BaTiO3 Dielectric Ceramic for Laminated Capacitor AC Voltage Stability
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Solution Overview
Problem
Laminated ceramic capacitors with thin dielectric layers experience significant variations in capacitance due to changes in applied electric field, leading to deteriorated AC voltage characteristics, reliability issues, and reduced temperature stability.
Innovation Solution
A dielectric ceramic composition with a perovskite-type compound (ABO3) containing Ba, Ca, Sr, Ti, Zr, Hf, and rare earth elements, where Ni is uniformly solid-solved in crystal grains, and the rare earth element is limited to an average solid-solution region of 10% or less, along with specific molar ratios of NiO, RO, MO, MgO, and SiO, to enhance AC voltage characteristics and maintain dielectric and temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer is thinned to achieve downsizing, then the capacitance can be maintained, but the dielectric constant decreases and reliability deteriorates due to high field voltage intensity
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by adding specific amounts of NiO (0.01-5 mol%) and rare earth element oxides (0.01-5 mol%) to the BaTiO3-based system. This compositional modification enables the dielectric layer to maintain high dielectric constant and reliability even when thinned, thereby resolving the contradiction between downsizing and reliability.
Solution Approach 2:
The patent creates a composite dielectric material system combining BaTiO3-based perovskite with NiO and rare earth element oxides (such as La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, or Y2O3). This composite approach enhances the material's intrinsic properties to withstand high field voltage intensity in thinned structures.
2Volume of moving object
If the dielectric layer is thinned, then downsizing is achieved, but AC voltage characteristics deteriorate due to large capacitance variation with applied electric field
Solution Approach 1:
The patent modifies the dielectric material's electrical parameters through controlled addition of NiO and rare earth oxides, which stabilizes the capacitance against applied electric field variations. This enables thinned dielectric layers to maintain excellent AC voltage characteristics with capacitance variation within ±8%.
3Volume of moving object
If conventional dielectric ceramic is used in thinned structure, then downsizing is achieved, but temperature characteristics deteriorate
Solution Approach 1:
The patent develops a composite dielectric system incorporating rare earth element oxides into the BaTiO3-NiO base composition. The rare earth elements (such as La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y) stabilize the perovskite structure and improve temperature characteristics, enabling the thinned capacitor to maintain capacitance variation within ±22% across -55°C to +105°C.
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 results in a laminated ceramic capacitor with improved AC voltage characteristics, maintaining a high dielectric constant, reduced dielectric loss, and excellent reliability, with capacitance variation within ±8% and temperature stability across −55° C to +105° C, while ensuring a high insulation breakage voltage and long-term reliability.
Implementation Method 1
the Ni is uniformly or substantially uniformly solid-solved in the crystal grains, and the average solid-solution region of the rare earth element R in the crystal grains is 10% or less (including 0%) in terms of the cross section ratio
Data Source
AI summary
A dielectric ceramic contains a BaTiO3-based compound as a main ingredient, and can be represented by the general formula: 100AmBO3+aNiO+bROn+cMOv+dMgO+eXOw where R represents a rare earth element such as Dy, M represents a metal element such as Mn, and X represents a sintering aid component containing Si. Ni is uniformly solid-solved in crystal grains, and the solid-solution region of the rare earth element in the crystal grains is an average 10% or less in terms of a cross section ratio. 0.96≦m≦1.030, 0.05≦a≦3, 0.1≦b≦1.5, 0.1≦c≦1.0, 0.1≦d≦1.5, and 0.05≦e≦3.5 are satisfied. A laminated ceramic capacitor has dielectric layers formed of the dielectric ceramic. As a result, a dielectric ceramic, and a laminated ceramic capacitor having excellent AC voltage characteristics, capable of keeping desired dielectric characteristics and excellent temperature characteristics, and having excellent withstand voltage and capable of ensuring reliability can be realized.