Preparation and Characterization of Microwave Dielectric Ceramics for LTCC Passive Integration

Preparation and Characterization of Microwave Dielectric Ceramics for LTCC Passive Integration Applications Prof. Zhenxing Yue, State Key Laboratory of New Ceramics and Fine Processing, Dept. of Materials Science & Engineering, Tsinghua University, Beijing 100084, China. Email: [email protected]

In the recent years, microwave dielectric ceramics have received much attention because of the rapid growth of wireless communication industry. A large number of ceramic dielectric materials have been developed. A high dielectric constant, a high quality factor and a near-zero temperature coefficient of resonant frequency are three key properties required for microwave resonator materials [1]. The development of low-temperature co-fired ceramics (LTCC) has been stimulated by the benefits offered for the fabrication of miniature multilayer devices and for high level of passive integration involving the co-firing of dielectric and highly conductive metal, such as silver and copper and various LTCC materials have been explored [2]. However, most of commercial microwave dielectric materials available require high sintering temperature. Adding the low melting point oxides such as B2O3, V2O5, is widely used to reduce the sintering temperature of commercially developed dielectric ceramics. However, these low melting oxides may have a detrimental effect on the microwave dielectric properties due to introducing glassy phase. In this project, the glass-free LTCC materials with low dielectric loss and near- zero temperature coefficient of the resonant frequency will be developed via a materials composite route. The niobates, tungstates or vanadates were reported to have excellent dielectric properties and low sintering temperatures. The composite ceramics having low sintering temperatures and near-zero temperature coefficients might be obtained by combining niobates with tungstates or vanadates [3, 4]. In this project, the novel glass-free LTCC materials will be prepared and the dielectric properties will be measured at microwave frequency. The structure and dielectric properties will be also investigated.

Research Tasks:

(1) Study the basic knowledge on electronic ceramics, especially on microwave dielectric ceramics; (2) Prepare low-temperature co-fired dielectric ceramics with low microwave dielectric loss; (3) Study the measurement techniques for the dielectric properties of materials at microwave frequency; (4) Characterize the structure and properties of the prepared microwave dielectric ceramics.

References

1. W. Wersing, Microwave ceramics for resonators and filters, Curr. Opin. Solid State Mat. Sci. 1,715-31 (1996) 2. M. T. Sebastian and H. Jantunen, Low loss dielectric materials for LTCC applications: a review, Int. Mat. Rev., 53, 57-90 (2008) 3. Hao Zhuang, Zhenxing Yue, Fei Zhao, Longtu Li, Low-temperature sintering and

microwave dielectric properties of Ba5Nb4O15-BaWO4 composite ceramics for LTCC applications, J. Am. Ceram. Soc. 91, 3275-3279 (2008) 4. Hao Zhuang, Zhenxing Yue, Siqin Meng, Fei Zhao, Longtu Li, Low-temperature

sintering and microwave dielectric properties of Ba3(VO4)2-BaWO4 ceramic composites, J. Am. Ceram. Soc. 91,3738-3741 (2008)