Solid Electrolytic Capacitor Folded Cathode Termination
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Solution Overview
Problem
Conventional solid electrolytic capacitors face issues with outgassing leading to cracks and mechanical instability, causing partial delamination of the cathode termination from the capacitor element.
Innovation Solution
A solid electrolytic capacitor design featuring an anode and cathode termination configuration with a folded region between planar portions, where the molding material encapsulates both planar and upstanding cathode termination portions, enhancing mechanical stability and reducing delamination risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrolytic capacitors use standard termination configurations, then manufacturing is simple, but outgassing causes cracks and delamination reducing mechanical stability
Solution Approach 1:
The cathode termination is divided into multiple distinct portions: a first planar portion, a second planar portion, and an upstanding portion. This segmentation allows each portion to serve specific functions - the planar portions provide stable bonding surfaces while the upstanding portion manages outgassing pathways, thereby improving mechanical stability without requiring entirely new structures
Solution Approach 2:
The cathode termination extends into the vertical dimension with an upstanding portion that rises from the planar surfaces. This three-dimensional configuration provides additional space for outgassing relief and creates a more robust mechanical structure that resists delamination, addressing the reliability issue while maintaining reasonable manufacturing complexity
2Reliability
If molding material fully encapsulates the capacitor element, then protection is improved, but cracks from outgassing cause delamination of the cathode termination
Solution Approach 1:
The upstanding portion of the cathode termination acts as an intermediary structure between the capacitor element and the molding material. It provides a dedicated pathway for outgassing to escape while maintaining the protective encapsulation, thereby mediating between the need for protection and the harmful effects of outgassing
Solution Approach 2:
By segmenting the cathode termination into multiple portions with different orientations and functions, the design creates specialized zones for handling outgassing. The upstanding portion specifically addresses gas escape while the planar portions maintain bonding integrity, reducing delamination risk while preserving protective encapsulation
3Reliability
If the cathode termination uses a simple flat structure, then manufacturing is easier, but mechanical stability is reduced due to delamination from outgassing cracks
Solution Approach 1:
The cathode termination is segmented into multiple portions that can be formed through sequential bending operations. This segmentation improves mechanical stability by creating a three-dimensional structure resistant to delamination, while the bending process remains compatible with conventional manufacturing techniques
Solution Approach 2:
The cathode termination is pre-formed with its multi-port ion structure (first planar portion, second planar portion, and upstanding portion) before final assembly. This preliminary formation of the complex structure allows for optimized mechanical stability and outgassing management while simplifying the final assembly process
Data Source
AI summary
A capacitor containing a solid electrolytic capacitor element that includes an anode, dielectric, and a cathode that includes a solid electrolyte is provided. An anode lead extends from the anode and is electrically connected to an anode termination. Likewise, a cathode termination is electrically connected to the cathode. The cathode termination contains an upstanding portion that is oriented generally perpendicular to the lower surface of the capacitor element, and first and second planar portions that are oriented generally parallel to the lower surface of the capacitor. The first and second planar portions are interconnected by a folded region so that the first portion is positioned vertically above the second portion. Thus, after encapsulating the capacitor element with a molding material, the second planar portion remains exposed for subsequent connection to an electrical component. However, due to its higher vertical position, the first planar portion can be completely encapsulated by the molding material. In addition, the upstanding portion of the cathode termination is also substantially encapsulated by the molding material. By encapsulating both planar and upstanding portions of the cathode termination with the molding material, the present inventors have discovered that the likelihood of delamination is reduced even if a portion of the molding material cracks. This improves mechanical stability and electrical performance.