Solid Electrolytic Capacitor Cathode Layer for Low Leakage Current
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Solution Overview
Problem
Solid electrolytic capacitors using copper particles in the metal particle-containing layer experience increased leakage current after exposure to high temperatures, leading to potential short-circuiting and increased defect rates.
Innovation Solution
Incorporating first metal particles with a silica core and a silver-containing coating layer into the cathode section, which reduces the silver content while maintaining high conductivity and minimizing ion migration to the solid electrolyte layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper particles are used in the metal particle-containing layer instead of silver particles, then manufacturing cost is reduced, but leakage current increases significantly after exposure to high temperatures
Solution Approach 1:
The invention uses a composite particle structure consisting of a copper core and a silver coating layer. This composite material combines the cost advantage of copper with the high-temperature stability of silver, resolving the contradiction between manufacturing cost and reliability after high-temperature exposure.
Solution Approach 2:
The silver coating is applied locally on the surface of copper particles rather than using pure silver throughout. This local application of silver provides the necessary high-temperature stability at the particle surface while maintaining copper as the bulk material, thus reducing overall cost while preventing leakage current increase.
2Reliability
If silver particles are used in the metal particle-containing layer, then leakage current after high-temperature exposure is minimized, but manufacturing cost increases
Solution Approach 1:
The invention replaces pure silver particles with composite particles having a copper core and silver coating. This reduces the overall silver content and manufacturing cost while maintaining the leakage current performance through the protective silver coating layer.
Solution Approach 2:
The invention uses copper as the core material which is cheaper than silver, while applying a thin silver coating that provides the necessary performance. This approach uses expensive material (silver) only where absolutely necessary for performance, minimizing cost while maintaining reliability.
3Ease of manufacture
If copper particles are used in the metal particle-containing layer, then manufacturing cost is reduced, but defect rate increases due to potential short-circuiting
Solution Approach 1:
The silver coating layer on copper particles acts as a protective barrier that prevents copper oxidation and ion migration, which are the root causes of short-circuiting and defects. This composite structure maintains low defect rates while using cost-effective copper as the core material.
Solution Approach 2:
The silver coating is applied in advance to copper particles before they are incorporated into the capacitor structure. This preliminary protective layer prevents subsequent oxidation and ion migration that would lead to short-circuits and defects during high-temperature processing and operation.
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
This approach reduces manufacturing costs, minimizes leakage current after high-temperature exposure, and enhances moisture resistance, ensuring high reliability and performance comparable to conventional silver paste layers.
Implementation Method 1
a silver-containing coating layer covering the core particle
Data Source
AI summary
A solid electrolytic capacitor element included in a solid electrolytic capacitor includes an anode body, a dielectric layer formed at a surface of the anode body, and a cathode section covering at least part of the dielectric layer. The cathode section includes a solid electrolyte layer covering at least part of the dielectric layer, and includes a metal particle-containing layer in at least part of the cathode section. Metal particles contained in the metal particle-containing layer include first metal particles containing silver. The first metal particles each include a core particle containing silica, and a silver-containing coating layer covering the core particle.