Dynamic Visco-elasticity and Adhesion Properties of Ceramic Green Sheets

Abstract

Adhesive properties of alumina green sheets containing Poly vinyl butyral (PVB) and Dioctyl phthalate (DOP) were investigated. 10wt% of PVB was added while DOP was varied between 0 and 6wt%. By the dynamic visco-elasticity measurement (1 and 10Hz), the glass transition temperature (Tg) of green sheet was found to be 4.7-14.4K higher than that of binder film at the same PVB/DOP ratio. Apparent Tg of DOP was estimated to be 204K through the measurements of Tg of binder films with various PVB/DOP ratios. Adhesive properties of green sheet appeared at a temperature 30 to 40K higher than Tg of the green sheet. Scanning electron microscope observation and ATR-FTIR analysis showed that PVB and DOP were distributed on the side in contact with a PET film at a larger fraction that the opposite side. This is caused by the difference in the wetting characteristics between PVB and PET film when they are wet with DOP. In laminating process of green sheet, the adhesion force may occur by two steps. First the surface of green sheet is wet with DOP and then the adhesion force at the laminating interface grows because of the formation of binder chains between the ceramic particles.