Solid Electrolytic Capacitor with High-Melting Hydroxy Compound
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Solution Overview
Problem
Existing solid electrolytic capacitor technologies face issues with reduced withstand voltage, increased equivalent series resistance (ESR), and decreased capacitance under high-temperature conditions, particularly due to complex conductive film formation methods and low conductivity of manganese oxide layers.
Innovation Solution
A solid electrolytic capacitor with a solid electrolyte layer comprising a hydroxy compound having three or more hydroxyl groups and a melting point above 170°C, along with a conductive polymer obtained through chemical oxidative polymerization, is used, with a water content adjusted between 0.1% to 7% by mass, and a pH-adjusted solvent for improved conductivity and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conductive layer composed of manganese oxide is formed in advance on the surface of a valve metal porous body, then the electrolytic polymerization can be performed, but the method becomes more complex and the formed manganese oxide has low conductivity
Solution Approach 1:
The invention extracts and removes the manganese oxide conductive layer formation step from the conventional process. Instead of forming a conductive layer in advance, the patent directly applies conductive polymer solution to the oxidized valve metal surface, eliminating the intermediate manganese oxide layer and simplifying the overall process while achieving sufficient conductivity through the conductive polymer alone
Solution Approach 2:
The invention segments the conductive film formation process into a direct application step where conductive polymer solution is applied to the oxidized surface. This separates the oxidation step from the conductive layer formation, allowing each step to be optimized independently and reducing overall process complexity
2Reliability
If conventional solid electrolyte compositions are used, then the capacitor can be produced, but the ESR increases and heat resistance decreases under high-temperature conditions
Solution Approach 1:
The invention changes the chemical composition parameters of the solid electrolyte by incorporating specific hydroxy compounds (sorbitol, mannitol, inositol) into the conductive polymer matrix. This compositional modification enables the electrolyte to maintain low ESR and high conductivity under high-temperature conditions, improving heat resistance without complicating the manufacturing process
Solution Approach 2:
The invention creates a composite solid electrolyte material combining conductive polymer with hydroxy compounds. This composite structure leverages the conductivity of the polymer and the thermal stability of the hydroxy compounds, achieving both low ESR and high heat resistance simultaneously
3Reliability
If the solid electrolyte is formed by conventional methods, then the capacitor can be assembled, but the withstand voltage tends to fall
Solution Approach 1:
The invention optimizes the water content parameter in the solid electrolyte to a specific range (0.1-7% by mass). This parameter control is critical: sufficient water maintains high capacitance by facilitating ion conduction, while limited water prevents excessive pressure buildup that would reduce withstand voltage. The hydroxy compounds help maintain this balance by controlling moisture retention
4Reliability
If sorbitol or mannitol are used as conductivity improvers, then the conductivity can be improved, but the melting point is too low for high-temperature mounting processes
Solution Approach 1:
The invention changes the physical parameter of melting point by selecting hydroxy compounds with melting points of 170°C or higher (such as inositol at 207°C, mannitol at 166°C when combined with other compounds, or other high-melting polyols). This ensures the conductivity improver remains stable during high-temperature solder reflow processes while still providing the necessary conductivity enhancement
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 solution maintains high capacitance and low ESR while providing enhanced heat resistance and ease of production, ensuring stable performance under high-temperature conditions.
Implementation Method 1
a conductive polymer obtained through chemical oxidative polymerization
Implementation Method 2
a dielectric layer formed by oxidation of the surface of the anode
Data Source
AI summary
A solid electrolytic capacitor that is able to maintain a high capacitance and low ESR, and also exhibits a high degree of heat resistance. The solid electrolytic capacitor 10 comprises at least an anode body 11 composed of a porous material, a dielectric layer 12 formed on the surface of the anode body 11, and a cathode body 13b, wherein the solid electrolytic capacitor has a solid electrolyte layer 13a formed in contact with the dielectric layer 12, the solid electrolyte layer 13a comprises at least a hydroxy compound having three or more hydroxyl groups, and the hydroxy compound has a melting point of not less than 170°C.