As the operating environment in semiconductor processes becomes demanding, research is being conducted to manufacture dense alumina substrates without defects after sintering to ensure high durability of electrostatic chucks, which are critical components in semiconductor equipment. Therefore, in this study, in order to manufacture green sheets with a high filling ratio for implementing a high-density substrate, alumina powders with average particle sizes of 2.07 μm (L) and 0.37 μm (S) were mixed in ratios of 9:1, 8:2, 7:3, and 6:4, respectively, and green sheets were manufactured and the filling ratio and sintering behavior were observed. Green sheets were fabricated by preparing a slurry using organic materials in Al₂O₃ powders of different particle sizes. The packing density of the green sheet mixed with L and S alumina powders with different average particle sizes in a ratio of 7:3 before and after binder burn-out showed the highest values of 3.19 g/cm³ and 2.87 g/cm³, respectively. As a result of observing the sintered density based on the mixing ratio of alumina powders revealed that the alumina sheet mixed at a 6:4 ratio of L and S powders, sintered at 1,700℃, exhibited the best sintering characteristics with a density of 3.96 g/cm³.

Hole explosion behaviors were observed during drilling fine holes with laser beam on the LTCC green bar of 320 ㎛ thick after lamination of green sheets prepared by tape casting of thick film process. The incidence of these hole explosions was inversely proportional to hole sizes. The incidence of hole explosion was 20 % number of hole with the size of 60 ㎛ exploded for the UV radiation, while the explosion did not appear for hole sizes over 100 ㎛. To prevent hole explosion behavior during laser-drilling of fine holes, carbon black powder was added as an additive in the LTCC composition, which has superior thermal durability. As a consequence, hole explosion rate was suppressed to 0.8 % for the hole size of 50 ㎛ green sheet with the carbon black amount of 10 weight % and the laser power of 3 watt. Added carbon is thought to reduce the heat-affected region during laser drilling.

It is necessary for ferrite sheets to be fabricated with high packing density for excellent electrical properties and high strength. In this study, the relationship between the warpage and the packing density of ferrite green sheet, was investigated with amount variation of organic additives. With 0.4 wt% of dispersant, the packing density was about 48% and warpage appeared 0.5~1.3 ㎜ high. With 1.4 wt% of dispersant, the packing density increased up to 57% and warpage appeared 0.8~2.1 ㎜ high. With high packing density, warpage appeared along the edges of specimen, while with low packing density, deformation appeared over whole specimen inhomogeneously. It is thought that inhomogeneous deformation after sintering came from the inhomogeneity in green sheet prepared with badly dispersed slurry. With good homogeneity in green sheet from well-dispersed slurry, isotropic shrinkage is thought to have occurred along the distance from center to edges of specimen during sintering.

The properties of LTCC green sheets formed by the MLS-22 powder of NEG Inc. were investigated for acrylic binders with different PVB and Tg in the variation of temperature. The elongation of the green sheets showed large variation depending on the temperature, and was rapidly decreased near the Tg of the sheets. With the increase of the ratio of plasticizer/binder (P/B), large elongation of the sheets was observed due to the decrease of the Tg. In the stacking process of the multilayer ceramic, the optimal control of the temperature is highly required depending on the Tg of the binder and the ratio of P/Buniform coating.

The properties of green sheet were investigated in order to understanding an effects of organic solvent mixture ratio for solid oxide fuel cells fabrication, The purpose of this work is to optimize the slurry condition using the design of experiment to improve green sheet properties. The elongation increased with increasing amount of binder and solvent. With increasing amount of solvent, the air permeability increased but the tensile strength decreased. The best properties of the green sheet appeared amount of the binder 17 wt%, solvent 35 wt% and powder 48 wt%. The optimum condition of green and sintered density for solid oxide fuel cells fabrication was obtained in the sample pressured at 800kgf/㎠.