Plated Wire Terminal Structure for Corrosion-Resistant Ultrasonic Joining
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Solution Overview
Problem
The existing terminal-equipped electric wires with dissimilar metal contacts, such as aluminum and copper, are prone to corrosion when exposed to moisture, leading to unstable electrical connections and increased resistance, and current solutions like plating require multiple processing steps and are costly.
Innovation Solution
A terminal-equipped electric wire configuration featuring a terminal with a single plating layer, including a nickel or silver plating with a hard and thick insulating coating, applied to the entire surface, and an uneven shape on the connection portion to ensure reliable electrical connection by breaking the insulating coating when connected to a target member, facilitating ultrasonic joining without thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal surface is plated with aluminum-based metal to prevent corrosion, then corrosion resistance is improved, but ultrasonic joining becomes difficult due to high melting point
Solution Approach 1:
The terminal surface is divided into two functional zones: a contact portion with aluminum-based plating for corrosion resistance and electrical connection, and a non-contact portion with tin plating for ultrasonic joining. This segmentation allows each area to have optimized properties for its specific function.
Solution Approach 2:
Different plating materials are applied to different locations on the terminal surface. The contact portion receives aluminum-based plating for corrosion protection, while the joining portion receives tin plating for low-melting-point ultrasonic bonding. This local differentiation resolves the contradiction between corrosion resistance and joinability.
2Reliability
If nickel plating is applied to the contact portion to prevent corrosion, then corrosion resistance is improved, but electrical connection becomes difficult due to thick oxide film
Solution Approach 1:
Aluminum-based plating is specifically applied to the contact portion where electrical connection is required, while nickel plating is applied to the non-contact portion for corrosion protection. The aluminum-based plating provides both corrosion resistance and good electrical conductivity, avoiding the oxide film issue that would occur with nickel plating at the contact interface.
3Reliability
If multiple plating processes are applied to different portions of the terminal, then corrosion resistance and electrical connection are improved, but production cost and complexity increase
Solution Approach 1:
The terminal manufacturing process is segmented into distinct plating stages: aluminum-based plating is applied first to the contact portion, followed by tin plating on the non-contact portion. This segmented approach allows for targeted application of plating materials, reducing waste and simplifying quality control compared to uniform multi-layer plating.
Solution Approach 2:
The aluminum-based plating is applied as a preliminary layer to establish corrosion resistance and electrical connection properties before applying the tin plating layer for ultrasonic joining. This preliminary action ensures that the base functional requirements are met before adding the joining-specific coating.
4Strength
If resistance welding is used to join aluminum electric wire and terminal, then joining is achieved, but thermal degradation occurs in insulating sheath
Solution Approach 1:
The thermal welding process (resistance welding) is replaced with a mechanical-vibrational process (ultrasonic joining). The tin-plated joining portion enables solid-state ultrasonic bonding through mechanical vibration and pressure, eliminating the need for heat and preventing thermal degradation of the insulating sheath while achieving strong joint strength.
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 corrosion, enhances the reliability of electrical connections, reduces production costs by eliminating the need for multiple plating processes, and maintains high productivity while ensuring stable electrical characteristics.
Implementation Method 1
an uneven shape is formed on at least a part of a surface of the connection portion, and when the terminal-equipped electric wire is connected to the connection target member, an insulating coating of the plating layer covering the at least part of the surface of the connection portion is broken
Implementation Method 2
an electric wire to be connected to the terminal by ultrasonic joining
Data Source
AI summary
A terminal-equipped electric wire includes a terminal to be electrically connected to a connection target member, and an electric wire to be connected to the terminal by ultrasonic joining. The terminal includes a joint portion to be connected to the electric wire, a connection portion to be connected to the connection target member, and a plating layer on a surface of the terminal. The connection portion has an uneven shape on at least a part of a surface thereof. When the terminal-equipped electric wire is connected to the connection target member, an insulating coating of the plating layer covering at least a part of the surface of the connection portion is broken.