Aluminum Electrolytic Capacitor Electrode Hydration Film
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Chemical formation films in aluminum electrolytic capacitors exhibit defects due to volumetric shrinkage during dehydration, leading to weak points that allow water penetration and deterioration, particularly at voltages of 400 V or higher, which compromises their water resistance.
Innovation Solution
The method involves forming a chemical formation film with a reduced number of voids on the surface, achieved by controlling the hydration and chemical formation steps, including a hydration temperature of 78° C. to 92° C. and a chemical formation voltage of 400 V or higher, to ensure sufficient water content and effective repair of defects, with specific conditions for the mass ratio of the hydrated film and relative velocity of the chemical formation solution to improve water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical formation is performed at a voltage of 400 V or higher to achieve high withstand voltage, then the electrostatic capacitance per unit area is improved, but the chemical formation film develops many voids that reduce water resistance
Solution Approach 1:
The patent applies preliminary action by performing a hydration treatment before chemical formation to create a hydrated film on the aluminum electrode surface. This pre-formed hydrated film serves as a template that guides the subsequent chemical formation process, enabling the formation of a dense chemical formation film with fewer voids even at high voltages of 400 V or higher. The preliminary hydration step essentially prepares the surface structure in advance to prevent defect formation during the main chemical formation process.
2Object-affected harmful factors
If the chemical formation film is formed with high density to prevent water penetration, then water resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent merges two previously separate processes into a combined sequence that achieves both high density and simplicity. By combining the hydration treatment and chemical formation into an integrated two-step process where the hydrated film formation and chemical formation are sequentially performed without intermediate drying or complex preparation steps, the method achieves dense film formation with improved water resistance while maintaining manufacturing simplicity. The merging of these functions allows the process to be performed in a continuous manner.
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 approach significantly reduces the number of defects in the chemical formation film, enhancing its water resistance and preventing deterioration, thereby improving the reliability and performance of aluminum electrolytic capacitors.
Implementation Method 1
an aluminum electrode having a porous layer is immersed into a hydration treatment liquid such as hot pure water to form a hydrated film on a surface of the aluminum electrode (hydration step)
Implementation Method 2
these defects are generated due to volumetric shrinkage when the hydrated film is dehydrated to become aluminum oxide
Implementation Method 3
chemical formation is performed thereon in a chemical formation solution containing organic acid, inorganic acid, and salts thereof (chemical formation step), whereby a chemical formation film made of aluminum oxide is formed on the surface
Data Source
AI summary
An electrode for an aluminum electrolytic capacitor and a method for producing the same are provided that enable improvement of water resistance of a chemical formation film having a withstand voltage of 400 V or higher.The electrode for an aluminum electrolytic capacitor is produced by performing a hydration step of bringing the aluminum electrode into contact with a hydration treatment liquid having a temperature of 78° C. to 92° C. to form a hydrated film on the aluminum electrode and a chemical formation step of performing chemical formation at a chemical formation voltage of 400 V or higher in a chemical formation solution having a temperature of 58° C. to 78° C. to form the chemical formation film on the aluminum electrode. In this method, the amount of the hydrated film is made appropriate. In this electrode for an aluminum electrolytic capacitor, the number of voids that are exposed on a cut surface when the chemical formation film is cut is 150 voids/μm2 or smaller, and thus the water resistance thereof is high.