Polymeric Outer Layer for Solid Electrolytic Capacitors
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Solution Overview
Problem
Current methods for producing solid electrolytic capacitors with low equivalent series resistance (ESR) and low residual current face challenges in achieving dense, uniformly thick polymeric outer layers with good edge coverage, as existing processes are complex, prone to inhomogeneity, and often result in high contact resistances or rough surfaces.
Innovation Solution
A method involving a dispersion containing particles of polyaniline and/or polythiophene with diameters less than 700 nm, a binder, and solid particles with diameters between 0.7 μm and 20 μm is used to form a conductive polymeric outer layer, ensuring a solids content of at least 5% by weight, which improves edge and corner coverage while smoothing roughness and reducing ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If in-situ polymerization is used to form a thick polymeric outer layer, then mechanical protection is improved, but the layer becomes inhomogeneous with poor edge coverage
Solution Approach 1:
The patent applies a primer layer containing conductive polymer particles and binder to the capacitor anode before the main polymeric outer layer. This preliminary coating ensures uniform coverage on the porous surface, creating a foundation that prevents inhomogeneity and poor edge coverage during subsequent polymerization processes.
Solution Approach 2:
The patent uses composite materials combining conductive polymer particles (polyaniline, polythiophene) with binder materials to form the outer layer. This composite approach allows the layer to achieve both mechanical protection and electrical conductivity while maintaining homogeneity and good edge coverage.
2Strength
If multiple coating cycles are used to build up layer thickness, then mechanical buffer effect is improved, but manufacturing complexity and process susceptibility increase
Solution Approach 1:
The patent applies a primer layer containing conductive polymer particles and binder to the capacitor anode before the main polymeric outer layer. This preliminary coating ensures uniform coverage on the porous surface, creating a foundation that prevents inhomogeneity and poor edge coverage during subsequent polymerization processes.
Solution Approach 2:
The patent uses composite materials combining conductive polymer particles (polyaniline, polythiophene) with binder materials to form the outer layer. This composite approach allows the layer to achieve both mechanical protection and electrical conductivity while maintaining homogeneity and good edge coverage.
3Productivity
If binder materials are added to build up layers quickly, then productivity is improved, but electrical conductivity decreases due to hindered polymerization
Solution Approach 1:
The patent uses composite materials combining conductive polymer particles (polyaniline, polythiophene) with binder materials to form the outer layer. This composite approach allows the layer to achieve both mechanical protection and electrical conductivity while maintaining homogeneity and good edge coverage.
Solution Approach 2:
The patent creates different functional zones within the outer layer: a primer layer with binder and conductive particles for adhesion and initial conductivity, and an outer polymeric layer for mechanical protection. Each zone has optimized properties for its specific function, allowing overall system performance to meet both mechanical and electrical requirements.
4Stability of the object's composition
If the polymeric outer layer is made thicker to improve mechanical stability, then stability against loads is improved, but ESR increases
Solution Approach 1:
The patent uses composite materials combining conductive polymer particles (polyaniline, polythiophene) with binder materials to form the outer layer. This composite approach allows the layer to achieve both mechanical protection and electrical conductivity while maintaining homogeneity and good edge coverage.
Solution Approach 2:
The patent creates different functional zones within the outer layer: a primer layer with binder and conductive particles for adhesion and initial conductivity, and an outer polymeric layer for mechanical protection. Each zone has optimized properties for its specific function, allowing overall system performance to meet both mechanical and electrical requirements.
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 approach results in solid electrolytic capacitors with low ESR, low residual current, and robust mechanical stability, as the polymeric outer layer forms a dense, uniformly thick layer that effectively covers capacitor edges and corners, reducing the risk of high residual currents and electrical breakdowns.
Implementation Method 1
A method is described for producing solid electrolytic capacitors with low equivalent series resistance and low residual current... a dispersion a) is applied which contains at least particles b) of an electrically conductive polymer
Implementation Method 2
π-conjugated polymers are particularly suitable as solid electrolytes due to their high electrical conductivity... Poly(3,4-ethylenedioxythiophene) as a replacement for manganese dioxide or charge transfer complexes in solid electrolytic capacitors lowers the equivalent series resistance
Implementation Method 3
Stability against such loads and thus a low residual current can be achieved primarily through an approx. 5-50 μm thick outer layer made of conductive polymers on the capacitor anode. Such a layer serves as a mechanical buffer between the capacitor anode and the cathode-side contact
Implementation Method 4
European patent EP-A-340 512 describes the production of a solid electrolyte from 3,4-ethylene-1,2-dioxythiophene and the use of its cationic polymer, produced by oxidative polymerization, as a solid electrolyte in electrolytic capacitors
Data Source
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AI summary
Preparation of electrolyte condenser comprises introducing a porous electrode body of an electrode material, dielectric and a solid electrolyte, on a condenser body (1); applying a dispersion containing at least an electrically conductive polymer particle having at least optionally substituted polyaniline and/or polythiophene with thiophene repeating units (I) or (II), binders, a dispersing agent and a solid particle; and preparing an electrically conductive polymer outer layer by optionally removing the dispersing agent or hardening the binder. Preparation of electrolyte condenser comprises introducing a porous electrode body of an electrode material, dielectric and a solid electrolyte containing at least a electrically conductive material, which partially or completely covers the dielectric surface, on a condenser body (1); applying a dispersion containing at least an electrically conductive polymer particle having at least optionally substituted polyaniline and/or polythiophene with thiophene repeating units of formula (I) or (II), binders, a dispersing agent and a solid particle with a diameter of 0.7-20 mu m; and preparing an electrically conductive polymer outer layer by optionally removing the dispersing agent or hardening the binder; where the concentration of the conductive polymer particle with diameter of less than 700 nm is at least 5 wt.%. A = optionally substituted 1-5C alkylene; R = optionally substituted 1-18C alkyl, 5-12C cycloalkyl, 6-14C aryl, 7-18C aralkyl, 1-4C hydroxyalkyl or hydroxyl group; and x = 0-8. The groups of R are bound at A. An independent claim is included for the electrolyte condenser obtained by the above process. [Image].