Solid Electrolytic Capacitor Terminal Design for ESR Reduction
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Solution Overview
Problem
Conventional solid electrolytic capacitors face issues with product defects and low production efficiency due to strain and size constraints during terminal bending, and increased ESR caused by long lead-out distances and inadequate volume efficiency.
Innovation Solution
The design features a cathode terminal with an upper step portion connected to the cathode member, a lower step portion exposed outside the mold resin, and a side portion extending along the cathode member's side surface, eliminating the need for insulating tape and allowing for improved contact surface area, thus preventing mold resin intrusion and enhancing production efficiency and reducing ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the anode terminal and cathode terminal are bent along the circumferential surface of the mold resin portion, then the terminals are exposed out of the mold resin portion, but strain is generated making it practically difficult to perpendicularly bend the terminals, resulting in larger than standardized sizes and defective products
Solution Approach 1:
The patent applies preliminary action by pre-forming the terminal structure with sufficient bending margin built into the terminal geometry before molding. The terminal is designed with extra length and appropriate curvature radius in advance, allowing the bending operation to be performed without generating excessive strain that would compromise manufacturing precision or result in defective products.
2Ease of manufacture
If a margin for bending is required for the anode terminal and cathode terminal, then the size of the mold resin portion has to be large, but this makes it difficult to make the solid electrolytic capacitor compact and low in height, reducing volume efficiency
Solution Approach 1:
The patent applies local quality by concentrating the bending margin specifically at the terminal regions where it is actually needed for the bending operation, rather than increasing the overall size of the mold resin portion. This localized approach allows the terminals to be bent with sufficient margin while keeping the main body of the capacitor compact and maintaining volume efficiency.
3Ease of operation
If the lead-out distance from the anode lead to the exposed portion of the anode terminal and from the cathode lead-out layer to the exposed portion of the cathode terminal is increased, then the terminals can be properly formed, but the ESR of the solid electrolytic capacitor is increased
Solution Approach 1:
The patent applies parameter changes by optimizing the geometric parameters of the terminal structure, specifically the curvature radius and length of the bent portions. By carefully controlling these parameters, the terminal can be properly formed with adequate bending margin while minimizing the lead-out distance, thus maintaining low ESR and high reliability.
4Reliability
If the lower surfaces of the anode terminal and cathode terminal are protected with insulating tape to prevent mold resin penetration, then product defects are reduced, but the production process becomes more complex and production efficiency decreases
Solution Approach 1:
The patent applies the taking out principle by completely eliminating the insulating tape protection step from the production process. This is achieved by designing the terminal structure and molding process such that mold resin penetration is prevented through structural means rather than requiring additional protective materials, thereby simplifying the production process and improving productivity while maintaining product quality.
5Ease of manufacture
If a space is formed in the interface between the upper mold and lower mold to accommodate insulating tape thickness, then the insulating tape can be adhered, but the pressure of the molds to the insulating tape is not high enough, causing mold resin to leak to the adhered surface
Solution Approach 1:
The patent applies the blessing in disguise principle by converting the potential harm of mold resin leakage into a benefit through structural design. The terminal structure is designed to inherently prevent mold resin penetration without requiring insulating tape, thereby eliminating the mold resin leakage problem entirely while maintaining ease of manufacture.
Data Source
AI summary
A solid electrolytic capacitor including a capacitor element having an anode member and a cathode member, an anode terminal electrically connected with the anode member, a cathode terminal electrically connected with the cathode member, and a mold resin portion covering the capacitor element; wherein the cathode terminal has an upper step portion, a lower step portion, and a side portion, the upper step portion is connected with the cathode member, the lower step portion is exposed out of the mold resin portion, the side portion is extended along with a side surface of the cathode member from the upper step portion and is connected with the side surface, and the side portion is longer than the upper step portion, in a direction in which the cathode terminal and the anode terminal are aligned.