Multilayer Conductive Polymer Electrolytic Capacitor ESR Reduction
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Solution Overview
Problem
Conventional electrolytic capacitors with conductive polymer layers face challenges in reducing equivalent series resistance (ESR) and suppressing leakage current due to difficulties in enhancing the covering properties and thickness of the conductive polymer layers, leading to inadequate performance in high-frequency applications.
Innovation Solution
The electrolytic capacitor incorporates a multilayer structure with a first and second conductive polymer layer, separated by an intermediate layer containing a cationic agent and an anionic agent, where the distribution of these agents between the regions facing each polymer layer enhances film-forming properties and coverage, allowing for increased thickness and reduced ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single conductive polymer layer is used, then the structure is simple, but the ESR is high and leakage current is high
Solution Approach 1:
The conductive polymer layer is divided into multiple layers (first conductive polymer layer and second conductive polymer layer) with an intermediate layer between them. This segmentation allows each layer to perform specific functions: the first layer provides initial coverage, the intermediate layer enhances adhesion and restores dielectric properties, and the second layer provides additional coverage and conductivity, collectively reducing ESR and leakage current while maintaining manageable structural complexity
Solution Approach 2:
An intermediate layer is introduced between the first and second conductive polymer layers. This intermediate layer contains cationic and anionic agents that enhance the adhesion between polymer layers and restore dielectric properties. The intermediate layer acts as a mediator that improves the overall performance of the capacitor by facilitating better interfacial contact and electrical properties between the conductive polymer layers
2Reliability
If the conductive polymer layer thickness is increased, then ESR is reduced, but the covering properties and film formation are inadequate
Solution Approach 1:
Instead of forming a single thick conductive polymer layer, the structure is segmented into multiple thinner layers separated by an intermediate layer. This allows for better film formation and covering properties at each stage, while the cumulative effect of multiple layers achieves the desired thickness for low ESR. Each layer can be optimized for its specific function rather than requiring one layer to accomplish all requirements
Solution Approach 2:
The intermediate layer with cationic and anionic agents serves as a mediator that enhances film formation and adhesion between conductive polymer layers. This intermediate layer ensures that subsequent polymer layers form properly and adhere well, solving the covering properties issue while enabling increased overall thickness for ESR reduction
3Strength
If a cross-linking agent is used before forming the polymer outer layer, then peeling is suppressed and covering properties are enhanced, but the ESR and leakage current performance is insufficient
Solution Approach 1:
The capacitor structure is segmented into multiple functional layers: conductive polymer layers for conductivity, an intermediate layer with cationic and anionic agents for adhesion and dielectric restoration, and a polymer outer layer for protection. This segmentation allows each layer to be optimized for its specific function, achieving both strong adhesion and low ESR with suppressed leakage current that a single-layer approach cannot accomplish
Solution Approach 2:
The intermediate layer containing cationic and anionic agents acts as a mediator between the conductive polymer layers and the polymer outer layer. This intermediate layer not only suppresses peeling through enhanced adhesion but also restores dielectric properties and enables better conductivity, thereby achieving both strong adhesion and improved ESR/leakage current performance simultaneously
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 configuration effectively reduces ESR and suppresses leakage current, improving the capacitor's performance by enhancing the conductivity and film-restoring properties of the dielectric layer, thereby addressing the limitations of conventional capacitors.
Implementation Method 1
The first intermediate layer includes a cationic agent and an anionic agent... the first region contains a greater amount of an anionic agent than the second region, and the second region contains a greater amount of a cationic agent than the first region
Data Source
AI summary
An electrolytic capacitor includes: an anode body; a dielectric layer; a first conductive polymer layer; a second conductive polymer layer; and a first intermediate layer. The dielectric layer is formed on the anode body. The first conductive polymer layer covers at least a part of the dielectric layer. The second conductive polymer layer covers at least a part of the first conductive polymer layer. The first intermediate layer is formed between the first conductive polymer layer and the second conductive polymer layer. The first intermediate layer includes both a cationic agent and an anionic agent, and the first intermediate layer has a first region and a second region, the first region facing the first conductive polymer layer, the second region facing the second conductive polymer layer. The first region contains a greater amount of the anionic agent than the second region, and the second region contains a greater amount of the cationic agent than the first region.