Modification of tape casting slurry via effective plasticization by butyl benzyl phthalate of CaO–SiO₂–B₂O₃ glass–ceramics

This present work aimed to attain a high-performance tape for LTCC application by using butyl benzyl phthalate as plasticizer in tape casting slurry of CaO–SiO₂–B₂O₃ glass–ceramics. The plasticizing mechanism of butyl benzyl phthalate in suspensions was demonstrated in depth. Dried droplets of binder were prepared to preliminarily judge the compatibility of binder and plasticizer, and the optimal additive amount was determined by rheological characteristic. In addition, a series of qualitative and quantitative methods were carried out to assess the tensile strength and elongation of green tapes, microwave properties and densification of sintered bodies. The experimental results revealed that when the addition of BBP was up to 45 wt%, tape casting slurries had the optimal fluidity and green tapes obtained the excellent performance with density at 1.65 g/cm³, tensile strength at 1.43 MPa and elongation at 13.4%. Meanwhile, sintered bodies fired at 850 °C achieved the highest density at 2.42 g/cm³ with ε_r = 5.94 and tanδ = 10 × 10⁻⁴ at 10 GHz.