Preparation And Properties Of CaO-SiO₂-B₂O₃ Dielectric Ceramics For LTCC Appliactions

With the advent of the electronic information age,the development of electronic components technology has been promoted.Electronic devices need to be developed in the direction of small size,high frequency,high stability and high integration.Therefore,the performance of electronic packaging technology has higher requirements,which made the development and fabrication of low temperature co-fired ceramics(LTCC)substrate material and process become today's research hotspots.CaO-B2O3-SiO2(CBS)dielectric ceramics are one kind of LTCC,which contain wollastonite(Ca3[Si3O9])as the main crystalline phase.The wollastonite has low dielectric constant and dielectric loss.At the same time,it has excellent thermal and mechanical properties,which makes this kind of LTCC widely used in packaging substrate materials and dielectric materials.However,Ca-B-Si ceramics have some shortcomings,such as not compact enough after sintering and exorbitant sintering temperature,which need further study.In this study,the sintering degree and electrical properties of CBS ceramics with different formulations and sintering temperatures were thoroughly investigated.The influence of different content of LiF additives on the samples' compactness was studied through the composition,microstructure and properties of the ceramics.Finally,the dielectric properties of CBS ceramics composited by high-performance ceramics MgTiO3 were studied.The effects of electrical properties and mechanical properties of ceramics and doping additives on the compactness of MgTiO3/CBS composite ceramics were thoroughly explored.The experimental results show that the optimum sintering temperature of pure CBS ceramics was 950 0C The main crystalline phase is ?-CaSiO3 with a small amount of SiO2 crystal and residual B2O3 glass,and meanwhile the density and properties decreased at first and then increase.Moreover,excessive B2O3 was not conducive to the product of the main crystalline phase ?-CaSiO3.Adding appropriate amount of LiF played a great role in reducing the sintering temperature of CBS ceramics,which broke the technical barrier of solid-state reaction for LTCC application,and improved the densification of ceramics by reducing the glass viscosity in the sintering process.MgTiO3/CBS ceramic composites with low dielecttic loss were prepared in a certain proportion of CBS and MgTiO3.Finally,nano-A12O3 was used to improve the mechanical perfromance of the composite system,Compared with other experimental samples and commercial products,sample A4 sintered at 850? for 60 min displayed the microstructure of less porosity and showed superior dielectric performance and mechanical properties,including bulk density of 3.1482 g/cm3,?r of 11.47,tan? of 2.4×10-4 and pv of 12.80×1011 ?·cm at 1MHz,flexural strength of 269.23 MPa and thermal conductivity of 3.246 W/(m·K).