• Journal of Surface Science and Engineering
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• v.45 no.1
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• pp.20-24
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• 2012

Multilayer passivation film on OLED with organic/inorganic hybrid structure as to diminish the thermal stress and expansion was researched to protect device from the direct damage of $O_2$ and $H_2O$ and improve life time characteristics. Red OLED doped with 1 vol.% Rubrene in $Alq_3$ was used as a basic device. The films consist of ITO(150 nm)/ELM200_HIL(50 nm)/ELM002_HTL(30 nm)/$Alq_3$: 1 vol.% Rubrene(30 nm)/$Alq_3$(30 nm) and LiF(0.7 nm)/Al(100 nm) which were formed in that order. Using LiF/$SiN_x$ as a buffer layer was determined because it significantly improved life time characteristics without suffering damage in the process of forming passivation film. Multilayer passivation film on buffer layer didn't produce much change in current efficiency, while the half life time at 1,000 $cd/m^2$ of OLED/LiF/$SiN_x$/E1/$SiN_x$ was 710 hours which showed about 1.5 times longer than OLED/LiF/$SiN_x$/E1 with 498 hours. futhermore, OLED/LiF/$SiN_x$/E1/$SiN_x$/E1/$SiN_x$ with 1301 hours showed about twice than OLED/LiF/$SiN_x$/E1/$SiN_x$ which demonstrated that superior characteristics of life time was obtained in multilayer passivation film. Through the above result, it was suggested using LiF/$SiN_x$ as a buffer layer could reduce the damage from the difference of thermal expansion coefficient in OLED with protective films, and epoxy layer in multilayer passivation film could function like a buffer between $SiN_x$ inorganic layers with relatively large thermal stress.

• Corrosion Science and Technology
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• v.21 no.2
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• pp.121-129
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• 2022

A study on water-based epoxy coated on mild steel using the electroplating method was conducted to optimize the process parameters for dry film thickness to achieve superior paint quality at optimal cost in an automotive plant. The regression model was used to adjust various parameters such as electrode voltage, bath temperature, processing time, non-volatile matter, and surface area to optimize the dry film thickness. The average dry film thickness computed using the model was in the range of 15 - 35 ㎛. The error in the computed dry film thickness with reference to the experimentally measured dry film thickness value was - 0.5809%, which was well within the acceptable limits of all paint shop standards. Our study showed that the dry film thickness on mild steel was more sensitive to electrode voltage and bath temperature than processing time. Further, the presence of non-volatile matter was found to have the maximum impact on dry film thickness.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.382-387
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• 2005

An electrochemical evaluation on the corrosion resistance for heavy anticorrosive paint was carried out for 5 kinds of heavy anticorrosive paints such as High solid epoxy(HE), Solvent epoxy(SE), Tar epoxy(TE), Phenol epoxy(PE), and Ceramic epoxy(CE) as parameters of DFT(Dry Film Thickness, 25${\mu}m$50${\mu}m$, solution condition(Flow of Nonflow). Corrosion current density of HE(DFT 50${\mu}m$ in case of flow condition was larger than that of nonflow condition. However, their values of the other anticorrosive paints were decreased compared to the nonflow condition. The values of AC impedance were increased with increasing of DFT regardless of kinds of anticorrosive paints. And the polarization resistance of cyclic voltammogram showed a good tendency to correspond with well the values of AC impedance measurement. HE and CE had a relatively good corrosion resistance than other heavy anticorrosive paint.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.11a
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• pp.71-71
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• 2004

• Journal of Information Display
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• v.4 no.1
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• pp.17-23
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• 2003

A thermoset type anisotropic conductive adhesive film (ACAF) comprising epoxy resin and natural butyl rubber (NBR) as the binder, micro-encapsulated imidazole as the curing agent, and Ni/Au coated polymer bead as a conductive particle has been studied. These films have been prepared to respond to requirements such as improved contact resistance, current status less of than 60 ${\mu}m$ and reliability. These films can also be used for connection between the ITO glass for LCD panel and the flexible circuit board. The curing conditions for the connection were 40, 20 and 15 seconds at 150, 170 and 190 $^{\circ}C$, respectively. The initial contact resistance and adhesion strength were 0.5 ${\Omega}/square$ and 0.4 kg/cm under the condition of 30 kgf/$^{cm}^2}$, respectively. After completing one thousand thermal shock cycling tests between -15 $^{\circ}C$ and 100 $^{\circ}C$, the contact resistance was maintained below 0.7 ${\Omega}/square$. Durability against high temperature (80$^{\circ}C$) and high humidity (85 % RH) was also tested to confirm long-term stability (1000 hrs) of the conduction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.165-165
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• 2009

현재 반도체나 이동통신 분야는 사용자의 요구에 따라 PCB의 회로선폭이 갈수록 좁아지고 있다. 이러한 정밀 부품을 제조하기 위한 제조공정에서 각광받기 시작한 기술 중 하나가 대기압 플라즈마 기술이다. 본 연구에서는 미세패턴 형성이 가능한 에폭시 본딩 필름위에 무전해 도금공정을 통한 패턴 도금법을 이용하여 패턴을 형성하였고, 형성된 패턴에 대기압 플라즈마 처리 횟수에 따른 접촉각(Contact Angle)과 Peel Strength의 변화를 분석하였다. 또한 에폭시 본딩 필름을 이용한 Build-up공정을 거쳐 Micro Via를 형성하여 대기압 플라즈마 처리 횟수에 따른 Via 표면을 분석하였다. 대기압 플라즈마 기술은 진공식에 비해 소규모 장비를 이용한 전처리가 가능하고, 초기 설비비용을 절감하는데 탁월한 효과가 있어 널리 사용하는 기술 중 하나이다. 이 연구를 통하여 대기압 플라즈마 처리 횟수에 따른 표면에너지의 변화로 인한 접촉각이 좋아지는 것을 알 수 있으며, 대기압 플라즈마 처리를 한 패턴표면이 친수성으로 변하면서 현상된 드라이 필름 사이로 도금액이 원활히 공급되어서 미세패턴 모양이 우수하게 구현되었음을 알 수 있었다. 또한 Via Filling에도 뛰어난 효과가 있었음을 확인할 수 있었다.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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• pp.65-70
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• 2014

Warpage of top packages to form thin package-on-packages was measured with progress of their process steps such as PCB substrate itself, chip bonding, and epoxy molding. The $100{\mu}m$-thick PCB substrate exhibited a warpage of $136{\sim}214{\mu}m$. The specimen formed by mounting a $40{\mu}m$-thick Si chip to such a PCB using a die attach film exhibited the warpage of $89{\sim}194{\mu}m$, which was similar to that of the PCB itself. On the other hand, the specimen fabricated by flip chip bonding of a $40{\mu}m$-thick chip to such a PCB possessed the warpage of $-199{\sim}691{\mu}m$, which was significantly different from the warpage of the PCB. After epoxy molding, the specimens processed by die attach bonding and flip chip bonding exhibited warpages of $-79{\sim}202{\mu}m$ and $-117{\sim}159{\mu}m$, respectively.

• Journal of Surface Science and Engineering
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• v.51 no.2
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• pp.95-103
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• 2018

Recently, many types of constructional steels have been often exposed to under severe corrosive environments due to acid rain with increasing environmental contamination. In order to inhibit their corrosion in severe corrosive environments, a painting method has been widely applied to numerous constructional steels of land as well as marine. Therefore, development of paint having a good quality of corrosion resistance is considered to be very important. In this study, four types of anti-corrosive paints (AP: Phenol epoxy, AC: Ceramic epoxy, AT: Coal tar epoxy, AH: High solid epoxy) were coated to the specimens, and then, were immerged in various salt solutions (0.1, 0.3, 3, 6, 9 and 15% NaCl solutions) for 11 days. And, the corrosion resistance of these samples by effect of osmotic pressure with salt concentration was investigated with electrochemical methods such as measurement of corrosion potential, impedance and corrosion current density. The corrosion current densities of all samples (AC, AT and AH) submerged in 3% NaCl solution exhibited the smallest values compared to other salt solutions. However, in the case of lower values of salt solutions than 3% NaCl solution, the corrosion current density increased again because it makes easier for water, dissolved oxygen and chloride ion etc. to invade toward inner side of coating film due to increasing of the osmotic pressure than 3% NaCl solution, but in the case of higher values of salt solutions than 3% NaCl solution, the coating film is easily deteriorated due to high concentration of chloride ion rather than the osmotic pressure, which resulted in increasing the corrosion current density. In particular, the AC sample indicated the best corrosion resistance in 6% NaCl solution compared to other samples. Consequently, it is considered that the corrosion mechanism of the coated steel plate is completely different from bare steel plate, and the corrosion resistance of coating film by osmotic pressure and chloride ion depend on various types of epoxy of paint in NaCl solution.

• Composites Research
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• v.12 no.2
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• pp.36-45
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• 1999

Since carbon fiber epoxy composite materials have excellent properties for structures due to their high specific strength, high modulus, high damping and low thermal expansion, the hollow shafts made of carbon fiber epoxy composites have been widely used for power transmission shafts for motor vehicles, spindles of machine tools and rollers for film manufacturing. However, the molded composite shafts are not usually accurate enough for mechanical machine elements, which require turning or grinding of composite hollow shafts. In this paper, the grinding characteristics of composite hollow shafts, which are flexible in the radial and circumferential directions, were investiaged experimentally and analytically with respect to the stacking angle, thickness and outer diameter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.12
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• pp.751-756
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• 2017

A molding-type power inductor is an inductor that uses a hybrid material that is prepared by mixing a ferrite metal powder coated with an insulating layer and an epoxy resin, which is injected into a coil-embedded mold and heated and cured. The fabrication of molding-type inductors requires various techniques such as for coil formation and insertion, improving the magnetic properties of soft magnetic metal powder, coating an insulating film on the magnetic powder surface, and increasing the packing density by well dispersing the powder in the epoxy resin. Among these aspects, researches on additives that can disperse the metal soft magnetic powder having the greatest performance in the epoxy resin with high charge have not been reported yet. In this study, we investigated the effect of silanes, KBM-303 and KBM-403, and a commercial dispersant on the dispersion of metal soft magnetic powders in epoxy resin. The sedimentation height and viscosity were measured, and it was confirmed that the silane KBM-303 was suitable for dispersion. For this silane, the packing density was as high as about 72.49%. Moreover, when 1.2 wt% of dispersant BYK-103 was added, the packing density was about 80.5%.