Yoshio Umayahara

A LTCC Material with Low Temperature Coefficient of Resonance Frequency

For high frequency packaging applications, LTCC materials are required to have a low loss tangent to reduce the total microwave loss. For multi-layered ceramic devices with embedded passive components, besides a loss tangent, a small temperature coefficient of resonance frequency (TCF) is an important factor. To meet these demands, we developed a new LTCC material with a smaller TCF, less than +/-3ppm/oC, and a low loss tangent, 0.0012 at 15GHz. We designed the glass composition to precipitate two low-loss crystal phases during firing at 900 oC. One phase has a plus TCF and the other phase has a minus TCF. We also controlled the amount of the two crystal phases, so these crystal phases and the fixed amount of alumina filler make the sum of TCF for the LTCC material close to zero.