Dielectric Ceramic for Monolithic Capacitors
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Solution Overview
Problem
Dielectric ceramic materials used in thin-layer monolithic ceramic capacitors experience significant capacitance fluctuations and deteriorated AC voltage characteristics due to high field strength, leading to reliability issues and reduced high-temperature load life.
Innovation Solution
A dielectric ceramic composition with calcium-free barium titanate as the primary component, incorporating specific rare earth and metal additives, with solid solution regions of secondary components limited to 10% or less, ensuring stable capacitance and improved temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer is made thinner to miniaturize the monolithic ceramic capacitor, then the capacitance density is improved, but the dielectric constant is reduced and temperature characteristic deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by using a specific multi-component system (BaTiO3-SrTiO3-Pb(Zr,Ti)O3 with rare earth elements and SiO2) to achieve both thin layer compatibility and stable temperature characteristics. This compositional parameter adjustment allows the dielectric to maintain high dielectric constant and good temperature stability even at reduced thickness.
Solution Approach 2:
The patent employs a composite dielectric material system combining multiple ceramic phases (BaTiO3, SrTiO3, Pb(Zr,Ti)O3) with rare earth element additives and SiO2. This composite structure provides synergistic effects that enable the thin dielectric layer to simultaneously achieve high capacitance density and reliable temperature characteristics.
2Volume of moving object
If the dielectric layer is made thinner to increase capacitance density, then the miniaturization is achieved, but the high-temperature load life is reduced
Solution Approach 1:
The patent adjusts the chemical composition parameters by incorporating rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) and SiO2 into the BaTiO3-based dielectric system. These compositional changes enhance the material's thermal stability and resistance to high-temperature degradation, thereby extending load life in thin-layer structures.
Solution Approach 2:
The patent uses SiO2 as a sintering aid and stabilizing component that forms a protective glassy phase during sintering. This phase acts as a barrier against thermal degradation and extends the service life of the thin dielectric layer under high-temperature operating conditions.
3Volume of moving object
If conventional dielectric materials are used in thin layers, then miniaturization is achieved, but capacitance fluctuation increases under AC voltage
Solution Approach 1:
The patent optimizes the compositional parameters of the dielectric ceramic by precisely controlling the ratios of BaTiO3, SrTiO3, Pb(Zr,Ti)O3, rare earth elements, and SiO2. This parameter optimization ensures that the dielectric maintains stable capacitance under AC voltage conditions even when fabricated as thin layers, by reducing compositional inhomogeneity and enhancing electrical stability.
Solution Approach 2:
The patent uses a composite dielectric system where rare earth elements and SiO2 form a stable matrix that suppresses capacitance fluctuation under AC voltage. The multi-phase composite structure provides electrical stability and reduces the impact of high field strength effects that cause capacitance variation in conventional materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a dielectric ceramic with a stable AC voltage characteristic, maintaining a large dielectric constant and low dielectric loss, ensuring reliability and high-temperature load life, with capacitance changes within ±10% across varying voltages and temperatures.
Implementation Method 1
A dielectric ceramic having a good AC voltage characteristic, which maintains a desired large dielectric constant and a good temperature characteristic, exhibits a small dielectric loss
Data Source
AI summary
A dielectric ceramic represented by a general formula: 100BamTiO3+aROn+bMOv+cXOw (where R represents a rare earth element, M represents a predetermined metal element, and n, v, and w represent independently a positive number determined in accordance with the valences of the elements R and M and a sintering aid component X, respectively), and the solid solution regions of the secondary components in the main phase grains are 10% or less (including 0%) on average in terms of a cross-sectional area ratio. The sintering aid component X contains at least Si, and m, a, b, and c satisfy 0.995≦m≦1.030, 0.1≦a≦2.0, 0.1≦b≦3.0, and 0.1≦c≦5.0. In a monolithic ceramic capacitor, dielectric layers are formed from the above-described dielectric ceramic. Consequently, a dielectric ceramic having a good AC voltage characteristic, maintaining a desired large dielectric constant and a good temperature characteristic, exhibiting a small dielectric loss, and being capable of ensuring the reliability and a monolithic ceramic capacitor including the dielectric ceramic are realized.