Dielectric Ceramic Composition for Laminated Capacitors
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Solution Overview
Problem
Laminated ceramic capacitors face challenges in reducing size while maintaining high capacitance and reliability, particularly when subjected to high electric fields, due to variations in grain diameter and shortened high-temperature load life.
Innovation Solution
A dielectric ceramic composition of 100(Ba1-xCax)TiO3+aMgO+bVO5/2, with specific ranges for x, a, and b, is used to reduce grain diameter variations, enhancing high-temperature load life and capacitance characteristics, and a laminated ceramic capacitor design with stacked dielectric layers and internal electrodes is implemented.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the dielectric ceramic layer is reduced to 1 μm or less to reduce the size of the laminated ceramic capacitor, then the capacitance per unit volume increases, but the strength of the electric field applied to the dielectric ceramic layer increases, leading to shortened high temperature load life and larger variations in life
Solution Approach 1:
The invention changes the chemical composition parameters of the dielectric ceramic by adding specific amounts of MnO (0.1-5.0 wt%) and SiO2 (0.1-5.0 wt%) to the (Ba1-xCax)TiO3 base composition. This parameter change modifies the grain growth characteristics and dielectric properties, enabling the ceramic to maintain high reliability under high electric field conditions even when the layer thickness is reduced to 1 μm or less.
Solution Approach 2:
The invention creates a composite dielectric ceramic material by combining (Ba1-xCax)TiO3 with MnO and SiO2 additives. This composite structure provides both the high dielectric constant needed for high capacitance and the grain boundary control needed for high reliability under high electric fields, resolving the contradiction between size reduction and reliability maintenance.
2Reliability
If various elements such as V are added to the dielectric ceramic to improve reliability, then the high temperature load life improves, but large variations in grain diameter occur, leading to shortened high temperature load life and larger variations in life when high electric field is applied
Solution Approach 1:
The invention changes the compositional parameters by adding MnO and SiO2 in specific weight ratios (0.1-5.0 wt% each) to the dielectric ceramic. This controlled parameter change achieves grain refinement and uniformity, reducing grain diameter variations while improving high temperature load life, unlike the addition of V which causes large grain diameter variations.
Solution Approach 2:
The invention applies local quality control at the grain boundary level by adding MnO and SiO2, which preferentially segregate to grain boundaries. This creates a modified grain boundary structure that controls grain growth locally, resulting in uniform grain sizes throughout the ceramic while maintaining high reliability under high electric field conditions.
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 favorable high-temperature load life characteristics, reduced grain diameter variations, and improved capacitance, achieving a high dielectric constant and specific resistance under high electric fields, while maintaining reliability even at reduced thickness.
Implementation Method 1
dielectric ceramic layers provided in laminated ceramic capacitors... high dielectric constant... favorable capacitance temperature characteristics
Implementation Method 2
BaTiO3 based compounds have been used as main constituents of the dielectric ceramics... high reliability (high temperature load life characteristics) and favorable capacitance temperature characteristics
Data Source
AI summary
A laminated ceramic capacitor which has a long high temperature load life, small variations in life, large capacitance, high electrical insulation property, and favorable capacitance temperature characteristics, even when high strength electric field is applied while reducing the thickness of dielectric ceramic layers uses a dielectric ceramic represented by the formula: 100(Ba1-xCax)mTiO3+aMgO+bVO5/2+cReO3/2+dMnO+eSiO2 where Re being at least one of Y, La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), 0.05≦x≦0.15, 0.01≦a≦0.1, 0.05≦b≦0.5, 1.0≦c≦5.0, 0.1≦d≦1.0, 0.5≦e≦2.5, and 0.990≦m≦1.030.