• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.709-716
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• 1999

Ceramic is select for an alternative substrate material for high-speed circuits due to its low-thermal expansion. As, in this study, ceramic was prepared by ISG (interlayer sol-gel) process using metal salts and a metal alkoxide as the starting materials. Generally ceramic substrate is used electroless copper plating for the metallization. But it has been indicate weakely the adhesion strength between the substrate and copper layer. Therefore, this research, using the ISG process on the preparation of homogeneous and possible preparation at law temperature fabricated sol solution. Using of the dip coating method was coated for the purpose of giving the anchoring effect on the coating layer and enhancing the adhesion strength between the $Al_2$O$_3$ substrate and copper layer. This study examined primary the characteristic of the sol making condition and differential thermal analysis (DTA) X-ray diffraction (XRD) were mearsured to identify the crystal phase of heat treatment specimens. The morphology of the coated films were studied by scanning electron microscopy(SEM). As a resurt, XRD analysis was obtained patterns of $\alpha$-cordierite after heat-treatment about 2 hours at $1000^{\circ}C$. SEM analysis could have seen a large number of voids on coated film. The more contants of$ Al_2$$O_3$ Wt% was increased the more voids was advanced. Peel adhesion strength has a maximum in the contants of the TEOS:ANE of 1:0.7 mole%. In this case, adhesion strength has been measured 1150gf, peel adhesion strength were about 10 times more than uncoated of the ceramics film.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1600-1604
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• 2017

Mo-Cu alloys have been widely used for heat sink materials, vacuum technology, automobile and many other applications due to their excellent physical and electronic properties. Especially, Mo-Cu composites with 5~20 wt% copper are widely used for the heavy duty service contacts due to their excellent properties like low coefficient of thermal expansion, wear resistance, high temperature strength and prominent electrical and thermal conductivity. In most of the applications, high dense Mo-Cu materials with homogeneous microstructure are required for high performance, which has led in turn to attempts to prepare ultra-fine and well-dispersed Mo-Cu powders in different ways, such as spray drying and reduction process, electroless plating technique, mechanical alloying process and gelatification-reduction process. However, most of these methods were accomplished at high temperature (typically degree), resulting in undesirable growth of large Cu phases; furthermore, these methods usually require complicated experimental facilities and procedure. In this study, Mo-Cu alloying were prepared by planetary ball milling (PBM) and spark plasma sintering (SPS) and the effect of Cu with contents of 5~20 wt% on the microstructure and properties of Mo-Cu alloy has been investigated.

• Current Applied Physics
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• v.18 no.11
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• pp.1235-1239
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• 2018

We present a novel process to fabricate three-dimensional (3D) metallic patterns from 3D printed polymeric structures utilizing different hygroscopic swelling behavior of two different polymeric materials. 3D patterns are printed with two different polymers as cube shape. The surface of the 3D printed polymeric structures is plated with nickel by an electroless plating method. The nickel patterns on the surface of the 3D printed cube shape structure are formed by removing sacrificial layers using the difference in the rate of hygroscopic swelling between two printing polymer materials. The hygroscopic behavior on the interfaced structure was modeled with COMSOL Multiphysics. The surface and electrical properties of the fabricated three-dimensional patterns were analyzed and characterized.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.24-27
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• 2023

Until now, many research activities have been conducted to commercialize high-temperature superconducting (HTS) wires for electric applications. Most of all researchers have focused on enhancing the piece length, critical current density, mechanical strength, and throughput of HTS wires. Recently, HTS magnet for generating high magnetic field shows degraded performance due to the deformation of HTS wire by high electro-magnetic force. The deformation can be derived from widthwise thickness non-uniformity of HTS wire mainly caused by wet processes such as electro-polishing of metal substrate and electro-plating of copper. Gradient sputtering process is designed to improve the thickness uniformity of HTS wire along the width direction. Copper stabilizing layer is deposited on HTS wire covered with specially designed mask. In order to evaluate the thickness uniformity of HTS wire after gradient sputtering process, the thickness distribution across the width is measured by using the optical microscope. The results show that the gradient deposition process is an effective method for improving the thickness uniformity of HTS wire.

• Journal of Korea Foundry Society
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• v.25 no.6
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• pp.259-264
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• 2005

The copper clad steel wire is used extensively as lead wires of electronic components such as capacitors, diodes and glass sealing lamp because the wire combines the strength and low thermal expansion characteristic of Fe-Ni steel with the conductivity and corrosion resistance of copper. In order to fabricate the copper clad steel wire, several processes including electro-plating, tubecladding extrusion process and dip forming process have been introduced and applied. The electroplating process for the production of copper clad steel wire shows poor productivity and induces environmental load generation such as electroplating solution. The dip forming process is suitable to mass production of copper clad steel such as trolley wire. and need expensive manufacturing facilities. The present paper describes the improvement of the conventional continuous casting process to fabricate copper clad steel wire, which its core metal is low thermal expansion Fe-Ni alloy and its sheath material is copper. In particular, the formation of intermetallic compound at interface between core and sheath was investigated in order to introduce optimum continuous casting process parameter for fabrication of copper clad steel wire with higher electrical conductivity. The mechanical strength of copper clad steel wire was also investigated through wiredrawing process with of 95% in total reduction ratio.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1375-1381
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• 2018

In this paper, we studied coatings of the DLC thin film for improving loosening torque of dental implant screw. We used a filtered arc ion plating process which can realize the most dense DLC layer by coating the DLC thin film on the surface of the dental abutment screw. It showed both hardness comparable to diamond and low friction coefficient similar to graphite, and to improve the loosening phenomenon by increasing the screw tightening force Cr/CrN, Ti/TiN or Ti/TiN/Cr/CrN buffer layers were deposited for 5 to 10 minutes to improve the adhesion of the DLC thin film to the surface of the Ti (Gr.5), and then the DLC thin film was coated for about 15 minutes. As a result, the Cr/CrN buffer layer exhibited the highest hardness of 29.7 GPa, the adhesion of 18.62N on average, and a very low coefficient of friction of less than 0.2 as a whole. And we measured loosening torque after one million times with masticatory movement simulator. As a result, the values of the coated screw loosening torque were clearly higher than those of the uncoated screw. From this, it was found that the DLC coating was effective methods improving the loosening torque. In addition, it was confirmed that the cytotoxicity test and cell adhesion test showed high biocompatibility.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.3-13
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• 1993

This study was conducted at seven degreasing processes in plating plants located in Seoul, Incheon, Ansan, and Taejeon areas from July 21 to august 27, 1992. This study was performed to assess the TWA exposures to trichloroethylene (TCE) and evaluate factors affecting TCE concentrations in degreasing process. Two-Point Eddy Diffusional Model suggested by Wadden et al. was employed to calculalte emission factors according to degreaser type. Results are summarized as follows. 1. The TWA exposures of the degreasing operators ranged from 1.4 ppm to 123 ppm, and those of three plants out of seven were exceeding 50 ppm of both the Korean and U.S. OSHA standards. Degreasing assistant of Plant B, was exposed to 59 ppm. 2. The average concentrations at the distance 0, 1.5, 3.0 m from the degreasers were 1.014, 24, and 18 ppm, respectively, and showed a signifficant difference by distance (p<0.01). 3. The emission of TCE was reduced by installing local exhaust systems, condensers, and refrigeration lines at the degreasers (p<0.01). 4. The major factors related to exposure of operators were workload (r=.9621. p<0.01) and dimensions of degreansing room(r=-.8667, p<0.05). 5. If the air in degreasing room is mixed violently by other factors in addition to diffusion, the emission factors can not be evaluated because the important hypothesis of the Two-Point Eddy Diffusional Model can not be accepted. 6. The ultrasonic degreaser without the local exhaust ststem, condenser, and refrigeration lines emitted TCE three times greater than the ultrasonic degreaser with condenser and refrigeration 1ines only.

• Journal of Yeungnam Medical Science
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• v.10 no.1
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• pp.212-217
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• 1993

Since discovery of X-rays, radiotherapy has evolved into one of the most scientific branches of medicine and has established its role as the primary line or the secondary line of attack, after surgery, in the treatment of malignant cancers. Nowadays its importance is illustrated by the fact that as many as 70 per cent of all pastients with cancer will receive radiation therapy at sometime during their disease process. Biologic effects of X-rays began to be apparant soon after the discovery by Roentgen in 1895. In clinical radiotherapy, the biologic endpoint of most importance is loss of cellular reproductive ability or clonogenicity. One of the commonest ways to assess cell survival is to use an in vitro plating assay. We analyzed radiation effect on colony formation of HaLa.S3(SC) cell line and obtained results are as follows: The plating efficiency is 0.464. The shape of cell survival curve is similar to multi-target plus single hit component model. Estimated values of Do, Dq, and extrapolation number are 150 cGy, 80 cGy and 1.7 respectively. We reported these experimental data with review of literature.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.55-59
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• 2012

Defects such as voids or seams are frequently found in TSV via filling process. To achieve defect-free copper via filling, organic additives such as suppressor, accelerator and leveler were necessary in a copper plating bath. However, by-products stemming from the breakdown of these organic additives reduce the lifetime of the devices and plating solutions. In this research, the effects of levelers on copper electrodeposition were investigated without suppressor and accelerator to lower the concentration of additives. Threelevelers(janus green B, methylene violet, diazine black) were investigated to study the effects of levelers on copper deposition. Electrochemical behaviors of these levelers were different in terms of deposition rate. Filling performances were analyzed by cross sectional images and its characteristics were different with variations of levelers.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.95-99
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• 2005

Quaternary Ti-Cr-Si-N coatings were synthesized onto steel substrates (SKD 11) using a hybrid method of arc ion plating (AIP) and sputtering techniques. For the Syntheses of Ti-Cr-Si-N coatings, the Ti-Cr-N coating process was performed substantially by a multi-cathodic AIP technique rising Cr and Ti targets, and Si was added by sputtering Si target during Ti-Cr-N deposition. In this work, comparative studies on microstructure and evaluation of mechanical properties between Ti-Cr-N and Ti-Cr-Si-N coatings were conducted. As the Si was incorporated into Ti-Cr-N coatings, the Ti-Cr-Si-N coatings showed largely increased hardness value of approximately 42 GPa than one of 28 GPa for Ti-Cr-N coatings. The average friction coefficient of Ti-Cr-N coatings largely decreased from 0.7 to 0.35 with increasing Si content up to 20 at. $\%$. In addition, wear behavior of Ti-Cr-N coatings against steel ball was much improved with Si addition due to the surface smoothening effect and tribe-chemical reaction.