Solid Electrolytic Capacitor Manufacturing with Conductive Polymer and Cyclic Organic Compound
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Solution Overview
Problem
Existing methods for manufacturing solid electrolytic capacitors using conductive polymers face challenges such as high equivalent series resistance (ESR), poor heat resistance, and complex reproducibility due to the use of ferric salts in chemical oxidation polymerization, which result in non-uniformity and low conductivity.
Innovation Solution
A method involving the use of a conductive polymer formed through oxidation polymerization of thiophene derivatives with a polymer anion dopant, followed by immersion in a solution of a cyclic organic compound with a hydroxyl group to reduce ESR and enhance voltage resistance and charge discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferric salts (ferric toluenesulfonate or ferric methoxybenzene sulfonate) are used as oxidant and dopant in chemical oxidation polymerization, then the conductive polymer can be synthesized, but the initial resistance value is high and heat resistance is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the polymerization system by replacing ferric salts with ammonium persulfate as oxidant and using polystyrene sulfonic acid as dopant. This parameter change resolves the contradiction by achieving both low initial resistance and high heat resistance in the conductive polymer coating.
2Ease of manufacture
If alcohol solution of ferric toluenesulfonate or ferric methoxybenzene sulfonate is used, then the polymerization can proceed, but precipitations occur during storage and uniformity deteriorates
Solution Approach 1:
The patent replaces the unstable ferric salt alcohol solutions with ammonium persulfate and polystyrene sulfonic acid, which can be used as aqueous solutions that remain stable during storage. This substitution eliminates the precipitation problem while maintaining ease of manufacture.
3Ease of manufacture
If conductive polymer is formed directly on the element by chemical oxidation polymerization, then the coating can be formed, but the process is complicated and reproducibility is poor
Solution Approach 1:
The patent applies preliminary action by first forming a conductive polymer coating on the element, then performing a subsequent treatment with a cyclic organic compound having a hydroxyl group. This two-step process improves reproducibility by separating the coating formation from the final property optimization, making each step more controllable and repeatable.
4Adaptability or versatility
If soluble conductive polymer from polystyrene sulfonic acid, ammonium persulfate, iron salt, and ethylenedioxy thiophene is used, then the polymer can be dissolved, but the conductivity is insufficient
Solution Approach 1:
The patent changes the oxidant parameter from iron salt to ammonium persulfate, and uses polystyrene sulfonic acid as dopant. This parameter change resolves the contradiction by achieving both sufficient solubility and high conductivity in the conductive polymer, making it suitable for capacitor applications.
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 achieves a solid electrolytic capacitor with low ESR, high voltage resistance, and excellent charge discharge properties, improving the reliability and performance of the capacitors.
Implementation Method 1
a conductive polymer formed through oxidation polymerization of thiophene derivatives with a polymer anion dopant
Implementation Method 2
immersion in a solution of a cyclic organic compound with a hydroxyl group to reduce ESR and enhance voltage resistance
Data Source
AI summary
There is provided a method to provide a capacitor element including a porous body of a valve metal, and a dielectric layer of an oxide layer of the valve metal. The method includes a first sequential process, and a second sequential process. The first sequential process includes: immersing the capacitor element in a first liquid of dispersion of a conductive polymer obtained by means of oxidation polymerization of thiophene or its derivative in the presence of a dopant of a polymer anion; taking out the capacitor element from the first liquid; and drying the capacitor element. Subsequent second sequential process includes: immersing the capacitor element in a second liquid which dissolves a cyclic organic compound having at least one hydroxyl group; taking out the capacitor element from the second liquid; and drying the capacitor element.