Mg-Cu Alloy Bendability and Conductivity

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Solution Overview

Problem

Copper alloys used in electronic and electric devices face challenges in maintaining high bendability and electrical conductivity, especially with increasing thickness, as they require improved uniform elongation and heat resistance without compromising conductivity.

Innovation Solution

A copper alloy composition with Mg between 0.1-0.5 mass%, P between 1-100 mass ppm, Sn between 10-1000 mass ppm, and limited H, O, and S content, which undergoes specific heat treatment to enhance work-hardening rate and conductivity, ensuring excellent bendability and electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If copper alloy thickness is increased to handle high current and voltage, then electrical conductivity and current carrying capacity are improved, but bendability deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidbendability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention changes the chemical composition parameters of the copper alloy by precisely controlling Mg content (0.1-0.5 mass%), P content (1-100 mass ppm), Sn content (10-1000 mass ppm), and impurity levels (H<4 mass ppm, O<10 mass ppm, S<40 mass ppm). This compositional parameter optimization enables the material to achieve both high electrical conductivity and excellent bendability, resolving the contradiction between thickness-related conductivity improvement and bendability deterioration

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite microstructure within the copper alloy by forming fine precipitates of Mg2Sn and Mg3P2 phases distributed throughout the copper matrix. This composite structure at the micro level provides both the electrical conductivity needed for thick sections and the ductility required for bendability, allowing the material to satisfy both opposing requirements simultaneously

Inventive Principle:
Principle #40Composite materials

2Strength

If Mg content is increased to improve strength and bendability, then mechanical properties are improved, but electrical conductivity deteriorates

Engineering Contradiction:
ImprovebendabilityVSAvoidelectrical conductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention optimizes the Mg content parameter within a narrow range of 0.1-0.5 mass%, which is sufficient to achieve the desired strength and bendability through precipitate formation while minimizing the negative impact on electrical conductivity. This precise parameter control resolves the contradiction between mechanical property improvement and conductivity maintenance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention forms a composite structure where Mg-based precipitates (Mg2Sn and Mg3P2) are distributed in the copper matrix. These fine precipitates provide strengthening and improve bendability through precipitation hardening, while their small volume fraction and fine distribution minimize the disruption to electrical conductivity pathways in the copper matrix

Inventive Principle:
Principle #40Composite materials

3Strength

If P content is increased to improve bendability and stress relaxation resistance, then mechanical properties are improved, but electrical conductivity and manufacturing precision deteriorate

Engineering Contradiction:
Improvebendability and stress relaxation resistanceVSAvoidelectrical conductivity
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention precisely controls the P content parameter within 1-100 mass ppm, which is the optimal range to achieve improved bendability and stress relaxation resistance through Mg3P2 precipitate formation, while keeping P content low enough to minimize its harmful effect on electrical conductivity and manufacturing precision

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 alloy achieves improved uniform elongation, high electrical conductivity, and heat resistance, making it suitable for thick components in electronic devices while maintaining reliability and reducing defects.

Implementation Method 1

undergoes specific heat treatment to enhance work-hardening rate and conductivity

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

high electrical conductivity

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3348658B1Copper alloy for electronic/electrical device, plastically-worked copper alloy material for electronic/electrical device, component for electronic/electrical device, terminal and busbar
Publication Date: 2022.01.26 MITSUBISHI MATERIALS CORP
  • EP3348658B1 patent drawingFigure 1
  • EP3348658B1 patent drawingFigure 2
  • EP3348658B1 patent drawing

AI summary

The present invention is characterized by containing 0.1 to less than 0.5 mass% of Mg, the balance being Cu and unavoidable impurities, and is further characterized in that in a tension test, when the ratio dσt/dεt defined by true stress σt and true strain εt is plotted on the vertical axis and true strain εt is plotted on the horizontal axis, a strain region is included in which the gradient of dσt/dεt is positive.