Silver-Carbon Composite Coating for Copper Diffusion Resistance
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Solution Overview
Problem
Existing composite materials for sliding electrical contact parts, such as automotive switches and connectors, suffer from insufficient reliability due to copper diffusion and oxidation, especially when exposed to high-temperature environments, leading to increased resistance and wear, and thicker coatings to mitigate this issue increase production costs.
Innovation Solution
A composite material with a composite coating containing carbon particles in a silver layer, where the carbon particles are surface-treated with specific compounds to form protrusions, providing excellent reliability even with a thin coating, achieved through electroplating using a silver plating solution containing surface-treated carbon particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the composite coating is made thinner to reduce production cost, then production cost is reduced, but copper diffusion and oxidation increases leading to insufficient reliability
Solution Approach 1:
The invention applies local quality by creating protrusions at specific locations on the composite coating surface. These protrusions are formed by aggregating carbon particles with oxidized surfaces at the coating surface, while the bulk coating remains thin. This localized structural modification prevents copper diffusion and oxidation at critical areas without requiring the entire coating to be thick, thus maintaining reliability while reducing production cost.
Solution Approach 2:
The invention applies preliminary action by pre-oxidizing the surface of carbon particles before electroplating. The carbon particles are treated with an oxidizing agent to create oxidized surfaces that have high affinity for copper diffusion blocking. This preliminary treatment ensures that when the particles are incorporated into the composite coating, they immediately function as effective barriers against copper diffusion, enabling thin coating design with sufficient reliability.
2Reliability
If the composite coating is made thicker to prevent copper diffusion, then reliability is improved, but production cost increases
Solution Approach 1:
Instead of uniformly thickening the coating, the invention creates localized protrusions at the coating surface where carbon particles with oxidized surfaces aggregate. These protrusions provide enhanced copper diffusion blocking at critical surface areas, achieving the reliability benefits of thick coating only where needed, while the rest of the coating remains thin to minimize production cost.
Solution Approach 2:
The invention uses composite materials by incorporating carbon particles with oxidized surfaces into the silver-based composite coating. The oxidized carbon particles create a composite structure with enhanced barrier properties against copper diffusion, allowing the coating to achieve high reliability at reduced thickness compared to conventional homogeneous silver coatings.
3Object-affected harmful factors
If silver plating is applied to prevent oxidation of conductive material, then oxidation resistance is improved, but wear resistance decreases due to softness and high friction coefficient
Solution Approach 1:
The invention creates a composite coating by dispersing carbon particles throughout the silver matrix. The carbon particles provide wear resistance and lubricity, compensating for the softness of silver, while the silver matrix maintains oxidation resistance. The composite structure combines the advantages of both materials, achieving both oxidation resistance and wear resistance simultaneously.
Solution Approach 2:
The invention applies local quality by concentrating oxidized carbon particles at the coating surface to form protrusions. These surface protrusions provide enhanced wear resistance and lubrication at the contact interface, while the bulk silver matrix maintains its oxidation resistance. This spatial differentiation of functions resolves the contradiction between oxidation resistance and wear 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 composite material exhibits enhanced reliability and wear resistance with a thin coating, maintaining electrical conductivity and reducing copper diffusion, thus addressing the limitations of previous technologies.
Implementation Method 1
carbon particles that have been subjected to a surface treatment with an oxidizing agent
Implementation Method 2
electroplating is performed using a silver plating solution containing the carbon particles
Data Source
AI summary
There is provided a composite material in which a composite coating composed of a silver layer containing carbon particles is provided on a base material, wherein when the composite coating is observed with a laser microscope, a proportion of predetermined protrusions in an observation field is 12% or more by area.