Solid Electrolytic Capacitor Recessed Cathode Terminal Bonding
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Solution Overview
Problem
The existing solid electrolytic capacitors with valve metal substrates face challenges in achieving high bond strength between the capacitor element and the cathode terminal, leading to potential detachment during resin sealing, which affects electric characteristics.
Innovation Solution
A solid electrolytic capacitor design featuring a valve metal substrate with a linear shape and a recessed cathode terminal, where the cathode layer is connected to the inner wall surface of the recessed portion, enhancing the bonding area and using a metal plate cathode terminal to reduce parasitic components and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a planar cathode terminal is used to connect to the cathode layer, then the device complexity is reduced, but the bond strength between the capacitor element and cathode terminal becomes insufficient
Solution Approach 1:
The cathode terminal transitions from a planar two-dimensional structure to a three-dimensional structure with a recessed portion. This dimensional change increases the contact surface area between the cathode terminal and cathode layer, thereby enhancing bond strength without significantly increasing device complexity.
Solution Approach 2:
The cathode layer is inserted into and nested within the recessed portion of the cathode terminal. This nesting arrangement maximizes the bonding interface between the two components, creating a stronger mechanical and electrical connection while maintaining compact overall dimensions.
2Strength
If a large amount of conductive adhesive is used to increase bond strength, then the bond strength between capacitor element and cathode terminal improves, but the conductive adhesive becomes more likely to leak from the sealing material
Solution Approach 1:
By changing the cathode terminal structure to include a recessed portion, the bonding area is expanded in three dimensions. This allows sufficient bond strength to be achieved with a controlled amount of conductive adhesive, preventing overflow and leakage while maintaining strong adhesion between components.
3Strength
If the contact area between capacitor element and cathode terminal is increased, then the bond strength improves, but the manufacturing precision requirements increase
Solution Approach 1:
The recessed portion of the cathode terminal creates a localized bonding zone where the cathode layer is inserted. This localized structure concentrates the bonding area in a specific region, making alignment easier and reducing overall manufacturing precision requirements compared to distributing bonding across a larger surface area.
Data Source
AI summary
A solid electrolytic capacitor that includes at least one capacitor element having a linear-shaped valve metal substrate that extends in an axial direction and includes a porous portion on a surface of a core portion, a dielectric layer on a surface of the porous portion, and a cathode layer on the dielectric layer; a cathode terminal including a recessed portion having an inner wall surface extending in the axial direction, the capacitor element is disposed in the recessed portion, and the cathode layer is electrically connected to the inner wall surface; an anode terminal electrically connected to the core portion of the capacitor element; and a sealing material covering the capacitor element.