Electrolytic Capacitor Rivet Connection Gap Sealing

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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 gaps between the rivet, upper washer, and lead tab, leading to poor electrical contact over time.

Innovation Solution

The electrolytic capacitor design incorporates a rivet with two heads, where the first head fixes the lead tab to the inner surface of the covering element and the second head fixes the external terminal to the outer surface, using upper and lower washers with specific configurations such as cavities or protrusions to minimize gaps and prevent electrolyte immersion, thereby reducing oxidation and ensuring reliable contact.

Engineering Contradictions & Design Principles

VSEngineering 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 between the rivet, upper washer, and lead tab allowing electrolyte solution to enter and cause oxide layer formation leading to contact failures

Engineering Contradiction:

Improvemanufacturing costVSAvoidelectrical contact reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The connection structure is divided into multiple components: a rivet with distinct first and second heads, an upper washer, and a lower washer. Each component performs a specific function - the first head fixes the lead tab, the second head fixes the external terminal, and the washers provide isolation and gap prevention. This segmentation allows for more reliable electrical contact while maintaining manufacturing simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rivet is designed with different heads having different functions - the first head is configured to fix the lead tab to the cover disc while the second head fixes the external terminal. The washers are positioned at specific locations (upper washer between lead tab and first head, lower washer between cover disc and lead tab) to provide local gap prevention and electrolyte isolation where most needed for electrical contact reliability.

Inventive Principle:

Principle #3Local quality

2Strength

If washers are provided between the inner surface of the covering element and the lead tab to fix the connection, then the lead tab is fixed to the cover disc, but gaps remain among the rivet, upper washer, and lead tab allowing residual electrolyte to enter and generate oxide membrane causing contact failures

Engineering Contradiction:

Improvefixing strengthVSAvoidoxide layer formation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The upper washer acts as an intermediary component between the lead tab and the first head of the rivet, while the lower washer serves as an intermediary between the cover disc and the lead tab. These washer intermediaries fill and seal gaps that would otherwise allow electrolyte solution to penetrate, thereby preventing oxide layer formation on the rivet and lead tab surfaces while maintaining the fixing strength of the connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The design converts the potential harm of gap formation into a benefit by using the washers to create a controlled sealing interface. The gaps that naturally form in riveting are transformed into sealed interfaces where the washers contact both the rivet heads and the lead tab, preventing electrolyte intrusion and oxide formation, thus turning a manufacturing characteristic into a protective feature.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 configuration effectively prevents the formation of an oxide layer, ensuring consistent electrical contact and reducing the likelihood of failures by minimizing the immersion of electrolyte and enhancing the adhesive properties between the rivet, lead tab, and washers.

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 and the second head of the rivet fixes the external terminal to the covering element at the outer surface of the covering element

Methodology Applied

Scientific EffectMechanical Fastening: Mechanical Fastener

Implementation Method 2

The connection element comprises an upper washer and a lower washer respectively having an opening to receive the rivet. The upper washer is placed between the lead tab and the first head of the rivet, and the lower washer is placed between the lead tab and the inner surface of the covering element

Methodology Applied

Scientific EffectPhysical Barrier: Physical Containment

Data Source

PatentUS11456119B2Electrolytic capacitor with improved connection part

Publication Date: 2022.09.27 TDK ELECTRONICS AG

AI summary

In an embodiment an electrolytic capacitor includes a capacitor element being housed by a can. A covering element is configured to close an opening of the can. A connection element comprises an external terminal for applying an electrical signal and a lead tab being electrically coupled to the capacitor element and to the external terminal. The connection element comprises an upper washer and a lower washer respectively having an opening to receive a rivet to fix the external terminal and the lead tab to the covering element. The upper washer is configured to either comprise a cavity to receive a head of the rivet or a protrusion or a tapered lateral surface.