The effect of heat-treatment on the suspension stability and gelation behavior of Li2O-BaO-Al2O3-SiO2-CaO(LBASC)

The effect of surface-passivation of glass particulates on the gelation behavior of CaZrO3/Li2O-B2O3-Al2O3-SiO2-CaO (LBASC) glass suspension was investigated in a system where organic solvents, a dispersant, and a binder were used as processing additives in the fabrication of Cu-multilayered ceramic capacitors (Cu-MLCCs) for a radio frequency (RF) module. The gelation behavior of the suspension showing the time dependency occurred due to the reaction and linkage between the hydroxyl groups in PVB and the boron ions that had dissolved from the glass surface. In order to reduce the dissolution of boron ions from the glass surface, the glass particulates were heat-treated at 500 degrees C. The dissolution of ions from the raw glass particulates and heat-treated glass particulates was compared using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and X-ray photoelectron spectroscopy (XPS). It was found that the viscosity of the suspension prepared with the heat-treated glass was reduced compared to the viscosity of the suspension with the raw glass particulates, which indicated an alleviation of gel formation by heat-treatment. Microstructural observations also revealed that the sheet prepared from the suspension with the heat-treated glass particulates showed a more homogeneous green microstructure and higher green density than the gelled sheet prepared from the raw glass particulates. (c) 2005 Elsevier B.V. All rights reserved.