Figure 3
2: Theoretical characteristic impedance of a microstrip line as a function of the ratio strip width to substrate thickness (w ms /h ms ). The ESL41110 material presents a ratio of 2 for 50 Ω microstrip line
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This thesis concerns the introduction and development in our laboratory of a multilayer ceramic technology, called LTCC, for RF and microwave packaging. LTCC stands for Low Temperature Co-fired Ceramics. As can be understood from its name, the low temperature means that the LTCC circuit is fired below 1000 °C that allows the use of high conductivit...
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This paper presents design, fabrication and characterization of novel inter-layer microheaters based on low temperature co-fired ceramics (LTCC) technology. LTCC microheater structures (S1 to S3) with three different heater configurations has been presented. Microheater structure S1 has a heater pattern generated only on the top LTCC layer while S2...
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... Les feuilles sont déposées les unes sur les autres par lamination. Une fois les couches empilées, l'ensemble est recuit à haute température, entre 850 et 1000°C [57] [69], afin de jointer les couches céramiques entre elles et de former un bloc compact [69]. ...
La complexité des systèmes RF intégrés pour les applications sans fil grand public s’accroit, et exige de revisiter l’intégration des circuits passifs RF et microondes. De nouvelles solutions offrant plus de compacité et de performance doivent être recherchées, avec un coût de fabrication qui doit rester faible. Parmi celles-ci, une filière technologique 3D de type « Integrated Passive Devices » (IPD) est développée au LAAS CNRS et par la société 3DiS Technologies depuis plusieurs années. Après avoir démontré les capacités de la technologie pour l’intégration de solénoïdes extrêmement compacts et performants, le travail présenté dans ce manuscrit ajoute l’intégration des condensateurs pour faire évoluer la technologie vers la fabrication de fonctions passives RF complexes.Le manuscrit s’articule en trois chapitres. Une première partie dresse une revue des procédés technologiques existants pour la fabrication de systèmes RF et met en évidence l’importance de disposer de composants passifs compacts et performants pour pouvoir intégrer les circuits MMIC. Dans ce contexte, nous présentons les avantages apportés par une solution d’intégration 3D bas coût telle que celle proposée. Dans une deuxième partie, nous présentons le développement de condensateurs Métal Isolant Métal (MIM). Les caractérisations montrent que les condensateurs présentent des performances équivalentes à celles recensées dans la littérature avec de très bons coefficients de qualités. Nous appliquons ensuite la technologie 3D complète à la réalisation de deux transformateurs adaptés en impédance 50 ohms en utilisant des condensateurs. Le procédé technologique de fabrication des deux circuits est décrit. Dans la bande d’adaptation, les circuits fabriqués et caractérisés affichent des pertes en transmission équivalentes aux pertes théoriques minimales estimées à partir du gain disponible maximum des transformateurs. Ces résultats confirment les bonnes performances des condensateurs MIM développés qui introduisent des pertes minimes pour les circuits fabriqués. Aucun problème de fabrication n’est relevé pour les transformateurs adaptés, ce qui permet de valider le procédé technologique complet pour l’intégration de condensateurs et de solénoïdes.Sur la base de ces résultats, le dernier chapitre est consacré au développement d’une matrice de Butler 4×4 destinée à piloter un faisceau de quatre éléments rayonnants en visant la 5G comme contexte applicatif. Des pertes en transmissions inférieures à 3,5 dB et un écart sur les déphasages en sorties de 16° sont relevés pour une large bande passante de 24 GHz à 29 GHz. Ces résultats de mesure sont à l’état de l’art et surpassent les solutions existantes, en particulier au niveau de la surface occupée de seulement 0,84 mm2. Ces résultats démontrent le potentiel de la technologie 3D à réaliser un compromis innovant entre densité d’intégration et performances.
... Capacitors made up of typical LTCC bands with low relative permittivity have a small capacity density but can withstand high voltage. The application of LTCC powder-based bands with high permittivity, for example, BaTiO3 or CaCu3Ti4O12, can increase the capacity density in ceramic modules [12,[15][16][17]. ...
In this paper, we present the dimensioning as well as the thermal and electrostatic modelling of a multilayer capacitor low-temperature co-fired ceramic (LTCC) to insert it in a Buck converter. We also present the different stages of the realization of the LTCC capacitor. Our aims are volume and weight reduction, good frequency behaviour, low values of the series inductance and series resistance, and small ripples of the output voltage. The results obtained after the realization are satisfactory and encouraging, with a 92% reduction in volume and 99% in the surface area. To validate the correct operation of the capacitor, we used the PSIM simulation software to compare the voltage and current waveforms of the outputs of the Buck converter with a perfect capacitor and others with LTCC capacitor. COMSOL multiphysics simulation software allowed us to determine the operating temperature of the LTCC capacitor and to validate its electrostatic behaviour (distribution of electrical potential, of electrical field and electrical current density). The multilayer capacitor is manufactured in the LAPLACE laboratory at Paul Sabatier University.
... Besides, although the thermal properties of LTCC depend on its chemical composition [13], its thermal conductivity is relatively low compared to that of other typical substrates (e.g. alumina) [14]. The addition of an AlN thin film overlayer is a solution to this issue, as this nitride is a much better material to dissipate heat, an important issue for active devices [15]. ...
Three GaN layers grown on polished AlN buffer films previously sputtered on Low-Temperature Co-fired Ceramic substrates have been studied by X-Ray Diffraction, Atomic Force Microscopy and Electron Microscopy related techniques. This allowed to assess the quality of the whole fabricated III-N/LTCC heterostructures considering factors such as superficial roughness, crystallinity, structural features (e.g.: lattice defects) and chemical homogeneity. All the AlN and GaN films were chemically uniform. However, for different regions and growth conditions, properties like the GaN average grain size or roughness varied significantly, and polycrystalline or partially single-crystalline GaN areas, with an elevated density of lattice defects, were identified. The particular surface structure of the LTCC substrate was regarded as key for the formation of these features, as it notably affected the AlN structure. Additional characteristics, like a different degree of c-axis orientation of the GaN grains or formation of small cubic GaN domains depending on the fabrication conditions, were also detected.
Real-time structural health monitoring (SHM) of engineering components exposed to high temperature and pressure is an utmost need. The hostile operating conditions such as elevated temperatures, contraction/expansion, vibrations etc. may lead to catastrophic failure due to creep, thermo-mechanical fatigue or environmental attack (oxidation and hot corrosion). Non-availability of sensors susceptible at high temperature (HT) is a reason to handicap assessment and monitoring of such degradation during operation. Sensors using micro-fabricated sensing element are the promising, non-contact technology that have significant potential in structural health monitoring of critical engineering components operated at elevated temperatures. The present paper addresses this issue by developing application specific high-temperature sensors for real time condition monitoring of the components operated at high temperature. The goal is to provide superior performance for in- situ material condition monitoring (material degradation, flaw detection, stress relaxation, and/or creep monitoring) and through-wall temperature measurement. The sensor consists of a micro-fabricated primary (drive) winding and a secondary winding adjacent to the primary for sensing the response to a material under test. Multiple coils are cascaded / stacked together to increase the SNR and sensitivity of the sensor. The effectiveness of the proposed technique is first demonstrated on synthetic dataset from an eddy current simulation model. Further work is being underway for addressing the issues at elevated temperature.
With Industry 4.0 becoming increasingly pervasive, the importance and usage of sensors has increased several folds. Industry 4.0 refers to a new phase in the industrial revolution that mainly focuses on interconnectivity, automation, machine learning, and real-time data. Real-time structural health monitoring (SHM) of components in the industrial process is one of the crucial and important component of Industry 4.0. SHM of components exposed to high-temperature (
$\sim 650^{\circ }\text{C}$
) is becoming increasingly important nowadays. However, harsh and high temperature environments impose a great challenge towards their implementation. This review is an attempt to demonstrate the development, application, limitations and recent advancement of the existing sensors used for SHM. Some sensors such as eddy current (EC) sensors and fiber Bragg grating (FBG) sensors have been discussed in detail. A phenomenological study of the electromagnetic sensor for the SHM of engineering components that are exposed to high temperature has been addressed. State-of-the-art fabrication methodologies such as low temperature co-fired ceramic (LTCC) technology for such type of sensors for high temperature SHM applications have been elucidated. Future challenges and opportunities for SHM applications of high temperature sensors have been highlighted.
Cette thèse a pour objectif de réaliser des modules d''émission-réception (front-end TRX) faible coût, en band D (110-170 GHz), utilisant des puces intégrées MMIC reportées sur un substrat LTCC. Les applications visées à ces fréquences sont diverses : l'imagerie (sécurité) par le déploiement de scanners haute résolution, les radars automobiles d'aide à la conduite, la radiométrie ou encore le "back-haul" du réseau de téléphonie 5G. Aux fréquences très élevées, les boîtiers sont généralement réalisés à partir de structures métalliques, ce qui les rend coûteux, volumineux et relativement longs à fabriquer. Des solutions de mise en boîtier basées sur la technologie LTCC ont été proposées et développées au cours de la thèse avec l'objectif de maintenir les performances intrinsèques des puces avant report. Pour intégrer les puces MMIC sur le support LTCC, différents aspects ont été étudiés et validés expérimentalement, avec les difficultés en mesure inhérentes à ces fréquences de fonctionnement très élevées. Il s'agit en particulier des techniques d'interconnexion pour relier les plots d'accès RF de la puce aux plots sur substrat et du contrôle technique pour maîtriser l'échauffement de certaines puces, comme l'amplificateur de puissance, qui peut provoquer un dysfonctionnement voire une défaillance du module. La mise en place des réseaux d'alimentation continue des puces actives est également un point crucial dans la conception du boîtier puisqu'ils ne doivent pas interférer avec les accès RF.
This thesis is on the subject of millimeter-wave frequencies (from 30 to 300 GHz) packaging of integrated circuits. Potential applications are radar imaging and security applications as well as TRX (transmission and reception) modules for 5G base stations to give some examples. For these applications, integrated circuits are now available from the manufacturers; however the packaging development for their integration is not advancing with the same pace. Standard packaging solutions does not exist over 50 GHz, which is detrimental to technological development. Thus, this thesis is concentrated upon the electronic packaging in order to propose low-cost well-performing solutions in the millimeter-wave bands. Low Temperature Co-fired Ceramics (LTCC) is chosen to be the technological platform for this work with the objective to elaborate packages that include the DC feed network, high frequency transmission lines as well as the MMIC (Microwave Monolithic Integrated Circuit). Such a package can be closed by a lid in order to protect the chip. When it comes to millimeter-wave frequencies, miniaturization comes naturally since the dimensions are related to the wavelength. The miniaturization is advantageous but at the same time adds strong dimensional constraints. The transmission support is chosen to be the Grooved Laminated Waveguide (GLWG), a rectangular waveguide integrated in the LTCC, due to its good performance in terms of losses and isolation while at the same time having dimensions that allows a successful fabrication. The minimal dimensions will set the upper frequency limit of the GLWG. In this work, different devices have been produced and their electrical functioning has been confirmed up to 170 GHz. When the frequency goes up, dimensional difficulties are even more pronounced when it comes to the interconnection between the pads of the MMIC and of the GLWG. To realize this interconnection, we have proposed three new topologies using the flip chip concept from which passive measurement results are presented. This assembly type offers an advantageous wide band behavior. The last part of this thesis is centered on the transition between the GLWG and an external wave guide to which the package will be connected. One transition has been proposed, fabricated and measured. The encountered difficulties are discussed and improvements are proposed. To conclude this work, improvements on the fabrication technique of LTCC devices are presented. Fabrication steps have been added to the already approved steps, and design rules have been elaborated.
