Terminal Plating Hardness Trade-off for Wear and Cracking
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Solution Overview
Problem
Existing terminal technologies for hybrid and electric vehicles face issues with wear resistance during mating and unmating, and bending workability due to high electrical resistance and susceptibility to oxidation, leading to reduced reliability and strength in crimp parts.
Innovation Solution
A terminal design featuring a connection part with a silver alloy plating layer of 250 Hv or more and a crimp part with a silver or silver alloy plating layer of less than 225 Hv, along with an underlayer, to enhance wear resistance and prevent cracking, thereby improving mating and unmating performance and bending workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the layer thickness of the silver or silver alloy layer is increased to withstand terminal mating and unmating, then wear resistance is improved, but plating time increases and material cost increases
Solution Approach 1:
The patent applies different plating layer configurations to different parts of the terminal: the connection part (mating surface) receives a silver alloy plating layer with high hardness (250 Hv or more) for wear resistance, while the crimp part receives a silver or silver alloy plating layer with lower hardness (less than 225 Hv) for bending workability. This local differentiation allows each part to have optimal properties without compromising the other.
Solution Approach 2:
The patent uses composite plating structures combining silver alloy layers with specific hardness characteristics. The connection part employs a silver alloy plating layer containing silver and at least one of tin, copper, palladium, bismuth, indium, or antimony, achieving a Vickers hardness of 250 Hv or more through controlled alloy composition and thickness (1 μm to 10 μm), while maintaining overall terminal performance.
2Strength
If the hardness of the silver alloy plating layer is increased to improve wear resistance, then mating and unmating performance is improved, but bending workability deteriorates due to cracking
Solution Approach 1:
The patent applies different plating layer configurations to different parts of the terminal: the connection part (mating surface) receives a silver alloy plating layer with high hardness (250 Hv or more) for wear resistance, while the crimp part receives a silver or silver alloy plating layer with lower hardness (less than 225 Hv) for bending workability. This local differentiation allows each part to have optimal properties without compromising the other.
3Quantity of substance
If tin plating is used to reduce cost, then material cost is reduced, but electrical resistance increases and heat resistance deteriorates
Solution Approach 1:
The patent uses composite plating structures combining silver alloy layers with specific hardness characteristics. The connection part employs a silver alloy plating layer containing silver and at least one of tin, copper, palladium, bismuth, indium, or antimony, achieving a Vickers hardness of 250 Hv or more through controlled alloy composition and thickness (1 μm to 10 μm), while maintaining overall terminal performance.
Data Source
AI summary
A terminal includes a connection part electrically connectable to a mating terminal, and a crimp part capable of crimping a cable. The connection part includes a first base having electrical conductivity, and a first plating layer that covers the first base, has a Vickers hardness of 250 Hv or more, and contains silver alloy containing silver. The crimp part includes a second base having electrical conductivity, and a second plating layer that covers the second base, has a Vickers hardness of less than 225 Hv, and contains either silver or silver alloy containing silver.