Multilayer Capacitor Rounded Edge Curvature Design
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) face challenges in miniaturization and high integration, leading to reduced reliability in breakdown voltage and humidity resistance due to complex fabrication processes and thin dielectric layers, which result in irregular internal electrode structures and voids.
Innovation Solution
A multilayer capacitor design with a body featuring a lamination structure of internal electrodes and dielectric layers, where the cover portions have rounded edges with specific curvature and margin conditions, ensuring increased effective volume and improved humidity resistance while maintaining high capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dielectric layers are thinned to laminate more layers and increase capacitance, then capacitance increases, but reliability deteriorates due to irregular internal electrode structures and voids
Solution Approach 1:
The patent applies curvature to the cover portions of the body by rounding the edges with a specific radius of curvature R. This curvature design prevents the formation of voids and irregularities at the corners and edges of the internal electrodes, thereby maintaining reliable electrical connections even when dielectric layers are thinned to increase capacitance.
Solution Approach 2:
The patent differentiates the structure between the central portion and cover portions of the body. The cover portions have rounded edges with specific curvature, while the central portion maintains its conventional structure. This local differentiation allows the patent to improve reliability at critical edge regions without compromising the overall capacitance enhancement achieved through thin dielectric layers.
2Volume of moving object
If side margin portion thickness is reduced to minimize body size, then miniaturization improves, but humidity resistance reliability deteriorates
Solution Approach 1:
By rounding the edges of the cover portions with a specific radius of curvature, the patent eliminates sharp corners where moisture accumulation and stress concentration typically occur. This curvature design maintains adequate margin thickness at critical regions while allowing overall miniaturization of the capacitor body.
3Stability of the object's composition
If internal electrode ends are bent to fill steps and eliminate voids, then connectivity improves, but reliability deteriorates due to irregular structural stretching
Solution Approach 1:
Instead of bending internal electrode ends to fill steps, the patent rounds the external edges of the body's cover portions. This curvature design naturally prevents void formation at electrode corners and edges, maintaining both connectivity and structural regularity without the need for electrode bending that causes stretching and reliability degradation.
Data Source
AI summary
A multilayer capacitor includes a body and external electrodes on external surfaces of the body. The body includes a plurality of internal electrodes alternately laminated with dielectric layers. The external electrodes are electrically connected to the internal electrodes. Edges of cover portions of the body are rounded. The rounded edges have a radius of curvature R and the body has a thickness T, such that R and T satisfy 10 μm≤R≤T/4. Among the plurality of internal electrodes, an internal electrode in each of the cover portions has a width less than that of an internal electrode of the central portion.