Cu-Fe-P Alloy Microstructure Control for Bendability
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Solution Overview
Problem
Current Cu—Fe—P copper alloys face challenges in achieving a balance between high strength, high electrical conductivity, and excellent bendability, particularly in semiconductor IC lead frames, where increasing strength and conductivity levels are required while maintaining compatibility with reduced size and weight demands, and existing microstructure control methods often compromise either strength or bendability.
Innovation Solution
A copper alloy sheet with specific microstructural characteristics, including orientation densities of Brass, S, and Copper orientations controlled within certain ranges, combined with optimal chemical composition and processing conditions, to achieve high strength and electrical conductivity while enhancing bendability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the contents of Fe and P are increased to increase strength, then strength is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (Fe: 0.01-3.0%, P: 0.01-0.3%) and microstructural parameters (orientation densities of Brass, S, and Copper orientations) to achieve the optimal balance between strength and electrical conductivity. This resolves the contradiction by finding specific parameter ranges where both properties are satisfied simultaneously.
2Strength
If solid-solution hardening elements (Sn, Mg) are added or cold rolling reduction ratio is increased to increase strength, then strength is improved, but bendability deteriorates
Solution Approach 1:
The patent changes the microstructural parameters by controlling the orientation densities (Brass orientation: 20 or less, sum of Brass+S+Copper orientations: 10-50) instead of relying on solid-solution hardening. This alternative approach to strength enhancement preserves bendability while achieving the required strength level.
Solution Approach 2:
The patent substitutes the mechanical strengthening mechanism (solid-solution hardening through Sn or Mg addition) with a microstructural control mechanism (orientation density control). This substitution resolves the contradiction by achieving strength through a different physical mechanism that does not compromise bendability.
3Strength
If cold rolling reduction ratio is increased to achieve high strength, then strength is improved, but bendability deteriorates
Solution Approach 1:
The patent optimizes the cold rolling parameters by controlling the final reduction ratio within specific ranges and managing the resulting orientation density distribution. This controlled parameter adjustment achieves high strength while maintaining bendability, resolving the contradiction between these two properties.
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 enables copper alloy sheets to exhibit high strength (150 Hv or more) and high electrical conductivity (75% IACS or more) while maintaining excellent bendability, suitable for applications like IC lead frames, without compromising other essential properties like press-moldability.
Implementation Method 1
Cu—Fe—P copper alloys exhibit high strength, high electrical conductivity, and high thermal conductivity when an intermetallic compound, e.g., Fe or Fe and P, is dispersed in a copper matrix
Implementation Method 2
chemical compounds containing Fe and P of 0.2 μm or less are homogeneously dispersed
Implementation Method 3
the bendability can be improved to some extent by grain refining or by controlling the state of dispersoids
Implementation Method 4
the orientation density of the Brass orientation is 20 or less, and the sum of the orientation densities of the Brass orientation, the S orientation, and the Copper orientation is 10 or more and 50 or less
Data Source
AI summary
A Cu—Fe—P copper alloy sheet which has the high strength and the high electrical conductivity compatible with excellent bendability is provided. The Cu—Fe—P copper alloy sheet contains 0.01% to 3.0% of Fe and 0.01% to 0.3% of P on a percent by mass basis, wherein the orientation density of the Brass orientation is 20 or less and the sum of the orientation densities of the Brass orientation, the S orientation, and the Copper orientation is 10 or more and 50 or less in the microstructure of the copper alloy sheet.