Polymeric Outer Layer for 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 reproducible and dense polymeric outer layers with good edge coverage, due to issues with in-situ polymerization and electrochemical polymerization processes, which often result in inhomogeneous layers and high contact resistances.
Innovation Solution
A method using dispersions containing particles of conductive polyaniline and/or polythiophene with an average diameter of 70-500 nm, along with a binder, to form a dense polymeric outer layer on electrolytic capacitors, where the particle diameter distribution is carefully controlled to ensure complete edge and corner coverage.
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 manufacturing complexity increases and edge coverage becomes insufficient
Solution Approach 1:
The patent applies a polymeric outer layer using a dip-coating process before final assembly and testing. This preliminary application ensures that the protective layer is in place before mechanical stresses occur during encapsulation, preventing damage to the dielectric and maintaining low residual current without requiring complex post-processing steps
2Strength
If in-situ polymerization is used to form a thick polymeric outer layer, then mechanical protection is improved, but manufacturing precision deteriorates due to inhomogeneous layer formation
Solution Approach 1:
The patent uses a binder material as an intermediary substance that facilitates uniform distribution of conductive polymer particles throughout the polymeric outer layer. This binder acts as a matrix that holds the particles in place and ensures homogeneous coverage, including at edges and corners, without requiring complex coordination of process parameters
3Reliability
If electrochemical polymerization is used to form a dense outer layer, then electrical conductivity is improved, but device complexity increases due to additional contacting steps
Solution Approach 1:
The patent replaces the electrochemical polymerization process with a mechanical dip-coating process. Instead of requiring electrical contact and electrochemical reactions, the conductive polymer particles are mechanically applied and distributed throughout the polymeric outer layer using a binder, achieving similar electrical conductivity without the complexity of electrochemical equipment and processes
4Productivity
If binder materials are added to build up layers more quickly, then productivity is improved, but electrical conductivity deteriorates due to hindered polymerization
Solution Approach 1:
The patent creates a composite polymeric outer layer that combines conductive polymer particles with a binder material. The conductive particles (such as polyacetylene, polythiophene, or polyaniline) provide the electrical conductivity pathway, while the binder provides structural integrity and enables homogeneous distribution. This composite structure maintains low ESR despite the presence of binder material
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 allows for the production of capacitors with significantly reduced residual currents and ESR, achieving robustness against mechanical stress and high electrical conductivity, with ESR measured at less than 50 mΩ at 100 kHz and residual currents minimized.
Implementation Method 1
A method using dispersions containing particles of conductive polyaniline and/or polythiophene with an average diameter of 70-500 nm, along with a binder, to form a dense polymeric outer layer on electrolytic capacitors
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 of the capacitor
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
Data Source
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AI summary
Method for preparing an electrolyte condenser (EC) in which a dispersion (D) is applied to a condenser body (1) comprising at least a porous electrode body (2), of electrode material; a dielectric (3) covering the surface of the electrode material; and a solid electrolyte (4) at least partly consisting of an electrically conductive material that covers, at least partly, the dielectric surface. Method for preparing an electrolyte condenser (EC) in which a dispersion (D) is applied to a condenser body (1) comprising at least a porous electrode body (2), of electrode material; a dielectric (3) covering the surface of the electrode material; a solid electrolyte (4) at least partly consisting of an electrically conductive material that covers, at least partly, the dielectric surface. (D) consists at least partly of an electrically conductive polymer (P); a binder and a dispersion agent; where (P) contains at least one optionally substituted polyaniline and/or polythiophene with repeating units (I) and/or (II), and for forming an electrically conductive polymer external layer, the dispersion agent is at least partly removed and/or the binder is hardened. The new feature is that the particles of conductive polymer in the dispersion have mean diameter 70-500 nm. A : 1-5C alkylene, optionally substituted; R, same or different, : 1-18C linear or branched alkyl, 5-12C cycloalkyl, 6-14C aryl, 7-18C aralkyl or 1-4C hydroxyalkyl, all optionally substituted, or hydroxy; and x : 0-8. An independent claim is also included for an EC prepared by the new method. [Image].