Papers by Author: Kwang Yong Lee

Abstract: For flip-chip process of RF system-on-packages(SOP), double bump bonding processes were investigated. Sn-Ag and Sn solder joints were formed by the reflowed double bumping process, and Sn/In/Sn bump joints were fabricated by the non-reflowed double bump bonding process. The height-to-size ratios of 0.78 and 0.65 were obtained for the reflowed double bumping and the non-reflowed bumping, respectively. Average contact resistance of the reflowed Sn-Ag and Sn solder joints was about 13m/ which was much lower than 24~33m/ of the non-reflowed Sn/In/Sn bump joints. The reflowed solder double bumping method is more suitable for flip-chip process of RF-SOP than the non-reflowed double bump bonding.

Abstract: 20 vol.% aluminum borate whisker (Al18B4O33w) reinforced AC4CH alloy composite was fabricated by squeeze casting method. The matrix is controlled its impurities, which make metal alloys, especially AC4CH alloy that is made by restraining 0.2% Iron and aluminum to make a matrix material. The perform of composite materials was made from Al18B4O33w with 5% regulated three kinds of inorganic binders, SiO2, Al2O3 and TiO2 sol, respectively and then sintered at 1373K. The composites were obtained by squeeze cast infiltration of the molten alloy to the perform. Then it was squeeze casting into the matrix. The status of adhesions of whisker perform was Observed by SEM. Micro-Vickers hardness and tensile properties at the room temperature were estimated. Al18B4O33w/AC4CH composites containing TiO2 sol has excellent properties on tensile properties and micro-vickers hardness compared with the other composites without inorganic binder, containing SiO2 and Al2O3 sol inorganic binder.

Abstract: Electroplating behavior of Bi ₂Te ₃ and thermoelectric properties of the electroplated Bi ₂Te ₃ films were investigated for nanowire application. Composition, microstructure, and thermoelectric properties of the electroplated Bi-Te films were strongly dependent upon composition of the electroplating solutions and plating current density. While the power factor of the Bi ₂Te ₃ film plated at a current density of 1×10^-4 A/cm² was 1.75×10^-4 W/K²-m, the film formed at 5×10^-4 A/cm² exhibited the value of 3.5×10^-4 W/K²-m. Substantial pore filling was achieved with electrodeposition of Bi ₂Te ₃ for the alumina template with 200 nm pores.