Cu-Ni-Si Copper Alloy Sheet for Smooth Precision Etching
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Solution Overview
Problem
Current Cu-Ni-Si based copper alloy sheet materials for high-precision lead frames face challenges in achieving high strength, surface smoothness, and dimensional accuracy, particularly in precision etching and pin formation with narrow widths.
Innovation Solution
The solution involves optimizing the Cu-Ni-Si based copper alloy by controlling the KAM value through appropriate cold rolling and annealing processes, using a large-diameter work roll for finish cold rolling, and strict tension and cooling rate control to enhance surface smoothness and flatness, while maintaining high strength and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the strength of the material is increased to achieve narrower pin width, then the pin width can be reduced, but the surface smoothness of the etched surface deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (Ni: 1.5-3.6%, Si: 0.3-1.0%, Co: 0.01-2.0%) and processing parameters (cold rolling reduction ratio: 5-20%, annealing temperature: 200-400°C, annealing time: 1-10 hours) to achieve both high strength and good surface smoothness simultaneously
Solution Approach 2:
The patent employs dynamics by implementing a multi-stage processing sequence that dynamically adjusts the material properties: first cold rolling to introduce strain and refine grain structure, then annealing to relieve stress and restore ductility, creating an optimal balance between strength and surface quality for precision etching
2Length of moving object
If the strength of the material is increased to achieve narrower pin width, then the pin width can be reduced, but the dimensional accuracy of the lead frame deteriorates
Solution Approach 1:
The patent applies preliminary action by performing cold rolling and annealing treatments before the precision etching process. These preliminary treatments pre-establish the optimal microstructure and mechanical properties, ensuring that the material can maintain dimensional accuracy during subsequent high-precision manufacturing operations
Solution Approach 2:
The patent controls composition parameters (Ni: 1.5-3.6%, Si: 0.3-1.0%, Co: 0.01-2.0%) and processing parameters (cold rolling reduction ratio: 5-20%, annealing temperature: 200-400°C, annealing time: 1-10 hours) to achieve both high strength and good surface smoothness simultaneously
3Strength
If cold rolling and annealing processes are applied to increase strength, then the strength improves, but the surface smoothness and flatness deteriorate
Solution Approach 1:
The patent optimizes the cold rolling reduction ratio to a specific range (5-20%) and controls annealing parameters (temperature: 200-400°C, time: 1-10 hours) to achieve the right balance between strength enhancement and surface quality preservation. The controlled parameters ensure sufficient grain refinement for strength while minimizing surface degradation
Solution Approach 2:
The patent employs a dynamic processing sequence where cold rolling is followed by annealing. The cold rolling stage introduces strain and refines the grain structure to increase strength, while the subsequent annealing stage relieves internal stress and restores surface smoothness, creating an optimal balance between strength and surface quality
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-Ni-Si based copper alloy sheet material with improved surface smoothness, high strength, and excellent dimensional accuracy, making it suitable for high-precision components like lead frames with narrow pins.
Implementation Method 1
an appropriate strain by cold rolling is applied between the solution treatment and the aging treatment
Implementation Method 2
solution treatment water quenching aging (525 °C, 3 hours)
Implementation Method 3
aging (525 °C, 3 hours) cold rolling (90%) aging (325 - 400 °C, 17- 20 hours)
Implementation Method 4
in the final low temperature annealing, the temperature rising rate is controlled, so as not to become excessively large
Implementation Method 5
the work roll for the finish cold rolling performed after the aging treatment has a large diameter, and the single rolling reduction ratio in the final pass is restricted
Implementation Method 6
in the shape correction with a tension leveler, the elongation rate is strictly controlled, so as to prevent excessive work from being applied
Implementation Method 7
a copper alloy which includes, by mass, 1.5 to 3.6% Ni, 0.3 to 1.0% Si, and the remainder consisting of copper... the copper alloy inter alia has a KAM value of 1.0 to 3.0
Data Source
AI summary
[Problem] A high strength Cu-Ni-Si based copper alloy sheet material excellent in surface smoothness of the etched surface is provided. [Solution] A copper alloy sheet material having: a composition containing, in terms of percentage by mass, from 1.0 to 4.5% of Ni, from 0.1 to 1.2% of Si, from 0 to 0.3% of Mg, from 0 to 0.2% of Cr, from 0 to 2.0% of Co, from 0 to 0.1% of P, from 0 to 0.05% of B, from 0 to 0.2% of Mn, from 0 to 0.5% of Sn, from 0 to 0.5% of Ti, from 0 to 0.2% of Zr, from 0 to 0.2% of Al, from 0 to 0.3% of Fe, from 0 to 1.0% of Zn, the balance of Cu, and unavoidable impurities; having a number density of coarse secondary phase particles having a major diameter of 1.0 µm or more of 4.0 × 103 per square millimeter or less, on an observation surface in parallel to a sheet surface; and having a KAM value measured with a step size of 0.5 µm of more than 3.00, within a crystal grain assuming that a boundary with a crystal orientation difference of 15º or more by EBSD is a crystal grain boundary.