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Fabrication and Characterization of Sn-Ag-Cu Solder Reinforced with Al2O3 Nano Particles Employing Mechanical Alloying

Jafari Azar, Vahid | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47802 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kokabi, Amir Hossein; Simchi, Abdolreza
  7. Abstract:
  8. Many regulations have been introduced over the world to urge the elimination of lead and lead containing solders, due to increasing pressure of the environmental and health concerns associated with lead-containing solders in the electronics industry. Therefore, efforts to develop and promote lead-free soldering have recently intensified. Conventional solder technology may not guarantee the required performance at such pitches due to problems such as higher diffusivity and the softening nature of the solder. To solve these problems, efforts have been made to develop solders with a low melting point, higher strength, better microstructure properties, and high creep resistance. Recently lead-free nano composite solders have been identified as potential materials with higher microstructure stability and better mechanical properties as compared to conventional solders. An important issue in these solders is uniform distributing of nanoparticles in solder matrix. In this study Sn–3.5Ag–0.7Cu alloy powders with different amounts of Al2O3 nanoparticles were successfully fabricated by mechanical alloying (MA). During MA, Sn, Ag and Cu powders were deformed, overlapped and cold welded together to form lamellar composites. The lamellar composites were then transformed into equiaxial particles. The milled powders were composed of a supersaturated solid solution, named Sn(Ag, Cu), and intermetallic compound (IMC) of Ag3Sn. The melting point of the 64 h milled Sn–3.5Ag–0.7Cu monolithic and nanocomposite powders were about 221◦C. After soldering of paste and hot-pressed powder solder on Cu pads at 260◦C, the solder did not melted completely and there was much dross in joint gap
  9. Keywords:
  10. Lead Free Solders ; Mechanical Alloying ; Aluminum Oxide Nanoparticle ; Nanocomposite Solder ; Aluminum Oxide Reinforcement Nanoparticles ; Tin-Silver-Copper Solder

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