Dielectric Ceramic Composition for High-Permittivity MLCCs
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Solution Overview
Problem
Existing dielectric ceramic compositions face challenges in achieving high permittivity and reliability, particularly due to difficulties in controlling reaction and sintering properties with varying rare earth atoms and thin dielectric layers, which affect withstand voltage and high-temperature insulation resistance.
Innovation Solution
A dielectric ceramic composition with solid-solubilized rare earth atoms in a base material, along with specific sub-components like Mg, Si, and metal oxides, is used to enhance permittivity and reliability, with a focus on controlling the m and x values to optimize firing temperature and grain size, and incorporating aluminum oxide to widen the firing window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric layer is made thinner to achieve miniaturization and high capacitance, then the capacitance density increases, but the withstand voltage characteristics and high-temperature insulation resistance deteriorate due to increased electric field intensity and structural defects
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric material by incorporating specific rare earth elements (lanthanum, cerium, praseodymium, neodymium, or samarium) at controlled concentrations (0.1-5 wt%) into the barium titanate base material. This composition modification enables the thin dielectric layer to maintain high breakdown voltage and insulation resistance while achieving high capacitance density, thus resolving the contradiction between miniaturization and reliability.
Solution Approach 2:
The patent creates a composite dielectric material system by combining barium titanate (BaTiO3) with rare earth oxides and sintering aids (such as Nb2O5, Ta2O5, WO3, MoO3). This composite structure provides both the high permittivity needed for high capacitance density and the enhanced electrical stability required for good withstand voltage characteristics in thin films.
2Reliability
If the grain size of the base material is decreased to achieve atomization and prevent structural defects, then the withstand voltage characteristics improve, but it becomes more difficult to implement capacitance temperature characteristics and permittivity may decrease
Solution Approach 1:
The patent optimizes the grain size parameter to a specific range (0.5-2.0 μm) through controlled sintering processes and composition adjustments. This intermediate grain size achieves a balance: it is fine enough to reduce structural defects and improve withstand voltage, yet large enough to maintain stable capacitance temperature characteristics and high permittivity. The rare earth additions facilitate achieving this optimal grain size control.
Solution Approach 2:
The patent introduces rare earth elements that locally modify the grain boundary properties and crystal structure of the barium titanate. This local modification enables the material to exhibit improved electrical properties at grain boundaries while maintaining appropriate grain growth, thus simultaneously achieving good withstand voltage characteristics and stable capacitance temperature characteristics.
3Quantity of substance
If rare earth atoms are added to BaTiO3 to enhance dielectric properties, then permittivity improves, but it becomes difficult to control reaction and sintering properties when changing the kind of rare earth atoms
Solution Approach 1:
The patent identifies a universal set of sintering aid oxides (Nb2O5, Ta2O5, WO3, MoO3) that work effectively with all the selected rare earth elements (lanthanum, cerium, praseodymium, neodymium, samarium). This universal sintering aid system provides consistent reaction control and sintering behavior across different rare earth compositions, enabling standardized manufacturing processes while maintaining high permittivity.
Solution Approach 2:
The patent uses sintering aid oxides as intermediary substances that mediate between the rare earth atoms and the barium titanate matrix. These intermediaries control the reaction kinetics and sintering behavior, ensuring consistent processing characteristics regardless of which rare earth element is used, thus facilitating ease of manufacture while achieving high permittivity.
4Volume of moving object
If the dielectric layer is made thinner to reduce chip size, then miniaturization is achieved, but oxygen vacancy movement becomes difficult to control causing deterioration of reliability
Solution Approach 1:
The patent modifies the chemical composition by adding rare earth elements and sintering aids that alter the oxygen vacancy formation energy and migration barriers. This composition parameter change enables effective oxygen vacancy control even in thin dielectric layers, preventing reliability deterioration while achieving miniaturization. The rare earth dopants specifically address oxygen vacancy issues through their electronic structure and bonding characteristics.
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 achieves high permittivity and reliable dielectric properties, ensuring stable capacitance and high-temperature performance, as demonstrated by the dielectric constant of 1800 and excellent high-temperature accelerated life characteristics in multi-layer ceramic capacitors.
Implementation Method 1
A dielectric ceramic composition with solid-solubilized rare earth atoms in a base material
Implementation Method 2
controlling the m and x values to optimize firing temperature and grain size
Data Source
AI summary
A dielectric ceramic composition including a base material represented by (Ba(1-x)+REx)mTiO(3+x) (here, 0.995≦̸m≦̸1.010, 0.001<x<0.010, and RE is at least one rare earth (RE) atom selected from a group consisting of Dy, Y, Ho, Sm, and Gd) or Bam(Ti+REx)O(3-x) (here, 0.995≦̸m≦̸1.010, 0.001<x<0.010, and RE is at least one RE atom selected from a group consisting of Dy, Y, Ho, Sm, and Gd) as a main component, and a multi-layer ceramic capacitor using the same. In the dielectric ceramic composition, high permittivity (dielectric constant of 1800 or more) and high temperature reliability may be secured by using a RE atom doped/solid-solubilized base material and adding oxides, which are sub-components.