Shin Kim

Various Filler Added CaO-Al 2 O 3 -SiO 2 Glass Composites for LTCC Substrate Applications

Influences of ceramic filler types and dose on the sintering, phase evolution, and dielectric properties of ceramic/CaO-Al₂O₃-SiO₂ glass composites were investigated. All of the specimens were sintered at 900℃ for 2 h, which conditions are required by the lowtemperature co-firing ceramic (LTCC) technology. Ceramic fillers of Al₂O₃, SiO₂, kaolin, and wollastonite were used. The addition of Al₂O₃ filler yielded the crystalline phases of alumina and wollastonite, and the densification over 95% of the relative density was achieved up to 50 wt% addition of the filler. For the cases of the fillers of SiO₂, kaolin, and wollastonite, crystalline phases of quartz, mullite, and wollastonite formed, while the densification decreased monotonically with the filler addition. In overall, all the investigated fillers with 10 wt% addition resulted in a reasonable sintering (over 95 %) and low dielectric constants (less than 6), demonstrating the feasibility of the investigated composites for application to a LTCC substrate material with a low dielectric constant.

Properties of Low Temperature Sintered Porous Ceramics from Alumina-Zinc Borosilicate Glass

The low-temperature preparation of porous ceramics was carried out using mixtures of alumina-zinc borosilicate (ZBS) glass. The compositions of alumina-ZBS glass mixture with PMMA pore-former were unfortunately densified. Because PMMA was evaporated below the softening point of ZBS glass (588℃), the densification through the pore-filling caused by the capillary force might occur. Howerver, those with carbon possessed pores where carbon was evaporated above the softening point. The porous ceramic having 35% porosity was successively fabricated by the low-temperature sintering process below 900℃ using 45 vol% of alumina, 45 vol% ZBS of glass, and 10 vol% of carbon as starting materials.

Densification and Dielectric Properties of Glass/Ceramic Composites Sintered with Various Borosilicate Glass

Al2O3 and TiO2 were sintered with three types (lead, zinc, bismuth) of borosilicate glass. Their microwave dielectric properties and sintering behavior were investigated as functions of glass type, glass addition (10~50 vol%) and sintering temperature (600~950°C for 2 hrs). Sintering characteristics were well described in terms of softening temperature, second phase, and excessive liquid. In particular, Bi2O3 addition to the glass enhanced reaction with Al2O3 and TiO2 to form liquid phase and second phase. In terms of dielectric properties glass/Al2O3 composites for application to substrates while glass/TiO2 composites for filters were shown to be appropriate.

Thermal and Dielectric Properties of LiF-Doped MgO Ceramics

Sintering, microstructure, thermal conductivity and microwave dielectric properties of xLiF-(1-x)MgO ceramics (x

Minimizing the Water Leaching of Zincborate Glass by La₂O₃ Addition for LTCC Applications

A series of La₂O₃-added zincborosilicate glasses was fabricated by systematically varying La₂O₃ addition up to 15 mol% under the constraint of a ZnO:B₂O₃ ratio of 1 : 2. The degree of water leaching after ball milling of the prepared glasses in water medium was relatively quantified by the change in zinc peak intensity in energy dispersive spectroscopy. 8mol% of La₂O₃ was the most efficient addition in inhibiting the glass leaching by water. The role of La₂O₃ in inhibiting the leaching was explained in terms of change of structural units in the glass network. When the optimum 8 mol% La₂O₃-added ZnO-B₂O₃ glass was used as sintering aid for Al₂O₃, the fabricated alumina-glass composite at 875℃ demonstrated dielectric constant of 6.11 and quality factor of 15470 ㎓, indicating the potential of leaching-minimized La₂O₃-ZnO-B₂O₃ glass for application to low temperature co-fir-ing ceramic technology.

Low Temperature Sintering and Dielectric Properties of BiNbO 4 and ZnNb 2 O 6 Ceramics with Zinc Borosilicate Glass

Low temperature sintering behavior and microwave dielectric properties of the and the borosilicate glass(ZBS) systems were investigated with a view to applying the composition to LTCC technology. The addition of wt% ZBS in both systems ensured successful sintering below . For the system, the sintering was completed when 15 wt% ZBS was added whereas 25 wt% ZBS was necessary for the system. Secondary phase was not observed in the system but a small amount of with the willemite structure as the secondary phase was observed in the system. In terms of dielectric properties, the application of the and the systems sintered at to LTCC were shown to be appropriate; wt% ZBS(

Low-temperature preparation and microwave dielectric properties of ZBS glass-Al2O3 composites

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