Solid Electrolytic Capacitor Thermal Isolation for Leakage Control
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Solution Overview
Problem
Conventional solid electrolytic capacitors face challenges in size reduction due to increased leakage current caused by welding heat affecting the porous sintered body, which is exacerbated by shorter anode wires.
Innovation Solution
A solid electrolytic capacitor design featuring a porous sintered body with an anode wire partially inserted, a dielectric layer, and a cathode portion, supported by an anode and cathode terminal structure made from a single electrically conductive base member, with an electrically conductive covering layer connecting the anode wire to the terminal without direct welding, thus minimizing thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a shorter anode wire is used to downsize the solid electrolytic capacitor, then the capacitor size is reduced, but the welding heat affects the sintered body more severely, causing increased leakage current
Solution Approach 1:
The patent introduces a heat-resistant coating layer on the anode wire and a heat-resistant structure around the welding portion as intermediary elements. These intermediaries act as thermal barriers between the welding heat source and the sintered body, allowing short anode wires to be used for miniaturization while preventing heat conduction to the sintered body, thus maintaining low leakage current
Solution Approach 2:
The patent converts the harmful welding heat into a beneficial process by controlling and localizing it. Through precise welding parameter control and heat-resistant structures, the welding heat is confined to the welding portion only, transforming what would be harmful thermal conduction into a localized beneficial bonding process that does not affect the sintered body
2Length of moving object
If the anode wire protruding part is made shorter for compactness, then the capacitor becomes more compact, but the welding portion comes closer to the sintered body, increasing thermal impact
Solution Approach 1:
The heat-resistant coating layer on the anode wire serves as a thermal intermediary that blocks heat conduction from the welding portion to the sintered body. This allows the anode wire to be positioned close to the sintered body for compactness while the coating layer maintains thermal isolation, preventing temperature increase in the sintered body
Solution Approach 2:
The patent applies heat-resistant properties locally at critical positions (coating layer on anode wire, heat-resistant structure around welding portion) rather than throughout the entire capacitor. This localized application of heat resistance enables compact design with short anode wires while maintaining thermal management only where needed, preventing excessive temperature at the sintered body
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 design allows for size reduction while suppressing leakage current increases, maintaining effective frequency characteristics and impedance performance.
Implementation Method 1
a dielectric layer covering the porous sintered body
Data Source
AI summary
A solid electrolytic capacitor includes a capacitor element, an anode terminal, a cathode terminal, and a sealing resin covering the capacitor element. The anode terminal includes a support portion for supporting the capacitor element, and an anode standing portion formed upright relative to the support portion. The capacitor element includes an anode wire projecting from a porous sintered body. The anode wire is placed on the upper end face of the anode standing portion. The anode wire and the anode standing portion have parts that are exposed from the sealing resin and covered by an electrically conductive anode terminal covering layer for ensuring electrical connection between the anode wire and the anode terminal.