L’étude a pour objectif l’amélioration de la fiabilité des assemblages électroniques à travers la mise en œuvre de drains composites aluminium/fibres de carbone. Le travail a consisté à 1) modéliser, par la méthode des éléments finis, l’influence des propriétés thermiques et mécaniques du matériau de semelle sur l’assemblage életronique ; 2) élaborer (par frittage sous charge uniaxiale, frittage flash et extrusion à chaud) des matériaux composites aluminium/fibres de carbone ; et 3) lier les microstructures observées aux paramètres des procédés d’élaboration ainsi qu’aux propriétés thermiques et mécaniques mesurées. / This study has been done in order to improve power electronic devices reliability using aluminium/carbon fibres composites. This work has consisted in 1) determining, using finite elements method, the thermal and mechanical influence of the electronic base plate material; 2) elaborating (using hot pressing, spark plasma sintering and hot extrusion) aluminium/carbon fibres composites; and 3) linking the microstructures observed to the elaboration parameters and to the thermomechanical properties measured.

L'objectif de nos études est d’appliquer la technique de radiométrie photothermique modulée, technique non intrusive et applicable à distance, pour d’une part, mesurer l'épaisseur et la diffusivité thermique d'une plaque, et d’autre part, caractériser une couche sur un substrat. Un modèle thermique du chauffage 3D a été développé avec prise en compte de l’échange thermique par convection dans le cas d'une plaque, et de la résistance thermique de l'interface dans le cas d'une couche sur un substrat. Une analyse de sensibilité des paramètres sur le déphasage et des études multiparamétriques ont été réalisées à l'aide d'un code de calcul développé sous Matlab. Des formules simples ont ainsi été déterminées pour mesurer l'épaisseur et la diffusivité thermique d'une plaque ainsi que le rapport des effusivités thermiques dans le cas d'une couche sur un substrat. Les formules établies pour les plaques ont été validées expérimentalement sur des plaques d’épaisseur variant de 100μm à 500μm pour différents métaux : inox 304L, nickel, titane, tungstène, molybdène, zinc et fer. L’incertitude de ces déterminations est inférieure à 10% pour l'épaisseur et inférieure à 15% pour la diffusivité thermique. La technique a ensuite été appliquée à des gaines de Zircaloy-4, qui représentent une application très intéressante dans le domaine du nucléaire : les résultats montrent que la présence de la couche d'oxyde, d’épaisseur quelques μm, n'a que très peu d’influence sur les déterminations de l'épaisseur et de la diffusivité thermique du Zircaloy-4. Le comportement du déphasage à hautes fréquences (> 1 kHz) ouvre de plus de nouvelles perspectives, avec la possibilité d’étendre le domaine d’application de la méthode aux couches semi-transparentes et aux couches très minces (inférieures au μm). / Modulated photothermal radiometry, a remote non-intrusive technique, was used to measure the thickness and the thermal diffusivity of a metal plate and to characterize a layer on a substrate. A thermal model of 3D heating was developed with considering the thermal exchange by convection for a plate and the thermal resistance of the interface for a layer on a substrate. The sensibility analysis and the multi-parameter studies on the phase shift were performed by the code developed with the Matlab software. Simple formulas were obtained to determine the thickness and the thermal diffusivity of a plate and the ratio of the thermal effusivities for a layer on a substrate. The obtained formulas were experimentally validated for 100 μm - 500 μm plate thickness of various metals (stainless steel 304L, nickel, titanium, tungsten, molybdenum, zinc and iron). The uncertainty of the measurements was lower than 10 % for thickness and lower than 15 % for thermal diffusivity determination. The same technique was applied in the study on Zircaloy-4 cladding that may be of particular interest for the nuclear industry. It was found that the presence of the oxide layer of some μm thickness had practically no effect on the thickness and the thermal diffusivity measurements of Zircaloy-4 cladding. However, the observed effect of a phase shift on high frequency (> 1kHz) may open new perspectives and widen the field of the method application for semi-transparent layers and for very thin layers (of less than μm thickness).

Optically-transparent solids have a significant role in many emerging topics of fundamental and applied research, in areas related to Applied Optics and Photonics. In the functional devices based on them, the presence of ‘time-varying temperature fields’ critically limit their achievable performance, when used particularly for high power laser-related tasks such as light-generation, light-amplification, nonlinear-harmonic conversion etc. For optimization of these devices, accurate knowledge of the material thermal parameters is essential. Many optical and non-optical methods are currently in use, for the reliable estimation of the thermal parameters. The thermal diffusivity is a key parameter for dealing with ‘transient heat transport’ related problems. Although its importance in practical design for thermal management is well understood, its physical meaning however continues to be esoteric. The present effort concerns with a few investigations on the “Optical interrogation of ‘transient thermal conduction’ in dielectric solids”. In dielectric solids, the current understanding is that the conductive heat transport occurs only through phonons relevant to microscopic lattice vibrations. Introducing for the first time, a virtual linear translator motion as the basis for heat conduction in dielectric materials, the present investigation discusses an alternative physical mechanism and a new analytical model for the transient heat conduction in dielectric solids. The model brings into limelight a ‘new law of motion’ and a ‘new quantity’ which can be defined at every point in the material, through which time-varying heat flows resulting in time-varying temperature. Physically, this quantity is a measure for the linear translatory motion resulting from transient heat conduction. For step-temperature excitation it bears a simple algebraic relation to the thermal diffusivity of the material. This relationship helps to define the thermal diffusivity of a dielectric solid as the “translatory motion speed” measured at unit distance from the heat source. A novel two-beam interferometric technique is proposed and corroborated the proposed concept with significant advantages. Two new approaches are introduced to estimate thermal diffusivity of optically transparent dielectric solid; first of them involves measurement of the position dependent velocity of isothermal surface and second one depend on the measurement of position dependent instantaneous velocity of normalized moving intensity points. A ‘new mechanism’ is proposed and demonstrated to visualize, monitor and interrogate optically, the ‘linear translatory motion’ resulting from the transient heat flow due to step- temperature excitation. Two new approaches are introduced, first one is ‘mark’ and ‘track’ approach, it involves a new interaction between sample supporting unsteady heat flow with its ambient and produces optical mark. Thermal diffusivity is estimated by tracking the optical mark. Second one involves measurement of instantaneous velocity of optical mark for different step-temperature at a fixed location to estimate thermal diffusivity. A new inverse method is proposed to estimate thermal diffusivity and thermal conductivity from the volumetric specific heat capacity alone through thought experiment. A new method is proposed to predict volumetric specific heat capacity more accurately from thermal diffusivity.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-08-17T17:30:45Z No. of bitstreams: 1 JOSÉ RICARDO FERREIRA OLIVEIRA – DISSERTAÇÃO (PPGEM) 2017.pdf: 2648257 bytes, checksum: 5e08d81aaa5973d7c6fd8bac23c313cc (MD5) / Made available in DSpace on 2018-08-17T17:30:45Z (GMT). No. of bitstreams: 1 JOSÉ RICARDO FERREIRA OLIVEIRA – DISSERTAÇÃO (PPGEM) 2017.pdf: 2648257 bytes, checksum: 5e08d81aaa5973d7c6fd8bac23c313cc (MD5) Previous issue date: 2017-11-30 / CNPq / A caracterização termofísica dos materiais utilizados na Engenharia é de grande importância para realização de projetos nas mais diversas áreas de conhecimento onde os fenômenos ligados aos processos de transferência de calor exercem um papel fundamental. A difusividade térmica é uma propriedade termofísica importantíssima na análise de problemas de difusão de energia térmica. Este trabalho teve como proposta a determinação desta propriedade utilizando um campo de temperatura periódico. Para isto, foi construído um dispositivo experimental com princípio de funcionamento no método de Angstrom, o qual faz uso de um fluxo de calor periódico de uma fonte controlada, gerando assim, um campo de temperatura periódico na amostra em teste. Termopares foram instalados nas amostras para captar os sinais de temperatura gerados pelo fluxo de calor periódico. A amplitude e a fase destes sinais foram obtidas por meio de um software de análise gráfica. O termopar mais próximo da fonte de calor foi adotado como referência, ao passo que a razão de amplitudes e a defasagem, entre os sinais térmicos registrados pelos demais termopares em relação ao registrado por àquele termopar , foram calculadas. Estes resultados foram utilizados em modelos matemáticos para determinar a difusividade térmica, que pode ser identificada ou atra vés da razão de amplitudes ou através da defasagem entre os perfis de temperatura. As amostras utilizadas neste trabalho foram de aço inox AISI 304, aço inox AISI 316 e de uma liga de memória de forma de níquel-titânio. Os valores de difusividade térmica identificados para estes materiais, quando foram comparados com valores disponíveis na literatura, obtiveram uma boa concordância, tendo em vista a faixa de incerteza apresentada. / Thermophysical characterization of materials used in engineering is very important for realization of projects in the most diverse areas of knowledge where the phenomena related to the process of heat transfer play an important role. Thermal diffusivity is a very important thermal property on the analysis of problems of diffusion of thermal energy. This work proposes the determination of this property using a periodic temperature field. For this, an experimental device was built with principle of operation in Angstrom’s method, which makes use of a periodic heat flow from a controlled source, thereby generating a periodic temperature field in the test sample. Thermocouples were installed on the samples for capture of signals generated by the periodic heat flow. Amplitude and phase of these signals were obtained by means of graphic analysis software. The thermocouple closest to the heat source was adopted as reference, and the ratio and phase lag, between the thermal signals registered by other thermocouples in relation to that registered by that thermocouple, were calculated. These results were utilized in mathematical models to determine the thermal diffusivity, whose identification can be performed either through the amplitude ratio or through the phase lag between the temperature profiles. Samples utilized in this work were stainless steel AISI 304, stainless steel AISI 316 and a shape memory alloy of nickel-titanium. Identified values of thermal diffusivity of these materials, when compared whit values available in literature obtained a good agreement, considering the range of uncertainty presented.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho, desenvolveu-se um sistema de detecção fotoacústico para medidas simultâneas e independentes dos sinais fotoacústicos dianteiro e traseiro, utilizando dois microfones e um único feixe de excitação. Utiliza-se a diferença de fase entre estes sinais para a determinação da difusividade térmica de materiais, com base na abordagem teórica da técnica da Diferença de Fase dos Dois Feixes (T2F). Na metodologia apresentada não há a necessidade de se alternar o feixe de excitação entre as faces da amostra. Esta característica torna mais rápido o procedimento de medida e simplifica o monitoramento automatizado de processos dinâmicos que afetam a difusividade térmica do material, como a cura de resinas poliméricas. É apresentado o procedimento utilizado para determinar a diferença entre as fases intrínsecas dos microfones e o método empregado para compensar tal diferença e, assim, obter a defasagem entre os sinais fotoacústicos dianteiro e traseiro. O sistema de detecção desenvolvido é avaliado em medidas de difusividade térmica de amostras metálicas (aço inoxidável AISI 304 e aço SAE 1020) e poliméricas (polipropileno e polietileno de baixa densidade). Os resultados obtidos concordam de forma satisfatória com dados disponíveis na literatura. Finalmente, a aplicação do sistema proposto ao monitoramento de cura de amostras de resina epóxi indicou sua potencialidade de acompanhar, em tempo real, este tipo de processo dinâmico. / In this work, a photoacoustic detection system was developed for simultaneous and independent measurements of both front and rear photoacoustic signals, using two microphones and a single beam illumination mode. The phase-lag between these signals is used in the determination of thermal diffusivity of materials, based on the theoretical approach of the Two-Beam Phase-Lag technique. In the experimental setup presented in this work there is no need to alternate the light beam between the sample surfaces. This feature provides faster measurements and simplify the automated monitoring of dynamic processes that affect the material thermal diffusivity, as crosslinking processes. The procedure to determine the difference between the intrinsic phases of the microphones is presented, as well as the method to compensate this difference and to obtain the phase-lag between front and rear photoacoustic signals. The developed detection system is tested in thermal diffusivity measurements of metallic (AISI 304 stainless steel and SAE 1020 steel) and polymeric (polypropylene and low-density polyethylene) samples. The results are in good agreement with the available literature values. Finally, the system here proposed is applied in studies of epoxy resin curing, which shows its potentiality for real-time monitoring of dynamic process.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho, desenvolveu-se um sistema de detecção fotoacústico para medidas simultâneas e independentes dos sinais fotoacústicos dianteiro e traseiro, utilizando dois microfones e um único feixe de excitação. Utiliza-se a diferença de fase entre estes sinais para a determinação da difusividade térmica de materiais, com base na abordagem teórica da técnica da Diferença de Fase dos Dois Feixes (T2F). Na metodologia apresentada não há a necessidade de se alternar o feixe de excitação entre as faces da amostra. Esta característica torna mais rápido o procedimento de medida e simplifica o monitoramento automatizado de processos dinâmicos que afetam a difusividade térmica do material, como a cura de resinas poliméricas. É apresentado o procedimento utilizado para determinar a diferença entre as fases intrínsecas dos microfones e o método empregado para compensar tal diferença e, assim, obter a defasagem entre os sinais fotoacústicos dianteiro e traseiro. O sistema de detecção desenvolvido é avaliado em medidas de difusividade térmica de amostras metálicas (aço inoxidável AISI 304 e aço SAE 1020) e poliméricas (polipropileno e polietileno de baixa densidade). Os resultados obtidos concordam de forma satisfatória com dados disponíveis na literatura. Finalmente, a aplicação do sistema proposto ao monitoramento de cura de amostras de resina epóxi indicou sua potencialidade de acompanhar, em tempo real, este tipo de processo dinâmico. / In this work, a photoacoustic detection system was developed for simultaneous and independent measurements of both front and rear photoacoustic signals, using two microphones and a single beam illumination mode. The phase-lag between these signals is used in the determination of thermal diffusivity of materials, based on the theoretical approach of the Two-Beam Phase-Lag technique. In the experimental setup presented in this work there is no need to alternate the light beam between the sample surfaces. This feature provides faster measurements and simplify the automated monitoring of dynamic processes that affect the material thermal diffusivity, as crosslinking processes. The procedure to determine the difference between the intrinsic phases of the microphones is presented, as well as the method to compensate this difference and to obtain the phase-lag between front and rear photoacoustic signals. The developed detection system is tested in thermal diffusivity measurements of metallic (AISI 304 stainless steel and SAE 1020 steel) and polymeric (polypropylene and low-density polyethylene) samples. The results are in good agreement with the available literature values. Finally, the system here proposed is applied in studies of epoxy resin curing, which shows its potentiality for real-time monitoring of dynamic process.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-08T12:29:33Z No. of bitstreams: 1 elaineaparecidacarvalho.pdf: 7755814 bytes, checksum: b31278b6963ad259e85e174cf59c5391 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-26T18:10:31Z (GMT) No. of bitstreams: 1 elaineaparecidacarvalho.pdf: 7755814 bytes, checksum: b31278b6963ad259e85e174cf59c5391 (MD5) / Made available in DSpace on 2017-06-26T18:10:31Z (GMT). No. of bitstreams: 1 elaineaparecidacarvalho.pdf: 7755814 bytes, checksum: b31278b6963ad259e85e174cf59c5391 (MD5) Previous issue date: 2013-03-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho, três diferentes materiais (vidros, filmes finos e nanofluidos) foram analisados com o objetivo de verificar mudanças nas propriedades térmicas e ópticas devido a presença de nanopartículas de metais nobres. Nos vidros e filmes, o crescimento de nanopartículas foi induzido através do tratamento térmico das amostras enquanto que nos nanofluidos, a nucleação das nanopartículas foi obtida através de um procedimento químico de uma única etapa. A formação das nanopartículas metálicas nestes materiais foi confirmada pelas imagens de microscopia eletrônica e pelo pico de plasmon superficial presente nos espectros de absorção. Espectros Raman foram obtidos com a finalidade de verificar se ocorreu alguma mudança estrutural. Medidas de lente térmica foram realizadas em todas as amostras, fornecendo os valores da difusividade térmica. As matrizes vítreas estudadas foram germanato (Ge02 - PbO) e telurito (Te02 - PbO-Ge02), dopadas com nanopartículas de prata e com os íons terras raras Érbio, Ytérbio e Túlio na forma trivalente. Foi verificado que ocorreu um aumento de 20 % e 8 % na difusividade térmica dos vidros germanatos e teluritos, respectivamente, devido a adição de nanopartículas de prata e que o tratamento térmico provocou a quebra de anéis de tetraedros formados nos vidros germanato. Os filmes finos contendo nanopartículas de ouro e prata foram crescidos em um substrato através da técnica de co-sputtering utilizando a matriz vítrea de germanato (Ge02 - PbO) como alvo. Os resultados indicam a formação de estruturas diferentes daquelas detectadas no vidro, além de apresentar mudanças no comportamento térmico em relação a matriz vítrea. Nos nanofluidos de ouro e prata foram observados um aumento de 20% e 16%, respectivamente, na difusividade térmica em relação a difusividade térmica água pura. / In this work, three different materials (glasses, thin films and nanofluids) were analysed to check the changes in their thermal and optical properties due to the presence of noble metal nanoparticles. In the glasses and films, the nucleation of nanoparticles was induced by thermal treatment of the samples while in the nanofluids the nanoparticles were obtained through one-step chemical reaction. The presence of metallic nanoparticles was confirmed by electron microscopy images and by surface plasmon peaks detected via absorption technique in the ultraviolet and visible region of the electromagnetic spectrum. In addition, Raman spectra were obtained to check structural changes. Thermal lens measurements were performed in all samples to obtain the respective thermal diffusivity. Studied vitreous system were germanate (Ge02 - PbO) and tellurite (Te02 - PbO-Ge02) doped with silver nanoparticles, rare earth ions, erbium, thulium and ytterbium in the trivalent form. It was found an increase of 20% and 8% in the thermal diffusivity of germanate and tellurite glasses, respectively, due to the addition of silver nanoparticles. It also verified that the thermal treatment has caused the break of Ge04 tetrahedra rings. Thin films containing gold and silver nanoparticles were grown by the co-sputtering technique using the germanate vitreous matriz (Ge02 - PbO) as target. Raman results show structural differences between thin films and the corresponding glasses. This was reflected in a different thermal behavior. In gold and silver nanofluids were observed an increase of 20% and 16% in the thermal diffusivity in comparison with the thermal diffusivity of pure water, respectively.

Thermal barrier coating (TBC) systems are widely used on gas turbine components to provide thermal insulation and oxidation protection. TBCs, incombination with advanced cooling, can enable the gas turbine to operate at significantly higher temperatures even above the melting temperature of the metallic materials. There is a permanent need mainly of environmental reasons to increase the combustion turbine temperature, hence new TBC solutions are needed.By using a liquid feedstock in thermal spraying, new types of TBCs can be produced. Suspension plasma/flame or solution precursor plasma spraying are examples of techniques that can be utilized for liquid feedstock thermal spraying.This approach of using suspension and solution feedstock, which is an alternative to the conventional solid powder feed stock spraying, is gaining increasing research interest, since it has been shown to be capable of producing coatings with superior coating performance.The objective of this research work was to explore relationships between process parameters, coating microstructure, thermal diffusivity and thermal conductivity in liquid feedstock thermal sprayed TBCs. A further aim was to utilize this knowledge to produce a TBC with lower thermal diffusivity and lower thermal conductivity compared to state-of-the-art in industry today, i.e. solid feed stock plasma spraying. Different spraying techniques, suspension high velocity oxy fuel,solution precursor plasma and suspension plasma spraying (with axial and radialfeeding) were explored and compared with solid feedstock plasma spraying.A variety of microstructures, such as highly porous, vertically cracked and columnar, were obtained. It was shown that there are strong relationships between the microstructures and the thermal properties of the coatings.Specifically axial suspension plasma spraying was shown as a very promising technique to produce various microstructures as well as low thermal diffusivity and low thermal conductivity coatings.

De nos jours, les matériaux composites sont très largement utilisés dans l’industrie aéronautique et aérospatiale car ils ont de très bonnes tenues mécaniques, mais ces matériaux comportent de fortes hétérogénéités dues aux fibres et aux liants qui les constituent. Ainsi, depuis de nombreuses années, l’équipe TIFC «Thermal Imaging Fields and Characterization » du département TREFLE de l’institut I2M développe des méthodes de mesure des propriétés thermophysiques de matériaux hétérogènes dans le plan ou dans l’épaisseur. Ces méthodes sont très variées du point de vue des méthodes inverses (transformée intégrale, double décomposition en valeurs singulières, …) ou expérimentale (Flash, diode laser, …). Le faible coût des diodes lasers et des systèmes de déplacement de miroirs galvanométriques ont permis de développer un système complet de scanner optique laser, monté sur un banc de mesure. Il permet de revisiter les différents types de sollicitations thermiques et de réaliser une infinité de combinaisons spatiotemporelles d’excitations thermiques par méthode laser. Ceci est une des principales originalités de ce travail. De nouvelles méthodes inverses basées sur la réponse thermique au point source impulsionnel et sur la séparabilité des champs de température ont été proposées. Ces méthodes ont permis d’estimer le tenseur de diffusivité thermique selon les axes principaux d’anisotropie, mais aussi hors des axes du repère de l’image, où il est possible de déterminer l’orientation des axes d’anisotropie, lorsque le transfert de chaleur s’effectue hors des axes du repère de l’image. Ces méthodes ont permis d’obtenir des résultats intéressants comptetenu de leur simplicité. De plus, elles ont permis d’obtenir des cartographies de diffusivités thermiques dans le plan car, comparées aux autres méthodes, elles permettent d’obtenir des estimations du tenseur de diffusivité thermique localement grâce à l’obtention d’une cartographie de flux thermique surfacique via le scanner optique laser. / Nowadays, composite materials are widely used in the aeronautic and aerospace industries because of their high mechanical resistance. However, they have a large heterogeneity due to the fiber and matrix they are made of. In this way, for many years, the TIC team «Thermal Imaging Fields and Characterization » from TREFLE department of I2M laboratory develops methods to measure thermal in-plane properties of heterogeneous materials such as inverses (integral transforms, double singular value decomposition…) or experimental (Flash, laser diode…) methods. The recent progress made in optical control, lasers and infrared (IR) cameras enables the development of a new scanning system (based on galvanometer-mirror) which allows the easy control of a laser hot spot spatial and temporal displacements over a plane surface. The low cost of laser diodes and optical control (galvanometric mirror) systems allows to develop a laser scanning system fixed on a test bench. We can revisit the different types of thermal excitation and realize infinite spatio-temporal combinations of thermal excitations by laser method. This is one of this thesis aims. New inverse methods based on the thermal response to an instantaneous point source heating, and temperature fields separability, have been proposed. These methods allow to estimate the thermal diffusivity tensor along the main axes of anisotropy, but also out of those axes, where it is possible to estimate the anisotropy axes orientation when the heat transfer takes place out of the image axes. These methods have produced interesting results in view of their simplicity. Moreover, they made it possible to obtain in-plane thermal diffusivities maps because, compared to the other methods, they allow to obtain, locally, thermal diffusivity tensor estimations by getting a surface heat flux map using the laser optical scanner.

Die fortschreitende Miniaturisierung von elektronischen Systemen begleitet von steigender Leistung und Funktionalität führt zur Erhöhung der Leistungsdichte. Um diesem Trend zu entsprechen, werden neue Entwärmungskonzepte benötigt, die wiederum neuartige Materialien und Materialverbünde fordern. Ein wichtiger Aspekt dieser Arbeit ist deshalb die Konzentration auf die für den Wärmetransport entscheidenden Materialien. Diese Arbeit befasst sich mit der Entwicklung von Methoden für die umfassende thermische Charakterisierung von den verschiedenen Materialien und Materialklassen, die in der Elektronikindustrie verwendet werden. Die Messsysteme wurden so entworfen und entwickelt, dass spezifische Anwendungsbedingungen berücksichtigt werden können, keine aufwändige Probenherstellung notwendig ist und gleichzeitig eine hohe Messgenauigkeit gewährleistet ist. Es wurden vier verschiedene Messsysteme innerhalb dieser Arbeit entwickelt und realisiert, die in ihrer Gesamtheit die Charakterisierung von fast allen Package-Materialien unter gewünschten Randbedingungen ermöglichen. Zahlreiche Materialien und Effekte wurden daraufhin im Rahmen dieser Arbeit mit den entwickelten Messsystemen untersucht und diskutiert. / The continuous miniaturization of electronic systems accompanied by increasing performance and functionality leads to an increase in power density. In order to comply this trend, new heat dissipation concepts are needed which demand new materials and material composites. An important aspect of this work is therefore the concentration on the materials that are decisive for the heat flow. This thesis deals with the development of Methods for comprehensive thermal characterization of the different materials and material classes used in the electronics industry. The measuring systems have been designed and developed in such a way that they enable to take into account specific application conditions, no costly sample preparation is necessary and at the same time high measuring accuracy is ensured. Four different measuring systems were developed and realized within this work, which, in their entirety, enable the characterization of almost all package materials under desired boundary conditions. Based on this, numerous materials and effects were investigated and discussed in the context of this work with the developed measurement systems.