Capacitor Terminal Design for High Ripple Current

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The surface contact between the terminal of a capacitor and a busbar in aluminum electrolytic capacitors is limited by the low mechanical strength and vulnerability to oxidation of high purity aluminum, which restricts ripple current ratings, especially in high volumetric power density circuit designs.

Innovation Solution

A capacitor terminal comprising two parts of different materials, where the first part is optimized for internal contact with a high purity aluminum for electrochemical compatibility and the second part, made of a material like copper or a copper alloy, provides enhanced mechanical strength and resistance to oxidation for external contact with the busbar, allowing higher ripple current capability and reduced contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high purity aluminum is used for the terminal material to ensure electrochemical compatibility with the winding element, then electrochemical compatibility is improved, but mechanical strength and resistance to oxidation deteriorate

Engineering Contradiction:

Improveelectrochemical compatibilityVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The terminal is divided into two separate parts: a first part made of high purity aluminum for internal contact with the winding element, and a second part made of a different material (such as copper or copper alloy) for external contact with the busbar. This segmentation allows each part to be optimized for its specific function, resolving the contradiction between electrochemical compatibility and mechanical strength requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials are used at different locations of the terminal structure. The first part (internal contact area) uses high purity aluminum for electrochemical compatibility, while the second part (external contact area) uses a material with superior mechanical properties and oxidation resistance. This local differentiation of material properties resolves the contradiction by providing the right material quality at the right location.

Inventive Principle:

Principle #3Local quality

2Reliability

If high purity aluminum is used for the terminal material to ensure electrochemical compatibility, then electrochemical compatibility is improved, but resistance to oxidation deteriorates

Engineering Contradiction:

Improveelectrochemical compatibilityVSAvoidoxidation vulnerability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The terminal is segmented into an internal contact part (first part) and an external contact part (second part). The first part uses high purity aluminum for electrochemical compatibility, while the second part uses a material with superior oxidation resistance for external exposure, thereby resolving the contradiction between electrochemical compatibility and oxidation resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The terminal structure implements local quality differentiation where the internal contact region uses high purity aluminum and the external contact region uses a material with enhanced oxidation resistance. This localized material selection protects the electrochemically critical internal contact while providing oxidation resistance at the externally exposed surface.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a single material is used for the terminal to simplify manufacturing, then manufacturing complexity is reduced, but performance optimization for both internal and external contacts deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcontact performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The terminal is constructed as a composite of two different materials in two distinct parts, allowing optimization of each part for its specific function (internal contact and external contact) rather than compromising with a single material. This segmentation enables superior overall performance despite increased manufacturing complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The terminal uses a composite structure combining two different materials (high purity aluminum and another material such as copper or copper alloy) to achieve properties that neither material could provide alone. This composite approach optimizes both internal electrochemical compatibility and external mechanical/contact performance.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11508527B2Capacitor, assembly comprising a capacitor and a busbar and method of manufacturing a capacitor

Publication Date: 2022.11.22 TDK ELECTRONICS AG

AI summary

A capacitor, an assembly comprising a capacitor and a busbar and a method for manufacturing a capacitor are disclosed. In an embodiment a capacitor includes a winding element and a terminal having a first part of a first material and a second part of a second material, the second material being different than the first material, wherein the first part is electrically contacted to the winding element, and wherein the second part is an external contact of the capacitor.