• 한국공작기계학회논문집
• /
• 제14권5호
• /
• pp.13-20
• /
• 2005

Micro EDM process is generally used for machining microholes, cavities, and three dimensional shapes. For machining micro structures, first of all, micro tool electrode is indispensable and WEDG system is proposed for tool fabrication method. When using WEDG, its machining characteristics are highly affected by many EDM parameters such as applied voltage, current, rotation speed, capacitance, and pulse duration. Therefore, the design of experiment is introduced to fully understand the effect of the EDM parameters on machining tool electrode. And an attempt has been made to develop the mathematical model for predicting the size of the tool electrode by calculating spark distance. The suggested model was verified with experiment and predicted working gap distance is in good accord with the measured value.

• Transactions on Electrical and Electronic Materials
• /
• 제11권2호
• /
• pp.89-91
• /
• 2010

Partial discharge (PD) resistances were investigated for three types of samples: original epoxy resins, epoxy micro composites with and without the silane processing, and mixture composites with micro and nano particles. The PD was applied to these materials using rod, gap, and plane electrodes. The partial discharge resistance found in the micro composites was better than that found in the original epoxy resin. Moreover, the mixture composites of $SiO_2$ nano and micro particles had much larger resistances than the original epoxy resin or microcomposites. It can be regarded that this excellent property was due to the fact that the nano particles have a dense structure between the micro particles.

• Transactions on Electrical and Electronic Materials
• /
• 제12권4호
• /
• pp.131-134
• /
• 2011

Back-end-of-line using ultra low-k (ULK; k < 2.5) has been required to reduce resistive capacitance beyond 45 nmtechnologies, because micro-processing units need higher speed and density. There are two strategies to manufacture ULK inter-layer dielectric (ILD) materials using an air-gap (k = 1). The former ULK and calcinations of ILD degrade the mechanical strength and induce a high cost due to the complication of following process, such as chemical mechanical polishing and deposition of the barrier metal. In contrast, the air-gap based low-k ILD with a relatively higher density has been researched on the trench-type with activity, but it has limited application to high density devices due to its high air-gap into the next metal layer. The height of air-gap into the next metal layer was reduced by changing to the via-typed air-gap, up to about 50% compared to that of the trench-typed air-gap. The controllable ULK was easily fabricated using the via-typed air-gap. It is thought that the via-type air-gap made the better design margin like via-patterning in the area with the dense and narrow lines.

• Design & Manufacturing
• /
• 제10권3호
• /
• pp.8-13
• /
• 2016

Despite technological advance, there have been several troubles in photo reaction injection molding (photo RIM) to produce ultra thin light guide panels (LGPs). In this study, micro leakage problem at cavity edge during photo RIM was investigated numerically. In order to obtain optimal processing conditions, we regulated inlet pressure of injected resin at the cavity edge and figured out micro leakage behaviors. At low inlet pressure (less than 100 Pa), though the micro leakage problem was not occurred, another problem, short shot due to not enough driving force, was appeared More than 1,000 Pa of the inlet pressure, injected resin was rapidly leaked through the micro gap at the cavity edge. Finally, we obtained optimal inlet pressure around 600 ~ 1,000 Pa. At this region, injected resin fully filled the cavity without micro leakage behavior. Based on the present study, further comparative investigations with experimental photo RIM should be performed to find optimal processing conditions for produce ultra thin LGPs.

• 한국정밀공학회지
• /
• 제20권8호
• /
• pp.213-220
• /
• 2003

By the localization of electro-chemical dissolution region, we succeeded in a few micrometer size hole drilling on stainless steel with the radial machining gap of about 1 ${\mu}{\textrm}{m}$. Tens of nanosecond duration voltage pulses were applied between WC micro-shaft and stainless steel in the 0.1 M $H_2SO_4$ solution. Pt balance electrode was used to drill the high aspect ratio micro-hole without generation of Cr oxide layer on the machined surface. The effects of applied voltage, pulse duration, and pulse period on localization distance were investigated according to machining time. We suggested the taper reduction technique especially brought up on blind-hole machining. High quality micro-holes with 8 ${\mu}m$ diameter with 20 ${\mu}m$ depth and 12 ${\mu}m$ diameter with 100 ${\mu}m$ depth were drilled on 304 stainless steel foil. The various hole shapes were also produced including stepped holes and taper free holes.

• Journal of Welding and Joining
• /
• 제12권4호
• /
• pp.110-116
• /
• 1994

This paper has been researched bondability of electronics devices, such as lead frame and the thick film of Ag/Pd on an alumina substrate by different heat sources. To obtain the bonds with high quality, it is very important to consist of different materials. Therefore, this paper clarifies not only heat mechanism of micro parallel gap resistance bonding method and pulse heat tip bonding method but also investigates selection of heat sources with micro-electronic materials for bonding. Finally, it is realized fluxless bonding process with filler metal such as plating layers.

• 한국정밀공학회지
• /
• 제28권3호
• /
• pp.308-314
• /
• 2011

In micro electrochemical machining (micro ECM), machining conditions have been determined to maintain a small side gap and to machine a workpiece stably However, machining speed is slow. To improve machining speed while maintaining the form accuracy, the paper investigates machining parameters such as pulse amplitude, duty ratio, pulse on-time, and the electrolyte's temperature and concentration. The experiment in this study shows that the electrolyte's concentration is the key factor that can reduce machining time while maintaining the form accuracy Micro square columns were fabricated to confirm the machining parameters' effects.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1816-1818
• /
• 1996

A micro-size nonthermal plasma generator, using a $SiO_2$ film as a dielectric barrier, has been studied experimentally for a high frequency ac voltage in 2LPM oxygen gas fed. The $SiO_2$ film as a micro-size dielectric barrier was made by the wet oxidation of n-type Si wafer($220[{\mu}mt]$). It can be generated ozone, as a nonthermal plasma intensity parameter, at very low level of applied voltage about 1[kV] by using the micro-size dielectric barrier. As a result, in case that have no air gap spacing i.e. surface discharge case shows relatively higher ozone concentration rather than that case of the micro-airgap spacing.

• 한국정밀공학회지
• /
• 제22권5호
• /
• pp.37-44
• /
• 2005

In this paper, wire electrochemical machining (Wire ECM) with ultra short pulses is presented. Platinum wire with $10{\mu}m$ diameter was used as a tool and 304 stainless steel was locally dissolved by electrochemical machining in 0.1M $H_{2}SO_4$ electrolyte. Wire ECM can be easily applied to the fabrication of arbitrarily shaped micro-grooves without tool wear. The change of machining gap according to applied pulse voltage, pulse on-time and pulse period was investigated and the optimal pulse condition for stable machining was obtained. Using this method, various micro-grooves with less than $20{\mu}m$ width were fabricated.

• Journal of Electrical Engineering and Technology
• /
• 제12권2호
• /
• pp.858-864
• /
• 2017

This study aims to restrain free conducting wire-type particles which are commonly and dangerously existing within DC gas-insulated transmission lines. A realistic platform of a coaxial cylindrical electrode was established by using a high-speed camera and a partial discharge (PD) monitor to observe the motion, PD, and breakdown of these particles. The probabilities of standing or bouncing, which can be affected by the length of the particles, were also quantitatively examined. The corona images of the particles were recorded, and particle-triggered PD signals were monitored and extracted. Breakdown images were also obtained. The air-gap breakdown with the particles was subjected to mechanism analysis on the basis of stream theory. Results reveal that the lifting voltage of the wire particles is almost irrelevant to their length but is proportional to the square root of their radius. Short particles correspond to high bouncing probability. The intensity and frequency of PD and the micro-discharge gap increase as the length of the particles increases. The breakdown voltage decreases as the length of the particles decreases.