Solid Electrolytic Capacitor End Surface Connection Reduces ESR
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Solution Overview
Problem
Solid electrolytic capacitors with small anode lead wire and external electrode connection areas exhibit high equivalent series resistance (ESR), which is a limitation in their performance.
Innovation Solution
A solid electrolytic capacitor design featuring a columnar metal core with enlarged end surfaces and a porous layer coated with a conductive polymer, along with external terminals, increases the connection area and reduces ESR. The manufacturing method involves applying a resist film, forming a porous layer, and connecting conductive polymer layers to enhance terminal connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the connection area between anode lead wire and external electrode is kept small, then the device complexity is reduced, but the equivalent series resistance (ESR) increases
Solution Approach 1:
The patent transitions from a point-like or small-area connection to a surface-like connection by expanding the connection interface onto the end surface of the capacitor element. The external electrode is formed on the end surface to connect to the anode lead wire, creating a two-dimensional connection area that reduces resistance while maintaining structural simplicity.
Solution Approach 2:
The end surface of the capacitor element serves multiple functions: it acts as the termination point for the anode lead wire, provides a substrate for forming the external electrode, and creates the connection interface itself. This multi-functional use of the end surface reduces the need for additional connection structures.
2Reliability
If the connection area between anode lead wire and external electrode is increased, then the equivalent series resistance (ESR) is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the external electrode formation process with the anode lead wire connection structure. The external electrode is formed directly on the end surface where the anode lead wire is led out, combining the connection function and electrode function into a single integrated structure, thereby reducing overall device complexity while increasing connection area.
Solution Approach 2:
The end surface of the capacitor element is given special properties by forming the external electrode on it, creating a localized region with enhanced electrical connection characteristics. This local modification provides low-resistance connection without requiring changes to the entire device structure.
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 increased connection area between the metal core and external terminals effectively reduces the equivalent series resistance (ESR) of the solid electrolytic capacitor, improving its performance.
Implementation Method 1
the columnar metal core material having a surface partially provided with a porous layer including an oxide film
Implementation Method 2
a cathode layer including a conductive polymer, the cathode layer being electrically connected to the porous layer
Data Source
AI summary
A solid electrolytic capacitor that includes a columnar metal core material having a valve function, the metal core material having a first end surface and a second end surface opposed to the first end surface, at least one of the first end surface and the second end surface having an area larger than that of a cross section of a central portion of the metal core material in a lengthwise direction of the metal core material, and the metal core material having a surface partially provided with a porous layer including an oxide film; a cathode layer including a conductive polymer, the cathode layer being electrically connected to the porous layer, first external terminals electrically connected to the first end surface and the second end surface, respectively; and a second external terminal different in polarity from the first external terminals and electrically connected to the cathode layer.