Diploma thesis solves how to create system for measurement of little liquid flows. The basic types of liquid flowmeter, which are possible used for measurement of little liquid flows, are described in the introduction part of thesis. The limit for little flow is often determined as flow 100 mg.min-1 and low. Second part of this thesis describes the ways of capillary production and practical experiments with them. Thesis is focused to thick film technology and LTCC technology. Next part of this work is solution of simple measuring unit for measurement of little flows less than 100 mg.min 1, which is controlled by microprocessor ATmega16. The measuring unit can be worked separately or can be connected to PC. The next possibility of flowmeter optimisation is summarized in end of thesis.

This thesis deals with the mixing of liquids issues. The simulation of structure for mixing of liquids and evaluation of parametres which have most significant influence on mixing of liquids was made with help of COMSOL programm. In the next section of thesis the quality of electrodes used for cyclic voltammetry made on LTCC by thick layer technology was determined. In the end of this thesis the 3D structure for mixing of liquids was made. The quality of mixing was controlled by cyclic voltammetry.

The present work deals with the design and manufacturing of 3D structures in LTCC (Low Temperatue Cofired Ceramics) technology. To use this technology LTCC workplaces have been designed and technological processes for high quality reproducible production were suggested. Technological possibilities of low temperature co-fired ceramics were demonstrated in the design and manufacturing of pressure sensors, electrode systems for ozone generators, planar circuit elements (coils and transformers) and in the design a special package for middle-power terahertz modulator. Design of selected parts of respective devices was proved by simulations in COMSOL Multiphysics. The work provides new insights into the structure of power integrated circuits sleeves and structure of electrode systems for different types of electrical discharges. Results of this work can contribute significantly in the application of planar circuit elements, in the development of different types of sensors, in the design of atypical types of packaging or in the design of electrode systems for capacitive coupled electrical discharges.

Les systèmes embarqués dans les aéronefs comme dans les véhicules spatiaux doivent impérativement se conformer aux impératifs de masse et de volume mais aussi de coût. Les modules actifs pour antenne à balayage électronique constituent, dans ce cadre, un enjeu stratégique majeur en termes de masse, de volume et de fiabilité. Dans une antenne à balayage électronique actuelle, on peut trouver jusqu’à 1000 modules, chacun étant équipé d’un circulateur-isolateur afin de garantir ses performances. La technologie des circulateurs et des isolateurs à ferrite reste la plus performante en termes d’isolation et de pertes d’insertion. Elle est de plus totalement passive et ne demande aucune énergie extérieure pour son fonctionnement. Elle reste néanmoins coûteuse car la fabrication industrielle de ces dispositifs consiste à assembler mécaniquement de nombreuses pièces usinées précisément : céramiques magnétiques et diélectriques, aimants, conducteurs en cuivre et pièces en métal magnétique doux. De plus, le niveau d’intégration recherché nécessite de réduire les dimensions sans augmenter les pertes pour des niveaux de puissance qui peuvent être importants. S’inspirant des composants céramiques multicouches (condensateurs et inductances) ainsi que de la technologie LTCC (Low Temperature Cofired Ceramics), une nouvelle voie de fabrication de ces composants, en rupture avec les technologies d’assemblage traditionnelles, est abordée dans ces travaux de thèse. L’idée consiste à réaliser par cofrittage le cœur du composant qui est le plus délicat à ajuster et qui détermine le volume final. Les ferrites qui constituent actuellement le cœur des circulateurs sont principalement des grenats ferrimagnétiques fabriqués par des techniques céramiques classiques et frittés à haute température (> 1400°C). Pour les rendre compatibles de la technologie LTCC, il est nécessaire de diminuer leur température de frittage. Les températures visées doivent être inférieures à 1000°C pour pouvoir cofritter avec des parties métalliques en or et si possible être proches de 900°C pour espérer cofritter avec de l’argent. Dans ce contexte, l’objectif de ce travail de thèse était de mettre au point des grenats ferrimagnétiques pour des applications en hyperfréquences présentant des températures de frittage proche de 900°C. Ces ferrites ont alors été utilisés pour la réalisation de circulateurs hyperfréquences, composants indispensables dans les systèmes de Radars et de télécommunications. De plus, des études d’optimisation des propriétés magnétiques et diélectriques de ces ferrites ont aussi été réalisées pour adapter le ferrite aux conditions de fonctionnement (gamme de fréquence et niveau de puissance). / Embedded systems in aircraft must comply with the requirements of mass, volume and cost. The active modules of electronic scanning antenna are, in this context, a strategic challenge in terms of mass, volume and reliability. Today, there are up to 1000 modules per antenna, each one containing a circulator-isolator in order to guarantee its performances. The technology of ferrite circulators and isolators remains the most efficient in terms of isolation and insertion losses. It is also fully passive as no external energy is required to work. However this technology is expensive due to complex mechanical assembling of the different materials: magnetic and dielectric ceramics, magnets, conductors made of copper and soft metallic material. The integration of such devices also requires the reduction of dimensions without increasing losses for power levels that can be high. Based on by multilayer ceramic components (capacitors and inductors) as well as Low Temperature Cofired Ceramics (LTCC) technology, a new way of manufacturing these components, is investigated in this PhD work.. The idea is to be able to cofire the heart of the component which is the most difficult to adjust and also determines the final volume. The ferrites which currently constitute the core of the circulators are ferrimagnetic garnets synthetized by using a conventional ceramic process and sintered at high temperature (> 1400°C). To make them compatible with LTCC technology, it is essential to reduce their sintering temperature. The targeted temperatures must be less than 1000°C in order to cofire with gold metal parts and, if possible, close to 900°C for circulators with silver. In this context, the objective of this PhD work was to develop a ferrimagnetic garnet for microwave applications with sintering temperatures close to 900°C. This ferrite was then used for the preparation of microwave circulators which are essential components in radar and telecommunications systems. In addition, studies of optimization of the magnetic and dielectric properties have also been carried out to meet the operating requirements (frequency band and power level).

Glaskeramische Komposite, deren Herstellung von Glas- und kristallinen Pulvern ausgeht, bieten vielfältige Möglichkeiten, Werkstoffeigenschaften, wie z.B. Sinterverhalten, thermische Dehnung, mechanische Eigenschaften, chemische Beständigkeit, dielektrische Eigenschaften und Oberflächenqualität für spezielle Anwendungszwecke gezielt einzustellen. Glaskeramische Kompositpulver können zu Folien verarbeitet werden, aus denen mittels der LTCC (Low Temperature Co-fired Ceramics)- Technologie keramische Multilayer hergestellt werden, die insbesondere für das Electronic Packaging von Mikrosystemen eingesetzt werden. Problematisch ist die beim freien Sintern der LTCC-Multilayer auftretende laterale Schwindung, die von relativ hohen Schwindungstoleranzen begleitet ist. Zur Vermeidung der lateralen Schwindung werden Zero Shrinkage-Techniken eingesetzt. Eine neue Möglichkeit Zero Shrinkage beim Sintern von LTCC-Multilayern zu erreichen, besteht in der Anwendung eines self-constrained Laminates. Hierbei wird ein Multilayer eingesetzt, der aus zwei unterschiedlichen Folienarten für innere und äußere Lagen mit deutlich verschiedenen Sintertemperaturen (ΔT > 50 K) aufgebaut wird. Die Entwicklung von LTCC-Werkstoffen, die als innere Lagen eines self-constrained Laminates zur Verringerung der lateralen Sinterschwindung auf nahezu Null eingesetzt werden können, war Gegenstand der vorliegenden Arbeit. Es wurden hierfür LTCC-Werkstoffe aus dem Stoffsystem CaO-La2O3-Al2O3-B2O3 untersucht, die bei Temperaturen unterhalb 800 °C dicht gesintert werden können. Ausgehend von der Entwicklung geeigneter Gläser auf der Basis von Calciumlanthanborat- sowie Calciumlanthanalumoboratgläsern wurden glaskeramische Komposite unter Zusatz von Korundpulver hergestellt. Die Komposite kristallisieren während des Brennprozesses nahezu vollständig. Aus der Glasphase kristallisiert Lanthanborat aus und aufgrund der festkörperchemischen Reaktion der calciumboratreichen Restglasphase mit dem Korund bilden sich vor allem Calciumalumoborat bzw. Calciumalumoboratoxid. Die Anteile an neuen Phasen bestimmen die thermischen und dielektrischen Eigenschaften der Werkstoffe. Die wichtigsten der sich bildenden kristallinen Phasen der Komposite, Lanthanborat und Calciumalumoboratoxid wurden separat hergestellt und charakterisiert. Das Sinter- und Kristallisationsverhalten sowie die thermischen und dielektrischen Eigenschaften der glaskeramischen Komposite wurden in Abhängigkeit von den entwickelten Gläsern, dem Volumenverhältnis von Glas- und kristalliner Komponente im Kompositpulver und der Brenntemperatur untersucht. Die entwickelten LTCC-Werkstoffe wurden bzgl. ihrer thermischen Eigenschaften an einen zuvor ausgewählten LTCC-Werkstoff für die äußeren Lagen eines self-constrained Laminates angepasst. Erzielt wurden die Eigenschaftswerte: TEC: ca. 5 x 10-6/K, er: ca. 7 und tan δ: ≤ 1 x 10-3. Zur Überprüfung der Anwendbarkeit wurde der entwickelte LTCC-Werkstoff als innere Lagen in einem LTCC-Multilayer verarbeitet. Dadurch konnte die laterale Schwindung des Multilayers beim Sintern auf < 0,4 % verringert werden.

The non-isolated POL converters are widely used in computers, telecommunication systems, portable electronics, and many other applications. These converters are usually constructed using discrete components, and operated at a lower frequency around 200 ~ 600 kHz to achieve a decent efficiency at the middle of 80's%. The passive components, such as inductors and capacitors, are bulky, and they occupy a considerable foot-print. As the power demands increase for POL converters and the limited real estate of the mother board, the POL converters must be made significantly smaller than what they have demonstrated to date. To achieve these goals, two things have to happen simultaneously. The first is a significant increase in the switching frequency to reduce the size and weight of the inductors and capacitors. The second is to integrate passive components, especially magnetics, with active components to realize the needed power density. Today, this concept has been demonstrated at a level less than 5A and a power density around 300-700W/in3 by using silicon-based power semiconductors. This might address the need of small hand-held equipment such as PDAs and smart phones. However, it is far from meeting the needs for applications, such as netbook, notebook, desk-top and server applications where tens and hundreds of amperes are needed. After 30 years of silicon MOSFET development, the silicon has approached its theoretical limits. The recently emerged GaN transistors as a possible candidate to replace silicon devices in various power conversion applications. GaN devices are high electron mobility transistors (HEMT) and have higher band-gap, higher electron mobility, and higher electron velocity than silicon devices, and offer the potential benefits for high frequency power conversions. By implementing the GaN device, it is possible to build the POL converter that can achieve high frequency, high power density, and high efficiency at the same time. GaN technology is in its early stage; however, its significant gains are projected in the future. The first generation GaN devices can outperform the state-of-the-art silicon devices with superior FOM and packaging. The objective of this work is to explore the design of high frequency, high power density 12 V input POL modules with GaN devices and the 3D integration technique. This work discusses the fundamental differences between the enhancement mode and depletion mode GaN transistors, the effect of parasitics on the performance of the high frequency GaN POL, the 3D technique to integrate the active layer with LTCC magnetic substrate, and the thermal design of a high density module using advanced substrates with improved thermal conductivity. The hardware demonstrators are two 12 V to 1.2 V highly integrated 3D POL modules, the single phase 10 A module and two phase 20 A module, all built with depletion mode GaN transistors and low profile LTCC inductors. / Master of Science

No description available.

Point-of-load (POL) converters have been used extensively in IT products. Today, almost every microprocessor is powered by a multi-phase POL converter with high output current, which is also known as voltage regulator (VR). In the state-of-the-art VRs, the circuits are mostly constructed with discrete components and situated on the motherboard, where it can occupy more than 1/3 of the footprint of the motherboard. A compact POL is desirable to save precious space on motherboards to be used for some other critical functionalities. Recently, industry has released many modularized POL converters, in which the bulky inductor is integrated with the active components to increase the power density. This concept has been demonstrated at current levels less than 5A and power density around 600-1000W/in³. This might address the needs of small hand-held equipment such as smart phones, but it is far from meeting the needs for the applications such as laptops, desktops and servers, where tens and hundreds of amperes are needed. A 3D integrated POL module with an output current of tens of ampere has been successfully demonstrated at the Center for Power Electronic Systems (CPES), Virginia Tech. In this structure, the inductor is elaborated with low temperature co-fire ceramic (LTCC) ferrite, as a substrate where the active components are placed. The lateral flux inductor is proposed to achieve both a low profile and high power density. Generally, the size of the inductor can be continuously shrunk by raising the switching frequency. The emerging gallium-nitride (GaN) power devices enable the creation and use of a multi-MHz, high efficiency POL converter. This dissertation firstly explores the LTCC inductor substrate design in the multi-MHz range for a high-current POL module with GaN devices. The impacts of different frequencies and different LTCC ferrite materials on the inductor are also discussed. Thanks to the DC flux cancellation effect, the inverse coupled inductor further improves the power density of a 20A, 5MHz two-phase POL module to more than 1kW/in³. An FEA simulation model is developed to study the core loss of the lateral flux coupled inductor, which shows the inverse coupling is also beneficial for core loss reduction. The ceramic-based 3D integrated POL module, however, is not widely adopted in industrial products because of the relatively high cost of the LTCC ferrite material and complicated manufacturing process. To solve that problem, a printed circuit board (PCB) inductor substrate with embedded alloy flake composite core is proposed. The layerwise magnetic core is laminated into a multi-layer PCB, and the winding of the inductor then is formed by the copper layers and conventional PCB vias. As a demonstration of system integration, a 20A, 1.5MHz integrated POL module is designed and fabricated based on a 4-layer PCB with embedded flake core, which realizes more than 85% efficiency and 600W/in³ power density. The application of standardized PCB processes reduces the cost for manufacturing the integrated modules due to the easy automation and the low temperature manufacturing process. Combining the PCB-embedded coupled inductor substrate and advanced control strategy, the two-phase 40A POL modules are elaborated as a complete integrated laptop VR solution. The coupled inductor structure is slightly modified to improve its transient performance. The nonlinearity of the inductance is controlled by adding either air slots or low permeability magnetic slots into the leakage flux path of the coupled inductor. Then the leakage flux, which determines the transient response of the coupled inductor, can be well controlled. If we directly replace the discrete VR solution with the proposed integrated modules, more than 50% of the footprint on the motherboard can be saved. Although the benefits of the lateral flux inductor have been validated in terms of its high power density and low profile, the planar core is excited under very non-uniform flux. Some parts of the core are even pushed into the saturation region, which totally goes against the conventional sense of magnetic design. The final part of this dissertation focuses on evaluating the performance of the planar core with variable flux. The counterbalance between DC flux and AC flux is revealed, with which the AC flux and the core loss density are automatically limited in the saturated core. The saturation is essentially no longer detrimental in this special structure. Compared with the conventional uniform flux design, the variable flux structure extends the operating point into the saturation region, which gives better utilization of the core. In addition, the planar core with variable flux also provides better thermal management and more core loss reduction under light load. As conclusions, this research first challenges the conventional magnetic design rules, which always assumes uniform flux. The unique characteristics and benefits of the variable flux core are proved. As an example of taking advantages of the lateral flux inductor, the PCB integrated POL modules are proposed and demonstrated as a high-density VR solution. The integrated modules are cost-effective and ready to be commercialized, which could enable the next technological innovation for the whole computing and telecom industry. / Ph. D.

Ces dernières années, les besoins en électronique de puissance s’orientent vers la miniaturisation globale des cartes électroniques, parallèlement à une augmentation des puissances de travail. C’est dans ce contexte que s’inscrivent les travaux de cette thèse, principalement axée sur l’élaboration, l’amélioration des performances et l’intégration de composants passifs (inductances, transformateurs…) en électronique de puissance.Les matériaux choisis pour remplir les fonctions magnétiques de ces composants dans leurs conditions de travail sont les ferrites NixZn1-xFe2O4 (0<x<1). Du cuivre est ajouté pour diminuer la température de frittage, de plus de 1200 °C à moins de 950°C, permettant le cofrittage avec un métal conducteur, et du cobalt pour diminuer les pertes totales en puissance du ferrite formé. La formulation finale devient alors (NixZnyCuz)1-εCoεFe2-δO4 (x+y+z=1). Enfin, de l’oxyde de bismuth Bi2O3 est ajouté comme fondant pour abaisser encore la température de frittage et éviter les problèmes de diffusion.Après une étude bibliographique, les travaux se sont orientés selon différents axes. Il s’agissait tout d’abord d’optimiser la formulation du ferrite pour élaborer des échantillons aux propriétés électromagnétiques et physicochimiques ciblées. Cet axe de travail regroupe de nombreuses études sur la formulation des ferrites Ni-Zn-Cu-Co, parmi lesquelles les principales sont l’étude de l’influence de la stœchiométrie en fer, du rapport Ni/Zn dans la formulation et du procédé d’ajout de cobalt selon son taux. Ces travaux ont permis de mettre en évidence qu’un léger défaut de fer maîtrisé (~Fe1,98) pouvait améliorer les propriétés et les performances de ces ferrites. L’étude de l’influence du rapport Ni/Zn a permis la réalisation de ferrites à perméabilités très faibles, de 40 à 135, et aux bonnes performances en puissance. Les résultats de cette étude ont été publiés dans le Journal of the Japan Society of Powder and Metallurgy. Tout au long de la thèse, l’élaboration d’échantillons céramiques, base incontournable de chaque étude, a été réalisé au laboratoire, comme la plupart des tests et caractérisations. Ces derniers peuvent être microstructuraux et physicochimiques (DRX, MEB, BET, ATD/ATG…), ou électromagnétiques (mesures d’aimantation, de perméabilité, de pertes en puissances, etc…).La finalité de ces travaux étant l’intégration de puissance, cette dernière représente le second axe majeur, et regroupe également de nombreuses études, parmi lesquelles les principales sont les études des influences du bobinage sur les pertes d’un composant de type inductance et de l’entrefer (espacement amagnétique au sein du circuit magnétique), classiquement utilisé pour diminuer la perméabilité apparente, non sans conséquence sur les performances en puissance. Une campagne de mesures de pertes totales a également été réalisée dans l’objectif de dégager des lois comportementales sur la variation de ces pertes en puissance et en fréquence.Tous ces travaux et leurs résultats sur le matériau ferrite, son utilisation en électronique de puissance, et une bonne maîtrise du procédé d’élaboration (notamment multicouche), ont permis la réalisation de microcomposants passifs intégrables, aux propriétés ciblées et aux très bonnes performances (pertes diminuées d’un facteur 6 à 10 par rapport au commerce). / In recent years, power electronics needs are moving towards the global miniaturization of electronic boards, and an increase of the working powers. The works performed during this thesis, mostly oriented on the elaboration, the performances improvement and the integration of passive components (inductors, transformers…) in power electronics, are inscribed in this context.The materials chosen to perform the magnetic functions of those components in their work conditions are the NixZn1-xFe2O4 (0<x<1) ferrites. Copper is added to reduce the firing temperature, from more than 1200 °C to less than 950 °C, allowing cofiring with a conducting metal, and cobalt is added to reduce the power core losses of the sintered ferrite. The final formulation then becomes (NixZnyCuz)1-εCoεFe2-δO4 (x+y+z=1). Finally, bismuth oxide Bi2O3 is added as a sintering aid to lower even more the sintering temperature and avoid diffusion problems.After a bibliographic study, the works were oriented along different axes. Firstly, the ferrite formulation was optimized to elaborate samples with targeted electromagnetic and physicochemical properties. This working axis gathers numerous studies on the Ni-Zn-Cu-Co ferrites formulation, among which the main ones are the study of the influence of iron stoichiometry, the Ni-Zn ratio in the formulation and the cobalt adding process and level. These studies have shown that a light and controlled iron deficiency (~Fe1,98) could improve the properties and the performances of these ferrites. The study of the influence of the Ni/Zn ratio allowed the production of very low permeability ferrites, from 40 to 135, with good power performances. Its results were published in the Journal of the Japan Society of Powder and Metallurgy. Throughout this thesis, the elaboration of ceramic samples, the essential basis of every study, was undertaken at the laboratory, as most of the tests and characterizations. These can be microstructural and physicochemical (XRD, SEM, BET, TDA/TGA…), or electromagnetic (magnetization and permeability measurements, power losses…).The final purpose of this work is power integration, and it represents the second main axis. It also gathers many studies, among which the main ones are the study of the influence of the winding on the losses of an inductor-type component and the influence of the air gap, commonly used to reduce the apparent permeability, not without consequences on the power performances. A total losses measurement campaign has also been undertaken in order to bring out behavioral laws on core losses variation according to induction and frequency.All this work and the results on the ferrite material, his power electronic application, and a good control of the elaboration process (multilayer especially), allowed the production of passive micro-components for integration, with targeted properties and very high performances (core losses reduced by 6 to 10 relative to commercial materials).

La demande toujours croissante de connectivité et de débit de données requiert une rupture dans la conception des futurs réseaux de communication et systèmes radio. Plusieurs applications émergentes en bande millimétrique, notamment les réseaux mobiles de cinquième génération (5G) et les communications satellites, exigent des antennes large bande qui assurent une grande couverture angulaire, tout en étant à la fois compactes, facilement intégrables et à bas coût.Cette thèse propose des systèmes antennaires multifaisceaux large bande et à très grande couverture angulaire, appelés «Continuous Transverse Stub Antenna» (CTS), pour réaliser un bon compromis de l’ensemble de ces objectifs. L’architecture de l’antenne comprend un réseau de fentes longues excitées par un réseau d’alimentation en chandelier, basé sur des guides d’onde à plans parallèles. Cette structure est excitée par un formateur de faisceaux quasi-optique co-intégré. La première partie du manuscrit présent des nouveaux modèles numériques qui facilitent la conception de chaque sous-système de l’antenne et permettent l’analyse des performances globales, soit en termes d’adaptation, soit en termes de diagrammes de rayonnement. Ces outils sont exploités pour la conception d’antenne et pour étudier les limites en balayage. La thèse se poursuit en présentant de nouvelles solutions technologiques et de nouveaux design pour intégrer les antennes CTS dans des modules multicouches planaires et à faible profil. La conception et la caractérisation de deux antennes intégrées en technologie LTCC pour des points d’accès 5G à 60 GHz sont discutées. L’une des deux est à faisceau fixe, l’autre est à balayage électronique, avec une couverture de ±40°, de faibles lobes secondaires et un niveau élevé de recoupement des faisceaux. Enfin, nous proposons l’association de radomes polarisants planaires à faible profil aux antennes CTS, pour réaliser des systèmes rayonnants en polarisation circulaire. Une méthodologie systématique pour la conception de polarisateurs à très large bande est présentée, ainsi qu’un design couvrant entièrement la bande Ka pour des applications satellites. / The ever-growing demand for fast and seamless connectivity shows the need of new wireless standards and technologies. Novel broadband, wide-angle scanning antennas achieving an optimal trade-off among size, gain, efficiency and costs are crucial to the development of emerging applications at millimeter waves, such as fifth-generation (5G) mobile networks and satellite communications. In this thesis, multibeam parallel-fed continuous transverse stub (CTS) array antennas are proposed as possible candidates for future mm-wave communications and are developed to tackle these requirements. The antenna architecture comprises an array of long slots, a corporate feed network based on parallel plate waveguides (PPWs) and an integrated quasi-optical beamformer. First, novel numerical models for the analysis of each subsystem and of the overall antenna, are presented, which enable an efficient and modular design of CTS antennas. These tools are exploited to derive design guidelines and assess the scanning performance. Then, novel design and technological solutions for the integration of CTS antennas in flat, low-profile multilayer modules are discussed. The design and characterization of two prototypes in LTCC technology, for 60-GHz mobile access points are presented: a fixed beam array and a switched-beam antenna with a field of view of ±40°, low SLLs and high beam overlap. Finally, planar linear-to-circular polarization converters are proposed to realize circularly polarized CTS antenna systems. A procedure to achieve an ultra-wideband, low-loss polarization conversion is outlined and a design for Ka-band satellite application is presented.