Solid Electrolytic Capacitor with Varying Dielectric Thickness
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Solution Overview
Problem
Conventional solid electrolytic capacitors face challenges in reducing leakage current while minimizing the decrease in capacitance, as the dielectric layer is prone to stress-related defects during assembly, leading to cracks and increased leakage current.
Innovation Solution
The capacitors are designed with a porous sintered body anode having varying dielectric layer thicknesses in different regions to distribute stress effectively, with thicker layers in regions susceptible to stress from the anode lead and resin package, and thinner layers in less susceptible areas to maintain capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dielectric layer thickness is increased in stress-prone regions to prevent cracks, then leakage current is reduced, but capacitance decreases
Solution Approach 1:
The patent applies local quality by creating a non-uniform dielectric layer thickness distribution where the thickness is increased specifically in stress-prone regions (near anode lead embedding and at corner portions) while maintaining thinner thickness in less stressed regions. This localized thickness variation prevents cracks in critical areas without unnecessarily reducing capacitance across the entire anode surface, thus resolving the contradiction between reducing leakage current and maintaining capacitance.
2Reliability
If the dielectric layer thickness is uniformly increased to prevent cracks, then reliability improves, but capacitance decreases significantly
Solution Approach 1:
The patent implements local quality by forming a dielectric layer with spatially varying thickness where t1 (thickness near anode lead) ≥ t2 (thickness at corners) ≥ t3 (thickness in other regions). This localized thickening approach provides crack prevention exactly where stress concentrations occur while minimizing the overall volume of dielectric material, thereby maintaining higher capacitance compared to uniform thickening.
Solution Approach 2:
The patent segments the anode surface into distinct regions with different dielectric thickness requirements: a first region near the anode lead embedding, second regions at corner portions, and third regions in other areas. By segmenting the dielectric layer formation process and applying different thicknesses to different segments, the patent achieves crack prevention in critical areas while preserving capacitance in less critical areas.
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 design reduces leakage current by dispersing stress across the dielectric layer and minimizes capacitance loss by optimizing dielectric layer thickness distribution, enhancing the overall performance of the solid electrolytic capacitors.
Implementation Method 1
a dielectric layer formed by anodizing the anode 101
Data Source
AI summary
An anode includes a first region adjacent to a root of an anode lead, a second region at a corner of one end surface of the anode, a third region between the first region and the second region, and a fourth region in the interior of the anode into which the anode lead is embedded. The thicknesses of a dielectric layer in the first region and the second region are greater than the thicknesses of the dielectric layer in the third region and the fourth region.