Electrode Foil Etch Resist Masking for Capacitor Reliability
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Solution Overview
Problem
Conventional electrolytic capacitor anode foils face challenges such as increased brittleness and production inefficiencies due to extensive etching, leading to short circuits, burrs, and high leakage currents, which compromise the quality and reliability of capacitors in implantable medical devices like ICDs.
Innovation Solution
A method involving the application of an etch resist mask to create a non-etched frame around the electrode edges, allowing for controlled etching and reducing brittleness, while using ink-jet or screen printing for precise pattern formation, thereby minimizing particle formation and crack propagation during punching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If extensive etching is performed to increase surface area and capacitance, then capacitance is improved, but brittleness increases and particle detachment occurs
Solution Approach 1:
The patent applies different etching depths to different regions of the foil. The center region undergoes extensive etching to create high capacitance, while the peripheral region maintains minimal etching to preserve structural strength and prevent particle detachment. This local differentiation resolves the contradiction between maximizing capacitance and maintaining mechanical integrity.
2Quantity of substance
If tunnel density is increased to enlarge surface area, then capacitance is improved, but foil brittleness increases causing cracks during punching
Solution Approach 1:
The patent creates a gradient in tunnel density across the foil, with high tunnel density in the center region for maximum capacitance and low tunnel density at the periphery for mechanical strength. This spatial variation in etching intensity prevents crack formation during punching while maintaining high overall capacitance.
3Area of moving object
If more foil material is removed during etching and widening, then surface area increases, but particle formation increases leading to short circuits
Solution Approach 1:
The patent concentrates the material removal process in the center region where it contributes to capacitance, while preserving the peripheral region with minimal material removal. This prevents particle formation at the edges that could cause short circuits, while still achieving the desired surface area increase for high capacitance in the functional region.
4Quantity of substance
If conventional etching processes are used to maximize capacitance, then surface area increases, but production efficiency decreases due to manual mask alignment
Solution Approach 1:
The patent employs a self-aligning mask system that automatically positions itself during the etching process, eliminating the need for manual alignment by operators. This maintains the capability for differentiated etching patterns while significantly improving production efficiency and reducing labor requirements.
5Quantity of substance
If etching is performed to increase capacitance, then energy storage capacity is improved, but leakage current increases due to edge effects
Solution Approach 1:
The patent minimizes etching at the peripheral regions where edge effects occur, thereby reducing the sources of leakage current. The center region maintains extensive etching for high energy storage capacity. This spatial differentiation resolves the contradiction between maximizing energy storage and minimizing leakage current.
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
This approach enhances capacitance while reducing brittleness and particle detachment, improving capacitor quality by minimizing short circuits and leakage currents, and enabling more efficient production with reduced material waste and operator involvement.
Implementation Method 1
forming an intermittent etch resist pattern on a surface of a substrate; etching a first area of the surface substantially enclosed by the intermittent etch resist pattern and a second area in intervals between the intermittent etch resist pattern
Implementation Method 2
The etch initiation and hence the gain or capacitance of the foil is the result of several variables, such as foil cubicity, thermal oxide on the foil, and the electrochemical reaction. As tunnel density (i.e., the number of tunnels per square centimeter) is increased, a corresponding enlargement of the overall surface area will occur.
Implementation Method 3
an oxide layer on the anode foil functions as the dielectric
Implementation Method 4
The electrolyte impregnated in the separator functions as the cathode in continuity with the cathode foil
Data Source
AI summary
Electrode foils suitable for use in electrolytic capacitors, including those having multiple configurations, have improved strength, reduced brittleness, and increased capacitance compared to conventional anode foils for electrolytic capacitors. Exemplary methods of manufacturing an anode foil suitable for use in an electrolytic capacitor include forming a pattern of etch resist on a surface of a substrate; etching a first area of the surface substantially enclosed by the pattern and a second area in intervals between the pattern to form tunnels in first and second areas of the surface; and removing the resist material revealing a non-etched frame. The resist material may be deposited, for example, by ink-jet printing, stamping or screen printing. Additionally, an etch resist pattern may be used to form strength lines on the substrate surface.