• Korean Journal of Materials Research
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• v.14 no.10
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• pp.731-736
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• 2004

Herein, we report on the co-firing of a low-K wiring substrate and a middle-K functional substrate in LTCC. Firstly, we researched the sintering behavior and dielectric properties of the low-k wiring substrate comprised by alumina and glass frit with ${\varepsilon}_r$, of $\sim7$ and the middle-k functional substrate comprised by $Ba_{5}Nb_{4}O_{15}$ and glass frit with ${\varepsilon}_r$, of $20\sim30$. The warpage and delamination between the hetero layers of the low-K and the middle-K composition were also studied. In particular, physical matching of the hetero layers could be possible by adjusting of the sintering properties of the composition. We observed that an introduction of the glass frit to the low- and middle-K substrate gives rise to a minimization of an effect given by separation of the hetero layers, and modification of the fraction of the glass frit accompanied by a variation of the composition could control the sintering behavior and its beginning temperature. In the case of co-firing of the L03 as the low-K wiring substrate composition and the M03 as the middle-K functional substrate composition at $875^{\circ}C$, we could fabricate a desirable structure of hetero layers without any kinds of structural defects such as separation, warpage, delamination, pore trap, etc. We suppose that the co-firing techniques described in this study would provide a helpful method to fabricate a LTCC multi-functional for the next generation.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.11a
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• pp.129-133
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.75.2-75
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.107.1-107
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.162-162
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• 2002

• Journal of the Korean Ceramic Society
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• v.46 no.3
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• pp.313-316
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• 2009

A zinc borosilicate glass having a low softening temperature of $490^{\circ}C$ has been investigated as a protective layer for Ag patterns against chemical reactions with a $I^-/I_3^-$ electrolyte in dye-sensitized solar cells (DSSCs). A thick glass layer was prepared by the typical screen printing and firing processes to obtain a final thickness of ${\sim}5{\mu}m$. The chemical leaching performance of the glass layer in the electrolyte revealed that the reactive Ag pattern can be significantly protected by utilizing the low softening protective layer. The electrical resistance of the FTO-coated glass substrate was effectively maintained at a low value of ${\sim}27{\Omega}$ as long as the glass layer was well densified at a sufficiently high temperature of ${\sim}520^{\circ}C$. The transmittance of the layer was near 60%, depending on the firing temperature of the glass layer.

• Korean Journal of Materials Research
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• v.12 no.8
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• pp.595-599
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• 2002

A homogeneous and stable, amorphous-type, anorthite (CaO $Al_2$$O_3$ $2SiO_2$)powder was synthesized by an organic-inorganic steric entrapment route. Polyvinyl alcohol ( PVA) was used as an organic carrier for the precursor ceramic gel. The PVA content, its degree of polymerization and type of silica sol had a significant influence on the calcination and crystallization behavior of the precursors. For densifiction and crystallization at low temperature, porous and soft, amorphous-type anorthite powder was planetary milled for 20h. The milled powder crystallized to stable anorthite phase and densified to a relative density of 94% below $1000^{\circ}C$. In the development of crystalline phases of the planetary milled powder, omisteinbergite phase was unusually observed at $900^{\circ}C$, and then anorthite was observed at $950^{\circ}C$. The sintered anorthite had a thermal expansion coefficient of $4.6$\times$10^{-6}$ /$^{\circ}C$ and a dielectric constant of 7.5 at 1 MHz. Finally, the anorthite synthesized by the new process is expected to be an useful material for low-firing ceramic substrate.

• Journal of Conservation Science
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• v.38 no.4
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• pp.301-313
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• 2022

We made a Korean white porcelain or Joseon Baekja jar and based on the raw materials used and reproductions of each stage, we aimed to compare and analyze the physicochemical changes of the raw materials such as clay at each manufacturing stage, as well as identify the characteristics and correlations. Although the basic main components of clay and glaze material are similar, their texture becomes denser in the process of bisque firing pottery (Chobeol-pyeon) and glaze firing pottery (Jaebeol-pyeon), and we confirmed that in addition to the tendency of increasing vitrification, low-temperature minerals such as mica and illite gradually disappeared, while high-temperature minerals such as cristobalite were newly created. This phenomenon has also been verified by the rapid decrease in absorption rate while the change in specific gravity was small. In addition, the color was greatly affected by the firing atmosphere, and the yellow-red chromaticity of the raw materials was higher during bisque firing but showed a rapidly decreasing characteristic during glaze firing. The value of magnetic susceptibility, which is related to iron (Fe) component, showed a tendency to decrease in glaze firing pottery. CT images were confirmed as a method that can indirectly estimate the change in the material properties of the object step-by-step for the entire object. In conclusion, the study of manufacturing stages of reproduction can provide basic data for scientific research on the estimation of porcelain and pottery making technology and changes in raw materials.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.433-440
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• 2000

The influence of combustion air at temperatures on nitric oxide emission was studied. The nitric oxide emission generally increases with a rise in the temperature of the combustion air. However, if combustion products for dilution of fuel or combustion air are used before the combustion reaction, then the nitric oxide emission can be reduced even when highly preheated air for combustion air is used. Combustion in low oxygen concentrations flattens the firing mode, resulting in a uniform reaction, and, thus, low nitric oxide emission can be achieved.

• Journal of the Korean Ceramic Society
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• v.18 no.3
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• pp.192-200
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• 1981

This study deals with the low temperature ($25^{\circ}C$-$600^{\circ}C$) properties of Kaolin-Phosphate-water systems. Phosphoric acid, mono aluminum phosphate, mono ammonium phosphate, the mixture of phosphoric acid and mono aluminum phosphate, and the mixture of phosphoric acid and mono ammonium phosphate were used to characterize the M.O.R. of the systems with to quantity of phosphates, curing time, and firing temperature. Firing shrinkage, viscosity, surface tension, DTA, TGA, and X-ray diffraction patterns were also measured in order to investigated the factors of strengthening. The results of this study were summarized as follows: 1. The M.O.R. of kaolin-phosphate systems were stronger than that of Kaolin-water system at room temperature or low temperature($25^{\circ}C$-$600^{\circ}C$). Though it was increased according to the longer curing time, the higher temperature, and the more addition of phosphate, the M.O.R. were decreased in the case of 10 wt% phosphate addition in the system of phosphoric acid, mono aluminum phosphate and phosphoric acid-mono aluminum phosphate. 2. When the concentration of Phosphate was at 4 wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid was strongest among the specimens in added to the others phosphates. Whereas, when the concentration of phosphate was above 6wt%, the M.O.R. of specimen cured at $25^{\circ}C$ and added to the phosphoric acid mono ammonium phosphate system cured at $25^{\circ}C$ was the strongest. 3. The M.O.R. of the specimen heated, in the temperature range of 15$0^{\circ}C$-1$600^{\circ}C$, and added to the mixture of phosphoric acid-mono aluminum phosphate system or phosphoric acid-mono ammonium phosphate system was stronger than that of specimen added to Phosphoric acid, mono-aluminum Phosphate or mono-ammonium phosphate alone. 4. The bonding force of phosphate binders was more closely related to surface tension than viscosity and it tended to be inversely proportional to surface tension. The bonding force after heating treatment seemed to be caused by the change of structure of phosphate according to heating.