• ETRI Journal
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• v.34 no.5
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• pp.713-718
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• 2012

Sensor nodes in ubiquitous sensor networks require autonomous replacement of deteriorated gas sensors with reserved sensors, which has led us to develop an encapsulation technique to avoid poisoning the reserved sensors and an autonomous activation technique to replace a deteriorated sensor with a reserved sensor. Encapsulations of $In_2O_3$ nanoparticles with poly(ethylene-co-vinyl alcohol) (EVOH) or polyvinylidene difluoride (PVDF) as gas barrier layers are reported. The EVOH or PVDF films are used for an encapsulation of $In_2O_3$ as a sensing material and are effective in blocking $In_2O_3$ from contacting formaldehyde (HCHO) gas. The activation process of $In_2O_3$ by removing the EVOH through heating is effective. However, the thermal decomposition of the PVDF affects the property of the $In_2O_3$ in terms of the gas reactivity. The response of the sensor to HCHO gas after removing the EVOH is 26%, which is not significantly different with the response of 28% in a reference sample that was not treated at all. We believe that the selection of gas barrier materials for the encapsulation and activation of $In_2O_3$ should be considered because of the ill effect the byproduct of thermal decomposition has on the sensing materials and other thermal properties of the barrier materials.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.179-179
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• 2001

• Journal of the Korean institute of surface engineering
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• v.46 no.4
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• pp.162-167
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• 2013

Encapsulation is required since organic materials used in OLED devices are fragile to water vapor and oxygen. Laser sealing method is currently used where IR laser is scanned along the glass-frit coated lines. Laser method is, however, not suitable to encapsulating large-sized glass substrate due to the nature of sequential scanning. In this work we propose a new method of encapsulation using Joule heating. Conductive layer is patterned along the sealing lines on which the glass frit is screen printed and sintered. Electric field is then applied to the conductive layer resulting in bonding both the panel glass and the encapsulation glass by melting glass-frit. In order to obtain uniform bonding the temperature of a conductive layer having a shape of closed loop should be uniform. In this work we conducted simulation for heat distribution according to the structure of a conductive layer used as a Joule-heat source. Uniform temperature was obtained with an error of 5% by optimizing the structure of a conductive layer. Based on the results of thermal simulations we concluded that Joule-heating induced encapsulation would be a good candidate for encapsulation method especially for large area glass substrate.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.41-48
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• 2010

To improve the pot life of one-part in-house anisotropic conductive paste (ACP) formulations, 2-methyl imidazole curing accelerator powders were encapsulated with five agents. Through measuring the melting point of the five agents using DSC, it was confirmed that a encapsulation process with liquid-state agents is possible. Viscosity of ACP formulations containing the encapsulated imidazole powders was measured as a function of storage time from viscosity measurements. As a result, pot life of the formulations containing imidazole powders encapsulated with stearic acid and carnauba wax was improved, and these formulations indicated similar curing behaviors to a basic formulation containing rare imidazole. However, the bondlines made of these formulations exhibited low average shear strength values of about 37% level in comparison with the basic formulation.

• Journal of the Semiconductor & Display Technology
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• v.13 no.4
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• pp.15-20
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• 2014

The fracture analysis of $SiN_x$ layers, which were deposited by low-temperature plasma enhanced chemical vapor deposition (LT-PECVD) and could be used for an encapsulation layer of a flexible organic light emitting display (OLED), was performed by an electrical method. The specimens of metal-insulator-metal (MIM) structure were prepared using Pt and ITO electrodes. We stressed MIM specimen mechanically by bending outward with a bending radius of 15mm repeatedly and measured leakage current through the top and bottom electrodes. We also observed the cracks, were generated on surface, by using optical microscope. Once the cracks were initiated, the leakage current started to flow. As the amount of cracks increased, the leakage current was also increased. By correlating the electrical leakage current in the MIM specimen with the bending times, the amount of cracks in the encapsulation layer, generated during the bending process, was quantitatively estimated and fracture behavior of the encapsulation layer was also closely investigated.

• Macromolecular Research
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• v.13 no.3
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• pp.223-228
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• 2005

In the present work, a low-density polyethylene (LDPE) composite, filled with Zn-ion coated structural silica encapsulated with the diglycidyl ether of bisphenol-A (DGEBA), was synthesized using the conventional melt-blending technique in a sigma internal mixer. The catalytic activity of the Zn-ions (originating from the structural silica) towards the oxirane group (diglycidyl ether of bisphenol-A (DGEBA): encapsulating agent) was assessed by infrared spectroscopy. Two composites, each with a filler content of $2.5 wt\%$ were developed. The first one was obtained by melt blending the Zn-ion coated structural silica with LDPE in a co-rotating sigma internal mixer. The second one was obtained by melt blending the same LDPE, but with DGEBA encapsulated Zn-ion coated structural silica. Epoxy resin encapsulation of the Zn-ion coated structural silica resulted in its having good interfacial adhesion and a homogeneous dispersion in the polymer matrix. Furthermore, the encapsulation of epoxy resin over the Zn-ion coated structural silica showed improvements in both the mechanical and thermal properties, viz. a $33\%$ increase in the elastic modulus and a rise in the onset degradation temperature from 355 to $371^{\circ}C$, in comparison to the Zn-ion coated structural silica.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.176-176
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• 2010

One of the critical issues for applications of flexible organic thin film transistors (OTFTs) for flexible electronic systems is the electrical stabilities of the OTFT devices, including variation of the current on/off ratio (Ion/Ioff), leakage current, threshold voltage, and hysteresis under repetitive mechanical deformation. In particular, repetitive mechanical deformation accelerates the degradation of device performance at the ambient environment. In this work, electrical stability of the pentacene organic thin film transistors (OTFTs) employing multi-stack hybrid encapsulation layers was investigated under mechanical cyclic bending. Flexible bottom-gated pentacene-based OTFTs fabricated on flexible polyimide substrate with poly-4-vinyl phenol (PVP) dielectric as a gate dielectric were encapsulated by the plasma-deposited organic layer and atomic-layer-deposited inorganic layer. For cyclic bending experiment of flexible OTFTs, the devices were cyclically bent up to 105 times with 5mm bending radius. In the most of the devices after 105 times of bending cycles, the off-current of the OTFT with no encapsulation layers was quickly increased due to increases in the conductivity of the pentacene caused by doping effects from $O_2$ and $H_2O$ in the atmosphere, which leads to decrease in the Ion/Ioff and increase in the hysteresis. With encapsulation layers, however, the electrical stabilities of the OTFTs were improved significantly. In particular, the OTFTs with multi-stack hybrid encapsulation layer showed the best electrical stabilities up to the bending cycles of $10^5$ times compared to the devices with single organic encapsulation layer. Changes in electrical properties of cyclically bent OTFTs with encapsulation layers will be discussed in detail.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.137-142
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• 2011

Individual solar cells must be connected together to give the appropriate current and voltage levels and they must also be protected from damage by the environment. [1] PV module consists of a glass/ polymer encapsulation/ solar cell string/ polymer encapsulation/ back sheet. Usually, encapsulation materials is used EVA(ethylene vinyl acetate), PVB(polyvinyl butyral), PO(polyolefin)sheet. This study is about fabrication of module using silicone material instead of above them. We got to know advantage that is fabrication time and efficiency of modules.

• Applied Microscopy
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• v.52
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• pp.7.1-7.6
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• 2022

The process of encapsulating cobalt nanoparticles using a graphene layer is mainly direct pyrolysis. The encapsulation structure of hybrids prepared in this way improves the catalyst stability, which greatly reduces the leaching of non-metals and prevents metal nanoparticles from growing beyond a certain size. In this study, cobalt particles surrounded by graphene layers were formed by increasing the temperature in a transmission electron microscope, and they were analyzed using scanning transmission electron microscopy (STEM). Synthesized cobalt hydroxide nanosheets were used to obtain cobalt particles using an in-situ heating holder inside a TEM column. The cobalt nanoparticles are surrounded by layers of graphene, and the number of layers increases as the temperature increases. The interlayer spacing of the graphene layers was also investigated using atomic imaging. The success achieved in the encapsulation of metallic nanoparticles in graphene layers paves the way for the design of highly active and reusable heterogeneous catalysts for more challenging molecules.

• Journal of the Korean institute of surface engineering
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• v.46 no.3
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• pp.111-115
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• 2013

To study the encapsulation method for large-area organic light emitting devices (OLEDs), OLED of ITO / 2-TNATA / NPB / $Alq_3$:Rubrene / $Alq_3$ / LiF / Al structure was fabricated, which on $Alq_3$/LiF/Al as protective layer of OLED was deposited to protect the damage of OLED, and subsequently it was encapsulated using attaching film and flat glass. The current density and luminance of encapsulated OLED using attaching film and flat glass has similar characteristics compared with non-encapsulated OLED when thickness of Al as a protective layer was 1200 nm, otherwise power efficiency of encapsulated OLED was better than non-encapsulated OLED. Encapsulation process using attaching film and flat glass did not have any effects on the emission spectrum and the Commission International de L'Eclairage (CIE) coordinate. The lifetime of encapsulated OLED using attaching film and flat glass was 287 hours in 1200 nm Al thickness, which was increased according to thickness of Al protective layer, and was improved 54% compared with 186 hours in same Al thickness, lifetime of encapsulated OLED using epoxy and flat glass. As a result, it showed the improved efficiency and the long lifetime, because the encapsulation method using attaching film and flat glass could minimize the impact on OLED caused through UV hardening process in case of glass encapsulation using epoxy.