MLCC Dielectric Particle Composition for High Capacitance Reliability
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in achieving a reduction in size and increase in capacitance while maintaining reliability due to the influence of fine defects in dielectric layers, leading to insulation resistance reduction and insulation breakdown.
Innovation Solution
The use of dielectric particles with a core-shell structure and controlled intra-particle concentration distribution, combined with a specific ratio of core-shell and uniform solid solution particles, enhances dielectric constant and insulation resistance, thereby improving reliability and enabling smaller, higher-capacitance capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric layer is thinned to reduce size and increase capacitance, then the electrostatic capacitance increases, but the insulation resistance decreases and reliability deteriorates due to increased electric field strength and fine defects
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the shell portion has a different composition (higher concentration of sub-components like rare earth elements) than the core portion. This localized compositional variation allows the shell to provide enhanced insulation resistance at the particle surface, compensating for the overall thinning of the dielectric layer and preventing insulation breakdown while maintaining high capacitance.
2Volume of moving object
If the dielectric layer is thinned to reduce size, then the device size decreases, but the strength of electric field per layer increases causing insulation breakdown
Solution Approach 1:
The patent employs composite materials by combining core and shell portions with different compositions within the same dielectric particle. The shell portion, enriched with sub-components such as rare earth elements, creates a composite structure that enhances the overall insulation strength of the particle, enabling the dielectric layer to withstand higher electric field strengths despite reduced thickness.
3Reliability
If core-shell particles with high sub-component concentration in shell are used to improve reliability, then insulation resistance increases, but the dielectric constant may be reduced
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration of sub-components in the shell portion and the ratio of core-shell particles to uniform solid solution particles. By optimizing these parameters, the invention achieves a balance where the shell provides sufficient insulation enhancement without excessively reducing the dielectric constant, maintaining both reliability and capacitance performance.
Data Source
AI summary
A multilayer ceramic capacitor includes an element body portion and a pair of outer electrodes on first and second end surfaces and connected to inner electrode layers. The element body portion includes first and second side margin portions, and first and second outer layer portions, and an inner layer portion. A dielectric includes dielectric particles including barium and titanium, and, as sub- components, rare earth elements, and one or more first additional elements. In a cross section crossing a center in a length direction, dielectric layers included in an inner layer portion include core-shell particles and uniform solid solution particles. A ratio of average areas occupied by the core-shell particles and the uniform solid solution particles is about 0.8 to about 1.5, and a coefficient of variation of a first additional element concentration in the uniform solid solution particles is equal to or less than about 20%.