Solid Electrolytic Capacitor Dielectric Layer Formation
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Solution Overview
Problem
Solid electrolytic capacitors with large surface areas, required for small-sized electronic devices, face reliability issues due to deterioration in dielectric tangent performance under high heat load tests.
Innovation Solution
A production method for solid electrolytic capacitors involving chemical formation of a dielectric layer using a dopant in an electrolytic solution, where the dopant is also used in the semiconductor layer, specifically electron-donating compounds like sulfonic acids or boron compounds, to enhance the conductivity and reliability of the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the surface area of the electric conductor is increased to achieve large capacitance, then the capacitance of the capacitor is improved, but the dielectric tangent performance deteriorates under high heat load test
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the electrolytic solution during dielectric layer formation. Specifically, it controls the concentration ratio of phosphoric acid to quaternary ammonium salt (within 5:95 to 45:55 mass%) and the concentration of quaternary ammonium salt (0.01-10 mass%). These parameter adjustments optimize the dielectric layer structure to maintain low dielectric tangent even when the conductor surface area is increased for high capacitance applications.
Solution Approach 2:
The patent creates a composite dielectric layer structure by incorporating both phosphoric acid and quaternary ammonium salt in specific proportions. This composite approach allows the dielectric layer to simultaneously achieve high breakdown voltage resistance (from phosphoric acid) and low dielectric tangent (from quaternary ammonium salt), resolving the reliability issue that arises when scaling up capacitor surface area for larger capacitance.
2Ease of manufacture
If chemical formation is performed in an electrolytic solution without a dopant, then the manufacturing process is simplified, but the reliability of the capacitor deteriorates under high heat load test
Solution Approach 1:
The patent makes the electrolytic solution multi-functional by having the electrolyte serve both as the chemical formation medium and as a dopant source. The quaternary ammonium salt in the electrolytic solution simultaneously acts as an electrolyte for chemical formation and as a dopant that improves capacitor reliability, eliminating the need for separate doping processes while enhancing performance.
Solution Approach 2:
The patent changes the chemical parameters of the electrolytic solution by incorporating quaternary ammonium salt at concentrations of 0.01-10 mass% alongside phosphoric acid. This parameter modification allows the solution to provide both the chemical formation function and the doping function, simplifying the manufacturing process while improving capacitor reliability under high heat load conditions.
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 produces high-capacitance solid electrolytic capacitors with improved reliability, as evidenced by reduced equivalent series resistance (ESR) and stability during high heat load tests.
Implementation Method 1
The dielectric layer is formed by an electrochemical method called chemical formation. An example of the forming process is a method where an electrically conducting layer is dipped in an electrolytic solution containing a mineral acid (e.g., phosphoric acid, sulfuric acid) or a salt thereof, or an organic acid (e.g., acetic acid, adipic acid, benzoic acid) or a salt thereof dissolved therein and a predetermined voltage is applied between the electric conductor serving as an anode and a cathode separately provided in the electrolytic solution. A part of the electrolyte used for the chemical formation is incorporated into the dielectric layer.
Implementation Method 2
when a dielectric layer of a solid electrolytic capacitor using a semiconductor layer comprising at least an electrically conducting polymer is formed by chemical formation in an electrolytic solution containing a dopant, a solid electrolytic capacitor exhibiting high reliability can be obtained
Data Source
AI summary
The invention produces a solid electrolytic capacitor using a solid electrolytic capacitor element by a method comprising forming a dielectric layer on the surface of an electric conductor, forming a semiconductor layer containing electrically conducting polymer on the dielectric layer and forming an electrode layer thereon, wherein the dielectric layer is formed by chemical formation in an electrolytic solution containing a dopant.