| The development of microwave technology is continuously pushing mobile communication equipments and portable terminals to micromation, complex, multilayer and modularization. LTCC (Low Temperature Co-fired Ceramic) technique is the best method to achieve the aim. To match the LTCC technique and the request of high frequency components, microwave dielectric ceramics are developing to high frequency and low singtering temperature.CaSiO3 system ceramic is an excellent low dielectric constant and high frequency microwave dielectric material. But its sintering temperature is so high that it cannot be sintered under 1000℃ with low melting point electrode materials like Ag, Cu etc. Presently investigations about this material are mainly via glass-ceramic technique to decrease the sintering temperature and the dielectric loss is high. For the first time, this investigation manufacture a CaSiO 3 system low dielectric and high frequency microwave dielectric ceramic via tape casting with basic material altered and additives doped.1.Harmonize the microwave dielectric properties of CaSiO3 ceramic. This investigation use Mg2 + and Zn2 +replace Ca2+ to alter the basic material. The investigation indicate that the Q f value of CMS ceramic is about two times of the CZS ceramic's. (Ca0.7Mg0.3) SiO3 sintered at 1280℃ has an excellent dielectric property, εr=7.20, Q f=20978GHz (8GHz) It's the best basic material for low temperature sintering investigation.2. Use Li2O and Bi2O3 as complex additives to decrease the sintering temperature of (Ca0.7Mg0.3) SiO3 and harmonize its microwave dielectric properties. The result indicate that addetives can accelerate (Ca0.7Mg0.3) SiO3 ceramic to form CaMgSi2O6 and CaSiO3 which have good dielectric properties. lwt%Li2O and 6wt%Bi2O3 doped (Ca0.7Mg0.3) SiO3 can be sintered at 920℃ and has the best dielectric properties of εr=7. 61, Q f>15000GHz (8GHz), but the τ(-41ppm/℃) is too high.3. Optimize the dielectric properties of low temperature sintered microwave dielectric ceramics. Use CaTiO3 to adjust the frequency temperatrue coefficient. The result indicate that 14wt% doped (Ca0.7Mg0.3) SiO3 ceramic sintered at 900℃ has an excellent microwave dielectric property as 9. 42, Q f>11000GHz (8GHz), +3.5ppm/℃The properties of this material is keeping ahead and fill the blank of low dielectric, high frequency and low temperature sintered microwave dielectric ceramics inland. Batch production proved that this ceramic suits LTCC technique and can be used to produce minitype microwave frequecy components like multilayer antennas, balance-imbalance conversionars and low pass filter ect. |
