Contoured Anode for Heat-Resistant Clamshell Capacitor Welding
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Solution Overview
Problem
The heat generated during the welding process of clamshell capacitor casings can damage the separator in electrolytic capacitors, particularly in implantable medical devices, necessitating additional protective measures like metal weld straps and polymeric insulating rings that occupy valuable space.
Innovation Solution
The anode is contoured to create a sufficient gap distance from the weld site, preventing heat conduction and convection from damaging the separator, thus eliminating the need for weld straps and insulating rings by increasing the distance between the weld location and the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mating clamshells are used for capacitor casing, then hermetic sealing is achieved, but weld heat damages the separator requiring additional protective parts
Solution Approach 1:
The anode is segmented into a first portion and a second portion with a gap between them, allowing the separator to be positioned away from the weld site while maintaining electrical functionality through the electrolyte-filled gap
Solution Approach 2:
The electrolyte acts as an intermediary medium, allowing ionic conduction between the anode portions while the physical gap prevents thermal conduction from the weld site to the separator
2Object-affected harmful factors
If weld straps and insulating rings are added to protect separator, then heat damage is prevented, but interior space is reduced
Solution Approach 1:
The harmful function of the weld strap and insulating ring is extracted and replaced by the contoured anode structure itself, which provides thermal protection through its geometry rather than requiring separate protective components
Solution Approach 2:
The protective function previously requiring separate components (weld strap and insulating ring) is merged into the anode structure itself through contouring, eliminating additional parts while maintaining protection
3Volume of moving object
If drawn casing portion with plate cover is used, then volumetric efficiency is improved, but separator remains close to weld site requiring protection
Solution Approach 1:
The anode structure has different geometries in different regions: the contoured portions create gaps near the weld site for thermal protection, while other regions maintain compact dimensions for volumetric efficiency
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 protects the separator from heat damage during welding without occupying additional space, enhancing the volumetric efficiency and structural integrity of the capacitor for use in implantable medical devices.
Implementation Method 1
preventing heat conduction and convection from damaging the separator
Implementation Method 2
preventing heat conduction and convection from damaging the separator
Data Source
AI summary
An electrical energy storage device such as a wet tantalum electrolytic capacitor or an electrochemical cell such as a lithium/silver vanadium oxide cell is described. The enclosure comprises a drawn casing portion having a planar face wall supporting a surrounding sidewall and is shaped to nest the anode, cathode and intermediate separator components. A mating cover is a stamped planar piece of similar material having a periphery edge welded to the edge of the casing portion surrounding sidewall. In order to prevent heat generated during the welding process from damaging the separator, the anode portion adjacent to the weld site is contoured. This provides sufficient space between the weld and the separator supported on the anode at the contour so that what heat is transmitted to the separator by convection and conduction mechanism will not damage the separator.