Strengthening mechanism of nano-Al2O3 particles reinforced Sn3.5Ag0.5Cu lead-free solder

• Published in: Journal of materials science. Materials in electronics Vol. 22; no. 8; pp. 1021 - 1027
• Main Authors: Chuang, T. H., Wu, M. W., Chang, S. Y., Ping, S. F., Tsao, L. C.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 2011; Springer
• Subjects: Applied sciences; Brazing. Soldering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density; Eutectic temperature; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nanocomposites; Nanomaterials; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Optical and Electronic Materials; Particulate composites; Physics; Solders; Thermal expansion; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Fine Microscopic Crack; Solder Alloy; Pb37Sn Composite Solder; Composite Solder Specimen; Composite Solder; Grain boundaries; Differential scanning calorimetry; Strengthening; Ductility; Doping; Doped materials; Mechanical properties; Solder metal; Spacing; Melting points; Precipitates; Nanoparticles; Integrated circuit bonding; Hardening; Microporosity; Composite materials; III-VI compound; Lead free soldering; Thermal expansion coefficient; Lead free solder; Thermal analysis; Microstructure; Alumina; Soldered joints
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-010-0253-1

To improve the properties of the eutectic Sn3.5Ag0.5Cu lead-free solder, various amounts of mixed nano-Al 2 O 3 particles were added. The microstructure, thermal analysis, density, thermal expansion coefficient (CTE), and mechanical behavior were studied. The results of differential scanning calorimetry (DSC) indicate that the melting point of the composite solder doped with nano-Al 2 O 3 particles is slightly higher that of the Sn3.5Ag0.5Cu lead-free solder and has a eutectic peak. The Sn3.5Ag0.5Cu composite solders exhibited lower density values and thermal expansion coefficient (CTE) values than did the unreinforced solder matrix. Compared to solder without the addition of nano-Al 2 O 3 particles, the formation of dendritic β-Sn grains, the Ag 3 Sn phase average size, and the spacing of lamellae decreased significantly in the composite solder matrix. The mechanical properties also improved with increasing weight percentages of nano-Al 2 O 3 particles. However, the ductility of the Sn3.5Ag0.5Cu composite solder decreased. For the addition of 1 wt% nano-Al 2 O 3 particles, microporosity was observed both at and along the grain boundary regions, coupled with the presence of second-phase particles (i.e. nano-Al 2 O 3 and Ag 3 Sn).