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Description
Pb-free solders are used as interconnects in various levels of micro-electronic packaging. Reliability of these interconnects is very critical for the performance of the package. One of the main factors affecting the reliability of solder joints is the presence of porosity which is introduced during processing of the joints. In

Pb-free solders are used as interconnects in various levels of micro-electronic packaging. Reliability of these interconnects is very critical for the performance of the package. One of the main factors affecting the reliability of solder joints is the presence of porosity which is introduced during processing of the joints. In this thesis, the effect of such porosity on the deformation behavior and eventual failure of the joints is studied using Finite Element (FE) modeling technique. A 3D model obtained by reconstruction of x-ray tomographic image data is used as input for FE analysis to simulate shear deformation and eventual failure of the joint using ductile damage model. The modeling was done in ABAQUS (v 6.10). The FE model predictions are validated with experimental results by comparing the deformation of the pores and the crack path as predicted by the model with the experimentally observed deformation and failure pattern. To understand the influence of size, shape, and distribution of pores on the mechanical behavior of the joint four different solder joints with varying degrees of porosity are modeled using the validated FE model. The validation technique mentioned above enables comparison of the simulated and actual deformation only. A more robust way of validating the FE model would be to compare the strain distribution in the joint as predicted by the model and as observed experimentally. In this study, to enable visualization of the experimental strain for the 3D microstructure obtained from tomography, a three dimensional digital image correlation (3D DIC) code has been implemented in MATLAB (MathWorks Inc). This developed 3D DIC code can be used as another tool to verify the numerical model predictions. The capability of the developed code in measuring local displacement and strain is demonstrated by considering a test case.
ContributorsJakkali, Vaidehi (Author) / Chawla, Nikhilesh K (Thesis advisor) / Jiang, Hanqing (Committee member) / Solanki, Kiran (Committee member) / Arizona State University (Publisher)
Created2011
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Description

Waste pickers are the victims of harsh economic and social factors that have hurt many developing countries and billions of people around the world. Due to the rise of industrialization since the 19th century, waste and disposable resources have been discarded around the world to provide more resources, products, and

Waste pickers are the victims of harsh economic and social factors that have hurt many developing countries and billions of people around the world. Due to the rise of industrialization since the 19th century, waste and disposable resources have been discarded around the world to provide more resources, products, and services to wealthy countries. This has put developing countries in a precarious position where people have had very few economic opportunities besides taking on the role of waste pickers, who not only face physical health consequences due to the work they do but also face exclusion from society due to the negative views of waste pickers. Many people view waste pickers as scavengers and people who survive off of doing dirty work, which creates tensions between waste pickers and others in society. This even leads to many countries outlawing waste picking and has led to the brutal treatment of waste pickers throughout the world and has even led to thousands of waste pickers being killed by anti-waste picker groups and law enforcement organizations in many countries. <br/> Waste pickers are often at the bottom of supply-chains as they take resources that have been used and discarded, and provide them to recyclers, waste management organizations, and others who are able to turn these resources into usable materials again. Waste pickers do not have many opportunities to rise above the situation they are in as waste picking has become the only option for many people who need to provide for themselves and their families. They are not compensated very well for the work they do, which also contributes to the situation where waste pickers are forced into a position of severe health risks, backlash from society and governments, not being able to seek better opportunities due to a lack of earning potential, and not being connected with end-users. Now is the time to create new business models that solve these large problems in our global society and create a sustainable way to ensure that waste pickers are treated properly around the world.

ContributorsKidd, Isabella Joy (Co-author) / Kapps, Jack (Co-author) / Urbina-Bernal, Alejandro (Thesis director) / Byrne, Jared (Committee member) / Marseille, Alicia (Committee member) / Jordan, Amanda (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Morrison School of Agribusiness (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Department of Finance (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

In the current age of global climate crisis, corporations must confront the rising pressure to mitigate their environmental impacts. The goal of this research paper is to provide corporations with a resource to manage waste through the implementation of a circular economy and by increasing Corporate Social Responsibility (CSR). Navigating

In the current age of global climate crisis, corporations must confront the rising pressure to mitigate their environmental impacts. The goal of this research paper is to provide corporations with a resource to manage waste through the implementation of a circular economy and by increasing Corporate Social Responsibility (CSR). Navigating this large and complex system required the use of various methodologies including: the investigation of the relationships between waste management systems and sustainable development across major companies; literature reviews of scholarly articles about CSR, circular economies, recycling, and releases of company reports on sustainable development and financials. Lastly, interviews and a survey were conducted to gain deeper insight into the problems that make circular economies so difficult to achieve at scale.

ContributorsBird, Alex William (Author) / Heller, Cheryl (Thesis director) / Trujillo, Rhett (Committee member) / Department of Finance (Contributor) / Department of Management and Entrepreneurship (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description

The process of producing enormous amounts of ephemeral clothing at accelerated rates, known as fast fashion, creates significant environmental and societal issues. The phenomenon of fast fashion rose due to globalization, economic factors, lack of legislation, and the advancement of technology. Governments, companies, and consumers must work together to create

The process of producing enormous amounts of ephemeral clothing at accelerated rates, known as fast fashion, creates significant environmental and societal issues. The phenomenon of fast fashion rose due to globalization, economic factors, lack of legislation, and the advancement of technology. Governments, companies, and consumers must work together to create more sustainable retail supply chains. I have gathered information from interviews with individuals in the sustainable fashion industry, books, case studies, online reports, and newspaper articles. Based on my research, I recommend that companies should target wealthier consumers, develop a common language concerning sustainability, invest in sustainable fibers, and listen to factory employees for solutions to improve their working conditions. I also advise that the U.S governments should revise fashion copyright laws and international governments should emphasize regulations concerning the fashion industry. Lastly, consumers should adopt a price-per-wear mindset and utilize resale options. Overall, while perfect sustainability is improbable, consumers, governments, and companies should not use this as an excuse to avoid responsibility.

ContributorsWillner, Allison (Author) / Koretz, Lora (Thesis director) / Moore, James (Committee member) / Department of Management and Entrepreneurship (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

Brundtland’s definition of sustainability is the ability to “meet the needs of the present<br/>without compromising the ability of future generations to meet their needs” (IISD, 2021). But<br/>what if there are no future generations? Social sustainability, the sector of sustainability that<br/>foregrounds the well-being and livelihoods of people (and thereby continuation of

Brundtland’s definition of sustainability is the ability to “meet the needs of the present<br/>without compromising the ability of future generations to meet their needs” (IISD, 2021). But<br/>what if there are no future generations? Social sustainability, the sector of sustainability that<br/>foregrounds the well-being and livelihoods of people (and thereby continuation of humanity), is<br/>included in definitions within the sustainability field, but less developed in sustainability<br/>practice. In an effort to bridge this gap of knowledge, 14 U.S. cities and over 100 sustainability<br/>policies were analyzed for their social sustainability performance. An eight-item analytical<br/>framework that deals with differing areas of social equity guided the analysis. Results found that<br/>most cities’ sustainability departments fell short of truly addressing social sustainability<br/>concerns. Out of the eight items, the most frequently addressed were housing security and racial<br/>and gender equality whereas few, if any, cities addressed the more specific social concerns of<br/>immigration, technology and media, or arts/cultural preservation. Future research is<br/>recommended to gain a better understanding of the ways existing cities can improve in this area.

ContributorsWeekes, Daniel Buckner (Co-author) / Tam, Joey (Co-author) / Brian, Jennifer (Thesis director) / Keeler, Lauren Withycombe (Thesis director) / N/A, N/A (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Department of Economics (Contributor) / Department of Supply Chain Management (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

This thesis project has been conducted in accordance with The Founder’s Lab initiative which is sponsored by the W. P. Carey School of Business. This program groups three students together and tasks them with creating a business idea, conducting the necessary research to bring the concept to life, and exploring

This thesis project has been conducted in accordance with The Founder’s Lab initiative which is sponsored by the W. P. Carey School of Business. This program groups three students together and tasks them with creating a business idea, conducting the necessary research to bring the concept to life, and exploring different aspects of business, with the end goal of gaining traction. The product we were given to work through this process with was Hot Head, an engineering capstone project concept. The Hot Head product is a sustainable and innovative solution to the water waste issue we find is very prominent in the United States. In order to bring the Hot Head idea to life, we were tasked with doing research on topics ranging from the Hot Head life cycle to finding plausible personas who may have an interest in the Hot Head product. This paper outlines the journey to gaining traction via a marketing campaign and exposure of our brand on several platforms, with a specific interest in website traffic. Our research scope comes from mainly primary sources like gathering opinions of potential buyers by sending out surveys and hosting focus groups. The paper concludes with some possible future steps that could be taken if this project were to be continued.

ContributorsGoodall, Melody Anne (Co-author) / Rote, Jennifer (Co-author) / Lozano Porras, Mariela (Co-author) / Byrne, Jared (Thesis director) / Sebold, Brent (Committee member) / Department of Finance (Contributor) / Department of Economics (Contributor) / Dean, W.P. Carey School of Business (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description
Recently, the use of zinc oxide (ZnO) nanowires as an interphase in composite materials has been demonstrated to increase the interfacial shear strength between carbon fiber and an epoxy matrix. In this research work, the strong adhesion between ZnO and carbon fiber is investigated to elucidate the interactions at the

Recently, the use of zinc oxide (ZnO) nanowires as an interphase in composite materials has been demonstrated to increase the interfacial shear strength between carbon fiber and an epoxy matrix. In this research work, the strong adhesion between ZnO and carbon fiber is investigated to elucidate the interactions at the interface that result in high interfacial strength. First, molecular dynamics (MD) simulations are performed to calculate the adhesive energy between bare carbon and ZnO. Since the carbon fiber surface has oxygen functional groups, these were modeled and MD simulations showed the preference of ketones to strongly interact with ZnO, however, this was not observed in the case of hydroxyls and carboxylic acid. It was also found that the ketone molecules ability to change orientation facilitated the interactions with the ZnO surface. Experimentally, the atomic force microscope (AFM) was used to measure the adhesive energy between ZnO and carbon through a liftoff test by employing highly oriented pyrolytic graphite (HOPG) substrate and a ZnO covered AFM tip. Oxygen functionalization of the HOPG surface shows the increase of adhesive energy. Additionally, the surface of ZnO was modified to hold a negative charge, which demonstrated an increase in the adhesive energy. This increase in adhesion resulted from increased induction forces given the relatively high polarizability of HOPG and the preservation of the charge on ZnO surface. It was found that the additional negative charge can be preserved on the ZnO surface because there is an energy barrier since carbon and ZnO form a Schottky contact. Other materials with the same ionic properties of ZnO but with higher polarizability also demonstrated good adhesion to carbon. This result substantiates that their induced interaction can be facilitated not only by the polarizability of carbon but by any of the materials at the interface. The versatility to modify the magnitude of the induced interaction between carbon and an ionic material provides a new route to create interfaces with controlled interfacial strength.
ContributorsGalan Vera, Magdian Ulises (Author) / Sodano, Henry A (Thesis advisor) / Jiang, Hanqing (Committee member) / Solanki, Kiran (Committee member) / Oswald, Jay (Committee member) / Speyer, Gil (Committee member) / Arizona State University (Publisher)
Created2013
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Description
With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage

With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage tolerance than Pb-Sn alloys. Recently, a new class of alloys with trace amount of rare-earth (RE) elements has been discovered and investigated. In previous work from Prof. Chawla's group, it has been shown that cerium (Ce)-based Pb-free solder are less prone to oxidation and Sn whiskering, and exhibit desirable attributes of microstructural refinement and enhanced ductility relative to lanthanum (La)-based Sn-3.9Ag-0.7Cu (SAC) alloy. Although the formation of RESn3 was believed to be directly responsible for the enhanced ductility in RE-containing SAC solder by allowing microscopic voids to nucleate throughout the solder volume, this cavitation-based mechanism needs to be validated experimentally and numerically. Additionally, since the previous study has exhibited the realistic feasibility of Ce-based SAC lead-free solder alloy as a replacement to conventional SAC alloys, in this study, the proposed objective focuses on the in in-depth understanding of mechanism of enhanced ductility in Ce-based SAC alloy and possible issues associated with integration of this new class of solder into electronic industry, including: (a) study of long-term thermal and mechanical stability on industrial metallization, (b) examine the role of solder volume and wetting behavior of the new solder, relative to Sn-3.9Ag-0.7Cu alloys, (c) conduct experiments of new solder alloys in the form of mechanical shock and electromigration. The research of this new class alloys will be conducted in industrially relevant conditions, and the results would serve as the first step toward integration of these new, next generation solders into the industry.
ContributorsXie, Huxiao (Author) / Chawla, Nikhilesh (Thesis advisor) / Krause, Stephen (Committee member) / Solanki, Kiran (Committee member) / Mirpuri, Kabir (Committee member) / Arizona State University (Publisher)
Created2012
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Description
The following is a report that will evaluate the microstructure of the nickel-based superalloy Hastelloy X and its relationship to mechanical properties in different load conditions. Hastelloy X is of interest to the company AORA because its strength and oxidation resistance at high temperatures is directly applicable to their needs

The following is a report that will evaluate the microstructure of the nickel-based superalloy Hastelloy X and its relationship to mechanical properties in different load conditions. Hastelloy X is of interest to the company AORA because its strength and oxidation resistance at high temperatures is directly applicable to their needs in a hybrid concentrated solar module. The literature review shows that the microstructure will produce different carbides at various temperatures, which can be beneficial to the strength of the alloy. These precipitates are found along the grain boundaries and act as pins that limit dislocation flow, as well as grain boundary sliding, and improve the rupture strength of the material. Over time, harmful precipitates form which counteract the strengthening effect of the carbides and reduce rupture strength, leading to failure. A combination of indentation and microstructure mapping was used in an effort to link local mechanical behavior to microstructure variability. Electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) were initially used as a means to characterize the microstructure prior to testing. Then, a series of room temperature Vickers hardness tests at 50 and 500 gram-force were used to evaluate the variation in the local response as a function of indentation size. The room temperature study concluded that both the hardness and standard deviation increased at lower loads, which is consistent with the grain size distribution seen in the microstructure scan. The material was then subjected to high temperature spherical indentation. Load-displacement curves were essential in evaluating the decrease in strength of the material with increasing temperature. Through linear regression of the unloading portion of the curve, the plastic deformation was determined and compared at different temperatures as a qualitative method to evaluate local strength.
ContributorsCelaya, Andrew Jose (Author) / Peralta, Pedro (Thesis director) / Solanki, Kiran (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
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Description

Brundtland’s definition of sustainability is the ability to “meet the needs of the present without compromising the ability of future generations to meet their needs” (IISD, 2021). But what if there are no future generations? Social sustainability, the sector of sustainability that foregrounds the well-being and livelihoods of people (and

Brundtland’s definition of sustainability is the ability to “meet the needs of the present without compromising the ability of future generations to meet their needs” (IISD, 2021). But what if there are no future generations? Social sustainability, the sector of sustainability that foregrounds the well-being and livelihoods of people (and thereby continuation of humanity), is included in definitions within the sustainability field, but less developed in sustainability practice. In an effort to bridge this gap of knowledge, 14 U.S. cities and over 100 sustainability policies were analyzed for their social sustainability performance. An eight-item analytical framework that deals with differing areas of social equity guided the analysis. Results found that most cities’ sustainability departments fell short of truly addressing social sustainability concerns. Out of the eight items, the most frequently addressed were housing security and racial and gender equality whereas few, if any, cities addressed the more specific social concerns of immigration, technology and media, or arts/cultural preservation. Future research is recommended to gain a better understanding of the ways existing cities can improve in this area.

ContributorsTam, Joey (Co-author) / Weekes, Daniel (Co-author) / Brian, Jennifer (Thesis director) / Keeler, Lauren (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05