Multilayer Capacitor Dielectric Structure for IR Degradation Control
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in maintaining reliability and dielectric constant under severe conditions due to grain size reduction and atomization, leading to IR degradation and capacitance decrease.
Innovation Solution
The introduction of a multicore-shell structure in dielectric grains, where multiple cores are surrounded by a shell, increases the specific resistance and maintains grain size, thereby preventing IR degradation and compensating for dielectric constant decreases even when grains are atomized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the grain size of barium titanate is reduced to increase withstand voltage, then the voltage applied per grain increases, but the dielectric constant decreases and IR degradation occurs
Solution Approach 1:
The dielectric grain is segmented into a core-shell structure where the core contains fine barium titanate grains (providing high withstand voltage) and the shell contains coarse grains (providing high dielectric constant). This segmentation allows simultaneous optimization of both withstand voltage and dielectric constant without IR degradation.
2Strength
If the grain size of barium titanate is reduced to increase withstand voltage, then the voltage applied per grain increases, but the dielectric constant decreases
Solution Approach 1:
Different regions of the dielectric grain are assigned different qualities: the core region has fine grains optimized for high withstand voltage, while the shell region has coarse grains optimized for high dielectric constant. This local quality differentiation resolves the contradiction between withstand voltage and dielectric constant.
3Reliability
If rare earth elements are increased as additives to the dielectric material, then reliability is improved, but the complexity of material composition increases
Solution Approach 1:
The patent optimizes the concentration parameters of rare earth elements (Nd, Sm, Eu) within specific ranges (0.01-0.1 mol% each) to achieve high reliability. By controlling the quantitative parameters rather than qualitatively changing the material system, reliability is improved without excessive complexity.
Data Source
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AI summary
A multilayered capacitor including a capacitor body including a dielectric layer and internal electrodes, and an external electrode outside the capacitor body, wherein the dielectric layer includes a plurality of dielectric grains, at least one of the plurality of dielectric grains has a multicore-shell structure, and the dielectric grains having the multicore-shell structure include two or more dielectric cores and shells surrounding at least some of the cores.