• 한국표면공학회지
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• 제36권3호
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• pp.242-250
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• 2003

Electrodeposition of Ni was carried out on copper substrate from Ni Sulfamate bath by DC and high frequency pulse current. During the electroplating, bath temperature was steady $60^{\circ}C$ , agitation was applied. Morphology and surface roughness of electrodeposits was investigated with the AFM. Crystalline structure of electrodeposits was investigated with XRD. Also, surface electric resistivity was investigated with 4-point probe. The result of crystalline structure by X-ray diffractometer, in the case of DC, <200> direction was dominant growing direction. But in the case of PC, the ratio of <200> direction vs. other direction decreased. As the pulse frequency increased, the enhanced properties of deposits were shown. With increasing frequency, the degree of surface properties increased DC more than that of PC, eg surface morphology, roughness and the degree of compactness of grains. With increasing duty cycle, the surface properties such as the degree of the morphology, roughness and electroconductivity was deteriorated.

• 마이크로전자및패키징학회지
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• 제13권4호
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• pp.57-63
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• 2006

칩 스택 패키지의 삼차원 interconnection에 적용을 위해 폭 $75{\sim}10\;{\mu}m$, 길이 3mm의 트랜치 비아에 대해 전기도금전류밀도 및 전류모드에 따른 Cu filling 특성을 분석하였다. 직류모드로 $1.25mA/cm^{2}$에서 Cu filling한 경우, 트랜치 비아의 폭이 $75{\sim}35{\mu}m$ 범위에서는 95% 이상의 높은 Cu filling ratio를 나타내었다. 직류 전류밀도 $2.5mA/cm^{2}$에서 Cu filling한 경우에는 $1.25mA/cm^{2}$ 조건에 비해 열등한 Cu filling ratio를 나타내었으며, 직류모드에 비해 펄스모드가 우수한 Cu filling 특성을 나타내었다.

• 마이크로전자및패키징학회지
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• 제13권4호
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• pp.37-43
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• 2006

플립칩 공정에 Sn 범프를 적용하기 위해 도금전류밀도와 전류모드에 따른 Sn 도금막의 표면 거칠기와 경도를 측정하였다. 전류밀도 $5{\sim}50\;ma/cm^{2}$에서 전기도금한 Sn 도금막은 $2.0{\sim}2.4{\mu}m$의 표면 거칠기를 나타내었으며, 직류모드보다 펄스모드로 형성한 Sn 도금막에서 표면 거칠기가 감소하였다 할로겐 램프를 사용하여 $300^{\circ}C$에서 3초간 유지하는 표면 열처리에 의해 Sn 도금의 표면 거칠기가 $1\;{\mu}m$ 정도로 현저히 저하되었다. 전류밀도 $5{\sim}50mA/cm^{2}$에서 전기도금한 Sn 도금막은 10 Hv의 경도를 나타내었다. Sn 범프들을 이용하여 플립칩 본딩한 시편들은 $33{\sim}17m{\Omega}$의 낮은 접속저항을 나타내었다.

• 마이크로전자및패키징학회지
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• 제13권4호
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• pp.45-50
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• 2006

3D package의 SiP에서 구리의 via filling은 매우 중요한 사항으로 package밀도가 높아짐에 따라 via의 크기가 줄어들며 전기도금법을 이용한 via filling이 연구되어왔다. Via filling시 via 내부에 결함이 발생하기 쉬운데 전해액 내에 억제제, 가속제등 첨가제를 첨가하고 펄스-역펄스(PRC)의 전류파형을 인가하여 결함이 없는 via의 filling이 가능하다. 본 연구에서는 건식 식각 방법 중 하나인 DRIE법을 이용하여 깊이 $100{\sim}190\;{\mu}m$, 직경이 각각 $50{\mu}m,\;20{\mu}m$인 2가지 형태의 via을 형성하였다. DRIE로 via가 형성된 Si wafer위에 IMP System으로 Cu의 Si으로 확산을 막기 위한 Ta층과 전해도금의 씨앗층인 Cu층을 형성하였다. Via시편은 직류, 펄스-역펄스의 전류 파형과 억제제, 가속제, 억제제의 첨가제를 모두 사용하여 filling을 시도하였고, 공정 후 via의 단면을 경면 가공하여 SEM으로 관찰하였다.

• 사물인터넷융복합논문지
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• 제9권3호
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• pp.61-67
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• 2023

구리의 전기주조 공정을 최적화하기 위하여 이중 비밀 다층구조의 역전파 뉴럴 네트워크가 구성된다. 샘플 학습을 통하여, 구리 전기주조 공정 조건과 목표 특성 간의 함수관계가 정확히 성취되고, 구리 전기주조 공정 내에서 다층구조의 미세강도와 장력에 대한 예측이 이루어진다. 예측된 결과는 펄스 전원공급기를 장착한 구리 피로인산염 솔루션 시스템 내에서 구리의 전해석출 시험에 의하여 증명된다. 그 결과는 다음과 같이 나타난다. "3-4-3-2" 구조의 이중비밀 다층구조 뉴럴 네트워크에 의하여 예측된 구리 다층구조의 미세강도와 장력은 실험값에 매우 근접하며 그 상대적 오차는 2.32%보다 작다. 주어진 파라미터의 범위 내에서, 구리의 미세강도는 100.3~205.6MPa이며, 장력은 112~485MPa 정도로 측정된다. 미세강도와 장력이 최적인 조건에서 그에 대응하는 공정 조건은 다음과 같다: 전류밀도는 2A·dm-2, 펄스 주파수는 2KHz, 펄스의 듀티싸이클은 10%이다.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1755-1762
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• 2013

A graphene-Zn/Al layered double hydroxide composite film was simultaneously prepared by electrochemical deposition on the surface of a glassy carbon electrode (G-LDH/GCE) from the mixture solution containing GO and nitrate salts of $Zn^{2+}$ and $Al^{3+}$. The modified electrode showed good electrochemical performances toward the simultaneous electrochemical detection of hydroquinone (HQ), catechol (CA) and resorcinol (RE) due to the unique properties of graphene (G) and LDH such as large active surface area, facile electronic transport and high electrocatalytic activity. The redox characteristics of G-LDH/GCE were investigated with cyclic voltammetry and differential pulse voltammetry. The well-separated oxidation peak potentials, corresponding to the oxidation of HQ, CA and RE, were observed at 0.126 V, 0.228 V and 0.620 V respectively. The amperometric response of the modified electrode exhibited that HQ can be detected without interference of CA and RE. Under the optimized conditions, the oxidation peak current of HQ is linear with the concentration of HQ from 6.0 ${\mu}M$ to 325.0 ${\mu}M$ with the detection limit of 0.077 ${\mu}M$ (S/N=3). The modified electrode was successfully applied to the direct determination of HQ in a local tap water, showing reliable recovery data.

• 한국표면공학회지
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• 제53권4호
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• pp.138-143
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• 2020

In this study, we produced a coil of micro-pattern that can be used for electromagnetic wave absorber, heating material, wireless charging, sensor, antenna, etc. by using electrochemical additive manufacturing method. Currently, it contains research contents for manufacturing a micro pattern coil having practicality through control of process control variables such as applied voltage, distance between electrode, and nozzle injection. Circulation of the electrolyte through the nozzle injection control can significantly contribute to improving the surface characteristics of the coil because of minimizing voltage fluctuations that may occur during the additive manufacturing process. In addition, by applying the pulse method in the application of voltage, the lamination characteristics of the plated body were improved, which showed that the formation of a fine line width plays an important role in the production of a micro pattern coil. By applying the pulse signal to the voltage application, the additive manufacturing characteristics of the produced product were improved, and it was shown that the formation of a fine line width plays an important role in the production of a micro pattern coil.

• Nano
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• 제13권11호
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• pp.1850131.1-1850131.19
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• 2018

In this paper, an electrochemical sensor for epinephrine (EP), a neurotransmitter was developed by anchoring molecularly imprinted polymeric matrix (MIP) on the surface of gold-coated quartz crystal electrode of electrochemical quartz crystal microbalance (EQCM) using starch nanoparticles (Starch NP) - reduced graphene oxide (RGO) nanocomposite as polymeric format for the first time. Use of EP in therapeutic treatment requires proper dose and route of administration. Proper follow-up of neurological disorders and timely diagnosis of them has been found to depend on EP level. The MIP sensor was developed by electrodeposition of starch NP-RGO composite on EQCM electrode in presence of template EP. As the imprinted sites are located on the surface, high specific surface area enables good accessibility and high binding affinity to template molecule. Differential pulse voltammetry (DPV) and piezoelectrogravimmetry were used for monitoring binding/release, rebinding of template to imprinted cavities. MIP-coated EQCM electrode were characterized by contact angle measurements, AFM images, piezoelectric responses including viscoelasticity of imprinted films, and other voltammetric measurements including direct (DPV) and indirect (using a redox probe) measurements. Selectivity was assessed by imprinting factor (IF) as high as 3.26 (DPV) and 3.88 (EQCM). Sensor was rigorously checked for selectivity in presence of other structurally close analogues, real matrix (blood plasma), reproducibility, repeatability, etc. Under optimized conditions, the EQCM-MIP sensor showed linear dynamic ranges ($1-10{\mu}M$). The limit of detection 40 ppb (DPV) and 290 ppb (EQCM) was achieved without any cross reactivity and matrix effect indicating high sensitivity and selectivity for EP. Hence, an eco-friendly MIP-sensor with high sensitivity and good selectivity was fabricated which could be applied in "real" matrices in a facile manner.

• Corrosion Science and Technology
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• 제5권5호
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• pp.168-172
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• 2006

Alloy 600 having a superior resistance to a corrosion is used as a steam generator tubing in nuclear power plants. In spite of its high corrosion resistance, there are many tubings which experience corrosion problems such as a SCC under the high temperature and high pressure environments of nuclear power plants. The Alloy 600 tubing can be repaired by using a Ni electroplating having an excellent SCC resistance. In order to carry out a successful Ni electrodeposition inside a steam generator tubing, the effects of various parameters on the material properties of the electrodeposit should be elucidated. Hence this work deals with the effects of an applied current density, duty cycle($T_{on}/(T_{on}+T_{off})$) of a pulse current, bath temperature and solution pH on the material properties of Ni electrodeposit obtained from a Ni sulphamate bath by analyzing the current efficiency, potentiodynamic curve, hardness and stress-strain curve. Hardness, YS(yield strength) and TS(tensile strength) decreased whereas the elongation increased as the applied current density increased. This was thought to be by a concentration depletion at the interface of the electrodeposit/solution, and a fractional decrease of the hydrogen reduction reaction. As the duty cycle increased, the hardness, YS and TS decreased while the elongation increased. During an off time at a high duty cycle, the concentration depletion could not be recovered sufficiently enough to induce a coarse grain sized electrodeposit. With an increase of the solution temperature and pH, the YS and TS increased while the elongation decreased. The experimental results of the hardness and the stress-strain curves can be supplemented by the results of the potentiodynamic curve.

• 에너지공학
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• 제5권2호
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• pp.108-114
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• 1996

태양열 집열판의 효율을 증대시키기 위하여는 집열판에 조사되는 태양광의 흡수율을 높이고 복사에 의한 열손실을 감소시키는 선택적 박막을 집열판에 입히는 것이 중요한 인자이다. 본 실험에서는 이와같은 광학적 특성을 지니게 하고 동시에 전류효율이 우수한 pulsecurrent 전해법을 도입하여 실제 실용화 규모인 230 cm$\times$60 크기의 대형 기판에 선택흡수박막의 전착을 실시하였다. 도금액의 조성은 크롬산 280 g/$\ell$, propionic acid 15g/$\ell$, 그리고 제 2첨가제10g/$\ell$이었으며, 도금 대상기판으로는 구리와 알루미늄이 사용되었다. 구리 기판의 경우에는 선택흡수박막의 흡수율이 약 0.98이고 복사율은 약 0.17의 광학적 성질을 보였으며, 30$0^{\circ}C$공기 중에서 24시간동안 열처리 후에도 광학적 우수성을 지니고 있어 상품적 가치가 매우 우수하다고 판단되었다. 알루미늄 기판의 경우에는 흡수율이 약 0.97, 복사율이 0.15로서 광학적 성질은 구리 기판에 비해 다소 떨어지지만, 열전도도와 경제성을 고려하면 상품적 가치가 충분하다고 생각된다. 또한 이와 같은 대형기판을 적용하여 안정된 태양광 선택흡수박막의 성공적 제조로 공정의 단순화 및 대량생산 기술을 확보하였으며, 상용화에 돌입하게 되었다.