Solid Electrolytic Capacitor Phosphonic Acid Coupling Layer
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Solution Overview
Problem
Solid electrolytic capacitors with conductive polymer layers face challenges in achieving high capacitance and low equivalent series resistance (ESR) due to inadequate adherence between inorganic dielectric layers and organic conductive polymer layers, despite using silane coupling agents for surface treatment.
Innovation Solution
A solid electrolytic capacitor design incorporating a coupling agent with phosphonic acid groups bonded via an alkyl chain, which directly reacts with the dielectric layer to form a robust coupling agent layer, enhancing adherence and electrical conductivity, and further reducing ESR by sequential formation of conductive polymer layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silane coupling agents are used for surface treatment of dielectric layers, then adherence between dielectric and conductive polymer layers is improved, but ESR reduction is not satisfactory
Solution Approach 1:
The patent introduces a coupling agent layer as an intermediary between the dielectric layer and conductive polymer layer. This coupling agent contains both inorganic coupling groups (for bonding to dielectric) and organic functional groups (for bonding to conductive polymer), serving as a mediator that bridges the inorganic-organic interface and enables effective stress and charge transfer, thereby simultaneously improving adherence and reducing ESR.
Solution Approach 2:
The coupling agent itself is a composite material with dual functionality: inorganic coupling groups (such as silane or phosphonic acid groups) that bond to the dielectric layer, and organic functional groups (such as hydroxyl, carboxyl, or amino groups) that bond to the conductive polymer. This composite structure at the interface enables simultaneous achievement of strong adherence and low ESR.
2Loss of energy
If conductive polymer layers are formed on dielectric layers, then ESR is reduced, but capacitance is not sufficiently increased
Solution Approach 1:
The coupling agent layer acts as an intermediary that enhances the interfacial contact between dielectric and conductive polymer, enabling more effective utilization of the conductive polymer's properties. This improved interface allows for better charge transfer and higher effective capacitance while maintaining low ESR.
Solution Approach 2:
The coupling agent provides localized functional groups at the interface that specifically enhance charge transfer and adhesion in the critical interfacial region. This local quality improvement at the dielectric-polymer interface enables superior electrical performance without requiring changes to the bulk materials.
3Reliability
If repeated silane coupling agent treatment is performed, then adherence is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent combines multiple functions (adhesion promotion, conductivity enhancement, and corrosion resistance) into a single coupling agent layer formation step. This merging of functions into one integrated process eliminates the need for repeated separate treatment steps, thereby simplifying the manufacturing process while achieving superior adherence.
Solution Approach 2:
The coupling agent exhibits multi-functionality: it provides adhesion promotion through chemical bonding to both dielectric and polymer, enhances electrical conductivity through organic functional groups, and offers corrosion resistance. This universality allows a single treatment step to achieve multiple objectives that previously required multiple 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 a solid electrolytic capacitor with increased capacitance and reduced ESR, improved adherence between layers, and enhanced storage stability, addressing the limitations of existing technologies.
Implementation Method 1
a first coupling agent layer made of a coupling agent containing phosphonic acid groups, the first coupling agent layer being provided on the dielectric layer
Implementation Method 2
a solid electrolyte layer is provided on the dielectric layer... a conductive polymer is used as the solid electrolyte layer to seek to reduce the equivalent series resistance (ESR)
Implementation Method 3
the surface of an anode formed of a sintered body of a valve metal, such as tantalum, niobium, titanium or aluminum, is anodized to form a dielectric layer
Data Source
AI summary
The invention aims at providing a solid electrolytic capacitor having a high capacitance and a small equivalent series resistance (ESR) and a method for manufacturing the same. A solid electrolytic capacitor includes: an anode 1 made of a valve metal or an alloy thereof; a dielectric layer 2 provided on the surface of the anode 1; a first coupling agent layer 3 made of a coupling agent having a molecular structure in which at least two phosphonic acid groups are bonded via an alkyl group, the first coupling agent layer 3 being provided on the dielectric layer; a first conductive polymer layer 4 provided on the first coupling agent layer 3; and a cathode layer 11 provided on or above the first conductive polymer layer 4.