Solid Electrolytic Capacitor Leakage Current Reduction
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Solution Overview
Problem
Conventional solid electrolytic capacitors using in situ-polymerized polymers exhibit high leakage current and fail at high voltages, and while PEDOT:PSS dispersions reduce leakage current, they show a slow decrease over time and are not effective under varying conditions such as high temperature and low humidity.
Innovation Solution
A capacitor assembly with a sintered porous anode body, a dielectric layer, a pre-coat layer formed from an organometallic compound, and a solid electrolyte comprising an inner layer of in situ-polymerized conductive polymer and an outer layer of pre-polymerized conductive polymer particles, which maintains low leakage current and fast decay even under extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If in situ-polymerized conductive polymer is used as solid electrolyte, then equivalent series resistance is low, but leakage current is high and capacitor fails at high voltages
Solution Approach 1:
The solid electrolyte is segmented into three distinct layers: an inner layer of in situ-polymerized conductive polymer for low ESR, a middle layer of organometallic compound pre-coat for adhesion and stability, and an outer layer of pre-polymerized conductive polymer particles for reduced leakage current. This segmentation allows each layer to fulfill its specific function, resolving the contradiction between low ESR and low leakage current.
Solution Approach 2:
The invention uses a composite electrolyte structure combining different conductive polymer materials with distinct properties. The inner layer uses in situ-polymerized polymer for conductivity, while the outer layer uses pre-polymerized particles for stability and low leakage. This composite approach integrates the advantages of different materials to achieve both low ESR and low leakage current.
2Reliability
If PEDOT:PSS dispersion is used as solid electrolyte, then leakage current is reduced, but the decrease in leakage current over time is slow and performance degrades under high temperature and low humidity conditions
Solution Approach 1:
The organometallic compound pre-coat layer is applied in advance to the dielectric surface before applying the conductive polymer layers. This preliminary action creates a stable, adherent base layer that prevents degradation and maintains performance stability under extreme conditions, addressing the time-dependent performance issues of PEDOT:PSS dispersions.
Solution Approach 2:
The invention changes the chemical composition and structural parameters of the electrolyte system by introducing an organometallic compound pre-coat layer and using in situ-polymerized conductive polymer instead of PEDOT:PSS dispersion. This parameter change fundamentally improves the thermal and humidity stability, enabling fast leakage current decay and sustained performance under extreme 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 capacitor assembly achieves low leakage current values (≤20 μA) and rapid decay (>50% reduction in 180 seconds) even at high temperatures (up to 150°C) and low humidity, maintaining effective electrical performance under various conditions.
Implementation Method 1
applying a solution to the anode that includes an organometallic compound
Implementation Method 2
polymerizing a conductive polymer precursor monomer in the presence of an oxidative catalyst to form an inner solid electrolyte layer
Data Source
AI summary
A capacitor assembly that is capable of exhibiting good electrical properties even under a variety of conditions is provided. More particularly, the capacitor contains a capacitor element that includes a sintered porous anode body, a dielectric that overlies the anode body, and a pre-coat layer that overlies the dielectric and is formed from an organometallic compound. A solid electrolyte overlies the pre-coat layer that contains an inner layer and an outer layer, wherein the inner layer is formed from an in situ-polymerized conductive polymer and the outer layer is formed from pre-polymerized conductive polymer particles.