Multilayer Capacitor Curved Corners Margin Density
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving high capacitance and reliability due to stepped portions between internal electrodes and dielectric layers, leading to warpage and reduced moisture resistance, especially when trying to reduce size and increase integration density.
Innovation Solution
A multilayer capacitor design with curved corners and varying internal electrode lengths, where the margin conditions of 0.8≤Tg/Wg≤1.2 and 1≤δ/Wg≤1.2 are satisfied, and the inclusion of needle-type pores in the margin region with different densities, to enhance capacitance and moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the dielectric layer is reduced and the number of dielectric layers is increased to achieve high capacitance and reduced size, then the capacitance increases and size decreases, but stepped portions are formed between internal electrodes and dielectric layers causing warpage and reduced reliability
Solution Approach 1:
The patent applies local quality by creating different margin widths in different regions of the capacitor. The margin width is increased at corners and edges where stepped portions are most problematic, while maintaining standard margins in central regions. This localized approach addresses warpage and reliability issues specifically where they occur most frequently without compromising overall capacitance density.
Solution Approach 2:
The patent implements preliminary action by pre-forming increased margin widths at corner and edge regions during the manufacturing process, before the capacitor is put into service. This preventive measure ensures that stepped portions do not cause warpage or reliability failures during operation, as the structural compensation is already in place.
2Quantity of substance
If the number of internal electrodes is increased to achieve high capacitance, then the capacitance increases, but the complexity of managing stepped portions and maintaining reliability increases
Solution Approach 1:
The patent simplifies the overall structure by applying local quality - instead of uniformly increasing margins throughout the entire capacitor, it selectively increases margins only at corner and edge regions where stepped portions cause problems. This localized approach reduces structural complexity compared to a uniform design while still addressing reliability issues effectively.
3Volume of moving object
If side surface margin portions are made thinner to reduce overall capacitor size, then the size decreases, but the moisture resistance reliability deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality - it maintains thicker margin widths at corner and edge regions where moisture resistance is most critical, while allowing thinner margins in central regions to reduce overall size. This selective approach preserves moisture resistance reliability at vulnerable locations without sacrificing size reduction benefits.
Solution Approach 2:
The patent employs asymmetry by creating non-uniform margin width distribution throughout the capacitor structure. Corner and edge regions have increased margin widths for enhanced moisture resistance, while central regions have reduced margins for size optimization. This asymmetric design allows simultaneous achievement of compact size and reliable moisture protection.
Data Source
AI summary
A multilayer capacitor includes a body, a plurality of internal electrodes, and external electrodes. The corners of the cover portions of the body include curved surfaces, a length of each of internal electrodes disposed in the cover portions among the plurality of internal electrodes is smaller than a length of an internal electrode disposed in a central portion, and when a distance from a surface of the body to a closest internal electrode among the plurality of internal electrodes is defined as a margin, a portion of the margin region, located directly above or below the internal electrodes disposed in the cover portions in the stacking direction, includes at least two layers including different densities of dielectric layers.