Spring Metal Foil Thickness Uniformity for Precise Etched Leaf Springs
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Solution Overview
Problem
The challenge lies in producing a metal foil for spring members, particularly leaf springs, that maintains uniform thickness to ensure consistent spring load and deflection, as variations in thickness lead to variations in spring width, affecting the performance of autofocus and zoom mechanisms in camera modules within electronic devices.
Innovation Solution
A metal foil with a specific condition where the absolute difference in thickness variance between the rolling direction and width direction is limited to 0.15 μm², ensuring uniformity and reducing variations in spring width, achieved through controlled rolling and annealing processes, allowing for precise etching and improved isotropic etching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-hardness metal is used to satisfy spring load and deflection requirements, then spring performance is improved, but thickness uniformity deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the variance difference of thickness between rolling direction and width direction to be 0.15 μm² or less. This specific parameter control enables the metal foil to maintain both high hardness for spring performance and sufficient thickness uniformity for consistent spring width after etching.
2Volume of moving object
If metal foil thickness is reduced to achieve thin spring members, then device volume is reduced, but thickness control difficulty increases
Solution Approach 1:
The patent controls the variance difference of thickness to be 0.15 μm² or less, enabling precise thickness control even in thinned metal foils. This allows production of thin spring members with consistent dimensions after etching, achieving both volume reduction and manufacturing precision.
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 metal foil that maintains consistent spring performance by minimizing thickness variations, enhancing the durability and reliability of spring members in electronic devices, such as camera modules, by ensuring precise control over spring load and deflection.
Implementation Method 1
A metal foil for a spring member according to an aspect includes a first region on which the spring member is formed. The first region has a square shape with one side being 300 mm. In the first region, an absolute value of a difference value obtained by subtracting variance of a thickness in a width direction orthogonal to a rolling direction from variance of a thickness in the rolling direction is less than or equal to 0.15 μm2.
Implementation Method 2
achieved through controlled rolling and annealing processes, allowing for precise etching and improved isotropic etching characteristics
Implementation Method 3
The leaf spring is formed by wet-etching a metal foil. Variations in the thickness of the metal foil cause variations in the amount of etching, which in turn causes variations in the width of the leaf spring in the thickness direction.
Data Source
AI summary
A metal foil for a spring member includes a first region on which the spring member is formed. The first region has a square shape with one side being 300 mm. In the first region, an absolute value of a difference value obtained by subtracting variance of a thickness in a width direction orthogonal to a rolling direction from variance of a thickness in the rolling direction is less than or equal to 0.15 μm2.