Metal foil for spring member, method for producing metal foil for spring member, method for producing spring member, and spring member

Abstract

In the present invention, an elongation difference ratio between a first end region and a second end region in the width direction of a metal foil is greater than an elongation difference of a center region. The elongation difference ratio increases from the center region toward the first end region and increases from the center region toward the second end region. The maximum value of the elongation difference ratio in the center region is not more than 10×10-5. The maximum value of the elongation difference ratio for each of the first end region and the second end region is not more than 40×10-5.

Description

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

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

[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).

[0003] Japanese Patent Publication No. 2014-059345 Japanese Patent Publication No. 2020-170170

[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 of the metal foil is greater than the elongation rate at each end in the width direction. 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 of the metal foil is greater than the elongation rate at the center in the width direction. 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.

[0009] The metal foil for spring members used to solve the above problem is a strip-shaped metal foil used to manufacture spring members by wet etching. 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. 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 ratios in the first end region and the second end region in the width direction of the metal foil are greater than the elongation difference in the central region. The elongation difference ratio increases from the central region toward the first end region, and also increases from the central region toward the second end region. The maximum value of the elongation difference ratio in the central region is 10 × 10 －５ The following applies: The maximum value of the elongation difference in the first end region and the second end region is 40 × 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 includes rolling a base material to obtain the metal foil. 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. 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 difference in elongation between the first and second end regions in the width direction of the metal foil is greater than the difference in elongation in the central region, the difference in elongation increases from the central region toward the first end region, and increases from the central region toward the second end region, and the maximum value of the difference in elongation in the central region is 10 × 10－５ The following applies, where the maximum value of the elongation difference in the first end region and the second end region is 40 × 10 －５ The base material is rolled as follows:

[0011] A method for manufacturing metal foil for spring members to solve the above problems is a method for manufacturing metal foil for spring members, which is a strip-shaped metal foil used to manufacture spring members by wet etching. The method for manufacturing metal foil for spring members includes rolling a base material to obtain a plurality of rolled materials, calculating the elongation difference ratio for each rolled material, and selecting a metal foil from the plurality of rolled materials. 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. The sorting process is based on the following conditions for sorting the metal foil: the difference in elongation between the first and second end regions in the width direction of the metal foil is greater than the difference in elongation in the central region; the difference in elongation increases from the central region toward the first end region, and increases from the central region toward the second end region; and the maximum value of the difference in elongation in the central region is 10 × 10 －５ The following applies, where the maximum value of the elongation difference in the first end region and the second end region is 40 × 10 －５ This includes the following:

[0012] A method for manufacturing a spring member to solve 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 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. 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 ratios of the first end region and the second end region in the width direction of the metal foil are greater than the elongation difference ratio of the central region. The elongation difference ratio increases 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 ratio in the central region is 10 × 10 －５ The following applies: The maximum value of the elongation difference in the first end region and the second end region is 40 × 10 －５ The following applies:

[0013] According to the above configuration, even if the metal foil has a wave shape that results in a large difference in elongation at each end region in the width direction, the flow of the etching solution supplied to the metal foil will not become uneven. As a result, even when manufacturing spring members by wet etching of the metal foil, variations in the dimensions of the spring members within the plane of the metal foil will be suppressed.

[0014] In the above-mentioned metal foil for spring members, the thickness of the metal foil may be 100 μm or more and 200 μm or less.

[0015] According to the above-mentioned metal foil for spring members, even when manufacturing spring members by wet etching of a thick metal foil for spring members having a thickness of 100 μm to 200 μm, variations in the dimensions of the spring members within the plane of the metal foil can be suppressed.

[0016] In the metal foil for the spring member, in each of the first end region and the second end region, the minimum value of the elongation difference rate is 10.0×10 －５ or more, and in the central region, the minimum value of the elongation difference rate is 1.5×10 －５ or more, and at least one of the above may be satisfied.

[0017] According to the metal foil for the spring member, compared with the case where the minimum value in the elongation difference rate of the metal foil is a smaller value, it is possible to reduce the load in the manufacture of the metal foil.

[0018] 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.

[0019] According to the metal foil for the spring member, compared with the case where the central region is shorter and each end region is longer, it is possible to suppress an increase in the inclination of the elongation difference rate between the central region and each end region. Thereby, it is further possible to suppress the flow of the etching solution supplied to the metal foil from becoming non-uniform.

[0020] 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 may be 18×10 －５ or less. 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.

[0021] In the metal foil for the spring member, the metal foil may contain any one selected from the group consisting of a stainless alloy, beryllium copper, nickel tin copper, phosphor bronze, Kovar alloy, and titanium copper.

[0022] According to the metal foil for the spring member, since the metal foil for the spring member has high hardness and thus the degree of rolling is likely to vary within the metal foil, the effect of the upper limit value of the elongation difference rate in the central region and each end region is more remarkable.

[0023] The spring member for solving the above problems is a spring member for an electronic device. The spring member includes an inner frame portion, an outer frame portion, and a spring portion connecting the inner frame portion to the outer frame portion. The spring portion includes a leaf spring. The variation in the width of the leaf spring on the surface of the leaf spring is 10 μm or less.

[0024] According to the metal foil for the spring member, the manufacturing method of the metal foil for the spring member, the manufacturing method of the spring member, and the spring member of the present disclosure, dimensional variations can be suppressed in the spring member formed by wet etching of the metal foil.

[0025] FIG. 1 is a perspective view showing the structure of a metal foil for a spring member in one embodiment. FIG. 2 is a plan view showing a metal foil for measurement. FIG. 3 is a view showing a graph for explaining the elongation difference ratio together with the cross-sectional structure in the metal foil for measurement. FIG. 4 is a graph for explaining the elongation difference ratio. FIG. 5 is a plan view showing the structure of a spring member in one embodiment. FIG. 6 is a process diagram showing a step in one embodiment of a method for manufacturing a metal foil for a spring member. FIG. 7 is a process diagram showing a step in one embodiment of a method for manufacturing a metal foil for a spring member. FIG. 8 is a process diagram showing a step in one embodiment of a method for manufacturing a spring member. FIG. 9 is a process diagram showing a step in one embodiment of a method for manufacturing a spring member. FIG. 10 is a process diagram showing a step in one embodiment of a method for manufacturing a spring member. FIG. 11 is a process diagram showing a step in one embodiment of a method for manufacturing a spring member. FIG. 12 is a process diagram showing a step in one embodiment of a method for manufacturing a spring member. FIG. 13 is a plan view showing the structure in the metal foil for measurement in each example and each comparative example together with dimensions. FIG. 14 is a graph showing the distribution of the elongation difference ratio in the width direction of the metal foil of Example 1. FIG. 15 is a graph showing the distribution of the elongation difference ratio in the width direction of the metal foil of Example 2. FIG. 16 is a graph showing the distribution of the elongation difference ratio in the width direction of the metal foil of Example 3. FIG. 17 is a graph showing the distribution of the elongation difference ratio in the width direction of the metal foil of Example 4. FIG. 18 is a graph showing the distribution of the elongation difference ratio in the width direction of the metal foil of Comparative Example 1. FIG. 19 is a graph showing the distribution of the elongation difference ratio in the width direction of the metal foil of Comparative Example 2. FIG. 20 is a table showing the calculation results of the elongation difference ratio for each metal foil for each position in the width direction. FIG. 21 is a table showing the results of measuring the variation in width in the spring member manufactured using each metal foil.

[0026] Referring to FIGS. 1 to 21, one embodiment of a metal foil for a spring member, a method for manufacturing the metal foil for a spring member, and a method for manufacturing a spring member will be described. [Metal Foil for Spring Member] Referring to FIG. 1, the metal foil for a spring member will be described.

[0027] 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. 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.

[0028] 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.

[0029] The metal foil 10 includes a plurality of peaks 10A and valleys 10B located between the peaks 10A. The plurality of peaks 10A include a plurality of first peaks 10A aligned along a first side of a pair of sides extending along the length direction DL of the metal foil 10, and a plurality of second peaks 10A aligned along a second side. Viewed from a viewpoint opposite to the plane on which the metal foil 10 extends, each peak 10A has a shape that tapers from the side on which the peak 10A is located toward the center of the metal foil 10 in the width direction DW. The valleys 10B are sandwiched between the plurality of first peaks 10A and the plurality of second peaks 10A in the width direction DW. The valleys 10B are the portion that includes the center of the metal foil 10 in the width direction DW. 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.

[0030] 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 a spring member 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".

[0031] The metal foil 10 preferably contains 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.

[0032] The Vickers hardness of the metal foil 10 may be, for example, HV150 or higher, HV200 or higher, or HV250 or higher. The Vickers hardness is a value measured by a method conforming to JIS Z 2244:2009 "Vickers hardness test - Test method". The tensile strength of the metal foil 10 is, for example, 600 N / mm². ２ The above is sufficient, and 700 N / mm ２ The above is sufficient, and 800 N / mm ２ The above is acceptable. The tensile strength is the value measured according to the method conforming to JIS Z 2241:2011 "Tensile Test Method for Metallic Materials".

[0033] [Elongation Ratio] The elongation ratio will be explained with reference to Figures 2 to 4. When the metal foil 10 is placed on a horizontal surface, the position of the surface of the metal foil 10 relative to the horizontal plane, i.e., the height, is the surface position.

[0034] As shown in Figure 2, in surface position measurement, first, the rolled metal foil 10 is cut by a slitting process so that its width in the width direction DW becomes its width W, thereby obtaining a strip-shaped metal foil 10. The obtained metal foil 10 is wound into a roll. Next, a slitting process is performed in which the metal foil 10 is cut along its entire width in the width direction DW, i.e., its entire width, thereby cutting out a measuring foil 10M as a portion of the metal foil 10 in the length direction DL. The width W of the measuring foil 10M in the width direction DW is equal to the width of the metal foil 10 in the width direction DW. Next, the surface position of the surface 10MS of the measuring foil 10M is measured at predetermined intervals in the width direction DW, at each position in the length direction DL. The range in which the surface position is measured is the measurement range ZL.

[0035] The measurement range ZL excludes the non-measurement range ZE, which is the length DL of the measuring foil 10M, and both ends of that range. The measurement range ZL also excludes the non-measurement range (not shown), which is the width DW of the measuring foil 10M. The slitting process, which cuts the metal foil 10, can form a new wave shape on the measuring foil 10M that is different from the wave shape of the metal foil 10. The length of each non-measurement range ZE in the length 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 length DL is, for example, 100 mm. In the width 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 width DW is, for example, 10 mm from the end of the width DW.

[0036] 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.

[0037] 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 irregularities 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 ratio = (La - Lm) / Lm ... (Equation 1)

[0038] Figure 4 shows an example of the elongation difference 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 difference ratio of the metal foil 10 has its maximum value in the first end region RE1 or the second end region RE2 in the width direction DW. The elongation difference ratio of the metal foil 10 increases from the central region RC toward the first end region RE1 in the width direction DW, and also increases from the central region RC toward the second end region RE2 in the width direction DW.

[0039] 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.

[0040] 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 increases from the central region RC toward the first end region RE1. The elongation rate in the second intermediate region RI2 increases from the central region RC toward the second end region RE2.

[0041] The metal foil 10 of this embodiment satisfies the following six conditions: (Condition 1) The thickness T of the metal foil 10 is 100 μm or more and 200 μm or less. (Condition 2) The difference in elongation between the first end region RE1 and the second end region RE2 in the width direction DW of the metal foil 10 is greater than the difference in elongation between the central region RC. (Condition 3) The difference in elongation increases from the central region RC toward the first end region RE1. (Condition 4) The difference in elongation increases from the central region RC toward the second end region RE2. (Condition 5) The maximum value of the difference in elongation in the central region RC is 10 × 10 －５ The following applies: (Condition 6) The maximum value of the difference in elongation in the first end region RE1 and the second end region RE2 is 40 × 10 －５ The following applies:

[0042] In the metal foil 10 that satisfies conditions 2, 3, and 4, the difference in elongation due to rolling is greater in the first end region RE1 and the second end region RE2 than in the central region RC. Therefore, the central region RC is concave, or valley 10B, relative to the end regions RE1 and RE2 by the amount of the difference in elongation between the central region RC and each end region RE1 and RE2. As a result, when the metal foil 10 is wet-etched, the etching solution supplied to the metal foil 10 does not flow easily 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 tends to flow out of the metal foil 10 from only a portion of each end region RE1 and RE2. Also, when the etching solution is supplied to each end region RE1 and RE2 from a spray or the like, the etching solution tends to flow easily from the end regions RE1 and RE2 towards the central region RC, according to the difference in surface position between the central region RC and each end region RE1 and RE2. Therefore, the etching solution tends to remain in the central RC region.

[0043] As a result, the exchange of etching solution becomes less efficient in the central region RC, and fatigued etching solution, which is the etching solution whose etchant has been consumed by etching the metal foil 10, tends to remain in the central region RC.

[0044] Therefore, in the spring member 20 positioned on the central region RC of the metal foil 10, the etching rate per unit time is higher in the areas where etching with new etching solution is progressing compared to the areas where etching with fatigued etching solution continues. As a result, there is variation in the etching rate between the areas where etching with new etching solution is progressing and the areas where etching with fatigued etching solution continues. This variation in etching rate, i.e., the difference between the maximum and minimum etching rates, accumulates over time, and therefore increases as the time required to etch the metal foil 10 increases, i.e., as the thickness of the metal foil 10 increases.

[0045] In this respect, since the metal foil 10 of this embodiment satisfies condition 6, 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 toward each end region RE1, RE2, and from flowing toward the outside of the metal foil 10 from each end region RE1, RE2. 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, 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.

[0046] Furthermore, since the metal foil 10 of this embodiment satisfies condition 1, it is possible to suppress dimensional variations in the spring member 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 has a correspondingly longer etching time.

[0047] Thus, according to the metal foil 10 of this embodiment, even if the metal foil 10 has a wave shape such that the difference in elongation is large in each end region RE1, RE2 in the width direction DW, the non-uniformity of the etching solution flow supplied to the metal foil 10 can be suppressed. 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 can be suppressed.

[0048] 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. As a result, the uneven flow of the etching solution supplied to the metal foil 10 is further suppressed.

[0049] When a spring member 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 used to develop the resist layer located on the surface of the metal foil 10. The stripping solution is a liquid used to strip 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. According to the metal foil 10 of this embodiment, it is also possible to improve the uniformity of processing with these liquids, not just the etching solution.

[0050] Furthermore, the metal foil 10 of this embodiment 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 embodiment 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.

[0051] 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.

[0052] 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 18 × 10 －５ The following applies:

[0053] When the metal foil 10 satisfies condition 7, the elongation difference in the length direction DL is suppressed over the entire unit length, thus increasing 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 edge regions RE1 and RE2, is 18 × 10 －５ Therefore, the flatness of the metal foil 10 is improved.

[0054] 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.

[0055] (Condition 8) In each of the first end region RE1 and the second end region RE2, the minimum value of the elongation difference is 10.0 × 10 －５ That concludes the explanation. (Condition 9) In the central RC region, the minimum value of the elongation difference is 1.5 × 10 －５ That's all.

[0056] 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.

[0057] [Spring Member] 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 on which the spring member 20 extends.

[0058] 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 line 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 region defined by the outer frame portion 21. The spring portion 23 connects the inner frame portion 22 to the outer frame portion 21.

[0059] 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.

[0060] 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. The spring widths SWA and SWB are the widths of the leaf springs 23A1 and 23B1 on their surfaces. The variation in the spring widths SWA and SWB may be 10 μm or less. The variation in the spring width SWA is the value obtained by subtracting the minimum value from the maximum value among the spring widths SWA obtained for each of the multiple leaf springs 23A1 that are being measured.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] [Method for Manufacturing Metal Foil for Spring Components] The method for manufacturing 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 above-described conditions 1 to 6. The method for manufacturing the metal foil 10 will be described in more detail below with reference to the drawings.

[0065] Figures 6 and 7 schematically show the process of rolling a base material to form a metal foil 10. As shown in Figure 6, when a 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 transported along the transport 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 is parallel to the transport direction of the base material BM1.

[0066] 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.

[0067] 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 transport direction, metal foil 10 can be obtained with reduced residual stress compared to the rolled material BM2 before annealing.

[0068] 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.

[0069] 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 in 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.

[0070] 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.

[0071] 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 backup roll, an intermediate roll, and a pair of 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.

[0072] [Method for Manufacturing the Spring Member] The method for manufacturing the spring member 20 will be described with reference to Figures 8 to 12. The method for manufacturing 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 the above-described conditions 1 to 6. The method for manufacturing the spring member 20 will be described below with reference to the drawings.

[0073] 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 described 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] In this case, since the metal foil 10 satisfies conditions 1 to 6, dimensional variations are suppressed, especially in the spring member 20 that is positioned on the central region RC of the metal foil 10. 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 manufacture 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 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.

[0078] 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.

[0079] [Examples] Examples and comparative examples will be described with reference to Figures 13 to 21. [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, in which the length of the width direction DW was 300 mm and the thickness was 150 μm.

[0080] 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.

[0081] Measurement device: Nikon Corporation CNC image measurement system VMR-6555 Length of DL in the length direction of the measurement range ZL: 300 mm Length of DL in the length direction of the non-measurement range ZE: 100 mm Measurement interval in the length direction DL: 1 mm Measurement interval in the width direction DW: 15 mm

[0082] The calculation results for the elongation rate in Example 1 are shown in Figures 14 and 20. Furthermore, the average value of the elongation rate per unit length in the width direction DW was 17.8 × 10⁻⁶. －５ That was the case.

[0083] [Examples 2 to 4 and Comparative Examples 1 and 2] In Example 2, a metal foil 10 with a thickness of 150 μm was obtained by using a work roll with a larger crown amount than the work roll used in Example 1. In Example 3, a metal foil 10 with a thickness of 200 μm was obtained by lowering the reduction ratio compared to Example 1. In Example 4, a metal foil 10 with a thickness of 120 μm was obtained by changing the work roll shift amount and increasing the reduction ratio compared to Example 1. In Comparative Example 1, a metal foil 10 with a thickness of 150 μm was obtained by using a work roll with a smaller crown amount than the work roll used in Example 1. In Comparative Example 2, a metal foil 10 with a thickness of 150 μm was obtained by using a work roll with a smaller crown amount than the work roll used in Example 1 and by changing the work roll shift amount.

[0084] The calculation results for the elongation rate in Example 2 are shown in Figures 15 and 20. The average value of the elongation rate per unit length in the width direction DW is 10.2 × 10⁻⁶. －５ The calculation results for the elongation rate in Example 3 are shown in Figures 16 and 20, and the average value of the elongation rate per unit length in the width direction DW is 13.2 × 10 －５ The calculation results for the elongation rate in Example 4 are shown in Figures 17 and 20, and the average value of the elongation rate per unit length in the width direction DW is 16.0 × 10 －５ The calculation results for the elongation rate in Comparative Example 1 are shown in Figures 18 and 20, and the average value of the elongation rate per unit length in the width direction DW was 19.2 × 10⁻⁶. －５ The calculation results for the elongation rate in Comparative Example 2 are shown in Figures 19 and 20, and the average value of the elongation rate per unit length in the width direction DW is 24.7 × 10⁻⁶. －５ That was the case.

[0085] [Etching of Metal Foil] 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 of each measuring foil 10M. Then, the measuring foil 10M was wet-etched from both the front and back surfaces using the two resist masks RM1 and RM2. Unit regions, each corresponding to one spring member 20 and having a 20 mm square shape, were arranged in a grid pattern so that they were equally spaced 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 so that they were equally spaced in both the length direction DL and the width direction DW.

[0086] 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 adjacent.

[0087] Furthermore, each resist mask RM1 and RM2 has multiple unit patterns formed on them 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.

[0088] 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.

[0089] [Method for measuring spring width] The spring portion 23 of the spring member 20 contained in each etched measuring foil 10M was embedded with 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 in 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.

[0090] On the surface 10MS of the measuring foil 10M, the spring width SWA of the leaf spring 23A1 and the spring width SWB of the leaf spring 23B1 provided by each etching pattern were measured. 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 obtained by subtracting the spring width SWB from the spring width SWA for each unit pattern was calculated, and the directional difference of spring width, which is the average of the difference values ​​in each region RC, RE1, and RE2, was calculated.

[0091] 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.

[0092] [Evaluation Results] [Elongation Difference Ratio] As shown in Figures 14 and 20, in Example 1, the maximum elongation difference ratio in the central region RC was 7.9 × 10 －５ Therefore, the maximum value of the elongation difference in the first end region RE1 is 31.3 × 10⁻⁶. －５ Therefore, the maximum value of the elongation difference in the second end region RE2 is 38.1 × 10⁻⁶. －５ It was confirmed that... As shown in Figures 15 and 20, in Example 2, the maximum value of the elongation difference in the central region RC was 6.7 × 10 －５ Therefore, the maximum value of the elongation difference in the first end region RE1 is 24.8 × 10⁻⁶. －５ Therefore, the maximum value of the elongation difference in the second end region RE2 is 28.3 × 10⁻⁶. －５It was confirmed that... As shown in Figures 16 and 20, in Example 3, the maximum value of the elongation difference in the central region RC was 7.1 × 10 －５ Therefore, the maximum value of the elongation rate in the first end region RE1 is 29.3 × 10⁻⁶. －５ Therefore, the maximum value of the elongation difference in the second end region RE2 is 35.7 × 10⁻⁶. －５ It was confirmed that... As shown in Figures 17 and 20, in Example 4, the maximum value of the elongation difference in the central region RC was 6.5 × 10 －５ Therefore, the maximum value of the elongation difference in the first end region RE1 is 39.1 × 10⁻⁶. －５ Therefore, the maximum value of the elongation difference in the second end region RE2 is 34.2 × 10⁻⁶. －５ It was confirmed that this was the case.

[0093] As shown in Figures 18 and 20, in Comparative Example 1, the maximum value of the elongation difference in the central region RC was 6.9 × 10⁻⁶. －５ Therefore, the maximum value of the elongation difference in the first end region RE1 is 61.4 × 10⁻⁶. －５ Therefore, the maximum value of the elongation rate in the second end region RE2 is 56.2 × 10⁻⁶. －５ It was found that... As shown in Figures 19 and 20, in Comparative Example 2, the maximum value of the elongation rate in the central region RC was 10.6 × 10 －５ Therefore, the maximum value of the elongation difference in the first end region RE1 is 46.4 × 10⁻⁶. －５ Therefore, the maximum value of the elongation difference in the second end region RE2 is 71.2 × 10⁻⁶. －５ It was confirmed that this was the case.

[0094] [Spring Width] As shown in Figure 21, the variation in spring widths SWA and SWB was similar at all positions in the width direction DW in Examples 1 to 4, and was found to be suppressed to less than 9.5 μm. In contrast, the variation in spring widths SWA and SWB in Comparative Examples 1 and 2 was found to be large, exceeding 12.0 μm in the central region RC. Thus, it can be said that the metal foil 10 of Examples 1 to 4 suppresses the variation in spring widths SWA and SWB in the central region RC compared to Comparative Examples 1 and 2.

[0095] Furthermore, in the metal foils of Comparative Examples 1 and 2, the variation in spring widths SWA and SWB in each end region RE1 and RE2 was also found to be larger than that of the metal foils 10 of Examples 1 to 4. In the metal foils 10 of Comparative Examples 1 and 2, the difference between the elongation difference rate in each end region RE1 and RE2 and the elongation difference rate in the central region RC was found to be larger than that of the metal foils 10 of Examples 1 to 4. In other words, in the metal foils 10 of Comparative Examples 1 and 2, the slope of the elongation difference rate between the central region RC and each end region RE1 and RE1 was found to be larger than that of the metal foils 10 of Examples 1 to 4. Therefore, in Comparative Examples 1 and 2, in addition to the etching solution accumulating in the central region RC, variations in the length direction DL are likely to occur in the flow of the etching solution from the central region RC to each end region RE1 and RE2 in each end region RE1 and RE2. As a result, the flow of the etching solution becomes uneven in each end region RE1 and RE2, and consequently, the variation in the dimensions of the spring member 20 increases.

[0096] 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 each end region RE1, RE2 in the width direction DW, the non-uniformity of the flow of the etching solution supplied to the metal foil 10 can be suppressed. As a result, even if 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 20 within the plane of the metal foil 10 can be suppressed.

[0097] (2) Compared to the case where the central region RC is shorter and each end region RE1, RE2 is longer, the slope of the difference in elongation rate between the central region RC and each end region RE1, RE2 is suppressed to be larger. As a result, the non-uniformity of the flow of the etching solution supplied to the metal foil 10 is further suppressed.

[0098] (3) The average value of the elongation rate per unit length in the width direction DW is 18 × 10 －５ If the following conditions are met, the elongation difference in the length direction DL is suppressed over the entire unit length, thereby improving the flatness of the metal foil 10.

[0099] (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 10 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.

[0100] The above-described embodiment can be modified and implemented as follows: [Method for manufacturing metal foil] - In the rolling process, it is also possible to use a rolling apparatus 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.

[0101] - 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 curvature corresponding to the roll diameter. Therefore, depending on the material of the metal foil 10 and the size of the roll diameter when wound around the core C, it is preferable to anneal the rolled material BM2 while pulling it.

[0102] - It is also possible to manufacture the metal foil 10 by alternately repeating 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. [Metal foil] - The thickness of the metal foil 10 may be less than 100 μm or thicker than 200 μm. For example, the lower limit of the thickness of the metal foil 10 may be any of 100 μm, 90 μm, 80 μm, 70 μm, or 60 μm. The upper limit of the thickness of the metal foil 10 may be any of 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, or 250 μm. The combination of the lower limit and upper limit for the thickness of the metal foil 10 may be any lower limit selected from the lower limits described above and any upper limit selected from the upper limits described above.

[0103] 10...Metal foil for spring component 20...Spring component 21...Outer frame 22...Inner frame 23...Spring component E1...First end E2...Second end PC...Center RC...Center region RE1...First end region RE2...Second end region

Claims

1. A metal foil for a spring member, which is a strip-shaped metal foil used to manufacture a spring member by wet etching, wherein the shape of the metal foil along the length direction at each position in the width direction of the metal foil is 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, 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 of the first end region and the second end region in the width direction of the metal foil is greater than the elongation difference of the central region, the elongation difference ratio increases from the central region toward the first end region and from the central region toward the second end region, and the maximum value of the elongation difference ratio in the central region is 10 × 10 －５ The following applies, and the maximum value of the elongation difference in each of the first and second end regions is 40 × 10 －５ The following are metal foils for spring components.

2. The metal foil for a spring member according to claim 1, wherein the thickness of the metal foil is 100 μm or more and 200 μm or less.

3. The metal foil for the spring member has a minimum elongation ratio of 10.0 × 10 in each of the first and second end regions. －５ The above conditions must be met, and in the central region, the minimum value of the elongation rate must be 1.5 × 10 －５ A metal foil for a spring member according to claim 1 or 2, satisfying at least one of the above conditions.

4. The metal foil for a spring member according to claim 1 or 2, wherein the central portion of the metal foil for the spring member in the width direction is the central portion of the central region in the width direction, 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 portion of the metal foil for the spring member in the width direction, 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, and the second end region includes the second end portion of the metal foil for the spring member in the width direction, 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.

5. The unit length in the width direction is 300 mm, and the average value of the elongation difference in the unit length is 18 × 10 －５ The metal foil for a spring member according to claim 1 or 2, which is as follows:

6. The metal foil for a spring member according to claim 1 or 2, wherein the metal foil is selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium copper.

7. A method for manufacturing a metal foil for a spring member, which is a strip-shaped metal foil used to manufacture a spring member by wet etching, comprising: rolling a base material to obtain the metal foil, wherein the shapes of the metal foil along the length direction at each position in the width direction of the metal foil 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, 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 ratios of the first end region and the second end region in the width direction of the metal foil are greater than the elongation difference of the central region, the elongation difference ratio increases from the central region toward the first end region and from the central region toward the second end region, and the maximum value of the elongation difference ratio in the central region is 10 × 10 －５ The following applies, and the maximum value of the elongation difference in each of the first and second end regions is 40 × 10 －５ A method for manufacturing a metal foil for a spring member, comprising rolling the base material as follows:

8. A method for manufacturing a metal foil for a spring member, which is a strip-shaped metal foil used for manufacturing a spring member by wet etching, comprising: rolling a base material to obtain a plurality of rolled materials; calculating an elongation difference rate for each of the rolled materials; and selecting a metal foil from the plurality of rolled materials, wherein 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 irregularities 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; 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 selecting is based on the condition for selecting the metal foil that the elongation difference rates in the first end region and the second end region in the width direction of the metal foil are greater than the elongation difference in the central region; the elongation difference rate increases from the central region toward the first end region and also increases from the central region toward the second end region; the maximum value of the elongation difference rate in the central region is 10×10 －５ or less; and the maximum value of the elongation difference rate in each of the first end region and the second end region is 40×10 －５ or less. The method for manufacturing a metal foil for a spring member includes this.

9. A method for manufacturing a spring member, comprising: forming a resist mask on a strip-shaped metal foil; and patterning the metal foil by wet etching using the resist mask, wherein the shapes of the metal foil along the length direction at each position in the width direction of the metal foil 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; 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 rate in the length direction; the elongation difference rates of the first end region and the second end region in the width direction of the metal foil are greater than the elongation difference in the central region; the elongation difference rate increases from the central region toward the first end region, and increases from the central region toward the second end region; and the maximum value of the elongation difference rate in the central region is 10 × 10 －５ The following applies, and the maximum value of the elongation difference in each of the first and second end regions is 40 × 10 －５ The following is a method for manufacturing a spring member.

10. A spring member for electronic equipment, comprising an inner frame portion, an outer frame portion, and a spring portion connecting the inner frame portion to the outer frame portion, wherein the spring portion includes a leaf spring, and the variation in the width of the leaf spring on the surface of the leaf spring is 10 μm or less.

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