Solid Electrolytic Capacitor Corner Protection
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Solution Overview
Problem
Conventional solid electrolytic capacitors face issues with increased leakage current due to damage in corner parts caused by external and internal stress, leading to reduced capacitance density and adhesiveness problems between the porous sintered body and dielectric layer.
Innovation Solution
A solid electrolytic capacitor design featuring a porous sintered anode body with an uneven distribution of insulating material or silane compound in corner parts, which acts as a protective layer to reduce damage and enhance adhesiveness, thereby reducing leakage current while maintaining capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric layer is formed by anodization of the porous sintered body, then the capacitance density is improved, but the leakage current increases due to damage in corner parts
Solution Approach 1:
The patent applies local quality by forming a protective layer specifically at the corner parts of the porous sintered body where stress concentration occurs. This protective layer has different properties (higher insulation and mechanical strength) than the bulk material, locally addressing the vulnerability of corner parts while maintaining the overall capacitance density through uniform dielectric layer formation across the entire surface.
Solution Approach 2:
The protective layer is formed in advance before the dielectric layer formation process. This preliminary action prevents damage to corner parts during subsequent anodization and assembly processes, ensuring that the dielectric layer can be formed uniformly without defects that would cause leakage current.
2Speed
If the porous sintered body is used as anode body, then the frequency characteristics are improved, but the adhesiveness between the porous sintered body and dielectric layer deteriorates
Solution Approach 1:
The protective layer acts as an intermediary between the porous sintered body and the dielectric layer. It provides a stable interface that enhances adhesion while allowing the porous structure to maintain its frequency characteristics. The protective layer mediates the interaction between the two layers, preventing direct contact issues between the porous surface and dielectric material.
3Reliability
If the corner part of the porous sintered body is protected, then the leakage current is reduced, but the capacitance density decreases
Solution Approach 1:
The protective layer is applied locally only at corner parts rather than uniformly across the entire surface. This localized approach minimizes the volume occupied by the protective layer, ensuring that the majority of the porous sintered body surface remains available for capacitance formation, thus maintaining high capacitance density while providing targeted protection against leakage current.
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
The uneven distribution of protective material in corner parts effectively suppresses leakage current and improves pressure resistance, maintaining capacitance density and reducing the maximum value of leakage current by 31.1 μA compared to comparative examples.
Implementation Method 1
The dielectric layer is formed, for example, by anodization of the porous sintered body
Implementation Method 2
an insulating material disposed on a surface of the dielectric layer... a silane compound disposed on a surface of the dielectric layer
Data Source
AI summary
A solid electrolytic capacitor includes a capacitor element. The capacitor element includes an anode body that is a porous sintered body, a dielectric layer disposed on a surface of the porous sintered body, an insulating material disposed on a surface of the dielectric layer, and a solid electrolyte layer disposed on a surface of the insulating material. The capacitor element has at least one corner part. An amount of the insulating material disposed in the at least one corner part of the capacitor element is larger than an amount of the insulating material disposed in a center part of the capacitor element.