• 한국레이저가공학회지
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• 제2권3호
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• pp.52-61
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• 1999

The laser induced forward transfer(LIFT) technique employs a pulsed laser to transfer parts of a thin metal film from an optically transparent target onto an arbitrary substrate in close proximity to the metal film on the target. In this work, a two-step method, the combination of LIFT process, in which a Au film deposited on the $Al_2$O$_3$ substrate by Nd:YAG laser and subsequent Au electroless metal plating on the by LIFT process generated Au seed, was presented. The influence of laser parameters, wavelength, laser power, film thickness and overlap ratio of pulse tracks, on the shapes of deposit and conductor line after electroless plating is experimentally studied. As a results, the threshold power densities for ablation, deposition and metallization were determined and comparison of threshold value between the wave length 1064nm and the second harmonic generated 532nm. In odor to determine a possible application in the electronic industry, a smallest conduct spot size, line width and isolated line space were generated.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.49-52
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• 1999

Tailored-welded blanks are used for forming of automobile structural and skin components. Its main objective is to achieve weight and production cost reduction in manufacturing of the components. For successful application of tailored-welded blanks design of initial welded blanks and prediction of welding line movement are critical. Here the utilization of the backward tracing scheme of the finite element method shows to be desirable in design of initial welded blanks for net-shape production and in prediction of the welding line movement. First the design of initial blank in forming of welded thick sheet with isotropy is tried and it appears successful in obtaining a net-shape stamping product. Based in the first approach the backward tracing scheme is applied to anisotropic tailored blank. The welding line movement is also discussed.

• 한국생산제조학회지
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• 제24권1호
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• pp.31-37
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• 2015

A laser line welder using a solid-state laser (Yb:YAG) has been manufactured for joining ultra-thin cold-rolled steel coils in steelworks. The coils to be welded primarily range from 0.15 to 0.3 mm in thickness and 800 to 1,100 mm in width. Because the steel plate is extremely thin, it is very important to control the stop positions of the clamp at cutting and welding points. In this study, both hydraulic proportional control valves and LVDT sensor embedded cylinders were used to precisely control and monitor the positions of clamps with complementary stoppers. As a result, the positions could be controlled within an error of ${\pm}30{\mu}m$. Erichsen cupping tests on the welded joints show that the Erichsen index ranges from 4.4 to 4.6 mm. Furthermore, the tensile strength of welding points is comparable to that of the base metal.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.142-144
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• 2009

We demonstrated narrow and good aspect-ratio inkjet-printed silver lines with multi-time over-printing methods. By using this strategy, narrow silver lines were obtained with 200 nm thickness and their width and gap between printed lines of uniform narrow silver lines were 30 ${\mu}m$ and 17 ${\mu}m$, respectively. It also had good conductivity, sheet resistacne of 0.36 ${\Omega}/{\square}$ and specific resistance of $8{\mu}{\Omega}{\cdot}cm$. In current stress test, narrow silver line with 30 ${\mu}m$ width was able to a current flow up to 50 mA (2.1A/$cm^2$). Using surface treatment on poly-arylate substrate with $UVO_3$, we obtained clean-edge narrow line without any edge waviness.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 제5회 박판성형 SYMPOSIUM
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• pp.49-54
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• 2006

During most of manufacturing processes of auto-body panels, the trimming line should be designed in advance prior to flanging. It is an important task to find a feasible trimming line to obtain a precise final part shape after flanging. This paper proposes a new fast method to find feasible trimming line based on one-step analysis. The basic idea of the one-step analysis is to seek for the nodal positions in the initial blank from the final part, and then the distribution of strain, stress and thickness in the final configuration can be calculated by comparing the nodal position in the initial blank sheet with the one of the final part. The one-step analysis method is able to predict the trimming line before flanging since the desired product shape after flanging can be defined from the final configuration and most of strain paths are simple during the flanging process. Finally, designers can obtain a discrete trimming line from the boundary of the developed meshes after one-step analysis and import it into CAD system in the early design stage. The proposed method has been successfully applied to two basic curve flanging processes demonstrating many advantages.

• 한국해양공학회지
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• 제20권4호
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• pp.24-30
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• 2006

Different methods exist for the estimation of thermaldeformation of plates in the line heating process. These are based on the assumption of residual strains in the heat-affected zone, known as the method of inherent strains, or simulated relations between heating conditions and residual deformations. The purpose of this paper is to develop a simulator of thermal deformation in the line heating, using the artificial neural network. Curvature deformations for the plate-forming are investigated, which can be used as a prime deformation parameter in the process. The curvature of plates are calculated using the approximation of plate surface by NURBS. Line heating experiments for 11 specimens of different thickness and heating conditions were performed. Two neural networks predicting the maximum temperature and curvature deformations at the heating line are studied. It was concluded that the thermal deformations predicted by the neural network can be used in a line heating simulator, which is considered an attractive and practical alternative to the existing methods.

• 마이크로전자및패키징학회지
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• 제23권2호
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• pp.79-84
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• 2016

유연전자소자가 외부힘에 의해 변형될 경우 반도체 다이가 기계적 응력 때문에 변형되거나 파괴되고 이러한 변형이나 파괴는 channel의 전자이동도를 변화시키거나 배선의 저항을 증가시켜 집적회로의 동작 오류를 발생시킨다. 따라서 반도체 집적회로는 굽힘 변형이 발생해도 기계적 응력이 발생하지 않는 중립축에 위치하는 것이 바람직하다. 본 연구에서는 굽힘변형을 하는 flip-chip 접합공정이 적용된 face-down flexible packaging system에서 중립축의 위치와 파괴 모드를 조사하였고 반도체 집적회로와 집중응력이 발생한 곳의 응력을 감소시킬 수 있는 방법을 제시하였다. 이를 위해, 설계인자로 유연기판의 두께 및 소재, 반도체 다이의 두께를 고려하였고 설계인자가 중립축의 위치에 미치는 영향을 조사한 결과 유연기판의 두께가 중립축의 위치를 조절하는데 유용한 설계인자임을 알 수 있었다. 3차원 모델을 이용한 유한요소해석 결과 반도체 다이와 유연기판 사이의 Cu bump 접합부에서 항복응력보다 높은 응력이 인가될 수 있음을 확인하였다. 마지막으로 flexible face-down packaging system에서 반도체 다이와 Cu bump 의 응력을 감소시킬 수 있는 설계 방법을 제안하였다.

• 한국정밀공학회지
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• 제29권10호
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• pp.1144-1148
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• 2012

Process conditions for generating nano patterns handle different process according to the pattern characteristics, and different process data according to patterns in questions. To efficiently find optimal process conditions for generating nano patterns, process data by experiment is needed consideration of the pattern characteristics concerning the equipment. In particular, coating methods of a cylindrical mold differ from it of a flat plate because of viscosity of coating materials. Also the coating thickness affects nano process and pattern line width. So coating method of coating thickness for cylindrical mold is very important on nano pattern generating. In this study, a method is proposed for coating Photo Resist through the spray in order to coat cylindrical mold and measuring the thickness of coating using measuring tip considering the size of cylindrical mold because there is no method in the existing SEM. The proposed method is applied to a real printed electronics system to verify its accuracy and efficiency.

• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.202-207
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• 2017

This paper presents the performance of a planar, low-profile, and wide-gain-bandwidth leaky-wave slit antenna in different thickness values of high-permittivity gallium arsenide substrates at terahertz frequencies. The proposed antenna designs consisted of a periodic array of $5{\times}5$ metallic square patches and a planar feeding structure. The patch array was printed on the top side of the substrate, and the feeding structure, which is an open-ended leaky-wave slot line, was etched on the bottom side of the substrate. The antenna performed as a Fabry-Perot cavity antenna at high thickness levels ($H=160{\mu}m$ and $H=80{\mu}m$), thus exhibiting high gain but a narrow gain bandwidth. At low thickness levels ($H=40{\mu}m$ and $H=20{\mu}m$), it performed as a metasurface antenna and showed wide-gain-bandwidth characteristics with a low gain value. Aside from the advantage of achieving useful characteristics for different antennas by just changing the substrate thickness, the proposed antenna design exhibited a low profile, easy integration into circuit boards, and excellent low-cost mass production suitability.

• 대한화학회지
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• 제35권5호
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• pp.539-544
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• 1991

X-ray Compton 산란선의 강도를 측정하여 내지문처리재(Anti-fingerprint Steel)의 표면에 Coating 되어 있는 Silicone resin film의 두께를 신속하게 측정할 수 있는 새로운 분석방법을 연구하였다. Silicone resin과 같은 유기수지들은 C, H, O, Si 등과 같은 경원소들로 구성되어 있어 compton 산란선의 강도가 높게 나타나는데 이러한 성질을 이용, X-ray tube로부터 발생된 RhK$_{\alpha}$ 선을 시료표면에 조사한 후 발생된 RhK$_{\alpha}$ compton 산란선의 강도를 측정하여 silicone resin film의 두께를 구하였다. 검량곡선 작성결과 0.2 ~ 5.0 ${mu}$m 범위에서 직선성을 나타냈으며 두께측정에 대한 정확도는 0.22 ${mu}$m 이었다.