Authors: Yun Sung Moon, Jae Ho Lee, Tae Sung Oh, Ji Young Byun
Abstract: The codeposition behavior of submicron sized diamond with nickel from nickel
electrolytes has been investigated. Electroplating of diamond dispersed nickel composites was
carried out on a rotating disk electrode (RDE). The effects of current type and current density on
the electrodeposited Ni-diamond composite coating were investigated. The effects of pH and
surfactants on the composite coating were also investigated. The hardness of coating was
measured with varying electroplating conditions. As diamond was incorporated into the coating,
the hardness of coating as well as the wear resistance was improved. The surface morphologies of
the Ni-diamond composite coatings were observed using FESEM.
1597
Authors: Teck Su Oh, Jae Ho Lee, Ji Young Byun, Tae Sung Oh
Abstract: In Ni-SiC composite coating, the SiC content is dependent on the surface properties of
SiC particles. As sulfuric acid has a strong dehydration force, addition of sulfuric acid in the Ni
sulfamate bath changed the surface properties of SiC particles, affecting the codeposition behavior
of SiC particles. Also the additives such as SDS affect the electrodeposition behavior of the Ni-SiC
composite coating. In this study, effects of the HSO4
‾ and the current density on the
electrodeposition behavior of the Ni-SiC composite coating have been investigated. The Ni-SiC
composite coatings were electrodeposited at current densities of 50~200mA/cm2. The surface and
cross-sectional morphologies of the Ni-SiC composite coatings were observed using SEM, and their
mechanical properties were characterized with micro-Vikers hardness.
1533
Authors: Boo Yang Jung, Eun Kyoung Choi, Young Soo Jeon, Kwang Yong Lee, Kwang Seok Seo, Tae Sung Oh
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.
25
Authors: Tae Jin Yoon, Yong Ho Park, Tae Sung Oh
Abstract: Electrodeposition behavior and thermoelectric properties of the p-type (Bi,Sb)2Te3 films
were investigated for thermoelectric energy conversion and nanowire applications. Composition and
thermoelectric properties of the electrodeposited (Bi,Sb)2Te3 films were strongly dependent on the
electrodeposition current density. The (Bi,Sb)2Te3 films electrodeposited in a 30mM solution of the
5mM Bi-15mM Sb-10mM Te concentration at current densities of 0.3~0.5 mA/cm2 exhibited the
power factors of 2~3.4 ×10-4 W/K2-m, which were equivalent to the values reported for the
sputter-deposited (Bi,Sb)2Te3 films.
917
Authors: Kwang Yong Lee, Tae Sung Oh
Abstract: The p-type (Bi0.2Sb0.8)2Te3/(Pb0.7Sn0.3)Te functional gradient material (FGM) was
fabricated by hot-pressing the mechanically alloyed (Bi0.2Sb0.8)2Te3 and the 0.5 at% Na2Te-doped
(Pb0.7Sn0.3)Te powders. Also, the n-type Bi2(Te0.9Se0.1)3/PbTe FGM was processed by hot-pressing
the mechanically alloyed Bi2(Te0.9Se0.1)3 and the 0.3 wt% Bi-doped PbTe powders. With △T larger
than 300°C, the p-type (Bi0.2Sb0.8)2Te3/(Pb0.7Sn0.3)Te FGM exhibited larger thermoelectric output
power than those of the (Bi0.2Sb0.8)2Te3 and the 0.5 at% Na2Te-doped (Pb0.7Sn0.3)Te alloys. For the
n-type Bi2(Te0.9Se0.1)3/PbTe FGM, the thermoelectric output power superior to those of the
Bi2(Te0.9Se0.1)3 and the 0.3 wt% Bi-doped PbTe was predicted at △T larger than 300°C.
1493
Authors: J.H. Choi, Tae Sung Oh
Abstract: Ferroelectric characteristics of the 400 nm-thick SrxBi2.4Ta2O9(0.7≤x≤1.3) thin films processed by metalorganic decomposition were investigated, and electrical properties of the Pt/Sr0.85Bi2.4Ta2O9/TiO2/Si structure prepared using TiO2 buffer layer were characterized. The Sr-deficient SrxBi2.4Ta2O9 films exhibited well-developed ferroelectric hysteresis curves compared to those of the Sr-excess films. The Sr0.85Bi2.4Ta2O9 film exhibited optimum ferroelectric properties, such as high remanent polarization and low leakage current density, among SrxBi2.4Ta2O9 films. A
memory window of the Pt/SrxBi2.4Ta2O9/TiO2/Si structure was dependent upon the coercive field of the SrxBi2.4Ta2O9 film, and the Pt/SrxBi2.4Ta2O9/TiO2/Si exhibited a maximum memory window of 1.3 V at the sweeping voltage of ±5 V.
477
Authors: J.H. Choi, B.Y. Jung, S.W. Jun, Y. Kim, Tae Sung Oh
Abstract: Reactions between 48Sn-52In solder and under bump metallurgies(UBM) such as 100nmTi/8µm Cu and 300nm Al/400nm Ni(V)/400nm Cu have been investigated, and the shear strength of 48Sn-52In solder bumps on each UBM has been evaluated. While intermetallic compounds with two different morphologies were continuously thickened on Ti/Cu with repeating the reflow process, the intermetallics on Al/Ni(V)/Cu spalled into the solder with increasing the number of reflow times.
The solder bumps on Ti/Cu exhibited higher shear strength than those on Al/Ni(V)/Cu.
401
Authors: Y.H. Lee, Kwang Yong Lee, Jin Soo Bae, Jae Ho Lee, Ji Young Byun, D.B. Hyun, Tae Sung Oh
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.
377