Electrolytic Capacitor Conductive Polymer Swelling Method
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Solution Overview
Problem
The dielectric layer in electrolytic capacitors formed by surface treatment on an anode foil has many defects, leading to insufficient film recoverability and leakage current issues, particularly due to the conditions used in forming the conductive solid layer containing a conductive polymer.
Innovation Solution
A method involving a first step of preparing a capacitor element with a dielectric layer, followed by impregnation with a processing solution containing a conductive polymer and a solvent, and a subsequent step of swelling the conductive polymer using a swelling agent while part of the solvent remains, to enhance film recoverability and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive solid layer is formed by impregnating with a dispersion of conductive polymer, then the capacitor achieves small size and high capacitance, but the film recoverability of the dielectric layer becomes insufficient and leakage current increases
Solution Approach 1:
The patent changes the physical state parameters of the conductive polymer by introducing a swelling step. The conductive polymer is transformed from a dry solid state to a swollen gel state by impregnating with a swelling agent (such as cyclic carbonate or chain carbonate). This parameter change allows the conductive polymer to better fill and recover the defects in the dielectric layer, improving film recoverability while suppressing leakage current.
Solution Approach 2:
The patent creates a composite structure by combining the conductive polymer with a swelling agent. The resulting material is a gel-like composite that maintains the conductive properties of the polymer while gaining the volume-expanding and defect-filling capabilities of the swelling agent. This composite material effectively addresses both the capacitance requirement and the leakage current issue.
2Manufacturing precision
If the dielectric layer is formed by surface treatment on an anode foil, then the capacitor structure is established, but the layer contains many defects that cause leakage current
Solution Approach 1:
The patent applies preliminary action by forming the conductive polymer layer on the dielectric layer before final assembly. The conductive polymer is deposited while the dielectric layer is still in place, allowing the polymer to conformally coat and fill surface defects. This preliminary coating action prevents leakage current paths from forming at defect sites.
Solution Approach 2:
The conductive polymer acts as an intermediary material between the anode and cathode. It not only provides the necessary electrical conductivity for the capacitor function but also serves as a defect-filling medium that seals imperfections in the dielectric layer, thereby eliminating leakage current pathways.
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 method results in an electrolytic capacitor with excellent film recoverability and suppressed leakage current, improving the capacitors' performance by ensuring the conductive polymer adheres uniformly to the dielectric layer.
Implementation Method 1
a third step of swelling the conductive polymer after the second step, by impregnating the capacitor element with a second processing solution including a swelling agent
Data Source
AI summary
A method for manufacturing an electrolytic capacitor includes: a first step of preparing a capacitor element including an anode having a dielectric layer; a second step of impregnating the capacitor element with a first processing solution including at least a conductive polymer and a first solvent; and a third step of swelling the conductive polymer after the second step, by impregnating the capacitor element with a second processing solution including a swelling agent while at least part of the first solvent remains in the capacitor element.