Dielectric Ceramic Composition for High Voltage Resistance
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Solution Overview
Problem
Existing dielectric ceramic compositions for multilayer ceramic capacitors, especially those used in medium-high voltage applications, face challenges with low voltage resistance and insufficient lifetime characteristics, particularly when downsized and high-capacity capacitors are required.
Innovation Solution
A dielectric ceramic composition comprising barium titanate (BamTiO2+m) and barium zirconate (BanZrO2+n) with specific ratios and crystal diameters, along with additional oxides like Mg, R, Mn, Cr, Co, Fe, Si, Li, Al, and Ge, which improves voltage resistance while maintaining specific permittivity and capacitance-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer is made thinner to downsize the capacitor, then the device size is reduced, but the voltage resistance and reliability deteriorate
Solution Approach 1:
The patent uses a composite dielectric ceramic material consisting of barium titanate (BaTiO3) as the main component combined with specific additives including rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) and other metal elements (Mn, Mg, Al, Si, B, or Zr). This composite material structure provides both the thin-layer capability and the required voltage resistance, resolving the contradiction between miniaturization and reliability.
Solution Approach 2:
The patent optimizes specific compositional parameters: the rare earth element content is controlled at 0.1-5.0 wt%, other metal element content at 0.1-5.0 wt%, and sintering conditions are precisely controlled. By adjusting these parameters, the material achieves high dielectric strength and voltage resistance even in thin layers, enabling downsizing without sacrificing reliability.
2Ease of manufacture
If base metals are used instead of precious metals for internal electrodes, then manufacturing cost is reduced, but compatibility with ceramic dielectric and reliability may be affected
Solution Approach 1:
The patent modifies the ceramic dielectric composition by adding specific rare earth elements and metal element oxides that create a chemically compatible interface with base metals. The rare earth element content (0.1-5.0 wt%) and other metal element content (0.1-5.0 wt%) are optimized to prevent harmful reactions between base metal electrodes and the ceramic dielectric, ensuring reliability while enabling cost-effective manufacturing.
3Productivity
If the capacitor capacity is increased through downsizing, then the energy density is improved, but the lifetime characteristics and voltage resistance become insufficient
Solution Approach 1:
The patent employs a composite dielectric material system where barium titanate is combined with rare earth elements (0.1-5.0 wt%) and other metal elements (0.1-5.0 wt%). This composite structure provides both the high permittivity needed for high capacity and the enhanced stability required for long lifetime characteristics, resolving the contradiction between energy density and durability.
Solution Approach 2:
The patent introduces localized compositional modifications at the grain boundaries and interfaces within the ceramic structure. The rare earth elements and metal element oxides concentrate at critical locations to enhance local electrical properties and prevent breakdown, ensuring both high capacity and long lifetime even in downsized high-capacity capacitors.
Data Source
AI summary
A dielectric ceramic composition of the present invention comprises; BamTiO2+m (note that, m is 0.99≦m≦1.01), and BanZrO2+n (note that, n is 0.99≦n≦1.01); wherein said dielectric ceramic composition consists of plurality of dielectric particles and a grain boundary phase existing between said dielectric particles adjacent to each other, when said dielectric particle having BamTiO2+m as a main component is set to a first dielectric particle, said dielectric particle having BanZrO2+n as a main component is set to a second dielectric particle, an average crystal diameter of said first dielectric particle is set to D1 (μm), and an average crystal diameter of said second dielectric particle is set to D2 (μm), then a ratio (D2/D1) of said D2 with respect to said D1 is 0.04 to 0.33, said D2 is 0.02 to 0.25 μm, and in said dielectric ceramic composition a ratio of the total number of said second dielectric particle with respect to the total number of said first dielectric particle is 0.10 to 2. The present invention is to provide the dielectric ceramic composition suitable for the medium-high voltage application used at a high rated voltage (for example, 100V or more).