• Applied Microscopy
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• v.25 no.1
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• pp.130-138
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• 1995

TEM specimen preparation methods have been examined to characterize Cu oxide particles in the polyimide film. Polyimide films were prepared by coating polyamic acid onto Cu films which had been deposited on TEM-mask and glass substrates and Cu foil, followed by thermal curing. In case of TEM-mask, direct observation was possible without further preparation. In other cases, TEM specimen were made by separating polyimide film from the substrate. Polyimide films were removed from glass and Cu foil by dissolving glass in HF solution and Cu foil in $H_{2}SO_{4}$ solution. TEM-mask observation confirms that fine $Cu_{2}O$ particles precipitate in the polyimide as a result of reaction of polyamic acid with Cu. However $Cu_{2}O$ particle reacts with HF and $H_{2}SO_{4}$ solution during dissolving the substrate and interpretation could be misled. It is concluded characterization of $Cu_{2}O$ particle in polyimide using TEM-mask is better than other methods.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.186-193
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• 2014

A thin Cu seed layer for electroplating has been employed for decades in the miniaturization and integration of printed circuit board (PCB), however many problems are still caused by the thin Cu seed layer, e.g., open circuit faults in PCB, dimple defects, low conductivity, and etc. Here, we studied the effect of heat treatment of the thin Cu seed layer on the deposition rate of electroplated Cu. We investigated the heat-treatment effect on the crystallite size, morphology, electrical properties, and electrodeposition thickness by X-ray diffraction (XRD), atomic force microscope (AFM), four point probe (FPP), and scanning electron microscope (SEM) measurements, respectively. The results showed that post heat treatment of the thin Cu seed layer could improve surface roughness as well as electrical conductivity. Moreover, the deposition rate of electroplated Cu was improved about 148% by heat treatment of the Cu seed layer, indicating that the enhanced electrical conductivity and surface roughness accelerated the formation of Cu nuclei during electroplating. We also confirmed that the electrodeposition rate in the via filling process was also accelerated by heat-treating the Cu seed layer.

• The Korean Journal of Pharmacology
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• v.23 no.1
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• pp.25-31
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• 1987

The present study examines firstly, the inhibition of collagen gelation to explore the possible involvement of $Cu^{++}$-catalyzed peroxidation in rheumatoid arthritis and secondly, the effect of sodium salicylate on this peroxidative reaction to provide a possible explanation for its mechanism of anti-inflammatory action. Incubation of collagen obtained from rat skin with $Cu^{++}$ and $H_2O_2$ resulted in the inhibition of gelation in terms of maximal turbidity and lag phase, but either $Cu^{++}$ or $H_2O_2$ alone essentially gave no effect in the collagen gelation. In the presence of sodium salicylate the inhibited gelation of collagen induced by $Cu^{++}$ and $H_2O_2$ was reversed with the dependency of the concentration of sodium salicylate. Moreover, the rate of $H_2O_2$ decomposition by $Cu^{++}$ was accelerated by sodium salicylate and this decomposition of $H_2O_2$ was found to be saturable in terms of concentration of this drugs. Thus it can be expected that $Cu^{++}$ -catalyzed peroxidation attacks collagen resulting in change of structural or functional integrity of collagen, and sodium salicylate may act on this peroxidative process, possibly through the enhancement of catalatic action of $Cu^{++}$. From these results $Cu^{++}$-catalyzed peroxidation can be in part responsible for degradation of joint tissue in rheumatoid arthritis and sodium salicylate may exert its anti-inflammatory action by this peroxidative reaction.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.9-15
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• 2009

Compared to the flip-chip process using solder bumps, Cu pillar bump technology can accomplish much finer pitch without compromising stand-off height. Flip-chip process with Cu pillar bumps can also be utilized in radio-frequency packages where large gap between a chip and a substrate as well as fine pitch interconnection is required. In this study, Cu pillars with and without Sn caps were electrodeposited and flip-chip-bonded together to form the Cu-Sn-Cu sandwiched joints. Contact resistances and die shear forces of the Cu-Sn-Cu sandwiched joints were evaluated with variation of the height of the Sn cap electrodeposited on the Cu pillar bump. The Cu-Sn-Cu sandwiched joints, formed with Cu pillar bumps of $25-{\mu}m$ diameter and $20-{\mu}m$ height, exhibited the gap distance of $44{\mu}m$ between the chip and the substrate and the average contact resistance of $14\;m{\Omega}$/bump without depending on the Sn cap height between 10 to $25\;{\mu}m$.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.6
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• pp.757-761
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• 2010

This study was conducted to assess the effects of organic and inorganic copper on performance in growing pigs. A total of 100 pigs, average age 63 d and initial body weight 21.46${\pm}$1.13 kg, were assigned to five treatment groups. Dietary treatments included i) CON (basal diet, 0 ppm Cu), ii) T1 (basal diet with 67 ppm Cu as cupric sulfate, $CuSO_4$), iii) T2 (basal diet with 134 ppm Cu as $CuSO_4$), iv) T3 (basal diet with 67 ppm Cu as cupric methionate, CuMet) and v) T4 (basal diet with 134 ppm Cu as CuMet). Throughout the entire experimental period, ADG (average daily gain), ADFI (average daily feed intake) and G/F (gain: feed) ratios showed no significant differences. The dry matter digestibility was improved in the T1, T2, T3, and T4 treatments (p<0.05), as compared with CON. Nitrogen digestibility was improved in the T3 treatment group as compared with CON (p<0.05). As compared with the T1 treatment group, fecal pH values were improved in the CON, T3, and T4 treatment groups (p<0.05). Fecal Cu concentrations were significantly lower in the CON, T3, and T4 treatment groups than in T1 and T2 (p<0.05). The incidence of diarrhea was reduced when the pigs were fed on the T2, T3, and T4 diets as compared with CON. In conclusion, diets supplemented with 67 or 134 ppm Cu as CuMet may prove effective in improving nutrient digestibility and fecal pH value in growing pigs, and fecal Cu concentrations may be reduced by CuMet supplementation.

• Journal of the Korean Ceramic Society
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• v.36 no.8
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• pp.835-842
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• 1999

Si3N4 -Si3N4 joints were made using Ag-Cu-Ti and Ag-Cu-In-Ti via brazing method and the change in joint strength was investigated after heat treatment at $400^{\circ}C$ or $650^{\circ}C$ for up to 2000h. The initial strength of as-brazed joints with Ag-Cu-In-Ti was lower but the reduction of the strength was less dramatic than that with Ag-Cu-Ti. The joints made of a new brazing alloy Au-Ni-Cr-Mo-Fe which is developed for high temperature applications were heat-treated at $650^{\circ}C$ for 1000h. As the heat treatment time increased the bond strength increased. The results of the joining system with Mo or Cu interlayer showed that the strength of the joint with Mo interlayer was higher but the system incurred problems in joint production Also it was found from oxidation experiment that Ti and In affected the oxidation resistance of brazing alloy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.565-566
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• 2006

Slurry used in metal chemical mechanical polishing normally consists of an oxidizer, a complexing agent, a corrosion inhibitor and an abrasive. This paper investigates effects of citric acid as a complexing agent for Cu CMP with $H_2O_2$ as an oxidizer. In order to study chemical effects of a citric acid, x-ray photoelectron spectroscopy were performed on Cu sample after Cu etching test. XPS results reveal that CuO, $Cu(OH)_2$ layer decrease but Cu/$Cu_2O$ layer increase on Cu sample surface. To investigate nanomechanical properties of Cu sample surface, nanoindentation was performed on Cu sample. Results of nanoindentation indicate wear resistance of Cu Surface decrease. According to decrease of wear resistance on Cu surface, removal rate increases from $285\;{\AA}/min$ to $8645\;{\AA}/min$ in Cu CMP.

• Journal of Korea Foundry Society
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• v.42 no.5
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• pp.273-281
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• 2022

In order to understand the solidification behavior and microstructural evolution of the Al-Cu-Si ternary eutectic alloy system, changes of the microstructure of the Al-Cu-Si ternary eutectic alloy with different cooling rates were investigated. When the mold preheating temperature is 500℃, primary Si and Al2Cu dendrites are observed, with (α-Al+Al2Cu) binary eutectic and needle-shaped Si subsequently observed. In addition, even when the mold preheating temperature is 300℃, primary Si and Al2Cu dendrites can be observed, and both (α-Al+Al2Cu+Si) areas observed and areas not observed earlier appear. When the mold preheating temperature is 150℃, bimodal structures of the binary eutectic (α-Al+Al2Cu) and ternary eutectic (α-Al+Al2Cu+Si) are observed. When the preheating temperature of the mold is changed to 500℃, 300℃, and 150℃, the greatest change is in the Si phase, and upon reaching the critical cooling rate, the ternary eutectic of (α-Al+Al2Cu+Si) forms. If the growth of the Si phase is suppressed upon the formation of (α-Al+Al2Cu+Si), the growth of both Al and Cu is also suppressed by a cooperative growth mechanism. As a result of analyzing the Al-27wt%Cu-5wt%Si ternary eutectic alloy with a different alloy design simulation programs, it was confirmed that different results arose depending on the program. A computer simulation of the alloy design is a useful tool to reduce the trial and error process in alloy design, but this effort must be accompanied by a task that increases reliability and allows a comparison to microstructural results derived through actual casting.

• Journal of the Korean Chemical Society
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• v.57 no.4
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• pp.483-488
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• 2013

Copper oxide (CuO) was synthesized from $CuCl_2$ by solution method. Anatase $TiO_2$ particle was dispersed into the solution before preparing CuO, so that $TiO_2$/CuO heterojunction was created through the nucleation of CuO onto the $TiO_2$ surface. Some amount of CuO was reduced to $Cu_2O$ by treating glucose into the solution, thereby preparing $TiO_2/Cu_xO$ complex. The obtained $TiO_2/Cu_xO$ complex showed advanced phtocatalytic activity under the sun light compared with the P-25 sample. In addition, the the $TiO_2/Cu_xO$ complex showed excellent antipathogenic effect.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.606-612
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• 1991

We have carried out an extended Huckel calculation to rationalize the role of $CuO_3$ chains and the size effect of the charged model clusters for the following charged model culsters : ${{Cu_6}{O_{21}}^{28-},\;{{Cu_6}{O_{22}}^{30-}\;,{{Cu_9}{O_{30}}^{39-}\;,{{Cu_9}{O_{32}}^{43-}\;,{{Cu_{12}{O_{38}}^{48-}\;,{{Cu_{15}{O_{50}}^{65-}\;,{{Cu_{18}{O_{54}}^{66-}\;,{{Cu_{18}{O_{55}}^{68-}\;,{{Cu_{24}{O_{70}}^{84-}\;and\;{{Cu_{27}{O_{78}}^{93-}$ for high-$T_c$ superconductor $YBa_2Cu_3O_7$: ${{Cu_6}{O_{18}}^{22-}\;,{{Cu_9}{O_{26}}^{31-}}\;,{{Cu_{12}{O_{32}}^{36-}\;,{{Cu_{15}{O_{42}}^{49-}\;,{{Cu_{18}{O_{46}}^{50-}\;,{{Cu_{24}{O_{60}}^{64-}\;and\;{{Cu_{27}{O_{66}}^{69-}$ for insulator $YBa_2Cu_3O_6$. The results show that the electronic structures and properties of the charged model clusters relating to high-$T_c$ superconductor are very sensitive to the size change of the clusters with various environmental effects, wherease those of the charged model clusters for insulator $YBa_2Cu_3O_6$ are monotonous to the size change. The $CuO_3$ chains along the b-direction may yield cooperative electronic coupling with the $CuO_2$ layers in determining both conducting and superconducting properties of $YBa_2Cu_3O_{7-x}$ system.