CN118679332A

CN118679332A - Metal foil for spring member, method for producing metal foil for spring member, and spring member for electronic device

Info

Publication number: CN118679332A
Application number: CN202380020722.0A
Authority: CN
Inventors: 岛村槙一; 小林昭彦; 相泽弘康
Original assignee: Takahashi Holdings Co ltd
Current assignee: Takahashi Holdings Co ltd
Priority date: 2022-02-10
Filing date: 2023-02-10
Publication date: 2024-09-20

Abstract

The metal foil for the spring member has a first region having a square shape with a side length of 300mm, and is used for forming the spring member. In the first region, the absolute value of the difference value obtained by subtracting the standard deviation of the thickness in the width direction orthogonal to the rolling direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less. In the first region, the absolute value of the difference value obtained by subtracting the second maximum value from the first maximum value is 0.8 μm or less.

Description

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

Technical Field

The present invention relates to a metal foil for a spring member, a method for manufacturing a metal foil for a spring member, and a spring member for an electronic device.

Background

A camera module provided in camera-equipped electronic devices such as a tablet terminal and a smart phone is provided with a driving mechanism for realizing automatic focusing and zooming. The form of the driving mechanism is known as a lens driving method and a sensor driving method. The drive mechanism of the lens drive system includes a leaf spring capable of changing the lens position in the optical axis direction of the lens. In contrast, the sensor driving type driving mechanism includes a leaf spring capable of changing the position of the image sensor in the optical axis direction of the lens (see, for example, patent documents 1 and 2).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2014-059345

Patent document 2: japanese patent laid-open No. 2020-170170

Disclosure of Invention

Problems to be solved by the invention

However, leaf springs are required to meet a specific spring load or deflection within a limited volume. In order to meet the requirements for spring load and deflection, the leaf springs need to be formed of a metal having a relatively high hardness.

The width and thickness of the leaf springs contribute significantly to the spring load and deflection. The metal foil as the raw material of the leaf spring is thinned to a predetermined thickness by rolling. Since the metal foil is formed of a metal having a relatively high hardness, it is difficult to uniformize the thickness of the metal foil by rolling, compared with the case of forming the metal foil of a relatively low hardness.

On the other hand, the plate spring is formed by wet etching of the metal foil. The thickness deviation of the metal foil causes deviation of etching amount, thereby causing deviation of width in the thickness direction of the plate spring. The variation in width in the thickness direction of the leaf spring causes variation in spring load and deflection of the leaf spring, and therefore it is required to suppress the variation in spring width in the thickness direction.

Means for solving the problems

One embodiment of the metal foil for the spring member includes a first region having a square shape with a side length of 300mm, and is used to form the spring member. In the first region, an absolute value of a differential value obtained by subtracting a standard deviation of a thickness in a width direction orthogonal to the rolling direction from a standard deviation of the thickness in the rolling direction is 0.15 μm or less, a maximum value of the thickness in the rolling direction is a first maximum value, a maximum value of the thickness in the width direction is a second maximum value, and an absolute value of a differential value obtained by subtracting the second maximum value from the first maximum value is 0.8 μm or less.

One embodiment of the method for producing a metal foil for a spring member includes: a step of rolling a base material; and a step of separating the metal foil for the spring member from the plurality of rolled materials after preparing the plurality of rolled materials obtained by rolling the base material. In the rolled material, a region having a square shape with a side length of 300mm and used for forming the spring member is a first region. In the first region, the maximum value of the thickness in the rolling direction is a first maximum value, and the maximum value of the thickness in the width direction orthogonal to the rolling direction is a second maximum value. In the step of sorting the metal foil for spring members, the rolled material having an absolute value of a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction in the first region of 0.15 μm or less and an absolute value of a difference value obtained by subtracting the second maximum value from the first maximum value of 0.8 μm or less is sorted from the plurality of rolled materials as the metal foil for spring members.

One embodiment of the spring member for electronic equipment is a spring member for electronic equipment using a metal foil for the spring member. The absolute value of the difference value obtained by subtracting the standard deviation of the thickness of the metal foil for the spring member in the width direction orthogonal to the rolling direction from the standard deviation of the thickness in the rolling direction is 0.15 [ mu ] m or less. In the metal foil for a spring member, the maximum value of the thickness in the rolling direction is a first maximum value, the maximum value of the thickness in the width direction is a second maximum value, and an absolute value of a difference value obtained by subtracting the second maximum value from the first maximum value is 0.8 μm or less.

Drawings

Fig. 1 is a perspective view showing a structure of a metal foil for a spring member according to an embodiment.

Fig. 2 is a plan view showing a structure of a spring member for an electronic device in this embodiment.

Fig. 3 is a process diagram for explaining a method of manufacturing a metal foil for a spring member in this embodiment.

Fig. 4 is a process diagram for explaining a method of manufacturing a metal foil for a spring member in this embodiment.

Fig. 5 is a process diagram for explaining a method of manufacturing a metal foil for a spring member in this embodiment.

Fig. 6 is a process diagram for explaining a method of manufacturing the spring member for the electronic device shown in fig. 2.

Fig. 7 is a process diagram for explaining a method of manufacturing the spring member for the electronic device shown in fig. 2.

Fig. 8 is a process diagram for explaining a method of manufacturing the spring member for the electronic device shown in fig. 2.

Fig. 9 is a process diagram for explaining a method of manufacturing the spring member for the electronic device shown in fig. 2.

Fig. 10 is a process diagram for explaining a method of manufacturing the spring member for the electronic device shown in fig. 2.

Fig. 11 is a plan view for explaining a measurement portion of the thickness of the metal foil for the spring member.

Fig. 12 is a table showing measurement results in the metal foils of examples and comparative examples.

Fig. 13 is a graph showing a relationship between the first absolute value and the differential value of the spring width.

Fig. 14 is a graph showing a relationship between the fourth absolute value and the differential value of the spring width.

Fig. 15 is a graph showing a relationship between the second absolute value and the differential value of the spring width.

Fig. 16 is a graph showing a relationship between the third absolute value and the differential value of the spring width.

Detailed Description

An embodiment of a metal foil for a spring member, a method for manufacturing a metal foil for a spring member, and a spring member for an electronic device will be described with reference to fig. 1 to 16.

[ Metal foil for spring Member ]

The metal foil for the spring member will be described with reference to fig. 1.

In the metal foil for spring member 10 (hereinafter, also referred to as metal foil) shown in fig. 1, a region for forming the spring member is a first region 10R1. The first region 10R1 has a square shape with a length of 300mm on one side. The metal foil 10 is a rolled material formed of a metal having a relatively high hardness capable of achieving the degree of spring load or deflection required for the spring member. The metal foil 10 has a strip shape extending in the rolling direction DR. The direction orthogonal to the rolling direction DR is the width direction DW. The thickness T of the metal foil 10 is, for example, 150 μm or less, preferably 50 μm or more and 120 μm or less. The thickness of the metal foil 10 has the following uniformity: the ratio of the difference between the maximum value and the minimum value of the thickness T of the metal foil 10 to the average value of the thicknesses of the base material is 3% or less.

The metal foil 10 satisfies the following condition 1.

(Condition 1) the absolute value of the differential value obtained by subtracting the standard deviation of the thickness in the width direction DW from the standard deviation of the thickness in the rolling direction DR is 0.15 μm or less, and the absolute value of the differential value obtained by subtracting the second maximum value from the first maximum value is 0.8 μm or less.

The standard deviation of the thickness in the rolling direction DR is a first standard deviation, and the standard deviation of the thickness in the width direction DW is a second standard deviation. The absolute value of the differential value obtained by subtracting the second standard deviation from the first standard deviation is the first absolute value. In addition, the first standard deviation is a standard deviation of the thickness at each point on a straight line extending along the rolling direction DR. In addition, the second standard deviation is a standard deviation of the thickness at each point on a straight line extending in the width direction DW.

The first maximum value is the maximum value of the thickness in the rolling direction DR. The second maximum value is the maximum value of the thickness in the width direction DW. The absolute value of the difference value obtained by subtracting the second maximum value from the first maximum value is a fourth absolute value.

Since the first absolute value is 0.15 μm or less and the fourth absolute value is 0.8 μm or less, thickness variation in the metal foil 10 can be suppressed. Therefore, in the spring member formed by wet etching of the metal foil 10, the variation in the spring width in the thickness direction is suppressed.

The metal foil 10 includes a front surface 10F and a rear surface 10B which is a surface opposite to the front surface 10F. The thickness T of the metal foil 10 is the distance between the front surface 10F and the back surface 10B. The maximum value and the minimum value of the thickness in the rolling direction DR are determined as follows. That is, the first measurement region R1R having a strip shape extending in the rolling direction DR is set for the first region 10R 1. The length of the first measurement region R1R in the width direction DW is, for example, 20mm. The maximum value and the minimum value of the thicknesses of the metal foil 10 measured at the points on the straight line included in the first measurement region R1R are the maximum value and the minimum value, respectively.

The maximum value and the minimum value of the thickness in the width direction DW are determined as follows. That is, the first region 10R1 is set with a band-shaped second measurement region R1W extending in the width direction DW. The length of the second measurement region R1W in the rolling direction DR is, for example, 20mm. The maximum value and the minimum value of the thicknesses of the metal foil 10 measured at the plurality of points on the straight line included in the second measurement region R1W are the maximum value and the minimum value, respectively.

In the metal foil 10, the more repeatedly the rolling is performed on the material used to manufacture the metal foil 10, the smaller the thickness deviation in the rolling direction DR becomes. Therefore, from the viewpoint of suppressing the deviation in the rolling direction DR, it is preferable to increase the number of times of rolling performed at the time of manufacturing the metal foil 10. However, from the viewpoint of achieving the spring load or deflection required for the spring member, the metal foil 10 for the spring member needs to have a thickness of a predetermined or more. Therefore, in the metal foil 10 for the spring member, it is difficult to perform rolling for the number of times that the thickness deviation in the rolling direction DR can be eliminated in the production of the metal foil 10. In contrast, in the metal foil 10, since the thickness variation in the width direction DW is governed by the surface state of the rolling rolls used for rolling, the variation tends to be suppressed regardless of the number of times of rolling. Therefore, the metal foil 10 tends to have the second standard deviation easily equal to or smaller than the first standard deviation. Further, the metal foil 10 tends to have the second maximum value easily equal to or less than the first maximum value.

On the other hand, when the metal foil 10 is subjected to wet etching for forming a through hole penetrating the metal foil 10 in the thickness direction of the metal foil 10, the time required for forming the through hole is shorter as the thickness of the metal foil 10 becomes thinner. Then, the through-holes formed in the metal foil 10 form a flow of the etching liquid between the front surface 10F and the rear surface 10B of the metal foil 10, on the one hand, and hardly contribute to progress of isotropic etching of the metal foil 10 in a direction perpendicular to the through-hole direction, on the other hand. In contrast, the thicker the thickness of the metal foil 10, the longer the time required to form the through-hole. Thus, the thicker portions of the metal foil 10 have a greater contribution to the progress of the isotropic etching of the metal foil 10.

Therefore, the first standard deviation and the first maximum value can be used as an indicator of the easiness of etching isotropically in the rolling direction DR in the thickness of the metal foil 10. In addition, the second standard deviation and the second maximum value can be used as indicators of the ease of occurrence of isotropic etching in the width direction DW in the thickness of the metal foil 10. The first absolute value and the fourth absolute value can be used as an index of the easiness of isotropic etching in the rolling direction DR with respect to the width direction DW in which isotropic etching is difficult to occur.

In this regard, when the metal foil 10 satisfies the condition 1, the occurrence easiness of isotropic etching in the rolling direction DR can be suppressed from becoming excessively high, based on the occurrence easiness of isotropic etching in the width direction DW. Therefore, a desired shape is easily obtained in the spring member formed by etching the metal foil 10.

In the first region 10R1, the variance of the thickness T in the rolling direction DR is a first variance. That is, the first variance is a variance of the thickness T at each point on a straight line along the rolling direction DR. In the first region 10R1, the variance of the thickness T in the width direction DW is the second variance. That is, the second variance is a variance of the thickness T at each point on a straight line along the width direction DW.

In the first region 10R1, a difference value between a maximum value and a minimum value of the thickness T in the rolling direction DR is a first difference value. That is, the thickness T at each point on a straight line along the rolling direction DR is a first thickness, and the difference value between the maximum value and the minimum value of the first thickness is a first difference value. In the first region 10R1, a difference value between a maximum value and a minimum value of the thickness T in the width direction DW is a second difference value. That is, the thickness at each point on a straight line along the width direction DW is the second thickness, and the difference value between the maximum value and the minimum value of the second thickness is the second difference value.

The metal foil 10 preferably satisfies at least one of the following conditions 2 to 5. That is, the metal foil 10 may satisfy only one of the conditions 2 to 5, or may satisfy two or more selected from the conditions 2 to 5.

(Condition 2) the absolute value of the difference value obtained by subtracting the second variance from the first variance is 0.15 μm ² or less.

The absolute value of the difference value obtained by subtracting the second variance from the first variance is the second absolute value.

(Condition 3) the difference value obtained by subtracting the second standard deviation from the first standard deviation is 0.15 μm or less.

The difference value obtained by subtracting the second standard deviation from the first standard deviation is a third difference value.

(Condition 4) the difference value obtained by subtracting the second variance from the first variance is 0.15 μm ² or less.

The difference value obtained by subtracting the second variance from the first variance is a fourth difference value.

(Condition 5) the absolute value of the difference value obtained by subtracting the second difference value from the first difference value is 0.8 μm or less.

The absolute value of the difference value obtained by subtracting the second difference value from the first difference value is a third absolute value.

In the case where the metal foil 10 satisfies the conditions 2 to 5, too, the occurrence easiness of isotropic etching in the rolling direction DR can be suppressed from becoming excessively high, based on the occurrence easiness of isotropic etching in the width direction DW, as in the case where the condition 1 is satisfied. Therefore, a desired shape is easily obtained in the spring member formed by etching of the metal foil 10.

As described above, the metal foil 10 is formed of a metal having a high hardness capable of achieving the degree of spring load or deflection required for the spring member manufactured using the metal foil 10. The metal foil 10 may be formed of, for example, a stainless steel alloy or a copper alloy. The stainless steel alloy may be, for example, JIS G4313: 2011 stainless steel alloy specified by "stainless steel strip for spring". The copper alloy may be, for example, JIS H3130: 2018 "beryllium copper, titanium copper, phosphor bronze, nickel tin copper, nickel white plate, and nickel white bar for spring".

The metal foil 10 preferably includes any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel tin copper, phosphor bronze, colsen alloy, titanium copper. Accordingly, the metal foil 10 can have a high hardness, and thus the durability of the spring member formed of the metal foil 10 can be improved.

[ Spring Member ]

The spring member will be described with reference to fig. 2. Fig. 2 schematically shows the planar configuration of the spring element from a point of view opposite the plane in which the spring element expands.

As shown in fig. 2, the spring member 20 includes an outer frame 21, an inner frame 22, and a spring 23. The spring member 20 is a leaf spring. In the example shown in fig. 2, 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 shape of the outer frame 21 and the outer shape of the inner frame 22 may be changed according to the shape of other members of the driving mechanism of the camera module in which the spring member 20 is mounted, that is, members other than the spring member 20. The inner frame portion 22 is located in the region divided by the outer frame portion 21. The spring portion 23 connects the inner frame portion 22 and the outer frame portion 21.

In the lens driving type driving mechanism, a pair of spring members 20 are arranged so as to sandwich the lens in the optical axis direction of the lens. The position of the inner frame portion 22 connected to each outer frame portion 21 with respect to the outer frame portion 21 changes in the optical axis direction, whereby the position of the lens changes in the optical axis direction. Thus, the lens driving system driving mechanism can correct the shake.

In contrast, in the sensor-driven driving mechanism, the pair of spring members 20 are disposed so as to sandwich the imaging sensor in the optical axis direction of the lens. The position of the inner frame portion 22 connected to each outer frame portion 21 with respect to the outer frame portion 21 changes in the optical axis direction, whereby the position of the image pickup sensor in the optical axis direction of the lens changes. Thus, the shake can be corrected by the sensor-driven driving mechanism.

In the spring member 20, the length in the direction orthogonal to the direction in which each side of the outer frame 21 extends in a plan view facing the plane in which the spring member 20 extends is the width of the spring member 20 in the outer frame 21. In a plan view facing the plane in which the spring members 20 extend, the length of the inner frame 22 along the radial direction of the inner frame 22 is the width of the spring members 20 in the inner frame 22. In a plan view facing the plane in which the spring member 20 extends, the line width of the fold line in the plan view of the spring portion 23 is the width of the spring portion 23, that is, the spring width SW.

The electronic device on which the camera module including the spring member 20 is mounted may be, for example, a mobile phone terminal, a smart phone, a tablet terminal, a notebook computer, or the like.

[ Method for producing Metal foil for spring Member ]

A method of manufacturing the metal foil 10 will be described with reference to fig. 3 to 5.

The method for manufacturing the metal foil 10 includes: a step of rolling a base material; and a step of, after preparing a plurality of rolled materials obtained by rolling the base material, separating the metal foil 10 from the plurality of rolled materials. In the step of sorting the metal foil 10, a rolled material satisfying the above condition 1 is sorted out of a plurality of rolled materials as the metal foil 10. The method for producing the metal foil 10 may further include at least one of the above conditions 2 to 5 in the condition for separating the metal foil 10 from the plurality of rolled materials. That is, the conditions for sorting the metal foil 10 may include only one of the conditions 2 to 5, or may include two or more selected from the conditions 2 to 5.

Hereinafter, a method for manufacturing the metal foil 10 will be described in more detail with reference to the drawings.

Fig. 3 schematically shows a process of rolling a base material for forming the metal foil 10. Fig. 4 schematically illustrates a process of annealing a rolled material.

As shown in fig. 3, when the metal foil 10 is manufactured, a base material BM1 having a band shape extending in the rolling direction DR is first prepared. Next, the base material BM1 is transported in the transport direction toward the rolling device RE provided with the pair of rolling rolls RL1, RL2 so that the rolling direction DR of the base material BM1 is parallel to the transport direction in which the base material BM1 is transported.

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 RL 2. Thereby, the thickness of the base material BM1 is reduced, and the base material BM1 is stretched in the conveying direction, whereby the rolled material BM2 can be obtained. The rolled material BM2 is wound into a coil C. The rolled material BM2 may be processed in a state stretched into a belt shape, instead of being wound into the coil C. The thickness of the rolled material BM2 is, for example, 150 μm or less, preferably 50 μm or more and 120 μm or less.

As shown in fig. 4, the rolled material BM2 is annealed by an annealing device AE in order to remove residual stress accumulated in the rolled material BM2 formed by rolling the base material BM 1. Thereby, the annealed rolled material BM3 can be obtained. Since annealing of the rolled material BM2 is performed while pulling the rolled material BM2 in the conveying direction, the rolled material BM3 having reduced residual stress compared with the rolled material BM2 before annealing can be obtained.

As described above, the material forming the base material BM1 may be any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel tin copper, phosphor bronze, colsen alloy, and titanium copper. These metals have a higher hardness, in other words, are less likely to be elongated than the softer metal, which is the lower hardness metal, and therefore, the base material BM1 is likely to have a variation in the degree of rolling. In addition, the rolling degree is also liable to vary among the plurality of base materials BM 1. Therefore, the effectiveness is high in the case where the sorting condition of the metal foil 10 formed by rolling of the base material BM1 includes the above condition 1.

Fig. 5 schematically shows a process of measuring the thickness of the metal foil 10 formed through the rolling process.

As shown in fig. 5, after a plurality of rolled materials BM3 obtained by rolling are prepared, the thickness of the first region for forming the spring member 20 in each rolled material BM3 is measured by the measuring device ME. Thus, at least the first absolute value is calculated for the first region of each rolled material BM 3. Then, the rolled material BM3 satisfying the above condition 1 among the plurality of rolled materials BM3 is sorted into the metal foils 10, and the sorted metal foils 10 are used for manufacturing the spring member 20.

The first variance, the second absolute value, and the third absolute value may be calculated for the first region of each rolled material BM 3. Further, at least one of the conditions 2 to 5 may be increased for the conditions for sorting the metal foil 10 from the rolled material BM 3. That is, the conditions for sorting the metal foil 10 from the rolled material BM3 may be increased by only one of the conditions 2 to 5, or may be increased by two or more selected from the conditions 2 to 5. The measurement device ME may be a contact type measurement device or a non-contact type measurement device.

For example, a length meter can be used as the contact type measuring device. For example, a noncontact measuring device is used which includes an irradiation unit for irradiating X-rays and a detection unit for detecting fluorescent X-rays. In the case of using this measuring device, first, the metal foil 10 is irradiated with X-rays by the irradiation unit, and fluorescent X-rays emitted from the metal foil 10 are detected by the detection unit. Since the intensity of the fluorescent X-rays detected by the detection unit depends on the thickness of the metal foil 10, the thickness of the metal foil 10 can be grasped from the intensity of the fluorescent X-rays.

The first standard deviation, the second standard deviation, the first variance, the second variance, the first differential value, and the second differential value can be changed by changing at least one of the following. The above values can be changed by changing at least one of the rotational speeds of the rolling rolls RL1, RL2, the pressing force between the rolling rolls RL1, RL2, the temperatures of the rolling rolls RL1, RL2, and the number of the rolling rolls RL1, RL 2. That is, only one of the rotational speeds of the rolling rolls RL1, RL2, the pressing force between the rolling rolls RL1, RL2, the temperatures of the rolling rolls RL1, RL2, and the number of the rolling rolls RL1, RL2 may be changed. Alternatively, any two or more of the rotational speeds of the rolling rolls RL1, RL2, the pressing force between the rolling rolls RL1, RL2, the temperatures of the rolling rolls RL1, RL2, and the number of the rolling rolls RL1, RL2 may be changed.

[ Method of producing spring Member ]

A method of manufacturing the spring member 20 will be described with reference to fig. 6 to 10.

As shown in fig. 6, in manufacturing the spring member 20, first, a first resist layer PR1 is formed on the front surface 10F of the metal foil 10, and a second resist layer PR2 is formed on the rear surface 10B. In the example described with reference to fig. 6 to 10, each of the resist layers PR1 and PR2 is formed of positive photoresist, but each of the resist layers PR1 and PR2 may be formed of negative photoresist.

Next, as shown in fig. 7, a first photomask PM1 is disposed on the first resist layer PR1, and a second photomask PM2 is disposed on the second resist layer PR 2. 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.

As shown in fig. 8, the exposed resist layers PR1, PR2 are developed, whereby a first resist mask RM1 is formed from the first resist layer PR1 and a second resist mask RM2 is formed from the second resist layer PR 2.

As shown in fig. 9, the metal foil 10 is wet etched using the resist masks RM1, RM 2. At this time, the metal foil 10 is etched from both the front surface 10F and the back surface 10B. Thus, through holes penetrating in the thickness direction of the metal foil 10 are formed in the metal foil 10, and as a result, the outer frame 21, the inner frame 22 separated from the outer frame 21, and the spring 23 connecting the inner frame 22 and the outer frame 21 are formed.

At this time, since the metal foil 10 satisfies the condition 1, the spring member 20 having a desired shape in the thickness direction of the metal foil 10 is easily obtained. Further, since the metal foil 10 satisfies the condition 1, even if the wet etching condition is not changed according to the variation in the thickness of the metal foil 10, the spring member 20 in which the variation in the spring width in the thickness direction of the spring member 20 is suppressed within the predetermined range can be obtained. Therefore, in the production of the spring member 20, it is not necessary to change the wet etching conditions according to the thickness variation, and therefore, it is possible to eliminate errors in the combination of the thickness variation and the wet etching conditions.

As shown in fig. 10, after the resist masks RM1, RM2 are removed from the etched metal foil 10, the spring member 20 is cut out from the etched metal foil 10, whereby the spring member 20 can be obtained.

Examples (example)

The embodiment and the comparative example will be described with reference to fig. 11 to 16.

Example 1

First, a rolled material is formed by performing a rolling process on a base material made of titanium copper. Subsequently, an annealing step is performed on the rolled material. Thus, the metal foil of example 1 having a design value of 120 μm in thickness was obtained.

Examples 2 to 8 and comparative examples 1 to 3

In example 1, the metal foils of examples 2 to 8 and comparative examples 1 to 3 were obtained by changing at least one of the rotation speed of the rolling rolls, the pressing force between the rolling rolls, the temperature of the rolling rolls, and the number of the rolling rolls when rolling the base material, and otherwise, the same as example 1.

[ Evaluation method ]

[ Measurement of thickness ]

A method for measuring the thickness of the metal foil 10 will be described with reference to fig. 11.

As shown in fig. 11, a square measuring metal foil 30 having a length of 300mm on one side was cut out from the metal foils of each example and each comparative example. The measuring metal foils 30 are cut out from the respective metal foils in such a manner that the direction in which the first side of the measuring metal foil 30 extends is parallel to the rolling direction DR of the metal foil and the direction in which the second side of the measuring metal foil 30 extends is perpendicular to the width direction DW of the metal foil. Each measuring metal foil 30 includes a measuring region 30A having a square shape including the center of the measuring metal foil 30, and a peripheral region 30B having a rectangular frame shape surrounding the measuring region 30A. At this time, the width W3 of the peripheral region 30B was set to 10mm.

In addition, a first measurement region R1R having a belt shape extending in the rolling direction DR and a second measurement region R1W having a belt shape extending in the width direction DW are set in the measurement region 30A. At this time, the width W1, which is the length in the width direction DW of the first measurement region R1R, is set to 20mm, and the width W2, which is the length in the rolling direction DR of the second measurement region R1W, is set to 20mm.

Then, the thickness of the metal foil was measured in the entire region obtained by subjecting the first measurement region R1R to 14 equal parts in the rolling direction DR. The thickness of the metal foil 30 was measured in the entire region obtained by dividing the second measurement region R1W by 14 in the width direction DW.

The thickness was measured at the point in each region where the diagonal lines joining the two opposite corners intersect with each other. That is, the thickness was measured at each point located on the same straight line. For each measuring metal foil, the thickness was measured at 14 points in the rolling direction DR and 14 points in the width direction DW. However, in the area where the first measurement area R1R and the second measurement area R1W intersect, the measurement point in the rolling direction DR and the measurement point in the width direction DW are the same, and thus the thickness of each measurement metal foil is measured at 27 points in total. Then, the measured value was rounded to a decimal point and then the second place, thereby being a measured value of the thickness in each region.

From these measured values, a first standard deviation, a second standard deviation, a first variance, and a second variance are calculated. Further, a third difference value, which is a difference value obtained by subtracting the second standard deviation from the first standard deviation, and a first absolute value, which is an absolute value of the third difference value, are calculated. Further, a fourth difference value, which is a difference value obtained by subtracting the second variance from the first variance, and a second absolute value, which is an absolute value of the fourth difference value, are calculated. Further, a third absolute value, which is an absolute value of the difference value obtained by subtracting the second difference value from the first difference value, and a fourth absolute value, which is an absolute value of the difference value obtained by subtracting the maximum value of the thickness in the width direction DW from the maximum value of the thickness in the rolling direction DR, are calculated.

For the measurement of the thickness of the metal foil 30 for measurement, a contact thickness measuring instrument (manufactured by Nikon, inc., MH-15M) was used. When measuring the thickness, first, the power supply of the counter of the plate thickness measuring machine attached to the measuring instrument is turned on in a state where the measuring contact is brought into contact with the chassis, thereby performing zero point alignment. Then, a measuring metal foil is placed between the measuring contact and the chassis, and then the thickness of each part of the measuring metal foil is measured by lowering the measuring contact.

[ Evaluation of etched Pattern ]

A resist mask having a plurality of openings corresponding to the shape of the spring member 20 is formed on the front and rear surfaces of each measuring metal foil 30, and the measuring metal foil 30 is wet etched from both the front and rear surfaces using the two resist masks. In the measurement region 30A, a square unit region corresponding to one spring member 20 and having a square shape of 20mm square is arranged in a lattice shape so as to be full in both the rolling direction DR and the width direction DW. Therefore, the unit patterns corresponding to the shape of one spring member 20 are also arranged in a lattice shape on each resist mask so as to be full in both the rolling direction DR and the width direction DW.

In the unit pattern, at a portion where the spring part 20 having the folded-line-shaped spring part 23 is formed, the opening width of the resist pattern corresponding to the gap between the mutually parallel and adjacent line segments in the spring part 23 is set to 100 μm, and the pitch between the adjacent line segments is set to 200 μm. Here, the pitch of the adjacent line segments refers to the distance between center lines set for each line segment among the line segments that are parallel to each other and adjacent to each other in the design of the etching pattern.

In addition, in each of the resist masks, a plurality of unit patterns are formed on each of the resist masks so that the whole of one unit pattern of the resist mask located on the surface of the metal foil for measurement 30 overlaps the whole of one unit pattern of the resist mask located on the rear surface of the metal foil for measurement 30 in a plan view facing the surface of the metal foil for measurement 30.

Using such a resist mask, a plurality of etching patterns corresponding to the shape of the spring member 20 are formed in the metal foil for measurement 30. In the etching pattern, the design value of the spring width of the spring portion 23 in a plan view was set to 30 μm.

The spring portions 23 of the spring members 20 present on each of the metal foils 30 for measurement after etching are covered with synthetic resin. Then, the coated spring portion 23 is cut using a microtome, whereby the cross section of the spring portion 23 in a plane orthogonal to the direction in which the line segment included in the spring portion extends is exposed.

In the cross section of the spring portion 23, the spring width at the following positions was measured. That is, in the spring portion 23, the spring width on the front surface of the metal foil for measurement 30, the spring width on the back surface of the metal foil for measurement 30, and the spring widths in 3 planes sandwiched between the front surface and the back surface of the metal foil for measurement 30 in a plane obtained by dividing the spring portion 23 by 4 in the thickness direction were measured. That is, in the case where the depth on the surface of the metal foil 30 for measurement is set to 0 μm, in the etched pattern, the spring width at the depth of 0 μm, the spring width at the depth of about 30 μm, the spring width at the depth of about 60 μm, the spring width at the depth of about 90 μm, and the spring width at the depth of about 120 μm are measured. For measuring the spring width of the spring portion 23, a digital microscope (VHX-7000, manufactured by kean corporation) was used, and the magnification of the objective lens was set to 200 times in the digital microscope.

Further, the etching patterns obtained from the metal foil for measurement 30 of each example and each comparative example were calculated as the first standard value, the standard deviation of the spring width, the percentage of the second standard value, 3σ with respect to the average value of the spring width, and the variance of the spring width.

The spring widths at the above 5 positions in the thickness direction were measured for each unit pattern included in the metal foil for measurement 30, among all the springs included in the spring portion 23. Then, a maximum value and a minimum value are determined for each spring, a differential value obtained by subtracting the minimum value from the maximum value is calculated, and an average value of the spring widths is calculated. Then, an average value of the maximum values is calculated from the maximum values determined for all the springs, and the average value is set as the maximum value of the spring width in the measuring metal foil 30. The average value of the minimum values is calculated from the minimum values determined for all the springs, and the minimum value is set as the minimum value of the spring width in the measuring metal foil 30. Further, an average value of the differential values is calculated from the differential values calculated for all the springs, and the average value is set as the differential value of the measuring metal foil 30. The average value calculated for all springs was calculated, and the average value was set as the average value of the metal foil for measurement 30.

Further, for the etching patterns obtained from the measuring metal foil 30 of each example and each comparative example, the first standard value, the standard deviation of the spring width, the second standard value, and the percentage of 3σ to the average value of the spring width were calculated. When calculating the percentage of 3σ relative to the average value of the spring width, the average value set for each measuring metal foil 30 is used. The first standard value is a percentage of a difference value between the spring width and a design value of the spring width. The differential value set for each measuring metal foil 30 is used for the calculation of the first standard value. In addition, the second standard value is a percentage of the standard deviation of the spring width with respect to the design value of the spring width.

In calculating the standard deviation of the spring width, first, the standard deviation of the spring width is calculated from the thicknesses of 5 portions measured for each spring. Next, an average value of the standard deviations is calculated from the standard deviations calculated for all the springs, and the average value is set as the standard deviation of the spring width of the metal foil for measurement 30. The standard deviation set for each measuring metal foil 30 is used for the calculation of the second standard value.

In calculating the variance of the spring width, the variance of the spring width is first calculated from the thicknesses of 5 parts measured for each spring. Then, the average value of the variances is calculated from the variances calculated for all the springs, and the variance of the spring width in the metal foil for measurement 30 on the average value is calculated.

[ Evaluation results ]

The evaluation results of the thickness of the metal foil for measurement 30 and the spring width of the etched pattern will be described with reference to fig. 12 to 14.

Fig. 12 shows the measurement results of the thickness of each measuring metal foil 30 and the measurement results of the spring width of the etching pattern formed by wet etching each measuring metal foil 30. In fig. 12, the fourth absolute value is an absolute value of a difference value obtained by subtracting the maximum value of the thickness in the width direction DW from the maximum value of the thickness in the rolling direction DR.

As shown in fig. 12, it can be confirmed that the first standard deviation is 0.313 μm in example 1, 0.291 μm in example 2, 0.389 μm in example 3, and 0.261 μm in example 4. It was confirmed that the first standard deviation was 0.516 μm in example 5, 0.421 μm in example 6, 0.532 μm in example 7, and 0.524 μm in example 8. It was confirmed that the first standard deviation was 0.766 μm in comparative example 1, 0.571 μm in comparative example 2, and 0.498 μm in comparative example 3.

It was confirmed that the second standard deviation was 0.243 μm in example 1, 0.303 μm in example 2, 0.332 μm in example 3, and 0.184 μm in example 4. It was confirmed that the second standard deviation was 0.447 μm in example 5, 0.311 μm in example 6, 0.420 μm in example 7, and 0.412 μm in example 8. It was confirmed that the second standard deviation was 0.260 μm in comparative example 1, 0.218 μm in comparative example 2, and 0.307 μm in comparative example 3.

From this, it was confirmed that the third differential value was 0.069 μm in example 1, -0.012 μm in example 2, 0.057 μm in example 3, and 0.077 μm in example 4. It was confirmed that the third differential value was 0.068 μm in example 5, 0.110 μm in example 6, 0.112 μm in example 7, and 0.111 μm in example 8. It was confirmed that the third differential value was 0.507 μm in comparative example 1, 0.353 μm in comparative example 2, and 0.191 μm in comparative example 3.

It was confirmed that the first absolute value was 0.069 μm in example 1, 0.012 μm in example 2, 0.057 μm in example 3, and 0.077 μm in example 4. It was confirmed that the first absolute value was 0.068 μm in example 5, 0.110 μm in example 6, 0.112 μm in example 7, and 0.111 μm in example 8. It was confirmed that the first absolute value was 0.507 μm in comparative example 1, 0.353 μm in comparative example 2, and 0.191 μm in comparative example 3.

As described above, it was confirmed that the first absolute value was 0.15 μm or less in the metal foil for measurement 30 of examples 1 to 8, and that the first absolute value was more than 0.15 μm in the metal foil for measurement 30 of comparative examples 1 to 3. Specifically, it was confirmed that the first absolute value of the metal foil for measurement 30 in examples 1 to 8 was 0.012 μm or more and 0.112 μm or less, and that the first absolute value of the metal foil for measurement 30 in comparative examples 1 to 3 was 0.191 μm or more and 0.507 μm or less. It was confirmed that the first standard deviation was larger than the second standard deviation in the metal foils 30 for measurement of examples 1, 3 to 8 and the metal foils 30 for measurement of comparative examples 1 to 3, and that the first standard deviation was smaller than the second standard deviation in example 2.

It was confirmed that the first variance was 0.098 μm ² in example 1, 0.085 μm ² in example 2, 0.151 μm ² in example 3, and 0.068 μm ² in example 4. It was confirmed that the first variance was 0.266 μm ² in example 5, 0.177 μm ² in example 6, 0.283 μm ² in example 7, and 0.274 μm ² in example 8. It was confirmed that the first variance was 0.587 μm ² in comparative example 1, 0.326 μm ² in comparative example 2, and 0.248 μm ² in comparative example 3.

It was confirmed that the second variance was 0.059 μm ² in example 1, 0.092 μm ² in example 2, 0.110 μm ² in example 3, and 0.034 μm ² in example 4. It was confirmed that the second variance was 0.200 μm ² in example 5, 0.096 μm ² in example 6, 0.176 μm ² in example 7, and 0.170 μm ² in example 8. It was confirmed that the second variance was 0.067 μm ² in comparative example 1, 0.048 μm ² in comparative example 2, and 0.095 μm ² in comparative example 3.

From this, it was confirmed that the fourth differential value was 0.039 μm ² in example 1, -0.007 μm ² in example 2, 0.041 μm ² in example 3, and 0.034 μm ² in example 4. It was confirmed that the fourth differential value was 0.066 μm ² in example 5, 0.081 μm ² in example 6, 0.107 μm ² in example 7, and 0.104 μm ² in example 8. It was confirmed that the fourth differential value was 0.520 μm ² in comparative example 1, 0.278 μm ² in comparative example 2, and 0.154 μm ² in comparative example 3.

It was confirmed that the second absolute value was 0.039 μm ² in example 1, 0.007 μm ² in example 2, 0.041 μm ² in example 3, and 0.034 μm ² in example 4. It was confirmed that the second absolute value was 0.066 μm ² in example 5, 0.081 μm ² in example 6, 0.107 μm ² in example 7, and 0.104 μm ² in example 8. It was confirmed that the second absolute value was 0.520 μm ² in comparative example 1, 0.278 μm ² in comparative example 2, and 0.154 μm ² in comparative example 3. As described above, it was confirmed that the second absolute value of the metal foil for measurement 30 in examples 1 to 8 was 0.15 μm ² or less, while the second absolute value of the metal foil for measurement 30 in comparative examples 1 to 3 was more than 0.15 μm ². Specifically, it was confirmed that the second absolute value was 0.007 μm ² to 0.107 μm ² in the metal foil for measurement 30 of examples 1 to 8, and 0.154 μm ² to 0.520 μm ² in the metal foil for measurement 30 of comparative examples 1 to 3.

It was confirmed that the third absolute value was 0.2 μm in example 1,0 μm in example 2, 0.3 μm in example 3, and 0.3 μm in example 4. It was confirmed that the third absolute value was 0.5 μm in example 5, 0.4 μm in example 6, 0.2 μm in example 7, and 0.4 μm in example 8. It was confirmed that the third absolute value was 1.6 μm in comparative example 1, 1.2 μm in comparative example 2, and 0.9 μm in comparative example 3.

It was confirmed that the fourth absolute value was 0 μm in example 1, 0 μm in example 2, 0.4 μm in example 3, and 0 μm in example 4. It was confirmed that the fourth absolute value was 0.8 μm in example 5, 0.5 μm in example 6, 0.4 μm in example 7, and 0.6 μm in example 8. It was confirmed that the fourth absolute value was 1.5 μm in comparative example 1, 1.1 μm in comparative example 2, and 0.9 μm in comparative example 3.

On the other hand, it was confirmed that the difference value of the spring width was 8.4 μm in example 1, 8.4 μm in example 2, 8.2 μm in example 3, and 7.0 μm in example 4. It was confirmed that the difference value of the spring width was 7.5 μm in example 5, 9.1 μm in example 6, 8.4 μm in example 7, and 9.7 μm in example 8. It was confirmed that the difference value of the spring width was 12.5 μm in comparative example 1, 13.7 μm in comparative example 2, and 14.3 μm in comparative example 3.

It was confirmed that the first standard value was 27.9% in example 1, 28.0% in example 2, 27.4% in example 3, and 23.1% in example 4. It was confirmed that the first standard value was 24.9% in example 5, 30.3% in example 6, 28.1% in example 7, and 32.3% in example 8. It was confirmed that the first standard value was 41.6% in comparative example 1, 45.6% in comparative example 2, and 47.5% in comparative example 3.

It was confirmed that the standard deviation of the spring width was 2.0 μm in example 1, 1.7 μm in example 2, 1.9 μm in example 3, and 1.4 μm in example 4. It was confirmed that the standard deviation of the spring width was 1.4 μm in example 5, 1.9 μm in example 6, 2.0 μm in example 7, and 2.1 μm in example 8. It was confirmed that the standard deviation of the spring width was 2.5 μm in comparative example 1, 2.6 μm in comparative example 2, and 2.6 μm in comparative example 3.

It was confirmed that the second standard value was 6.6% in example 1, 5.7% in example 2, 6.3% in example 3, and 4.7% in example 4. It was confirmed that the second standard value was 4.7% in example 5, 6.3% in example 6, 6.6% in example 7, and 7.1% in example 8. It was confirmed that the second standard value was 8.2% in comparative example 1, 8.5% in comparative example 2, and 8.5% in comparative example 3.

It was confirmed that the percentage of 3σ to the average value of the spring width was 17.8% in example 1, 16.0% in example 2, 18.3% in example 3, and 13.0% in example 4. It was confirmed that the percentage of 3σ to the average value of the spring width was 13.0% in example 5, 18.1% in example 6, 18.3% in example 7, and 18.8% in example 8. It was confirmed that the percentage of 3σ to the average value of the spring widths was 24.8% in comparative example 1, 26.4% in comparative example 2, and 22.0% in comparative example 3.

It was confirmed that the variance of the spring width was 3.9 μm ² in example 1, 2.9 μm ² in example 2, 3.6 μm ² in example 3, and 2.0 μm ² in example 4. It was confirmed that the variance of the spring width was 2.0 μm ² in example 5, 3.6 μm ² in example 6, 4.0 μm ² in example 7, and 4.5 μm ² in example 8. It was confirmed that the variance of the spring width was 6.0 μm ² in comparative example 1, 6.5 μm ² in comparative example 2, and 6.6 μm ² in comparative example 3.

As described above, it was confirmed that the metal foils for spring members of examples 1 to 8 were smaller in all of the percentages and variances of the first standard value, standard deviation, second standard value, and 3σ with respect to the average value than those of the metal foils for spring members of comparative examples 1 to 3. Therefore, it can be said that the metal foils for spring members according to examples 1 to 8 can suppress variation in spring width in the thickness direction, as compared with the metal foils for spring members of comparative examples 1 to 3.

As shown in fig. 13, it was confirmed that, when the first absolute value was 0.15 μm or less, the difference value of the spring widths of the etching patterns was included in the range of 6.0 μm or more and 10.0 μm or less. In contrast, it was confirmed that, when the first absolute value was larger than 0.15 μm, the difference value of the spring widths of the etching patterns exceeded 12 μm. In this way, it was confirmed that the variation in the spring width of the etched pattern was significantly different with the 0.15 μm boundary in the first absolute value.

As shown in fig. 14, it was confirmed that, when the fourth absolute value was 0.8 μm or less, the difference value of the spring widths of the etching patterns was included in the range of 6.0 μm or more and 10.0 μm or less. On the other hand, it was confirmed that, when the fourth absolute value was larger than 0.85 μm, the difference value of the spring widths of the etching patterns exceeded 12 μm. In this way, it was confirmed that the deviation of the spring width of the etched pattern was large with the boundary of 0.8 μm in the fourth absolute value.

As shown in fig. 15, it was confirmed that, when the second absolute value was 0.15 μm ² or less, the difference value of the spring width of the etching pattern was included in the range of 6.0 μm or more and 10.0 μm or less. On the other hand, it was confirmed that when the second absolute value was larger than 0.15 μm ², the difference value of the spring widths of the etching patterns exceeded 12 μm. In this way, it was confirmed that the difference in spring width of the etched pattern was large with the boundary of 0.15 μm ² in the second absolute value.

As shown in fig. 16, it was confirmed that, when the third absolute value was 0.8 μm or less, the difference value of the spring widths of the etching patterns was included in the range of 6.0 μm or more and 10.0 μm or less. On the other hand, it was confirmed that, when the third absolute value was larger than 0.8 μm, the difference value of the spring widths of the etching patterns exceeded 12 μm. In this way, it was confirmed that the third absolute value was large in the variation of the spring width of the etched pattern with the 0.8 μm boundary.

As described above, according to the metal foil for a spring member, the method for manufacturing the metal foil for a spring member, and one embodiment of the spring member for an electronic device, the following effects can be obtained.

(1) The metal foil 10 satisfies the condition 1, and therefore, variation in thickness in the metal foil 10 can be suppressed. Therefore, in the spring member 20 formed by wet etching of the metal foil 10, variation in the spring width in the thickness direction can be suppressed.

(2) The metal foil 10 satisfies at least one of the conditions 2 to 5, and therefore, the variation in the thickness of the metal foil 10 can be suppressed. Therefore, the variation in width can be suppressed in the thickness direction of the spring member 20 formed by wet etching of the metal foil 10.

(3) The metal foil 10 can have a high hardness, and thus the durability of the spring member 20 formed from the metal foil 10 can be improved.

Claims

1. A metal foil for a spring member for manufacturing a spring member, wherein,

Comprises a first region having a square shape with a side length of 300mm for forming the spring member,

In the region of the first plate,

The absolute value of the difference value obtained by subtracting the standard deviation of the thickness in the width direction orthogonal to the rolling direction from the standard deviation of the thickness in the rolling direction is 0.15 [ mu ] m or less,

The maximum value of the thickness in the rolling direction is a first maximum value, the maximum value of the thickness in the width direction is a second maximum value, and the absolute value of the difference value obtained by subtracting the second maximum value from the first maximum value is 0.8 μm or less.

2. A metal foil for a spring member as claimed in claim 1, wherein,

In the first region, an absolute value of a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

3. A metal foil for a spring member as claimed in claim 1, wherein,

In the first region, a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less.

4. A metal foil for a spring member as claimed in claim 1, wherein,

In the first region, a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

5. A metal foil for a spring member as claimed in claim 1, wherein,

In the first region, a difference value obtained by subtracting a minimum value from a maximum value of the thickness in the rolling direction is a first difference value, a difference value obtained by subtracting a minimum value from a maximum value of the thickness in the width direction is a second difference value,

The absolute value of the difference value obtained by subtracting the second difference value from the first difference value is not more than 0.8 μm.

6. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

The absolute value of the difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less,

The difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less.

7. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

The difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

8. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

The difference value obtained by subtracting the minimum value from the maximum value of the thickness in the rolling direction is a first difference value, the difference value obtained by subtracting the minimum value from the maximum value of the thickness in the width direction is a second difference value,

9. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

A difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less,

10. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

11. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

A difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less,

12. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

13. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

14. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

15. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

16. A metal foil for a spring member as claimed in claim 1, wherein,

In the region of the first plate,

17. A metal foil for a spring member as claimed in any one of claims 1 to 16, wherein,

The metal foil for the spring member includes any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel tin copper, phosphor bronze, colsen alloy, and titanium copper.

18. A method of manufacturing a metal foil for a spring member, the metal foil for a spring member being used for manufacturing a spring member, comprising:

a step of rolling a base material; and

A step of separating the metal foil for the spring member from the plurality of rolled materials after preparing the plurality of rolled materials obtained by rolling the base material,

In the rolled material, a region having a square shape with a side length of 300mm and used for forming the spring member is a first region,

In the first region, the maximum value of the thickness in the rolling direction is a first maximum value, the maximum value of the thickness in the width direction orthogonal to the rolling direction is a second maximum value,

In the step of sorting the metal foil for spring members, the rolled material having an absolute value of a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction in the first region of 0.15 μm or less and an absolute value of a difference value obtained by subtracting the second maximum value from the first maximum value of 0.8 μm or less is sorted from the plurality of rolled materials as the metal foil for spring members.

19. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The sorting conditions for the spring member metal foil further include: in the first region, an absolute value of a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

20. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include: in the first region, a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less.

21. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include: in the first region, a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

22. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include: the absolute value of the difference value obtained by subtracting the second difference value from the first difference value is not more than 0.8 μm.

23. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

In the first region, an absolute value of a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less; and

24. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

25. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

26. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

In the first region, a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less; and

27. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

28. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

in the first region, a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less; and

29. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

In the first region, an absolute value of a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less;

30. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

31. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

32. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

In the first region, a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less;

33. The method for producing a metal foil for a spring member according to claim 18, wherein,

In the step of sorting the metal foil for spring members,

The conditions for sorting the spring member metal foil include:

34. A method for producing a metal foil for a spring member as claimed in any one of claims 18 to 33, wherein,

35. A spring member for an electronic device, which uses a metal foil for the spring member, wherein,

The absolute value of the difference value obtained by subtracting the standard deviation of the thickness of the metal foil for the spring member in the width direction orthogonal to the rolling direction from the standard deviation of the thickness in the rolling direction is 0.15 [ mu ] m or less,

In the metal foil for a spring member, the maximum value of the thickness in the rolling direction is a first maximum value, the maximum value of the thickness in the width direction is a second maximum value, and an absolute value of a difference value obtained by subtracting the second maximum value from the first maximum value is 0.8 μm or less.

36. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member, an absolute value of a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

37. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member, a difference value obtained by subtracting the standard deviation of the thickness in the width direction from the standard deviation of the thickness in the rolling direction is 0.15 μm or less.

38. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member, a difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm ² or less.

39. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member, a difference value obtained by subtracting a minimum value from a maximum value of the thickness in the rolling direction is a first difference value, a difference value obtained by subtracting a minimum value from a maximum value of the thickness in the width direction is a second difference value,

40. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

41. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

42. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

43. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

44. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

45. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

46. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

47. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

48. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

The absolute value of the difference value obtained by subtracting the variance of the thickness in the width direction from the variance of the thickness in the rolling direction is 0.15 μm or less,

The absolute value of the difference value obtained by subtracting the second difference value from the first difference value is not more than 0.8 μm ².

49. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

50. The spring member for an electronic device according to claim 35, wherein,

In the metal foil for a spring member,

51. The spring member for an electronic device according to any one of claims 35 to 50, wherein,