Abstract Ammonia (NH3) is one of valuable chemicals which is commonly used in manufacturing the fertilizer, synthetic fiber, synthetic plastics, and dynamites, and is used in the factories such as papermaking, textile mill, camera and electrical. NH3 is also a typical pollutant which is found to be emitted from industrial processes, agriculture areas and livestock farm. It causes burn damage due to the corrosion and has a long-term impact on human bronchus. This study was to investigate the performance and kinetics in oxidation of ammonia by using a method of selective catalytic oxidation (denoted by SCO) over a series catalysts of Cu/Ce . The major parameters were performed at the following conditions: initial concentration NH3 of influent in ranging from 500 ppm to 1000 ppm, temperatures ranging from 150¢J to 500¢J, oxygen content in inlet stream in ranging from 4¢Hto 20¢Hand humidity in ranging from 1¢Hto 20¢H(or an absolute humidity of 607 ppm-12136 ppm). In the first stage experiments, the purpose was to select a best catalyst, which had the great activity and highest selectivity on nitrogen. The catalysts used in this work were prepared into three types in the following: Cu/La/Ce (molar ratio: 8/1/1, 7/1/2, 7/2/1, 6/1/3, 6/2/2 and 6/3/1), Cu/La (molar ratio: 6/4, 7/3, 8/2 and 9/1) and Cu/Ce (molar ratio: 6/4, 7/3, 8/2 and 9/1); total numbers of catalysts were 14. Test results showed the molar ratio 6:4 of Cu/Ce catalyst was found to have the best activity and selectivity to convert NH3 in this work. The second stage experiments were carried to investigate the effect of parameters on conversion of NH3 over a Cu/Ce catalyst of molar ratio 6:4. The conversion of NH3 in process of SCO increased with operation conditions such as the going up of temperature, and the increasing both of oxygen content and of residence time. The lower conversion of NH3 was achieved by an increasing on initial concentration of NH3, space velocity and humidity. The third stage experiments were conducted to investigate the effect of operation period on deactivation of NH3 over the above catalyst. At constant initial concentration of NH3, oxygen content and space velocity for 30 hr continuously, we found Cu/Ce catalyst had an excellent stability in conversion of NH3. Further tests by XRD, SEM and EA were determined. The kinetics of SCO over a Cu/Ce catalyst of molar ratio 6:4 in oxidation of NH3, using differential method, was found that a pseudo-first order reaction could be described by Mars-Van Krevelend model. An equation of destruction efficiency in terms of NH3 was obtained, and a good fitting was got between the predicted and the experimental values.

Two most useful families of copper CVD precursors that have been utilized widely are the Cu(I) and Cu(II) £]-diketone complexes. The Cu(II)precursors require the use of an external reducing agent such as hydrogen to deposit copper films, i.e. CuII(£]-diketonate)2 + H2 ¡÷ Cu0+2 £]-diketonate. The Cu(I) precursors deposit pure copper films without the use of an external agent via a disproportionation reaction that produces a Cu(II)£]-diketonate in conjunction with other organic byproducts, i.e. 2CuI(£]-diketonate)L ¡÷ Cu0+ CuII(£]-diketonate)2+2L where L is a typical Lewis base neutral ligand. However, Do those ligands resulting from the dissociation of the precursors simply desorb intact from the substrate or the growing films, or react further on the surface? To understand the surface chemistry of these ligands may provide better knowledge for designing more superior precursors and improvement of fabrication processes. Cu(hfac)(VTMS) and Cu(hfac)(MHY) are the most promising Cu(I) precursors, as shown in Scheme 1.1. Here we report studies on the chemistry of VTMS, MHY and hfacH on a Cu(111) surface. It should be noted that the hfacH is the simplest molecule containing the hfac, so we use it as a reference for £]-diketonate ligand. The Cu(111) single crystal was used to mimic the reactivity of these ligands on a growing Cu film during copper CVD. In situ analysis of ligand surface chemistry is carried out by TPD/R (temperature-programmed desorption/reaction) and RAIRS (reflection adsorption infrared spectroscopy) to elucidate plausible reaction mechanisms by which ligands decompose and eventually lead to impurity incorporation into the growing films, and to suggest means of minimizing such reactions.

Abstract Ammonia is one of valuable chemicals which are commonly used in various industrial factors. It is also a typical pollutant, and has a long-term impact on human health for toxicity characteristics. This study was to investigate the performance, product selectivity and kinetics in oxidation of ammonia solution in WAO process over Cu/ACF catalyst. The operation parameters in continuous WAO process were performed as follows: initial concentration of ammonia in ranging from 200 ppm to 1000 ppm, pH at 12, velocity of influent at below 3.0 ml/min, temperature ranging from 443K to 463K and pressure at 3.0 MPa. In the experiments of catalyst selection, we decided to use 5% Cu/ACF catalyst for its high conversion and selectivity in oxidation of ammonia. A conversion of 95.42% in oxidation of ammonia was achieved under 463K and the product selectivity of N2 was raised from 53% to 85%. We found that Cu/ACF and ACF catalysts both had the good conversion and selectivity in oxidation of ammonia in WAO process. In the long-term test of catalyst stability, Cu/ACF had a bad stability after 48 hours reaction in WAO process. The tests such as XRD, SEM and EA were also determined. The kinetics of WAO over Cu/ACF catalyst in oxidation of ammonia using Power-Rate Law was presented. The apparent reaction order and activated energy were obtained.

Abstract The purpose of this study was to investigate the removal performance in oxidation of ammonia solution, synthesized concentration in range of 200 mg/l -1000 mg/l, in continuous WAO process over Cu/La/Ce catalyst. The operation parameters in WAO process were performed as follows: reaction temperature, influent velocity, initial concentration of ammonia and oxygen pressure. During the first stage WAO test, ammonia conversion only reached to 40.1% under the conditions performed as follows: initial concentration of ammonia in 400 mg/l, 12 of pH, 453 K of temperature, 3.0 MPa of total pressure and 3.0 ml/min of influent velocity. In the second stage experiments conducted by 453 K, pH 12, 3.0MPa and 400 mg/l, the ammonia conversion was above 86.2% over catalyst in WAO process. In addition, the conversion of ammonia were found to be 89%, 82.6%, 81.6% and 79.3% when the initial concentration were regulated in 200, 400, 800 and 1000 mg/l respectively; 91.4% conversion of ammonia could be obtained when temperature was raised at 473 K. The tests such as XRD, SEM, EDS, ICP-MS and EA were also determined. The kinetics of WAO over Cu/La/Ce catalyst in oxidation of ammonia solutions using Power-Rate Law was presented to calculate the apparent reaction order and activated energy.

We investigated the reactivity and bonding of perfluoroethyl groups (C2F5) on Cu(111) under ultra high vacuum conditions. Perfluoroethyl moieties bonded to the surface were generated by the dissociative adsorption of perfluoroethyl iodide. Temperature-programmed reaction/desorption (TPR/D) and reflection- adsorption infrared spectroscopy (RAIRS) revealed abounding reaction pathways, and a variety of intermediates were either identified or inferred. The major desorption products, hexafluoro-2-butyne and hexafluorocyclobutene, were detected at 360K and 440K, and some octafluorobutene was observed at 320K at higher coverages, implicating that two fluorine atoms were abstracted step-by-step from the C2F5 on Cu(111). Two sets of signature IR bands were recognized. One set (2054cm-1, 1409cm-1, 1210cm-1) was found to correlate with the surface-bound trifluorovinyl moieties which were also confirmed by directly generating this species from trifluorovinyl iodide. The other set of vibrational features (1322cm-1, 1224cm-1, 950cm-1) presumably implied the trifluoro- ethylidyne intermediate on the surface. Hence, C2F5(ad) underwent the £\-F and £]-F elimination reactions in sequence to yield trifluorovinyl which eventually led to hexafluoro-2-butyne. The alternative route was that C2F5(ad) proceeded via the £\-F elimination reaction twice to render trifluoroethylidyne which ultimately resulted in hexafluorocyclobutene. To our knowledge, the occurrence of the sequential £\-F and£]-F elimination pathway, or the double £\-F elimination reaction has never been observed in any single system.

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Die Cu – Ag - Mikroverbund – Werkstoffe besitzen das Potenzial die gegensätzlichen Anforderungen an das Leitermaterial für den Einsatz in einem Hochfeldmagneten, wie hohe Festigkeit bei gleichzeitig hoher elektrischen Leitfähigkeit und ausreichender Verformbarkeit, zu erfüllen. Außerdem bieten diese Werkstoffe gegenüber den anderen, die dafür in Frage kommen können, den großen technologischen Vorteil einer konventionellen schmelzmetallurgischen Herstellung. Jedoch wurde bisher dafür eine sehr aufwändige Technologie verwendet, die die Herstellung des Leitermaterials nur im Labormaßstab ermöglicht. Die vorliegende Arbeit befasst sich mit einer Technologie der Herstellung von Leitern, die den Anforderungen für den Einsatz in einem Hochfeldmagneten genügen können und in einem großtechnischen Maßstab verfügbar sind. Der Schwerpunkt der Leiterherstellung aus Cu – Ag - Legierung lag in der Einstellung der geeigneten Mikrostruktur über metallkundliche Mechanismen vor der Drahterzeugung. Hierfür wurden während der einzelnen Prozessschritten die Gefügeentwicklung und für die Anwendung relevante Eigenschaften der Legierungen in binären Cu – Ag – Legierungen und in ternären Cu – Ag -X –Legierungen untersucht. Darüber hinaus wurde der Einfluss der Mikrostruktur und der Zusammensetzung auf die mechanischen und elektrischen Eigenschaften der Drähte ermittelt sowie eine Korrelation zwischen Mikrostruktur und elektrischen Eigenschaften aufgestellt.

The electromigration (EM) and chip-package interaction (CPI) reliability of flip chip packages with Cu pillar structures was investigated. First the EM-related characteristics of Cu pillars with solder tips were studied and compared with standard controlled collapse chip connection (C4) Pb-free solder joints. The simulation results revealed a significant reduction in the current crowding effect when C4 solder joints was replaced by Cu pillar structures. As a result, the current-induced Joule heating and local temperature gradients were reduced in the Cu pillar structure. This was followed by a study of the impact of the Cu pillar bumps on the mechanical reliability of low-k dielectrics. The CPI-induced crack driving force for delamination in the low-k interconnect structure was evaluated using a 3D sub-modeling technique. The energy release rate was found to increase significantly for packages with Cu pillar bumps compared with those with C4 Pb-free solder joints only. Structural optimization of Cu pillar bumps to improve the mechanical stability of packages with low-k chips was discussed. / text

Achieving the utmost reliability of power semiconductors is an ongoing challenge for the scientists and engineers in the packaging community of the industry and research institutions. Still the semiconductor and therefore the function of the power module could live longer, when only the bonding and joining technologies would be more stable against power and temperature cycling wearout. In particular, the conventional electrical connection to the top and bottom surface of the semiconductor is limiting the lifetime due to degradation. For both, the solder layer under the backside and the Al-wire on the topside of the die, it is necessary to develop new contact technologies, as the substitution of just one connection does not perform the required reliability of the module. In this work, different new technologies for power modules were evaluated and an own development is presented. Especially the new development is characterized by an outstanding reliability while keeping the design flexibility of the currently applied methods. To achieve that, the solder joints were replaced by Ag-sintered connections and Cu-wires were bonded as a substitute of Al-wires. This new approach is called DBB-Technology („Danfoss BondBuffer“) and is demonstrated in the example of a 1700V DBB power module. With the help of this technology sintering creates two joints: One between the bottom of die and the substrate and between the die and a thin Cu-foil, which is located on top. This Cu foil (BondBuffer) enables the Cu-bond process as top contact technology without damaging the semiconductor. The DBB Cu foil acts as an absorber for the high bond-forces. The detailed characterization of a DBB-covered semiconductor module reveals an extraordinary high reliability improvement, enhanced thermal impedance and upgraded electrical properties. / Leistungsmodule unterliegen in der Anwendung vielfältigen, kombinierten Beanspruchungen, die je nach Anwendung eine Herausforderung an unterschiedliche Verbindungsstellen im Modul darstellen. Die Betriebsdauer eines Leistungsmoduls wird im Wesentlichen von den halbleiternahen Aufbau- und Verbindungstechniken limitiert. Das geht z.B. aus umfangreichen Lastwechseluntersuchungen hervor, in denen als Fehlermechanismen die Zerrüttung des Lots unter dem Chip oder das Abheben des Aluminium-Bonddrahts vom Halbleiter identifiziert wurden. Die einzelnen Verbindungsschichten im Leistungsmodul bilden eine Funktionskette, die beim Ausfall nur eines Gliedes die gesamte Funktionalität verliert. Maßnahmen zur Optimierung einzelner Schichten, z. B. der Halbleiter-Substrat-Verbindung oder nur der oberseitigen Chipkontaktierung, bringen alleinstehend also nicht den gewünschten Erfolg. In dieser Arbeit werden unterschiedliche Aufbaukonzepte leistungselektronischer Module aus Fachveröffentlichungen verglichen, bevor das eigene Konzept beschrieben wird. Die Lösung basiert dabei auf innovativen und sehr robusten Fügetechnologien, die gezielt herkömmliche Verbindungen im Aufbau ersetzen. Das Ergebnis ist ein Leistungsmodul mit verbesserten thermischen, elektrischen und thermo-mechanischen Eigenschaften. Eine wesentliche Rolle spielt dabei das Silbersintern als Alternative zum Löten. Dank der Sintertechnik geht der Halbleiter eine hochfeste Verbindung mit dem Substrat ein. Darüber hinaus ermöglicht die Sintertechnologie das stoffschlüssige Verbinden einer dünnen Kupferfolie mit der oberen Halbleitermetallisierung. Diese Kupferfolie ist erforderlich, um das Cu-Drahtbonden für die oberseitige Kontaktierung der Halbleiter anzuwenden, ohne diesen aufgrund hoher Bondkräfte zu zerstören. Dank der vorteilhaften Materialeigenschaften ist die Cu-Bondverbindung deutlich leistungsfähiger als eine Al-Bondverbindung. Diese Kombination aus robusten Fügestellen trägt den Namen DBB-Technologie („Danfoss BondBuffer“) und soll zukünftig dank der Verfügbarkeit sinterbarer Halbleiter in hochzuverlässigen Leistungsmodulen angewendet werden.

Current methods of solar-grade silicon (SG-Si) production are energy intensive and costly. The possibility of using metallurgical techniques for refining metallurgical-grade Si (MG-Si) to SG-Si has been investigated. The main steps in the metallurgical refining route include alloying with copper to produce a 50-50wt% Cu-Si alloy, controlled solidification, crushing, and acid leaching. The controlled solidification process involved 5 variations to determine the best process to maximize Si dendrite agglomeration in the sample and produce the purest Si. This was determined by using various techniques, such as: optical imaging, dendrite analysis, EPMA and SEM analysis and ICP analysis. The crushing and acid leaching steps were carried out to remove the unwanted Cu3Si eutectic from the pure Si dendrite phase. Upon completion of the analysis techniques, the optimal cooling method was determined to be the top cooled, 0.5°C/min sample.