LTCC滤波器用MgO-B2O3二元体系低介、高Q微波介电材料的成分设计、缺陷调控与性能研究

High frequency of modern mobile communication technology requires the corresponding microwave dielectric ceramics should have lower permittivity. However, so far commercial low temperature co-fired ceramics (LTCC) materials with low permittivity contain excess glass phase, which induces the problems with casting difficulties and high dielectric loss. In this project, novel MgO-B2O3 based binary system with low permittivity and small dielectric loss will be designed and prepared. Firstly, the intrinsic dielectric properties of ceramics will be studied by the far infrared reflectance spectroscopy and the first principle calculation, and the origin of dielectric loss will be revealed. Furthermore, small amount of BaCu(B2O5) powders will be added to reduce the sintering temperature of ceramics. The volatilization of B2O3, characteristics of grain boundary and vacancy will be systematically investigated. The intrinsic relationship between the above factors and microwave dielectric properties of ceramics will be discussed, and the microwave dielectric performance of ceramics will be optimized by controlling the structure and defect. The inherent mechanism of impacts between the chemical composition, microstructure and properties about the bending strength and resistance to corrosion characteristics of electroplating will be revealed. Finally, novel low permittivity and small dielectric loss MgO-B2O3-based LTCC materials with excellent performance will be obtained. The implementation of this project will not only improve the principle and methods of performance control for LTCC microwave dielectric materials with low permittivity, but also provide a theoretical and experimental reference for designing similar microwave dielectric materials.

现代通讯技术的高频化要求相应的微波介电陶瓷必须具有更低的介电常数，但是目前商用低介电常数LTCC材料中玻璃相成分过多，存在流延成型困难、介电损耗大等缺点。本项目拟设计制备新型MgO-B2O3基二元体系低介电常数、低损耗LTCC微波介电陶瓷。首先，通过第一性原理计算和远红外反射光谱研究该类陶瓷材料的本征介电特性，揭示其介电损耗的起源。在此基础上，添加少量BaCu(B2O5)陶瓷粉体来降低材料的烧结温度，研究B2O3的挥发、晶界特性、空位等缺陷，揭示上述因素与材料微波介电特性之间的内在关系，通过结构与缺陷调控实现对该类陶瓷介电性能的优化。探讨化学组分、微结构对陶瓷抗弯强度和电镀腐蚀性能的内在影响机理，以期获得性能优异的新型MgO-B2O3基低介低损LTCC微波介电陶瓷。本项目的顺利实施，有助于进一步完善低介LTCC材料性能调控的原理和方法，为类似微波介电材料的科学裁剪提供实验与理论借鉴。

现代通讯技术的高频化要求相应的微波介电陶瓷必须具有更低的介电常数，但是目前商用低介电常数LTCC材料中玻璃相成分过多，存在流延成型困难、介电损耗大等缺点。为了解决这一关键问题，本项目设计制备了系列新型MgO-B2O3基二元体系低介电常数、低损耗LTCC微波介电陶瓷，系统研究了制备工艺对陶瓷材料组成、结构以及微波介电性能等的影响。在此基础上，添加少量BaCu(B2O5)[或BaCu(B2O5)+H3BO3]低熔点粉体来降低材料的烧结温度，系统研究了B2O3的挥发、晶界特性、空位等缺陷，揭示了上述因素与材料微波介电特性之间的内在关系，通过结构与缺陷调控实现了对该类陶瓷介电性能的优化，获得了一系列性能优异的新型MgO-xB2O3-yBaCu(B2O5)、MgO-2B2O3-xwt%BaCu(B2O5)-ywt%H3BO3以及3MgO-B2O3-xwt%BaCu(B2O5)-ywt%H3BO3等低介低损LTCC微波介电陶瓷，进一步完善低介LTCC材料性能调控的原理和方法，为类似微波介电材料的科学裁剪提供了实验与理论借鉴。此外，还对Bi3B5+xO12+3x/2(x=0~6)、Bi4B2+xO9+3x/2、Li2O-Al2O3-2B2O3、Li2O-2MgO-Al2O3-6MoO3等低温共烧LTCC材料体系以及Sr1+xSm2Al2O7+x、La2MgGeO6、Ln2MoO6(Ln=La、Y)、CaTiO3-LnAlO3(Ln=La, Nd)等高Q值微波介质陶瓷材料体系进行了相应的探索工作，并对材料的“组成—结构—性能”的关系进行了系统的研究。