Anode Wire Connection in Solid Electrolytic Capacitors
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Solution Overview
Problem
The challenge is to establish a strong and reliable connection between high charge density anode powders and anode wires in solid electrolytic capacitors, particularly when using deoxygenation sintering, as existing methods result in inadequate bonding and reduced capacitance due to excessive sintering or oxygen oversaturation.
Innovation Solution
A method involving dual-density pressing of anode powders, where a high pressure region distorts the anode wire to form a strong bond, allowing for the use of high CV/g powders without degrading the charge capacity, and enabling deoxygenation sintering without the typical bonding issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the anode wire is inserted into high charge density powder and pressed during the pressing operation, then the connection is formed, but the bond between the anode wire and powder particles is inadequate
Solution Approach 1:
The patent applies localized high pressure during pressing to create a high density region around the anode wire, fundamentally changing the density parameter in the connection zone. This localized parameter change creates sufficient mechanical interlocking and bonding strength between the wire and high charge density powder particles, resolving the inadequate bond issue while preserving the overall high charge density of the anode.
2Strength
If sintering temperature is increased to improve bond strength, then the wire to anode mechanical strength improves, but the surface area of the anode metal decreases thus reducing CV/g and capacitance
Solution Approach 1:
The patent performs preliminary localized densification around the anode wire during the pressing operation, creating a high density region that provides adequate mechanical bond strength before sintering. This preliminary action eliminates the need for excessive sintering temperatures, thereby preserving the anode metal surface area and maintaining high CV/g and capacitance values.
Solution Approach 2:
The patent creates a localized high density region specifically around the anode wire connection zone, while the rest of the anode maintains optimal porosity and surface area. This local quality differentiation allows sufficient bond strength at the connection point without compromising the overall surface area needed for high capacitance.
3Quantity of substance
If deoxygenation sintering is utilized to process high charge powders, then the charge density increases, but the bond between anode and anode wire erodes leading to complete dissociation
Solution Approach 1:
The patent performs preliminary localized densification around the anode wire during pressing, creating a high density region that establishes a strong mechanical bond before deoxygenation sintering. This preliminary action prevents the bond erosion that typically occurs during deoxygenation, allowing the full charge density benefits to be realized without dissociation.
Solution Approach 2:
The patent fundamentally changes the density parameter in the connection zone through localized high pressure, creating a high density region that is resistant to the erosive effects of deoxygenation sintering. This parameter change in the connection zone protects the bond while allowing the bulk material to achieve high charge density through deoxygenation.
4Strength
If welding is used to attach the anode wire to the anode, then the connection strength improves, but double sintering is required and oxygen oversaturation occurs leading to crystalline oxide precipitation
Solution Approach 1:
The patent merges the wire attachment and anode formation operations into a single pressing step, where the anode wire is inserted and secured in the powder during pressing. This merging eliminates the need for separate welding and double sintering operations, reducing process complexity while achieving adequate connection strength through localized high density.
Solution Approach 2:
The patent changes the density parameter locally around the anode wire during pressing, creating a high density region that provides sufficient mechanical bond strength without requiring welding or multiple sintering steps. This parameter change enables single-step processing while maintaining strong connections.
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 the mechanical strength of the anode wire-powder connection, preserves the high internal surface area, and allows for the use of high charge density powders with increased volumetric efficiency and reduced wire length, leading to improved pull strength and capacitance without the need for additional sintering steps.
Implementation Method 1
pressing a second portion of the anode powder with the anode wire in the second portion to form a high density region with a second density wherein the pressing of the second portion is sufficient to distort the anode wire in the second portion
Implementation Method 2
pressing a portion of the anode powder to form a bulk region having a first density; and pressing a second portion of the anode powder with the anode wire in the second portion to form a high density region with a second density
Data Source
AI summary
An improved capacitor is provided wherein the capacitor has an improved bond between the anode and anode wire. The anode comprises a pressed anode powder comprising a first density region and a second density region wherein the second density region has a higher density than the first density region. An anode wire extends into the second density region wherein the anode wire in the second density region is distorted by compression. This allows for better utilization of the metal powder surface area by allowing a lower bulk press density and lower sinter temperature while still achieving the necessary wire pull strength. In addition, this invention when utilized with deoxidation steps, results in sufficient wire pull strengths not possible otherwise.