• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.56-58
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• 2006

본 논문은 PVD(Physical Vapor Deposition)의 마그네트론 스퍼터(Magnetron sputter) 박막코팅(Thin film coating) 공정에서 플라즈마(Plasma)를 발생시키고 제어하는 DC 전원공급 장치에 관한 것이다. 이 논문에서는 임피던스의 변화가 심하고 아크(Arc)가 빈번히 발생하는 플라즈마 부하의 특성에 대해, 과도상태(Transient state)의 출력제어 성능을 향상시키고 아크 발생 시 부하로 전가되는 아크에너지를 저감시키기 위한 직류 전원 공급 장치에 대해 소개한다. 전원장치는 수하특성을 가지며 플라즈마 부하에 적합한 출력 제어성을 확보하고 아크 에너지를 최소화하기 위해 고주파 L-C 직렬공진회로 기법을 적용한다. 개발된 DC 20kW급 전원 장치는 인버터와 고주파 절연변압기, 정류기로 구성된다. 인버터는 $100{\sim}200kHz$의 제어주파수로 PFM 및 PWM 제어를 하며, 단위용량 5kW급 컨버터 4개를 직, 병렬 연결하여 출력리플을 최소화 하였다. 개발된 장치의 우수한 제어성능은 실제 플라즈마 공정에서 시험 평가한 결과를 통해 검증할 수 있었다.

• 한국정밀공학회지
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• 제20권12호
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• pp.126-134
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• 2003

In order to investigate the effect of surface treatment in Aluminium alloy and Titanium alloy which are used to armor material during ballistic impact, a ballistic testing was conducted. Anodizing was used to achieve higher surface hardness of Aluminium alloy and Iron plating in PVD(Physical Vapor Deposition) method was used to achieve higher surface hardness of Titanium alloy. Surface hardness test were conducted using a Micro victor's hardness tester. Ballistic resistance of these materials was measured by protection ballistic limit(V-50), a statical velocity with 50% probability penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed from the results of V-50 test and Projectile Through Plates (PTP) test at velocities greater than V-50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V-50 tests were conducted with 0$^{\circ}$obliquity at room temperature with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration. and penetration modes of surface treated alloy laminates are compared to those of surface non-treated alloy laminates. A high speed photography was used to analyze the dynamic perforation phenomena of the test materials.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.123-123
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• 2011

알루미늄은 경량 금속으로 부식 저항력이 높아 철을 부식으로부터 보호하기 위한 표면처리 소재로 사용되고 있다. 철의 부식을 방지하기 위해서 알루미늄을 코팅하는 경우, 코팅 방법은 용융도금법이 주로 사용되고 있으며, 알루미늄을 빛의 반사막으로 활용하는 경우 진공 중에서 물리기상증착(physical vapor deposition; PVD)법을 사용하기도 한다. 알루미늄 박막을 물리기상 증착으로 코팅하면 박막성장 초기에 핵(nucleus)을 형성하고, 형성된 핵을 중심으로 주상정(column)으로 박막이 성장하는 것이 일반적이다. 알루미늄 박막의 주상정과 주상정 사이에 공극(pore)이 존재하기 때문에 알루미늄 박막을 부식방지 막으로 이용하기 위해서는 두께를 증가시켜야 한다. 본 연구에서는 스퍼터링(unbalanced magnetron sputtering)을 이용하여 치밀한 조직을 갖는 알루미늄 박막을 코팅할 수 있는 공정변수를 도출하고, 치밀한 알루미늄 조직이 철의 부식에 미치는 영향을 평가하였다. 기판은 냉연강판(cold rolled steel sheet)이 사용되었으며, 알루미늄 타겟의 크기는 직경 4 inch이었다. 알루미늄 박막의 미세조직과 밀도에 영향을 주는 공정변수를 확인하기 위해서 스퍼터링 파워, 공정 압력, 외부 자기장 세기 등의 조건을 변화시켜 코팅을 실시하였다. 알루미늄 박막의 밀도 변화에 가장 큰 영향을 준 공정변수는 외부 자기장의 세기와 방향이었다. 알루미늄 박막이 약 3 ${\mu}m$의 두께로 코팅된 냉연강판을 염수분무시험(salt spray test, 5% NaCl)으로 부식특성을 평가한 결과, 시험을 시작한 후 120시간 후에도 적청이 발생하지 않았다. 이러한 결과는 기존의 동일한 두께를 갖는 알루미늄이 코팅된 강판의 내부식 특성의 2배의 성능을 보여준다.

• Corrosion Science and Technology
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• 제12권4호
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• pp.171-178
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• 2013

In a polymer membrane fuel cell stack, the bipolar plate is a key element because it accounts for over 50% of total costs of the stack. In order to lower the cost of bipolar plates, 316L stainless steels coated with nitrides such as TiN and CrN by physical vapor deposition were investigated as alternative materials for the replacement of traditional brittle graphite bipolar-plates. For this purpose, interfacial contact resistances were measured and electrochemical corrosion tests were conducted. The results showed that although both TiN and CrN coatings decreased the interfacial contact resistances to less than $10m{\Omega}{\cdot}cm^2$, they did not significantly improve the corrosion resistance in simulated polymer electrolyte membrane fuel cell environments. A CrN coating on 316L stainless steel showed better corrosion resistance than a TiN coating did, indicating the possibility of using modified CrN coated metallic bipolar plates to replace graphite bipolar plates.

• 한국표면공학회지
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• 제49권6호
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• pp.580-586
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• 2016

Cr-Si-Al-N coating with different Si content were deposited by hybrid physical vapor deposition (PVD) method consisting of unbalanced magnetron (UBM) sputtering and arc ion plating (AIP). The deposition temperature was $300^{\circ}C$, and the gas ratio of $Ar/N_2$ were 9:1. The CrSi alloy and aluminum targets used for arc ion plating and sputtering process, respectively. Si content of the CrSi alloy targets were varied with 1 at%, 5 at%, and 10 at%. The phase analysis, composition and microstructural analysis performed using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) including energy dispersive spectroscopy (EDS), respectively. All of the coatings grown with textured CrN phase (200) plane. The thickness of the Cr-Si-Al-N films were measured about $2{\mu}m$. The friction coefficient and removal rate of films were measured by a ball-on-disk test under 20N load. The friction coefficient of all samples were 0.6 ~ 0.8. Among all of the samples, the removal rate of CrSiAlN (10 at% Si) film shows the lowest values, $4.827{\times}10^{-12}mm^3/Nm$. As increasing of Si contents of the CrSiAlN coatings, the hardness and elastic modulus of CrSiAlN coatings were increased. The morphology and composition of wear track of the films was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy, respectively. The surface energy of the films were obtained by measuring of contact angle of water drop. Among all of the samples, the CrSiAlN (10 at% Si) films shows the highest value of the surface energy, 41 N/m.

• 전기전자학회논문지
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• 제20권4호
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• pp.392-397
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• 2016

본 논문에서는 투명 전극용 ITO(Indium Tin Oxide) 박막의 성막 조건을 알아내기 위하여 DC(Direct Current) 마그네트론 스퍼터를 사용해 증착된 ITO 박막의 특성을 분석하였다. 실험 조건은 1~3[mTorr] 분위기압으로 조절하고 인가전압은 260~330[V]로 10[V]씩 스텝을 주어 실험을 진행하였다. 증착된 박막의 투과율, 굴절률 및 표면과 단면 형상을 자외선-가시광선 분광광도계, 타원편광분석기와 주사전자현미경으로 측정하였다. ITO 성막 조건 1~2[mTorr] 분위기압에서 300[V] 정도의 전압이 투과율이 90[%] 이상으로 우수하고 굴절률이 2이상 이였다. 따라서 높은 투명 전도성 전극을 만들기에 적절한 조건임을 확인하였다.

• 한국표면공학회지
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• 제42권4호
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• pp.179-185
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• 2009

Diamond-like carbon(DLC) films were deposited by linear ion source(LIS)-physical vapor deposition method changing the anode voltages from 800 V to 1800 V, and characteristics of the films were investigated using residual stress tester, nano-indentation, micro raman spectroscopy, scratch tester and Field Emission Scanning Electron Microscope(FE-SEM). The results showed that the residual stress and hardness increased with increasing the ion energy up to anode voltage of 1400 V. It was also found that the content of $SP^3$ carbon increased with increasing the anode voltage $SP^3/SP^2$ ratio through investigation of $SP^3/SP^2$ ratio by the micro-raman analysis. From these results, it can be concluded that the physical properties of DLC films such as residual stress and hardness are increased with increasing the anode voltage. These results can be explained that 3-dimensional cross-links between carbon atoms and Dangling bond are enhanced and the internal compressive stress also increased with increasing the anode voltage. The optimal anode voltage is considered to be around 1400 V in these experimental conditions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.375-375
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• 2010

CdTe as an absorber material is widely used in thin film solar cells with the heterostructure due to its almost ideal band gap energy of 1.45 eV, high photovoltaic conversion efficiency, low cost and stable performance. The deposition methods and preparation conditions for the fabrication of CdTe are very important for the achievement of high solar cell conversion efficiency. There are some rearranged reports about the deposition methods available for the preparation of CdTe thin films such as close spaced sublimation (CSS), physical vapor deposition (PVD), vacuum evaporation, vapor transport deposition (VTD), closed space vapor transport, electrodeposition, screen printing, spray pyrolysis, metalorganic chemical vapor deposition (MOCVD), and RF sputtering. The RF sputtering method for the preparation of CdTe thin films has important advantages in that the thin films can be prepared at low growth temperatures with large-area deposition suitable for mass-production. The authors reported that the optical and electrical properties of CdTe thin film were closely connected by the thickness-uniformity of the film in the previous study [1], which means that the better optical absorbance and the higher carrier concentration could be obtained in the better condition of thickness-uniformity for CdTe thin film. The thickness-uniformity could be controlled and improved by the some process parameters such as vacuum level and RF power in the sputtering process of CdTe thin films. However, there is a limitation to improve the thickness-uniformity only in the preparation process [1]. So it is necessary to introduce the external or additional method for improving the thickness-uniformity of CdTe thin film because the cell size of thin film solar cell will be enlarged. Therefore, the authors firstly applied the chemical mechanical polishing (CMP) process to improving the thickness-uniformity of CdTe thin films with a G&P POLI-450 CMP polisher [2]. CMP process is the most important process in semiconductor manufacturing processes in order to planarize the surface of the wafer even over 300 mm and to form the copper interconnects with damascene process. Some important CMP characteristics for CdTe were obtained including removal rate (RR), WIWNU%, RMS roughness, and peak-to-valley roughness [2]. With these important results, the CMP process for CdTe thin films was performed to improve the thickness-uniformity of the sputtering-deposited CdTe thin film which had the worst two thickness-uniformities of them. Some optical properties including optical transmittance and absorbance of the CdTe thin films were measured by using a UV-Visible spectrophotometer (Varian Techtron, Cary500scan) in the range of 400 - 800 nm. After CMP process, the thickness-uniformities became better than that of the best condition in the previous sputtering process of CdTe thin films. Consequently, the optical properties were directly affected by the thickness-uniformity of CdTe thin film. The absorbance of CdTe thin films was improved although the thickness of CdTe thin film was not changed.

• International Journal of Control, Automation, and Systems
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• 제4권6호
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• pp.748-755
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• 2006

In this paper, a trade-off design and fabrication of IPMC(Ionic Polymer Metal Composites) as an actuator for a flapping device have been described. Experiments for the internal solvent loss of IPMCs have been conducted for various combinations of cation and solvent in order to find out the best combination of cation and solvent for minimal solvent loss and higher actuation force. From the experiments, it was found that IPMCs with heavy water as their solvent could operate longer. Relations between length/thickness and tip force of IPMCs were also quantitatively identified for the actuator design from the tip force measurement of 200, 400, 640, and $800{\mu}m$ thick IPMCs. All IPMCs thicker than $200{\mu}m$ were processed by casting $Nafion^{TM}$ solution. The shorter and thicker IPMCs tended to generate higher actuation force but lower actuation displacement. To improve surface conductivity and to minimize solvent evaporation due to electrically heated electrodes, gold was sputtered on both surfaces of the cast IPMCs by the Physical Vapor Deposition(PVD) process. For amplification of a short IPMC's small actuation displacement to a large flapping motion, a rack-and-pinion type hinge was used in the flapping device. An insect wing was attached to the IPMC flapping mechanism for its flapping test. In this test, the wing flapping device using the $800{\mu}m$ thick IPMC. could create around $10^{\circ}{\sim}85^{\circ}$ flapping angles and $0.5{\sim}15Hz$ flapping frequencies by applying $3{\sim|}4V$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.388-389
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• 2005

In this paper, the electric properties of mercury Iodide multi-layer samples has been investigated. We measured and analyzed their performance parameters such as the X-ray sensitivity and dark-current for a mercury Iodide multi-layer X-ray detector with a dielectric layer. The digital X-ray image detector can be constructed by integrating photoconduction multi-layer that dielectric layer has characteristics of low dark-current, high X-ray sensitivity. However this process has found to have complexity on the performance of the sample. We have investigate dielectric layer that it substitute dielectric layer for HgO(Mercury Oxide). We have employed two approaches for producing the mercury Iodide sample : 1) Physical Vapor Deposition(PVD) and 2) Particle-In-Binder(PIB). In this paper fabricated by PIB Method with thicknesses ranging from approximately 180um to 240um and we could produce high-quality samples for each technique particular application. As results, the dielectric materials such as HgO between the dielectric layer and the top electrode may reduce the dark-current of the samples. Mercury Iodide multi-layer having HgO has characteristics of low dark-current, high X-ray sensitivity and simple processing. So we can acquired a enhanced signal to noise ratio. In this paper offer the method can reduce the dark-current in the X-ray detector.