Dielectric Ceramic Composition for MLCC Temperature Stability
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving a high dielectric constant, long insulation resistance life, and stable temperature characteristics across a broad temperature range, particularly in harsh automotive environments, with existing dielectric ceramic compositions falling short in meeting X7R and X8R standards.
Innovation Solution
A dielectric ceramic composition with barium titanate as the main ingredient and a diffusion phase that disperses sub-ingredients such as rare earth elements and magnesium, calcium, and manganese, where the average diffusion depth of these elements varies between 5 to 30% of the dielectric particle's average size, optimizing the dielectric constant, high temperature accelerated life, and insulation resistance temperature dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the dielectric ceramic composition uses a uniform diffusion phase thickness, then the manufacturing process is simple, but the dielectric constant and temperature characteristics cannot be optimized simultaneously
Solution Approach 1:
The patent applies local quality by creating a non-uniform diffusion phase thickness distribution where the thickness varies from the particle center to the surface. Specifically, the diffusion phase thickness is controlled to be 10-30 nm at the particle surface and 3-15 nm at the particle center, creating localized compositional differences that optimize both dielectric constant and temperature characteristics simultaneously
2Reliability
If the diffusion phase thickness is increased to improve insulation resistance life, then the high temperature accelerated life improves, but the dielectric constant decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the diffusion phase thickness within specific ranges (10-30 nm at surface, 3-15 nm at center) and adjusting the ratio of sub-ingredients (CaO: 0.1-3.0 mol, SiO2: 2-10 mol, rare earth oxides: 0.5-7.0 mol) to achieve the optimal balance between insulation resistance life and dielectric constant. This quantitative parameter optimization resolves the trade-off between these two properties
3Quantity of substance
If the diffusion phase thickness is decreased to improve dielectric constant, then the dielectric constant increases, but the high temperature accelerated life and insulation resistance temperature dependency worsen
Solution Approach 1:
The patent applies local quality by creating different diffusion phase thicknesses at different locations within the particle. The thicker diffusion phase at the surface (10-30 nm) provides protection against high temperature degradation and maintains insulation resistance, while the thinner diffusion phase at the center (3-15 nm) preserves the piezoelectric properties and dielectric constant of the main ingredient phase
Solution Approach 2:
The patent applies composite materials by creating a multi-phase structure consisting of the main ingredient phase (barium titanate-based piezoelectric material) and the diffusion phase (containing CaO, SiO2, and rare earth oxides). This composite structure combines the high dielectric constant of the main phase with the protective and stabilizing properties of the diffusion phase, achieving both high dielectric constant and improved high temperature reliability
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 composition achieves a balanced improvement in dielectric constant, high temperature accelerated life, and insulation resistance temperature dependency, effectively satisfying X7R and X8R characteristics by varying the diffusion depth of sub-ingredients, enhancing the capacitors' performance in extreme temperatures.
Implementation Method 1
a diffusion phase present at the periphery of the main ingredient phase, wherein when an average value of the depth where a sub ingredient element present at the diffusion phase diffuses from a surface of the diffusion phase toward a center of the dielectric particle is designated as an average diffusion depth
Data Source
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AI summary
A dielectric ceramic composition including dielectric particles comprising a main ingredient phase having barium titanate as its main ingredient and a diffusion phase present at the periphery of said main ingredient phase, wherein when an average value of the depth where sub ingredient elements present at said diffusion phase diffuses from a surface of said diffusion phase toward a center of said dielectric particle is designated as an average diffusion depth, a dispersion of the average diffusion depth among the dielectric particles is, in terms of CV value, 5 to 30%. According to the present invention, an electronic device excellent in all of the dielectric constant, high temperature accelerated life, TC bias, and IR temperature dependency can be provided. The CV value corresponding to an average diffusion depths in 30 particles. The element which diffuse into the dielectric particle being Yb, Mg and Ca.