Electroconductive Material for Automotive Connectors
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Solution Overview
Problem
Conventional Sn-plated electroconductive materials for connection components in automobiles face challenges in reducing frictional coefficient and fretting corrosion, leading to increased connector inserting force and contact resistance due to vibration, which affects electrical reliability and productivity.
Innovation Solution
An electroconductive material with a copper alloy base member, a Cu—Sn alloy coating layer having 20-70% Cu content, and a Sn coating layer, subjected to reflow treatment, with a surface roughness of 0.15-3.0 μm and 3-75% exposed Cu—Sn alloy area ratio, featuring random microstructures and streak microstructures parallel to the rolled direction, which reduces frictional coefficient and enhances fretting corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the contacting pressure between terminals is lowered to decrease connector inserting force, then the inserting force is reduced, but fretting corrosion is generated due to vibration causing Sn plating abrasion and increased contact resistance
Solution Approach 1:
The patent applies local quality by creating a multi-layer coating structure with different properties at different depths: the Sn coating layer provides low friction and corrosion resistance at the surface, while the Cu-Sn alloy coating layer provides mechanical strength and wear resistance underneath. This layered structure allows the surface to have low frictional coefficient for easy insertion while the underlying layer prevents fretting corrosion during vibration.
Solution Approach 2:
The patent uses composite materials by combining Sn plating with Cu-Sn alloy coating in a layered structure. The Sn layer provides excellent corrosion resistance and low friction, while the Cu-Sn alloy layer provides mechanical strength and wear resistance. This composite structure resolves the contradiction by allowing low contacting pressure for easy insertion while preventing fretting corrosion through the combined properties of the two materials.
2Ease of operation
If the Cu—Sn alloy coating layer is made harder to decrease frictional coefficient, then the frictional coefficient is reduced, but the shaping processability and productivity are affected
Solution Approach 1:
The patent applies parameter changes by controlling the Cu content in the Cu-Sn alloy coating layer within a specific range (20-70% by atom) and adjusting the thickness of the Cu-Sn alloy layer (0.2-3.0 μm). By optimizing these parameters, the coating achieves a balance between hardness for low friction and sufficient ductility for shaping processability. The Sn coating layer thickness (0.2-5.0 μm) is also controlled to maintain low friction while allowing the underlying Cu-Sn layer to provide mechanical support.
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 material achieves a lower frictional coefficient and improved fretting corrosion resistance, reducing connector inserting force and maintaining electrical reliability, while maintaining productivity and shaping processability.
Implementation Method 1
a surface of the material is subjected to reflow treatment and has an arithmetic average roughness Ra of 0.15 μm or more in one or more direction(s) along the surface
Data Source
AI summary
An electroconductive material for a connection component have a base member made of a copper alloy plate, a Ni coating layer, a Cu—Sn alloy coating layer, and a Sn coating layer. A surface of the material is subjected to reflow treatment. The base member surface is roughened. The Cu—Sn alloy coating layer is partially exposed from the outside surface of the Sn coating layer. Regions of the Cu—Sn alloy coating layer exposed to the outside surface of the Sn coating layer have random microstructures distributed irregularly between portions of the Sn coating layer and streak microstructures extending in parallel to a rolled direction of the base member. The streak microstructures having a length of 50 μm or more and a width of 10 μm or less are contained in a number of 35 or more per 1 mm2.