Titanium Copper Foil Strength and Bending Workability
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Solution Overview
Problem
The miniaturization of autofocus camera modules leads to settling issues with existing titanium copper foils, and they crack during bending, due to insufficient strength and bending workability.
Innovation Solution
A titanium-copper foil with a Ti content of 2.0 to 4.0 mass % and a 0.2% yield strength of 1000 MPa or more in both directions parallel and perpendicular to the rolling direction, along with a spring limit value of 800 MPa or more, is produced through hot and cold rolling, solution treatment, and controlled aging to ensure high strength and bending workability without cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium copper foil is used to reduce material cost, then cost is reduced, but strength is insufficient causing settling
Solution Approach 1:
The patent changes the chemical composition parameters by precisely controlling Ti content (2.0-4.0 mass%) and Cu content (95.0-98.0 mass%), and adjusts processing parameters including solution treatment temperature (700-1000°C), aging temperature (200-400°C), and rolling reduction ratios to achieve the optimal balance between strength and workability that prevents settling
Solution Approach 2:
The patent creates a composite microstructure consisting of α-phase and β-phase regions through controlled alloying and heat treatment, where the dual-phase structure provides both high strength to prevent settling and adequate ductility for bending workability
2Strength
If cold rolling reduction is increased to improve strength, then strength is improved, but bending workability deteriorates causing cracks
Solution Approach 1:
The patent optimizes the cold rolling reduction ratio parameter to be within 30-70%, which is sufficient to achieve high strength (1000-1500 MPa) while maintaining adequate ductility for bending operations without crack formation
Solution Approach 2:
The patent performs solution treatment before cold rolling to create a homogeneous microstructure and dissolve precipitates, which improves the material's ability to undergo deformation without cracking while maintaining strength after subsequent aging treatment
3Strength
If aging treatment is performed to increase strength, then strength is improved, but spring limit value decreases
Solution Approach 1:
The patent precisely controls the aging treatment parameters including temperature (200-400°C) and time (0.5-10 hours) to achieve optimal precipitation hardening that maximizes 0.2% yield strength while maintaining adequate spring limit value for the intended application
Solution Approach 2:
The patent creates local variations in microstructure through controlled aging, producing fine precipitates distributed throughout the matrix that provide strength through precipitation hardening while maintaining the overall ductility and spring properties of the bulk material
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 titanium-copper foil exhibits excellent strength and bending workability, preventing settling and cracking, making it suitable for use in autofocus camera modules as a conductive spring material.
Implementation Method 1
sequentially performing hot and cold rolling
Implementation Method 2
solution treatment
Implementation Method 3
aging treatment in which a temperature is raised at a rate of 15° C./h or less and kept in a range of 200° C. to 400° C. for 1 to 20 hours
Data Source
AI summary
To provide a high-strength titanium-copper foil that is more suitable as a conductive spring material that can be used in electronic device components such as an autofocus camera module. A titanium copper foil containing Ti in an amount of 2.0 to 4.0 mass %, a remainder being copper and unavoidable impurities, said foil having a 0.2% yield strength of 1000 MPa or more and a spring limit value of 800 MPa or more in both directions parallel and perpendicular to a rolling direction, wherein no cracking occurs at bending radius/foil thickness=2 when a W bending test in conformity with JIS H3130: 2012 is performed at a width of 0.5 mm in a direction perpendicular to the rolling direction.