.}, language = {en} } @inproceedings{Schacht, author = {Schacht, Ralph}, title = {Miniaturisierter reibungsloser Lamellenl{\"u}fter}, series = {Deutsche IMAPS Konferenz, IMAPS Herbstkonferenz, M{\"u}nchen, Oktober 2016}, booktitle = {Deutsche IMAPS Konferenz, IMAPS Herbstkonferenz, M{\"u}nchen, Oktober 2016}, publisher = {IMAPS-Deutschland e.V.}, address = {Schmalkalden}, abstract = {Kommerziell verf{\"u}gbare miniaturisierte Axial- oder Radial-L{\"u}fterkonzepte basieren auf einem kugelgelagerten Prinzip, welche, aufgrund von Reibung sich abnutzen und somit eine relativ geringe Lebensdauer (MTTF < 14000 h) haben. Die am Markt verf{\"u}gbaren reibungslosen L{\"u}fterkonzepte wie Piezo-L{\"u}fter (Nutzung des Piezo-elektrischer Effektes) oder Synthetic-Jet L{\"u}fter (Lautsprecherprinzip) weisen, aufgrund des Aufbaukonzepts, eine geringere Alterung auf. Im Fall des Piezo L{\"u}fter-Lamellen-Konzepts wird die MTTF mit > 4600h angegeben, da es im Betrieb zu einer Degradation der Klebeschicht zwischen Lamelle und Piezo-Material kommt. Hinzu kommt, dass das Piezo-Element mit einer Betriebsspannung von > 40 V angeregt werden muss und der Anschaffungspreis, im Vergleich zu den miniaturisierten Axial- und Radiall{\"u}ftern als auch den Synthetic Jet L{\"u}ftern um den Faktor sechs (~ 200 €) h{\"o}her liegt. Synthetic Jet L{\"u}fter haben zwar eine wesentliche bessere MTTF > 100000 h, allerdings liegen der Formfaktor ({\O} 60 mm) und das Gewicht (125 g), verglichen mit dem Piezo L{\"u}fter (60x 15x 30 mm², 10 g, ohne Ansteuerelektronik), wesentlich dar{\"u}ber. Der Ansatz des entwickelnden reibungslosen Lamellen-L{\"u}fterkonzepts greift die Vorteile eines Piezo-L{\"u}fters (Lamelle) und des Synthetic Jet-L{\"u}fters (magnetische Anregung) auf. Dadurch, dass die Lamelle nicht mehr, wie beim Piezo-L{\"u}fter, auf einen Piezo-Aktuator aufgeklebt wird, sondern in einem K{\"o}rper fixiert und ber{\"u}hrungslos angeregt wird, verspricht das Konzept eine wesentlich h{\"o}here Lebensdauer. Anwendungen finden sich im Bereich von schwer zug{\"a}nglichen elektronischen Baugruppengeh{\"a}usen (z.B. Funkstationen), in welchen die nat{\"u}rliche Konvektion durch eine zuverl{\"a}ssige Umw{\"a}lzung der Luft erg{\"a}nzt werden soll, um die Lebensdauer der elektronischen Komponenten zu erh{\"o}hen. Im Vortrag werden das L{\"u}fterkonzept, ein miniaturisierter Prototyp (Gr{\"o}ße einer Streichholzschachtel) sowie die Performance zur K{\"u}hlung von elektronischen Komponenten an einem Anwendungsbeispiel vorgestellt.}, language = {de} } @inproceedings{SchachtPunchMertenetal., author = {Schacht, Ralph and Punch, Jeff and Merten, Enrico and Rzepka, Sven and Michel, Bernd}, title = {Thermo-fluidisch gekoppelte Untersuchung von Flip-Chips auf einer Leiterplatte}, series = {Elektronische Baugruppen und Leiterplatten EBL 2016, 8. DVS/GMM-Tagung vom 16.-17. Februar 2016 in Fellbach}, booktitle = {Elektronische Baugruppen und Leiterplatten EBL 2016, 8. DVS/GMM-Tagung vom 16.-17. Februar 2016 in Fellbach}, editor = {Schacht, Ralph}, publisher = {VDE Verlag}, address = {Berlin, Offenbach}, isbn = {978-3-8007-4147-2}, pages = {267 -- 272}, abstract = {Die Konzentration von elektronischen und mechanischen Komponenten auf einer Leiterplatte (z.B. Main board) nimmt st{\"a}ndig zu. Dies f{\"u}hrt zu h{\"o}heren Verlustleistungsdichten und somit zu strengeren Anforderungen an das thermische Management. In momentanen und zuk{\"u}nftigen luftgek{\"u}hlten Anwendungen wird, neben der reinen konduktiven Interaktion zwischen elektronischen Komponenten {\"u}ber die Leiterplatte, zuk{\"u}nftig auch die fluidische Interaktion der nat{\"u}rlichen und forcierten Konvektion w{\"a}hrend des Leiterplattendesigns mit zu ber{\"u}cksichtigen sein. Der Schaltkreisentwickler ben{\"o}tigt hier zus{\"a}tzliche Informationen {\"u}ber die thermo-fluidisch gekoppelten Einfl{\"u}sse zwischen den kritischen w{\"a}rmedissipierenden Komponenten sowie fluidischer {\"U}berlagerungen in Folge anderer angrenzender Komponenten oder mechanischer Komponentengeh{\"a}use. In der Vergangenheit wurden zahlreiche Benchmark-Studien zu konvektiven und konduktiven thermischen Interaktionen f{\"u}r verschiedene kommerziell erh{\"a}ltliche mikroelektrische Geh{\"a}usetypen ver{\"o}ffentlicht. Heutzutage hat sich die Flip-Chip (FC) Aufbautechnologie von ungeh{\"a}usten Chips (bare dies) etabliert. Von daher besteht der Bedarf f{\"u}r eine thermische Benchmark Studie f{\"u}r FC Aufbauten. Die vorliegende Studie untersucht die nat{\"u}rlichen und forcierten thermo-fluidischen Einfl{\"u}sse zwischen ungeh{\"a}usten FC's und anderen Komponenten, welche auf mehreren Testleiterplattendesigns aufgebaut und mit der CFD-Simulation verglichen wurden. Ein Vergleich der ersten analysierten Scenarios zeigt eine nachvollziehbare {\"U}bereinstimmung zwischen den experimentellen und den Simulationsergebnissen.}, language = {de} } @inproceedings{MayFritscheCardosoetal., author = {May, Daniel and Fritsche, S. and Cardoso, A. and Schacht, Ralph and Wunderle, Bernhard}, title = {IR Pulse Thermography as Failure Analytical Tool Applied to Die Attach Processes}, series = {21st International Workshop on Thermal Investigations of ICs and Systems, Sept. 30 2015 - Oct. 2 2015}, booktitle = {21st International Workshop on Thermal Investigations of ICs and Systems, Sept. 30 2015 - Oct. 2 2015}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-9705-6}, abstract = {New die attach technologies are necessary to meet the demand for faster and more reliable power electronic devices.Technologies based on sintering such as silver sintering and silver sinter adhesives are currently in the focus of technology development because of their high strength and very high thermal performance. To ensure the reliability of such a die attach reliable, fast and non-destructive failure analysis (FA) are needed. Transient thermal methods (TTM) provide techniques for detection of different types of defects such as delaminations of interfaces, cracks , electrical short circuits and voids in die attach layer [1]-[3]. In this work, pulse thermography (PT), one of the TTMs, was successfully used for nondestructive testing of the die attach layers under industrial conditions. We have studied the physical principles and presented fundamental possibilities and limitations given by formulas, nomograms and parameter sensitivity studies. Finally, we demonstrate the PT as accompanying FA to process qualification of a sintered silver adhesive process.}, language = {en} } @inproceedings{AboRasMaySchachtetal., author = {Abo Ras, Mohamad and May, Daniel and Schacht, Ralph and Bast, M. and Eisle, R. and Michel, Bernd and Winkler, Thomas and Rzepka, Sven and Wunderle, Bernhard}, title = {"LaTIMA" an Innovative Test Stand for Thermal and Electrical Characterization of Highly Conductive Metals, Die Attach, and Substrate Materials}, series = {21st International Workshop on Thermal Investigations of ICs and Systems, Sept. 30 2015 - Oct. 2 2015}, booktitle = {21st International Workshop on Thermal Investigations of ICs and Systems, Sept. 30 2015 - Oct. 2 2015}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-9705-6}, pages = {6}, abstract = {This paper deals with the development of an innovative test stand for the measurement of thermal and electrical conductivity of metals, semiconductors, highly conductive die attaches and substrates using the steady state technique for thermal characterization and four-terminal sensing with pulse delta technique for electrical characterization. We present a systematic study of sintered silver in order to investigate the influence of sintering conditions on thermal and electrical properties. Several sintered silver samples have been prepared under sintering temperature variation between 200°C and 270°C and sintering pressure variation between 5 MPa and 25 MPa. The characterization results diversify up to 200\% for thermal conductivity and up to 330\% for electrical conductivity. The Wiedemann-France law describes the relationship between electrical and thermal conductivities for bulk metals. We proved that this law applies not only for bulk metal but also for porous sintered metal.}, language = {en} } @misc{SchachtHausdorfWunderle, author = {Schacht, Ralph and Hausdorf, Alexander and Wunderle, Bernhard}, title = {Feasibility and Design Study of a Frictionless Air Mover for Thermal Management of Electronics}, series = {Journal of Physics: Conference Series}, volume = {525}, journal = {Journal of Physics: Conference Series}, issn = {1742-6596}, doi = {10.1088/1742-6596/525/1/012026}, pages = {012026}, abstract = {A frictionless air mover concept will be introduced. As opposed to a piezoelectric driven fan, the air mover is based on a flexible blade whose vibration is driven by means of a magnetic field. The blade material is based on a polymer material. The paper presents the results of feasibility and an on-going comprehensive design study. The results are compared with a comparable piezoelectric fan [1, 2]. The performance of the feasibility study amounted to 65\% to the piezoelectric fan. To enhance the performance, two different blade materials as well as the influence of the coil shape and value were under investigation. A further goal is to reduce the size and to investigate the influence of a cabinet. The design study results in a prototype of a size of 50 x 14 x 35 mm² incl. a cabinet. The performance could be doubled. A volume flow rate of V̊ ~14 l/min and static pressure of Ƿstat = 3 Pa could be reached.}, language = {en} } @misc{SparrHausdorfJeskeetal., author = {Sparr, Holger and Hausdorf, Alexander and Jeske, Peter and Kale, Nachiket and Schacht, Ralph and Ziegenhorn, Matthias and Zysk, Oliver}, title = {±270 VDC Aircraft Harness Structural Analysis}, series = {Procedia Engineering}, volume = {114}, journal = {Procedia Engineering}, issn = {1877-7058}, doi = {10.1016/j.proeng.2015.08.078}, pages = {346 -- 353}, abstract = {This research focuses on the structural analysis of aircraft electrical harnesses for the 270 VDC network. A combined experimental and simulation-based approach is used, where numerical models for the harnesses are developed and experimental data are acquired for basic test cases (steady load, pendulum test, etc.) as well as for different vibration load cases. Validation of the numerical models is done using the preliminary experimental data, resulting in a mature refined model in order to simulate complex scenarios. The goal of the project is thus to develop a suite of tools that allows detailed structural analysis of the aircraft harnesses, both stand alone as well as in combination with other systems}, language = {en} } @inproceedings{SchachtPunchMertenetal., author = {Schacht, Ralph and Punch, Jeff and Merten, Enrico and Rzepka, Sven and Michel, Bernd}, title = {Thermo-Fluidic Coupled Analysis of Flip-Chip Mounted Thermal Test Chips on a PCB - a Numerical and Experimental Study}, series = {21st International Workshop on Thermal Investigations of ICs and Systems}, booktitle = {21st International Workshop on Thermal Investigations of ICs and Systems}, editor = {Schacht, Ralph}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-9705-6}, abstract = {CFD Analysis of Flip-Chip Mounted Devices on PCB - A Numerical and Experimental Study}, language = {en} } @inproceedings{SchachtRzepkaMichel, author = {Schacht, Ralph and Rzepka, Sven and Michel, Bernd}, title = {Parametrisches transientes thermo-elektrisches PSPICE Modell f{\"u}r ein Stromkabel}, series = {AME - Automotive meets electronics, Beitr{\"a}ge der 5. GMM-Fachtagung vom 18. bis 19. Februar 2014 in Dortmund}, booktitle = {AME - Automotive meets electronics, Beitr{\"a}ge der 5. GMM-Fachtagung vom 18. bis 19. Februar 2014 in Dortmund}, editor = {Wahl, Michael}, publisher = {VDE Verlag}, address = {Berlin [u.a.]}, isbn = {978-3-8007-3580-8}, pages = {112 -- 116}, abstract = {F{\"u}r ein zun{\"a}chst einadriges Stromkabel wird ein transientes thermo-elektrisch gekoppeltes Makromodell sowie deren Verifikation mittels Experiment und einer Finite-Elemente-Simulation vorgestellt. Das parametrische Makromodell ist f{\"u}r den Einsatz in einem Schaltungssimulator wie z.B. PSPICE geeignet. Die Verifikation der Simulationsergebnisse zwischen ANSYS und PSPICE zeigen eine gute {\"U}bereinstimmung. Der Vergleich zwischen Experiment und der PSPICE Simulation sind akzeptabel. Mit dem vorgestellten Makromodell ist es m{\"o}glich, auf Systemebene schnell verschiedene thermische Randbedingungen und Kabel Geometrien zu modellieren und eine zeitsparende, transient gekoppelte thermo-elektrische Simulation durchzuf{\"u}hren. Da die parametrische Modellierung eine Beschreibung der "realen thermischen" Montagebedingungen (z.B. in einem Auto oder LKW) unterst{\"u}tzt, ist es m{\"o}glich sich einen {\"U}berblick {\"u}ber die thermischen Einfl{\"u}sse und Temperaturen entlang des Stromkabels zu verschaffen und so die Kabelauslegung hinsichtlich Gr{\"o}ße und Gewicht (Kupfer Durchmesser, verwendetes Isoliermaterial) und Einbauort (W{\"a}rmeleitung, Konvektion, Strahlung) zu optimieren.}, language = {de} } @inproceedings{SchachtHausdorfWunderleetal., author = {Schacht, Ralph and Hausdorf, Alexander and Wunderle, Bernhard and Rzepka, Sven and Michel, Bernd}, title = {Efficiency optimization for a frictionless air flow blade fan - design study}, series = {14th IEEE ITHERM Conference, Orlando(Fl), USA, May 30th, 2014}, booktitle = {14th IEEE ITHERM Conference, Orlando(Fl), USA, May 30th, 2014}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4799-5267-0}, pages = {1019 -- 1026}, abstract = {This paper resumes the frictionless fan concept which was introduced at itherm 2012 [1]. This concept was based on a flexible polymer blade, the vibration of which is, as opposite to the piezoelectric driven fan principle, driven by means of a magnetic field. This type of fan can be of interest in regions where otherwise the fluid flow would be stagnant. This paper presents the results of a further in depth design study to reduce power loss and form factor as well as to optimize fan efficiency. Therefore, different blade materials and shapes, different sheet materials for the inductive stimulation as well as the influence of coil shape, value and number were under investigation. As a result, the size could be reduced by half and the efficiency could be doubled. A maximum flow rate of 14 l/min and a static pressure of 3 Pa at 240 mW fan power could be reached.}, language = {en} } @misc{SchachtRzepka, author = {Schacht, Ralph and Rzepka, Sven}, title = {Parametric Transient Thermo - Electrical PSPICE Model F or A Single And Dual Conductor Power Cable}, series = {International Journal of Engineering Research and Development}, volume = {13}, journal = {International Journal of Engineering Research and Development}, number = {2}, issn = {2278-067X}, pages = {44 -- 54}, abstract = {A parametric macro model for a single and dual conductor power cable for transient thermo-electrical coupled simulation in PSPICE will be derived. The article depicts the modelling of a simplified, single- and dual conductor cable and its use during simulation. Its verification against experiment and finite element simulation shows a good agreement. The derived single- and dual conductor PSPICE cable macro model enables a quick modelling at system level. It offers a time saving transient thermo-electrical simulation under various thermal conditions and cable geometries and to optimize e.g. size, weight. The approach support the engineer to overlook the thermal influences and temperatures along the power cable under real 'thermal' assembling conditions in an e.g. car engine room or aircraft.}, language = {en} } @misc{NowakMerboldEgbersetal., author = {Nowak, Torsten and Merbold, Sebastian and Egbers, Christoph and Schacht, Ralph}, title = {Novel Compact-Thermal-Model Approach to Estimate the Heat Spreading Effects of Flip-Chips on PCB regarding Laminar Flow Regimes}, series = {2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, journal = {2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)}, publisher = {IEEE}, isbn = {978-1-7281-2078-2}, issn = {2474-1523}, doi = {10.1109/THERMINIC.2019.8923434}, pages = {6}, abstract = {Today, electronic and thermal engineers want to figure out, which location are the most compliant one, to ensure electronic function of the system and get a reliable thermal design. Numerical simulations can help to understand thermal paths and interactions between electronic parts nearby. However, there are often time consuming, to set-up all material parameters and fluid flow properties. The usage of Compact Thermal Models (CTM) are often used for power application and can provide first solutions to heat transfer via solid substrate, thermal spreading and solid to fluid interactions. Those CTM cannot fully replace a complex fluid mechanical analysis with a Computational Fluid Dynamics (CFD) software environment. Furthermore, CTM can take place in preliminary studies during the early design phase of electronic systems within the implementation of key parameters e.g. thermal conductivity of the substrate, fluid flow velocity, power losses and different dimensions of the system. This paper continuous the experimental and numerical study of to complete an approach for CTM based thermal equivalent resistor networks with consideration of dynamic heat spreading along the substrate and laminar convective fluid interactions on typical Printed Circuit Boards (PCB) with micro-electronic Flip-Chip (FC) assemblies}, language = {en} } @misc{Schacht, author = {Schacht, Ralph}, title = {Designstudie f{\"u}r einen reibungslosen Lamellenl{\"u}fter f{\"u}r das W{\"a}rmemanagement von Elektronik}, series = {Experimentelle Str{\"o}mungsmechanik : 27. Fachtagung 3.-5. September 2019 Erlangen}, journal = {Experimentelle Str{\"o}mungsmechanik : 27. Fachtagung 3.-5. September 2019 Erlangen}, editor = {Delgado, Antonio}, publisher = {Deutsche Gesellschaft f{\"u}r Laser-Anemometrie - German Association for Laser Anemometry GALA e.V.}, address = {Karlsruhe}, isbn = {978-3-9816764-6-4}, pages = {39.1 -- 39.7}, abstract = {In diesem Beitrag werden die Ergebnisse einer Designstudie f{\"u}r einen reibungslosen L{\"u}fter vorgestellt. Im Gegensatz zu einem piezoelektrisch angetriebenen L{\"u}fter basiert der Lamellenl{\"u}fter auf einer flexiblen Lamelle, deren Vibration durch ein Magnetfeld angetrieben wird. Die Lamelle basiert auf einem Polymermaterial. Die Designstudie resultierte in einem Prototyp der Gr{\"o}ße 50 x 14 x 35 mm² inkl. Geh{\"a}use. Der Lamellenl{\"u}fter erreicht dabei einen max. Volumenstrom von V̊ ~14 l/min sowie einen max. statischen Druck von ρstat = 3 Pa.}, language = {de} } @misc{NowakMerboldEgbersetal., author = {Nowak, Torsten and Merbold, Sebastian and Egbers, Christoph and Schacht, Ralph}, title = {Experimentelle Studie mit numerischer Validierung von thermi-schen Kopplungs-Ph{\"a}nomenen mit in Flip-Chip-Technologie aufge-bauten Testchips auf Leiterplatten}, series = {Experimentelle Str{\"o}mungsmechanik : 27. Fachtagung 3.-5. September 2019 Erlangen}, journal = {Experimentelle Str{\"o}mungsmechanik : 27. Fachtagung 3.-5. September 2019 Erlangen}, editor = {Delgado, Antonio}, publisher = {Deutsche Gesellschaft f{\"u}r Laser-Anemometrie - German Association for Laser Anemometry GALA e.V.}, address = {Karlsruhe}, isbn = {978-3-9816764-6-4}, pages = {27.1 -- 27.8}, abstract = {In aktuellen mikro-elektronischen Systemen m{\"u}ssen verschiedene aktive und passive Bauteile auf engstem Raum miteinander auf dem Substrate (bspw. FR4-Leiterplatte) kombiniert werden. Die dabei stetig steigende Leistungsdichte bedarf einer optimierten K{\"u}hlstrategie und der Definition von konduktiven und konvektiven Entw{\"a}rmungspfade, die bereits w{\"a}hrend der Layout-Designphase der Baugruppe ber{\"u}cksichtigt werden sollten. Str{\"o}mungsmechanische Simulationen (CFD) k{\"o}nnen dabei ein erstes Abbild zur Analyse von Kopplungseffekten zwischen den W{\"a}rmequellen und der Umgebung liefern. Diese sind jedoch oft zeitaufwendig und es bedarf zumindest ein gewisses Grundverst{\"a}ndnis, um die Fluid-mechanischen Parameter, das Vernetzen der Geometrien und die gewonnenen Ergebnisse korrekt zu interpretieren. Erste analytische Ans{\"a}tze zur reduzierten Beschreibung von ungeh{\"a}usten Chips auf Leiterplattensubstrat k{\"o}nnen durch thermische Widerstandsnetzwerke abgebildet und durch Aufteilung der W{\"a}rmestr{\"o}me in Richtung Substrat (W{\"a}rmeleitung) und in Richtung des bewegten Fluides (Konvektion) n{\"a}her beschrieben werden.}, language = {de} } @misc{WunderleMayHeilmannetal., author = {Wunderle, Bernhard and May, Daniel and Heilmann, Jens and Arnold, J{\"o}rg and Hirscheider, Josef and Lee, Yi and Bauer, J{\"o}rg and Schacht, Ralph and Abo Ras, Mohamad}, title = {Accelerated Pump Out Testing for Thermal Greases}, series = {20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}, journal = {20th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)}, publisher = {IEEE}, isbn = {978-1-5386-8040-7}, doi = {10.1109/EuroSimE.2019.8724540}, pages = {11}, abstract = {Thermal greases allow a low stress bond at low bond line thicknesses (BLT) at medium thermal conductivities and simple application, all of which make it an alternative to solders, thermal adhesives or pads. It is widely used in power and microprocessor applications, most of which involve large areas to be used for heat transfer. However, for years thermal overload failure of power modules and chips has been a pressing problem due to pump-out of thermal grease as a die or module thermal interface material (TIM): Most thermal greases are Bingham fluids and thus not solids, so they can be squeezed out from in between the gap, driven by thermo-mechanical action of the adjacent layers as e.g. DCB substrate or silicon chip with the heat sink. Today, thermal greases have to be qualified in lengthy stress tests in a product relevant environment which consumes substantial resources as often a system test is required. Therefore, a fast test is necessary which accelerates testing and thus allows a fast screening of commercial greases on one hand, and guidelines for material development on the other. For that purpose this paper addresses this topic in a combined simulative and experimental way, where at the same time a novel test procedure is proposed for accelerated grease pump-out testing (GPOT) in the framework of a completely new approach, combining loading with in-situ failure analytical techniques and decoupling thermal from mechanical loading. This allows for the first time a realistic loading of greases during accelerated testing with testing times below one hour. The method is demonstrated on various commercial and custom greases, varying their composition and structure, and benchmarked against industry standard thermal cycling tests. Further, two fundamental failure mechanisms have been identified being at work simultaneously, notably fluid transport (which constitutes actually a pump-in phenomenon) and air entrapment. We were able to identify key properties of the materials and loading variables, on which their intensity depends.}, language = {en} } @misc{WargulskiNowakThieleetal., author = {Wargulski, Dan and Nowak, Torsten and Thiele, Magnus and Dobbelstein, Henrick and Schacht, Ralph and Abo Ras, Mohamad}, title = {Quality management of laser cladding processes for additive manufacturing by new methods of visualization and evaluation of thermographic data}, series = {Quantitative InfraRed Thermography Journal}, volume = {17}, journal = {Quantitative InfraRed Thermography Journal}, number = {1}, issn = {2116-7176}, doi = {10.1080/17686733.2019.1592392}, pages = {1 -- 12}, abstract = {Additive manufacturing by laser cladding is a promising tool for rapid prototyping, buildup of bionic structures and replacement part production. To ensure a constant quality of manufactured components and to shorten the development process between CAD model and suitable produced components a quality management system is inevitable. Therefore, a system has been developed to evaluate the cladding process by means of thermographic measurements. Melt pool temperature measurements by a thermal imaging camera has been processed to 2- and 3-dimensional temperature maps of the manufactured component, like a tomographic image, to easily reveal weak spots in the process and the component itself. The quality management system was tested and evaluated on several laser-cladding processes with various failures.}, language = {en} } @misc{SchachtRzepka, author = {Schacht, Ralph and Rzepka, Sven}, title = {Transient Electro-Thermal Coupled System Simulation - Modeling Approach and Experimental Validation}, series = {17th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)}, journal = {17th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)}, isbn = {978-1-5386-1272-9}, doi = {10.1109/ITHERM.2018.8419490}, pages = {8}, abstract = {This contribution describes an approach for modeling a coupled electro-thermal design problem for the transient system simulation based on the analog circuit simulator SPICE - means: the time-varying electrical functional behavior of several neighboring components influence the time-varying thermal behavior of the setup and interconnection environment, which in turn affects the time-varying electrical behavior of these components. Due to the SPICE model description this is currently not possible. For this purpose, both electrical and thermal modeling methods as well as the coupling of these models are presented. The electrical model is based on the fundamental equations of semiconductor physics. With the help of the respective physical parameters, the electrical model can easily be extended to an existing library component or that of a manufacturer component SPICE description. The thermal model is based on a modified Foster model extracted from transient FEM simulation results, using the thermal step response. Thus, during the coupled transient simulation, both, the electrical behavior of the component, due to its self-heating, and the coupling heating of adjacent components, can be taken into account. The method is shown and experimentally verified by the example of two interacting MOSFETs with D2PAK packages, using a specially developed test board}, language = {en} } @misc{NowakMerboldEgbersetal., author = {Nowak, Torsten and Merbold, Sebastian and Egbers, Christoph and Schacht, Ralph}, title = {Numerical Study with Experimental Validation of Thermal Coupling Phenomena with Flip-Chip Assembled Test Dies on PCB}, series = {24th INTERNATIONAL WORKSHOP on Thermal Investigations of ICs and Systems, 2018}, journal = {24th INTERNATIONAL WORKSHOP on Thermal Investigations of ICs and Systems, 2018}, publisher = {IEEE}, isbn = {978-1-5386-6759-0}, issn = {2474-1523}, doi = {10.1109/THERMINIC.2018.8593313}, pages = {5}, abstract = {Numerical Study with Experimental Validation of Thermal Coupling Phenomena with Flip-Chip Assembled Test Dies on PCB.}, language = {en} }