Cu-Co-Si Alloy Aging for Strength-Conductivity Balance
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Solution Overview
Problem
Despite various proposals, the optimum conditions for aging in Cu—Co—Si alloys have not been established, leading to suboptimal precipitation of second phase particles, which affects the balance between electro-conductivity, strength, and bend formability, with existing methods insufficient for accurately measuring particle sizes below 10 nm.
Innovation Solution
The alloy composition is optimized with 0.5 to 3.0% Co, 0.1 to 1.0% Si, and a Co/Si ratio of 3.5 to 5.0, with ultrafine second phase particles of 1 to 50 nm in size and an average distance of 10 to 50 nm, controlled through precise aging processes to improve the balance of properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Cu—Ni—Si alloy is used to improve strength and electro-conductivity, then fine Ni—Si intermetallic compound grains deposit in copper matrix, but electro-conductivity cannot achieve 60% IACS or larger while keeping desirable strength
Solution Approach 1:
The patent changes the alloying element from Ni to Co, fundamentally altering the material parameters. Cu—Co—Si alloy with specific composition ranges (Co: 0.5-3.0%, Si: 0.1-1.0%, Co/Si ratio: 3.5-5.0) enables formation of Co2Si precipitates instead of Ni—Si intermetallic compounds, achieving both high strength (≥650 MPa) and high electro-conductivity (≥60% IACS) simultaneously
Solution Approach 2:
The patent creates a composite microstructure consisting of a copper matrix with dispersed Co2Si intermetallic compound precipitates. This composite structure combines the high electro-conductivity of copper matrix with the strength-enhancing effect of fine Co2Si particles, resolving the contradiction between strength and electro-conductivity
2Strength
If aging process is applied to control distribution and grain size of cobalt silicide deposits, then strength is improved, but optimal conditions for balancing electro-conductivity, strength, and bend formability are not established
Solution Approach 1:
The patent establishes specific aging process parameters: temperature range of 400-600°C and time range of 1-10 hours. These parameter ranges optimize the precipitation of Co2Si particles to achieve average grain sizes of 5-50 nm, simultaneously improving strength (≥650 MPa) and electro-conductivity (≥60% IACS) while maintaining bend formability
Solution Approach 2:
The patent replaces complex multi-step processing with a simplified single-step aging process that achieves optimal distribution and grain size of Co2Si precipitates. The controlled aging treatment substitutes for multiple sequential operations, reducing process complexity while maintaining or improving the balance among strength, electro-conductivity, and bend formability
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
This approach results in a Cu—Co—Si alloy with enhanced strength, electro-conductivity, and bend formability, achieving a 0.2% yield strength of 500 to 650 MPa and electro-conductivity of 65 to 75% IACS, suitable for electronic components.
Implementation Method 1
a precipitation-hardened copper alloy
Implementation Method 2
subsequent aging at 400° C. or above and 600° C. or below, for 2 hours or longer and 8 hours or shorter
Implementation Method 3
solution treatment, and subsequent aging
Data Source
AI summary
Disclosed is a copper-cobalt-silicon (Cu—Co—Si) alloy for electronic material with an improved balance among electro-conductivity, strength and bend formability, which includes 0.5 to 3.0% by mass of Co, 0.1 to 1.0% by mass of Si, and the balance of Cu and inevitable impurities, having a ratio of mass percentages of Co and Si (Co/Si) given as 3.5≤Co/Si≤5.0, having an average particle size of second phase particles, within the range of the particle size of 1 to 50 m seen in a cross-section taken in parallel with the direction of rolling, of 2 to 10 nm, and having an average distance between the adjacent second phase particles of 10 to 50 nm.