Thin Ni Underlayer and Ag Plated Layer for Vehicle Terminals
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Solution Overview
Problem
Conventional Ag-plated materials on copper or copper alloys for vehicle terminals face issues with high production costs due to thick Ag layers required for heat resistance and increased insertion-extraction force from viscosity of corrosion inhibitors, leading to increased contact resistance and corrosion product deposition.
Innovation Solution
A plated material with a thin Ni underlayer (0.1 μm to 1.0 μm) and a thin Ag plated layer (1.0 μm or less) is used, where the Ag plated layer has a surface Vickers hardness of 65 or more, reducing corrosion product deposition and contact resistance, and eliminating the need for viscosity-based corrosion inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the Ag plated layer is increased to 5 μm or more to suppress corrosion product deposition, then corrosion resistance is improved, but production cost increases due to the high price of silver
Solution Approach 1:
The patent changes the thickness parameter of the Ag plated layer from the conventional 5 μm or more to 1.0 μm or less, while simultaneously optimizing the Ni underlayer thickness to 0.1-1.0 μm. This parameter change reduces silver consumption and production cost while maintaining corrosion resistance through the optimized multi-layer structure that suppresses galvanic corrosion.
Solution Approach 2:
The patent uses a composite plated layer structure consisting of multiple layers with different materials (Ni underlayer, Ag plated layer, and optionally Pd or Pt outer layer). This composite structure provides synergistic effects where the Ni layer suppresses galvanic corrosion and the Ag layer provides low contact resistance, achieving both corrosion resistance and cost efficiency.
2Reliability
If a corrosion inhibitor is applied to the surface of the Ag plated layer to fill pinholes and suppress corrosion product deposition, then corrosion resistance is improved, but insertion-extraction force increases due to the viscosity of the corrosion inhibitor
Solution Approach 1:
The patent extracts and eliminates the corrosion inhibitor substance from the terminal structure. Instead of applying a corrosive inhibitor that increases insertion-extraction force, the invention uses a corrosion-resistant plated layer structure (Ni underlayer + Ag plated layer) that inherently suppresses corrosion without requiring additional viscous substances.
Solution Approach 2:
The patent introduces a Ni underlayer as an intermediary between the base metal and the Ag plated layer. This intermediate layer acts as a barrier that suppresses galvanic corrosion and prevents corrosion product deposition, replacing the need for corrosion inhibitors while maintaining low insertion-extraction force.
3Reliability
If only Ag plating is applied to copper or copper alloy to reduce contact resistance, then electrical conductivity is improved, but heat resistance deteriorates
Solution Approach 1:
The patent segments the plated layer into multiple functional layers: a Ni underlayer for heat resistance and corrosion suppression, and an Ag plated layer for electrical conductivity. This segmentation allows each layer to perform its specialized function, with the Ni layer providing thermal stability and the Ag layer providing low contact resistance.
Solution Approach 2:
The patent creates a composite plated structure combining Ni and Ag layers. The Ni underlayer provides high heat resistance and suppresses galvanic corrosion, while the Ag plated layer provides low contact resistance. This composite material approach achieves both heat resistance and electrical conductivity simultaneously.
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
This configuration suppresses corrosion product deposition at lower costs, maintains low contact resistance, and reduces insertion-extraction force, enabling application to small terminals without compromising performance.
Implementation Method 1
When a metal having a high ionization tendency is brought into contact with a metal having a low ionization tendency, galvanic corrosion (bimetallic corrosion) generally occurs. In contrast, nickel (Ni) is easily oxidized compared to copper (Cu), and electric potential difference is relatively large due to relatively different ionization tendencies
Implementation Method 2
a plated material in which Ag plating is applied to copper or a copper alloy as a base metal, for example, has been conventionally used for the purpose of reducing contact resistance, one of electrical characteristics
Implementation Method 3
copper (Cu) and silver (Ag) are not easily oxidized
Data Source
AI summary
A plated material includes a base metal made from Cu or an alloy containing Cu as a main raw material, an underlayer made from Ni formed on the base metal, and an Ag plated layer formed on the underlayer. A thickness of the underlayer is 0.1 μm to 1.0 μm. A thickness of the Ag plated layer is 1.0 μm or less.