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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The effect of rework on brittle fractures in lead free solder joints : The growth of intermetallic compounds during rework and its effects

Dornerus, Elin January 2009 (has links)
Saab Microwave Systems, SMW is a supplier of radar systems. The circuit boards that are operating in their radars have components which solder joints contains lead. However, the EU directive RoHs and WEEE are causing SMW to prepare for a transition to lead free solder joints. The objective of this thesis is to gain deeper knowledge of lead free solder joints. Brittle fractures in solder joints is a type of failure that might increase in a transition to lead free solder joints. The brittle fractures are induced by the creation of the intermetallic phases which are formed during soldering. The amount and composition of the intermetallics affects the mechanical strength of the joint. An intermetallic layer is thickened during heat exposure as during soldering, thermal aging and rework. The focus of this thesis was to investigate how rework affect the brittleness of the lead free solder joint and thereby how the intermetallic layers change depending on chemical composition, design and reflow cycles. Two types of components and two types of solder materials (SnPb and SAC305) were studied. To study the mechanical properties of the joint a shear testing device was used. This is a way of measuring the reliability of the joint when subjected to mechanical shock. The intermetallic layers were examined in a Scanning Electron Microscope and the fracture surfaces were studied in a optical microscope, a scanning electron microscope and a stereomicroscope. The heat spread over the board where examined by soldering thermocouples to the board and plotting the values of time and temperature. The results showed that the rework process did not have any significant impact of the intermetallic growth. The adjecent and distant components were not damaged during rework. A lead free rework process can therefor be preformed successfully at SMW. The intermetallic layers formed at the interface between the a lead free solder and a nickel finish grew faster than an intermetallic layer formed between a leaded solder and a nickel finish. The presence of nickel could therefore have a more negative effect on the intermetallic growth rate for the lead free material compared to the leaded.
22

Möjligheter och hinder för att utöka omfattningen av RoHS-direktivet / Expanding the Scope of the RoHS Directive : Prospects and Obstacles

Segerkvist, Stina January 2005 (has links)
<p>The RoHS Directive was introduced in order to restrict hazardous substances in Electrical and Electronic Equipment, EEE. It currently restricts the use of six hazardous substances/compounds; cadmium, lead, mercury, hexavalent chromium, PBB, and PBDE. The RoHS Directive currently includes category 1-7 and 10 in the categories of EEE listed in Annex 1A to the WEEE-Directive (Waste of EEE). The aim with the report is to investigate and elucidate prospects and obstacles to increase the scope of RoHS. This report mainly considers the inclusion of product categories 8 (Medical Devices) and 9 (Monitoring and Control Instruments). </p><p>In order to fulfil the aim eight questions were formulated, that shall be answered in the report. In order to find the knowledge of and attitude towards RoHS of manufacturers, retailers, and importers of products falling under category 8 and 9, a questionnaire was sent to 80 companies, of which 25 answered. The answers showed that many of the companies did not know of RoHS before the questionnaire was sent out. The majority did not consider that their product category needed a longer time period to find alternatives for the applications where any of the in RoHS restricted substances were used, compared with the other categories in annex 1A to WEEE. Of the companies that answered on the questionnaire the majority had less than 50 employees. The companies in the study had limited knowledge of the contents of their products, they bought the function rather than the contents. </p><p>One important conclusion in this report is that only a few of the companies in category 8 and 9 are likely to keep using non compliant components for a long time if they use standard electronic equipment irrespective if they intend to readjust their production according to the RoHS Directive or not. The reason is that most subcontractors will be forced by the customers, mainly the larger ones, to readjust their production. They certainly will not keep two production lines. A paradox problem that can arise for small and medium sized companies, the majority of those answering the questionnaire were, is to get access to compliant components before the RoHS Directive is put into force. These companies order such small batches that it is unrealistic to order them from the original manufacturer, who usually is located in Asia. The small and medium sized companies usually buy their components from middlemen/grossists in Europe and Sweden. These grossist in many cases have large stocks with non-compliant components that they want to sell out before RoHS Directive is put into force from the 1st July 2006. </p><p>The RoHS Directive has been critized for restricting lead, but different studies show that the alternatives to e.g. Lead gives only slightly worse results, which by way of introduction can be expected from a new technology compared with an old, more investigated. The work with the report has also revealed a lack in communication and cooperation not only between the different stakeholders in electronic industry: retailers, importers, manufacturers and subcontractors, but also between industry, customers and authorities. The RoHS Directive may improve the communication and cooperation between these different actors.</p>
23

The effect of rework on brittle fractures in lead free solder joints : The growth of intermetallic compounds during rework and its effects

Dornerus, Elin January 2009 (has links)
<p>Saab Microwave Systems, SMW is a supplier of radar systems. The circuit boards that are operating in their radars have components which solder joints contains lead. However, the EU directive RoHs and WEEE are causing SMW to prepare for a transition to lead free solder joints. The objective of this thesis is to gain deeper knowledge of lead free solder joints.</p><p>Brittle fractures in solder joints is a type of failure that might increase in a transition to lead free solder joints. The brittle fractures are induced by the creation of the intermetallic phases which are formed during soldering. The amount and composition of the intermetallics affects the mechanical strength of the joint. An intermetallic layer is thickened during heat exposure as during soldering, thermal aging and rework.</p><p>The focus of this thesis was to investigate how rework affect the brittleness of the lead free solder joint and thereby how the intermetallic layers change depending on chemical composition, design and reflow cycles. Two types of components and two types of solder materials (SnPb and SAC305) were studied.</p><p>To study the mechanical properties of the joint a shear testing device was used. This is a way of measuring the reliability of the joint when subjected to mechanical shock. The intermetallic layers were examined in a Scanning Electron Microscope and the fracture surfaces were studied in a optical microscope, a scanning electron microscope and a stereomicroscope. The heat spread over the board where examined by soldering thermocouples to the board and plotting the values of time and temperature.</p><p>The results showed that the rework process did not have any significant impact of the intermetallic growth. The adjecent and distant components were not damaged during rework. A lead free rework process can therefor be preformed successfully at SMW. The intermetallic layers formed at the interface between the a lead free solder and a nickel finish grew faster than an intermetallic layer formed between a leaded solder and a nickel finish. The presence of nickel could therefore have a more negative effect on the intermetallic growth rate for the lead free material compared to the leaded.</p>
24

Möjligheter och hinder för att utöka omfattningen av RoHS-direktivet / Expanding the Scope of the RoHS Directive : Prospects and Obstacles

Segerkvist, Stina January 2005 (has links)
The RoHS Directive was introduced in order to restrict hazardous substances in Electrical and Electronic Equipment, EEE. It currently restricts the use of six hazardous substances/compounds; cadmium, lead, mercury, hexavalent chromium, PBB, and PBDE. The RoHS Directive currently includes category 1-7 and 10 in the categories of EEE listed in Annex 1A to the WEEE-Directive (Waste of EEE). The aim with the report is to investigate and elucidate prospects and obstacles to increase the scope of RoHS. This report mainly considers the inclusion of product categories 8 (Medical Devices) and 9 (Monitoring and Control Instruments). In order to fulfil the aim eight questions were formulated, that shall be answered in the report. In order to find the knowledge of and attitude towards RoHS of manufacturers, retailers, and importers of products falling under category 8 and 9, a questionnaire was sent to 80 companies, of which 25 answered. The answers showed that many of the companies did not know of RoHS before the questionnaire was sent out. The majority did not consider that their product category needed a longer time period to find alternatives for the applications where any of the in RoHS restricted substances were used, compared with the other categories in annex 1A to WEEE. Of the companies that answered on the questionnaire the majority had less than 50 employees. The companies in the study had limited knowledge of the contents of their products, they bought the function rather than the contents. One important conclusion in this report is that only a few of the companies in category 8 and 9 are likely to keep using non compliant components for a long time if they use standard electronic equipment irrespective if they intend to readjust their production according to the RoHS Directive or not. The reason is that most subcontractors will be forced by the customers, mainly the larger ones, to readjust their production. They certainly will not keep two production lines. A paradox problem that can arise for small and medium sized companies, the majority of those answering the questionnaire were, is to get access to compliant components before the RoHS Directive is put into force. These companies order such small batches that it is unrealistic to order them from the original manufacturer, who usually is located in Asia. The small and medium sized companies usually buy their components from middlemen/grossists in Europe and Sweden. These grossist in many cases have large stocks with non-compliant components that they want to sell out before RoHS Directive is put into force from the 1st July 2006. The RoHS Directive has been critized for restricting lead, but different studies show that the alternatives to e.g. Lead gives only slightly worse results, which by way of introduction can be expected from a new technology compared with an old, more investigated. The work with the report has also revealed a lack in communication and cooperation not only between the different stakeholders in electronic industry: retailers, importers, manufacturers and subcontractors, but also between industry, customers and authorities. The RoHS Directive may improve the communication and cooperation between these different actors.
25

Sino-EU Trade Relations and the Environment: The Influence of the European Union`s Environmental Directives on China

Ibitz, Armin 26 July 2011 (has links)
Volumes of trade between the European Union and China have increased tremendously over the last decades, with the EU becoming China`s largest trading partner. Among the academic world there are serious concerns about the impacts of trade on national environmental regulation setting. There is fear that international trade will not only put advanced nations under strong competitive pressure to lower their environmental standards in order to stay competitive (race to the bottom) but also provide developing nations no incentives to strengthen their environmental protection measures as this would carry costs and reduce their global competitiveness (stuck at the bottom). In contrast to that believe, some scholars, such as David Vogel, argue that engaging in international trade can ¡V under certain assumptions ¡V result in tighter national regulation setting among trading partners (trading-up). This study sets out to analyze the linkage of trade and environmental standards between two major trading powers ¡V the EU and China. China`s integration with the world economy has spurred concerns among environmentalists as it was feared that the country`s national environmental regulatory system will be kept at low levels due to competitiveness considerations. However, China, the opposite can be observed. The EU has adopted strict environmental directives in several areas, and China has upgraded its environmental regulatory system. This study aims to find answers to the question if in the case of trade between the EU and China a situation of trading-up can be identified. In order to bring in domestic as well as international developments, the study applies a two-level games approach. The research is based on recent environmental directives that have been adopted by the EU. A selection of three directives forms the basis of the case studies: the Restriction of Hazardous Substances (RoHS), car emissions standards, and the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH). The study provides insights into how China is affected by these external regulations, how it responded to them and how it tries to utilize them to boost its economic development and enhance the quality of its environment. As the study reveals, European environmental directives have positive impacts on China`s national environmental regulatory setting processes, since the EU regulations not only raise the awareness of the issue among China`s policy makers and public interest groups but they also called for responses from affected domestic constituents. The external regulations raised the stakes of numerous domestic actors which then had to decide how to react adequately. All in all, the study concludes that EU environmental directives have worked in favor of stricter regulation setting in China.
26

Ökonomische Analyse der Rückgewinnung von hochwertigen Metallen aus elektrischen und elektronischen Altgeräten in Deutschland

Greif, Steffi 03 December 2009 (has links) (PDF)
Die vorliegende Ausgabe beschäftigt sich mit dem Thema „Ökonomische Analyse der Rückgewinnung von hochwertigen Metallen aus elektrischen und elektronischen Altgeräten in Deutschland“. Elektro- und Elektronikgeräte sind aus dem täglichen Leben nicht mehr wegzudenken; die Unternehmen entwickeln und produzieren immer leistungsfähigere Produkte, wobei durch die immer schnelleren und kurzlebigeren Innovationszyklen die Abfallberge ausgedienter Elektro(nik)geräte beständig wachsen. Mit Inkrafttreten des Elektro- und Elektronikgerätegesetz am 24. März 2005 werden alte Elektro(nik)geräte zukünftig getrennt gesammelt und weitgehend verwertet. Neu ist, dass die Hersteller mehr Verantwortung für ihre Produkte übernehmen und zur Verwertung der getrennt gesammelten Elektro- und Elektronik-Altgeräten verpflichtet sind. Das Elektro- und Elektronikgerätegesetz geht zum einen aus der europäischen Richtlinie über die Entsorgung von Elektro- und Elektronik-Altgeräten (WEEE) und zum anderen aus der europäischen Richtlinie über die Verwendung bestimmter gefährlicher Stoffe in Elektro- und Elektronikgeräten (RoHS) hervor und gilt als Reaktion auf die wachsenden Elektro(nik)schrott-Berge. Für die Unternehmen der Entsorgungs- und Recyclingbranche ergeben sich mit diesen gesetzlichen Neuerungen neue Chancen auf Weiterentwicklung ihres Geschäftsfeldes. Besonderes Augenmerk gilt den Demontageunternehmen, mit deren Hilfe erst die gesetzlichen Forderungen, hinsichtlich der zu erzielenden Rückgewinnungsquoten und der notwendigen selektiven Behandlung einiger Baugruppen, erfüllt werden können. Die Rückgewinnung hochwertiger Metalle aus Elektro(nik)schrott bedarf im Hinblick der Preissteigerungen auf den Rohstoffmärkten höchster Priorität. Mit Etablierung eines Sekundärrohstoffmarktes kann ein rohstoffarmes Land wie Deutschland der Abhängigkeit des Importes von Primärrohstoffen signifikant entgegenwirken.
27

Fiabilité des assemblages sans plomb en environnement sévère

Berthou, Matthieu 21 September 2012 (has links) (PDF)
Le mémoire porte sur l'étude de la fiabilité des assemblages utilisant des alliages de brasure sans-plomb en environnement sévère pour des applications électroniques. Une méthode de préparation métallographique fiable et reproductible en vue de l'analyse microstructurale est présentée. L'effet du vieillissement thermique statique sur l'évolution microstructurale de billes de brasure en SAC, la tenue à la fatigue mécanique des assemblages brasés et l'étude de l'endommagement thermomécanique sont développés. Le seul effet notable constaté après vieillissement thermique est l'augmentation des épaisseurs des intermétalliques de contact. A la suite de sollicitations mécaniques, les ruptures sont plus souvent observées dans les pistes que dans les brasures, et ne permettent pas d'incriminer des éléments de la microstructure brasée comme facteurs déterminant de propagation des fissures. Les sollicitations thermomécaniques conduisent à une recristallisation, et les fissures se propagent alors le long des joints de grains recristallisés.
28

Contribution à l'étude, la mise en œuvre et à l'évaluation d'une solution de report de puce de puissance par procédé de frittage de pâte d'argent à haute pression et basse température

Le Henaff, François 29 January 2014 (has links) (PDF)
Ces travaux s'intègrent dans la recherche de solutions alternatives aux alliages de brasure pour les assemblages de puissance. De par les propriétés intrinsèques de l'argent et les premiers travaux publiés, le frittage de pâte d'argent a été sélectionné comme technique d'assemblage pour être étudiée et évaluée. Après avoir effectué un état de l'art sur la structure d'un module de puissance, sur les différentes techniques d'assemblage, la fiabilité des assemblages et le frittage, différents essais ont été menés en partenariat avec les projets FIDEA et ASPEEC. Ils nous ont permis de définir des procédés d'assemblages, de caractériser thermiquement et mécaniquement les assemblages frittés et d'évaluer la fiabilité de ces assemblages par des essais expérimentaux et des simulations numériques. Ces travaux nous ont permis au final de réaliser un prototype d'assemblage double face fonctionnel aux propriétés thermomécaniques supérieures à celles d'un assemblage brasé.
29

ライフサイクル的観点からみた電気機器の化学物質管理

髙橋, 一彰 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23185号 / 工博第4829号 / 新制||工||1754(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 酒井 伸一, 教授 米田 稔, 准教授 平井 康宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
30

Ökonomische Analyse der Rückgewinnung von hochwertigen Metallen aus elektrischen und elektronischen Altgeräten in Deutschland

Greif, Steffi 03 December 2009 (has links)
Die vorliegende Ausgabe beschäftigt sich mit dem Thema „Ökonomische Analyse der Rückgewinnung von hochwertigen Metallen aus elektrischen und elektronischen Altgeräten in Deutschland“. Elektro- und Elektronikgeräte sind aus dem täglichen Leben nicht mehr wegzudenken; die Unternehmen entwickeln und produzieren immer leistungsfähigere Produkte, wobei durch die immer schnelleren und kurzlebigeren Innovationszyklen die Abfallberge ausgedienter Elektro(nik)geräte beständig wachsen. Mit Inkrafttreten des Elektro- und Elektronikgerätegesetz am 24. März 2005 werden alte Elektro(nik)geräte zukünftig getrennt gesammelt und weitgehend verwertet. Neu ist, dass die Hersteller mehr Verantwortung für ihre Produkte übernehmen und zur Verwertung der getrennt gesammelten Elektro- und Elektronik-Altgeräten verpflichtet sind. Das Elektro- und Elektronikgerätegesetz geht zum einen aus der europäischen Richtlinie über die Entsorgung von Elektro- und Elektronik-Altgeräten (WEEE) und zum anderen aus der europäischen Richtlinie über die Verwendung bestimmter gefährlicher Stoffe in Elektro- und Elektronikgeräten (RoHS) hervor und gilt als Reaktion auf die wachsenden Elektro(nik)schrott-Berge. Für die Unternehmen der Entsorgungs- und Recyclingbranche ergeben sich mit diesen gesetzlichen Neuerungen neue Chancen auf Weiterentwicklung ihres Geschäftsfeldes. Besonderes Augenmerk gilt den Demontageunternehmen, mit deren Hilfe erst die gesetzlichen Forderungen, hinsichtlich der zu erzielenden Rückgewinnungsquoten und der notwendigen selektiven Behandlung einiger Baugruppen, erfüllt werden können. Die Rückgewinnung hochwertiger Metalle aus Elektro(nik)schrott bedarf im Hinblick der Preissteigerungen auf den Rohstoffmärkten höchster Priorität. Mit Etablierung eines Sekundärrohstoffmarktes kann ein rohstoffarmes Land wie Deutschland der Abhängigkeit des Importes von Primärrohstoffen signifikant entgegenwirken.

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