Silver-Carbon Composite Coating for Low-Friction Connector Terminals

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Solution Overview

Problem

Conventional silver-plated materials for sliding contact parts have a high coefficient of friction, limiting their applications, and existing composite materials with graphite particles in a silver matrix do not fully meet the requirement for low insertion force due to silver adhesion issues.

Innovation Solution

A composite material with an oxygen-containing silver-based coating layer formed on a copper or copper alloy base material, where the coating layer contains carbon particles and has oxygen present in the vicinity of its surface, reducing the coefficient of friction through plasma treatment in the presence of oxygen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If silver plating is used for sliding contact parts, then electrical conductivity and oxidation resistance are improved, but coefficient of friction increases

Engineering Contradiction:
Improveelectrical conductivity and oxidation resistanceVSAvoidcoefficient of friction
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The invention uses a composite coating layer containing silver particles and carbon particles (graphite, carbon black, or amorphous carbon) dispersed in a silver matrix. This composite structure combines the excellent electrical conductivity and oxidation resistance of silver with the low friction and wear resistance of carbon particles, resolving the contradiction between reliability and coefficient of friction

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The coating layer is designed with non-uniform distribution of carbon particles within the silver matrix, creating local regions with different properties. The carbon particles are concentrated at specific locations to provide lubrication where needed, while maintaining silver's conductive properties in other areas, thus achieving low friction without sacrificing electrical conductivity

Inventive Principle:
Principle #3Local quality

2Strength

If graphite particles are dispersed in silver matrix, then wear resistance is improved, but silver adhesion occurs during sliding

Engineering Contradiction:
Improvewear resistanceVSAvoidsilver adhesion
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The carbon particles act as an intermediary substance between sliding surfaces. They form a lubricating film that prevents direct contact between silver surfaces, thereby eliminating silver adhesion while maintaining wear resistance. The carbon particles are consumed during sliding to continuously replenish the lubricating film

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The carbon particles are pre-dispersed in the silver matrix during coating formation, so they are already in position to provide lubrication before sliding begins. This preliminary arrangement ensures immediate wear resistance and prevents silver adhesion from the start of operation

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If connector is made multipolar to increase terminal count, then functionality is improved, but insertion force increases

Engineering Contradiction:
Improveterminal count and functionalityVSAvoidinsertion force
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The invention changes the friction parameter of the terminal coating by using a silver-carbon composite material with significantly lower coefficient of friction compared to conventional silver plating. This parameter change reduces the insertion force required for multipolar connectors, making them easier to assemble despite having more terminals

Inventive Principle:
Principle #35Parameter changes

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 material achieves a significantly lower coefficient of friction, making it suitable for applications requiring low insertion force while maintaining excellent electrical conductivity and oxidation resistance.

Implementation Method 1

applying plasma treatment under a presence of oxygen to a surface of a coating layer

Methodology Applied
Scientific EffectPlasma treatment: Plasma

Implementation Method 2

graphite particles among carbon particles such as graphite and carbon black, which are excellent in wear resistance and lubricity, are dispersed in a silver matrix

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

by electroplating using a silver plating solution in which carbon particles from which surface lipophilic organic matters have been removed by oxidation and a silver matrix alignment modifier (potassium selenocyanate) are added

Methodology Applied
Scientific EffectElectroplating: Electroplating

Implementation Method 4

carbon particles from which surface lipophilic organic matters have been removed by oxidation

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentUS20240287699A1Composite material, method for manufacturing composite material, terminal and method for manufacturing terminal
Publication Date: 2024.08.29 DOWA METALTECH CO LTD

AI summary

There is provided a composite material in which an oxygen-containing silver-based coating layer is formed on a base material. the oxygen-containing silver-based coating layer containing silver and having oxygen present in the vicinity of its surface. and the base material comprising copper or copper alloy.