High dielectric constant materials development for LTCC

As wireless systems require more functions within the package, device miniaturization will motivate a search for new dielectric materials with a range of dielectric constants (k). New dielectric materials must be co-processed with commercially available low temperature co-fire ceramic (LTCC) tape and with silver. Ternary compounds, such as Bi₂O₃-ZnO-Ta₂O₅ and Bi₂O₃-ZnO-Nb₂O₅, are interesting for high frequency filters and capacitors because of their low process temperatures, temperature stable dielectric properties, and low dielectric loss. Two primary phases have been explored which have significant dielectric property differences. The α phase has high permittivity (70<k<150) and a negative temperature coefficient of dielectric constant. The β phase has a lower permittivity (60<k<80) and has a positive temperature coefficient of dielectric constant. Composites of α and β phases are useful for temperature stable dielectric materials. A standard procedure is outlined in which the properties of promising dielectric materials are characterized, then the compatibility is tested in resonant stripline devices, and finally a prototype low-pass filter is fabricated.