Electrolytic capacitor having an anode electrode with flat particles
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Solution Overview
Problem
The adhesion force between the electrode exposed portion of the internal electrode and the external electrode in electrolytic capacitors is weakened, particularly at the end surface on the anode side, leading to reliability issues.
Innovation Solution
An electrolytic capacitor design that includes a resin molded body with a stack of capacitor elements, where the anode external electrode has a first electrode layer in direct contact with the core of a valve-action metal substrate, and the first electrode layer consists of flat particles with an aspect ratio of 2 or more, enhancing the adhesion force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plating or thermal spraying is used to attach metal to the anode foil end surface, then the external electrode can be formed on the capacitor element, but the adhesion force between the electrode exposed portion and the metal layer is weakened at the end surface
Solution Approach 1:
The invention changes the physical and chemical parameters of the end surface by forming a roughened layer through anodization or etching, increasing surface area and creating micro-structures that enhance mechanical interlocking. It also changes the chemical composition by forming oxide layers or applying conversion coatings that improve chemical bonding between the aluminum substrate and the metal layer, thereby resolving the adhesion force weakness without compromising manufacturing feasibility.
Solution Approach 2:
The invention creates a composite structure at the end surface consisting of multiple layers: the base aluminum foil, a roughened oxide or etched layer, and the deposited metal layer. This multi-layer composite structure combines the advantages of each layer—the mechanical strength of aluminum, the adhesion-promoting properties of the roughened intermediate layer, and the electrical conductivity of the metal layer—thereby achieving both ease of manufacture and high adhesion force.
2Reliability
If the adhesion force is improved by using stronger bonding methods, then the reliability of the electrolytic capacitor improves, but the manufacturing complexity and cost increase
Solution Approach 1:
The invention replaces complex mechanical bonding methods (such as welding or mechanical fastening) with a chemical and physical surface treatment process. By using anodization or etching to create a roughened layer followed by metal deposition, the invention achieves strong adhesion through chemical bonding and mechanical interlocking at the micro-level, avoiding the need for complex external bonding mechanisms while maintaining high reliability.
Solution Approach 2:
The invention performs preliminary surface treatment (anodization or etching) on the end surface before applying the metal layer. This preliminary action prepares the surface by creating a roughened structure and chemical composition that inherently promotes adhesion, so that when the metal layer is subsequently deposited, strong bonding occurs automatically without requiring additional complex bonding steps, thereby improving reliability while controlling manufacturing complexity.
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 design achieves a high adhesion force between the internal electrode and the external electrode, improving the reliability and performance of the electrolytic capacitor.
Implementation Method 1
the adhesion force between the electrode exposed portion of the internal electrode and the external electrode
Data Source
AI summary
An electrolytic capacitor that includes: a resin molded body that includes a stack including a capacitor element and a sealing resin sealing a periphery of the stack; and an anode external electrode and a cathode external electrode on an outer surface of the resin molded body. The capacitor element includes: a valve-action metal substrate having a core and a porous portion along a surface of the core. The anode external electrode includes a first electrode layer in direct contact with the core of the valve-action metal substrate. The first electrode layer includes flat particles having an aspect ratio of 2 or more, and in a cross section, a long axis direction of the flat particles is arranged in a direction along the outer surface of the resin molded body.