Solid Electrolytic Capacitor Intermediate Layer Adhesion
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Solution Overview
Problem
In solid electrolytic capacitors, the increased hardness of composite metal nitride hard coating films leads to poor adhesion with the cathode, causing separation and increased leakage current during the winding process, and the existing solutions do not adequately address these issues.
Innovation Solution
Incorporating an intermediate layer between the cathode and the hard coating film, composed of a substance different from the hard coating film, which improves adhesion and alleviates stress during the winding process, thereby preventing separation and leakage current increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a hard coating film made of composite metal nitride is formed on the cathode to increase capacity, then the capacitance increases, but the adhesion between the coating film and cathode deteriorates due to stress during winding
Solution Approach 1:
The hard coating film is divided into multiple layers: an inner layer made of aluminum nitride or titanium nitride that provides good adhesion to the cathode, and an outer layer made of composite metal nitride that provides high capacitance. This segmentation allows each layer to perform its specific function without compromising the other.
Solution Approach 2:
The inner layer of aluminum nitride or titanium nitride acts as an intermediary between the cathode and the outer composite metal nitride layer. It provides a transition zone that maintains adhesion while allowing the outer layer to deliver high capacitance performance.
2Temperature
If the hardness of the hard coating film is increased to improve performance, then the capacitance and heat resistance improve, but the stress during winding causes separation and increased leakage current
Solution Approach 1:
The coating structure is segmented into an inner layer with lower hardness and high adhesion, and an outer layer with higher hardness and high capacitance. This segmentation allows the outer layer to provide heat resistance without causing separation, as the inner layer absorbs the winding stress.
Solution Approach 2:
Different regions of the coating film have different properties: the inner layer has properties optimized for adhesion and stress resistance, while the outer layer has properties optimized for capacitance and heat resistance. This local differentiation resolves the contradiction between hardness and adhesion.
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 intermediate layer enhances the adhesion between the cathode and the hard coating film, reducing leakage current and improving the capacitor's capacity, heat resistance, and overall performance compared to conventional capacitors.
Implementation Method 1
Incorporating an intermediate layer between the cathode and the hard coating film, composed of a substance different from the hard coating film, which improves adhesion
Implementation Method 2
the intermediate layer enhances the adhesion between the cathode and the hard coating film, reducing leakage current and improving the capacitor's capacity
Data Source
AI summary
A solid electrolytic capacitor is configured to include a wound capacitor element that has an anode (2), a cathode (3) composed of aluminum, a hard coating film (28) formed on a surface of the cathode (3), a separator (4b), and a solid electrolyte layer, and is also configured so that the solid electrolytic capacitor further includes an intermediate layer 18 formed between the cathode (3) and the hard coating film (28), the hard coating film (28) is composed of a compound of aluminum, titanium, and at least one nonmetallic element, and the intermediate layer (18) contains at least one element selected from the group of metallic elements consisting of aluminum and titanium. It is particularly preferable that the hardness of the substance that constitutes the intermediate layer (18) of the solid electrolytic capacitor be less than the hardness of the substance that constitutes the hard coating film (28).