Conductive Polymer Dispersion for Capacitor Edge Coverage
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Solution Overview
Problem
Solid electrolytic capacitors with conductive polymer cathodes face challenges in achieving effective coverage of edges and corners, leading to high DC leakage current and reliability issues in humid environments, and existing solutions either compromise ESR stability or introduce brittleness in the polymeric outer film.
Innovation Solution
A conductive polymer dispersion with a bimodal size distribution of conductive polymer:polyanion complex particles is applied, featuring first particles with an average diameter of 1 micron to 10 microns and second particles with an average diameter of 1 nm to 600 nm, enhancing corner and edge coverage through improved interfacial adhesion and film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solid particles of conductive polymer are added to the dispersion, then edge and corner coverage is improved, but dispersion stability deteriorates and viscosity increases
Solution Approach 1:
The invention changes the particle size parameter by using pre-polymerized conductive polymer particles with controlled diameter of 0.1-10 micrometers, and adjusts the polyanion concentration parameter to 1-10 wt% relative to conductive polymer, optimizing both coverage and dispersion stability
Solution Approach 2:
The invention creates a composite system by combining pre-polymerized conductive polymer particles with polyanion in a dispersion medium, where the polyanion acts as a stabilizing agent that prevents particle aggregation while maintaining good edge and corner coverage
2Manufacturing precision
If solid particles of conductive polymer are added to the dispersion, then edge and corner coverage is improved, but ESR performance deteriorates
Solution Approach 1:
The invention optimizes particle size parameters (0.1-10 micrometers) and polyanion concentration (1-10 wt%) to achieve a balance between coverage and ESR performance, preventing particle aggregation that would cause high ESR while maintaining edge and corner coverage
3Manufacturing precision
If crosslinker is applied to improve polymer coverage on corners and edges, then coverage is improved, but ESR shift increases in high humidity environment
Solution Approach 1:
The invention extracts and eliminates the crosslinker component from the system, achieving good edge and corner coverage through pre-polymerized particles with controlled size and polyanion stabilization without the harmful effects of crosslinking agents on ESR stability in humid conditions
4Manufacturing precision
If solid particles are added to improve coverage, then coverage is improved, but mechanical integrity of interfaces deteriorates
Solution Approach 1:
The invention creates a composite dispersion system where pre-polymerized conductive polymer particles are stabilized by polyanion, achieving good coverage while maintaining mechanical integrity through proper particle size control and dispersion stabilization without crosslinking
Data Source
AI summary
A dispersion comprising first particles comprising conductive polymer and polyanion and second particles comprising the conductive polymer and said polyanion wherein the first particles have an average particle diameter of at least 1 micron to no more than 10 microns and the second particles have an average particle diameter of at least 1 nm to no more than 600 nm.