Dielectric characters of 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 ceramics fabricated at ultra-low temperature by the spark-plasma-sintering method

Solid solution (1 − x)Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ shows high dielectric constant near room temperature and is an ideal capacitor material. The composition 0.7Pb(Mg_1/3Nb_2/3)O₃–0.3PbTiO₃, which is located near the morphotropic phase boundary, were densified by the spark-plasma-sintering method at an ultra-low temperature (700 °C). Dielectric constant measurement shows that the thus prepared sample shows higher dielectric constant at room temperature and good temperature stability in a wide temperature range. The behavior is much different from that of samples sintered by conventional method and could be ascribed to size effect.     

Ni/Cu电极MLCC烧端工艺的研究

通过对烧端工艺的详细研究,给出了最佳工艺参数:烧端温度为850～880℃,保温10min;用N2/O2混合气,在排胶段保持φ(O2)为300×10–6,在高温烧结段采用φ(O2)为10×10–6;600℃以下的升温速率控制在30～40℃/min,600℃以上的升温速率控制在50～60℃/min。在上述工艺条件下,选用合适的链式连续炉,可以得到端头性能良好的MLCC产品。     

采用水基黏合剂制作MLCC工艺的研究

采用水基PVA黏合剂为主要原材料,研究了水基PVA黏合剂在瓷浆制备、流延、生坯层压等关键工艺,制作出MLCC,并与溶剂型PVB黏合剂MLCC比较.结果表明:采用水基PVA黏合剂能够制作出性能良好的MLCC.     

不同体系低温无铅玻璃在铜端电极浆料中的应用

研究了4种不同体系低温无铅玻璃粉在多层陶瓷电容(MLCC)铜端电极浆料中的应用。通过DSC、SEM等测试玻璃的玻璃化转变温度、析晶温度、烧结特性、耐酸性,并研究了玻璃粉对MLCC力学性能、电性能的影响。4种低温无铅玻璃的玻璃化转变温度不同,适合的烧结温度也有不同。在合适的烧结温度下,4种低温无铅玻璃均可以提供良好耐酸性、致密的端电极表面及合格的端电极附着力和MLCC电性能。2#(B-Zn-Na-Cu)玻璃的综合性能最优,满足MLCC对端电极浆料无铅低温高可靠性的要求。     

Multi-phase coexistence and temperature-stable dielectric properties in BaTiO3/ZnO composite ceramics

BaTiO₃:100xZnO composite ceramics with different ZnO particle sizes were prepared by using a conventional solid-state method. Phase constitution, microstructure and dielectric properties of BaTiO₃:100xZnO composite ceramics are investigated. Compared to micrometer scaled ZnO particles, nanometer scaled ZnO particles tend to agglomerate at lower ZnO contents in the BaTiO₃:100xZnO composite ceramics. The introduction of ZnO in BaTiO₃ leads to the reduction of grain size, decrease of the tetragonality and shift of phase transition temperature. The optimum composition is BaTiO₃ with 20 wt. % nanometer scaled ZnO particles, which has stable permittivity and low dielectric loss from -100 to 160 °C. The stable dielectric properties are proposed to be beneficiated from the stress induced multi-phase coexistence.     

Effect of TiO2 doped Ni electrodes on the dielectric properties and microstructures of (Ba0.96Ca0.04)(Ti0.85Zr0.15)O3 multilayer ceramic capacitors

The effects of TiO₂-doped Ni electrodes on the microstructures and dielectric properties of (Ba_0.96Ca_0.04)(Ti_0.85Zr_0.15)O₃ multilayer ceramic capacitors (MLCCs) have been investigated. Nickel paste with a TiO₂ dopant was used as internal electrodes in MLCCs based on (Ba_0.96Ca_0.04)(Ti_0.85Zr_0.15)O₃ (BCTZ) ceramic with copper end-termination. The microstructures and defects were analysed by microstructural techniques (SEM/HRTEM) and energy-dispersive spectroscopy (EDS). The continuity of the electrode of the MLCC was measured using a scanning electron microscope, which showed that the continuity of the electrode for the MLCC with a TiO₂-doped Ni electrode was approximately 90%. However, continuity of the electrode for a conventional MLCC was below 80%. The continuity of the TiO₂-doped Ni electrode showed significant improvement in the MLCC, which was due to no reaction between Ni and BCTZ.     

锆钛酸锶钙陶瓷材料主晶相组份与介电性能

采用固相法制备了CaxSr（1-x）〔Ti（1-y）Zry〕zO3（CSTZ锆钛酸锶钙）陶瓷,研究CSTZ系统陶瓷材料的组成与介电性能的关系。结果表明：当x为0.45,y为0.88,z为1.05时,主晶相CaxSr（1-x）〔Ti（1-y）Zry〕zO3形成完全互溶钙钛矿型固溶体。可获得具有理想介电性能、不含Pb和Cd等有害杂质的抗还原高频MLCC瓷料。     

MLCC在DC/DC变换器中的应用和优化设计

通过分析电容器的寄生效应和频率特性,研究电容器等效串联电阻对DC/DC变换器电性能和稳定性的影响;明确了多层陶瓷电容器(MLCC)在DC/DC变换器应用中与其他种类电容器的不同之处;并对多层陶瓷电容器的优化设计方法进行探讨,用具体电路说明了优化设计过程。     

Solution-based aerosol deposition process for synthesis of multilayer structures

In this paper, we report the progress on 3D aerosol deposition of barium titanate (BTO) based multilayer ceramic capacitors (MLCC) using an automated process. Solution-based aerosol deposition is a promising direct-write method to produce three-dimensional (3D) structures at low temperatures. We utilize the combination of solution-based aerosol process and selective laser sintering (SLS) to develop 3D structures. The MLCC structure was synthesized on silicon substrate consisting of alternate layers of 0.5-1.0 μm thick silver electrode layer and 0.5-2 μm thick BTO ceramic. The effect of incident laser power subsequent to deposition (in the range of 105 mW and 930 mW) was systematically investigated revealing the changes in grain morphology as a function of local sintering. The results of this study are promising for development of on-substrate thin/thick film MLCCs.     

MLCC在平板电源中的断裂原因分析与改进措施

为了解决平板电源制备过程中所用片式多层陶瓷电容器(MLCC)的开裂问题,通过DPA(Destructive Physical Analysis)方法分析了MLCC在平板电源中的开裂模式。结果表明,主要开裂模式为弯曲开裂。通过将MLCC的材质由X7R调整为NPO,尺寸由1206改为0805,同时增加PCB板厚度并规范SMT安装方式,调整焊接工艺以及使用规范的成品检验方式等措施,可解决或者改善平板电源用MLCC的断裂现象,提高产品的可靠性。