Effect of particle size in slurry manufacturing for green sheet of lead-free transparent dielectrics

Abstract

The dispersion characteristics of the slurries according to the particle size (0.7 mu m, 5 mu m and 10 mu m) of the lead(Pb)-free frit as a raw material were studied in order to aid in the manufacture of a green sheet for the transparent dielectric layers using the tape casting method. Effect of solvents and dispersants on the slurry formation was investigated by comparing the sedimentation height according to the particle size of the frit. Overall observations about precipitation and viscosity have been performed to establish the suitable manufacturing of slurry and the optimum working condition of the green sheet. When the powder of lead-free transparent dielectric frit was dispersed in methyl alcohol, it was found that polyethylene glycol was the most suitable among several dispersants. Higher dispersion stability was shown at 2.0 wt% addition for a particle size of 0.7 mu m, 1.5 wt% for 5 mu m, and 1 wt% for 10 mu m, which can be explained by a steric stabilization mechanism. The smaller particle size is more recommendable for dispersion based on steric stabilization, and increases the effective solid contact rate per unit volume, leading to a higher transmittance and voltage withstand property.