Conductive Foam Paste for Electrical Connections
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Solution Overview
Problem
Metallic electrical connections degrade over time, leading to increased electrical resistance, heat generation, and potential melting, especially in high-intensity applications, due to variations in current density and the formation of oxide layers like alumina on aluminum conductors, resulting in inefficient and potentially hazardous connections.
Innovation Solution
An electrical connection powder and paste comprising open-cell metal foam particles and a binder, where the foam is made from alloys like iron, cobalt, or nickel coated with ductile metals like tin or indium, which reduces resistance by increasing contact points and preventing oxidation, and can be used to improve existing connections or those made of aluminum or copper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aluminum conductors are used to replace copper conductors, then cost is reduced, but electrical resistance increases due to alumina layer formation
Solution Approach 1:
The patent introduces an intermediate conductive layer between the aluminum conductor and the contact surface. This intermediate layer prevents direct oxidation of aluminum while maintaining electrical conductivity, thus resolving the contradiction between cost reduction (using aluminum) and reliability (maintaining low resistance).
Solution Approach 2:
The patent employs a composite structure consisting of an aluminum conductor core with a coating or intermetallic layer. This composite material combines the cost advantage of aluminum with the oxidation resistance and conductivity of the intermediate layer, simultaneously addressing both cost and reliability concerns.
2Ease of manufacture
If conventional metal contacts are used, then manufacturing is simple, but electrical connection degrades over time due to oxidation and increased resistance
Solution Approach 1:
The patent changes the chemical and physical parameters of the contact surface by applying specialized coatings or creating intermetallic layers. These parameter changes prevent oxidation and maintain conductivity over time, improving connection stability without significantly complicating the manufacturing process.
3Power
If high current density is concentrated on contact surfaces, then power transmission is efficient, but localized heating and degradation accelerate
Solution Approach 1:
The patent applies local quality improvements at the contact surfaces through specialized coatings or surface treatments. These local modifications distribute current density more evenly across the contact interface, reducing localized heating while maintaining overall power transmission 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
The solution significantly reduces electrical resistance and prevents degradation by ensuring homogeneous current distribution, maintaining low resistance even at high temperatures and intensities, and is cost-effective compared to using silver foam, making it suitable for high-intensity applications and improving connections in cables and other electrical engineering fields.
Implementation Method 1
the electrical connection between the conductors 12 and 14 is made by tight contact thanks to a clamping means such as a clamping bolt 16 passing through the two conductors as well as the intermediate conductive element
Implementation Method 2
This induces variations in the current density across the surfaces of the conductors. This results in electrical losses by the Joule effect and, consequently, an increase in temperature
Implementation Method 3
a disadvantage of aluminum is the formation of an alumina layer which, by increasing the resistance between the conductors, makes the connectivity difficult in the connections
Data Source
Figure 1~2
Figure 3
AI summary
An electrical connection powder comprising particles obtained by pulverising a skeleton of open cell metal foam chosen from the group consisting of iron, cobalt, nickel and the alloys of same covered with at least one coating of tin or indium or one of the alloys of same. The paste is formed from this powder dispersed in a binder such as grease. The powder or paste is particularly useful for improving the conductivity of an electrical connection consisting of a terminal (20) linked to a cable (24) consisting of a plurality of strands (30, 32, 34) by means of a crimping ring (26).