NbOx Anode Ambient Pressure Forming for Capacitor Reliability
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Solution Overview
Problem
Solid electrolyte capacitors with niobium suboxide (NbOx) anodes suffer from high residual current and voltage breakdowns due to defects like microcracks in the brittle oxide ceramic, making them unsuitable for industrial use.
Innovation Solution
A process for producing solid electrolyte capacitors with an anode comprising sintered fine NbOx powder, where the anode body is formed without pressure, sintered, and then electrolytically oxidized, eliminating carbon doping and reducing carbon content to less than 25 ppm, thereby minimizing defects and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NbO is used as an anode material, then high conductivity is achieved, but high residual current and voltage breakdowns occur due to defect structures
Solution Approach 1:
The patent changes the forming pressure parameter from conventional high pressure to ambient pressure, which prevents the formation of microcracks and defect structures in the brittle NbO ceramic during shaping. This parameter change eliminates the source of high residual current while maintaining the high conductivity benefit of NbO material.
Solution Approach 2:
The patent replaces the conventional high-pressure mechanical shaping process with an ambient pressure forming process. This substitution eliminates the mechanical stress that causes microcracks in NbO, thereby reducing residual current without sacrificing the material's conductive properties.
2Reliability
If NbO is used as an anode material, then high conductivity is achieved, but voltage breakdowns occur due to microcracks in the brittle oxide ceramic
Solution Approach 1:
The patent changes the forming pressure parameter from high pressure to ambient pressure, which prevents the formation of microcracks and defect structures in the brittle NbO ceramic during shaping. This parameter change eliminates the source of high residual current while maintaining the high conductivity benefit of NbO material.
Solution Approach 2:
The patent applies ambient pressure forming as a protective measure before sintering, which prevents microcrack formation in advance. This beforehand cushioning approach avoids structural weaknesses that would lead to voltage breakdowns during capacitor operation.
3Ease of manufacture
If conventional high pressure shaping is used, then anode body is formed, but microcracks and defects are introduced in the brittle NbO ceramic
Solution Approach 1:
The patent changes the forming pressure parameter from high pressure to ambient pressure, which prevents the formation of microcracks and defect structures in the brittle NbO ceramic during shaping. This parameter change eliminates the source of high residual current while maintaining the high conductivity benefit of NbO material.
Solution Approach 2:
The patent converts the brittleness of NbO, which normally causes microcracks under high pressure, into a benefit by using ambient pressure forming. This approach exploits the material's properties to achieve defect-free structures, turning the material's weakness into a process advantage.
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 process results in capacitors with a specific residual current of less than 0.4 nA/μFV and reduced carbon content, enhancing their reliability and usability by eliminating defects and carbon-related issues.
Implementation Method 1
the anode is produced by sintering finely divided porous agglomerates of tantalum or niobium primary particles to give porous anode bodies
Implementation Method 2
The pentoxide layer on the surface of the sintered bodies (anodes) is then obtained by electrolytic oxidation (i.e., by forming/anodizing/anodically oxidizing)
Implementation Method 3
The cathode is obtained by impregnating the sponge-like structure with manganese nitrate, which is converted thermally to manganese dioxide
Data Source
AI summary
A process for producing a solid electrolyte capacitor with an anode comprising a sintered fine NbOx powder, where 0.5<x<1.7, includes forming a green anode body. The forming is essentially performed without applying a pressure. The green anode body is sintered so as to provide a sintered anode body. The sintered anode body is electrolytically oxidized so as to provide an electrolytically oxidized anode body. The electrolytically oxidized anode body is provided with a cathode so as to provide the solid electrolyte capacitor.