Connection Terminal Surface Layer with Indium Alloy
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Solution Overview
Problem
Existing metallic materials with precious metal layers on their surfaces, while providing low contact resistance, often fail to achieve a satisfactory reduction in friction coefficient, which is crucial for smooth sliding and reduced insertion/removal forces in electric connection members like connection terminals.
Innovation Solution
A metallic material with a surface layer containing a precious metal element, such as Ag or Au, and Indium (In), where In forms an alloy with the precious metal element, creating a high-concentration In portion and a precious metal portion, both exposed on the surface, which reduces friction coefficient and maintains low contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a precious metal layer (Ag, Au, Pt) is provided on the surface of a connection terminal, then low contact resistance and stable electric connection characteristic are achieved, but the friction coefficient remains high and sliding is not smooth
Solution Approach 1:
The surface layer is segmented into multiple functional regions: a precious metal portion (Ag, Au, or Pt) that provides low contact resistance and electrical stability, and a In portion that provides low friction and smooth sliding. This segmentation allows each region to independently fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the surface layer are assigned different material compositions and properties. The precious metal portion is localized to provide electrical conductivity and oxidation resistance, while the In portion is localized to provide lubrication and reduce friction. This local differentiation of material properties resolves the contradiction between electrical performance and friction characteristics.
2Ease of operation
If a hard metallic layer (e.g., Ag-Sn alloy) is provided on the lower layer of a precious metal layer, then the friction coefficient is reduced, but the surface characteristics are not sufficiently improved because the hard metallic layer does not directly contact the opposite member
Solution Approach 1:
The invention extracts the friction-reducing function from the underlying hard metallic layer and relocates it to the surface layer itself by incorporating In directly in the surface layer. This allows the low-friction material to be in direct contact with the opposite member, thereby directly affecting surface characteristics and achieving sufficient friction reduction.
Solution Approach 2:
In is introduced as an intermediary substance in the surface layer that mediates between the precious metal portion and the opposite connection terminal. This intermediary In portion directly contacts the opposite member and provides the lubricating effect, bridging the gap between the precious metal layer and the sliding surface.
3Ease of operation
If In is added to the surface layer to reduce friction coefficient, then smooth sliding is achieved, but contact resistance may increase due to lower electrical conductivity of In compared to precious metals
Solution Approach 1:
The surface layer is segmented into electrically conductive precious metal portions and friction-reducing In portions. This segmentation ensures that electrical contact occurs through the high-conductivity precious metal regions, while the In regions provide lubrication, thereby maintaining low contact resistance while achieving smooth sliding.
Solution Approach 2:
Different regions of the surface layer have different material properties optimized for their specific functions. The precious metal portions are localized to provide high electrical conductivity and low contact resistance, while the In portions are localized to provide low friction. This local differentiation allows the surface layer to simultaneously achieve low contact resistance and low friction coefficient.
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 surface layer achieves both low contact resistance and friction coefficient, ensuring stable electrical connectivity and smooth sliding, even at high temperatures, by leveraging the high conductivity of precious metals and the solid lubricating properties of In.
Implementation Method 1
at least part of In contained in the surface layer may be an alloy with the precious metal element
Implementation Method 2
These precious metals have high electric conductivity
Implementation Method 3
In is a soft metal and exhibits a solid lubricating action
Data Source
AI summary
A metallic material that includes a foundation material; and a surface layer formed on a surface of the foundation material and exposed on an outermost surface, wherein the surface layer contains a precious metal element made of at least one kind selected from the group consisting of Ag, Au, and a platinum group element, and In, and a connection terminal being made of the metallic material, wherein the surface layer is formed on a surface of the foundation material, at least in a contact portion electrically contacting an opposite electrically conductive member.