The current trend in electronics manufacturing is to decrease the size of electronic components while attempting to increase processing power and performance. This is leading to increased interest in thinner printed wiring boards and finer line widths and wire pitches. However, mismatches in the thermomechanical properties of materials used can lead to warpage, hindering these goals. Warpage can be problematic as it leads to misalignments during package assembly, reduced tolerances, and a variety of operational failures. Current warpage prediction techniques utilize isotropic volume averaging to estimate effective material properties in layers of copper mixed with interlayer dielectric material. However, these estimates do not provide material properties with sufficient accuracy to predict warpage, as they contain no information about the orientation of the copper traces. This thesis describes the development of a new technique to predict the warpage of a particular substrate. The technique accounts for both the trace pattern planar density and planar orientation in determining effective orthotropic material properties for each layer of a multi-layer substrate. Starting with the trace pattern image, this technique first divides the trace pattern into several smaller areas for a given layer of the substrate and then uses image processing techniques to determine the copper percentage and average trace orientation in each small area. The copper percentage and average trace direction orientation are used in conjunction with the material properties of copper and the dielectric material to calculate the effective orthotropic material properties of each smaller area of the substrate. A finite-element model is then created where each layer is represented as a concatenation of several small areas with independent directional properties, and such a model is then subjected to sequential thermal excursion as seen in the actual fabrication process. The results from the models have been compared against experimental data with a great degree of accuracy. The modeling technique and the results obtained clearly demonstrate the need for the proposed subdivisional orthotropic material property calculations, as opposed to homogeneous isotropic properties typically used for each layer in computational simulations, as these more accurate directional properties are capable of predicting warpage with higher accuracy.

This research aims to understand the reliability of Sn-Ag-Cu solder interconnects used in plastic ball grid array (PBGA) packages using microstructure evolution, laser moiré interferometry and finite-element modeling. A particle coarsening based microstructure evolution of the solder joint material during thermal excursions was studied for extended periods of time lasting for several months. The microstructure evolution and particle coarsening was quantified, and acceleration factors were determined between benign field-use conditions and accelerated thermal cycling (ATC) conditions for PBGA packages with different form factors and for two different lead-free solder alloys. A new technique using laser moiré interferometry was developed to assess the deformation behavior of Sn-Ag-Cu based solder joints during thermal excursions. This technique can used to estimate the fatigue life of solder joints quickly in a matter of few days instead of months and can be extended to cover a wide range of temperature regimes. Finite-element analysis (FEA) in conjunction with experimental data from the ATC for different lead-free PBGA packages was used to develop a fatigue life model that can be used to predict solder joint fatigue life for any PBGA package. The proposed model will be able to predict the mean number of cycles required for crack initiation and crack growth rate in a solder joint.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2008. / Includes bibliographical references.

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engfineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009. / Includes bibliographical references.

Nanostrukturen haben in den letzten Jahrzehnten durch konsequente Förderung wie der im Jahr 2000 gestarteten National Nanotechnology Initiative der USA oder des deutschen Pendants Aktionsplan Nanotechnologie erhebliches Aufsehen, nicht nur in der Wissenschaft, sondern auch in der technischen und wirtschaftlichen Umsetzung erfahren. In Kombination mit biologischen Systemen, deren Funktionalität sich auf der Größenordnung von Nanometern abspielt, finden nanotechnologische Entwicklungen auf dem Gebiet der Medizin ein großes technisches Anwendungsgebiet. Diese Arbeit widmet sich der Untersuchung und technischen Entwicklung von Siliziumnanodrähten als Sensoren für zukünftige medizinische Anwendungen. Im Gegensatz zu Sensoren die auf dotierten Nanodrähten basieren, wurden hier undotierte Nanodrähte untersucht, die mit geringerem Produktionsaufwand auskommen und mittels Schottky-Barrieren als Feldeffekttransistoren nutzbar sind. Deren Eigenschaften wurden im Hinblick auf pH und Biosensorik theoretisch und experimentell untersucht, sowie technisch in ein lab-on-chip sowie ein kompaktes Multiplexer-Messgerät integriert. In einem zweiten, separaten Teil wurden die Eigenschaften undotierter Nanodrähte für die optische Spektroskopie theoretisch modelliert. Die Inhalte beider Teile werden im folgenden kurz zusammengefasst. Um die elektrischen Sensoreigenschaften der Siliziumnanodrähte zu untersuchen, wurden zunächst Computermodelle der Drähte erstellt, mit deren Hilfe der Elektronentransport in flüssiger Umgebung quantenmechanisch modelliert wurde. Die dafür erstellten Modellvorstellungen waren für die sich daran anschließenden experimentellen Untersuchungen des Rauschverhaltens, der pH-Sensitivität sowie der Biosensoreigenschaften sehr vorteilhaft. Mit Hilfe einer neu entwickelten Messmethode konnte der optimale Arbeitspunkt der Sensoren ermittelt werden, sowie die hohe Sensorqualität mittels einer empirischen mathematischen Beschreibung des zu erwartenden Sensorsignals eingeordnet werden. Weiterhin wurden für die Medizintechnik relevante Messungen von Thrombin durchgeführt. Damit ist für den hier beschriebenen Sensortyp ein proof-of-concept für neuartige medizinische Messelemente gelungen. Um die kleinen Abmessungen der Sensoren darüber hinaus technisch nutzbar zu machen, wurden sie in ein lab-on-chip System integriert, in welchem sie als Sensoren für den pH-Wert sowie die ionische Konzentration in Nanoliter-Tropfen verwendet wurden. Desweiteren wurde in Kooperation mit dem Institut für Aufbau- und Verbindungstechnik ein portables Messgerät entwickelt, welches die parallele Messung mehrerer Nanodrahtsensoren ermöglicht. Im zweiten Teil der Arbeit wird eine theoretische Untersuchung zur Eignung von Silizium-Nanodrähten als Messsonden (Probes) für die optische Spektroskopie vorgestellt. Dazu wurde eine Methode entwickelt mittels derer es möglich ist, Raman und Infrarotspektren von Nanostrukturen mittels Molekulardynamik zu berechnen. Die Methode wurde auf undotierte Silizium-Nanodrähte augewendet und zeigt, dass die Oberflächenbeschaffenheit der Drähte die optischen Spektren entscheidend beeinflusst. Damit konnte die Relevanz von Halbeiter-Nanostrukturen auch für Anwendungen in der optischen Spektroskopie gezeigt werden. / Nanostructures have attracted great attention not only in scientific research, but also in engineering applications during the last decades. Especially in combination with biological systems, whose complex function is controlled from nanoscale building blocks, nanotechnological developments find a huge field of applications in the medical sector. This work is dedicated to the functional understanding and technical implementation of silicon nanowires for future medical sensor applications. In contrast to doped silicon nanowire based sensors, this work is focussed on pure, undoped silicon nanowires, which have lower demands on production techniques and use Schottky-barriers as electric field detectors. The pH and biosensing capabilities of such undoped silicon nanowire field effect transistors were investigated theoretically and experimentally and further integrated in a lab-on-a-chip device as well as a small-scale multiplexer measurement device. In a second separate part, the optical sensing properties of undoped silicon nanowires were theoretically modeled. The main contents of both parts are shortly described in the following paragraphs. A multiscale model of silicon nanowire FETs to describe the charge transport in liquid surrounding in a quantum mechanical framework was developed to investigate the sensing properties of the nanowire sensors in general. The model set the basis for the understanding of the subsequent experimental investigations of noise characterization, pH sensitivity and biosensing properties. With the help of a novel gate sweeping measurement method the optimal working point of the sensors was determined and the high sensor quality could be quantified in terms of an empirical mathematical model. The sensor was then used for measurements of medically relevant concentrations of the Thrombin protein, providing a proof-of-concept for medical applications for our newly developed sensor. In order to exploit the small size of our sensors for technical applications we integrated the devices in lab-on-a-chip system with a microfluidic droplet generation module. There they were used to measure the pH and ionic concentration of droplets. Finally a portable multiplex measurement device for silicon nanowire sensors as well as other ion sensitive FETs was developed in cooperation with the IAVT at TU Dresden (Institut für Aufbau- und Verbindungstechnik). The second part of this thesis investigates the usability of silicon nanowires for optical sensor applications from a theoretical point of view. Therefore a method for the extraction of Raman and Infrared spectra from molecular dynamics simulations was developed. The method was applied to undoped silicon nanowires and shows that the surface properties of the nanowires has a significant effect on optical spectra. These results demonstrate the relevance of semiconductor nanostructures for applications in optical spectroscopy.

Nanostrukturen haben in den letzten Jahrzehnten durch konsequente Förderung wie der im Jahr 2000 gestarteten National Nanotechnology Initiative der USA oder des deutschen Pendants Aktionsplan Nanotechnologie erhebliches Aufsehen, nicht nur in der Wissenschaft, sondern auch in der technischen und wirtschaftlichen Umsetzung erfahren. In Kombination mit biologischen Systemen, deren Funktionalität sich auf der Größenordnung von Nanometern abspielt, finden nanotechnologische Entwicklungen auf dem Gebiet der Medizin ein großes technisches Anwendungsgebiet. Diese Arbeit widmet sich der Untersuchung und technischen Entwicklung von Siliziumnanodrähten als Sensoren für zukünftige medizinische Anwendungen. Im Gegensatz zu Sensoren die auf dotierten Nanodrähten basieren, wurden hier undotierte Nanodrähte untersucht, die mit geringerem Produktionsaufwand auskommen und mittels Schottky-Barrieren als Feldeffekttransistoren nutzbar sind. Deren Eigenschaften wurden im Hinblick auf pH und Biosensorik theoretisch und experimentell untersucht, sowie technisch in ein lab-on-chip sowie ein kompaktes Multiplexer-Messgerät integriert. In einem zweiten, separaten Teil wurden die Eigenschaften undotierter Nanodrähte für die optische Spektroskopie theoretisch modelliert. Die Inhalte beider Teile werden im folgenden kurz zusammengefasst. Um die elektrischen Sensoreigenschaften der Siliziumnanodrähte zu untersuchen, wurden zunächst Computermodelle der Drähte erstellt, mit deren Hilfe der Elektronentransport in flüssiger Umgebung quantenmechanisch modelliert wurde. Die dafür erstellten Modellvorstellungen waren für die sich daran anschließenden experimentellen Untersuchungen des Rauschverhaltens, der pH-Sensitivität sowie der Biosensoreigenschaften sehr vorteilhaft. Mit Hilfe einer neu entwickelten Messmethode konnte der optimale Arbeitspunkt der Sensoren ermittelt werden, sowie die hohe Sensorqualität mittels einer empirischen mathematischen Beschreibung des zu erwartenden Sensorsignals eingeordnet werden. Weiterhin wurden für die Medizintechnik relevante Messungen von Thrombin durchgeführt. Damit ist für den hier beschriebenen Sensortyp ein proof-of-concept für neuartige medizinische Messelemente gelungen. Um die kleinen Abmessungen der Sensoren darüber hinaus technisch nutzbar zu machen, wurden sie in ein lab-on-chip System integriert, in welchem sie als Sensoren für den pH-Wert sowie die ionische Konzentration in Nanoliter-Tropfen verwendet wurden. Desweiteren wurde in Kooperation mit dem Institut für Aufbau- und Verbindungstechnik ein portables Messgerät entwickelt, welches die parallele Messung mehrerer Nanodrahtsensoren ermöglicht. Im zweiten Teil der Arbeit wird eine theoretische Untersuchung zur Eignung von Silizium-Nanodrähten als Messsonden (Probes) für die optische Spektroskopie vorgestellt. Dazu wurde eine Methode entwickelt mittels derer es möglich ist, Raman und Infrarotspektren von Nanostrukturen mittels Molekulardynamik zu berechnen. Die Methode wurde auf undotierte Silizium-Nanodrähte augewendet und zeigt, dass die Oberflächenbeschaffenheit der Drähte die optischen Spektren entscheidend beeinflusst. Damit konnte die Relevanz von Halbeiter-Nanostrukturen auch für Anwendungen in der optischen Spektroskopie gezeigt werden.:I Introduction: Sensing with Nanostructures 1 Introduction 2 Field effect transistors as electronic sensor elements 3 Packaging: Connecting Nano and Macro 4 Nanostructures as transducers in optical spectroscopy II Electronic sensing with Schottky Barrier silicon nanowires 5 Schottky-Barrier silicon nanowire field effect transistors 6 ISFET measurement principles 7 pH and Biosensing with silicon nanowires 8 Thrombin sensing 9 Silicon nanowire FETs in a Lab-on-a-Chip device 10 Multiplexer sensing platform 11 Experimental methods III Simulating optical spectra of silicon nanowires 12 Theoretical fundamentals 13 Computational Methods 14 Results 15 Bibliography 16 Anhang / Nanostructures have attracted great attention not only in scientific research, but also in engineering applications during the last decades. Especially in combination with biological systems, whose complex function is controlled from nanoscale building blocks, nanotechnological developments find a huge field of applications in the medical sector. This work is dedicated to the functional understanding and technical implementation of silicon nanowires for future medical sensor applications. In contrast to doped silicon nanowire based sensors, this work is focussed on pure, undoped silicon nanowires, which have lower demands on production techniques and use Schottky-barriers as electric field detectors. The pH and biosensing capabilities of such undoped silicon nanowire field effect transistors were investigated theoretically and experimentally and further integrated in a lab-on-a-chip device as well as a small-scale multiplexer measurement device. In a second separate part, the optical sensing properties of undoped silicon nanowires were theoretically modeled. The main contents of both parts are shortly described in the following paragraphs. A multiscale model of silicon nanowire FETs to describe the charge transport in liquid surrounding in a quantum mechanical framework was developed to investigate the sensing properties of the nanowire sensors in general. The model set the basis for the understanding of the subsequent experimental investigations of noise characterization, pH sensitivity and biosensing properties. With the help of a novel gate sweeping measurement method the optimal working point of the sensors was determined and the high sensor quality could be quantified in terms of an empirical mathematical model. The sensor was then used for measurements of medically relevant concentrations of the Thrombin protein, providing a proof-of-concept for medical applications for our newly developed sensor. In order to exploit the small size of our sensors for technical applications we integrated the devices in lab-on-a-chip system with a microfluidic droplet generation module. There they were used to measure the pH and ionic concentration of droplets. Finally a portable multiplex measurement device for silicon nanowire sensors as well as other ion sensitive FETs was developed in cooperation with the IAVT at TU Dresden (Institut für Aufbau- und Verbindungstechnik). The second part of this thesis investigates the usability of silicon nanowires for optical sensor applications from a theoretical point of view. Therefore a method for the extraction of Raman and Infrared spectra from molecular dynamics simulations was developed. The method was applied to undoped silicon nanowires and shows that the surface properties of the nanowires has a significant effect on optical spectra. These results demonstrate the relevance of semiconductor nanostructures for applications in optical spectroscopy.:I Introduction: Sensing with Nanostructures 1 Introduction 2 Field effect transistors as electronic sensor elements 3 Packaging: Connecting Nano and Macro 4 Nanostructures as transducers in optical spectroscopy II Electronic sensing with Schottky Barrier silicon nanowires 5 Schottky-Barrier silicon nanowire field effect transistors 6 ISFET measurement principles 7 pH and Biosensing with silicon nanowires 8 Thrombin sensing 9 Silicon nanowire FETs in a Lab-on-a-Chip device 10 Multiplexer sensing platform 11 Experimental methods III Simulating optical spectra of silicon nanowires 12 Theoretical fundamentals 13 Computational Methods 14 Results 15 Bibliography 16 Anhang

Conventional microelectronic and power electronic packages based on Si devices usually work below 150°C. The emergence of wide-bandgap devices, which potentially operate above a junction temperature of 250°C, results in growing research interest in high-density and high-temperature packaging. There are high-temperature materials such as encapsulants on the market that are claimed for capability of continuous operation at or above 250°C. With an objective of identifying encapsulants suitable for packaging wide-bandgap devices, some of commercial high-temperature encapsulants were obtained and evaluated at the beginning of this study. The evaluation revealed that silicone elastomers are processable for various types of package structure and exhibit excellent dielectric performance in a wide temperature range (25 - 250°C) but are insufficiently stable against long-term aging (used by some manufacturers, e.g., P²SI, to evaluate polymer stability) at 250°C. These materials cracked during aging, causing their dielectric strength to decrease quickly (as soon as 3 days) and significantly (60 - 70%) to approximately 5 kV/mm, which is below the value required by semiconductor packaging. The results of this evaluation clearly suggested that silicone needs higher thermal stability to reliably encapsulate wide-bandgap devices. Literature survey then investigated possible methods to improve silicone stability. Adding fillers is reported to be effective possibly due to the interaction between filler surface and polymer chains. However, the interaction mechanism is not clearly documented. In this study, the effect of Al₂O₃ filler on thermal stability was first investigated by comparing the performance of unfilled and Al₂O₃-filled silicones in weight-loss measurements and dielectric characterization. All test results on composites filed with Al₂O₃ micro-rods indicated that thermal stability increased with increasing filler loading. Thermogravimetric analysis (TGA) test demonstrated that the temperature of degradation onset increased from 330 to 379°C with a 30 wt% loading of Al₂O₃ rods. In isothermal soak test, unfilled and 30-wt%-filled silicones lost 10% of polymer weight in 700 and 1800 hours, respectively. The dielectric characterization found that both Weibull parameters, characteristic dielectric strength (E₀, representing the electric field at which 62.3% of samples are electrically broken down) and shape parameter (β, representing the spread of data. The larger the β, the narrower the distribution) can reflect the thermal stability of polymers. Both of them were influenced by microstructure evolution, to which β was found to be more sensitive than E₀. The characteristic dielectric strength of unfilled silicone decreased significantly after 240 hours of aging at 250°C, whereas that of Al₂O₃/silicone composites exhibited no significant change within 560 hours. The shape parameter of Al₂O₃-filled silicone decreased slower than that of unfilled silicone, also indicating the positive effect of Al₂O₃ micro-rods on thermal stability. Improved thermal stability can be explained by restrained chain mobility caused by interfacial hydrogen bonds, which are formed between hydroxyl groups on Al₂O₃ surface and silicone backbone. In this study, the effect of hydrogen bonds was investigated by dehydrating Al₂O₃ micro-rods at high temperature in N₂ to partially destroy the bonds. Removal of hydrogen bonds impaired thermal stability by increasing the initial weight-loss rate from 0.025 to 0.036 wt%/hour. The results explained the importance of interfacial hydrogen bond, which effectively reduced the average chain mobility, hindered the formation of degradation products, and led to higher thermal stability. The main discoveries of this study are listed below: 1. Al₂O₃ micro-rods were found to efficiently improve the thermal stability of silicone elastomer used for high-temperature encapsulation. 2. Characteristic dielectric strength and shape parameter obtained from Weibull distribution reflected the change of material microstructure caused by thermal aging. The shape parameter was found to be more sensitive to microscale defects, which were responsible for dielectric breakdown at low electric field. 3. Hydrogen bonds existing at filler/matrix interface were proven to be responsible for the improvement of thermal stability because they effectively restrained the average chain mobility of the silicone matrix. / Ph. D.

Electronic Packaging is currently deeply in need of new solutions concerning vertical interconnection strategies. With respect to downscaling the geometrical limits, entering the nanoscale for first-level interconnects is nothing more than a consequence. This thesis proposes a new strategy for highly resolved vertical interconnects that are realized by metallic nanowires (NWs). These are embedded inside a dielectric matrix enabling the further raster size reduction for chip interconnects. The creation of NW arrays in self-ordering templates (anodized Al2O3 (AAO) and track-etched poly carbonate) by electrochemical deposition of Ag and Ni inside the pores of these as well as the characterisation of the NWs' properties with respect to the film's applicability are to the fore. Electrical properties are shown to be sensitive to the mode of deposition. Crystallographic properties do not seem to be responsible for this while the NWs' morphology slightly differs and is therefore expected to remarkably influence electron transport. Additionally, the deposition mechanism in high-aspect-ratio pores of AAO is in another focus of investigation. This process was in the past described as diffusively controlled, but this assertion was not further evaluated. The presence of a gradient in the diffusion coefficient as well as the presence and expansion of an electrochemical double layer located at the template's inner surface are responsible limiting the deposition process. An existing model of porous electrodes is compared to the measured data and found not to be valid for the system of highly recessed ultramicroelectrode arrays by which this system is described. Therefore a new model that differentiates between charge-transfer and diffusive motion is proposed and shown to fit to the system's properties. Apart from mechanistic investigations, the implementation of the obtained NW arrays as an interconnector film proposes these to be applied best by adhesive bonding. Bonding properties were found to be well realizable by the additional coverage of the filled membranes with a polymer thin film. This can easily be attached onto the film by spin-coating the corresponding monomer and reactive curing while already being embedded in the package. Alternative methods for contact formation, such as non-reactive bonding and nanosoldering using segmented NWs, are proposed. The strategy is shown to still lack important technological questions while the findings with respect to fabrication, growth and implementation are very promising. / Die Aufbau- und Verbindungstechnik der Elektronik wird in absehbarer Zeit Größenskalen erreichen, bei denen die verwendeten Materialien in der ersten Kontaktierungsebene als Nanomaterialien zu bezeichnen sind, das heißt ≤ 100 nm sind. Des Weiteren bestehen momentan nur bedingt viele Ansätze zu deren Implementierung in Vertikalverbindungsstrukturen (zum Beispiel für die dreidimensionale Integration). Die vorliegende Dissertation schlägt daher vor, die vertikale Verbindung über einen zwischen die Chips laminierbaren Film mit hochdichten und vertikal ausgerichteten nanoskaligen Drähten (NWs) zu realisieren. Diese sind in einer dielektrischen Matrix fixiert und gewährleisten die elektrische Anisotropie des Kontaktfilms. Innerhalb dieser Matrix werden die metallischen Drähte durch elektrochemische Abscheidung erzeugt. Der Fokus dieser Arbeit liegt somit auf der Charakterisierung des reduktiven Wachstumsprozesses von Ag und Ni innerhalb dünner Poren. Dabei können die Eigenschaften durch verschiedene Abscheidemodi gezielt beeinflusst werden. Hinsichtlich der elektrischen Eigenschaften ergibt sich im Vergleich zu der zugrundeliegenden Kristallographie ein wesentlich stärkerer Einfluss der Draht-Morphologie. Der Prozess der Porenfüllung wird im Allgemeinen als stark diffusionskontrolliert angenommen, wurde jedoch bisher nicht weiter quantifiziert. Die der Abscheidung zugrundeliegenden Prozesse Elektrolytdiffusion, Ladungstransfer an der Elektrode und Migrationsbeeinflussung durch die Porengeometrie werden daher voneinander getrennt und einzeln charakterisiert. Das vorliegende System kann als Matrix von stark versenkten Ultramikroelektroden abstrahiert werden. Existente Modelle zur Beschreibung derartiger Systeme treffen auf den vorliegenden Fall im Allgemeinen nicht zu, sodass basierend auf elektrochemischen Untersuchungen ein variiertes Abscheidemodell vorgeschlagen wird. Dieses berücksichtigt die Nicht-Linearität der elektrochemischen Doppelschicht, die von der Porenoberfläche ausgeht sowie deren Frequenzabhängigkeit. Neben mechanistischen Untersuchungen schließen sich Versuche an, deren Fokus auf der direkten Anwendung der mit Nanodrähten gefüllten Membranen liegt. Dabei wird vornehmlich deren Fixierung per Klebeverbindung angestrebt. Die Realisierung klebbarer Filme gelingt über die Auftragung von polymeren Dünnfilmen durch Spin-Coating des jeweiligen Monomeren. Diese Filme werden hinsichtlich ihrer Klebeeigenschaften charakterisiert. Abschließend werden alternative Kontaktiermethoden wie die Thermokompression oder das nanoskalige Löten basierend auf der Herstellung von segmentierten Nanodrähten demonstriert und hinsichtlich ihrer Applizierbarkeit diskutiert. Die erreichten Ergebnisse zeigen den noch vorhandenen Bedarf an technologischer Optimierung sowie Kompatibilisierung auf. Die Erkenntnisse hinsichtlich der Herstellung, des Wachstums sowie der Implementierungsansätze sind jedoch vielversprechend.

Sn-Pb solder has long been used in the Electronics industry. But, due to its toxic nature and environmental effects, certain restrictions are made on its use and therefore many researchers are looking to replace it. Sn-3.0Ag-0.5Cu (SAC) solders are suggested as lead-free replacements but their coarse microstructure and formation of hard and brittle Inter-Metallic Compounds (IMCs) like Ag₃Sn and Cu₆Sn₅ have limited their use in high temperature applications. In this research work, RE elements, mostly lanthanum (La), are used as potential additives to SAC alloys. They reduce the surface free energy, refine the grain size and improve the mechanical and wetting properties of SAC alloys. An extensive experimental work has been performed on the microstructure evolution, bulk mechanical properties, individual phase (matrix and IMCs) mechanical properties, creep behavior and wettability performance of the SAC and SAC-La alloys, with different (La) doping. SEM and EDS have been used to follow the continuous growth of the IMCs at 150°C and 200°C and thus provide a quantitative measure in terms of their size, spacing and volume fraction. Grain size is measured at regular intervals starting from 10 hours up to 200 hours of thermal aging using Optical Microscope with cross polarized light. Bulk mechanical properties are evaluated using tensile tests at low strain rates. Individual phase mechanical properties like Young's modulus, hardness, strain rate sensitivity index and bulge effects are characterized with nanoindentation from 100 µN up to 5000 µN loadings at different temperatures of 25°C, 45°C, 65°C and 85°C. Creep experiments are performed at elevated temperatures with good fitting of Dorn creep and back-stress creep models. Activation energy measurements are made at 40°C, 80°C and 120°C. Wettability testing on copper substrates is used for surface tension, wetting force and contact angle measurements of SAC and SAC-La doped alloys at 250°C and 260°C.

Electronic Packaging is currently deeply in need of new solutions concerning vertical interconnection strategies. With respect to downscaling the geometrical limits, entering the nanoscale for first-level interconnects is nothing more than a consequence. This thesis proposes a new strategy for highly resolved vertical interconnects that are realized by metallic nanowires (NWs). These are embedded inside a dielectric matrix enabling the further raster size reduction for chip interconnects. The creation of NW arrays in self-ordering templates (anodized Al2O3 (AAO) and track-etched poly carbonate) by electrochemical deposition of Ag and Ni inside the pores of these as well as the characterisation of the NWs' properties with respect to the film's applicability are to the fore. Electrical properties are shown to be sensitive to the mode of deposition. Crystallographic properties do not seem to be responsible for this while the NWs' morphology slightly differs and is therefore expected to remarkably influence electron transport. Additionally, the deposition mechanism in high-aspect-ratio pores of AAO is in another focus of investigation. This process was in the past described as diffusively controlled, but this assertion was not further evaluated. The presence of a gradient in the diffusion coefficient as well as the presence and expansion of an electrochemical double layer located at the template's inner surface are responsible limiting the deposition process. An existing model of porous electrodes is compared to the measured data and found not to be valid for the system of highly recessed ultramicroelectrode arrays by which this system is described. Therefore a new model that differentiates between charge-transfer and diffusive motion is proposed and shown to fit to the system's properties. Apart from mechanistic investigations, the implementation of the obtained NW arrays as an interconnector film proposes these to be applied best by adhesive bonding. Bonding properties were found to be well realizable by the additional coverage of the filled membranes with a polymer thin film. This can easily be attached onto the film by spin-coating the corresponding monomer and reactive curing while already being embedded in the package. Alternative methods for contact formation, such as non-reactive bonding and nanosoldering using segmented NWs, are proposed. The strategy is shown to still lack important technological questions while the findings with respect to fabrication, growth and implementation are very promising.:List of Figures List of Tables List of Acronyms List of Symbols 1 Nanoscale interconnects 1 1.1 Introduction 1.2 Electronic device development and its consequences 1.3 The need for and the design of a nanoscale wiring film 1.3.1 Nanomaterials for packaging - Some examples 1.3.2 Preconsiderations for designing nanoscale interconnects 1.3.3 Compatitibility of ACANWF to industrial applications 1.3.4 Demands to the film 1.4 Resumée - Strategy 2 NW fabrication by electodeposition and synthesis-property relationships 2.1 Templates for NW electrodeposition 2.1.1 Anodized Al2O3 (AAO) 2.1.2 Track-etched polymer membranes 2.2 Template-assisted Electrochemical Deposition (ECD) of NWs 2.2.1 Concept 2.2.2 Deposition modes 2.2.3 In_uences of other physical parameters 2.2.4 Errors and error mechanisms 2.2.5 Deposition in chemically functionalized AAO 2.3 Synthesis-property relationships for single NWs 2.3.1 NiNWs 2.3.2 AgNWs 2.4 Resumée . 3 Growth processes in mesoporous templates 3.1 Relevance for mechanistic investigations 3.2 Processes during NW growth 3.2.1 Electrode kinetics 3.2.2 Diffusion 3.2.3 Interactions with pore walls 3.3 Model systems 3.3.1 DeLevie's model for porous electrodes 3.3.2 Model verification 3.3.3 Model adaptation to non-ideal behaviour 3.4 Resumée 4 Implementation of nanowire arrays into microelectronic packaging 4.1 Adhesive Bonding 4.1.1 Adhesion by thin adhesive layers 4.1.2 Thermocompression bonds 4.2 Nanosoldering 4.2.1 Deposition of low melting point materials 4.2.2 Segmented nanowires 4.3 Resumée 5 Conclusion and perspectives 5.1 Conclusion 5.2 Perspectives on further investigations 6 Appendices 6.1 Technical equipment 6.2 Experimental methods 6.3 Selected characterisation techniques 6.4 Supplementary Information 6.5 Glossary 6.6 List of publications & presentations Bibliography / Die Aufbau- und Verbindungstechnik der Elektronik wird in absehbarer Zeit Größenskalen erreichen, bei denen die verwendeten Materialien in der ersten Kontaktierungsebene als Nanomaterialien zu bezeichnen sind, das heißt ≤ 100 nm sind. Des Weiteren bestehen momentan nur bedingt viele Ansätze zu deren Implementierung in Vertikalverbindungsstrukturen (zum Beispiel für die dreidimensionale Integration). Die vorliegende Dissertation schlägt daher vor, die vertikale Verbindung über einen zwischen die Chips laminierbaren Film mit hochdichten und vertikal ausgerichteten nanoskaligen Drähten (NWs) zu realisieren. Diese sind in einer dielektrischen Matrix fixiert und gewährleisten die elektrische Anisotropie des Kontaktfilms. Innerhalb dieser Matrix werden die metallischen Drähte durch elektrochemische Abscheidung erzeugt. Der Fokus dieser Arbeit liegt somit auf der Charakterisierung des reduktiven Wachstumsprozesses von Ag und Ni innerhalb dünner Poren. Dabei können die Eigenschaften durch verschiedene Abscheidemodi gezielt beeinflusst werden. Hinsichtlich der elektrischen Eigenschaften ergibt sich im Vergleich zu der zugrundeliegenden Kristallographie ein wesentlich stärkerer Einfluss der Draht-Morphologie. Der Prozess der Porenfüllung wird im Allgemeinen als stark diffusionskontrolliert angenommen, wurde jedoch bisher nicht weiter quantifiziert. Die der Abscheidung zugrundeliegenden Prozesse Elektrolytdiffusion, Ladungstransfer an der Elektrode und Migrationsbeeinflussung durch die Porengeometrie werden daher voneinander getrennt und einzeln charakterisiert. Das vorliegende System kann als Matrix von stark versenkten Ultramikroelektroden abstrahiert werden. Existente Modelle zur Beschreibung derartiger Systeme treffen auf den vorliegenden Fall im Allgemeinen nicht zu, sodass basierend auf elektrochemischen Untersuchungen ein variiertes Abscheidemodell vorgeschlagen wird. Dieses berücksichtigt die Nicht-Linearität der elektrochemischen Doppelschicht, die von der Porenoberfläche ausgeht sowie deren Frequenzabhängigkeit. Neben mechanistischen Untersuchungen schließen sich Versuche an, deren Fokus auf der direkten Anwendung der mit Nanodrähten gefüllten Membranen liegt. Dabei wird vornehmlich deren Fixierung per Klebeverbindung angestrebt. Die Realisierung klebbarer Filme gelingt über die Auftragung von polymeren Dünnfilmen durch Spin-Coating des jeweiligen Monomeren. Diese Filme werden hinsichtlich ihrer Klebeeigenschaften charakterisiert. Abschließend werden alternative Kontaktiermethoden wie die Thermokompression oder das nanoskalige Löten basierend auf der Herstellung von segmentierten Nanodrähten demonstriert und hinsichtlich ihrer Applizierbarkeit diskutiert. Die erreichten Ergebnisse zeigen den noch vorhandenen Bedarf an technologischer Optimierung sowie Kompatibilisierung auf. Die Erkenntnisse hinsichtlich der Herstellung, des Wachstums sowie der Implementierungsansätze sind jedoch vielversprechend.:List of Figures List of Tables List of Acronyms List of Symbols 1 Nanoscale interconnects 1 1.1 Introduction 1.2 Electronic device development and its consequences 1.3 The need for and the design of a nanoscale wiring film 1.3.1 Nanomaterials for packaging - Some examples 1.3.2 Preconsiderations for designing nanoscale interconnects 1.3.3 Compatitibility of ACANWF to industrial applications 1.3.4 Demands to the film 1.4 Resumée - Strategy 2 NW fabrication by electodeposition and synthesis-property relationships 2.1 Templates for NW electrodeposition 2.1.1 Anodized Al2O3 (AAO) 2.1.2 Track-etched polymer membranes 2.2 Template-assisted Electrochemical Deposition (ECD) of NWs 2.2.1 Concept 2.2.2 Deposition modes 2.2.3 In_uences of other physical parameters 2.2.4 Errors and error mechanisms 2.2.5 Deposition in chemically functionalized AAO 2.3 Synthesis-property relationships for single NWs 2.3.1 NiNWs 2.3.2 AgNWs 2.4 Resumée . 3 Growth processes in mesoporous templates 3.1 Relevance for mechanistic investigations 3.2 Processes during NW growth 3.2.1 Electrode kinetics 3.2.2 Diffusion 3.2.3 Interactions with pore walls 3.3 Model systems 3.3.1 DeLevie's model for porous electrodes 3.3.2 Model verification 3.3.3 Model adaptation to non-ideal behaviour 3.4 Resumée 4 Implementation of nanowire arrays into microelectronic packaging 4.1 Adhesive Bonding 4.1.1 Adhesion by thin adhesive layers 4.1.2 Thermocompression bonds 4.2 Nanosoldering 4.2.1 Deposition of low melting point materials 4.2.2 Segmented nanowires 4.3 Resumée 5 Conclusion and perspectives 5.1 Conclusion 5.2 Perspectives on further investigations 6 Appendices 6.1 Technical equipment 6.2 Experimental methods 6.3 Selected characterisation techniques 6.4 Supplementary Information 6.5 Glossary 6.6 List of publications & presentations Bibliography