Metal foil for spring members, method for manufacturing metal foil for spring members, and method for manufacturing spring members

Abstract

The present invention provides a metal foil for spring members formed by wet etching of metal foil, a method for manufacturing the metal foil for spring members, and a method for manufacturing the spring member, which enable the suppression of dimensional variations in the spring member. [Solution] The thickness of the metal foil is 100 μm or more and 200 μm or less. The elongation difference ratio in the central region RC in the width direction DW of the metal foil is greater than the elongation difference ratios in the first end region RE1 and the second end region RE2 in the width direction DW. The elongation difference ratio decreases from the central region RC toward the first end region RE1, and also decreases from the central region RC toward the second end region RE2. The maximum value of the elongation difference ratio in the central region RC is 30 × 10⁻¹⁰ -5 The following applies: The maximum value of the difference in elongation in the first end region RE1 and the second end region RE2 is 10 × 10 -5 The following applies:

Description

[Technical Field]

[0001] This disclosure relates to a metal foil for spring members, a method for manufacturing a metal foil for spring members, and a method for manufacturing a spring member. [Background technology]

[0002] Camera modules in electronic devices with cameras, such as tablet devices and smartphones, are equipped with drive mechanisms to enable autofocus and zoom. Two types of drive mechanisms are known: lens drive mechanisms and sensor drive mechanisms. Lens drive mechanisms include a spring member that allows the position of the lens in the optical axis direction to be changed. In contrast, sensor drive mechanisms include a spring member that allows the position of the image sensor in the optical axis direction to be changed (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-059345 [Patent Document 2] Japanese Patent Publication No. 2020-170170 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, leaf springs, which are part of spring components, are required to satisfy a specific spring load or deflection within a limited volume. To meet the requirements for spring load and deflection, spring components must be made from a metal with high hardness. Furthermore, to meet the requirements for spring load and deflection, spring components must have a thickness of a certain magnitude or greater. Therefore, the metal foil used for spring components must also have a thickness of a certain magnitude or greater.

[0005] On the other hand, metal foil for spring components is manufactured by rolling the base material. As mentioned above, metal foil for spring components is required to have a predetermined thickness. Therefore, when manufacturing metal foil, it is difficult to perform rolling a number of times that can eliminate the non-uniformity in the deformation of the base material due to rolling. As a result, for example, the elongation rate of the metal foil differs at each position in the width direction of the metal foil, and as a result, the metal foil may have a wave shape with repeated irregularities in the length direction.

[0006] The first example of a corrugated shape is center elongation, and the second example is edge elongation. In center elongation, the elongation rate at the center is greater than the elongation rate at each end in the width direction of the metal foil. As a result, the metal foil elongates in the width direction and has multiple repeating peaks along the length direction. On the other hand, in edge elongation, the elongation rate at each end is greater than the elongation rate at the center in the width direction of the metal foil. As a result, the metal foil has multiple repeating peaks along the length direction at each end.

[0007] The corrugated shape of the metal foil causes different parts of the foil to have different contact times with the etching solution when a spring component is manufactured from the metal foil by wet etching. For example, if the corrugated shape of the metal foil is elongated in the middle, the velocity of the etching solution flowing through the peaks and valleys between the peaks increases towards the edges in the width direction. In contrast, if the corrugated shape of the metal foil is elongated at the edges, fatigued etching solution tends to accumulate in the valleys between the peaks in the width direction of the metal foil, and the etching solution accumulated in the valleys is less likely to be replaced.

[0008] This non-uniformity in the flow of the etching solution causes dimensional variations in spring components manufactured by wet etching of metal foil. Since dimensional variations tend to increase as the contact time of the metal foil with the etching solution increases, as mentioned above, dimensional variations caused by the corrugated shape of the metal foil tend to become more pronounced in spring components that are required to have a thickness above a certain level. [Means for solving the problem]

[0009] The metal foil for spring members used to solve the above problems is a strip-shaped metal foil used to manufacture spring members by wet etching. The thickness of the metal foil is 100 μm or more and 200 μm or less. The shapes of the metal foil along the length direction at each position in the width direction are different from each other, and each shape is a wave shape with repeating irregularities in the length direction of the metal foil. The length in the length direction on the surface of the metal foil is the surface distance, and the minimum value among the surface distances at each position in the width direction of the metal foil is the minimum surface distance. The ratio of the difference between the surface distances at each position in the width direction of the metal foil and the minimum surface distance to the minimum surface distance is the elongation difference ratio in the length direction. The elongation difference ratio in the central region in the width direction of the metal foil is greater than the elongation difference ratios in the first end region and the second end region in the width direction, and the elongation difference ratio decreases from the central region toward the first end region and from the central region toward the second end region. The maximum value of the elongation difference in the central region is 30 × 10 -5 The following applies: The maximum value of the elongation difference in each of the first and second end regions is 10 × 10 -5 The following applies:

[0010] A method for manufacturing a metal foil for spring members to solve the above problems is a method for manufacturing a metal foil for spring members, which is a strip-shaped metal foil used to manufacture a spring member by wet etching. The method for manufacturing a metal foil for spring members includes rolling a base material to obtain the metal foil. The thickness of the metal foil is 100 μm or more and 200 μm or less. The shapes of the metal foil along the length direction at each position in the width direction are different from each other, and each shape is a wave shape having repeating irregularities in the length direction of the metal foil. The length in the length direction on the surface of the metal foil is the surface distance, and the minimum value among the surface distances at each position in the width direction of the metal foil is the minimum surface distance. The ratio of the difference between the surface distances at each position in the width direction of the metal foil and the minimum surface distance to the minimum surface distance is the elongation difference ratio in the length direction. A method for manufacturing a metal foil for a spring member is such that the elongation difference in the central region in the width direction of the metal foil is greater than the elongation difference in the first and second end regions in the width direction, the elongation difference decreases from the central region toward the first end region, and decreases from the central region toward the second end region, and the maximum value of the elongation difference in the central region is 30 × 10 -5 The following conditions apply, and the maximum value of the elongation difference in the first end region and the second end region is 10 × 10 -5 The following includes rolling the base material.

[0011] A method for manufacturing a spring member for solving the above problems includes forming a resist mask on a strip-shaped metal foil and patterning the metal foil by wet etching using the resist mask. The thickness of the metal foil is 100 μm or more and 200 μm or less. The shape along the length direction of the metal foil at each position in the width direction of the metal foil is different from each other, and each shape is a waveform having unevenness repeating in the length direction of the metal foil. The length in the length direction on the surface of the metal foil is the surface distance, and the minimum value among the surface distances at each position in the width direction of the metal foil is the minimum surface distance. The ratio of the difference between the surface distance and the minimum surface distance at each position in the width direction of the metal foil to the minimum surface distance is the elongation difference rate in the length direction. The elongation difference rate in the central region in the width direction of the metal foil is larger than the elongation difference rates in the first end region and the second end region in the width direction, and the elongation difference rate decreases from the central region toward the first end region and also decreases from the central region toward the second end region. The maximum value of the elongation difference rate in the central region is 30×10 -5 or less. The maximum value of the elongation difference rate in the first end region and the second end region is 10×10 -5 or less.

[0012] According to each of the above configurations, even if the metal foil for the spring member has a waveform such that the elongation difference rate becomes large in the central region in the width direction, it is possible to suppress the flow of the etching solution supplied to the metal foil for the spring member from becoming uneven. As a result, even when manufacturing a spring member by wet etching of a thick metal foil for a spring member having a thickness of 100 μm or more and 200 μm or less, it is possible to suppress variations in the dimensions of the spring member within the plane of the metal foil.

[0013] In the metal foil for the spring member, the central portion in the width direction of the metal foil for the spring member is the central portion in the width direction in the central region, and the length in the width direction of the central region is 30% of the length in the width direction of the metal foil. The first end region includes the first end portion in the width direction of the metal foil for the spring member, and the length in the width direction of the first end region is 20% of the length in the width direction of the metal foil. The second end region includes the second end portion in the width direction of the metal foil for the spring member, and the length in the width direction of the second end region may be 20% of the length in the width direction of the metal foil.

[0014] According to the metal foil for the spring member, an increase in the slope of the elongation difference rate between the central region and each end region can be suppressed compared to the case where the central region is shorter and each end region is longer. Thereby, it is further suppressed that the flow of the etching solution supplied to the metal foil becomes non-uniform.

[0015] In the metal foil for the spring member, the unit length in the width direction is 300 mm, and the average value of the elongation difference rate per unit length is 10×10 -5 It may be as follows. According to the metal foil for the spring member, since the elongation difference rate in the length direction is suppressed over the entire unit length, the flatness of the metal foil is improved.

[0016] In the metal foil for the spring member, the metal foil may include any one selected from the group consisting of a stainless alloy, beryllium copper, nickel tin copper, phosphor bronze, Corson alloy, and titanium copper.

[0017] According to the metal foil for the spring member, since the metal foil for the spring member has high hardness, it is easy for variations in the rolling degree to occur within the metal foil 10, so the effect of the upper limit value of the elongation difference rate in the central region and each end region is more remarkable.

Advantages of the Invention

[0018] According to the metal foil for spring members, the method for manufacturing the metal foil for spring members, and the method for manufacturing a spring member of this disclosure, dimensional variations can be suppressed in a spring member formed by wet etching of a metal foil. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a perspective view showing the structure of a metal foil for a spring member in one embodiment. [Figure 2] Figure 2 is a plan view showing the metal foil used for measurement. [Figure 3] Figure 3 shows a graph illustrating the elongation rate, along with the cross-sectional structure of the metal foil used for measurement. [Figure 4] Figure 4 is a graph illustrating the rate of difference in growth. [Figure 5] Figure 5 is a plan view showing the structure of a spring member in one embodiment of the spring member. [Figure 6] Figure 6 is a process diagram showing one step in one embodiment of a method for manufacturing metal foil for spring components. [Figure 7] Figure 7 is a process diagram showing one step in one embodiment of a method for manufacturing metal foil for spring components. [Figure 8] Figure 8 is a process diagram showing one step in one embodiment of a method for manufacturing a spring member. [Figure 9] Figure 9 is a process diagram showing one step in one embodiment of a method for manufacturing a spring member. [Figure 10] Figure 10 is a process diagram showing one step in one embodiment of a method for manufacturing a spring member. [Figure 11] Figure 11 is a process diagram showing one step in one embodiment of a method for manufacturing a spring member. [Figure 12] Figure 12 is a process diagram showing one step in one embodiment of a method for manufacturing a spring member. [Figure 13] Figure 13 is a plan view showing the structure of the metal foil used for measurement in each example and comparative example, along with its dimensions. [Figure 14]Figure 14 is a graph showing the distribution of elongation ratio in the width direction of the metal foil in Example 1. [Figure 15] Figure 15 is a graph showing the distribution of elongation ratio in the width direction of the metal foil in Example 2. [Figure 16] Figure 16 is a graph showing the distribution of elongation ratios in the width direction of the metal foil in Example 3. [Figure 17] Figure 17 is a graph showing the distribution of elongation ratios in the width direction for the metal foil of Comparative Example 1. [Figure 18] Figure 18 is a graph showing the distribution of elongation ratios in the width direction for the metal foil of Comparative Example 2. [Figure 19] Figure 19 is a table showing the calculated elongation rate for each metal foil, broken down by position in the width direction. [Figure 20] Figure 20 is a table showing the results of measuring the width variation in spring members manufactured using each metal foil. [Modes for carrying out the invention]

[0020] Referring to Figures 1 to 20, a metal foil for spring members, a method for manufacturing the metal foil for spring members, and an embodiment of the method for manufacturing the spring member will be described.

[0021] [Metal foil for spring components] Referring to Figure 1, the metal foil for the spring component will be explained. As shown in Figure 1, the metal foil 10 for spring members (hereinafter also referred to as metal foil 10) is used to manufacture spring members by wet etching. The metal foil 10 is a rolled material formed from a metal having a hardness high enough to achieve the required spring load or deflection for the spring member 20 (see Figure 5). The metal foil 10 has a strip shape. The metal foil 10 has a shape that follows a two-dimensional plane defined by the length direction DL and the width direction DW. In the metal foil 10, the length in the length direction DL is significantly larger than the length in the width direction DW.

[0022] The metal foil 10 comprises a surface 10F and a back surface 10R opposite to the surface 10F. The thickness T of the metal foil 10 is the distance between the surface 10F and the back surface 10R. The thickness of the metal foil 10 is within the range of 100 μm to 200 μm. The thickness T of the metal foil 10 has uniformity such that the ratio of the difference between the maximum and minimum values ​​of the thickness T of the metal foil 10 to the average value of the thickness T of the metal foil 10 is 3% or less.

[0023] The metal foil 10 includes a plurality of peaks 10A and valleys 10B located between the peaks 10A. Each peak 10A has a shape that extends along the width direction DW. The plurality of peaks 10A are spaced apart along the length direction DL. The peaks 10A and valleys 10B of the metal foil 10 are formed by the difference in elongation rates of the metal foil 10 at each position in the width direction DW.

[0024] As described above, the metal foil 10 is made of a metal having a hardness high enough to achieve the required spring load or deflection for the spring member 20 manufactured using the metal foil 10. The metal foil 10 may be made of, for example, a stainless steel alloy or a copper alloy. The stainless steel alloy may be, for example, a stainless steel alloy specified in JIS G 4313:2011 "Stainless steel strips for springs". The copper alloy may be, for example, a copper alloy specified in JIS H 3130:2018 "Sheets and strips of beryllium copper, titanium copper, phosphor bronze, nickel-tin copper and nickel silver for springs".

[0025] The metal foil 10 preferably includes one selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium copper. This allows the metal foil 10 to have high hardness, thereby increasing the durability of the spring member formed from the metal foil 10.

[0026] The Vickers hardness of the metal foil 10 may be, for example, HV150 or more, HV200 or more, or HV250 or more. The Vickers hardness is a value measured by a method compliant with JIS Z 2244:2009 "Vickers hardness test - Test method". The tensile strength of the metal foil 10 may be, for example, 600 N / mm 2 or more, 700 N / mm 2 or more, 800 N / mm 2 or more. The tensile strength is a value measured by a method compliant with JIS Z 2241:2011 "Tensile test method for metallic materials".

[0027] [Elongation difference rate] Referring to FIGS. 2 to 4, the elongation difference rate will be described. In a state where the metal foil 10 is placed on a horizontal plane, the position of the surface of the metal foil 10 with respect to the horizontal plane, that is, the height is the surface position.

[0028] As shown in FIG. 2, in the measurement of the surface position, first, the metal foil 10 is cut by a slitting process so that the dimension in the width direction DW of the rolled metal foil 10 becomes the width W, whereby a metal foil 10 having a strip shape is obtained. The obtained metal foil 10 is wound up in a roll shape. Next, a slitting process is performed in which the metal foil 10 is cut in the entire width direction DW, that is, the full width, whereby a measurement foil 10M is cut out as a part in the length direction DL of the metal foil 10. The width W in the width direction DW of the measurement foil 10M is equal to the dimension in the width direction DW of the metal foil 10. Next, for the surface 10MS of the measurement foil 10M, the surface position at each position in the length direction DL is measured at predetermined intervals in the width direction DW. The range in which the surface position is measured is the measurement range ZL.

[0029] The measurement range ZL excludes the non-measurement range ZE, which is the lengthwise end DL of the measurement foil 10M. The measurement range ZL also excludes the non-measurement range (not shown), which is the widthwise end DW of the measurement foil 10M. The slitting process that cuts the metal foil 10 may form a new wave shape on the measurement foil 10M that is different from the wave shape of the metal foil 10. The length of each non-measurement range ZE in the lengthwise DL is the range in which such a new wave shape may be formed and is excluded from the measurement of the surface position. The length of each non-measurement range ZE in the lengthwise DL is, for example, 100 mm. In the widthwise direction as well, in order to exclude the new wave shape formed by the slitting process, the length of the non-measurement range in the widthwise DW is, for example, 10 mm from the end of the widthwise DW.

[0030] Figure 3 is a graph showing an example of the surface position at various points along the length DL of the measuring foil 10M. Figure 3 shows the surface position of the measuring foil 10M along with the cross-sectional structure in a section including the length DL of the measuring foil 10M. Note that in Figure 3, an example is shown of a portion of the width DW that has three waves in the length DL.

[0031] As shown in Figure 3, the positions in the length direction DL where the height is measured are spaced apart to allow for the reproduction of the corrugated surface of the metal foil 10. For example, the positions in the length direction DL where the height is measured are spaced apart at equal intervals of 1 mm to 20 mm. The length of the broken line LW connecting the heights of each position in the length direction DL is calculated as the surface distance La. The elongation difference ratio of the metal foil 10 in the length direction DL is determined by the following equation 1. That is, if the minimum value of the surface distance La at each position in the width direction DW of the metal foil 10 is taken as the minimum surface distance Lm, then the elongation difference ratio is the ratio of the difference between each surface distance La and the minimum surface distance Lm to the minimum surface distance Lm. Elongation difference = (La - Lm) / Lm … (Equation 1)

[0032] Figure 4 shows an example of the difference in elongation ratio in the length direction DL at various positions in the width direction DW of the metal foil 10. As shown in Figure 4, the elongation rate of the metal foil 10 is maximum in the central region RC in the width direction DW. The elongation rate of the metal foil 10 decreases from the central region RC toward the first end region RE1 in the width direction DW, and also decreases from the central region RC toward the second end region RE2 in the width direction DW.

[0033] The central portion PC of the metal foil 10 in the width direction DW is the central portion of the width direction DW in the central region RC. The length of the central region RC in the width direction DW is 30% of the length of the metal foil 10 in the width direction DW. The first end region RE1 includes the first end E1 in the width direction DW of the metal foil 10, and the length of the first end region RE1 in the width direction DW is 20% of the length of the metal foil 10 in the width direction DW. The second end region RE2 includes the second end E2 in the width direction DW of the metal foil 10, and the length of the second end region RE2 in the width direction DW is 20% of the length of the metal foil 10 in the width direction DW.

[0034] The metal foil 10 includes a first intermediate region RI1 located between the first end region RE1 and the central region RC in the width direction DW, and a second intermediate region RI2 located between the second end region RE2 and the central region RC. The elongation rate in the first intermediate region RI1 decreases from the central region RC toward the first end region RE1. The elongation rate in the second intermediate region RI2 decreases from the central region RC toward the second end region RE2.

[0035] The metal foil 10 satisfies the following six conditions. (Condition 1) The thickness T of the metal foil 10 is between 100 μm and 200 μm. (Condition 2) The difference in elongation rate in the central region RC in the width direction DW of the metal foil 10 is greater than the difference in elongation rate in the first end region RE1 and the second end region RE2 in the width direction DW. (Condition 3) The difference in elongation decreases from the central region RC towards the first end region RE1. (Condition 4) The rate of elongation decreases from the central region RC towards the second end region RE2. (Condition 5) The maximum value of the elongation difference in the central RC region is 30 × 10 -5 The following applies:

[0036] (Condition 6) The maximum value of the difference in elongation in the first end region RE1 and the second end region RE2 is 10 × 10 -5 The following applies:

[0037] In the metal foil 10 that satisfies conditions 2, 3, and 4, the elongation rate due to rolling is greater in the central region RC than in the first end region RE1 and the second end region RE2. Therefore, the central region RC is convex relative to the end regions RE1 and RE2 by the amount of the difference in elongation rate between the central region RC and each end region RE1 and RE2, i.e., it becomes a peak 10A. As a result, the etching solution supplied to the metal foil 10 during wet etching flows from the central region RC towards each end region RE1 and RE2 according to the difference in surface position between the central region RC and each end region RE1 and RE2, and further flows out of the metal foil 10 from each end region RE1 and RE2. As a result, the etching solution does not easily remain in the central region RC, and in each end region RE1 and RE2, the etching solution flows with increased momentum due to the difference in surface position.

[0038] This flow occurs not only in the peaks 10A caused by the difference in elongation rates, but also in the valleys 10B located between the peaks 10A. In addition, in the valleys 10B, the etching solution flows from the peaks 10A to the valleys 10B along the length direction DL, according to the difference in surface position between the peaks 10A and the valleys 10B, resulting in a similar flow of etching solution as in the peaks 10A.

[0039] As a result, in the spring members 20 that are surfaced on each end region RE1, RE2 of the metal foil 10, etching progresses easily in the portion corresponding to the second spring portion 23B (see Figure 5) that extends along the length direction DL, while etching does not progress easily in the portion corresponding to the first spring portion 23A (see Figure 5) that extends along the width direction DW. This results in variations in the amount of etching between the spring portions 23A and 23B of a single spring member 20.

[0040] In this regard, since the metal foil 10 of this disclosure satisfies condition 5, the surface position of the central region RC is prevented from becoming excessively high. As a result, the etching solution supplied to the central region RC is prevented from flowing vigorously from the central region RC towards each end region RE1 and RE2 according to the difference in elongation rate. Furthermore, since the metal foil 10 satisfies conditions 5 and 6 simultaneously, the difference in surface position between the central region RC and each end region RE1 and RE2 is suppressed. As a result, the flow of the etching solution according to the difference in surface position at each position of the metal foil 10 is prevented.

[0041] Moreover, since the metal foil 10 of this disclosure satisfies condition 1, it is possible to suppress dimensional variations in the spring member 20 manufactured by etching the metal foil 10, even in a metal foil 10 that is thick enough to easily cause unevenness in surface positioning and therefore requires a longer etching time.

[0042] Thus, with the metal foil 10 of this disclosure, even if the metal foil 10 has a wave shape such that the elongation difference is large in the central region RC in the width direction DW, the non-uniformity of the etching solution flow supplied to the metal foil 10 is suppressed. As a result, even when a spring member 20 is manufactured by wet etching of a thick metal foil 10 having a thickness of 100 μm or more and 200 μm or less, variations in the dimensions of the spring member within the plane of the metal foil 10 are suppressed.

[0043] Furthermore, the central region RC and each end region RE1, RE2 are set within the range described above in the width direction DW. Therefore, compared to the case where the central region RC is shorter and each end region RE1, RE2 is longer, the slope of the elongation difference between the central region RC and each end region RE1, RE2 is suppressed to be larger. This further suppresses the non-uniformity of the etching solution flow supplied to the metal foil 10.

[0044] When the spring member 20 is manufactured from the metal foil 10, the metal foil 10 is supplied with liquids other than the etching solution, such as a developer, a stripping solution, and a cleaning solution. The developer is a liquid for developing the resist layer located on the surface of the metal foil 10. The stripping solution is a liquid for stripping the resist layer remaining on the surface of the metal foil 10 after etching. The cleaning solutions include a cleaning solution for removing the developer from the surface, a cleaning solution for removing the etching solution from the surface, a cleaning solution for removing the stripping solution from the surface, and a cleaning solution for removing the stripping solution from the surface. With the metal foil 10 of this disclosure, it is also possible to improve the uniformity of processing with these liquids, not just the etching solution.

[0045] Furthermore, the metal foil 10 of this disclosure makes it possible to ensure good adhesion between the resist layer and the metal foil 10, as well as accuracy in exposure to the resist layer. In addition, the metal foil 10 of this disclosure makes it possible to suppress misalignment when the metal foil 10 is transported in a roll-to-roll manner, which, combined with the fact that unevenness in the liquid flow is less likely to occur, makes it possible to further improve the uniformity of the processing.

[0046] Thus, the metal foil 10 that satisfies conditions 1 to 6, and the effects obtained by said metal foil 10, can only be derived by recognizing the challenges in surface processing using liquids, which arise from the difference in elongation rate in the central region RC and the difference in elongation rates in each end region RE1, RE2.

[0047] The metal foil 10 may also satisfy the following condition 7. (Condition 7) The unit length in the width direction DW is 300 mm, and the average value of the elongation rate per unit length is 10 × 10 -5 The following applies:

[0048] When the metal foil 10 satisfies condition 7, the elongation rate in the length direction DL is suppressed over the entire unit length, thus improving the flatness of the metal foil 10. Furthermore, when the unit length in the width direction DW coincides with the total length of the width direction DW in the metal foil 10, the average value over the entire width direction of the metal foil 10, including the central region RC, is 10 × 10 -5Therefore, the flatness of the metal foil 10 is improved.

[0049] The metal foil 10 may also satisfy at least one of the following conditions 8 and 9. That is, the metal foil 10 may satisfy only one of conditions 8 and 9, or it may satisfy both conditions 8 and 9.

[0050] (Condition 8) In each of the first end region RE1 and the second end region RE2, the minimum value of the elongation difference is 1.0 × 10⁻⁶. -5 That's all. (Condition 9) In the central RC region, the minimum value of the elongation difference is 5.0 × 10 -5 That's all.

[0051] If the metal foil 10 satisfies at least one of conditions 8 and 9, it is possible to reduce the burden on the manufacturing of the metal foil 10 compared to the case where the minimum value of the elongation difference of the metal foil 10 is smaller.

[0052] [Spring component] The spring member 20 will be described with reference to Figure 5. Figure 5 schematically shows the planar structure of the spring member 20 as viewed from a viewpoint opposite to the plane in which the spring member 20 extends.

[0053] As shown in Figure 5, the spring member 20 comprises an outer frame portion 21, an inner frame portion 22, and a spring portion 23. In the example shown in Figure 5, the outer frame portion 21 has an octagonal shape, and the inner frame portion 22 has a circular shape. The spring portion 23 has a folded shape. The outer shapes of the outer frame portion 21 and the inner frame portion 22 may be changed according to the shapes of other components of the drive mechanism of the camera module on which the spring member 20 is mounted, i.e., components other than the spring member 20. The inner frame portion 22 is located within the area defined by the outer frame portion 21. The spring portion 23 connects the inner frame portion 22 to the outer frame portion 21.

[0054] In the example shown in Figure 5, the spring member 20 comprises four spring portions 23. Of the four spring portions 23, two spring portions 23 sandwich the inner frame portion 22 in the longitudinal direction DL, and the other two spring members 20 sandwich the inner frame portion 22 in the width direction DW, such that the spring members 20 are surfaced on the metal foil 10. Of the four spring portions 23, the spring portion 23 that sandwiches the inner frame portion 22 in the longitudinal direction DL is the first spring portion 23A. Of the four spring portions 23, the spring portion 23 that sandwiches the inner frame portion 22 in the width direction DW is the second spring portion 23B. Each first spring portion 23A includes a plurality of leaf springs 23A1 extending along the width direction DW. Each second spring portion 23B includes a plurality of leaf springs 23B1 extending along the longitudinal direction DL.

[0055] In the leaf spring 23A1 included in the first spring section 23A, the length of the leaf spring 23A1 along the longitudinal direction DL is the spring width SWA of the leaf spring 23A1. In the leaf spring 23B1 included in the second spring section 23B, the length of the leaf spring 23B1 along the width direction DW is the spring width SWB of the leaf spring 23B1.

[0056] The drive mechanism of the lens drive system may include one spring member 20 or a pair of spring members 20. When the drive mechanism includes one spring member 20, the spring member 20 and the lens are spaced apart in the optical axis direction of the lens. When the drive mechanism includes a pair of spring members 20, the pair of spring members 20 are arranged to sandwich the lens in the optical axis direction of the lens. By changing the position of the inner frame portion 22 connected to each outer frame portion 21 in the optical axis direction, the position of the lens in the optical axis direction of the lens changes. This makes it possible to correct camera shake with the drive mechanism of the lens drive system.

[0057] The sensor-driven drive mechanism may comprise one spring member 20 or a pair of spring members 20. When the drive mechanism comprises one spring member 20, the spring member 20 and the image sensor are spaced apart in the optical axis direction of the lens. When the drive mechanism comprises a pair of spring members 20, the pair of spring members 20 are arranged to sandwich the image sensor in the optical axis direction of the lens. By changing the position of the inner frame portion 22 connected to each outer frame portion 21 in the optical axis direction, the position of the image sensor in the optical axis direction of the lens changes. This makes it possible to correct camera shake using the sensor-driven drive mechanism.

[0058] The camera module includes a drive mechanism that incorporates the spring member 20 described above. The electronic device on which the camera module is mounted may be, for example, a mobile phone, a smartphone, a tablet, or a notebook personal computer.

[0059] [Method for manufacturing metal foil for spring components] The manufacturing method of the metal foil 10 will be described with reference to Figures 6 and 7. The method for manufacturing the metal foil 10 includes obtaining the metal foil 10 by rolling a base material. Rolling the base material involves rolling the base material so that the metal foil 10 satisfies the conditions 1 to 6 described above. The method for manufacturing the metal foil 10 will be described in more detail below with reference to the drawings.

[0060] Figures 6 and 7 schematically show the process of rolling the base material to form the metal foil 10. As shown in Figure 6, when the metal foil 10 is manufactured, first, a base material BM1 having a strip shape extending along the rolling direction DR is prepared. The rolling direction DR is parallel to the length direction DL of the metal foil 10. Next, the base material BM1 is conveyed along the conveying direction toward a rolling mill RE equipped with a pair of rolling rolls RL1 and RL2, so that the rolling direction DR of the base material BM1 and the conveying direction of the base material BM1 are parallel.

[0061] When the base material BM1 reaches between the pair of rolling rolls RL1 and RL2, the base material BM1 is rolled by the pair of rolling rolls RL1 and RL2. This reduces the thickness of the base material BM1 and stretches it along the conveying direction, thereby obtaining rolled material BM2. The rolled material BM2 is wound onto the core C. Alternatively, the rolled material BM2 may be handled in a strip-like state without being wound onto the core C. The thickness of the rolled material BM2 is within the range of 100 μm to 200 μm.

[0062] As shown in Figure 7, in order to remove the residual stress accumulated inside the rolled material BM2 formed by rolling the base material BM1, the rolled material BM2 is annealed using an annealing apparatus AE. This yields metal foil 10. Since the annealing of the rolled material BM2 is performed while pulling the rolled material BM2 along the conveying direction, metal foil 10 can be obtained with reduced residual stress compared to the rolled material BM2 before annealing.

[0063] The material forming the base material BM1 may include any of the following selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium copper, as described above. Since these metals have high hardness, in other words, they are less ductile than metals with lower hardness, i.e., softer metals, so variations in the degree of rolling are likely to occur within the base material BM1. Furthermore, variations in the degree of rolling are also likely to occur between multiple base material BM1. Thus, because the metal foil 10 has high hardness, and this makes it easy for variations in the degree of rolling to occur within the metal foil 10, the effect of the upper limit of the elongation difference ratio in the central region RC and each end region RE1, RE2 is more pronounced.

[0064] The method for manufacturing the metal foil 10 may include a step of selecting the metal foil 10 from the rolled material after annealing. In this case, after preparing multiple rolled materials obtained through rolling and annealing, the surface distance in the length direction DL is measured at each position in the width direction DW for each rolled material. Then, the elongation difference ratio of the length direction DL at each position in the width direction DW is calculated using the measured surface distance. Next, the rolled material that satisfies the above-described conditions 1 to 6 is selected from the multiple rolled materials as the metal foil 10. The selected metal foil 10 is used in the manufacture of the spring member 20.

[0065] Thus, the sorting process includes conditions 1 to 6 as conditions for sorting the metal foil 10. The sorting process may also include at least one of conditions 7 to 9 as conditions for sorting the metal foil 10. In other words, the sorting process may include only one of conditions 7 to 9, or two or more, as conditions for sorting the metal foil 10.

[0066] In the manufacture of the metal foil 10, the rotational speed of the rolling rolls RL1 and RL2, the pressing force between the rolling rolls RL1 and RL2, the temperature of the rolling rolls RL1 and RL2, the number of rolling rolls RL1 and RL2, and the annealing temperature of the rolling material BM2 are set so that conditions 1 to 6 are satisfied. Alternatively, the rolling mill RE may be equipped with, for example, a pair of backup rolls, intermediate rolls, and work rolls which are the rolling rolls RL1 and RL2. The work rolls may also be crown rolls. In this case, the crown amount of the work rolls, the diameter of the work rolls, the shift amount of the work rolls with respect to the width direction DW, and the shift amount of the intermediate rolls with respect to the width direction DW may be set so that conditions 1 to 6 are satisfied.

[0067] [Method for manufacturing spring components] The manufacturing method of the spring member 20 will be explained with reference to Figures 8 to 12. The manufacturing method for the spring member 20 includes forming a resist mask on a strip-shaped metal foil 10, and patterning the metal foil 10 by wet etching using the resist mask. The metal foil 10 satisfies conditions 1 to 6 described above. The manufacturing method for the spring member 20 will now be described with reference to the drawings.

[0068] As shown in Figure 8, when manufacturing the spring member 20, first a first resist layer PR1 is formed on the surface 10F of the metal foil 10, and a second resist layer PR2 is formed on the back surface 10R. In the example explained using Figures 8 to 12, each resist layer PR1 and PR2 is formed from a positive-type photoresist, but each resist layer PR1 and PR2 may be formed from a negative-type photoresist.

[0069] Next, as shown in Figure 9, the first photomask PM1 is placed on the first resist layer PR1, and the second photomask PM2 is placed on the second resist layer PR2. Then, the first resist layer PR1 is exposed using the first photomask PM1, and the second resist layer PR2 is exposed using the second photomask PM2.

[0070] As shown in Figure 10, the exposed resist layers PR1 and PR2 are developed to form the first resist mask RM1 from the first resist layer PR1 and the second resist mask RM2 from the second resist layer PR2.

[0071] As shown in Figure 11, the metal foil 10 is wet-etched using resist masks RM1 and RM2. During this process, the metal foil 10 is etched from both the front surface 10F and the back surface 10R. This creates through-holes in the metal foil 10 that penetrate along the thickness direction, resulting in the formation of an outer frame portion 21, an inner frame portion 22 separated from the outer frame portion 21, and a spring portion 23 connecting the inner frame portion 22 to the outer frame portion 21.

[0072] In this case, since the metal foil 10 satisfies conditions 1 to 6, dimensional variations are suppressed in the leaf springs 23A1 and 23B1 included in the spring portion 23 of the spring member 20. Furthermore, since the metal foil 10 satisfies conditions 1 to 6, it is possible to obtain a spring member 20 in which dimensional variations are suppressed within a predetermined range without changing the wet etching conditions according to the elongation rate of the metal foil 10. Therefore, in the manufacturing of the spring member 20, it is not necessary to change the wet etching conditions according to the elongation rate, and it is possible to eliminate errors in the combination of elongation rate variations and wet etching conditions. The wet etching conditions include, for example, the amount of spray and the arrangement of the spray on the metal foil 10 when performing spray etching.

[0073] As shown in Figure 12, after removing the resist masks RM1 and RM2 from the etched metal foil 10, the spring member 20 can be obtained by cutting out the etching pattern corresponding to the spring member 20 from the etched metal foil 10.

[0074] [Examples] Examples and comparative examples will be described with reference to Figures 13 to 20. [Example 1] First, a base material BM1 made of titanium copper (C1990, JIS H 3130:2018) was subjected to a rolling process to form a rolled material BM2. Next, a slitting process was performed to cut the rolled material BM2 so that a desired size could be obtained in the width direction DW, thereby adjusting the length of the width direction DW in the rolled material BM2. Subsequently, the rolled material BM2 was subjected to an annealing process, thereby obtaining the metal foil 10 of Example 1, which had a width direction DW length of 300 mm and a thickness of 150 μm.

[0075] Next, as shown in Figure 13, a measuring foil 10M of Example 1, with a length DL of 500 mm, was cut from the metal foil 10 of Example 1. Subsequently, the surface distance DL in the length direction of the cut measuring foil 10M was measured, and then the elongation difference ratio was calculated using the measured surface distance. The following conditions were used for measuring the surface distance.

[0076] Measurement device: Nikon Corporation CNC image measurement system VMR-6555 Measurement range ZL length direction DL length: 300 mm Length in the non-measurement range ZE (length in the direction of DL): 100 mm Measurement interval in the length direction DL: 1 mm Measurement interval in the width direction (DW): 15 mm

[0077] The calculation results for the elongation rate in Example 1 are shown in Figures 14 and 19. Furthermore, the average value of the elongation rate per unit length in the width direction DW was 7.5 × 10⁻⁶. -5 That was the case.

[0078] [Examples 2, 3 and Comparative Examples 1, 2] In Example 2, the amount of work roll shift in the width direction DW was changed compared to Example 1, and the reduction ratio was increased compared to Example 1 to obtain the metal foil 10 of Example 2 with a thickness of 120 μm. In Example 3, the amount of work roll shift in the width direction DW was changed compared to Examples 1 and 2, and the reduction ratio was decreased compared to Example 1 to obtain the metal foil 10 of Example 3 with a thickness of 200 μm. In Comparative Example 1, the metal foil 10 of Comparative Example 1 with a thickness of 150 μm was obtained by using a work roll with a larger crown amount than the work roll used to manufacture the metal foil 10 of Example 3. In Comparative Example 2, the metal foil 10 of Comparative Example 2 with a thickness of 150 μm was obtained by using a work roll with a larger crown amount than the work roll used to manufacture the metal foil 10 of Comparative Example 1.

[0079] The calculation results for the elongation rate in Example 2 are shown in Figures 15 and 19, and the average value of the elongation rate per unit length in the width direction DW is 11.7 × 10⁻⁶. -5 The calculation results for the elongation rate in Example 3 are shown in Figures 16 and 19, and the average value of the elongation rate per unit length in the width direction DW was 8.1 × 10⁻⁶. -5 The calculation results for the elongation rate in Comparative Example 1 are shown in Figures 17 and 19, and the average value of the elongation rate per unit length in the width direction DW was 19.9 × 10⁻⁶. -5 The calculation results for the elongation rate in Comparative Example 2 are shown in Figures 18 and 19, and the average value of the elongation rate per unit length in the width direction DW was 68.8 × 10⁻⁶. -5 That was the case.

[0080] [Etching of metal foil] For each measuring foil 10M, resist masks RM1 and RM2, each having multiple openings corresponding to the shape of the spring member 20, were formed on the front and back surfaces. Then, the measuring foil 10M was wet-etched from both the front and back surfaces using the two resist masks RM1 and RM2. On the measuring foil 10M, unit regions corresponding to one spring member 20 and having a 20 mm square shape were arranged in a grid pattern at equal intervals in both the length direction DL and the width direction DW. Therefore, each resist mask RM1 and RM2 also had unit patterns corresponding to the shape of one spring member 20 arranged in a grid pattern at equal intervals in both the length direction DL and the width direction DW.

[0081] In the unit pattern, in the portion of the spring member 20 that forms the folded spring portion 23, the opening width of the resist masks RM1 and RM2 corresponding to the gap between the leaf springs 23A1 and 23B1 is set to 100 μm, and the pitch between adjacent leaf springs 23A1 and 23B1 is set to 200 μm. Here, the pitch between adjacent leaf springs 23A1 and 23B1 refers to the distance between the center lines set for each leaf spring 23A1 and 23B1 in the etching pattern design, where the leaf springs are parallel to each other and are adjacent.

[0082] Furthermore, multiple unit patterns were formed on each resist mask RM1 and RM2 such that, in a plan view facing the surface 10MS of the measurement foil 10M, the entirety of one unit pattern on resist mask RM1 located on the surface 10MS of the measurement foil 10M overlaps with the entirety of one unit pattern on resist mask RM2 located on the back surface of the measurement foil 10M.

[0083] Using these resist masks RM1 and RM2, multiple etching patterns corresponding to the shape of the spring member 20 were formed on the measurement foil 10M. In the etching patterns, the design values ​​of the spring widths SWA and SWB in a plan view of the spring portion 23 were set to 30 μm.

[0084] [Method for measuring spring width] The spring portion 23 of the spring member 20 contained in each etched measuring foil 10M was embedded in synthetic resin. Then, by cutting the embedded spring portion 23 using a microtome, the cross-section of the spring portion 23 in a plane perpendicular to the direction in which the leaf springs 23A1 and 23B1 contained within the spring portion 23 extend was exposed. For each spring portion 23, the cross-section in a plane perpendicular to the direction in which the leaf spring 23A1 extends and the cross-section in a plane perpendicular to the direction in which the leaf spring 23B1 extends were exposed.

[0085] On the surface 10MS of the measurement foil 10M, the spring width SWA of the leaf spring 23A1 and the spring width SWB of the leaf spring 23B1 were measured for each etching pattern. For each region RC, RE1, and RE2, the variation was calculated by subtracting the minimum value from the maximum value among all measured values ​​of spring width SWA and spring width SWB. In addition, for each region RC, RE1, and RE2, the difference value was calculated by subtracting the spring width SWB from the spring width SWA for each unit pattern, and the directional difference of spring width was calculated as the average of the difference values ​​in each region RC, RE1, and RE2.

[0086] When measuring the spring widths SWA and SWB of the spring portion 23, a digital microscope (VHX-7000, manufactured by Keyence Corporation) was used, and the magnification of the objective lens on the digital microscope was set to 200x.

[0087] [Evaluation Results] [Growth rate] As shown in Figures 14 and 19, in Example 1, the maximum value of the elongation difference in the central region RC is 24.9 × 10⁻⁶. -5 Therefore, the maximum value of the elongation rate in the first end region RE1 is 4.2 × 10⁻⁶. -5 Therefore, the maximum value of the elongation difference in the second end region RE2 is 2.8 × 10⁻⁶. -5 It was confirmed that... As shown in Figures 15 and 19, in Example 2, the maximum value of the elongation rate in the central region RC was 29.3 × 10 -5 Therefore, the maximum value of the elongation difference in the first end region RE1 is 7.5 × 10⁻⁶. -5 Therefore, the maximum value of the elongation difference in the second end region RE2 is 9.7 × 10⁻⁶. -5 It was confirmed that... As shown in Figures 16 and 19, in Example 3, the maximum value of the elongation rate in the central region RC was 18.7 × 10 -5 Therefore, the maximum value of the elongation rate in the first end region RE1 is 3.8 × 10⁻⁶. -5 Therefore, the maximum value of the elongation difference in the second end region RE2 is 3.2 × 10⁻⁶. -5 It was confirmed that this was the case.

[0088] As shown in Figures 17 and 19, in Comparative Example 1, the maximum value of the elongation difference in the central region RC was 46.8 × 10⁻⁶. -5 Therefore, the maximum value of the elongation rate in the first end region RE1 is 10.1 × 10 -5 Therefore, the maximum value of the elongation difference in the second end region RE2 is 4.2 × 10⁻⁶. -5 It was found that... As shown in Figures 18 and 19, in Comparative Example 2, the maximum value of the elongation difference in the central region RC was 149.9 × 10⁻⁶. -5 Therefore, the maximum value of the elongation rate in the first end region RE1 is 11.9 × 10⁻⁶. -5 Therefore, the maximum value of the elongation rate in the second end region RE2 is 24.4 × 10⁻⁶. -5 It was confirmed that this was the case.

[0089] [Spring width] As shown in Figure 20, the variation in spring width SWA and SWB was greatest in the central region RC for all measurement foils 10M, and it was observed that the variation in the central region RC in Comparative Examples 1 and 2 was greater than the variation in the central region RC in Examples 1 to 3.

[0090] These results suggest that because the central region RC includes peaks 10A due to differences in elongation rates, the amount of etching solution supplied to each position in the central region RC tends to vary, resulting in variations in the spring width, which is the result of etching. Furthermore, in Comparative Examples 1 and 2, the maximum value of the elongation rate in the central region RC is larger than in Examples 1 to 3, and therefore the slope of the elongation rate is also larger. As a result, the amount of etching solution supplied to each position in the central region RC tends to vary even more, and consequently, the spring width tends to vary even more. In other words, in Examples 1 to 3, the maximum value of the elongation rate in the central region RC is smaller than in Comparative Examples 1 and 2. As a result, the slope of the elongation rate is also smaller, making it less likely for the amount of etching solution supplied to each position in the central region RC to vary, and consequently, the spring width tends to vary less.

[0091] On the other hand, in Examples 1 to 3, it was observed that the directional difference of the spring width was approximately the same regardless of the position in the width direction DW. In contrast, in Comparative Examples 1 and 2, it was observed that the difference between the directional difference of the spring width in the central region RC and the directional difference of the spring width in each end region RE1 and RE2 was large, and the directional difference of the spring width in the end regions RE1 and RE2 itself was also large.

[0092] These results suggest that in Examples 1 to 3, the maximum value of the elongation rate in the central region RC was small, and the difference between the elongation rate in the central region RC and the elongation rates in each end region RE1 and RE2 was also small, thus suppressing the directional difference in spring width.

[0093] As described above, according to one embodiment of the metal foil for spring members, the method for manufacturing the metal foil for spring members, and the method for manufacturing the spring member, the following effects can be obtained. (1) Even if the metal foil 10 has a wave shape such that the difference in elongation is large in the central region RC in the width direction DW, the flow of the etching solution supplied to the metal foil 10 is suppressed to be non-uniform. As a result, even when the spring member 20 is manufactured by wet etching of a thick metal foil 10 having a thickness of 100 μm or more and 200 μm or less, variations in the dimensions of the spring member within the plane of the metal foil 10 are suppressed.

[0094] (2) When the central region RC and each end region RE1, RE2 are set within the range described above in the width direction DW, the slope of the elongation difference between the central region RC and each end region RE1, RE2 is suppressed to be larger compared to the case where the central region RC is shorter and each end region RE1, RE2 is longer. This further suppresses the non-uniformity of the etching solution flow supplied to the metal foil 10.

[0095] (3) The average value of the elongation rate per unit length in the width direction DW is 1 × 10 -5 If the following conditions are met, the elongation difference in the longitudinal direction DL is suppressed over the entire unit length, thereby improving the flatness of the metal foil 10.

[0096] (4) When the metal foil 10 includes any of the materials selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium copper, the metal foil for the spring member has high hardness. As a result, variations in the degree of rolling tend to occur within the metal foil 10, and the effect of the upper limit of the elongation difference in the central region RC and each end region RE1, RE2 becomes more pronounced.

[0097] The above-described embodiment can be implemented with the following modifications. [Method of manufacturing metal foil] • In the rolling process, it is also possible to use a rolling mill equipped with multiple pairs of rolling rolls and to roll BM1 using multiple pairs of rolling rolls. Using multiple pairs of rolling rolls allows for greater flexibility in the control parameters required to satisfy conditions 1 to 6.

[0098] • In the annealing process, instead of annealing the rolled material BM2 while pulling it in the longitudinal direction DL, it is also possible to anneal the rolled material BM2 wound around the core C. However, when annealing the rolled material BM2, the metal foil 10 may develop a warp depending on the roll diameter. Therefore, depending on the material of the metal foil 10 and the size of the roll when wound around the core C, it is preferable to anneal the rolled material BM2 while pulling it.

[0099] It is also possible to manufacture the metal foil 10 by repeatedly alternating between the rolling process and the annealing process multiple times. After annealing the rolled material BM2, the rolled material BM2 may be cut so that its dimension in the width direction DW becomes width W. This also makes it possible to obtain a metal foil 10 having width W in the width direction DW. [Explanation of Symbols]

[0100] 10…Metal foil for spring components 20... Spring component 21... Outer frame 22...Inner frame section 23... Spring part E1...first end E2…Second end PC…Central part RC…Central area RE1...first end area RE2…Second end area

Claims

1. A metal foil for spring members, which is a strip-shaped metal foil used to manufacture spring members by wet etching, The thickness of the metal foil is 100 μm or more and 200 μm or less. The shapes of the metal foil along its length at each position in the width direction are different from each other, and each shape is a wave shape having repeating irregularities in the length direction of the metal foil. The length in the longitudinal direction on the surface of the metal foil is the surface distance. The minimum value among the surface distances at each position in the width direction of the metal foil is the minimum surface distance. The ratio of the difference between the surface distance at each position in the width direction of the metal foil and the minimum surface distance, relative to the minimum surface distance, is the elongation difference ratio in the length direction. The difference in elongation rate in the central region of the metal foil in the width direction is greater than the difference in elongation rate in the first end region and the second end region in the width direction. The elongation rate decreases from the central region toward the first end region, and decreases from the central region toward the second end region. The maximum value of the elongation difference in the central region is 30 × 10 －５ The following: The maximum value of the elongation difference in the first end region and the second end region is 10 × 10 －５ The following is Metal foil for spring components.

2. The central portion of the metal foil for the spring member in the width direction is the central portion in the width direction of the central region, and the length of the central region in the width direction is 30% of the length of the metal foil in the width direction. The first end region includes the first end in the width direction of the metal foil for the spring member, and the length of the first end region in the width direction is 20% of the length of the metal foil in the width direction. The second end region includes the second end in the width direction of the metal foil for the spring member, and the length of the second end region in the width direction is 20% of the length of the metal foil in the width direction. The metal foil for spring members according to claim 1.

3. The unit length in the width direction is 300 mm. The average value of the elongation rate at the aforementioned unit length is 10 × 10 －５ The following is Metal foil for spring member according to claim 1 or 2.

4. The metal foil includes any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium copper. Metal foil for spring member according to claim 1 or 2.

5. A method for manufacturing a metal foil for spring members, which is a strip-shaped metal foil used to manufacture spring members by wet etching, This includes rolling a base material to obtain the metal foil, The thickness of the metal foil is 100 μm or more and 200 μm or less. The shapes of the metal foil along its length at each position in the width direction are different from each other, and each shape is a wave shape having repeating irregularities in the length direction of the metal foil. The length in the longitudinal direction on the surface of the metal foil is the surface distance. The minimum value among the surface distances at each position in the width direction of the metal foil is the minimum surface distance. The ratio of the difference between the surface distance at each position in the width direction of the metal foil and the minimum surface distance, relative to the minimum surface distance, is the elongation difference ratio in the length direction. The difference in elongation rate in the central region of the metal foil in the width direction is greater than the difference in elongation rate in the first end region and the second end region in the width direction. The elongation rate decreases from the central region toward the first end region, and decreases from the central region toward the second end region. The maximum value of the elongation difference in the central region is 30 × 10 －５ The following: The maximum value of the elongation difference in the first end region and the second end region is 10 × 10 －５ The base material is rolled as follows: A method for manufacturing metal foil for spring components.

6. Forming a resist mask on a metal foil having a strip shape, A method for manufacturing a spring member, comprising patterning the metal foil by wet etching using the resist mask, The thickness of the metal foil is 100 μm or more and 200 μm or less. The shapes of the metal foil along its length at each position in the width direction are different from each other, and each shape is a wave shape having repeating irregularities in the length direction of the metal foil. The length in the longitudinal direction on the surface of the metal foil is the surface distance. The minimum value among the surface distances at each position in the width direction of the metal foil is the minimum surface distance. The ratio of the difference between the surface distance at each position in the width direction of the metal foil and the minimum surface distance, relative to the minimum surface distance, is the elongation difference ratio in the length direction. The difference in elongation rate in the central region of the metal foil in the width direction is greater than the difference in elongation rate in the first end region and the second end region in the width direction. The elongation rate decreases from the central region toward the first end region, and decreases from the central region toward the second end region. The maximum value of the elongation difference in the central region is 30 × 10 －５ The following: The maximum value of the elongation difference in the first end region and the second end region is 10 × 10 －５ The following is A method for manufacturing spring components.

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