Stepped Electrode Foil Edges to Prevent Capacitor Burr Shorts
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Solution Overview
Problem
Burr formation during the cutting of electrode foils for electrolytic capacitors can lead to reduced reliability due to potential short circuits and increased leakage current, especially in wound body configurations where burrs may break through separators.
Innovation Solution
The electrode foil design includes a metal foil with distinct regions of varying thickness, featuring a thinner second region along the edge portions and steps between these regions on both surfaces, which helps maintain insulation and distance from adjacent components, thereby preventing short circuits and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrode foil is cut to predetermined size, then manufacturing efficiency is improved, but burrs are generated that reduce reliability
Solution Approach 1:
The electrode foil is designed with different thicknesses in different regions: a first thickness in the main body and a second thickness (smaller than the first) in the second region extending along the edge portion. This local quality variation ensures that even when burrs are generated during cutting, the reduced thickness in the edge region prevents burrs from breaking through the separator, thereby maintaining reliability while allowing efficient cutting production
2Device complexity
If uniform thickness is maintained throughout electrode foil, then manufacturing simplicity is improved, but burrs can break through separator causing short circuit
Solution Approach 1:
The electrode foil incorporates a second region with reduced thickness extending linearly along the edge portion, creating local quality variation. This design specifically addresses the edge region where burrs are most likely to cause problems, while maintaining the standard thickness in the main body, thus balancing manufacturing simplicity with insulation reliability
Solution Approach 2:
The solution introduces a thickness dimension variation along the width direction of the electrode foil. By creating a thickness gradient from the main body to the edge region, the design adds a dimensional aspect to the foil structure that prevents burr penetration without requiring complex multi-layer or three-dimensional configurations
3Reliability
If edge region has reduced thickness, then burr penetration is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The reduced thickness second region is formed in advance during the foil manufacturing process, before the cutting operation. This preliminary action ensures that when burrs are generated during subsequent cutting, the protective reduced thickness structure is already in place, preventing burr penetration without requiring high precision during the cutting operation itself
Data Source
AI summary
An electrode foil for an electrolytic capacitor includes a metal foil having a first region and a second region other than the first region, in which the second region is a region extending linearly along an edge portion of the metal foil, the thickness of the second region is smaller than the thickness of the first region, and steps are provided between the first region and the second region on both surfaces of the metal foil.