• 마이크로전자및패키징학회지
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• 제8권3호
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• pp.19-24
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• 2001

반도체 패키지에 사용되는 주요 재료인 리드프레임은 반도체 제품의 소형화, 박형화, 고집적 화에 대응하기 위해서 리드 및 피치의 미세화가 요구되며 제조 과정에서 발생되는 버(burr)의 제거와 잔류응력 제거에 대한 노력이 필요하다. 본 논문은 리드프레임의 제작 시 스탬핑 공정 중에 발생하는 버와 잔류응력을 제거하기 위해 전해연마를 적용하였다. 전해연마를 적용한 리드프레임은 표면의 버 등이 제거되었으며, 잔류음력은 실험에 사용된 전해액의 종류에 따라 차이가 있으나, 과염소산계의 경우에는 잔류응력을 23%제거하여 리드프레임의 신뢰성을 높일 수 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.115.2-115.2
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• 2016

Al alloys are being used widely for automobile, aerospace and mechanical components because of their high strength ratio to weight. However, still they suffer from abrasion or corrosion owing to insufficient resistances to friction or mechanical impact and chemical attack. Plasma electrolytic oxidation (PEO) method is one of the promising surface treatment methods for Al alloys which can render better hardness than aluminum anodic oxide (AAO) films prepared by conventional anodizing method in acidic solutions. In this presentation, some basic nature of PEO film formation and growth process on Al alloys will be presented based on the experimental results obtained and discussed in view of dielectric breakdown and reformation and the role of various anions in film breakdown and reformation of PEO films.

• 열처리공학회지
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• 제24권4호
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• pp.209-216
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• 2011

Surface coatings were prepared on SKD11 core mold steel by plasma electrolytic oxidation (PEO). The coatings were investigated about the formation condition of core mold steel. SKD11 were coated by PEO in a mix solution of Sodium Aluminate $NaAlO_2$ (10 g/l), Sodium Silicate powder $Na_2SiO_3$ (0.5 g/l), Sodium tungstate dihydrate $Na_2WO_42H_2O$ (0.5 g/l) at less than $30^{\circ}C$. The electrical condition were voltage : 500~600 V; Pulse : 600~1800 Hz; current density 15~20 $A/dm^2$ various time : 3 min~40 min. The coatings surface morphology, cross-section, friction coefficient, hardness were investigated. The PEO coatings on SKD11 core mold steel showed the extended service life.

• 대한기계학회논문집A
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• 제39권12호
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• pp.1297-1303
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• 2015

장축의 내부 크롬도금은 크롬산 용액에 황산을 촉매로 경질의 후막 도금층을 형성시키는 기술로서 산업뿐만 아니라 군사적 목적으로도 널리 사용되고 있다. 대구경의 포신내부에 경질크롬도금을 처리하면 강성과 내마성을 증대시켜 고압의 폭발력에 견딜 수 있다. 탄자의 높은 운동에너지와 탄 폭발로 생긴 고압력에 의해 포신 내부의 크롬도금층이 탈락되는 문제가 있어 도금 공정 전반에 걸친 검토가 이루어졌다. 크롬도금은 탈지, 수세, 전해연마, 에칭, 도금, 수세 및 수소취성제거 등 여러 공정으로 이루어진다. 크롬도금 탈락은 도금의 밀착성과 연관이 있으며, 그 중에 전해연마액의 Fe 농도가 도금 밀착성에 영향을 미치는 것으로 나타났다. 도금부위의 요철상태를 SEM으로 조사하여 도금탈락을 방지할 수 있는 최적의 Fe 농도를 설정하고, 밀착성 시험 등으로 그 효과를 입증하였다.

• 한국표면공학회지
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• 제51권1호
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• pp.1-10
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• 2018

Anodic oxidation treatment of metals is one of typical surface finishing methods which has been used for improving surface appearance, bioactivity, adhesion with paints and the resistances to corrosion and/or abrasion. This article provides fundamental principle, type and characteristics of the anodic oxidation treatment methods, including anodizing method and plasma electrolytic oxidation (PEO) method. The anodic oxidation can form thick oxide films on the metal surface by electrochemical reactions under the application of electric current and voltage between the working electrode and auxiliary electrode. The anodic oxide films are classified into two types of barrier type and porous type. The porous anodic oxide films include a porous anodizing film containing regular pores, nanotubes and PEO films containing irregular pores with different sizes and shapes. Thickness and defect density of the anodic oxide films are important factors which affect the corrosion resistance of metals. The anodic oxide film thickness is limited by how fast ions can migrate through the anodic oxide film. Defect density in the anodic oxide film is dependent upon alloying elements and second-phase particles in the alloys. In this article, the principle and mechanisms of formation and growth of anodic oxide films on metals are described.

• 대한치과보철학회지
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• 제41권1호
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• pp.1-19
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• 2003

The surface of metals should be as smooth as possible for optimum comfort, oral hygiene, low plaque retention, and resistance to corrosion. In this study five specimens of each precious metal(type III gold alloy, ceramic gold alloy, and Ag-Pd alloy) were divided into five groups according to finishing and polishing procedures : group 1(sandblaster), group 2(group 1+stone), group 3(group 2+brown rubber), group 4(group 3+green rubber), and group 5(group 4+rouge). Six specimens of each non-precious metal(Co-Cr alloy, Ni-Cr alloy, and Co-Cr-Ti alloy) were divided into six groups: group 1(sandblaster), group 2(group 1+hard stone), group 3(group 2+electrolytic polisher), group 4(group 3+brown hard rubber point), group 5(group 4+green hard rubber point), and group 6(group 5+rouge). Considering factors affecting the rate of abrasion, the same dentist applied each finishing and polishing procedure. In addition, the surface roughness of enamel, resin, and porcelain was evaluated. The effect of finishing and polishing procedures on surface roughness of precious and non-precious metals, enamel, resin, and porcelain was evaluated by means of Atomic Force Microscope(AutoProbe CP. Park Scientific Instruments, U.S.A.) that can image the three dimensional surface profile and measure average surface roughness values of each sample at the same time. The obtained results were as follows : 1. According to finishing and polishing procedures, the surface roughness of type III gold alloy, ceramic gold alloy, and Ag-Pd alloy was decreased in the order of group 1, 2, 3, 4, and 5 (P<0.01). 2. According to finishing and polishing procedures. the surface roughness of Co-Cr alloy, Ni-Cr alloy, and Co-Cr-Ti alloy was decreased in the order of group 1, 2, 3, 4, 5, and 6 (p<0.01). 3. There was not statistically significant difference in the surface roughness among three metals of precious metals in group 1 but was significant difference in group 2, 3, 4, and 5 (P<0.05). 4. There was not statistically significant difference in the surface roughness among three metals of non-precious metals in all groups. 5. When the surface roughness of the smoothest surface of each metal, enamel. porcelain, and resin was compared, porcelain was the smoothest and the surface roughness was decreased in the order of Ni-Cr alloy. Co-Cr alloy. Co-Cr-Ti alloy, resin. Ag-Pd alloy, ceramic gold alloy type III gold alloy, and enamel (P<0.01). The results of this study indicate that the finishing and polishing procedures should be carried out in a logical, systematic sequence of steps and the harder non-precious metals may be less resistance to abrasion than are the softer precious metals.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.16-16
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• 2012

Mg and its alloys have been of great interest because of their low density of 1.7, 30% lighter than Al, but their wide applications have been limited because of their poor resistances against corrosion and/or abrasion. Corrosion resistance of Mg alloys can be improved by formation of anodic films using anodic oxidation method in aqueous electrolytes. Plasma electrolytic oxidation (PEO) is one of anodic oxidation methods by which hard anodic films can be formed as a result of micro-arc generation under high electric field. PEO method utilize not only substrate elements but also chemical components in electrolytes to form anodic films on Mg alloys. PEO films formed on AM50 magnesium alloy in an acidic fluozirconate electrolyte were observed to consist of mainly $ZrO_2$ and $MgF_2$. Liu et al reported that PEO coating on AM30 Mg alloy consists of $MgF_2$-rich outer porous layer and an MgO-rich dense inner layer. PEO films prepared on ACM522 Mg die-casting alloy in an aqueous phosphate solution were also reported to be composed of monoclinic $Mg_3(PO_4)_2$. $CeO_2$-incorporated PEO coatings were also reported to be formed on AZ31 Mg alloys in $CeO_2$ particle-containing $Na_2SiO_3$-based electrolytes. Magnesium tin hydroxide ($MgSn(OH)_6$) was also produced on AZ91D alloy by PEO process in stannate-containing electrolyte. Effects of $OH^-$, $F^-$, $PO{_4}^{3-}$ and $SiO{_3}^{2-}$ ions and alloying elements of Al and Sn on the formation of PEO films on pure Mg and Mg alloys and their protective properties against corrosion have been investigated in this work. $PO{_4}^{3-}$, $F^-$ and $SiO{_3}^{2-}$ ions were observed to contribute to the formation of PEO films but $OH^-$ ions were found to break down the surface films under high electric field. The effect of pulse current on the formation of PEO films will be also reported.