A Novel K7/K50 Co-Fireable PME LTCC Dielectric System for Microwave Filter Application

With an increased number of wireless applications at microwave frequencies, a frequency spectrum became crowded. Microwave filters, as an essential part of any microwave circuitries, enable selection of target wavelengths for further processing. Performance of filters strongly depend on properties of dielectrics materials used for filter construction. The choice of dielectric materials defines center frequency of the filter, insertion loss, filter selectivity, and other key parameters. As an example, lower losses of the dielectric enable higher filter quality factor which translates to lower passband insertion loss and sharper transitions from passband to stopband. Another level of improvements can be achieved when a filter simultaneously utilizes several dielectrics having different dielectric constant. This design approach assists with optimization of each section of the filter and promotes better microwave performance with higher volumetric efficiency. Low temperature co-fired ceramic (LTCC) has become an enabling technology for a variety of wireless applications at microwave frequencies as it provides cost-effective and efficient solution suitable for high-volume production. To meet the market demands for higher performance and lower cost, Vibrantz has developed both low-K (K~7) and high-K (K~50) co-fireable low loss LTCC dielectrics, MW7U and MW50U. Both LTCC dielectrics are fully compatible between each other and with 100% Ag electrodes, can be fired at 900°C for 30 minutes, and offer a set of excellent dielectric properties: MW7U: K=7.0; Q=1,780; Q*f=27,790GHz; Τf=-27.0ppm/C; MOR=250MPa. MW50U: K=51.8; Q=1,650; Q*f=10,560GHz; Τf=204.0ppm/C; MOR=170MPa. In addition, MW7U and MW50U offer high resistance to chemical attacks during plating which is the critical parameter for a chip component manufacturing. Properties of both LTCC dielectrics are comprehensively evaluated and considered for microwave filter applications.