Electrolytic Capacitor Folded Lead Tab Rivet Connection
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Solution Overview
Problem
Aluminium electrolytic capacitors experience contact failures due to the formation of an oxide layer on the surface of components in the connection part, caused by residual electrolyte solution entering the gaps between the rivet, washer, and lead tab, leading to poor electrical contact over time.
Innovation Solution
The electrolytic capacitor design features a lead tab with folded sections and strategically placed washers to minimize gaps and prevent electrolyte ingress, ensuring the rivet, washer, and lead tab maintain good electrical contact by increasing the effective contact area through a 'tab-flower' configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cold welding (riveting) is used to connect the lead tab with the cover disc to save manufacturing costs, then manufacturing cost is reduced, but gaps are formed among the rivet, washer and lead tab which allow electrolyte ingress and oxide layer formation
Solution Approach 1:
The lead tab is pre-formed with a folded configuration creating multiple openings before assembly. This preliminary shaping allows the rivet to pass through multiple layers and create overlapping joints that prevent electrolyte ingress before the riveting process occurs, addressing the reliability issue while maintaining the cold welding manufacturing method
Solution Approach 2:
The lead tab is folded from a flat configuration into a three-dimensional structure with multiple layers stacked vertically. This dimensional transformation creates overlapping contact areas and eliminates gaps by distributing the connection across multiple planes, preventing electrolyte penetration while using the same riveting process
2Strength
If washers are provided between the cover disc and lead tab to fix the connection, then mechanical strength is improved, but gaps remain among the components allowing electrolyte to enter and cause oxidation
Solution Approach 1:
The lead tab is divided into multiple sections with openings distributed along its length. Each section creates a separate contact point with the rivet, segmenting the connection into multiple overlapping joints rather than a single gap-prone interface, thereby maintaining mechanical strength while eliminating continuous gaps
Solution Approach 2:
The lead tab sections are folded and nested within each other, creating a compact multi-layer structure. The rivet passes through all nested layers, creating overlapping connections where each layer protects the others from electrolyte ingress, maintaining both mechanical strength and electrical reliability
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 effectively prevents the formation of an oxide layer, thereby reducing contact failures and ensuring reliable electrical connections throughout the lifespan of the capacitor.
Implementation Method 1
The rivet is configured such that the first head of the rivet fixes the lead tab to the covering element at the inner surface of the covering element
Implementation Method 2
The lead tab is folded such that the first opening and the second opening of the lead tab are arranged above each other. The rivet is arranged in the first and the second opening of the lead tab and in an opening of the upper washer
Implementation Method 3
The connection element comprises an upper washer, wherein the upper washer is arranged between the first head of the rivet and the lead tab
Data Source
AI summary
In an embodiment an electrolytic capacitor includes a covering element configured to close an opening of a can comprising a capacitor element. A connection element comprises a lead tab for applying an electrical signal to the capacitor element and a rivet having a first head to fix the lead tab to the covering element. The connection element includes an upper washer arranged between the first head of the rivet and the lead tab. The lead tab has a first section having a first opening and a second section having a second opening. The lead tab is folded such that the first opening and the second opening of the lead tab are arranged above each other. The rivet is arranged in the first and second openings of the lead tab and in an opening of the upper washer.