Aluminum Wire Termination Using Conductive Foil Mediator
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Solution Overview
Problem
Aluminum conductors in automotive cables are susceptible to oxidation and galvanic corrosion when terminated with contact elements made of different materials, leading to conductivity issues and mechanical weaknesses, especially at low temperatures.
Innovation Solution
A method involving the exposure of a conductor portion, joining a conductive foil layer of a different material to the conductor, and securing a contact element to enhance conductivity and prevent corrosion, using techniques like welding and crimping with optional solder reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a contact element is directly crimped to the bare end of an aluminum conductor, then the termination process is simple, but the aluminum conductor is susceptible to oxidation and galvanic corrosion which inhibits conductivity
Solution Approach 1:
A conductive foil layer is introduced as an intermediary between the aluminum conductor and the contact element. This foil layer prevents direct contact between dissimilar metals, eliminating galvanic corrosion while maintaining electrical conductivity. The foil serves as a protective barrier that resolves the contradiction between simple termination and reliable conductivity.
Solution Approach 2:
The termination structure becomes a composite assembly consisting of the aluminum conductor, conductive foil layer, and contact element. This multi-material construction combines the advantages of each material: the aluminum provides lightweight conductivity, the foil provides corrosion protection, and the contact element provides mechanical connection, thereby improving overall reliability without significantly complicating the manufacturing process.
2Device complexity
If a contact element is directly secured to the aluminum conductor, then the structure is simple, but galvanic corrosion causes aluminum dissolution which adversely affects conductivity
Solution Approach 1:
The conductive foil layer acts as a mediator that physically separates the aluminum conductor from the contact element, preventing the electrochemical reaction that causes galvanic corrosion. This intermediary layer eliminates aluminum dissolution while maintaining electrical continuity, resolving the contradiction between structural simplicity and corrosion prevention.
3Weight of moving object
If aluminum conductor is used for weight reduction, then the cable weight decreases, but the aluminum conductor is weaker and easier to pull out of the contact element
Solution Approach 1:
The conductive foil layer reinforces the aluminum conductor at the termination point, creating a composite structure that combines the lightweight properties of aluminum with the higher strength of the foil material. This allows the cable to maintain reduced overall weight while gaining localized strength at the critical connection point, preventing pull-out failure.
4Adaptability or versatility
If aluminum conductor is terminated at low temperatures, then the cable can operate in cold environments, but the aluminum conductor exhibits mechanical creep which results in undesirable impedances
Solution Approach 1:
The conductive foil layer forms a composite termination structure with the aluminum conductor that resists mechanical creep at low temperatures. The foil material provides structural stability that prevents deformation and maintains consistent electrical impedance, enabling reliable operation across a wide temperature range without sacrificing impedance stability.
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 improves conductivity and mechanical strength at the termination point, reducing oxidation and galvanic corrosion risks, ensuring reliable connections even at low temperatures.
Implementation Method 1
joining a conductive foil layer and at least a portion of the exposed portion of the conductor together
Implementation Method 2
securing the contact element to the exposed portion of the conductor and the conductive foil layer
Implementation Method 3
The bare end of aluminum conductor, however, can be susceptible to oxidation (e.g., sapphire oxidation) which can inhibit conductivity between the bare end and the contact element
Implementation Method 4
The aluminum conductor can also be susceptible to galvanic corrosion when it is terminated to a material that is more basic than aluminum, such as brass, and when moisture is present at the interface between the conductor and the contact element
Data Source
AI summary
A method is provided for preparing a wire for installation of a terminal. The method comprises removing an insulating layer from a conductor to expose a portion of a conductor. The method further includes attaching a conductive foil layer to a portion of the exposed portion of the conductor by applying pressure to the conductive foil layer. Terminated wires are also provided.