The effect of joint strength of PbSn and AuSn solder in aging test for laser module packaging has been studied experimentally. The thermal conditions were aged at 150 ¢J for 1,4,9,16,25 and 36 days. It was found that the joint strength decreased as aging test time increased. The joint strength of PbSn solder with the gold coating on SUS304 substrate of 2 µm and 10 µm decreased about 17% and 28% after aging test, respectively. The joint strength of PbSn solder with the gold coating on SUS304 substrate of 2 µm and 10 µm decreased about 16% and 9% after aging test, respectively. we also presented the microstructure of the intermetallic compound ¡]IMC ¡^growth under aging test. Results showed that the thickness of the IMC increased after aging test. The growth thickness of the IMC from 1 to 36 days for the PbSn and AuSn solder were measured to be 5.26 to 34.37 and 0.48 to 1.64 µm, respectively. The joint strength decreased under aging test may be due to the crack and void defects increased within the solder. The crack and void defects in solder were observed by metallographic photos.

The joint strength and fracture surface of Sn80¢HAu20¢H and Sn20¢HAu80¢H solders in laser diode package under thermal aging testing were studied experimentally. The AuSn thin film solders were coated on the substrate by electro-plating technique. The Sn80¢HAu20¢H solder was melting point at 210¢J,while the Sn20¢HAu80¢Hsolder was melting point at 280¢J. During the processes of bonding substrate and Al2O3 together, the N2 and H2 gases were used to achieve the bonding. Then the specimens were aged at 150¢J for one, four, nine, sixteen, twenty-five, thirty-six and forty-nine days. We investigated the bonding strength, voids, IMC thickness and microstructure of the Sn80¢HAu20¢H and Sn20¢HAu80¢H solders. In addition, we also studied the comparison with the process of flux and fluxless. Under the forty-nine days of aging, the bonding strength of Sn80¢HAu20¢Hand Sn20¢HAu80¢H solders decreased from 34.3¢V to 26.0¢V and from 54.96¢V to 47.06¢V,respectively. Moreover,the IMC thickness of Sn80¢HAu20¢H and Sn20¢HAu80¢H solders increased from1.07£gm to 2.85£gm and from 0.83 £gm to 1.08 £gm, respectively. The Sn20¢HAu80¢H solders showed a better joint strength performance than Sn80¢HAu20¢H due to the less grown of IMC and superior mechanical properties of Au. The fluxless process exhibited the better joint strength performance due to the less grown of voids. In the study, by using the lead-free and fluxless process, the reliability of laser module package may be improved.

No description available.

Light-emitting diodes (LED) illumination takes considerable applications in nowadays daily lives due to the improvement on efficiency of the LED modules. The connections between the reliability and the lifetime, power efficiency, optical spectrum, and structure design of the LED modules are the major research topics. In this study, high-power LED modules encapsulated with different lens shapes after a thermal-aging test were studied experimentally and numerically. The results showed that the LED modules encapsulated with a hemispherical-shaped plastic lens exhibited a better lifetime due to their better thermal dissipation than those with cylindrical- or elliptical-shaped plastic lenses. In the case of 80¢J aging test, the lifetime of hemispherical-shaped lens was 1.5 times better than the cylindrical- or elliptical-shaped lenses. Decay of radiation pattern and optical spectrum of high-power LED modules fabricated by different manufacturers after a thermal-aging test were investigated experimentally and numerically. The results showed that the radiation pattern of the LED modules at the two view angles of ¡Ó (15o~75o) decreased more than the other angles as aging time increased. Due to the degradation of lens material after thermal aging, the center wavelength of the LED spectrum shifted 5 nm. Furthermore, the radius curvature of plastic lens was observed 6-70 £gm contraction as aging times increased. Both experimental and simulated results clearly indicated that improving the lens structure and lens material is essential to extend the operating life of the high-power LED modules. High-power phosphor-converted white-light-emitting diodes (PC-LEDs) with selected concentration and thickness of Ce:YAG phosphor-doped silicones were investigated to study the thermal degradation effect of the Ce:YAG phosphor-silicone layer. The experimental results showed that the lumen loss, chromaticity (CIE shift), and spectrum intensity reduction increased as the concentration of Ce:YAG phosphor doped silicone increased. We showed that 94% lumen loss was attributed to 5.5 wt% Ce:YAG doping and only 6% of the lumen loss was due to a 1mm thickness of silicone degradation. From practical points of view, we found that a lower doping concentration of the Ce:YAG phosphor in thin silicone is a better choice in terms of having less thermal degradation for use in packaging of the high-power PC-LEDs modules and is essential to extend the operating lifetime of the phosphor-based white LED modules.

Les composants hyperfréquences embarqués dans des satellites utilisent actuellement l’encapsulation hermétique dans des boîtiers métalliques ou céramiques. La très forte amélioration des matériaux organiques en termes de dégazage et d’impureté ionique notamment rend possible l’utilisation de solutions quasi-hermétiques pour l’environnement spatial. Les encapsulations plastiques ouvrent des perspectives avérées de gain de dimension et de coût. La validation d’une technologie d’encapsulation repose sur la réalisation d’essais de fiabilité normatifs (1000 heures à 85°C et 85% d’humidité relative). Ces essais sont applicables quels que soient le profil de stockage de la mission, le type d’encapsulation et la technologie des composants utilisés. Les conditions de réalisation de ces essais ne sont pas clairement définies, par exemple l’application ou pas d’un fort champ électrique au niveau du composant. Or ce seul paramètre devient prépondérant lorsque les conditions sont réunies pour permettre la mise en place de phénomènes de corrosion. Ces travaux de thèse se sont axés sur la compréhension des mécanismes de défaillance mis en jeu dans des tests de vieillissement accéléré en chaleur humide. Pour cela, une méthodologie a été mise en œuvre pour établir les signatures électriques en statique de composants défaillants de deux filières technologiques de MMICs GaAs. Ces tests ont été reproduits sur des composants avec et sans encapsulation par une résine époxyde chargée silice, déposée selon le procédé dam-and-fill. Ainsi, il a été possible de distinguer les défaillances liées à la dégradation intrinsèque des composants, de l’effet protecteur ou non de l’encapsulation plastique. En parallèle, le comportement d’échantillons de résines sous différentes ambiances de chaleur humide a été testé et une modélisation a été proposée pour prédire leur prise d’humidité. Concernant l’effet de l’encapsulation par dam-and-fill, les résultats obtenus ont été contradictoires et dépendant des lots de composants. Ces résultats sont à pondérer par la taille restreinte de l’échantillonnage des files de test. En effet, pour la technologie représentative de cette étude, la présence d’une encapsulation plastique, pour un premier lot de composants, a eu tendance d’une part, à ne pas éviter ni même retarder l’apparition de fuites électriques, et d’autre part à aggraver ces dégradations, au point de mener à des défaillances dans la majorité des cas. De plus, des doutes subsistent sur la qualité de ce lot, notamment celle de la passivation. Pour un second lot de composants testés de technologie identique, il a été observé une amélioration de la résistance à l’humidité des composants encapsulés, vis-à-vis des puces nues. L’analyse de défaillance des composants encapsulés est extrêmement difficile car il faut pouvoir accéder aux défauts à la surface, voire sous la surface, du composant protégé. Une solution alternative a donc été cherchée afin de contourner les problèmes posés par la présence du matériau d’encapsulation. La nouvelle approche proposée combine la thermographie infrarouge avec la méthode du point chaud, l’imagerie en optique et l’analyse aux rayons X. Le défaut est tout d’abord localisé par la face avant, malgré la présence de la résine d’encapsulation. Ensuite, la transparence du substrat GaAs aux infrarouges permet des observations par la face arrière du composant. Une méthodologie de préparation relativement simple et rapide a pu être proposée et sa faisabilité démontrée. / Microwave devices for satellite applications are encapsulated in hermetic packages as metal or ceramic housings. The strong improvement of organic materials, especially outgassing and ionic impurity characteristics, makes it possible to use them as non-hermetic packaging solutions for space environment. Plastic encapsulations open proven gain perspectives of miniaturization and cost. The validation of an encapsulation technology is based on the achievement of standard reliability tests, typically 1000 hours at 85°C and 85% of relative humidity. Such tests are applicable regardless of the mission storage profile, devices and packaging technology. Moreover, the conditions of these tests are not clearly defined, e.g. the application or not of a strong electric field to the component. Yet this single parameter becomes dominant when the conditions are met to allow corrosion mechanisms, e.g. by the presence of condensed water and ionic contamination. This thesis focused on understanding the failure mechanisms that can occur during accelerated aging tests in high temperature and high humidity environment. For this work, a methodology has been implemented to establish DC electrical signatures of two different AsGa MMIC technologies. These tests were replicated on components with and without encapsulation by a silica-filled epoxy resin, dispensed by the dam-and-fill process. Thus, it was possible to distinguish failures due to the intrinsic degradation of the components from the effective protection or not of the plastic encapsulation. In parallel, the behavior of resin samples under different moist and heat atmospheres has been tested and a modeling was proposed to predict their moisture uptake. Concerning the effect of the dam-and-fill encapsulation technology, the results were contradictory and dependent of components batch. These results are to balance by the relatively limited size of the sampling for each test series, with and without encapsulation. Indeed, for the representative technology of this work, the presence of dam&fill encapsulation on a first batch of components has tended on one hand not to avoid nor even to delay the appearance of electric leakage, and on the other hand to aggravate these damages in the point to lead to failures in most of cases. Furthermore, doubts remain on the quality of this batch, especially regarding the passivation. For a second batch of devices with the same technology, an improvement of the humidity resistance was observed for encapsulated devices, compared to bare devices. In the failure analysis process of encapsulated devices, it is not possible to access directly to the observation of a defect at its surface. We therefore sought an alternative to overcome the problems represented by the encapsulating materials. A new approach was proposed. It combined infrared thermography method in hot spot mode, X-ray imaging and optical observations. We first located the defect from the front side of the encapsulated device. Then, the transparency of the AsGa substrate allowed infrared observations by the back side of the component. A relatively rapid and simple methodology was proposed and its feasibility demonstrated.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2018-07-10T18:02:49Z No. of bitstreams: 1 DISSERTAÇÃO Alexsandro Martins da Silva.pdf: 297395 bytes, checksum: 65d3b63d699f4425cb634f0012fb96c4 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-07-16T17:08:22Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO Alexsandro Martins da Silva.pdf: 297395 bytes, checksum: 65d3b63d699f4425cb634f0012fb96c4 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-07-16T17:17:52Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO Alexsandro Martins da Silva.pdf: 297395 bytes, checksum: 65d3b63d699f4425cb634f0012fb96c4 (MD5) / Made available in DSpace on 2018-07-16T17:18:03Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO Alexsandro Martins da Silva.pdf: 297395 bytes, checksum: 65d3b63d699f4425cb634f0012fb96c4 (MD5) Previous issue date: 2016-06-03 / Para oferecer aos agricultores sementes de soja com qualidade e na quantidade demandada, as empresas sementeiras devem implementar eficientes processos de controle interno de qualidade, visando aferir a constantemente a germinação e o vigor das sementes. A presente pesquisa teve como objetivo averiguar o processo de controle de qualidade interno na Sementes São Francisco Rio Verde, Goiás. O trabalho foi realizado em laboratório de empresa sementeira na cidade de Rio Verde - GO. Foram utilizados 272 lotes de sementes de soja da cultivar NA 5909 RG, categoria S1, da safra 2014/2015. Os testes avaliados foram: tetrazólio précondicionado por 16 horas, envelhecimento acelerado por 72 horas, teste de germinação, teste de solo e emergência em areia. Os resultados demonstraram que os testes de envelhecimento acelerado e tetrazólio são confiáveis no controle de qualidade de lotes de soja. Conclui-se que os lotes apresentaram vigor e viabilidade satisfatórios, porém, o teste de germinação 180 dias após a colheita, demonstrou queda da viabilidade. / To provide soybean farmers with quality and quantity demanded, the seed companies should implement efficient internal quality control processes to assess the constantly germination and seed vigor. This study aimed to verify the internal quality control process in soybean seed company, in Rio Verde, Goiás. The essay was carried out in laboratory of a seed company in the Rio Verde-GO city. Were used 271 soybean seeds lots of the cultivar IN 5909 RG, category S1 cultivated in the agricultural year of 2014/2015. The tests evaluated were tetrazolium test with preconditioned for 16 hours, accelerated aging test for 72 hours, standard germination test, soil test and emergence in sand. The results showed that the accelerated aging test and tetrazolium test are reliable for use in intern quality control of soybean seeds lots. It has concluded that the lots had satisfactory vigor and viability, however, the germination test 180 days after harvested decreased in viability.

Made available in DSpace on 2014-08-20T13:44:29Z (GMT). No. of bitstreams: 1 dissertacao_alexandro_de_paula.pdf: 1347086 bytes, checksum: 5f7aa723fd96d4d6ee7beb8f49b68039 (MD5) Previous issue date: 2012-11-01 / The main goal of this study was to determine the best harvesting time of seed capsule so that the tobacco seed (Nicotiana tabacum L.) presents the best germination percentage and vigor, seeking a combination of maturity, vigor and germination. The study was conducted in the 2010/2011 crop season, at the Agronomic Center of Universal Leaf Tobacco Company, in Rio Pardo, RS, using the hybrid seed of Virginia type ULT 163,. Five sampling periods were established as treatment in a field of commercial production of tobacco seeds (T1 - 30% dry capsules and green sepals, T2 - 90% dry capsules and green sepals; T3 - dried capsules and dried sepals; T4 - 50 % dry stalk; T5 - 100% dry stalk) with eight replicates each treatment. There were germination and vigor, first germination and accelerated aging. It was found that the tobacco harvest seeds from hybrid cultivar ULT 163 may be performed without significant changes in germination and vigor among treatments T3 to T5 consisting of sepals and capsule brown in color until the total drying peduncle. / O objetivo deste trabalho foi verificar qual o melhor momento de colheita da cápsula de sementes de modo que a semente de tabaco (Nicotiana tabacum L.) apresente o maior vigor e a maior porcentagem de germinação, buscando uma combinação entre maturidade, vigor e germinação. O trabalho foi desenvolvido no Centro Agronômico da empresa Universal Leaf Tabacos LTDA., em Rio Pardo, RS, utilizando o híbrido de semente tipo Virgínia ULT 163, na safra 2010/2011. Estabeleceram-se cinco momentos de colheita como tratamentos em uma lavoura para produção comercial de sementes de tabaco (T1 30% das capsulas secas e sépalas verdes; T2 90% das capsulas secas e sépalas verdes; T3 capsulas secas e sépalas secas; T4 50% pedúnculo seco; T5 100% pedúnculo seco), com oito repetições cada. Realizaram-se testes de germinação e de vigor - primeira contagem de germinação e envelhecimento acelerado. Verificou-se que a colheita das sementes de tabaco da cultivar híbrida ULT 163 pode ser realizada sem alterações significativas na germinação e no vigor entre os tratamentos T3 a T5 que consiste da cápsula e sépalas na cor marrom até a secagem total do pedúnculo.

Ces travaux de thèses présentent un protocole expérimental d’évaluation de la fiabilité des transistors bipolaire à double hétéro-jonction submicroniques sur substrat InP. Les mécanismes de défaillances observés ont été mis en évidence grâce à ce protocole qui présente trois étapes : activation, détection et localisation des mécanismes de défaillance. Les tests de vieillissement accéléré ont été réalisés sur les TBH de structure hexagonale avec une base en InGaAs ou en GaAsSb ainsi que les structures TLM. Grâce à l’analyse électrique via la modélisation compacte, nous établissons les premières hypothèses sur l’origine physique des mécanismes de dégradation. Pour les transistors avec une base InGaAs, par exemple, les mécanismes de défaillance mis en évidence sont localisés:- A la périphérie d’émetteur entrainant ainsi une augmentation du courant de base pour VBE<0,6 V pour les tests sous contrainte thermique ainsi que sous contraintes thermique et électrique.- A la jonction base-émetteur, provoquant l’augmentation du courant de base et de collecteur respectivement pour VBE>0,6 V et 0.2<VBE<0,8 V.- Au niveau du contact ohmique d’émetteur, entrainant une dégradation des courants pour VBE>0,8 V. Cette diminution du courant est plus visible sur le courant de collecteur.Ces hypothèses ont été validées avec l’analyse physique 2D avec le logiciel TCAD Sentaurus. Des signatures électriques similaires ont été observées dans la bibliographie par de plusieurs auteurs. / This work presents the implementation of an experimental procedure to evaluate the failure mechanisms of submicron Heterojunction Bipolar Transistor on InP substrate. This procedure presents 3 steps: activation, detection and localization of the failure mechanisms. The accelerated aging tests have been used to active the failure mechanisms on hexagonal shape HBTs with InGaAs or GaAsSb base together with TLM. Due to the electrical analysis through the compact modelling, we established the first hypothesis about the origin of the failure mechanisms. For example, on InGaAs HBT, the failure mechanisms observed are located:- At the emitter sidewall. This mechanism leads to the increase of the base current for VBE<0.6 V- At the base-emitter junction leading to the increase of base and collector current for VBE>0,6 V and 0.2<VBE<0,8 V respectively.- And the ohmic contact layer leading to the collector current decrease for VBE>0.8 V.These hypotheses were validated by 2D physical simulation using TCAD Sentaurus. The same electrical signatures of the failure mechanisms are observed in literature.

The dissertation thesis with the topic „Simulation Modelling of Electrical Drives for Selected Critical Applications“ focuses on the area of given applications in civil aviation. The selected application that the thesis deals with is an electrically driven and electronically controlled fuel pump supplying fuel to an aviation motor of the APU type. The thesis gives a comprehensive description of the design cycle of the unit and demonstrates implementing all the required critical functions. In the course of the design of the unit modern techniques in mathematical modelling, simulation, verification, monitoring and prediction of the operation status of airborne equipment were uses to the utmost extent. The purpose of these was to show the suitability of their application with regard to decreasing design time and cost, increasing lifetime and servicing intervals, as well as increasing user comfort and decreasing price. At the same time the required reliability was to be kept. The thesis also aims to prove and verify the suitability of using electronically commutated dc motors in critical applications in civil aviation. To reach this goal, it is necessary to design a robust drive control which would meet the given reliability requirements.

The dissertation thesis with the topic „Simulation Modelling of Electrical Drives for Selected Critical Applications“ focuses on the area of given applications in civil aviation. The selected application that the thesis deals with is an electrically driven and electronically controlled fuel pump supplying fuel to an aviation motor of the APU type. The thesis gives a comprehensive description of the design cycle of the unit and demonstrates implementing all the required critical functions. In the course of the design of the unit modern techniques in mathematical modelling, simulation, verification, monitoring and prediction of the operation status of airborne equipment were uses to the utmost extent. The purpose of these was to show the suitability of their application with regard to decreasing design time and cost, increasing lifetime and servicing intervals, as well as increasing user comfort and decreasing price. At the same time the required reliability was to be kept. The thesis also aims to prove and verify the suitability of using electronically commutated dc motors in critical applications in civil aviation. To reach this goal, it is necessary to design a robust drive control which would meet the given reliability requirements.