Tin-Bonded Terminal Wire Crimp for Small Vibration-Resistant Connectors
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Solution Overview
Problem
The increasing number of electric components in automobiles requires a reduction in the size of terminal-equipped electric wire connectors while maintaining the strength of the connection between the conductor and terminal, as existing methods struggle to ensure a secure connection, especially under vibration.
Innovation Solution
A terminal-equipped electric wire configuration featuring a conductor with a tin layer and a shell with a pressing portion that pinches the terminal, forming a tin adhering portion for a strong connection, reducing the conductor's cross-sectional area to 0.13 mm² or less, and using a Cu—Sn or Cu—Ag alloy for enhanced strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the conductor cross-sectional area is reduced to minimize connector size, then the connector size is reduced, but the connection strength between conductor and terminal deteriorates
Solution Approach 1:
The patent applies composite materials by combining copper conductor with tin plating layer, creating a Cu-Sn composite structure. The tin layer forms an adhering portion with the terminal that provides superior bonding strength compared to copper alone, enabling smaller conductors to maintain strong connections. This composite approach allows reduction of conductor cross-sectional area while compensating for reduced bulk material strength through enhanced interfacial bonding.
Solution Approach 2:
The patent changes the chemical composition parameters of the conductor surface by applying tin plating with specific thickness (0.3-1.0 μm) and controlling the oxide coating characteristics. These parameter changes create an adhering portion with optimized bonding properties, allowing the connection strength to be maintained or enhanced even as the overall conductor size is reduced for miniaturization.
2Ease of manufacture
If conventional crimping methods are used to connect conductor and terminal, then the connection is simple to manufacture, but the connection strength under vibration is insufficient
Solution Approach 1:
The patent replaces pure mechanical crimping connection with a chemical-mechanical bonding system. The tin plating layer undergoes oxidation to form an oxide coating, and tin metal migrates through this oxide layer to create an adhering portion that bonds chemically with the terminal. This substitution of mechanical bonding with chemical-metallurgical bonding provides superior vibration resistance while maintaining manufacturing simplicity through standard crimping processes.
Solution Approach 2:
The patent changes the physical-chemical parameters of the connection interface by controlling tin layer thickness, oxide coating formation, and tin migration characteristics. These parameter changes transform the connection mechanism from purely mechanical interlocking to a combination of chemical bonding and metallurgical adhesion, significantly improving reliability under vibrational conditions.
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 configuration provides a significant increase in the holding force between the conductor and terminal, ensuring a secure connection even under vibration, while minimizing the connector's size and reducing material usage, thus addressing the need for smaller, stronger connectors.
Implementation Method 1
an oxide coating formed on a surface of the tin layer
Implementation Method 2
an adhering portion formed of a portion of tin contained in the tin layer that passes through the oxide coating and pours out onto a surface of the oxide coating
Data Source
AI summary
A terminal-equipped electric wire includes an electric wire that includes a conductor, a terminal connected to the conductor, and a shell attached to the terminal. The conductor has a nominal cross-sectional area of 0.13 mm2 or less. The terminal includes a grip portion that pinches the conductor. The shell includes a pressing portion that presses at least a portion of the grip portion toward the conductor. At least one of the conductor and the grip portion includes a tin layer, and an oxide coating formed on the surface of the tin layer. An adhering portion formed of a portion of tin contained in the tin layer that passes through the oxide coating and pours out onto a surface of the oxide coating. The adhering portion has an area of 0.100 mm2 or more.