Connector Terminal Material With Silver-Nickel Plating for Heat and Wear
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Solution Overview
Problem
Existing terminal materials for connectors face issues with abrasion resistance and heat resistance, particularly due to the deterioration of silver-plating layers over time and increased contact resistance from antimony diffusion in high-temperature environments.
Innovation Solution
A terminal material with a copper or copper alloy base, a nickel-plating layer, and a silver-nickel alloy plating layer with specific thickness and nickel content ranges, which suppresses crystal grain coarsening and diffusion, maintaining low friction and high abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crystal grain size of the silver-plating layer is increased to reduce copper diffusion, then the abrasion resistance deteriorates over time in high temperature environments
Solution Approach 1:
The patent applies local quality by creating a multi-layer plating structure where each layer has different crystal grain sizes optimized for its specific function. The first silver-plating layer has larger crystal grains (5μm or more) to prevent copper diffusion, while the second silver-plating layer has smaller crystal grains (0.1μm or less) to maintain abrasion resistance. This local differentiation of crystal grain sizes allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
The patent employs composite materials by combining multiple plating layers with distinct properties into a unified coating system. The composite structure consists of a base material, nickel-plating layer, first silver-plating layer with large crystal grains, and second silver-plating layer with small crystal grains. This composite approach allows the system to simultaneously achieve copper diffusion prevention and maintained abrasion resistance under high temperature conditions.
2Strength
If the film thickness of the silver-plating layer is increased to compensate for abrasion resistance deterioration, then the manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by optimizing the crystal grain size parameter rather than simply increasing film thickness. By controlling the crystal grain size of the second silver-plating layer to be 0.1μm or less through specific plating conditions, the patent achieves excellent abrasion resistance with a thinner total film thickness, thereby reducing material costs while maintaining performance.
3Strength
If antimony is added to the silver-plating layer to increase hardness and abrasion resistance, then contact resistance increases due to oxidization after antimony diffusion to the outermost surface
Solution Approach 1:
The patent extracts the harmful element (antimony) from the plating structure and replaces it with nickel, which provides the desired hardness and abrasion resistance without the harmful oxidation effect. By taking out antimony and substituting it with nickel in the first silver-plating layer, the patent achieves improved abrasion resistance while preventing contact resistance increase.
Solution Approach 2:
The patent uses nickel as a sacrificial or protective layer that prevents the oxidation of the outermost silver layer. The nickel-plating layer and first silver-plating layer with nickel act as a protective barrier, allowing the second silver-plating layer to maintain its low contact resistance properties while the underlying nickel-containing layers provide the necessary hardness and abrasion resistance.
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 enhances both abrasion and heat resistance while preventing contact resistance increases in high-temperature environments, ensuring reliable performance.
Implementation Method 1
a nickel-plating layer made of nickel or nickel alloy coating a surface of the base material... copper of the base material is restrained to be diffused into the second silver-plating layer
Implementation Method 2
a silver-nickel alloy plating layer formed on at least a part of the nickel-plating layer... having a nickel content 0.03 at % or more and 1.20 at % or less, and an average crystal grain size 10 nm or more and 150 nm or less
Data Source
AI summary
Providing a terminal material for connectors provided with a base material in which at least a surface layer is made of copper or copper alloy, a nickel-plating layer made of nickel or nickel alloy coating a surface of the base material, and a silver-nickel alloy plating layer formed on at least a part of the nickel-plating layer, the silver-nickel alloy plating layer having a film thickness of 0.5 μm to 20 μm inclusive, a nickel content of 0.03 at % to 1.20 at % inclusive, and an average crystal grain size of 10 nm to 150 nm inclusive, to improve abrasion resistance and heat resistance.