Effects of BaTi₄O₉ Concentration on Dielectric Constants of the Polyetherimide/BaTi₄O₉ Composites

In this chapter, the poly(ether imide) (PEI)/BaTi₄O₉ (BT4) composites were investigated for the applications of the high dielectric constant embedded capacitors or flexible organic substrates. BT4 ceramic was sintered at 1,275°C and ground into microscale power. After that, BT4 ceramic power was mixed with PEI to form PEI/BT4 composites, the effects of the concentration of BT4 filler on the physical and dielectric properties were developed. Thermogravimetric analysis (TGA) was used to determine the weight loss, thermal degradation temperature (T _d), and endothermic-exothermic peak of the PEI/BT4 composites. The Lichtenecker mixing rule was used to predict the variations of dielectric constants of the PEI/BT4 composites, and the mixing rule would fit the measured results. The dielectric constants of the PEI/BT4 composites with various concentrations (0–70 wt%) of BT4 filler were measured, and the dielectric constants were almost unchanged as the measured frequency increased, because the PEI was a nonpolarized material. This research proved that we could investigate the PEI/BT4 composites with stable frequency-dependent properties.