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Authors: Z.W. He, Xing Qin Liu, D.Y. Xu, Qiang Su, D.F. Guo, Y.Y. Wang
Abstract: The characteristic of nanoporous SiO2 thin film prepared by sol-gel method with catalyst HF was studied by scanning electron microscopy, Fourier transform infrared, HP analyzer series and ellipsometry. Results showed the incorporation of HF effectively adjusted the pore size and distribution, and lowered the leakage current density and dielectric constant. This might be related to the weak acidity of HF, which properly controlled the velocity of chemical reaction in solution, and to the introduction of strong Si-F bonds, which had the lower electronegative and the larger volume.
Authors: Liquan Guo, Yang Liu, Ju Sheng Ma
Abstract: Anodizing technique was applied to prepare insulated metal substrates (IMS) for BGA packaging. “Ideal” IMS used anodic film of aluminum as the insulating layer instead of epoxy, which led to higher thermal conductivity. But the thermal shock resistance of IMS is poor because of the great difference of thermal expansion coefficient between aluminum and its anodic film. In this study, different anodizing processes of aluminum were analyzed. The parameters, which can affect the thermal shock resistance of IMS, especially the surface temperature of Al substrate, were studied. The anodic film obtained with the optimized parameters of anodizing process had excellent performance, such as the resistivity was over 1013Ω·cm, the breakdown voltage was higher than 600V, and the most important thing was that it could resist thermal shocks between room temperature and 300°C. Then BGA packaging was successfully performed based on this IMS.
Authors: Su Dong Park, Byung Geol Kim, Hee Woong Lee
Abstract: Electric conducting behavior, sectional residual stress and texture in deformed Al-Zr alloy were investigated in order to investigate effect of deformation on electric conductance. {111} textures were developed in the wire of deformed Al-Zr alloy and most strong intensity of {111} texture was observed at the core in the cross section of the wire. Residual stress was mainly measured at the surface and , especially, measured at the core in the case of 4.5Φ wire, also, electric conductance was higher at the surface than at the core. This means that electric conductance might be affected by distribution of the residual stress.
Authors: Guohai Chen, Ju Sheng Ma, Zhi Ting Geng
Abstract: Sn-Pb solder alloys, widely used in electronic industry, will be restricted because of the toxicity of Pb. That is paramount importance that developing viable alternative lead-free solders for electronic assemblies. Sn-Ag-Cu alloys are better alternative because of its good performance. But they have a melting temperature of 217-225°C that is much higher than that of Sn-Pb eutectic alloy, 183°C. It may be very difficulty to realize industrialization. Sn-Ag-Cu-Ga solder alloys have been studied in this paper, including a series of properties tests, such as melting point, hardness, shear strength and solderability. The best composition of Sn-Ag-Cu-Ga lead-free solder alloy has been obtained.
Authors: Byung Geol Kim, Su Dong Park, Shang Shu Kim, Hee Woong Lee
Abstract: As a way to expand electric capacity in power line with hovering of electric power demand, STACIR/AW (super thermal-resistant Al alloy conductors Al-clad Invar-reinforced) overhead conductor which cans double ampacity has been developed. The STACIR/AW power line is mechanically composite stranded wire composed of INVAR/AW stranded wire as core for sag control and heat-resistant aluminum alloy for delivering doubled electric current. Recently, in order to ensure stable line operation and to predict its span of life, the changes of thermal properties for STACIR/AW have been investigated. In the present work, the changes of strain with temperature and the creep behavior as important factors in sag control will be presented. The transition temperature of STACIR/AW 410sqmm was estimated approximately 130°C and the creep rates were decreased with temperatures.
Authors: J.F. Liang, J.K. Yu, Y.Q. Quan
Abstract: The effects of interfacial thickness and temperature on thermal conductivity and CTEs of Al/SiC packaging materials were investigated. The interfacial thermal conductivity and thickness have significant influence on the thermal conductivity of the Al/SiC packaging materials, while the SiC size has slight influence on that of the Al/SiC packaging materials. The experiment results of thermal conductivity are similar to Hassleman model and simulation results. Schapery model can be used to calculate the CTEs of composites when temperatures are lower(50~100°C) and Kerner model can be used when temperatures are higher(300~450°C). The CTEs of composites will increase more quickly than that by three models when temperatures are between 100°C and 300°C.
Authors: Hyun Jae Yoo, Chang Ho Lee, Yong Ho Park, Ik Min Park
Abstract: Effect of Au (0-0.3 wt.%) on the thermoelectric properties of Bi1Sb3Te6 alloy prepared by mechanical alloying process has been investigated. The Seebeck coefficient decreases with Au content. The Seebeck coefficient of Au-free alloy at room temperature reaches a value of 250 µV/K, which is the maximum. Because of the increased power factor, the figure of merit increases with Au content up to 0.03 wt. % and its value at room temperature is about 2.8×10-3/K, the highest value among the prepared alloys. The Hall measurement shows that the carrier concentration increases with Au content, which explains the reason why the power factor has increased. The XRD patterns show that the intensities of (2 0 5), (0 0 18), (0 2 10), (1 0 19), (1 2 5), and (2 1 10) planes increase with Au content. The atomic distance of these complex planes is longer than that of other main planes, and the chemical bonding strength of these complex planes between constitutional elements is weaker than that of other main planes. As a result, a portion of electrons as minor carrier is trapped into accept level of Au atoms and/or clusters. The XPS observation result, which a portion of Au atoms is chemically shifted in contrast to Bi, Sb and Te atoms are not, explains that Au behaves as an acceptor.
Authors: Yan Wang, Yang Liu, Ju Sheng Ma, Zhaowen Dong, Mingli Yin
Abstract: Fine Au powders with spherical morphology and good dispersivity were produced. The average particle size is 1~2m. The influences of constituents on the rheology of organic vehicles were investigated by orthogonal design method. Consequently, the compatible Au thick film pastes for LTCC substrate have been prepared. SEM was carried out to study the sintering behaviors and microstructures of the buried pastes with LTCC substrate. These pastes have high electrical conductivity (less than 3m/sq.), reliable wire bond strength (greater than 9 grams, 25m Au wire) and fine line printability (as small as 80m). The via filling technology was also discussed in this paper.
Authors: Yang Liu, Yan Wang, Ju Sheng Ma
Abstract: With the wide application of SMT, mass chip components have been applied including tantalum capacitor. A fuse buried in a capacitor can protect the whole system of merit. In the paper a titanium nickel alloy with vanadium addition has been developed as a fuse material. Several alloy wires with different diameters have been used in the fusing experiment. The influencing factor have been discussed that a few factors including diameter, chucking and so on affect the fusing current. Analyses on the fuse wires have been investigated with SEM, XRF and XRD to measure the composition of alloy wires.
Authors: D.H. Kim, T.S. Kim, B.K. Ahn, H.Y. Shin, Dong-Gu Lee, H.K. Cho, Young Rae Cho
Abstract: Carbon nanotubes have attracted considerable attention because their high aspect ratio leads to a large electric field enhancement and a low operating voltage. The dependence of environmental gases such as Ar, O2 on the emission current from carbon nanotube emitters was examined in this study. Based on our experiments, the current density is decreased in single-wall carbon nanotubes (SWNTs), but is increased in multi-wall carbon nanotubes (MWNTs) as the vacuum level decreases from 10-7 Torr to 10-4 Torr by the inflow purging gases. The current density subsequently recovered as the vacuum level increased to 10-7 Torr when gas inflow stopped. From those results, we conclude that the MWNTs have completely different degradation characteristics in comparison to SWNTs. The increased current density of an MWNT in the high-pressure range of 10-4 Torr is a significant finding and would be widely applicable to low cost vacuum packages.

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