Solid Electrolytic Capacitor Separation Structure Against Air Infiltration
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Solution Overview
Problem
Solid electrolytic capacitors face a reduction in capacitance due to air entering through the porous anode foil, which deteriorates the conductive polymer in the solid electrolyte layer, especially under high-temperature conditions, leading to increased equivalent series resistance (ESR) and dielectric loss tangent (tan δ).
Innovation Solution
The capacitors incorporate a separation section between the anode and cathode sections with insulating materials to prevent air entry, where the porous part is compressed or removed to form grooves, and insulating materials are applied to suppress air infiltration, ensuring the solid electrolyte layer covers these regions to enhance heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If air enters through the porous part of the anode foil, then the capacitor element structure is simple and easy to manufacture, but the conductive polymer in the solid electrolyte layer deteriorates under high temperature, reducing capacitance
Solution Approach 1:
The anode foil is divided into three distinct sections: an anode section, a separation section, and a cathode formation section. The separation section acts as a barrier to prevent air from reaching the solid electrolyte layer, while the anode and cathode sections maintain their respective functions. This segmentation resolves the contradiction by introducing a protective barrier without compromising the overall manufacturing simplicity.
Solution Approach 2:
An insulating material is introduced as an intermediary substance in the separation section of the anode foil. This insulating material serves as a mediator that blocks air penetration while allowing the capacitor to maintain its basic structure. The insulating material prevents direct contact between air and the solid electrolyte layer, thereby protecting the conductive polymer from deterioration.
2Reliability
If insulating materials are added to the separation section to prevent air entry, then heat resistance and capacitance stability improve, but the device complexity increases
Solution Approach 1:
The insulating material is applied locally only in the separation section of the anode foil, rather than throughout the entire capacitor structure. This localized application provides the necessary protection against air infiltration and heat damage while minimizing the increase in device complexity. The insulating material is strategically placed where it is most needed—to block air entry—without adding unnecessary complexity to other parts of the capacitor.
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 effectively reduces the degradation of the conductive polymer, maintaining capacitance and reducing ESR and tan δ even under high-temperature exposure, thereby improving the heat resistance and performance of the solid electrolytic capacitors.
Implementation Method 1
air may enter through the porous part of the anode foil connected to the electrode terminal
Implementation Method 2
insulating materials are applied to suppress air infiltration
Data Source
AI summary
A solid electrolytic capacitor includes a capacitor element. The capacitor element includes an anode foil including a base material part and a porous part disposed on a surface of the base material part, a dielectric layer disposed on at least a part of a surface of the anode foil, a solid electrolyte layer covering at least a part of the dielectric layer, and a cathode lead-out layer covering at least a part of the solid electrolyte layer. The anode foil includes an anode section on which the solid electrolyte layer is not disposed, a cathode formation section on which the solid electrolyte layer is disposed, and a separation section located between the anode section and the cathode formation section. A first insulating material is disposed on a surface of the porous part in the separation section. And at least a part of a region of the porous part that is covered with the first insulating material includes a second insulating material.