Silver-Tin Alloy Terminal Plating for Abrasion and Contact Resistance
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Solution Overview
Problem
Terminal plating materials for hybrid and electric vehicles face challenges with high abrasion resistance and contact resistance, particularly when using silver or silver alloy plating, which requires increased layer thickness and material usage, and may generate heat due to high electric resistance.
Innovation Solution
A terminal plating material with a silver-tin alloy layer containing an intermetallic compound, having a Vickers hardness of 250 Hv or more and surface roughness of 0.60 μmRa or less, which provides high abrasion resistance while minimizing contact resistance and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver or silver alloy plating is used to reduce electric resistance, then contact resistance is reduced, but abrasion resistance deteriorates
Solution Approach 1:
The invention uses a composite plating structure with multiple layers: a silver-tin alloy plating layer containing intermetallic compounds (Ag3Sn, Ag5Sn, or Ag4Sn) as the outermost layer, and optionally a nickel plating layer as the base layer. This composite structure combines the low contact resistance of silver with the high abrasion resistance provided by the intermetallic compounds and nickel layer, resolving the contradiction between electrical conductivity and mechanical durability.
2Strength
If the plating layer thickness is increased to improve abrasion resistance, then abrasion resistance is improved, but plating time and material usage increase
Solution Approach 1:
The invention changes the chemical composition parameters of the plating layer by incorporating specific intermetallic compounds (Ag3Sn, Ag5Sn, or Ag4Sn) with defined tin content ranges (3-10 mass%, 10-15 mass%, or 15-20 mass% respectively). These compositional changes dramatically improve surface hardness and abrasion resistance, allowing thin plating layers (5-20 μm) to achieve the same durability as much thicker traditional silver plating, thus reducing plating time and material consumption.
3Quantity of substance
If tin plating is used to reduce cost, then material cost is reduced, but electric resistance increases causing heat generation
Solution Approach 1:
The invention applies local quality by creating a multi-layered plating structure where different layers serve different functions: the nickel base layer provides corrosion resistance and structural integrity, while the silver-tin alloy outer layer with intermetallic compounds provides low contact resistance and high conductivity. This localized functional distribution allows the use of cheaper materials (nickel, tin) in the base layers while maintaining the electrical performance of expensive silver at the critical contact surface, reducing overall material cost without sacrificing electrical performance.
Data Source
AI summary
A terminal plating material includes a metal substrate, and a silver-tin alloy plating layer containing a silver-tin alloy, arranged on the metal substrate. The silver-tin alloy plating layer contains an intermetallic compound of silver and tin, the Vickers hardness of the surface of the silver-tin alloy plating layer in the terminal plating material is 250 Hv or more, and the surface roughness of the silver-tin alloy plating layer is 0.60 μmRa or less. Further, a terminal is formed from the terminal plating material. A terminal-equipped electric wire includes the terminal. A wire harness includes the terminal-equipped electric wire.