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Analýza vlivu pouzdření na izolační vlastnosti / Analyze of Packaging Impact on Insulating propertiesPulec, Jiří January 2009 (has links)
Modern analog systems processing signals with very small amplitude are prone to distortion, which is caused by leakage between signal traces. Causation of this is contamination of insulating gap, which insulates these traces. Goal of this thesis is to design and manufacturing of test structure, which allows classification of influence of contamination on substrate on leakage, and another goal is classification of technologiacal processes in light of contamination of substrate with electroactive inpurities. Based on results of this experiments are defined rules leading to optimizing of properties of manufactured structures. Attention is applied to ceramic substrates with conductive traces which are created with thick film technology.
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Roztékavost bezolovnatých pájek na keramických substrátech / Wetting of lead-free solders on ceramic substratesLipavský, Lubomír January 2014 (has links)
This master's thesis deals with issue of lead-free soldering in protective atmosphere with focus on wetting test. Theorethical part is focused on the types of lead-free solders, wettability tests performed on solder joints, different types of soldering or comparison of influence of the base material in regards to the wetting of the solder. The goal of practical part is testing and comparison of spreadability of selected lead-free solder on two conductive surfaces with different concentration of oxygen in protective nitrogen atmosphere. Testing has been performed on ceramic substrate which differs this method from others, performed on organic substrate. For an over-melted solder, the crystal-growth on surface in regards to protective atmosphere concentration is shown.
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Packaging of a High Power Density Point of Load ConverterGilham, David Joel 29 March 2013 (has links)
Due to the power requirements for today's microprocessors, point of load converter packaging is becoming an important issue. Traditional thermal management techniques involved in removing heat from a printed circuit board are being tested as today's technologies require small footprint and volume from all electrical systems. While heat sinks are traditionally used to spread heat, ceramic substrates are gaining in popularity for their superior thermal qualities which can dissipate heat without the use of a heat sink. 3D integration techniques are needed to realize a solution that incorporates the active and components together. The objective of this research is to explore the packaging of a high current, high power density, high frequency DC/DC converter using ceramic substrates to create a low profile converter to meet the needs of current technologies.
One issue with current converters is the large volume of the passive components. Increasing the switching frequency to the megahertz range is one way to reduce to volume of these components. The other way is to fundamentally change the way these inductors are designed. This work will explore the use of low temperature co-fired ceramic (LTCC) tapes in the magnetic design to allow a low profile planar inductor to be used as a substrate. LTCC tapes have excellent properties in the 1-10 MHz range that allow for a high permeability, low loss solution. These tapes are co-fired with a silver paste as the conductor. This paper looks at ways to reduce dc resistance in the inductor design through packaging methods which in turn allow for higher current operation and better heavy load efficiency. Fundamental limits for LTCC technologies are pushed past their limits during this work. This work also explores fabrication of LTCC inductors using two theoretical ideas: vertical flux and lateral flux. Issues are presented and methods are conceived for both types of designs. The lateral flux inductor gives much better inductance density which results in a much thinner design.
It is found that the active devices must be shielded from the magnetic substrate interference so active layer designs are discussed. Alumina and Aluminum Nitride substrates are used to form a complete 3D integration scheme that gives excellent thermal management even in natural convection. This work discusses the use of a stacked power technique which embeds the devices in the substrate to give double sided cooling capabilities. This fabrication goes away from traditional photoresist and solder-masking techniques and simplifies the entire process so that it can be transferred to industry. Time consuming sputtering and electroplating processes are removed and replaced by a direct bonded copper substrate which can have up to 8 mil thick copper layers allowing for even greater thermal capability in the substrate. The result is small footprint and volume with a power density 3X greater than any commercial product with comparable output currents. A two phase coupled inductor version using stacked power is also presented to achieve even higher power density.
As better device technologies come to the marketplace, higher power density designs can be achieved. This paper will introduce a 3D integration design that includes the use of Gallium Nitride devices. Gallium Nitride is rapidly becoming the popular device for high frequency designs due to its high electron mobility properties compared to silicon. This allows for lower switching losses and thus better thermal characteristics at high frequency. The knowledge learned from the stacked power processes gives insight into creating a small footprint, high current ceramic substrate design. A 3D integrated design is presented using GaN devices along with a lateral flux inductor. Shielded and Non-Shielded power loop designs are compared to show the effect on overall converter efficiency. Thermal designs and comparisons to PCB are made using thermal imaging. The result is a footprint reduction of 40% from previous designs and power densities reaching close to 900W/in3. / Master of Science
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Influência da absorção de água e rugosidade de substratos cerâmicos e da adição de fíler na aderência de argamassas de revestimentoValentini, Paôla 23 March 2018 (has links)
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Previous issue date: 2018-03-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Diversos fatores influenciam a durabilidade de argamassas de revestimento, sendo alguns deles: a absorção de água, porosidade e rugosidade da superfície do substrato; a execução, com o preparo ou não do substrato, a forma de aplicação e as condições de cura da argamassa; as condições climáticas, decorrentes da ação do vento, umidade e temperatura; e a própria argamassa com seus componentes. Partindo deste contexto, esta pesquisa tem como objetivo avaliar fatores relacionados ao substrato e à argamassa que influenciam na resistência de aderência à tração de sistemas de revestimento. O programa experimental buscou avaliar a influência da absorção de água total, da absorção por capilaridade e da rugosidade de três substratos cerâmicos e também da adição de fíler na argamassa, na resistência de aderência à tração de sistemas de revestimento. Os substratos cerâmicos foram queimados nas temperaturas de 800°C, 900°C e 1000°C, sendo que, das 144 peças cerâmicas do estudo, metade receberam aplicação de hidrofugante. Sobre as peças cerâmicas foram aplicadas argamassas confeccionadas com areia natural de rio e cimento Portland CP II-Z-32, no traço 1:3, em massa, com e sem adição de 5% de pó de quartzo. A partir dos resultados encontrados observou-se que a maior resistência de aderência à tração foi obtida nos blocos cerâmicos com temperatura de queima de 800°C, que apresentam simultaneamente maior rugosidade e maior absorção capilar de água. Verificou-se também que a adição de fíler à argamassa aumentou a resistência de aderência quando aplicada sobre os blocos de maior rugosidade, não sendo observado o mesmo comportamento nos blocos de baixa rugosidade. De um modo geral, o uso de hidrofugante sobre as peças cerâmicas diminuiu os resultados de resistência de aderência além de alterar a forma de ruptura dos revestimentos. / The durability of coating mortars applied on substrates are influenced by the water absorption, porosity and roughness of the substrate surface; the preparation of the coating´s substrate, the method used to apply and the cure conditions of the mortar; beyond the climatic conditions, through the wind, humidity and temperature; and the mortar itself with its components. Based on this context, this research aims to evaluate factors related to the coating´s substrate and the rendering mortar that influence the adhesion strength of mortar coating systems. The experimental program aimed to evaluate the influence of total water absorption, capillary absorption and roughness of three ceramic substrates, as well as the use of filler in the mortar, in the adhesion strength of mortar coating systems. The ceramic substrates were burned at 800°C, 900°C and 1000°C, and of the 144 ceramic pieces of the study, 72 were painted with water repellent. The coating mortars were made with natural river sand and Portland cement CP II-Z-32, in the proportion 1: 3 (by mass), with and without adding 5% of quartz filler. It was observed that the highest tensile strength was obtained with the substrates of ceramic blocks burned at 800°C, which simultaneously present the higher roughness and higher water absorption. The use of filler in the mortar composition increased the adhesion strength when applied on the blocks of greater roughness. In general, the use of water repellent on the ceramic substracts decrease the adhesion strength of mortar coating systems and modify the kind of rupture of the coatings.
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ESTUDO DA INTERFACE ENTRE BLOCOS CERÂMICOS E ARGAMASSAS DE CHAP ISCO / STUDY OF THE INTERFACE BETWEEN CERAMIC BLOCKS AND SLURRY MOR TARCarvalho, Denizard Paulo 21 July 2016 (has links)
The analysis of adhesion mechanisms between mortar lining and porous substrates has been the target of
innumerous researchers due to its importance in ensuring system performance. Based on the theoretical reference
of the topic, this work of experimental nature aimed to analyze the influence of the superficial topography of
ceramic blocks in bonding slurry mortars and their relationship with the set of characteristics of fine aggregates
that make up slurry mortars. Initially, the substrates and component materials of the mortars were characterized
according to the Brazilian Association of Technical Standards; afterwards, characterization tests of fresh and
hardened mortars were carried out. In the testing phase, the blocks received the slurry mortars. The experimental
variables studied were: three types of ceramic blocks (ceramic sealing block with smooth surfaces, ceramic
sealing block with horizontal grooved surfaces, and ceramic sealing block with vertical grooved surfaces); and
two types of slurry mortars (one was prepared with coarse sand and the other with medium sand). Thus, six
interfaces were evaluated through aspects of bonding strength and permeability and absorption by the pipe
method. In order to observe the extent of adhesion and involvement of the grains of sand through the paste of
the slurry mortars, interface analyses were conducted through observation by magnifying glass and petrographic
microscope. The characteristics of the sands that influence the performance of fresh and hardened slurry mortars
were analyzed, with emphasis on the textural parameters of the sands, which were evaluated with the aid of
petrographic analysis. Results showed that there is direct correlation between the extent of adhesion provided by
the grooves of the blocks, and bond tensile strength, made possible by the fluid nature of the slurry mortar.
Therefore, this indicates the strong influence of the type of ceramic block on results of bond strength. On the
other hand, the study of the characteristics of the sands, represented mainly by the granulometric composition,
density, unitary mass, void content, degrees of roundness and sphericity, and mineralogy, proved to be useful in
order to understand the role of the fine aggregates in the performance of the slurry mortar. Additionally, we
observed that the tensile bonding strength was higher for the slurry mortars with coarse sand than with medium
sand, when comparing the same type of block, although the tests have pointed to non-significant differences.
This fact can be explained by the small difference between some of the characteristics of the sand used; however,
the coarse sand studied seems to provide greater integration of the grains involved by the mortar paste, which
was indicated by the degree of roundness. Moreover, it was also possible to observe direct relations in achieving
results when comparing the permeability and absorption by the pipe method with the initial rate of absorption
test (IRA) and extended IRA test. The final observation is that the basic treatment using slurry mortar can provide
several benefits: increased roughness of the base, increased tensile bonding strength, adjustment of the suction
capacity. This way, it was possible to homogenize the absorption of water by the substrate, thus avoiding
different screeding times and performance for the lining layer. Thus, the treatment of the base with the use of
slurry mortar can increase the performance and durability of the mortar lining. / A análise dos mecanismos de aderência entre argamassas de revestimento e substratos porosos tem sido alvo de
muitos pesquisadores, devido à importância que tem para garantir o desempenho do sistema. Com base no
referencial teórico sobre o tema, este trabalho de natureza experimental teve como objetivo principal analisar a
influência da topografia superficial de blocos cerâmicos na aderência de argamassas de chapisco e a sua relação,
ainda, com o conjunto de características dos agregados miúdos que compõem as argamassas de chapisco.
Inicialmente, os substratos e os materiais componentes das argamassas foram caracterizados através do grupo de
normas da Associação Brasileira de Normas Técnicas; na sequência, foram realizados ensaios de caracterização
das argamassas nos estados fresco e endurecido. Na fase de testes, os blocos receberam as argamassas de
chapisco. As variáveis experimentais estudadas foram: três tipos de blocos cerâmicos (bloco cerâmico de
vedação com faces lisas, bloco cerâmico de vedação com faces ranhuradas horizontais, e bloco cerâmico de
vedação com faces ranhuradas verticais); e dois tipos de argamassas de chapisco (uma elaborada com areia grossa
e outra com areia média). Dessa forma, surgiram seis interfaces que foram avaliadas através de aspectos
relacionados à resistência de aderência à tração e à permeabilidade e absorção pelo método do cachimbo. Na
intenção de observar a extensão de aderência e o envolvimento dos grãos de areia pela pasta das argamassas de
chapisco, foram feitas análises da interface através da observação por lupa estereoscópica e microscópio
petrográfico. Foram pesquisadas as características das areias que influem no desempenho das argamassas de
chapisco em seu estado fresco e endurecido, com ênfase nos parâmetros texturais das areias, avaliados com
auxílio da análise petrográfica. Os resultados mostraram que há correlação direta entre a extensão de aderência,
proporcionada pelas ranhuras dos blocos cerâmicos e a resistência de aderência à tração, possibilitada pela
natureza fluida da argamassa de chapisco, indicando, assim, a forte influência do tipo de bloco cerâmico nos
resultados de aderência à tração. De outro lado, o estudo das características das areias, representadas,
principalmente, pela composição granulométrica, massa específica, massa unitária, índice de vazios, graus de
arredondamento e esfericidade e mineralogia revelou-se útil no sentido de compreender o papel dos agregados
miúdos perante o desempenho das argamassas de chapisco. Notou-se que a resistência de aderência à tração foi
maior para as argamassas de chapisco com areia grossa do que com areia média, quando se compara um mesmo
tipo de bloco, embora os testes tenham apontado diferenças não significativas. Esse fato pode ser explicado pela
pouca diferença entre algumas das características das areias utilizadas; porém, a areia grossa estudada parece
proporcionar um maior entrosamento dos grãos envolvidos pela pasta da argamassa, indicado pelo grau de
arredondamento. Foram observadas, ainda, relações diretas na obtenção de resultados quando se compara a
permeabilidade e absorção pelo método do cachimbo com o ensaio do índice de absorção inicial de água (AAI)
e AAI estendido. A constatação final é de que o tratamento de base através do emprego de chapisco pode
proporcionar vários benefícios: aumento da rugosidade da base, aumento da resistência de aderência à tração e
regulagem da capacidade de sucção. Possibilitando, com isso, homogeneizar a absorção de água por parte do
substrato, evitando diferentes tempos de sarrafeamento e desempeno para a camada de revestimento. Assim, o
tratamento da base com uso do chapisco pode aumentar o desempenho e a durabilidade dos revestimentos de
argamassa.
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Nanášení kovové vrstvy na keramické substráty pro úpravu povrchových vlastností / Tailoring of physical properties of ceramic surface by the metallic layer depositionDvorský, Vojtěch January 2019 (has links)
The master thesis focuses on the preparation of nickel coating on ceramic (Al2O3) substrate. The deposition of nickel was carried out by the electroless plating method in bath at various kinetic conditions. An impact of varied size, shape and roughness on the quality of the coated surface was investigated. The main goal was to find optimized conditions of the plating process of the thin metal coatings. Prepared nickel coatings were analysed by SEM, EDX analysis, mechanical profilometry and the plating bath was analysed by UV-VIS spectrophotometry. The continuous nickel coatings were achieved by modifying the deposition process, and the kinetic mechanism of experimental conditions was described.
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