Preparation And Microwave Dielectric Properties Of Zinc Borate Ceramics With Low Sintering Temperature

With the rapid development of electronic technology, the miniaturization of packaging,assembly of high density and the generation of new packaging technologies, therequirements of quality of electronic assembly are also increasing. In the information age,LTCC technology can provide a better solution for the smaller and lighter of variety ofelectronic systems. The substrate technology of LTCC is used as the substrate for the fifthgeneration of electronic assembly. It became the mainstream technology of the passivetechnology. So, it is interests and important in researching the LTCC.In the paper, the preparation, cast, microwave dielectric properties and the co-firingwith Ag of zinc borate ceramics were investigated. The materials were prepared by theconventional solid state ceramic oxide route and sintered into ceramics. The researchstudied about the effects of the content of ZnO, the sintering temperature and the soakingtime on the microwave dielectric properties, sintering characteristics, crystal phase of thezinc borate ceramic system at first. The composition and microstructure of the zinc borateceramics were investigated by X-ray diffraction （XRD） and scanning electron microscopy（SEM） respectively. The microwave dielectric properties of the ceramic samples weremeasured by the network analyzer. The research showed that the zinc borate ceramicsystem has chemical compatibility of Ag. When the content of ZnO up to the71.429mol%,it can obtain good sintering characteristics and microwave dielectric properties. Theseceramics sintered at950°C for3h showed the microwave dielectric properties of: ε_r⁶.9,Q×f²0000GHz （@6.32GHz）.Meanwhile, the dense zinc borate ceramics with thiscomposition were obtained in the temperature range from950to1000°C for3h.The X-raydiffraction showed that the obtained ceramics were of a monoclinic3ZnO·B₂O₃structure.Therefore, we called the zinc borate ceramic with this composition as3ZnO·B₂O₃ceramic.The3ZnO·B₂O₃ceramic specimens fired at955°C for1h exhibited excellent microwavedielectric properties: ε_r⁶.9, Q×f²0647GHz （@6.35GHz） and τf^-80ppm/°C. Thedependences of relative density, ε_r, and Q×f of ceramics sintered at955°C on sinteringsoaking time showed that they all reached their plateaus as the soaking time was up to1h.During the casting, we selected the3ZnO·B₂O₃ceramic as the powder of the casting. The casting was realized by modifying the ratio of ceramic and organic solvent. Aftercasting, we studied sintering characteristics and co-firing with Ag of the green tape.Meanwhile,3ZnO·B₂O₃ceramics had no reaction with silver during cofiring, indicating it isa potential candidate for low-temperature cofired ceramic （LTCC） substrate. During thecasting, when the mass percent of the3ZnO·B₂O₃ceramic powder was up to the52.625%,it can attain green tape with good sintering properties.