Electrode Foil Etch Segmentation to Prevent Capacitor Tab Cracks
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Solution Overview
Problem
The increased fragility and reduced flexibility of electrode foil due to higher surface enlargement and chemical conversion treatments in electrolytic capacitors lead to cracks and fractures during the connection process with terminals, which are not adequately addressed by existing connection techniques.
Innovation Solution
Incorporating a plurality of interrupting parts in the etch layer of the electrode foil, particularly at the connection points, to disperse stress and prevent cracks, thereby enhancing flexibility and moldability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a surface-enlarging process with higher enlargement is applied to electrode foil to increase capacitance, then the capacitance of the electrolytic capacitor is improved, but the flexibility and extensibility of the electrode foil deteriorate due to increased fragility and hardening
Solution Approach 1:
The etch layer is divided into multiple segments by forming interrupting parts (cuts or grooves) that extend from the surface toward the core portion. This segmentation allows the etch layer to flex independently in each segment, preventing crack propagation while maintaining the overall surface area enlargement for high capacitance
Solution Approach 2:
The interrupting parts are specifically formed in the etch layer at locations where flexibility is needed (such as near connection parts or in regions subject to stress), while other areas of the etch layer maintain their full surface area for capacitance. This localized modification preserves capacitance in non-critical areas while providing flexibility where required
2Reliability
If chemical conversion treatment is applied to form dielectric oxide film on electrode foil, then the dielectric properties are improved, but the extensibility and flexibility of the electrode foil deteriorate due to the hard nature of the oxide film
Solution Approach 1:
The continuous dielectric oxide film is segmented by the interrupting parts in the etch layer beneath it. This creates discrete oxide film sections that can move independently, preventing the formation of continuous stress paths that would cause cracking while preserving the dielectric function in each segment
Solution Approach 2:
The interrupting parts are formed in the etch layer before the chemical conversion treatment. This preliminary action creates a flexible substrate structure that allows the subsequently formed oxide film to accommodate stress without cracking, as the flexibility is already built into the underlying etch layer structure
3Reliability
If stitching or cold welding is used to connect terminal to electrode foil, then the connection is achieved, but stress acts on the electrode foil causing cracks and fractures due to the hardened and fragile state of the foil
Solution Approach 1:
The interrupting parts in the etch layer serve as pre-prepared stress relief zones that cushion the impact of connection stresses from stitching or cold welding. These preemptively created flexible zones absorb and distribute the stress, preventing it from concentrating and causing cracks in the hardened electrode foil
Solution Approach 2:
The interrupting parts are strategically positioned in the etch layer beneath or near the connection areas where terminal attachment stresses are applied. This localized flexibility provision directly addresses the stress concentration problem at connection points while maintaining the integrity of the rest of the electrode foil
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 interrupting parts improve the flexibility and moldability of the electrode foil, preventing cracks and fractures, allowing for higher capacitance, improved reliability, and reduced manufacturing defects.
Implementation Method 1
a surface-enlarging process with a higher enlargement has been treated to enlarge a surface area of electrode foil
Implementation Method 2
a dielectric oxide film is formed thereover by chemical conversion treatment
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3D
AI summary
A capacitor has electrode foil (2, 60) and a terminal (tab 4) connected, an etch layer (16) being formed in the electrode foil, wherein a plurality of interrupting parts (12) are included in the etch layer, which is formed in the electrode foil, and at least in a connection part (stitching part 6) at which the terminal is connected. It makes it possible for the electrode foil of a higher capacitance to have flexibility, makes it possible to suppress cracks caused by pressing, and makes it possible to prevent cracks from spreading. In addition, such effects are expected that the electrode foil can be prevented from being damaged in a process of connecting the tab including folding the electrode foil, and pressing raised pieces of the electrode foil and the tab onto the electrode foil.