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dc.contributor.authorSadiq, Muhammaden_US
dc.date.accessioned2012-09-20T18:18:13Z
dc.date.available2012-09-20T18:18:13Z
dc.date.issued2012-05-22en_US
dc.identifier.urihttp://hdl.handle.net/1853/44762
dc.description.abstractSn-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.en_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectMicroelectronicsen_US
dc.subjectInterMetallic compounds (IMCs)en_US
dc.subjectMicrostructure evolutionen_US
dc.subjectThermal coarsening (Aging)en_US
dc.subjectCreep behaviouren_US
dc.subjectCharacterizationen_US
dc.subjectElectronic packagingen_US
dc.subjectWettabilityen_US
dc.subjectNanoindentationen_US
dc.subjectNanotechnologyen_US
dc.subjectRare-earth elements (Lanthanum)en_US
dc.subjectLead-free solderen_US
dc.subject.lcshLanthanum
dc.subject.lcshLead-free electronics manufacturing processes
dc.subject.lcshSolder and soldering
dc.subject.lcshMicrostructure
dc.titleDesign and fabrication of lanthanum-doped Sn-Ag-Cu lead-free solder for next generation microelectronics applications in severe environmenten_US
dc.typeDissertationen_US
dc.description.degreePhDen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.advisorCommittee Chair: Cherkaoui, Mohammed; Committee Member: Busso, Esteban; Committee Member: Neu, Richard; Committee Member: Ougazzaden, Abdallah; Committee Member: Zhu, Tingen_US


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