Etch Resist Masked Anode Frame for Laser Cutting and Leakage Reduction
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Solution Overview
Problem
Conventional electrolytic capacitor foil etching processes compromise between capacitance gain and foil strength, limiting the useable capacitance due to uniform etching which reduces the strength of the aluminum foil.
Innovation Solution
A non-uniform etching method is employed where an etch-resistant mask is applied to protect the foil perimeter from etching, allowing for increased surface area in exposed areas without significantly decreasing the overall strength of the foil, using materials like acrylic ink and specific etch electrolyte solutions to enhance capacitance while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If uniform etching is applied across the entire foil surface, then capacitance surface area is increased, but foil strength is reduced
Solution Approach 1:
The patent applies different etching treatments to different regions of the foil: the peripheral region (within 3mm of the edge) is minimally etched to preserve strength and prevent brittleness, while the central region is fully etched to maximize capacitance. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The foil is divided into two distinct zones: a peripheral unetched zone and a central etched zone. This segmentation allows the patent to achieve high capacitance in the central area while maintaining structural integrity through the unetched peripheral frame, thus resolving the strength-capacitance tradeoff.
2Quantity of substance
If etching is performed to increase capacitance, then energy density is improved, but leakage current increases
Solution Approach 1:
The unetched peripheral frame serves as a low-leakage current region that borders and contains the high-capacitance etched central region. This local quality differentiation reduces overall leakage current while preserving capacitance benefits.
3Quantity of substance
If etching is performed to increase capacitance, then energy density is improved, but foil deformation and brittleness increase
Solution Approach 1:
The foil is segmented into an unetched peripheral frame that maintains structural stability and resistance to deformation, and a central etched region that provides high capacitance. The unetched frame acts as a structural support that prevents overall foil deformation.
Solution Approach 2:
Different regions are assigned different properties: the peripheral region maintains original foil strength and flexibility, while the central region is optimized for capacitance. This local quality assignment resolves the contradiction between capacitance gain and deformation resistance.
4Quantity of substance
If etching is performed to increase capacitance, then energy density is improved, but thermal oxidation increases
Solution Approach 1:
The unetched peripheral frame creates a reduced-edge effect that minimizes thermal oxidation at the foil edges, while the central etched region maintains high capacitance. The unetched region serves as a protective boundary that reduces overall thermal oxidation.
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 method increases capacitance per unit volume of the electrolytic capacitor while maintaining foil strength, reducing thermal oxidation and leakage current, and preventing brittleness, enabling the production of high-capacity foils suitable for compact implantable cardioverter defibrillators.
Implementation Method 1
an etch-resistant mask is applied to protect the foil perimeter from etching
Implementation Method 2
surface area of the foil is increased by electrochemically removing portions of the foil to create etch tunnels
Implementation Method 3
Facilitation of laser cutting
Data Source
AI summary
The present invention is directed to a method of etching anode foil in a non-uniform manner which minimizes thermal oxidation during foil cutting. Having less oxide improves the ability to cut through aluminum anodes with lower energy rates. In aluminum foils, it has been found that a masking step before etching reduces conversion of boehmite aluminum oxide to alpha-phase corundum during laser cutting of anodes, which increases edge quality and productivity. Additionally, the non-etched anode frame allows for less surface area to form during the aging process. As a result, the leakage current is reduced by the proportion of edge to anode surface area, and the aging process will be faster, leading to higher productivity.