• Journal of the Korean institute of surface engineering
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• v.50 no.3
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• pp.164-169
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• 2017

Ni-Cr-X ternary interlayers were investigated to improve the adhesion of Cu/Ni-Cr/Polyimide flexible copper clad laminates. The ternary compounds are sputtered Ni-Cr-X films (where X is one of Nb, V, Mo, or Ti), and the effect of third elements on the adhesion was evaluated and investigated chemically and mechanically. The feel strength was higher in the order of Ni-Cr-Nb > Ni-Cr-V > Ni-Cr > Ni-Cr-Mo > Ni-Cr-Ti. Nb, which has a comparable standard electrode potential to Cr, increased the adhesion, while Ti, with a low standard electrode potential, degraded the adhesion. The Ni-Cr-Nb interlayer was amorphous, while Ni-Cr-Ti was partially crystalline. The similar morphology structure of the Ni-Cr-Nb interlayer with polyimide resulted in a better adhesion.

• Journal of the Korean Applied Science and Technology
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• v.16 no.4
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• pp.307-311
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• 1999

Interfacial properties of electrode and organic thin layer is one of the most important factor in performing a Light Emitting Diodes(LED). Phthalocyanine copper was used as a buffer layer to improve interface characteristic, so that device efficiency was improved. In this study, LEDs were fabricated as like structures of Indium-Tin-Oxide (ITO) / N,N' -Diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) / 8-Hydroxyquinoline aluminum(Alq) / Aluminum(Al) and Indium-Tin-Oxide(ITO) / N,N'-Diphenyl-N,N' -di(m-tolyl)-benzidine(TPD) / 2-(4-Biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole(PBD) / Aluminum(Al). In these devices, CuPC was layered at electrode/organic layer interface. As position is changing and thickness is changing, devices showed characteristic luminescence efficiency and luminescence inensity respectively. We showed in this study that luminescence efficiency was improved with CuPC layer in LEDs. The efficiency of device with layer CuPC is higher than that of 2 layer CuPC. However, the luminescence of 2 layer CuPC device got higher value.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.785-791
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• 2023

Copper sulfide (Cu_xS) has been extensively utilized as a counter electrode (CE) material for quantum dot solar cells (QDSCs) due to its exceptional catalytic activity for polysulfide electrolytes. The typical fabrication method of Cu₂S CEs based on brass substrate is dangerous, involving the use of a highly concentrated hydrochloric acid solution in a relatively high temperature. In contrast, electroplating presents a safer alternative by employing a less acidic solution at a room temperature. In addition, the electroplating method increases the probability of obtaining CEs of consistent quality compared to the brass method. In this study, the optimized electroplating cycle for CuS CEs in QDSCs has been studied for the highly efficient photovoltaic performances. The QDSCs, featuring electroplated CuS CEs, achieved an impressive efficiency of 7.18%, surpassing the conventional method employing brass CEs, which yielded an efficiency of 6.62%.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.73-77
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• 2017

Recently, fingerprint sensors have widely used for personal information security, and require quality evaluation to reduce an error of their recognition rate. Quality of fingerprint sensors is evaluated by variation of their electrical resistance introducing by contacts between a probe tip and a sensor electrode, Investigation on the materials compatability and structure optimization of probe is required to reduce deformation of sensor electrode for repeatability of quality testing. Nickel, steel(SK4), beryllium copper, and phosphor bronze were considered as probe materials, and beryllium copper was the most appropriate for materials of probe tips, considering indentation and contact resistance while being contacted probe tips on electrodes. Probes of an inspection part were manufactured with the single-unit structure for physical damage prevention and parallel processing capability. Inspection repeatability was evaluated by voltage variation of fingerprint sensors when the specific current was applied. A single-unit inspection part with beryllium copper probe tips showed excellent repeatability within ${\pm}0.003V$ of its voltage variation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.8
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• pp.99-109
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• 2022

In this study, an electric resistance-heated surface friction spot-welding process was proposed and tested for the spot-welding ability of copper and aluminum dissimilar metal sheets using electric resistance heating and surface friction heating. This process has welding variables, such as the current value, energizing cycles, rotational speed, and friction time. The current value and energizing cycle can affect the resistance heat, and the rotational speed of the rotating pin and friction time influence frictional heat generation. Resistance heating before friction heating has a preheating effect on the Cu-Al contact interface and a positive effect on preventing friction heat loss during the friction stage. However, because resistance preheating can soften the copper sheet and affect the contact stress and friction coefficient, it has difficulties that may adversely affect frictional heat generation. Therefore, the optimal combination of welding variables should be determined through simulations and experiments of the spot-welding process to determine the effects of electric resistance preheating on the suggested process. Through this procedure, it is known that the proposed spot-welding process can improve the welding quality during the spot welding of Cu-Al sheets.

• Clean Technology
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• v.18 no.2
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• pp.183-190
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• 2012

Electrochemical regeneration of the iron chloride waste solution from PCB etching reduces environmental contamination and produces copper as by-product, so the economic feasibility is high. But iron chloride waste solution contains iron and copper and the reactions occurring in the electrolytic cell are complicated. In this work, the oxidation of iron chloride and copper deposition were examined through batch electrolysis and the optimum conditions of the process parameters were found. The oxidation of ferrous chloride was achieved easily to the desired level. The copper deposition efficiency was high in the reaction using the carbon cathode when the copper density was 12 g/L with the electric current density of $350mA/cm^2$, and the ratio of the $Fe^{2+}$ ion was high. In addition, the possibility of the scale-up was confirmed in continuous operation of bench reactor using the optimum conditions obtained.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.249-255
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• 2021

In this work, we proposed a facile method to fabricate the three-dimensional porous copper current collector (3D Cu CC) for a Si-dominant anode in a Li-ion battery (LiB). The 3D Cu CC was prepared by combining chemical etching and thermal reduction from a planar copper foil. It had a porous layer employing micro-sized Cu balls with a large surface area. In particular, it had strengthened attachment of Si-dominant active material on the CC compared to a planar 2D copper foil. Moreover, the increased contact area between a Si-dominant active material and the 3D Cu could minimize contact loss of active materials from a CC. As a result of a battery test, Si-dominant active materials on 3D Cu showed higher cyclic performance and rate-capability than those on a conventional planar copper foil. Specifically, the Si electrode employing 3D Cu exhibited an areal capacity of 0.9 mAh cm^-2 at the 300^th cycles (@ 1.0 mA cm^-2), which was 5.6 times higher than that on the 2D copper foil (0.16 mAh cm^-2).

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.21-27
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• 2011

A nano-porous structure of tin oxide was prepared using an anodic oxidation process and the sample's electrochemical properties were evaluated for application as an anode in a rechargeable lithium battery. Microscopic images of the as-anodized sample indicated that it has a nano-porous structure with an average pore size of several tens of nanometers and a pore wall size of about 10 nanometers; the structural/compositional analyses proved that it is amorphous stannous oxide (SnO). The powder form of the as-anodized specimen was satisfactorily lithiated and delithiated as the anode in a lithium battery. Furthermore, it showed high initial reversible capacity and superior rate performance when compared to previous fabrication attempts. Its excellent electrode performance is probably due to the effective alleviation of strain arising from a cycling-induced large volume change and the short diffusion length of lithium through the nano-structured sample. To further enhance the rate performance, the attempt was made to create porous tin oxide film on copper substrate by anodizing the electrodeposited tin. Nevertheless, the full anodization of tin film on a copper substrate led to the mechanical disintegration of the anodic tin oxide, due most likely to the vigorous gas evolution and the surface oxidation of copper substrate. The adhesion of anodic tin oxide to the substrate, together with the initial reversibility and cycling stability, needs to be further improved for its application to high-power electrode materials in lithium batteries.

• Korean Journal of Materials Research
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• v.29 no.1
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• pp.37-42
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• 2019

This study investigates Ag coated $Cu_2O$ nanoparticles that are produced with a changing molar ratio of Ag and $Cu_2O$. The results of XRD analysis reveal that each nanoparticle has a diffraction pattern peculiar to Ag and $Cu_2O$ determination, and SEM image analysis confirms that Ag is partially coated on the surface of $Cu_2O$ nanoparticles. The conductive paste with Ag coated $Cu_2O$ nanoparticles approaches the specific resistance of $6.4{\Omega}{\cdot}cm$ for silver paste(SP) as $(Ag)/(Cu_2O)$ the molar ratio increases. The paste(containing 70 % content and average a 100 nm particle size for the silver nanoparticles) for commercial use for mounting with a fine line width of $100{\mu}m$ or less has a surface resistance of 5 to $20{\mu}{\Omega}{\cdot}cm$, while in this research an Ag coated $Cu_2O$ paste has a larger surface resistance, which is disadvantageous. Its performance deteriorates as a material required for application of a fine line width electrode for a touch panel. A touch panel module that utilizes a nano imprinting technique of $10{\mu}m$ or less is expected to be used as an electrode material for electric and electronic parts where large precision(mounting with fine line width) is not required.

• Resources Recycling
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• v.31 no.5
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• pp.59-66
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• 2022

To investigate the rate-determining step of nickel, cobalt and copper electrowinning, experiments were conducted by varying the electrolyte temperature and agitation speed using a rotating disc electrode. Analyzing the rate-determining step by calculating the activation energy in the electrowinning process, it was found that nickel electrowinning is controlled by a mixed mechanism (partly by chemical reaction and partly by mass transport), cobalt is controlled by chemical reaction, and copper is controlled by mass transfer. Electrowinning of nickel, cobalt and copper was performed by varying the electrolyte temperature and agitation speed, and the comparison of the current efficiencies was used the determine the rate-determining step.