Solid Electrolytic Capacitor With Thickened Peripheral Cathode
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Solution Overview
Problem
Existing solid electrolytic capacitors face issues with insufficient withstand voltage and adhesion between the solid electrolyte layer and the valve-action metal substrate, particularly at the outer peripheral portions due to electric field concentration and inadequate masking material coverage.
Innovation Solution
A solid electrolytic capacitor design featuring a valve-action metal substrate with a dielectric layer and a mask layer made of insulating material, where the cathode layer includes a solid electrolyte layer with a first layer filling pores, a second layer extending along the outer peripheral portion, and a third layer covering the second layer, enhancing both withstand voltage and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mask layer is formed to cover the periphery of the valve-action metal substrate, then the adhesion between the solid electrolyte layer and the substrate is improved, but the electric field concentration at the outer peripheral portion causes insufficient withstand voltage
Solution Approach 1:
The patent applies different properties to different regions of the solid electrolyte layer. The outer peripheral portion has a greater thickness than the inner portion, creating local quality variation. This thicker outer region specifically addresses the electric field concentration problem at the periphery while maintaining adequate adhesion in the inner region where the mask layer contacts the substrate.
Solution Approach 2:
The patent transitions from a uniform two-dimensional solid electrolyte layer to a three-dimensional structure with varying thickness. By adding the thickness dimension and creating a gradient structure (thinner in the center, thicker at the edges), the patent simultaneously improves both adhesion and withstand voltage without the trade-off present in uniform thickness designs.
2Ease of manufacture
If the solid electrolyte layer is formed only within the region surrounded by the mask layer, then the manufacturing process is simplified, but the withstand voltage at the outer peripheral portion becomes insufficient
Solution Approach 1:
The solid electrolyte layer is formed with locally different thicknesses - a thinner inner portion and a thicker outer peripheral portion. This local quality variation allows the outer region to withstand higher electric fields while the inner region maintains good adhesion, thereby improving overall reliability without significantly complicating the manufacturing process.
Solution Approach 2:
The mask layer is formed in advance to define the region where the solid electrolyte layer will be deposited. This preliminary action guides the formation process and ensures that the solid electrolyte layer achieves the desired thickness distribution, with the outer peripheral portion being thicker to handle electric field concentration before final assembly occurs.
3Device complexity
If a uniform thickness solid electrolyte layer is used, then the manufacturing process is simplified, but the adhesion at the outer peripheral portion is insufficient leading to peeling in high temperature and humidity environments
Solution Approach 1:
The solid electrolyte layer features local quality variation with different thicknesses in different regions. The outer peripheral portion has greater thickness to ensure adequate adhesion and prevent peeling, while the inner portion can be thinner. This resolves the contradiction between structural simplicity and adhesion reliability in harsh environments.
Solution Approach 2:
The thicker outer peripheral portion of the solid electrolyte layer acts as a cushioning layer that prevents peeling before it occurs. This prior cushioning structure compensates for the potential adhesion weaknesses at the edges where the mask layer contacts the substrate, ensuring reliability in high temperature and humidity conditions.
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 proposed design significantly improves the withstand voltage and adhesion between the solid electrolyte layer and the valve-action metal substrate, reducing the likelihood of peeling in high temperature and humidity environments and enhancing the reliability of the capacitor.
Implementation Method 1
a dielectric layer having pores on at least one main surface of the valve-action metal substrate
Implementation Method 2
a first layer filling the pores of the dielectric layer
Data Source
AI summary
A solid electrolytic capacitor that includes a valve-action metal substrate including a dielectric layer having pores on at least one main surface thereof, a mask layer made of an insulating material and covering a periphery of the main surface of the valve-action metal substrate, and a cathode layer on the dielectric layer at least within a region surrounded by the mask layer. The cathode layer includes a solid electrolyte layer on the dielectric layer, and the solid electrolyte layer includes a first layer filling the pores of the dielectric layer, a second layer on the dielectric layer and along an outer peripheral portion of the region surrounded by the mask layer, the second layer being made of a material same as or different from that of the first layer, and a third layer covering the second layer and the dielectric layer.