Este trabalho de pesquisa apresenta uma proposta para um sistema de supervisão automatizada de processo dedicado à soldagem de componentes eletrônicos. Essa soldagem é realizada por forno de refusão de solda, o qual pertence ao processo de montagem de produtos eletrônicos com tecnologia de dispositivo de montagem em superfície (Surface Mounting Devide SMD). Esses produtos, para o caso estudado, são aplicados no ramo automotivo, o qual exige que o processo produtivo tenha características destacadas de repetibilidade, padronização, além da preservação do meio ambiente. Para atender essas características o mencionado processo emprega a tecnologia de solda sem chumbo (lead free) na soldagem de componentes. Essa tecnologia exige que o perfil térmico possua uma média de temperatura maior sobre os elementos submetidos ao processo de soldagem, quando comparado com o processo tradicional estanho-chumbo. Para atender essa exigência o sistema de supervisão proposto neste trabalho adquire informações relacionadas a temperaturas das zonas do forno, integridade de resistência de aquecimento, sistema de insuflamento de ar quente e velocidade de operação da esteira transportadora de placas. Essa aquisição é apresentada para o operador do sistema, por meio de uma Interface Homem-Máquina, com a meta de alertar sobre o atual estado do processo. Nessa interface é destacada a previsão de campos relacionados com registro contínuo das informações adquiridas, parametrização de informações de processo, alarmes visuais e sonoros. A avaliação sistêmica dessa proposta de monitoração de informações indica que se forem controladas todas as características críticas do forno poderá haver contribuição para a melhoria no aludido processo de produção especialmente no que se refere à qualidade da soldagem, bem como a integridade física de todos os componentes do produto. / This research presents a proposal for an automated supervision system of dedicated soldering process of electronic components. This soldering is accomplished by a reflow oven, which belongs to the process of assembly of electronic products with Surface Mounting Device (SMD) technology. These products, for the studied case, are applied in the utomotive branch, which demands that the productive process has outstanding characteristics of repeatability, standardization, beyond of the preservation of the environment. To assist those characteristics mentioned, this process uses the solder technology without lead (lead free) in the soldering of components. This technology demands that the thermal profile possesses an average of bigger temperature on the elements submitted to the soldering process, when compared with the traditional process tin-lead. To assist that demand the supervision system proposed in this work acquires information related with temperature of oven zones, integrity of heating resistance, blower system and speed of board transportation belts / conveyors. This acquisition is presented for system operator by means of Man-machine Interface, with the goal of to sensitize on the current state of the process. In that interface it is detached the forecast of fields related with continuous registration of the acquired information, make the process information on a parameter, visual and sonorous alarms. The systemic evaluation of this proposal indicates that if controlled all the critical characteristics of the oven it will be able to have contribution for the improvement in the alluded process of production especially in what refers to the quality of the product.

This graduation thesis addresses questions to thermal profile measurement of PBGA package during solder reflow process. The first part of thesis deals with problem of reflow process and reliability factors of solder joint connection. Next part analyses operation principles of thermocouples that are commonly used for temperature measurement. The experimental part deals with methods of thermocouples fixation during tests and measurements of dummy PBGA package. There was realized a method of dummy PBGA thermal profiles measurement and sample testing with and without simulated thermal load on PBGA package. The end of thesis concerns on possibilities of thermal profiles evaluation by using PWI method and thermal profile optimization of reflow process.

Orientador: Margarete Cristiane de Costa Trindade Amorim / Resumo: A investigação da interferência da cidade na composição da atmosfera próxima à superfície remonta ao século XIX. Os estudos pioneiros do clima urbano apresentaram considerações sobre as alterações da cidade e da agricultura nos climas dos lugares. Esse quadro de interferências gerou grande comprometimento da qualidade do ambiente, refletindo nas condições de vida das populações, pois as alterações climáticas influenciam no conforto térmico, na saúde e no desempenho humano. Especialmente no ambiente tropical, o desconforto térmico demanda adaptação via climatização dos ambientes internos, influenciando no maior aporte energético, além de não ser acessível por parte da população. Em contrapartida, os espaços externos estão sujeitos aos efeitos das ilhas de calor, derivadas das condições meteorológicas e das características urbanas (OKE, 1987). O clima urbano é entendido como o clima de um determinado espaço e sua urbanização (MONTEIRO, 1976), não existindo uma escala rígida para o diagnóstico deste fenômeno. Nesse sentido, as cidades médias e pequenas também mostram importantes alterações das suas condições pretéritas à urbanização e exibem relativas facilidades para uma investigação climática qualitativa, pois seus espaços reduzidos permitem a melhor diferenciação dos seus ambientes intraurbanos e existem possibilidades de intervenção e planejamento urbano nos novos espaços em expansão. Esta pesquisa teve como objetivo investigar o clima urbano de cidades do ambiente tropical ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The investigation of cities’ interference in the composition of the near-surface atmosphere dates back to the nineteenth century. Pioneering studies on the urban climate presented considerations regarding changes in cities and agriculture in the climates of the places. This situation of interference compromised to a large degree the quality of the environment, reflecting on the living conditions of the populations, as climate change has an impact on human thermal comfort, health, and performance. Particularly in the tropical environment, thermal discomfort demands adaptation via climate control of indoor environments, influencing the greater energy supply, besides not being accessible by the population. In contrast, outdoor spaces are subject to the effects of heat islands, derived from weather conditions and urban characteristics (OKE, 1987). The urban climate is understood as the climate of a given space and its urbanization (MONTEIRO, 1976), and there is no rigid scale for the diagnosis of this phenomenon. In this sense, small and medium-sized cities also show important changes in their conditions prior to urbanization and present relative ease for a qualitative climate investigation, as their small spaces allow a better differentiation of their intraurban environments, and there are possibilities of intervention and urban planning in the new expanding spaces. This research aimed to investigate the urban climate of cities in the tropical environment located in the western ... (Complete abstract click electronic access below) / Doutor

A referida pesquisa teve como finalidade utilizar ferramentas de geotecnologias para avaliar o comportamento térmico de diferentes tipos de superfícies urbanas e sua consequente contribuição na variação da temperatura do ar e no conforto térmico humano em ambientes abertos. Para o estudo do conforto térmico fez-se necessário avaliar o desempenho do modelo COMFA (modelo de conforto térmico ao ar livre) em prever o conforto térmico em condições de clima quente, uma vez que este modelo, até então, só havia sido testado em países de clima temperado. Assim, esta pesquisa foi realizada em duas etapas distintas: a primeira avaliou o desempenho do modelo COMFA, considerando fatores pessoais de adaptação e aclimatação em situações de clima ameno a calor intenso. De modo a obter o voto real dos individuos (Actual thermal Sensation - ATS), foram aplicados ao longo de 5 dias 467 questionários em condições variadas de clima e exposição ao sol. Posteriormente os valores de ATS obtido foram plotados com o conforto térmico previsto (Predict Thermal Sensation- PTS) gerados pelo modelo COMFA. Os dados foram processados e analisados na Universidade de Guelph (Canadá) onde contou -se com a contribuição dos autores do modelo. Comparando - se os resultados de pesquisas similares realizadas no Canadá, o estudo concluiu que há um importante fator de adaptação e aclimatação dos indivíduos, o que sugere a necessidade de ajustes à escala de interpretação da sensação térmica (PTS) correspondente. Assim, dentro das condições climáticas estudadas, o presente trabalho indicou um PTS onde o intervalo mais adequado para determinar a zona de neutralidade térmica seria entre 50 W/m² e 100 W/m² em estações quentes e entre 0 W/m² e 70W/m² para estações frias. Houve um claro ajustamento sazonal, onde a faixa de neutralidade térmica se movimente para mais ou para menos, de acordo com a expetativa e aclimatação das pessoas. Na segunda etapa, avaliou -se a diferença no nível de conforto térmico humano em duas áreas da cidade de Piracicaba- SP, bem distintas quanto a proporção entre a área vegetada e a área costruida. Utilizou-se uma estação meteorológica móvel para o registro da temperatura do ar ( TºC), da umidade ralativa do ar ( UR), a radiação solar (W/m²) e da velocidade do vento ( m/s). Nestas duas áreas amostrais também foram adquiridas imagens de alta resolução da videografia aérea multiespectral e imagens termais (temperatura de superfície) de uma cena de 1km x 1km. A partir disso, com a técnica da classificação supervisionada foram separados por classes as porcentagens dos diferentes tipos das superfícies urbanas. Também obteve-se mapas temáticos com valores da temperatura radiante da superfície urbana da cenas. De acordo com os resultados do trabalho, pôde-se constatar que a influência da cobertura de superfície das áreas monitoradas sobre as condições climáticas é significativa para o conforto térmico humano. / This research aimed to use geotechnology tools to evaluate the thermal behavior of different types of urban surfaces and their consequent contribution to the variation of air temperature and human thermal comfort in outdoor environments. To study the thermal comfort was necessary to evaluate the performance of the model COMFA (thermal comfort outdoor model) to predict the thermal comfort in hot weather conditions, since in this model, until then, was only been tested in temperate countries. Thus, this research was conducted in two stages: the first evaluated the performance of COMFA model, considering personal factors of adaptation and acclimatization in situations of mild to intense heat climate. In order to obtain the actual vote of individuals (Actual thermal Sensation - the ATS), were applied over 5 days 467 questionnaires during varied climate and sun exposure. Afterwards the ATS values obtained were plotted with the thermal comfort provided by the model COMFA (Predict Thermal Sensation). The data were processed and analyzed at the University of Guelph (Canada) with contributions from authors of the model. Comparing the results of similar surveys conducted in Canada, the study concluded that there is a significant factor of adapting and acclimatization of the subjects, which suggests the need for adjustments to the scale of interpretation of thermal sensation (PTS) correspondent. Thus, within the climatic conditions studied, this study indicated a PTS where the most appropriate for determining the zone of thermal neutrality would be range between 50 W / m² and 100 W / m² in warm seasons and between 0 W / m² and 70W / m² for cold seasons. There was a clear seasonal adjustment, where the range of thermal neutrality moves more or less, according to the expectation of the people and acclimatization. In the second stage, we evaluated the difference in the level of human thermal comfort in two areas of the city of Piracicaba-SP, distinct as the ratio of vegetated area and built area. We used a mobile station forecast to record the air temperature (T ºC) of relative humidity (RH), solar radiation (W/m²) and wind speed (m / s). These two sites were also obtained high-resolution images of multispectral aerial videography and thermal images (surface temperature) of a 1km x 1km scene. From this, using the technique of supervised classification were separated the percentages of different types of urban surfaces. Also was obtained thematic maps with values of radiant scenes of urban surface temperature. According to the results of the work, it can be stated that the influence of surface coverage of the monitored areas on climate conditions is significant for human thermal comfort.

Variability has become one of the vital challenges that the designers of integrated circuits encounter. variability becomes increasingly important. Imperfect manufacturing process manifest itself as variations in the design parameters. These variations and those in the operating environment of VLSI circuits result in unexpected changes in the timing, power, and reliability of the circuits. With scaling transistor dimensions, process and environmental variations become significantly important in the modern VLSI design. A smaller feature size means that the physical characteristics of a device are more prone to these unaccounted-for changes. To achieve a robust design, the random and systematic fluctuations in the manufacturing process and the variations in the environmental parameters should be analyzed and the impact on the parametric yield should be addressed. This thesis studies the challenges and comprises solutions for designing robust VLSI systems in the presence of variations. Initially, to get some insight into the system design under variability, the parametric yield is examined for a small circuit. Understanding the impact of variations on the yield at the circuit level is vital to accurately estimate and optimize the yield at the system granularity. Motivated by the observations and results, found at the circuit level, statistical analyses are performed, and solutions are proposed, at the system level of abstraction, to reduce the impact of the variations and increase the parametric yield. At the circuit level, the impact of the supply and threshold voltage variations on the parametric yield is discussed. Here, a design centering methodology is proposed to maximize the parametric yield and optimize the power-performance trade-off under variations. In addition, the scaling trend in the yield loss is studied. Also, some considerations for design centering in the current and future CMOS technologies are explored. The investigation, at the circuit level, suggests that the operating temperature significantly affects the parametric yield. In addition, the yield is very sensitive to the magnitude of the variations in supply and threshold voltage. Therefore, the spatial variations in process and environmental variations make it necessary to analyze the yield at a higher granularity. Here, temperature and voltage variations are mapped across the chip to accurately estimate the yield loss at the system level. At the system level, initially the impact of process-induced temperature variations on the power grid design is analyzed. Also, an efficient verification method is provided that ensures the robustness of the power grid in the presence of variations. Then, a statistical analysis of the timing yield is conducted, by taking into account both the process and environmental variations. By considering the statistical profile of the temperature and supply voltage, the process variations are mapped to the delay variations across a die. This ensures an accurate estimation of the timing yield. In addition, a method is proposed to accurately estimate the power yield considering process-induced temperature and supply voltage variations. This helps check the robustness of the circuits early in the design process. Lastly, design solutions are presented to reduce the power consumption and increase the timing yield under the variations. In the first solution, a guideline for floorplaning optimization in the presence of temperature variations is offered. Non-uniformity in the thermal profiles of integrated circuits is an issue that impacts the parametric yield and threatens chip reliability. Therefore, the correlation between the total power consumption and the temperature variations across a chip is examined. As a result, floorplanning guidelines are proposed that uses the correlation to efficiently optimize the chip's total power and takes into account the thermal uniformity. The second design solution provides an optimization methodology for assigning the power supply pads across the chip for maximizing the timing yield. A mixed-integer nonlinear programming (MINLP) optimization problem, subject to voltage drop and current constraint, is efficiently solved to find the optimum number and location of the pads.

Variability has become one of the vital challenges that the designers of integrated circuits encounter. variability becomes increasingly important. Imperfect manufacturing process manifest itself as variations in the design parameters. These variations and those in the operating environment of VLSI circuits result in unexpected changes in the timing, power, and reliability of the circuits. With scaling transistor dimensions, process and environmental variations become significantly important in the modern VLSI design. A smaller feature size means that the physical characteristics of a device are more prone to these unaccounted-for changes. To achieve a robust design, the random and systematic fluctuations in the manufacturing process and the variations in the environmental parameters should be analyzed and the impact on the parametric yield should be addressed. This thesis studies the challenges and comprises solutions for designing robust VLSI systems in the presence of variations. Initially, to get some insight into the system design under variability, the parametric yield is examined for a small circuit. Understanding the impact of variations on the yield at the circuit level is vital to accurately estimate and optimize the yield at the system granularity. Motivated by the observations and results, found at the circuit level, statistical analyses are performed, and solutions are proposed, at the system level of abstraction, to reduce the impact of the variations and increase the parametric yield. At the circuit level, the impact of the supply and threshold voltage variations on the parametric yield is discussed. Here, a design centering methodology is proposed to maximize the parametric yield and optimize the power-performance trade-off under variations. In addition, the scaling trend in the yield loss is studied. Also, some considerations for design centering in the current and future CMOS technologies are explored. The investigation, at the circuit level, suggests that the operating temperature significantly affects the parametric yield. In addition, the yield is very sensitive to the magnitude of the variations in supply and threshold voltage. Therefore, the spatial variations in process and environmental variations make it necessary to analyze the yield at a higher granularity. Here, temperature and voltage variations are mapped across the chip to accurately estimate the yield loss at the system level. At the system level, initially the impact of process-induced temperature variations on the power grid design is analyzed. Also, an efficient verification method is provided that ensures the robustness of the power grid in the presence of variations. Then, a statistical analysis of the timing yield is conducted, by taking into account both the process and environmental variations. By considering the statistical profile of the temperature and supply voltage, the process variations are mapped to the delay variations across a die. This ensures an accurate estimation of the timing yield. In addition, a method is proposed to accurately estimate the power yield considering process-induced temperature and supply voltage variations. This helps check the robustness of the circuits early in the design process. Lastly, design solutions are presented to reduce the power consumption and increase the timing yield under the variations. In the first solution, a guideline for floorplaning optimization in the presence of temperature variations is offered. Non-uniformity in the thermal profiles of integrated circuits is an issue that impacts the parametric yield and threatens chip reliability. Therefore, the correlation between the total power consumption and the temperature variations across a chip is examined. As a result, floorplanning guidelines are proposed that uses the correlation to efficiently optimize the chip's total power and takes into account the thermal uniformity. The second design solution provides an optimization methodology for assigning the power supply pads across the chip for maximizing the timing yield. A mixed-integer nonlinear programming (MINLP) optimization problem, subject to voltage drop and current constraint, is efficiently solved to find the optimum number and location of the pads.

A referida pesquisa teve como finalidade utilizar ferramentas de geotecnologias para avaliar o comportamento térmico de diferentes tipos de superfícies urbanas e sua consequente contribuição na variação da temperatura do ar e no conforto térmico humano em ambientes abertos. Para o estudo do conforto térmico fez-se necessário avaliar o desempenho do modelo COMFA (modelo de conforto térmico ao ar livre) em prever o conforto térmico em condições de clima quente, uma vez que este modelo, até então, só havia sido testado em países de clima temperado. Assim, esta pesquisa foi realizada em duas etapas distintas: a primeira avaliou o desempenho do modelo COMFA, considerando fatores pessoais de adaptação e aclimatação em situações de clima ameno a calor intenso. De modo a obter o voto real dos individuos (Actual thermal Sensation - ATS), foram aplicados ao longo de 5 dias 467 questionários em condições variadas de clima e exposição ao sol. Posteriormente os valores de ATS obtido foram plotados com o conforto térmico previsto (Predict Thermal Sensation- PTS) gerados pelo modelo COMFA. Os dados foram processados e analisados na Universidade de Guelph (Canadá) onde contou -se com a contribuição dos autores do modelo. Comparando - se os resultados de pesquisas similares realizadas no Canadá, o estudo concluiu que há um importante fator de adaptação e aclimatação dos indivíduos, o que sugere a necessidade de ajustes à escala de interpretação da sensação térmica (PTS) correspondente. Assim, dentro das condições climáticas estudadas, o presente trabalho indicou um PTS onde o intervalo mais adequado para determinar a zona de neutralidade térmica seria entre 50 W/m² e 100 W/m² em estações quentes e entre 0 W/m² e 70W/m² para estações frias. Houve um claro ajustamento sazonal, onde a faixa de neutralidade térmica se movimente para mais ou para menos, de acordo com a expetativa e aclimatação das pessoas. Na segunda etapa, avaliou -se a diferença no nível de conforto térmico humano em duas áreas da cidade de Piracicaba- SP, bem distintas quanto a proporção entre a área vegetada e a área costruida. Utilizou-se uma estação meteorológica móvel para o registro da temperatura do ar ( TºC), da umidade ralativa do ar ( UR), a radiação solar (W/m²) e da velocidade do vento ( m/s). Nestas duas áreas amostrais também foram adquiridas imagens de alta resolução da videografia aérea multiespectral e imagens termais (temperatura de superfície) de uma cena de 1km x 1km. A partir disso, com a técnica da classificação supervisionada foram separados por classes as porcentagens dos diferentes tipos das superfícies urbanas. Também obteve-se mapas temáticos com valores da temperatura radiante da superfície urbana da cenas. De acordo com os resultados do trabalho, pôde-se constatar que a influência da cobertura de superfície das áreas monitoradas sobre as condições climáticas é significativa para o conforto térmico humano. / This research aimed to use geotechnology tools to evaluate the thermal behavior of different types of urban surfaces and their consequent contribution to the variation of air temperature and human thermal comfort in outdoor environments. To study the thermal comfort was necessary to evaluate the performance of the model COMFA (thermal comfort outdoor model) to predict the thermal comfort in hot weather conditions, since in this model, until then, was only been tested in temperate countries. Thus, this research was conducted in two stages: the first evaluated the performance of COMFA model, considering personal factors of adaptation and acclimatization in situations of mild to intense heat climate. In order to obtain the actual vote of individuals (Actual thermal Sensation - the ATS), were applied over 5 days 467 questionnaires during varied climate and sun exposure. Afterwards the ATS values obtained were plotted with the thermal comfort provided by the model COMFA (Predict Thermal Sensation). The data were processed and analyzed at the University of Guelph (Canada) with contributions from authors of the model. Comparing the results of similar surveys conducted in Canada, the study concluded that there is a significant factor of adapting and acclimatization of the subjects, which suggests the need for adjustments to the scale of interpretation of thermal sensation (PTS) correspondent. Thus, within the climatic conditions studied, this study indicated a PTS where the most appropriate for determining the zone of thermal neutrality would be range between 50 W / m² and 100 W / m² in warm seasons and between 0 W / m² and 70W / m² for cold seasons. There was a clear seasonal adjustment, where the range of thermal neutrality moves more or less, according to the expectation of the people and acclimatization. In the second stage, we evaluated the difference in the level of human thermal comfort in two areas of the city of Piracicaba-SP, distinct as the ratio of vegetated area and built area. We used a mobile station forecast to record the air temperature (T ºC) of relative humidity (RH), solar radiation (W/m²) and wind speed (m / s). These two sites were also obtained high-resolution images of multispectral aerial videography and thermal images (surface temperature) of a 1km x 1km scene. From this, using the technique of supervised classification were separated the percentages of different types of urban surfaces. Also was obtained thematic maps with values of radiant scenes of urban surface temperature. According to the results of the work, it can be stated that the influence of surface coverage of the monitored areas on climate conditions is significant for human thermal comfort.

This master´s thesis deals with QFN packages soldering and technology procedures optimization. The aim of theoretical part is description of QFN packages, their assembly and reflow soldering on PCB in HONEYWELL. The aim of the practical part is to propose a method of measuring temperature and optimizing the thermal profiles of selected PCB with QFN packages by using convection (HONEYWELL) and infrared (BUT) reflow ovens. Comparison and evaluation of thermal profiles for 3 production PCBś with QFN packages using solder paste AIM NC257-2 were realised. The main part of master´s thesis are appearance evaluation of solder joints, preparing microsection and measuring intermetallic layers thickness by using the optical and the scanning electron microscopes, analysation and study of QFN defects created during soldering proces. These tests were performed with 2 production PCB´s. Optimization of SPI and soldering technology procedures where were analyzed QFN packages were processed on one type of PCB. Interesting part of this diplomma thesis is creating of the 3D heat transfer model of QFN package during the reflow soldering in SolidWorks.

The Diploma thesis is focused on reballing of BGA packages with the device PACE TF 2700. It describes the general types of BGA packages, their defects, importance of thermal management to the solder techniques, where it is also talked about the meaning of solders and fluxes for the joint. The work informs about the most common methods of reballing, the proper handling of components and the current situation with BGA stencils on the market. It briefly describes the device operation of PACE TF 2700, that is working on the convection and IR principle of heating components. It deals with the manufacturing of the template, dummy BGA packages, the test plates, creation of the thermo profile, comparing and examining the defects and their causes, which had the most significant impact on the results. The achievements would serve for comparing them with the results of the future laboratory exercises or as a subject for further works.

Graduation thesis is specialized on dilemma of the integrated circuits with ball grid array. Chapter two describes several types of packages and confrontation of their characteristics. Chapter three considers possibilities of corrections these boards bedded with packages, mounting and demounting of these packages, method of camera control and also inspection of the soldering process. Chapter four attend to practical measuring of thermal profiles and their optimalization.