Copper Alloy Plate Surface Gradient for Low-Resistance Plating
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Solution Overview
Problem
Copper alloy plates with high Mg content face increased contact resistance and reduced adhesiveness due to Mg oxidation and diffusion during plating and heating processes, leading to reliability issues in electrical connections.
Innovation Solution
A copper alloy plate with a controlled Mg concentration gradient in the surface layer, where the surface Mg concentration is 0-30% of the center concentration, and a plating film formed using electrolytic plating with a current density of 0.1-60 A/dm², reduces oxidation and diffusion, enhancing adhesiveness and contact electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high Mg content is added to copper alloy to improve strength and weight reduction, then mechanical strength is improved, but contact resistance increases due to Mg oxidation
Solution Approach 1:
The patent applies local quality by creating a non-uniform Mg concentration distribution within the copper alloy plate. The surface layer contains suppressed Mg concentration to prevent oxidation and maintain low contact resistance, while the interior maintains high Mg concentration to provide mechanical strength. This spatial differentiation of material properties resolves the contradiction between strength and reliability.
Solution Approach 2:
The patent transitions from a uniform compositional approach to a depth-dependent compositional gradient. By controlling Mg concentration as a function of depth from the surface (creating a concentration gradient), the patent simultaneously achieves oxidation resistance at the surface and strength in the bulk, effectively adding a dimensional variable to the material design.
2Strength
If high Mg content is added to copper alloy to improve strength, then mechanical strength is improved, but adhesiveness of plating film deteriorates due to Mg diffusion
Solution Approach 1:
The patent suppresses Mg concentration specifically in the surface layer where plating film formation occurs, while maintaining high Mg content in the interior for strength. This local compositional control prevents Mg diffusion into the plating film during electrolytic plating, ensuring good adhesiveness without sacrificing bulk mechanical properties.
3Strength
If Mg concentration is uniformly high throughout the copper alloy plate, then mechanical strength is maximized, but oxidation and diffusion occur during plating and heating processes
Solution Approach 1:
The patent creates a compositional gradient where the surface layer has suppressed Mg concentration to prevent oxidation and diffusion during processing, while the interior maintains high Mg concentration for mechanical strength. This spatial differentiation eliminates the harmful effects at the surface while preserving bulk properties.
Solution Approach 2:
The patent establishes the suppressed Mg concentration in the surface layer before the electrolytic plating and heating processes occur. This preliminary compositional control prevents oxidation and diffusion issues during subsequent processing steps, rather than attempting to correct problems after they occur.
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 solution effectively suppresses Mg oxidation and diffusion, improving electrical connection reliability and adhesiveness of the plating film, maintaining mechanical properties while reducing contact electrical resistance.
Implementation Method 1
a plating film formed using electrolytic plating with a current density of 0.1-60 A/dm²
Data Source
AI summary
To improve adhesion between a plating film reducing contact electrical resistance and a copper alloy plate containing Mg. A copper alloy plate containing Mg of more than 1.2% by mass and 2% by mass or less and the balance Cu and inevitable impurities in a center portion in a plate thickness direction, in the copper alloy plate, a surface Mg concentration at a surface is 30% or less of a center Mg concentration at the center portion in the plate thickness direction, a surface layer portion having a depth from the surface to where a Mg concentration is 90% of the center Mg concentration is provided, and in the surface layer portion, the Mg concentration increases from the surface toward the center portion of the plate thickness direction with a concentration gradient of 0.2% by mass/μm or more and 50% by mass/μm or less.