Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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- Creators: Mcmullan, Kyle Jonathan
- Creators: Xie, Huxiao
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 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
Description
The financial feasibility of NextPotential's X-doped photocatalyst is uncertain, the outcome depends on how much the material cost becomes reduced due to mass production techniques. If carbon taxes continue on the current trend the photocatalyst is highly likely to become financially feasible. Without carbon taxes, it is still likely the photocatalyst will achieve economical feasibility. The land area required by the photocatalyst is a feasible size. The minimal environmental downsides are that more land will be used and water will be used, but both of these are minimal compared to the benefit of eliminating carbon emissions.
ContributorsMcmullan, Kyle Jonathan (Co-author) / Lahpai, Mun (Co-author) / Donnelly, Connor (Co-author) / Puzhaev, Boris (Co-author) / Adams, James (Thesis director) / Krause, Stephen (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor)
Created2015-05