BaTiO3 Dielectric Ceramic for Thin-Layer Capacitor Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dielectric ceramic layers in laminated ceramic capacitors face reliability and high-temperature load life characteristic degradation when reduced to less than 1 μm thickness, as they experience increased electric fields, necessitating improved grain boundary areas and crystal grain size reduction.
Innovation Solution
A dielectric ceramic composition with a main constituent of (Ba1-x/100)TiO3 and accessory constituents including Mg, Si, Mn, and rare earth elements, with an average grain size of 20 nm to 100 nm, is used to create highly insulating grain boundaries, enhancing reliability and high-temperature load life characteristics even at reduced thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric ceramic layer thickness is reduced to less than 1 μm to achieve reduction in size and increase in capacitance, then the capacitance and size requirements are met, but the reliability and high temperature load life characteristics are degraded due to increased electric field stress
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by incorporating specific amounts of MgO (0.1-5.0 mol%), SiO2 (0.1-5.0 mol%), MnO (0.1-5.0 mol%), and rare earth oxides (0.1-5.0 mol%) into the BaTiO3-based system. These compositional parameter changes modify the material properties to enhance grain boundary insulation, allowing the ceramic to maintain high reliability even when the layer thickness is reduced to less than 1 μm for high capacitance applications
Solution Approach 2:
The patent creates a composite dielectric ceramic material by combining BaTiO3-based main constituent with multiple accessory constituents including MgO, SiO2, MnO, and rare earth oxides. This composite structure forms a complex ceramic system where the combination of different materials works synergistically to provide both the required capacitance at thin layers and the necessary reliability through improved grain boundary characteristics
2Length of stationary object
If the dielectric ceramic layer thickness is reduced to less than 1 μm, then the layer thickness requirement is met, but the electric field applied per layer is relatively increased causing reliability degradation
Solution Approach 1:
The patent modifies the material parameters by adjusting the chemical composition to include specific ranges of MgO, SiO2, MnO, and rare earth oxides. These parameter changes result in altered electrical properties of the ceramic, specifically enhanced grain boundary insulation that enables the material to withstand higher electric fields at reduced thicknesses without compromising reliability
Solution Approach 2:
The patent applies local quality improvement by specifically targeting the grain boundary regions through the addition of MgO, SiO2, MnO, and rare earth oxides. These additives preferentially affect the grain boundary areas, creating locally enhanced insulation properties at the grain boundaries while maintaining the overall thin layer structure, thus improving reliability under increased electric field conditions
3Reliability
If the grain size of crystal grains is reduced to increase the grain boundary area, then the reliability is improved, but the manufacturing precision and control become more difficult
Solution Approach 1:
The patent uses compositional parameter changes as a control mechanism to influence grain growth during sintering. By adjusting the amounts of MgO, SiO2, MnO, and rare earth oxides, the material's sintering behavior is modified to naturally produce fine grains in the 1-10 μm range. This compositional control provides a more reliable and easier-to-manage method than direct mechanical or physical grain size control
Solution Approach 2:
The patent introduces MgO, SiO2, MnO, and rare earth oxides as intermediary substances that mediate the grain growth process during sintering. These intermediary materials affect the sintering kinetics and grain boundary mobility, indirectly controlling the final grain size to achieve fine grains without requiring direct or complex grain size control mechanisms, thus improving manufacturing precision
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 dielectric ceramic composition significantly improves the life characteristics of laminated ceramic capacitors, particularly at electric field strengths of 6.3 kV/mm and 12.6 kV/mm, by maintaining high reliability and extending the high-temperature load life, even when the dielectric ceramic layer thickness is less than 1 μm.
Implementation Method 1
it is effective to increase the grain boundary area by increasing the number of crystal grain boundaries in the dielectric ceramic. In order to increase the grain boundary area, it is necessary to reduce the grain size of the crystal grains
Implementation Method 2
a dielectric ceramic composition manufactured in accordance with a manufacturing method including a step of firing a main constituent raw material and an accessory constituent raw material
Data Source
AI summary
A laminated ceramic capacitor which provides favorable life characteristics, even when a high electric field strength is applied while dielectric ceramic layers are reduced in layer thickness to less than 1 μm, contains a dielectric ceramic a compound represented by: (Ba1-x/100Cax/100)mTiO3 (0≦̸x≦̸20) as its main constituent, and as its accessory constituent, aMg-bSi-cMn-dR (R is at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, and a, b, c, and d (part by mol) respectively satisfy the conditions of 0.1<a≦̸20.0, 0.5<b≦̸20.0, 0.1<c≦̸10.0, and 1.0<d≦̸30.0 with respect to 100 parts by mol of the main constituent). The average grain size is 20 nm or more and less than 100 nm for crystal grains in a sintered body obtained by firing the dielectric ceramic.