Multilayer Ceramic Capacitor Cover Layers with Graded Dielectric Grain Sizes
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues due to mismatched sintering contraction ratios between the capacitance and cover portions, leading to potential cracks and reduced reliability when dielectric layers are thinned and the number of stacked layers is increased.
Innovation Solution
The electronic component features alternately stacked cover layers with different average diameters of dielectric grains, resulting in varying sintering temperatures that align the sintering contraction of the capacitance and cover portions, reducing the likelihood of cracks and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dielectric layers are thinned and the number of stacked layers is increased to achieve high capacitance, then capacitance is improved, but reliability deteriorates due to mismatched sintering contraction ratios between capacitance and cover portions causing cracks
Solution Approach 1:
The patent applies local quality by creating cover layers with different dielectric grain sizes (first cover layers with larger grains, second cover layers with smaller grains) to produce different sintering contraction ratios in different regions. This local variation in material properties allows the cover portion to match the sintering contraction of the capacitance portion, preventing cracks while maintaining the thin-layer, high-stack configuration needed for high capacitance.
2Volume of moving object
If the body is thinned to reduce component size, then device size is reduced, but reliability deteriorates due to increased susceptibility to cracks from sintering contraction mismatch
Solution Approach 1:
By implementing cover layers with differentiated dielectric grain sizes, the patent creates localized zones with different sintering contraction characteristics. This allows the thinned body structure to be compensated for by the tailored cover portion, which can accommodate dimensional changes during sintering without generating cracks, thereby maintaining reliability in miniaturized components.
3Reliability
If alternately stacked cover layers with different dielectric grain sizes are implemented, then reliability is improved by matching sintering contraction ratios, but device complexity increases
Solution Approach 1:
The patent segments the cover portion into multiple cover layers with different dielectric grain sizes, stacked alternately. This segmentation allows each layer to contribute differently to the overall sintering contraction, creating a gradient effect that matches the capacitance portion's contraction ratio. While this increases structural complexity, it provides a systematic approach to controlling dimensional stability during sintering.
Solution Approach 2:
The cover portion functions as a composite structure combining materials with different dielectric grain sizes in an alternating pattern. This composite approach enables the cover portion to exhibit averaged or gradient sintering contraction characteristics that can be tuned to match the capacitance portion, improving reliability through material composition rather than simple geometric scaling.
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
This configuration allows for excellent reliability and high capacitance even with thinner dielectric layers and increased stack thickness, suppressing crack formation and maintaining structural integrity.
Implementation Method 1
average diameters of dielectric grains included in the first and second cover layers are different from each other, resulting in varying sintering temperatures that align the sintering contraction of the capacitance and cover portions
Data Source
AI summary
An electronic component includes a body including a capacitance portion having dielectric layers formed of a dielectric material, internal electrodes and a cover portion covering at least one surface of the capacitance portion, the cover portion including cover layers formed of a dielectric material, the cover portion including a plurality of first and second cover layers that are stacked alternately, and an external electrode disposed on the body, the external electrode connected to the internal electrodes, wherein average diameters of dielectric grains included in the first and second cover layers are different from each other.