Titanium Copper Foil Layered Structure Settling Resistance
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Solution Overview
Problem
Conventional titanium copper foils used in autofocus camera modules suffer from low strength and significant settling issues, which hinder their effectiveness as conductive spring materials due to inadequate structural support against electromagnetic forces.
Innovation Solution
A titanium copper alloy with a fine layered structure of Cu and Ti, achieved by adjusting pre-annealing conditions prior to hot rolling, which enhances strength and suppresses settling by maintaining a Ti concentration difference of 3 to 50% by mass and incorporating additional elements like Ag, B, Co, Fe, Mg, Mn, Mo, Ni, P, Si, Cr, and Zr within specific limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium copper foil is used to reduce raw material costs, then cost is reduced, but strength decreases causing settling
Solution Approach 1:
The patent applies parameter changes by controlling the Ti concentration within a specific range (1.5-5.0% by mass) and implementing precise heat treatment parameters (solutionizing at 700-1000°C for 5 seconds to 5 minutes, aging at 300-550°C). These parameter optimizations enable the titanium copper foil to achieve both cost reduction and improved strength, resolving the contradiction between material cost and settling resistance.
Solution Approach 2:
The patent creates a composite material structure by forming a layered structure with Cu-rich and Ti-rich phases through controlled spinodal decomposition during heat treatment. This composite microstructure, characterized by alternating layers at the micrometer scale, provides both the cost benefits of titanium copper and the strength needed to prevent settling in autofocus applications.
2Strength
If heat treatment is applied to increase Ti concentration fluctuation, then strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing a solutionizing treatment before cold rolling to pre-condition the material microstructure. This preliminary heat treatment dissolves precipitates and creates a homogeneous austenitic structure, which facilitates subsequent spinodal decomposition during aging and enables better strength properties without requiring excessively complex multi-stage heat treatment processes.
Solution Approach 2:
The patent implements periodic action through a multi-stage heat treatment process consisting of solutionizing treatment, followed by cold rolling, then aging treatment. This periodic sequence of thermal and mechanical processing steps creates the desired layered microstructure through controlled spinodal decomposition, achieving high strength while maintaining reasonable manufacturing complexity through systematic process organization.
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 high tensile strength of 1100 MPa or more, effectively suppressing settling even in thin foils, making it suitable for high-strength applications like autofocus camera modules with improved resistance to deflection and permanent deformation.
Implementation Method 1
increasing a range of Ti concentration (concentration difference) due to spinodal decomposition and improving a balance between strength and bending workability
Implementation Method 2
adjusting an average crystal grain size by final recrystallization annealing
Implementation Method 3
sequentially carrying out hot rolling and cold rolling, followed by a solutionizing treatment in which a temperature is maintained in a temperature range of from 750 to 1000 °C
Implementation Method 4
cold rolling at a rolling ratio of 0 to 50%, an aging treatment at 300 to 550 °C and finish cold rolling at a rolling ratio of 0 to 30%
Implementation Method 5
an aging treatment at 300 to 550 °C
Data Source
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AI summary
A titanium copper according to the present invention contains from 1.5 to 5.0% by mass of Ti, the balance being of Cu and inevitable impurities, wherein the titanium copper has a layered structure of Cu and Ti where in a Ti concentration curve obtained by analyzing a cross section parallel to a rolling direction along a thickness direction by STEM-EDX., a lower concentration Ti layer having a Ti concentration less than an average value of Ti concentrations in the Ti concentration curve and a higher concentration Ti layer having a Ti concentration equal to or higher than the average value of the Ti concentrations in the Ti concentration curve are alternately present in the thickness direction, and wherein in the cross section parallel to the rolling direction, a Ti concentration difference in the layered structure is 3% by mass or more, the Ti concentration difference being a difference between a maximum value of the Ti concentration in the higher concentration Ti layer and a minimum value of the Ti concentration in the lower concentration Ti layer.