Solid Electrolytic Capacitor With Dual Conductive Polymer Layers
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Solution Overview
Problem
Solid electrolytic capacitors using conductive polymers face challenges in maintaining high capacitance and low ESR characteristics due to the removal of water-soluble self-doping type conductive polymers during the formation of the second conductive polymer layer, leading to reduced capacity and increased ESR.
Innovation Solution
A solid electrolytic capacitor design featuring a first conductive polymer layer with specific structural units, such as those represented by formulas (1) and (2), which are hydrophobic and resistant to removal, allowing for better impregnation and forming a second conductive polymer layer with improved conductivity and heat resistance, enhancing capacitance and ESR characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a water-soluble self-doping type conductive polymer is used as the first layer to easily enter etching pits, then the conductive polymer can be formed in deep parts of etching pits, but the water-soluble conductive polymer is removed when the second layer is coated, causing reduced capacitance and increased ESR
Solution Approach 1:
The invention changes the chemical parameters of the first conductive polymer by specifying it as a self-doping type polymer with particular structural formulas (1) and (2), which contain hydrophobic groups. This parameter change makes the polymer water-resistant while maintaining its ability to enter etching pits, thereby preventing removal during second layer formation and preserving capacitance and ESR characteristics.
Solution Approach 2:
The invention creates a composite structure where the first conductive polymer layer (with specific self-doping polymer formulas) is combined with a second conductive polymer layer. The first layer serves as a stable, water-resistant foundation that prevents polymer removal, while the second layer provides additional conductivity, achieving both ease of formation and reliable electrical characteristics.
2Reliability
If a conductive polymer with high conductivity is coated to compensate for capacitance decrease, then the ESR characteristic is improved, but the water-soluble self-doping type conductive polymer is removed causing capacity reduction
Solution Approach 1:
The invention performs preliminary action by forming a stable, water-resistant first conductive polymer layer with specific self-doping polymer structures before applying the second high-conductivity layer. This preliminary layer acts as a protective foundation that prevents polymer removal, ensuring that the capacitance is preserved while the second layer provides the desired low ESR characteristic.
3Volume of moving object
If the entire surface of etching pits is thinly coated with water-soluble self-doping type conductive polymer, then the conductive polymer can enter deep parts of etching pits, but part of the polymer is removed when the second layer is coated
Solution Approach 1:
The invention changes the hydrophobicity parameter of the first conductive polymer by specifying it as a self-doping type polymer with structural formulas (1) and (2) containing hydrophobic groups. This parameter change makes the polymer water-resistant, enabling it to be impregnated into deep etching pits while preventing removal during subsequent water-based processing steps.
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 proposed solution results in solid electrolytic capacitors with excellent capacitance and ESR characteristics, as the first conductive polymer's hydrophobic nature prevents its removal during the formation of the second layer, ensuring effective impregnation and improved performance.
Implementation Method 1
the first conductive polymer is mainly composed of a monoanion as a dopant and has a small amount of free sulfonic acid and high hydrophobicity, so that it is difficult to be removed when forming the second conductive polymer layer
Implementation Method 2
the first conductive polymer has a small amount of free sulfonic acid and high hydrophobicity, so that it is difficult to be removed when forming the second conductive polymer layer
Implementation Method 3
the dielectric is formed on a surface of the anode body
Data Source
Figure 1
AI summary
A solid electrolytic capacitor comprising an anode body having pores, a dielectric, a first conductive polymer layer and a second conductive polymer layer is provided. The dielectric is formed on a surface of the anode body. The first conductive polymer layer includes a first conductive polymer having at least one of structural units represented by the following formula (1) and the following formula (2) and is formed on the dielectric. In the formulas (1) and (2), R1 is an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alkylene oxide group having 1 to 12 carbon atoms, an aromatic group, or a heterocyclic group, each of which optionally has a substituent, A- is a monoanion derived from a dopant and n is 2 or more and 300 or less. The second conductive polymer layer includes a second conductive polymer different from the first conductive polymer and is formed on the first conductive polymer layer.