Doped Solid Electrolyte Capacitor Layer for Low Leakage and ESR
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Solution Overview
Problem
Existing electrolytic capacitor elements face issues with high leakage current and increased equivalent series resistance due to the insulation mechanism of conductive polymer layers, particularly at corners and ridges, which are not adequately covered, leading to concentrated electric fields.
Innovation Solution
The electrolytic capacitor element incorporates a dual-layered solid electrolyte structure with a first conductive polymer doped with a first dopant and a second conductive polymer doped with a second dopant, where the second layer is more likely to be dedoped and selectively disposed at locations prone to leakage current, acting as a local self-healing layer, while the first layer maintains conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second conductive polymer layer is added to cover the cut face of the anode body for insulation, then leakage current is reduced, but the conductivity of the entire second conductive polymer layer decreases leading to increased equivalent series resistance
Solution Approach 1:
The patent applies local quality by creating a multi-layered solid electrolyte structure where different regions have different properties. The first conductive polymer layer provides baseline conductivity, while the second conductive polymer layer (with different dopant concentration or composition) provides enhanced insulation at specific locations (cut faces and corners) where leakage current is most problematic. This localized differentiation allows the structure to simultaneously reduce leakage current while maintaining overall conductivity.
Solution Approach 2:
The patent employs composite materials by combining multiple conductive polymer layers with different dopant concentrations or compositions. The first layer uses a standard dopant concentration for general conductivity, while the second layer uses a modified dopant concentration or different dopant type to provide both insulation and conductivity. This composite structure resolves the contradiction between needing insulation (to reduce leakage) and maintaining conductivity (to avoid increased ESR).
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 suppresses leakage current without significantly increasing equivalent series resistance, enhancing the reliability and performance of the capacitor.
Implementation Method 1
a first layer including a first conductive polymer doped with a first dopant
Implementation Method 2
a second layer including a second conductive polymer doped with a second dopant, the second conductive polymer is more likely to be dedoped than the first conductive polymer
Data Source
AI summary
An electrolytic capacitor element that includes: an anode having a front end face and a base end face; a dielectric layer on at least one main face of the anode but excluding the base end face; a mask layer on the dielectric layer adjacent the base end face; and a cathode on the dielectric layer on the front end face side from the mask layer, wherein the cathode includes a solid electrolyte layer and a conductive layer, the solid electrolyte layer includes a first layer including a first conductive polymer doped with a first dopant and a second layer including a second conductive polymer doped with a second dopant, the second layer is partially disposed in the plane of the solid electrolyte layer, and the second conductive polymer is more likely to be dedoped than the first conductive polymer.