Conductive Polymer Capacitor Cathode with Dual Crosslinker System
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Solution Overview
Problem
Solid electrolytic capacitors using conductive polymer cathodes face challenges with ESR stability due to poor adhesion and mechanical weakening at high temperatures, leading to increased electrical resistance and performance deterioration.
Innovation Solution
A dual crosslinker system combining organofunctional silane and an organic compound with multiple epoxy or carboxylic acid groups is used to enhance the structural integrity of the conductive polymer cathode layer, improving adhesion and stability without increasing water absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymeric binders are added to enhance mechanical properties and adhesion of PEDOT-PSSA film, then adhesion and mechanical strength are improved, but water absorption increases leading to film swelling and delamination
Solution Approach 1:
The invention extracts and removes the harmful polyanion component from the conductive polymer system. By using intrinsically conductive polymers with self-doping groups directly incorporated into the polymer backbone, the patent eliminates the need for external polyanions that cause water absorption and swelling, while maintaining electrical conductivity and mechanical integrity
Solution Approach 2:
The invention changes the chemical structure parameters of the conductive polymer by incorporating self-doping groups (carboxylic acid, sulfonic acid, phosphonic acid, or their anhydrides) directly into the polymer backbone. This structural modification enables the polymer to maintain conductivity and adhesion properties without requiring external polyanions, thereby preventing water absorption issues
2Ease of manufacture
If the capacitor is subjected to high temperatures during soldering, then assembly is completed, but mechanical weakening occurs at interfaces due to CTE mismatches causing delamination and increased ESR
Solution Approach 1:
The invention addresses thermal expansion mismatches by using self-doped conductive polymers with enhanced crosslinking that can accommodate thermal stress. The crosslinked network structure provides mechanical robustness that resists the stresses generated during high-temperature soldering processes, preventing delamination and maintaining interface integrity
Solution Approach 2:
The invention creates a composite structure by crosslinking the self-doped conductive polymer with appropriate crosslinking agents. This composite approach combines the electrical conductivity of the conductive polymer with the mechanical strength and thermal stability of the crosslinked network, resulting in a material that can withstand soldering temperatures without delamination
3Reliability
If crosslinking is increased to improve structural integrity and reduce ESR, then adhesion and ESR stability are improved, but water resistance may be compromised
Solution Approach 1:
The invention changes the chemical composition parameters by using self-doped polymers with acidic functional groups that provide both crosslinking sites and inherent water resistance. The crosslinking is achieved through reactions of these functional groups with appropriate crosslinking agents, creating a network that maintains water resistance while providing structural integrity and low 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
The dual crosslinker system achieves lower ESR and improved ESR stability, even under high-temperature conditions, by increasing crosslinking sites and structural integrity, while maintaining water resistance.
Implementation Method 1
a dual crosslinker system including the combination of two crosslinking agents, an organofunctional silane and an organic compound with at least two functional groups selected from the group consisting of epoxy and carboxylic acid
Implementation Method 2
Polyanions readily absorb water during the capacitor processing steps (for example, dipping coating cycles) or moisture from the environment, and resulted in swelling of the conductive polymer film
Data Source
AI summary
A capacitor with improved electronic properties is described. The capacitor has an anode, a dielectric on said anode and a cathode on the dielectric. The cathode has a conductive polymer defined as —(CR1R2CR3R4—)x— wherein at least one of R1, R2, R3 or R4 comprises a group selected from thiophene, pyrrole or aniline with the proviso that none of R1, R2, R3 or R4 contain —SOOH or COOH; a organofunctional silane; and an organic compound with at least two functional groups selected from the group consisting of carboxylic acid and epoxy.