Epoxy/BaTiO3 (SrTiO3) composite films for high dielectric constant and low tolerance embedded capacitors fabrication in organic substrates

Epoxy/BaTiO₃ composite embedded capacitor films (ECFs) were newly designed for high dielectric constant and low tolerance (less than ±5%) embedded capacitor fabrication in organic substrates. In terms of material formulation, ECFs were composed of specially formulated epoxy resin and latent curing agent. And in terms of coating process, a comma roll coating method was used for a uniform film thickness over large area. Dielectric constants of BaTiO₃ & SrTiO₃ composite ECFs were measured with MIM (metal-insulator-metal) capacitors at 100 kHz using LCR meter. Dielectric constants of BaTiO₃ ECFs were larger than these of SrTiO₃ ECFs, due to the difference of permittivity of BaTiO₃ and SrTiO₃ particles. Dielectric constants of BaTiO-, & SrTiO₃ ECFs at high frequency range (0.5∼10GHz) were measured using a cavity resonance method. For both powders, dielectric constants in high frequency range were about 3/4 of the dielectric constants at 1 MHz. This difference is mainly due to the decrease of dielectric constant of epoxy matrix. For BaTiO₃ ECFs, there was a dielectric relaxation at 5∼9GHz presumably due to the polarization mode change of BaTiO₃ powder. However in case of SrTiO₃ ECFs, there was no relaxation up to 10GHz.