Solid Electrolytic Capacitor with PEG Intermediate Layer
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Solution Overview
Problem
Solid electrolytic capacitors face challenges in reducing equivalent series resistance (ESR) due to high contact resistance between the solid electrolyte and dielectric layers, despite the introduction of intermediate layers like organic silane, which has not sufficiently addressed the issue.
Innovation Solution
Incorporating a polyethylene glycol intermediate layer between the dielectric and electrolyte layers, formed by anodizing a valve metal anode and coating with a conductive polymer, enhances adhesiveness and reduces contact resistance, thereby lowering ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an organic silane intermediate layer is introduced between the solid electrolyte and dielectric layer, then the contact resistance is reduced, but the ESR reduction is insufficient and limited
Solution Approach 1:
The patent introduces a polyethylene glycol (PEG) intermediate layer between the dielectric layer and conductive polymer electrolyte layer. This PEG layer acts as a mediator that forms chemical bonds (hydrogen bonding) with both the dielectric layer and the conductive polymer, creating effective adhesion and reducing contact resistance. The PEG intermediate layer overcomes the limitation of organic silane by providing sufficient ESR reduction through its unique molecular structure and bonding capabilities.
Solution Approach 2:
The patent specifies precise parameter ranges for the PEG intermediate layer to optimize performance: molecular weight between 400-1200 (preferably 800-1000) and film thickness between 0.5-20 nm. By controlling these parameters, the patent achieves the optimal balance between adhesion strength and contact resistance reduction, thereby effectively lowering ESR without excessive complexity.
2Device complexity
If the dielectric layer and electrolyte layer are directly contacted, then the structure is simple, but the contact resistance is high leading to increased ESR
Solution Approach 1:
The PEG intermediate layer serves as a thin mediator that bridges the dielectric layer and conductive polymer electrolyte layer. Despite adding a layer, the overall structure remains simple because the PEG layer is extremely thin (0.5-20 nm) and can be formed by a straightforward dip-coating process. This intermediate layer dramatically reduces contact resistance by forming chemical bonds with both adjacent layers, achieving low ESR without significant structural complexity.
Solution Approach 2:
The patent utilizes a thin film approach by employing a PEG intermediate layer with thickness of only 0.5-20 nm. This ultra-thin film provides sufficient adhesion and contact resistance reduction while maintaining structural simplicity. The thin film nature of the PEG layer ensures it does not add significant complexity to the overall capacitor structure, yet effectively solves the high contact resistance problem.
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 use of a polyethylene glycol intermediate layer effectively reduces ESR in solid electrolytic capacitors by improving adhesiveness between the dielectric and electrolyte layers, resulting in a more efficient capacitor with lower ESR values.
Implementation Method 1
it is thought that the reason the adhesiveness can be increased is that the polyethylene glycol forms chemical bonding, such as hydrogen bonding, between the dielectric and the conductive polymer
Implementation Method 2
a dielectric layer formed by anodizing the anode
Data Source
AI summary
The objective of the current invention is to provide a solid electrolytic capacitor element with low equivalent series resistance. In this solid electrolytic capacitor element, an anode including a porous sintered body, and a dielectric layer are sequentially formed on an anode lead so as to cover a portion of the anode lead. An intermediate layer including polyethylene glycol is formed on the dielectric layer so as to cover an area around the dielectric layer. An electrolyte layer that includes polypyrrole is formed on the intermediate layer so as to cover an area around the intermediate layer. A cathode that includes: a first electrically conductive layer mainly including graphite particles and a second electrically conductive layer mainly including silver particles is formed on the electrolyte layer so as to cover an area surrounding the electrolyte layer.