This master’s thesis deals with design and preparation of a new biodegradable magnesium alloy based on Mg-Ca-Zn. Based on information from literature, the Mg-3Zn-2Ca alloy was designed. The base material was produced by gravity casting and the evaluation in the as-cast and heat treated state was performed. For preparation of the experimental material, following methods were designed: squeeze casting, hot rolling and the ECAP. During preparation by hot rolling, no optimal conditions were found and significant cracks occurred in both as-cast and heat treated material. In the case of experimental material, prepared by the ECAP method with back-pressure, better combination of stress-strain properties was observed. Also the squeeze casting method showed improvement; especially the amount of casting defects was eliminated. The evaluation of microstructure and mechanical properties was performed by the light and scanning electron microscopy, RTG phase analysis and the tensile and compression tests.

Rechargeable aqueous Zn-ion energy storage devices are promising candidates for next-generation energy storage technologies. However, the lack of highly reversible Zn2+-storage anode materials with low potential windows remains a primary concern. Here, we report a two-dimensional polyarylimide covalent organic framework (PI-COF) anode with high-kinetics Zn2+-storage capability. The well-organized pore channels of PI-COF allow the high accessibility of the build-in redox-active carbonyl groups and efficient ion diffusion with a low energy barrier. The constructed PI-COF anode exhibits a specific capacity (332 C g–1 or 92 mAh g–1 at 0.7 A g–1), a high rate capability (79.8% at 7 A g–1), and a long cycle life (85% over 4000 cycles). In situ Raman investigation and first-principle calculations clarify the two-step Zn2+-storage mechanism, in which imide carbonyl groups reversibly form negatively charged enolates. Dendrite-free full Zn-ion devices are fabricated by coupling PI-COF anodes with MnO2 cathodes, delivering excellent energy densities (23.9 ∼ 66.5 Wh kg–1) and supercapacitor-level power densities (133 ∼ 4782 W kg–1). This study demonstrates the feasibility of covalent organic framework as Zn2+-storage anodes and shows a promising prospect for constructing reliable aqueous energy storage devices.

Despite extensive previous studies, the peak metamorphic conditions within the 2.0-1.8 Ga Svecokarelian orogen remain unclear, particularly regarding the deformation and migmatization events occurring between 1.87-1.80 Ga within the Ljusdal lithotectonic unit. While earlier observations indicate granulite facies metamorphism, the exact metamorphic conditions and nature of these events are still unclear. This thesis aims to determine the pressure-temperature range associated with the peak metamorphic conditions by analyzing mineral assemblages in the leucogranite of Sörfjärden, located east of Gnarp, Sweden. Through optical microscopy and electron microprobe analysis, a complex mineral assemblage was identified, including alkali feldspar, plagioclase, garnet, quartz, biotite, sillimanite, and Fe-Zn-rich spinel, with accessory minerals such as monazite, zircon, and rutile. Secondary chlorite and kaolinite were also observed. Ternary-feldspar thermometry revealed crystallization temperatures of 750 ˚C. Thermobarometric modeling of the bulk rock chemical composition, using the software GeoPS, indicated peak pressure-temperature conditions of 2.0–2.4 kbar and 740–770 ˚C, defined by the peak mineral assemblage garnet, plagioclase, quartz, sillimanite, and spinel. Melt structures on biotite and alkali feldspar were inferred to have formed during the second migmatization event, suggesting that granulite facies conditions were reached during the first migmatization event. While these findings provide insights into the metamorphic history of the Svecokarelian orogen, further investigations into the influence of Zn on the produced models are warranted. Addressing the limitations of current thermodynamic models would improve our understanding of this complex geological system. / Trots omfattande tidigare studier är de metamorfa förhållandena i den Svekokarelska orogenesen (2.0–1.8 Ga) fortfarande oklara, särskilt gällande de deformations- och migmatiseringsprocesser som inträffade mellan 1.87–1.80 Ga. Även om tidigare observationer tyder på metamorfos med granulitfacies är de exakta metamorfa förhållandena hos och karaktären av dessa processer fortfarande osäkra. Denna studie syftar till att fastställa det tryck-temperaturintervall som är förknippat med de högsta graderna av metamorfos genom att analysera mineralsammansättningar i leukograniten i Sörfjärden, beläget öster om Gnarp, Sverige. Genom optisk mikroskopi och elektronmikrosonderingsanalys identifierades en komplex mineralsammansättning: alkalifältspat, plagioklas, granat, kvarts, biotit, sillimanit och Fe-Zn-rik spinell, där monazit, zirkon och rutil är accessoriska mineral. Klorit och kaolinit är sekundära. Ternär fältspatstermometri påvisade en kristalliseringstemperatur vid 750 ˚C. Termobarometrisk modellering av bergartens kemiska sammansättning med programmet GeoPS indikerade maximala tryck-temperaturförhållanden på 2.0–2.4 kbar och 740–770 ˚C; mineralsammansättningen under dessa förhållanden var granat, plagioklas, kvarts, sillimanit och spinell. Smältstrukturer på biotit och kalifältspat tolkades ha bildats under den andra migmatiseringen, vilket medför att granulitfacies uppnåddes under den första migmatiseringen. Fastän dessa resultat ger insikter i den Svekokarelska orogenesens metamorfa historia är det motiverat att vidare undersöka inverkan av Zn på de framställda modellerna. Att hantera begränsningarna i nuvarande termodynamiska modeller skulle förbättra vår förståelse av detta komplexa geologiska system.

Alzheimer’s disease (AD), one of the major causes of disability and mortality in Western societies, is a progressive age-related neurodegenerative disorder. Increasing evidence suggests the etiology of AD may involve disruptions of zinc (Zn) homeostasis. We hypothesize that disruption of Zn homeostasis leads to alterations of Zn transporter (ZnT) proteins, resulting in increased production of neurotoxic amyloid beta (Aβ) peptide in AD brain. To address this hypothesis we carried out the following studies. 1. We characterized alterations of ZnT-1, ZnT-4 and ZnT-6 in the brain of preclinical AD (PCAD) subjects, who show no overt clinical manifestations of AD but demonstrate significant AD pathology at autopsy. 2. We identified the presence of ZnT-2 in human brain and compared protein levels in the brains of subjects with PCAD, mild cognitive impairment (MCI), early (EAD), and late-stage AD (LAD) to those in age matched normal control (NC) subjects. 3. We examined the relationship between protein levels of ZnT-1, ZnT-2, ZnT-4, ZnT-6 and Aβ produced by H4 human neuroglioma cells (H4-APP) transfected to overexpress amyloid precursor protein (APP), treated with short interfering RNA (siRNA) against each ZnT. Our data show a significant decrease (P < 0.05) of ZnT-1 and a significant increase of ZnT-6 in hippocampus/parahippo-campal gyrus (HPG) of PCAD subjects. In PCAD cerebellum (CER) the data show a significant increase of ZnT-4 and ZnT-6 compared to NC subjects. Levels of ZnT-2 were also significantly decreased in HPG of PCAD subjects compared to NC subjects. In addition, levels of ZnT-2 were significantly (P < 0.05) elevated in SMTG of PCAD and MCI subjects, compared to NC subjects. ZnT-2 was significantly (P < 0.05) elevated in HPG of EAD and LAD, and in SMTG of LAD brains, but was significantly (P < 0.05) decreased in LAD CER compared to NC subjects. siRNA mediated attenuation of each ZnT protein studied (ZnT-2, ZnT-4 and ZnT-6) led to significantly (P < 0.05) decreased production of Aβ compared to controls. Our results suggest alterations in Zn transport may play a role in Aβ processing and contribute to the neuropathology of AD.

Este trabalho consiste no estudo da eletrodeposição de ligas de Zn/Co para diferentes relações de concentração [Zn2+]/[Co2+] (1:1, 3:1, 6:1, 9:1 e 12:1) sobre aço-carbono ABNT 1020 e sua resistência à corrosão, usando como banho um eletrólito à base de cloretos. Foram realizados estudos preliminares sobre o mecanismo de deposição da liga Zn/Co usando a técnica de voltametria cíclica e estabeleceram-se assim os parâmetros de deposição da liga. Os ensaios de deposição para as relações de concentração [Zn2+]/[Co2+] : 9/1 e [Zn2+]/[Co2+] : 12/1 no banho foram realizados usando a técnica potenciostática (cronoamperometria) e a técnica galvanostática (cronopotenciometria). As relações 1:1, 3:1 e 6:1 não foram escolhidas já que os teores de cobalto de seus eletrodepósitos não estavam na faixa de 1 % a 2 %. Foram feitas análises por microscopia eletrônica de varredura (MEV) para conhecer a diversidade morfologia dos eletrodepósitos como conseqüência do aumento do conteúdo de íons de zinco no banho. A identificação das fases dos eletrodepósitos foi feita por difração de raios X (XRD) e a composição elementar mediante espectroscopia de energia dispersiva de raios X (EDS) e fluorescência de raios X (XRF). Os ensaios de avaliação da resistência à corrosão foram realizados em solução naturalmente areada de NaCl 0,1 M por técnicas eletroquímicas como espectroscopia de impedância eletroquímica e curvas de polarização potenciodinâmicas. A partir dos resultados obtidos na voltametria cíclica foi possível selecionar a faixa de potencial adequada para a realização dos ensaios potenciostáticos e galvanostáticos das relações [Zn2+]/[Co2+] 9:1 e 12:1. As análises dos dados obtidos dos transientes de corrente (ensaios potenciostáticos) para cada relação (9:1 e 12:1) permitiram concluir que para ambas as relações seus processos de nucleação ocorrem seguindo uma transição, iniciando-se como progressiva para t/tmax < 1 e passando a instantânea para t/tmax > 1. As técnicas eletroquímicas usadas para avaliar a resistência à corrosão mostraram que os eletrodepósitos obtidos com a técnica potenciostática foram mais resistentes à corrosão que os eletrodepósitos obtidos com a técnica galvanostática, sendo o potencial de - 1450 mV vs Ag/AgCl e a densidade de corrente catódica de 30 mA/cm2 as melhores condições para a obtenção de eletrodepósitos de Zn/Co com boa resistência à corrosão. / This work reports the study of the electrodeposition of Zn/Co alloys with different concentration ratios [Zn2+]/[Co2+] (1:1, 3:1, 6:1, 9:1 e 12:1) on carbon steel ABNT 1020 and its corrosion resistance, using a chloride - based electrolyte. Initial studies were performed to find the best parameters of deposition by cyclic voltammetry. The alloy deposition for concentration ratios of [Zn2+]/[Co2+] : 9/1 and [Zn2+]/[Co2+] : 12/1 were carried out using potentiostatic (chronoamperometry) and galvanostatic (chronopotenciometry) techniques. The ratios 1:1, 3:1 e 6:1 were not chosen because them composition in cobalt were not within the range of 1% to 2%. Scan electron microscopy (SEM) was performed in order to verify the morphological diversity of the electrodeposits as a consequence of the increasing zinc concentration in the bath. X-ray diffraction was used to identify the phases present in the electrodeposits; their elemental composition was determined by X-ray dispersive energy spectroscopy and X-ray fluorescence. Corrosion resistance experiments were performed in aerated 0,1 M NaCl solution by electrochemical techniques such as electrochemical impedance spectroscopy and potenciodynamic polarization curves. From the voltametric results it was possible to select the adequate potential range in order to perform the potenciostatic and galvanostatic experiments for concentration ratios of [Zn2+]/[Co2+] 9:1 and 12:1. Analysis of the data obtained from the current transients for each ratio (9:1 and 12:1) allow us to conclude that, for both ratios, the processes of nucleation occur following a transition which starts as progressive for t/tmax < 1 and become instantaneous for t/tmax > 1. The electrodeposits obtained by potentiostatic and galvanostatic techniques were evaluated for their corrosion resistant and the best results were found for potentiostatic deposition at -1450 mV vs Ag/AgCl and galvanostatic deposition at 30 mA/cm2. In general, the deposits obtained potentiostatically showed better corrosion resistant.

Submitted by PPG Engenharia e Tecnologia de Materiais (engenharia.pg.materiais@pucrs.br) on 2017-10-10T12:03:59Z No. of bitstreams: 1 Tese_Bernardo_2017_R18_3_Versao_PGETEMA.pdf: 6957919 bytes, checksum: e8811a19bda3fe37ea9ed6f6247594ac (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-10-10T13:43:30Z (GMT) No. of bitstreams: 1 Tese_Bernardo_2017_R18_3_Versao_PGETEMA.pdf: 6957919 bytes, checksum: e8811a19bda3fe37ea9ed6f6247594ac (MD5) / Made available in DSpace on 2017-10-10T13:48:22Z (GMT). No. of bitstreams: 1 Tese_Bernardo_2017_R18_3_Versao_PGETEMA.pdf: 6957919 bytes, checksum: e8811a19bda3fe37ea9ed6f6247594ac (MD5) Previous issue date: 2017-08-31 / CAPES/PROSUP / The objective of the present work is to develop two modified ternary Al-Zn-Mg alloys, with Zn content about 5wt% and 8wt%, and to evaluate the precipitation hardening (solutioning and artificial ageing ? T6) as a function of solidification conditions. The 752 (Al-5%Zn-2%Mg) and 782 (Al-8%Zn-2%Mg) alloys were obtained to analyze the influence of Zn content, as well as the relationship between solidification conditions, precipitation hardening, and mechanical properties before and after heat treatments. Unidirectional vertical upward solidification was performed in a metallic mold cooled by water in the bottom and instrumented using thermocouples to obtain the ingots. Samples extracted from ingots were metallography characterized by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and the mechanical properties were determined by hardness, microhardness, tensile and wear testing. The results showed that the increase of 3% of zinc in the chemical composition improved the hardness of 44%, the superficial wear of 27.7% and the tensile strength of 31.5% (in T6 condition). When comparing the results against data from some similar wrought alloys, it is concluded that the as-cast and heat treated 782 alloy can replace those, according to design specifications. / O objetivo do presente trabalho foi desenvolver duas ligas tern?rias fundidas modificadas de Al-Zn-Mg, com varia??o de 5% e 8% em Zn (em massa), e investigar o endurecimento por precipita??o (solubiliza??o e envelhecimento artificial - T6) em fun??o das condi??es de solidifica??o. Foram produzidas as ligas 752 (Al-5%Zn-2%Mg) e 782 (Al-8%Zn-2%Mg) para analisar, al?m da influ?ncia do teor de zinco, a correla??o entre as condi??es de solidifica??o, o endurecimento por precipita??o e as propriedades mec?nicas iniciais e finais. Para obten??o dos lingotes, a solidifica??o unidirecional vertical ascendente foi realizada em molde met?lico resfriado com ?gua na base e instrumentado com termopares. Amostras foram caracterizadas por an?lises metalogr?ficas em microscopia ?ptica (MO), microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva (EDS), e ensaios mec?nicos para determina??o das propriedades mec?nicas como dureza, microdureza, tra??o e desgaste, antes e ap?s os tratamentos t?rmicos. Os resultados mostraram que o aumento em 3% de zinco na composi??o qu?mica melhorou a dureza em 44,4%, o desgaste superficial em 27,7% e a resist?ncia ? tra??o em 31,5% (em condi??o T6). Comparando estes resultados com dados de algumas ligas conformadas similares, conclui-se que a Liga 782, fundida e tratada termicamente, pode substituir as ligas conformadas comerciais com adi??o de cobre.

As estruturas do tri(hidroximetil) amino metano complexado com cobre Cu(II), Cu[NH2C(COH3)3]2+H2O e do tri(hidroximetil)amino metano dopado com prata Ag(I), Ag[NH2C(COH3)3] foram determinados por difração de raios-x. O complexo contendo íons de cobre refinou até um R de 0.034 e foram encontradas as seguintes características principais: sistema cristalino monoclínico; grupo espacial C2/c, a=12.955(2)&#197; b=10.793(1)&#197; c=10.091(2)&#197; &#946=116.62&#176; V=1261.3(6)&#1973; Z=4; xDc=1.694(2)g/cm-3; &#955(K&#945Mo)=0.71073&#197; das reflexões medidas 1441 tinham I&#62 3&#948 (I). O íon de cobre está coordenado por pares de átomos de oxigênio e nitrogênio os quais formam uma pirâmide de base quadrada, o oxigênio da molécula de água ocupa o outro vértice da pirâmide. A determinação dessa estrutura é utilizada na interpretação da formação de complexos de cobre com tri(hidroximetil) amino metano em função do pH. A estrutura do tri(hidroximetil) amino metano dopado com prata apresentou as seguintes características: sistema cristalino ortorrômbico; grupo espacial Pna21; a=7.800(2)&#197; b=8.810(3)&#197; c=8.850(2)&#197; V=608.85(4)&#1973; Dc=1.329g/cm-3; Dm=1.337g/cm-3; 435 reflexões com I&#62 3&#948 (I); R=0.13; o carbono central é coordenado tetraedricamente por três átomos de carbono do tri(hidroximetil) e um nitrogênio do grupo amino. As estruturas do tris dopado com níquel, e do tris dopado com zinco apresentam-se isomorfa com a estrutura do tris dopado com prata. / The crystal structures of the tri(hydroxymethyl) amine methane complexed with cooper Cu[NH2C(COH3)3]2+H2O and the silver Ag[NH2C(COH3)3] doped into the tri(hydroxymethyl) amine methane have been determined by x-ray diffraction. The complex involving Cu++ refined to final R-factor of 0.034, and the following main features were found: the crystal system is monoclinic and its space group is C2/c, a=12.955(2)&#197; b=10.793(1)&#197; c=10.091(2)&#197; &#946=116.62&#176; V=1261.3(6)&#1973; Z=4; Dc=1.694(2)g/cm-3; &#955(K&#945Mo)=0.71073&#197; from measures done, 1441 had I&#62 3&#948 (I). The Cu++ is coordinated by couples of atoms of oxygen and nytrogen, which form a base of a quadrangular pyramid, the pyramid vertex is formed by the oxygen of the water molecule. The determination of this structure is used to interpret the rise of tri(hydroxymethyl) amine methane and complexed with Cooper varying the pH. The silver doped into the structures of tris(hydroxymethyl) amine methane presented the following features: crystal system is orthorrombic; space group is Pna21; a=7.800(2)&#197; b=8.810(3)&#197; c=8.850(2)&#197; V=608.85(4)&#1973; Dc=1.329 g/cm-3; Dm=1.337 g/cm-3; R=0.13; 435 reflections with I&#62 3&#948 (I) the central carbon is coordinated tetrahedrally by three atoms of carbon from tri(hydroxymethyl) and a nitrogen from the amine group.

P1B-type ATPases transport a number of monovalent and divalent heavy metals (Cu+, Cu2+, Ag+, Zn2+, Cd2+, Pb2+ and Co+2) across biological membranes. These ATPases are found in archea, bacteria and eukaryotes and are one of the key elements required for maintaining metal homeostasis. Plants have an unusually high number of P1B-type ATPases with distinct metal selectivity compared to other eukaryotes that usually have one or two Cu+-ATPases. Higher plants are the only eukaryotes where Zn2+-ATPases have been identified. Towards understanding the physiological roles of plant Zn2+-ATPases, we characterized Arabidopsis thaliana HMA2. We expressed HMA2 in yeast and measured the metal dependent ATPase activity in membranes. We showed that HMA2 is a Zn2+-ATPase that is also activated by Cd2+. Zn2+ transport determinations showed that this enzyme drives the efflux of metal from the cytoplasm. Analysis of HMA2 mRNA levels showed that the enzyme is present in all plant organs. We analyzed the effect of removal of HMA2 full-length transcript in whole plants by gene knock out. Although hma2 mutants did not show a different visible phenotype from the wild type plants, we observed increased levels of Zn2+ or Cd2+. The observed phenotype of hma2 mutants and plasma membrane location of HMA2, mainly in vasculature (Hussain et al., 2004), indicates that this ATPase might have a central role in Zn2+ uploading into the phloem. P1B-type ATPases have cytoplasmic regulatory metal binding domains (MBDs) in addition to transmembrane metal binding sites (TMBDs). Plant Zn2+-ATPases have distinct sequences in both their N- and C-termini that might contribute to novel metal binding sites. These ATPases contain long C-terminal sequences rich in CC dipeptides and His repeats. Removal of the C-terminus (C-MBD) of HMA2 leads to a 50% reduction in the enzyme turnover suggesting a regulatory role for this domain. Atomic Absorption Spectroscopy (AAS) analysis showed that Zn2+ binds to C-MBD with a stoichiometry of three (3 Zn/C-MBD). Chemical modification studies and Zn K-edge X-ray Absorption Spectroscopy (XAS) of Zn-C-MBD showed that Zn2+ is likely coordinated by His in two sites and the third site slightly differs from the others involving a Cys together with three His. All plant Zn2+-ATPases lack the typical CXXC signature sequences observed in Cu+-ATPases and some bacterial Zn2+-ATPases N-terminus metal binding domains (N-MBDs). Instead, these have conserved CCXXE sequences. Truncation of HMA2 N-MBD results in a 50% decrease in enzyme Vmax suggesting that N-MBD is also a regulatory domain. The results indicate that the N-MBD binds Zn2+ with a stoichiometry of one (1 Zn/N-MBD). Metal binding analysis of individual N-MBD mutants Cys17Ala, Cys18Ala and Glu21Ala/Cys prevented Zn+2 binding to HMA2 N-MBD suggesting the involvement of all these residues in metal coordination. ATPase activity measurements with HMA2 carrying the mutations Cys17Ala, Cys18Ala and Glu21Ala/Cys showed a reduction in the enzyme activity similar to that observed the truncated protein indicating that the enzyme activity reduction observed in the N-terminus truncated forms of the enzyme is related to the removal of the metal binding capability. Summaryzing, these studies show the central role of HMA2 in plant Zn2+ homeostasis. They also describe the mechanism and direction of Zn2+ transport. Finally, they establish the presence of novel metal binding domains in the cytoplasmic portion of the enzyme. Metal binding to these domains is required for full enzymatic activity.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-10-03T13:26:39Z No. of bitstreams: 1 Bernardo Bortolotto Ilha_.pdf: 35188571 bytes, checksum: cac488e47b7d5a9301e00e7ab4d1ad4b (MD5) / Made available in DSpace on 2018-10-03T13:26:39Z (GMT). No. of bitstreams: 1 Bernardo Bortolotto Ilha_.pdf: 35188571 bytes, checksum: cac488e47b7d5a9301e00e7ab4d1ad4b (MD5) Previous issue date: 2018-01-16 / UNISINOS - Universidade do Vale do Rio dos Sinos / The aging and electromigration (EM) effects were evaluated when up to 0.19 wt.% Zn was added to Sn-0.7 wt.% Cu solder. Currently, the Sn-0.7 wt.% Cu solder is being widely used in the electronic industries due to its advantages of low cost and high temperature applications. However, its usage is also limited by detrimental properties – for instance, when compared to SAC305, Sn-0.7 wt.% Cu solder has lower electromigration life time, shear strength and drop reliability. Minor Zn alloying to Pb-free solders reportedly enhances some of their properties, e.g.: stabilization of bulk microstructures by decreasing undercooling; formation of a thin interfacial diffusion barrier and, thereby, suppressing Cu3Sn and Cu6Sn5 interfacial IMC growth rate and retarding under bump metallurgy (UBM) diffusion through the solder; and also, compensation for Sn self-diffusion due to reverse polarity effect. In this research, the aging and EM effects are assessed when 0.09, 0.16 and 0.19 wt.% Zn were added to Sn-0.7 wt.% Cu solder. The samples underwent up to 500 h of isothermal aging at temperatures of 125, 150 and 175 °C, and EM samples underwent up to 200 h of stressing at a constant temperature of 150 °C and current of 3.25 A. Solder balls were fabricated on a BGA structure for the aging tests, and for the EM tests, a pair of solders was assembled in a daisy-chain structure with organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG) surface finishes. The microstructural evolution and compositional distribution analyses were carried out using optical microscope with brightfield and cross polarized light, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron probe micro analyzer (EPMA), and electron backscattered diffraction (EBSD). The addition of Zn suppresses the formation of Cu3Sn IMC and the total interfacial IMC thickness upon aging, and the samples with ENIG had smaller IMC thickness than OSP surface finish. In addition, the grains' microstructure becomes less interlaced and more stable, indicating lower undercooling. The electromigration effects on the microstructure is mainly governed by the relative orientation between the c-axis of Sn grains and the direction of current flow. When parallel, allows cathode UBM and alloying elements diffusion through the solder and formation of IMC, and, when transverse, inhibits this diffusion leading to failure by void formation at the anode UBM/solder interface due to depletion of the UBM and slow Sn self-diffusion.

For years, the alloy of choice for electroplating electronic components has been tin-lead (Sn-Pb) alloy. However, the legislation established in Europe on July 1, 2006, required significant lead (Pb) content reductions from electronic hardware due to its toxic nature. A popular alternative for coating electronic components is pure tin (Sn). However, pure tin has the tendency to spontaneously grow electrically conductive Sn whisker during storage. Sn whisker is usually a pure single crystal tin with filament or hair-like structures grown directly from the electroplated surfaces. Sn whisker is highly conductive, and can cause short circuits in electronic components, which is a very significant reliability problem. The damages caused by Sn whisker growth are reported in very critical applications such as aircraft, spacecraft, satellites, and military weapons systems. They are also naturally very strong and are believed to grow from compressive stresses developed in the Sn coating during deposition or over time. The new directive, even though environmentally friendly, has placed all lead-free electronic devices at risk because of whisker growth in pure tin. Additionally, interest has occurred about studying the nature of other metal whiskers such as zinc (Zn) whiskers and comparing their behavior to that of Sn whiskers. Zn whiskers can be found in flooring of data centers which can get inside electronic systems during equipment reorganization and movement and can also cause systems failure.Even though the topic of metal whiskers as reliability failure has been around for several decades to date, there is no successful method that can eliminate their growth. This thesis will give further insights towards the nature and behavior of Sn and Zn whiskers growth, and recommend a novel manufacturing technique that has potential to mitigate metal whiskers growth and extend life of many electronic devices.