• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.326-334
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• 2010

Porous and net-shaped tantalum powder for a capacitor was formulated in a SHS (self-propagating high-temperature synthesis) process. However, this powder, which has weak strength among its particles and low flow ability, cannot be used for a capacitor. Therefore, this powder was sintered in a high-vacuum furnace to increase agglomeration to improve the flow ability, bonding strength among the particles, and shrinkage during pellet sintering. Finally, it was deoxidated with 2 wt% Mg powder to remove the increased surface oxygen that arose during the sintering process. The final product was analyzed in terms of its chemical and physical properties and was compared with a commercial powder used by a capacitor manufacturer.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.1-5
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• 2017

Many microelectronic devices are miniaturizing the capacitance density and the size of the capacitor. Along with this miniaturization of electronic circuits, tantalum (Ta) capacitors have been on the market due to its large demands worldwide and advantages such as high volumetric efficiency, low temperature coefficient of capacitance, high stability and reliability. During a tantalum capacitor manufacturing process, arc welding has been used to weld base frame and sub frame. This arc welding may have limitations since the downsizing of the weldment depends on the size of welding electrode and the contact time may prevent from improving productivity. Therefore, to solve these problems, this study applies laser spot welding to weld nickel (Ni) and Au-Sn-Ni alloy using CW IR fiber laser with lap joint geometry. All laser parameters are fixed and the only control variable is laser irradiance time. Four different shapes, such as no melting upper workpiece, asymmetric spherical-shaped weldment, symmetric weldment, and, excessive weldment, are observed. This shape may be due to different temperature distribution and flow pattern during the laser spot cutting.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.338-343
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• 2009

The purpose of this study is to make the tantalum powder for solid electrolyte capacitor with SHS (self-propagating high-temperature synthesis) process. Raw materials for manufacturing Ta powder were used $Ta_{2}O_{5}$, Mg and NaCl. While progressing SHS process, $Ta_{2}O_{5}$ powder was reduced by Mg powder. The combustion temperature and velocity were easily controled by the varying mole ratio of NaCl, Mg and initial reaction pressure. In the case of only using NaCl as an inorganic agent, the shape is unagglomerated and has high surface area. whereas we were given the powder which has good net structure by the addition of excessive Mg as a diluent.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.73-74
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• 1998

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.7-8
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• 2004

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.12
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• pp.1016-1022
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• 2001

This study presents the microstructure-electrical property relationship of reactive-sputtered Ta$_2$O$_{5}$ MIM capacitor structure processed by annealing in a vacuum and $O_2$ ambience. A microstructural investigation showed the existence of amorphous phase in as-deposited condition and the formation of preferentially oriented-Ta$_2$O$_{5}$ in $700^{\circ}C$ annealing. On annealing under the $O_2$ atmosphere, the Ta$_2$O$_{5}$ film exhibited the trend of its composition\`s approaching to stoichiometry from off-stoichiometry, analyzed by EPMA, the leakage current decrease and the enhanced temperature-capacitance characteristic stability. In the case of low temperature vacuum-annealing treatment, the leakage current behavior was stable irrespective of applied electric field. In the high temperature-annealed film at a vacuum condition, the electrical properties was observed to deteriorate. The results state that in Ta$_2$O$_{5}$ film annealed at $O_2$ atmosphere, gives rise to improvement of electrical characteristics in the capacitor were improved by reducing oxygen-vacancy and dandling Ta-O bond.-O bond.

• Journal of Sensor Science and Technology
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• v.13 no.3
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• pp.195-198
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• 2004

For a diffusion barrier against copper, tantalum nitride films have been deposited on $SiO_{2}$ by atomic layer deposition (ALD), using PEMAT(Pentakis(ethylmethylamino)tantalum) and $NH_{3}$ as precursors, Ar as purging gas. The deposition rate of TaN at substrate temperature $250^{\circ}C$ was about $0.67{\AA}$ per one cycle. The stability of TaN films as a Cu diffsion barrier was tested by thermal annealing for 30 minutes in $N_{2}$ ambient and characterized through XRD, sheet resistance, and C-V measurement(Cu($1000{\AA}$)/TaN($50{\AA}$)/$SiO_{2}$($2000{\AA}$)/Si capacitor fabricated), which prove the TaN film maintains the barrier properties Cu below $400^{\circ}C$.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.386-390
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• 2009

Niobium(Nb) and Tantalum(Ta) are rarely found apart in nature and never in the free state. The element niobium amounts to 3% of the crustal abundance. On the whole, the niobium capacitor showed somewhat more unstable characteristics than the commercial tantalum capacitors, but is nonetheless considered applicable as a future substitute for tantalum capacitors. In this study, niobium powder was made from potassium heptafluoroniobite($K_2NbF_7$) by using sodium(Na) as a reductant and KCl and KF as diluents based on the hunter sodiothermic reduction method.,In order to obtain a high surface area niobium powder via the sodiothermic reduction method, a certain amount of diluent, such as alkali metal halides selected from NaCl, KCl, KF and NaF, was added in the raw materials to be reduced. However, if a higher surface area of powder is required, more diluents need to be used in the said method in order to produce niobium powder. But when more diluents are used, the niobium powder will be contaminated with more impurities and the yield will also decreased.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.9
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• pp.81-88
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• 2015

LED has been great attentions in lighting industry because of its long life-time, high efficiency, excellent light output characteristics. However, the life-time of the LED driving system is decreased because of the electrolytic capacitor which is used in the power conversion system for driving LED lighting. Therefore the capacitance reduction methods have been studied to replace an electrolytic capacitor with film or tantalum capacitor. This paper presents the Single stage PFC flyback converter with the simplified third harmonic current injection circuit to reduce output capacitance and the proposed system is theoretically analyzed and verified through the experiment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.348-348
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• 2005

High capacitance MLCC has been enabled through the use of nickel electrodes to produce thinner layers at acceptable costs. High capacitance MLCC devices offer significant advantages to electrolytics such as tantalum and aluminum ; Lower ESR for high frequency applications. Non-polarized. Many process improvement have enabled this technology Higher dielectric constants Thinner dielectric and electrode layers through BME More accurate layer construction. This study is high capacitance MLCC electrical propertics. reliability, Analysis on DOE(Design Of Experiment) of the electical propertics.