Mg Copper Alloy Composition for Stress Relaxation and Bendability
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Solution Overview
Problem
Existing copper alloys used in electronic and electrical devices, such as terminals, bus bars, and lead frames, face challenges in achieving high strength, excellent stress relaxation resistance characteristics, and good bendability, especially when exposed to high-temperature environments.
Innovation Solution
A copper alloy with a composition containing 0.10 mass % or greater and 2.6 mass % or less of Mg, along with a balance of Cu and inevitable impurities, is developed. This alloy stabilizes dislocations through the formation of Cottrell atmospheres, enhancing stress relaxation resistance and bendability while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure copper material is used to achieve excellent electrical conductivity, then electrical conductivity is improved, but stress relaxation resistance characteristics deteriorate
Solution Approach 1:
The patent applies composite material principle by creating a copper alloy containing 0.005-0.1 mass% Mg in addition to Cu and inevitable impurities. This composite copper-Mg alloy structure combines the excellent electrical conductivity of copper with the stress relaxation resistance enhancement provided by Mg solid solution strengthening, resolving the contradiction between electrical conductivity and stress relaxation resistance.
Solution Approach 2:
The patent applies parameter changes principle by precisely controlling the Mg content within 0.005-0.1 mass% range. This controlled compositional parameter change optimizes the balance between electrical conductivity (maintained by limiting Mg content) and stress relaxation resistance (improved by sufficient Mg addition), allowing simultaneous achievement of both properties.
2Strength
If Mg content is increased to improve stress relaxation resistance characteristics, then stress relaxation resistance is improved, but electrical conductivity decreases
Solution Approach 1:
The patent applies parameter changes principle by establishing an optimal Mg content range of 0.005-0.1 mass%. Within this controlled parameter range, the alloy achieves sufficient stress relaxation resistance improvement while maintaining excellent electrical conductivity, thus resolving the trade-off between these two properties.
Solution Approach 2:
The patent applies partial action principle by adding a small but sufficient amount of Mg (0.005-0.1 mass%) rather than large quantities. This partial addition provides the necessary stress relaxation resistance enhancement without excessively compromising electrical conductivity, achieving an optimal balance.
3Strength
If strength is increased to improve stress relaxation resistance characteristics, then stress relaxation resistance is improved, but bendability deteriorates
Solution Approach 1:
The patent applies parameter changes principle by controlling Mg content within 0.005-0.1 mass% and managing the plastic deformation characteristics through the resulting dislocation structure. This controlled parameter change enables the material to achieve high strength and stress relaxation resistance while maintaining good bendability through appropriate dislocation arrangement.
Solution Approach 2:
The patent applies local quality principle by creating specific dislocation structures through controlled plastic deformation. The dislocations are arranged in a manner that provides local strengthening for stress relaxation resistance while maintaining overall material ductility and bendability, achieving both properties 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
The copper alloy exhibits improved stress relaxation resistance characteristics, elongation, and bendability, making it suitable for high-temperature applications in electronic and electrical devices without compromising strength.
Implementation Method 1
by utilizing Mg, which is an additive element, to form Cottrell atmosphere and promoting stabilization of dislocations
Implementation Method 2
the strength and the stress relaxation resistance characteristics can be improved without greatly decreasing the electrical conductivity, by solid-solutionizing Mg into the matrix of copper
Data Source
AI summary
This copper alloy has a composition containing Mg in an amount of 0.10 mass % or greater and 2.6 mass % or less, with a balance being Cu and inevitable impurities, in which in a plastic deformation region of a stress-strain curve obtained in a low-speed tensile test at a strain rate of 1.0×10−6/s, an average value of a period of a strain of a saw edge-shaped curve is 0.01% or greater and 1.0% or less, an average value of a difference in level of stress of the saw edge-shaped curve is 0.1 MPa or greater and 2 MPa or less, and there are five or more saw edge-shaped curves with a period of strain of 0.01% or greater and 1.0% or less and a difference in the level of stress of 0.1 MPa or greater and 2 MPa or less.