Solid Electrolytic Capacitor Coupling Agent Layer Leakage Current
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Solution Overview
Problem
Solid electrolytic capacitors face challenges in reducing leakage current and ensuring long-term reliability, especially under high-temperature conditions, due to incomplete coating and defects in the dielectric layer.
Innovation Solution
A solid electrolytic capacitor design that includes a coupling agent layer with a first coupling agent having a phosphonic acid group and a second silane coupling agent, applied in specific sequences to enhance adhesion and coating density between the dielectric and conductive polymer layers, reducing leakage current and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the dielectric layer is reduced to increase capacitance, then capacitance increases, but leakage current increases due to incomplete coating and defects
Solution Approach 1:
A coupling agent layer is introduced as an intermediary between the dielectric layer and the conductive polymer layer. This coupling agent layer fills defects and pinholes in the dielectric layer, providing a barrier that prevents leakage current while maintaining the thin dielectric layer structure for high capacitance.
Solution Approach 2:
The patent uses a composite structure consisting of multiple layers: dielectric layer, coupling agent layer, and conductive polymer layer. Each layer serves a specific function, and their combination achieves both high capacitance and low leakage current by addressing different aspects of the problem separately.
2Quantity of substance
If the surface area of the anode is increased to increase capacitance, then capacitance increases, but complete coating of the dielectric layer becomes difficult
Solution Approach 1:
The coupling agent layer acts as an intermediary that can penetrate and fill the complex surface structures of high-surface-area anodes, including pores and irregularities. This enables complete coverage even on surfaces with large surface area, ensuring no uncoated regions remain.
3Strength
If a single coupling agent is used to improve adhesion, then adhesion improves, but reliability under high-temperature load test is insufficient
Solution Approach 1:
The patent employs a composite coupling agent system with two different coupling agents having distinct functions. The first coupling agent provides primary adhesion and fills defects, while the second coupling agent enhances thermal stability and prevents degradation under high-temperature conditions. This composite approach achieves both adhesion and high-temperature reliability.
Solution Approach 2:
Different regions of the coupling agent layer have different compositions and functions. The first coupling agent addresses adhesion and defect filling, while the second coupling agent specifically addresses high-temperature stability. This local differentiation of material properties achieves multiple objectives 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
The proposed design effectively reduces leakage current and enhances reliability under high-temperature load tests by ensuring a dense and uniform coating of the dielectric layer, leading to improved capacitance retention and reduced leakage current.
Implementation Method 1
the coupling agent layer contains a first coupling agent having a phosphonic acid group and a second coupling agent which is a silane coupling agent
Data Source
AI summary
Provided are a solid electrolytic capacitor including an anode, a dielectric layer provided on a surface of the anode, a coupling agent layer provided on the dielectric layer, a conductive polymer layer provided on the coupling agent layer, and a cathode layer provided on the conductive polymer layer, wherein the coupling agent layer contains a first coupling agent having a phosphonic acid group and a second coupling agent which is a silane coupling agent, and a method for manufacturing the solid electrolytic capacitor.