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Fast Spreading of Liquid SnPb Solder on Gold-coated Copper Wheel Pattern

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journal of Materials Science & Technology 2010年第12期26卷 1143-1147页

作者： Wei Liu Lei Zhang k.j. Hsia j.k. shang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

The reactive Sn63Pb37 spreading on patterned film structures was examined in a reducing atmosphere （H2 5%＋Ar 95%）. Liquid solder spreading was observed to follow the wheel pattern made of Au/Cu thin film. At the center, a liquid cap was formed around the hub by viscous spreading of the liquid front. Ahead of the main viscous flow front, a liquid film was found to be extended on thin Au-Cu lines at a fast rate to a great distance by rapid Sn-Au chemical reaction.

关键词： Wetting Reactive wetting Spreading Solder Thin film pattern Liquid film

Inhibition of Electromigration in Eutectic SnBi Solder Interconnect by Plastic Prestraining

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journal of Materials Science & Technology 2011年第11期27卷 1072-1076页

作者： X.F. Zhang H.Y. Liu j.D. Guo j.k. shang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign. Urbana. IL 61801. USA

Plastic prestraining was applied to a solder interconnect to introduce internal defects such as dislocations in order to investigate the interaction of dislocations with electromigration damage. Above a critical prestrain, Bi interfacial segregation to the anode, a clear indication of electromigration damage in SnBi solder inter- connect, was effectively prevented. Such an inhibiting effect is apparently contrary to the common notion that dislocations often act as fast diffusion paths. It is suggested that the dislocations introduced by plastic prestraining acted as sinks for vacancies in the early stage of the electromigration process, but as the vacancies accumulated at the dislocations, climb of those dislocations prompted recovery of the deformed samples under current stressing, greatly decreasing the density of dislocation and vacancy in the solder, leading to slower diffusion of Bi atoms.

关键词： Electromigration Interfacial segregation Prestrain Dislocation Vacancy

First-principles Investigation of Bi Segregation at the Solder Interface of Cu/Cu_3Sn(010)

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journal of Materials Science & Technology 2010年第12期26卷 1057-1062页

作者： X.Y. Pang Z.Q. Liu S.Q. Wang j.k. shang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign IL 61801 USA

Density functional theory was employed to investigate the bismuth segregation at Cu/Cu3Sn（010） interface. Five initial constructions were introduced by adopting the adhesion energy criterion. Among them, the so-called ＂between-Cu＂ construction in which the interface Cu atoms of Cu slab locate along Cu-Cu bond direction in Cu3Sn slab was found to be the most energy-favored at an adhesion energy of 1.96 j/m^2. Based on this construction, five possible segregation sites were examined, and the most likely segregation site was determined with adhesion energy as low as 1.06 j/m^2, which was almost half of the initial one. Comparing with other sitest adhesion energies, it was concluded that size effect took a large part in embrittlement. The analyses of atomic structure and electronic density revealed that the slabs shifted away from interfaces due to bismuth segregation, and the atoms around Bi atom were Dressed away. This calculated work agreed aualitativelv with reported experimental results.

关键词： First-principles calculation Segregation Bismuth Interface SnBi solder

Effects of Current Stressing on Shear Properties of Sn-3.8Ag-0.7Cu Solder joints

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journal of Materials Science & Technology 2010年第8期26卷 737-742页

作者： X.j. Wang Q.L. Zeng Q.S. Zhu Z.G. Wang j.k. shang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

Effects of electromigration on microstructure, shear strength, and fracture behavior of solder joints were investigated by single-ball shear samples of eutectic Sn-3.8Ag-0.7Cu （SAC） joined by Cu plates at two sides. The electromigration tests were conducted at a current density of about 1.1×10^3 A/cm2 and a working temperature of about 83℃. The results showed that the shear strength and flow stress decreased greatly after current stressing. Such a decrease was associated with no significant loss of the fracture strain at short electromigration but a great reduction in the fracture strain after long-term current stressing. The variation of the fracture strain with the electromigration time was shown to result from the shift of the fracture surface from the center of the solder towards the intermetallic compound （IMC） interface at the cathode.

关键词： Strength Fracture strain Voids Solder

Synthesis of Single-Crystal TiO_2 Nanowire Using Titanium Monoxide Powder by Thermal Evaporation

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journal of Materials Science & Technology 2012年第5期28卷 385-390页

作者： Z.G.shang Z.Q.Liu P.j.shang j.k.shang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of TiO 2 . According to microstructural observations, the nanowires have two typical morphologies, a long straight type and a short tortuous type. The straight nanowires were obtained at a wide temperature range of 900–1050 ℃, while the tortuous ones were formed below 900 ℃. Transmission electron microscopy characterization revealed that both the straight and the tortuous nanowires are single-crystal rutile TiO 2 . The preferential growth direction of the nanowires was determined as [110] orientation according to electron diffraction and high-resolution image analyses. The morphological change of TiO 2 nanowires was discussed by considering the different atomic diffusion rates of Ti atoms caused by the phase transformation in Ti substrate at around 900 ℃.

关键词： Rutile-TiO 2 Alloy nanowires Transmission electron microscopy (TEM) characterization Crystal structure identification Growth mechanism Thermal evaporation

Tunable Reactive Wetting of Sn on Microporous Cu Layer

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journal of Materials Science & Technology 2012年第4期28卷 379-384页

作者： Qingquan Lai Lei Zhang Cai Chen j.k.shang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

Wetting of microporous Cu layer by liquid Sn resulted in contact angles from 0 to 33 deg., tunable by varying wetting temperature and porous microstructure. The wetting was dominated by the interracial metallurgical r... 详细信息

关键词： Wetting Porous material Soldering

Solderability of Electrodeposited Fe-Ni Alloys with Eutectic SnAgCu Solder

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journal of Materials Science & Technology 2007年第6期23卷 811-816页

作者： jianjun GUO Lei ZHANG Aiping XIAN j.k.shang Sh-enyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

Solderabilities of electrodeposited Fe-Ni alloys with SnAgCu solder were examined by wetting balance measurements and compared to those of pure Ni and pure Fe platings. Excellent solderability was found on the Ni-52Fe plating as both the wetting force and kinetics approached or exceeded those on the pure Ni. However, upon further increase in Fe content to 75 at. pct, the solderability of the alloy was severely degraded even though it was still better than that of the pure Fe plating. X-ray photoelectron spectroscopy showed that such a strong dependence of solderability on Fe content is related to the much thinner, incomplete oxide coverage of Ni-rich plating surface.

关键词： Solderability FeNi alloys Lead-free solders Wetting

Effects of carbon content on the microstructure and tensile properties of a low-density steel

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International journal of Minerals,Metallurgy and Materials 2025年第02期 391-401页

作者： Yongxuan shang Mingyu Fan Shuyong jiang Zhongwu Zhang key Laboratory of Superlight Materials and Surface Technology Ministry of Education College of Materials Science and Chemical Engineering Harbin Engineering University State key Laboratory of Metal Material for Marine Equipment and Application Iron & Steel Research Institute of Ansteel Group Corporation

Carbon can change the phase components of low-density steels and influence the mechanical properties. In this study, a new method to control the carbon content and avoid the formation of δ-ferrite by decarburization treatment was proposed. The microstructural changes and mechanical characteristics with carbon content induced by decarburization were systematically examined. Crussard–jaoul(C–j) analysis was employed to examine the work hardening characteristics during the tensile test. During decarburization by heat treatments, the carbon content within the austenite phase decreased, while Mn and Al were almost unchanged; this made the steel with full austenite transform into the austenite and ferrite dual phase. Meanwhile,(Ti,V)C carbides existed in both matrix phase and the mole fraction almost the same. In addition, the formation of other carbides restrained. Carbon loss induced a decrease in strength due to the weakening of the carbon solid solution. For the steel with the single austinite, the deformation mode of austenite was the dislocation planar glide, resulting in the formation of microbands. For the dual-phase steel, the deformation occurred by the dislocation planar glide of austenite first, with the increase in strain, the cross slip of ferrite took place, forming dislocation cells in ferrite. At the late stage of deformation, the work hardening of austinite increased rapidly, while that of ferrite increased slightly.

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Electrostatic-Aerodynamic Compression in Hypersonic Cylindrical Inlet

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Communications in Computational Physics 2008年第9期4卷 838-859页

作者： j.S.shang Department of Mechanics and Materials Engineering Wright State UniversityDaytonOH 45435USA.

Hypersonic magneto-fluid-dynamic interaction has been successfully performed as a virtual leading-edge strake and a virtual cowl of a rectangular *** a side-by-side experimental and computational study,the magnitude of the induced compression was found to depend on configuration and electrode *** better understand the interacting phenomenon the present investigation is focused on a direct current discharge at the leading edge of a cylindrical inlet for which validating experimental data is *** present computational result is obtained by solving the magneto-fluid-dynamics equations at the low magnetic Reynolds number limit and using a nonequilibrium weakly ionized gas model based on the drift-diffusion *** numerical simulation provides a detailed description of the intriguing *** validation with experimental measurements,the computed results further quantify the effectiveness of a magneto-fluid-dynamic compression for a hypersonic cylindrical inlet.A minuscule power input to a direct current surface discharge of 8.14 watts per square centimeter of electrode area produces an additional compression of 6.7 percent for a constant cross-section cylindrical inlet.

关键词： Magnetohydrodynamics hypersonic flows