Spring member, camera module, and electronic apparatus

Abstract

In the present invention, a first edge portion includes a first bottom portion, a first top portion, and a second bottom portion located between a first end portion and a second end portion in a second direction. In the second direction, the first top portion is located between the first bottom portion and the second bottom portion. In a first direction, the distance between the first top portion and the central axis of an inner spring extending along the second direction is shorter than the distance between the central axis and the first end portion and / or the distance between the central axis and the second end portion. In the first direction, the distance between the central axis and the first top portion is longer than the distance between the central axis and the first bottom portion and the distance between the central axis and the second bottom portion.

Description

Spring member, camera module, and electronic device

[0001] The present disclosure relates to a spring member, a camera module, and an electronic device.

[0002] Camera modules included in camera-equipped electronic devices such as tablet terminals and smartphones are equipped with drive mechanisms that enable autofocus and zoom. Known drive mechanisms include a lens drive system and a sensor drive system. A lens drive system drive mechanism includes a spring member that enables the position of the lens to be changed in the direction of the lens's optical axis. In contrast, a sensor drive system drive mechanism includes a spring member that enables the position of the image sensor to be changed in the direction of the lens's optical axis (see, for example, Patent Documents 1 and 2).

[0003] JP 2014-059345 A JP 2020-170170 A

[0004] The springs included in the spring member are required to have a spring width with high uniformity in the thickness direction.

[0005] A spring member for solving the above problem includes a first surface, a second surface opposite to the first surface, and a plurality of springs arranged along a first direction in a cross section perpendicular to the first surface, the plurality of springs including a pair of outer springs and an inner spring sandwiched between the outer springs in the first direction. The direction perpendicular to the first direction is a second direction. The inner springs include a first edge and a second edge that face each other in the first direction. The first edge includes a first end located on the first surface and a second end located on the second surface, and a first bottom, a first apex, and a second bottom located between the first end and the second end in the second direction. In the second direction, the first apex is located between the first bottom and the second bottom. In the first direction, the distance between a central axis of the inner spring extending along the second direction and the first apex is shorter than at least one of the distance between the central axis and the first end and the distance between the central axis and the second end, and in the first direction, the distance between the central axis and the first apex is longer than the distance between the central axis and the first bottom and the distance between the central axis and the second bottom.

[0006] The spring member is formed by wet-etching a metal foil for the spring member from both the first and second surfaces. Because wet etching of the metal foil proceeds isotropically, the first and second edges of the inner spring formed on the metal foil by wet etching have an arc shape with a center of curvature outside the inner spring. Therefore, the inner spring has a constricted shape between the first and second surfaces. This tends to increase the difference between the spring width on each surface and the spring width at the constricted portion. In this regard, with the spring member described above, the first edge of the inner spring has a first bottom, a first top, and a second bottom. This makes it possible to reduce the amount of constriction at each bottom compared to when the inner spring is constricted at one point in the thickness direction. This allows for increased uniformity of the spring width in the thickness direction of the inner spring.

[0007] In the above spring member, the second edge portion includes a third end portion located on the first surface, a fourth end portion located on the second surface, and a third bottom portion, a second apex portion, and a fourth bottom portion located between the third end portion and the fourth end portion in the second direction, and in the second direction, the second apex portion is located between the third bottom portion and the fourth bottom portion, and in the first direction, the distance between the central axis extending along the second direction and the second apex portion is shorter than at least one of the distance between the central axis and the third end portion and the distance between the central axis and the fourth end portion, and in the first direction, the distance between the central axis and the second apex portion is longer than the distance between the central axis and the third bottom portion and the distance between the central axis and the fourth bottom portion.

[0008] According to the above spring member, in addition to the first edge portion, the second edge portion has a third bottom portion, a second top portion, and a fourth bottom portion, so it is possible to further improve the thickness uniformity of the inner spring compared to when only the first edge portion has two bottom portions and a top portion sandwiched between the two bottom portions.

[0009] In the above spring member, in the second direction, the distance between the first top and the second top may be shorter than the distance between the first top and the third bottom and the distance between the first top and the fourth bottom.

[0010] According to the spring member, the inner spring is likely to have a maximum value in the spring width between the first apex and the second apex in the second direction, which makes it difficult for the inner spring to have a narrowed shape at only one point in the thickness direction, thereby reducing the variation in the spring width in the thickness direction of the inner spring.

[0011] In the above spring member, in the second direction, the distance between the first top and the second top may be shorter than the distance between the second top and the first bottom and the distance between the second top and the second bottom.

[0012] In the above spring member, the width of the inner spring along the first direction may have a maximum value at the first peak, the second peak, or between the first peak and the second peak in the second direction.

[0013] In the above spring member, in the second direction, the width of the inner spring may have a first minimum value between the first end and the first apex, and a second minimum value between the second end and the first apex, and the percentage of the first minimum value to the maximum value and the percentage of the second minimum value to the maximum value may be 66% or more.

[0014] According to the above spring member, the outer shape of the inner spring approaches a rectangular shape, so that the strength of the inner spring can be increased.

[0015] In the above spring member, the width of the inner spring may have a first minimum value between the first end and the first apex and a second minimum value between the second end and the first apex, and in the second direction, the percentage of the distance between the maximum value and the first minimum value with respect to the thickness of the inner spring and the percentage of the distance between the maximum value and the second minimum value with respect to the thickness of the inner spring may be 24% or less.

[0016] According to the above spring member, the position where the width of the inner spring in the first direction becomes narrower is closer to the first apex, so that the resistance of the inner spring to deformation can be increased.

[0017] In the above spring member, in the second direction, the width of the inner spring has a first minimum value between the first end and the first apex, and a second minimum value between the second end and the first apex, and the percentage of the distance between the first minimum value and the second minimum value with respect to the thickness of the inner spring in the second direction may be 39% or more and 46% or less.

[0018] According to the above spring member, the shape of the inner spring is less likely to become biased in the second direction, so that the strength of the inner spring can be further increased.

[0019] In the spring member, the thickness of the inner spring may be 150 μm or more. Generally, the thicker the metal foil, the more the metal foil is eroded along the width direction of the spring when wet-etched, which makes the inner spring more likely to become constricted. In this regard, according to the spring member, even when a thick spring having a thickness of 150 μm or more is manufactured by wet-etching the metal foil, the difference between the minimum and maximum spring widths in the thickness direction is prevented from becoming large.

[0020] In the spring member, the pitch of the plurality of springs may be 100 μm or more and 200 μm or less, and the maximum width of each spring along the first direction may be ½ or less of the pitch.

[0021] In the spring member, the etching amount of the metal foil is so large in the first direction that more than half of the metal foil is etched near the spring, which tends to result in noticeable narrowing of the inner spring, thereby significantly achieving the effect of the inner spring having the first edge portion.

[0022] In the above-described spring member, the spring member comprises a base material including any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium-copper, the base material having a first surface and a second surface located opposite the first surface of the base material, and the spring member may further comprise a copper layer on at least one of the first surface of the base material and the second surface of the base material.

[0023] A camera module for solving the above problem includes the spring member. An electronic device for solving the above problem includes the camera module.

[0024] According to the spring member of the present disclosure, the uniformity of the spring width in the thickness direction of the inner spring can be improved.

[0025] FIG. 1 is a plan view showing the structure of a spring member of one embodiment. FIG. 2 is a cross-sectional view showing the structure along line II-II shown in FIG. 1. FIG. 3 is a cross-sectional view showing the structure of an inner spring provided in the spring member shown in FIG. 2. FIG. 4 is a process diagram showing one step in a method for manufacturing a spring member. FIG. 5 is a process diagram showing one step in a method for manufacturing a spring member. FIG. 6 is a process diagram showing one step in a method for manufacturing a spring member. FIG. 7 is a process diagram showing one step in a method for manufacturing a spring member. FIG. 8 is a process diagram showing one step in a method for manufacturing a spring member. FIG. 9 is a process diagram showing one step in a method for manufacturing a spring member in Test Example 3. FIG. 10 is a process diagram showing one step in a method for manufacturing a spring member in Test Example 3. FIG. 11 is a process diagram showing one step in a method for manufacturing a spring member in Test Example 3. FIG. 12 is a process diagram showing one step in a method for manufacturing a spring member in Test Example 5. FIG. 13 is a process diagram showing one step in a method for manufacturing a spring member in Test Example 5. Fig. 14 is a process diagram showing one step in the manufacturing method of the spring member in Test Example 5. Fig. 15 is a table showing the evaluation results of Test Example 1. Fig. 16 is a table showing the evaluation results of Test Example 2. Fig. 17 is a table showing the evaluation results of Test Example 3. Fig. 18 is a table showing the evaluation results of Test Example 4. Fig. 19 is a table showing the analysis results of Test Example 1. Fig. 20 is a table showing the analysis results of Test Example 2. Fig. 21 is a table showing the analysis results of Test Example 3. Fig. 22 is a table showing the analysis results of Test Example 4.

[0026] An embodiment of the spring member will be described with reference to Figures 1 to 22. [Spring Member] The spring member will be described with reference to Figures 1 to 3. As shown in Figure 1, a spring member 10 for a camera module has a first surface 10S1 and a second surface 10S2 opposite to the first surface 10S1. The spring member 10 has an outer frame portion 11, an inner frame portion 12, and a spring portion 13. The spring portion 13 is a leaf spring.

[0027] The spring portion 13 includes a plurality of springs 13A. When viewed from a viewpoint opposite to the plane in which the spring member 10 extends, each spring 13A has a linear shape extending along the plane in which the spring member 10 extends. Each spring 13A is a part of the metal foil that forms the spring member 10, and adjacent springs 13A are connected to each other by bent portions.

[0028] In the example shown in FIG. 1 , the outer frame portion 11 has an octagonal outer shape, and the inner frame portion 12 has a circular outer shape. The spring portion 13 has a folded line shape. The outer shapes of the outer frame portion 11 and the inner frame portion 12 may be changed depending on the shapes of other components included in the drive mechanism of the camera module in which the spring member 10 is mounted, i.e., components other than the spring member 10. The spring portion 13 may have a structure in which a single wire has multiple bends, making it appear as if multiple springs 13A are lined up, or may have a structure in which multiple springs 13A that are independent of each other are lined up. The inner frame portion 12 is located within the area defined by the outer frame portion 11. The spring portion 13 connects the inner frame portion 12 to the outer frame portion 11.

[0029] In a lens drive type drive mechanism, a spring member 10 is arranged on one side of the lens in the optical axis direction of the lens. Alternatively, two spring members 10 are arranged to sandwich the lens in the optical axis direction of the lens. In the optical axis direction, the position of the inner frame portion 12 connected to each outer frame portion 11 changes relative to that outer frame portion 11, thereby changing the position of the lens in the optical axis direction. This makes it possible to correct camera shake using a lens drive type drive mechanism.

[0030] In contrast, in a sensor-driven drive mechanism, a spring member 10 is arranged on one side of the image sensor in the optical axis direction of the lens. Alternatively, two spring members 10 are arranged to sandwich the image sensor in the optical axis direction of the lens. In the optical axis direction, the position of the inner frame portion 12 connected to each outer frame portion 11 changes relative to that outer frame portion 11, thereby changing the position of the image sensor in the optical axis direction of the lens. This makes it possible to correct camera shake using a sensor-driven drive mechanism.

[0031] The electronic device in which the camera module including the spring member 10 is mounted may be, for example, a mobile phone terminal, a smartphone, a tablet terminal, or a notebook personal computer.

[0032] Fig. 2 shows the cross-sectional structure of the spring portion 13 along line II-II shown in Fig. 1. That is, Fig. 2 shows the cross-sectional structure of the spring member 10 along a plane that is perpendicular to the first surface 10S1 of the spring member 10 and perpendicular to the direction in which each spring 13A extends.

[0033] As shown in FIG. 2 , in a cross section perpendicular to the first surface 10S1, the spring portion 13 includes three or more springs 13A. In this cross section, the springs 13A located at both ends in the direction in which the springs 13A are arranged are outer springs 13A1. The direction in which the springs 13A are arranged is the first direction D1. Of the multiple springs 13A, the spring 13A sandwiched between the outer springs 13A1 in the first direction D1 is the inner spring 13A2. That is, in a cross section perpendicular to the first surface 10S1, the spring portion 13 includes multiple springs 13A arranged along the first direction D1. The multiple springs 13A include a pair of outer springs 13A1 and an inner spring 13A2 sandwiched between the outer springs 13A1 in the first direction D1.

[0034] 2, in a cross section perpendicular to the first surface 10S1, the spring portion 13 includes six springs 13A. Therefore, in the first direction D1, four inner springs 13A2 are sandwiched between two outer springs 13A1. The multiple springs 13A are arranged at approximately equal intervals in the first direction D1.

[0035] The width of each spring 13A at the first surface 10S1 is a first width WS1. The width of each spring 13A at the second surface 10S2 is a second width WS2. The inner spring 13A2 has a width of 10 μm or more at the first surface 10S1 and the second surface 10S2. The first width WS1 of the inner spring 13A2 is 10 μm or more, and the second width WS2 is 10 μm or more.

[0036] The outer spring 13A1 has a width equal to that of the inner spring 13A2 on the first surface 10S1 and the second surface 10S2. The outer spring 13A1 may have a width greater than that of the inner spring 13A2.

[0037] The thickness of the spring member 10 may be 150 μm or more. The thickness of the spring member 10 is the distance between the first surface 10S1 and the second surface 10S2. That is, the thickness of the inner spring 13A2 may be 150 μm or more.

[0038] The distance between the centers of the springs 13A in the direction in which the springs 13A are arranged is the pitch P of the springs 13A. The pitch P may be the distance between the centers of the springs 13A on the first surface 10S1 or the distance between the centers of the springs 13A on the second surface 10S2. In either case, the pitch P has the same value. The pitch P may be, for example, 100 μm or more and 200 μm or less.

[0039] The spring member 10 is formed from a metal having a high enough hardness to realize the spring load or deflection required for the spring member 10. The spring member 10 may be formed from, 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 strip for springs." The copper alloy may be, for example, a copper alloy specified in JIS H 3130:2018 "Beryllium copper, titanium copper, phosphor bronze, nickel-tin copper, and nickel silver plate and strip for springs."

[0040] The spring member 10 may include any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium-copper. The spring member 10 is preferably formed from any one selected from the above group. Since the spring member 10 can have high hardness, the durability of the spring member 10 can be increased.

[0041] Fig. 3 shows an enlarged cross-sectional structure of one of the inner springs 13A2 included in the spring member 10. In the example shown in Fig. 3, the inner spring 13A2 has an axisymmetric shape with respect to the central axis 13AA of the inner spring 13A2.

[0042] 3, the direction perpendicular to the first direction D1 is the second direction D2. The inner spring 13A2 has a first edge 13E1 and a second edge 13E2 that face each other in the first direction D1.

[0043] The first edge portion 13E1 includes a first end E1 located on the first surface 10S1, a second end E2 located on the second surface 10S2, and a first bottom B1, a first peak T1, and a second bottom B2 located between the first end E1 and the second end E2 in the second direction D2. In the second direction D2, the first peak T1 is located between the first bottom B1 and the second bottom B2.

[0044] The first edge 13E1 has a folded line shape with three bending points: a first bottom B1, a first apex T1, and a second bottom B2. Of the first bottom B1 and the second bottom B2, the bottom closest to the first end E1 is the first bottom B1, and the bottom closest to the second end E2 is the second bottom B2.

[0045] In the example shown in FIG. 3 , the first line segment connecting the first end E1 and the first bottom B1, the second line segment connecting the first bottom B1 and the first apex T1, the third line segment connecting the first apex T1 and the second bottom B2, and the fourth line segment connecting the second bottom B2 and the second end E2 are all straight. At least one of the first, second, third, and fourth line segments may be curved. If each line segment is curved, it may have an arc shape whose center of curvature is located outside the inner spring 13A2. That is, each line segment may have an arc shape that is recessed toward the central axis 13AA. Alternatively, it may have an arc shape whose center of curvature is located within the inner spring 13A2. That is, each line segment may have an arc shape that bulges outward from the central axis 13AA.

[0046] The central axis 13AA of the inner spring 13A2 may be an axis that passes through the center of the inner spring 13A2 on the first surface 10S1 and extends along the second direction D2, or it may be an axis that passes through the center of the inner spring 13A2 on the second surface 10S2 and extends along the second direction D2.

[0047] In the first direction D1, the distance DT1 between the central axis 13AA of the inner spring 13A2 extending along the second direction D2 and the first apex T1 is shorter than the distance DE1 between the central axis 13AA and the first end E1 and the distance DE2 between the central axis 13AA and the second end E2. In the first direction D1, the distance DT1 between the central axis 13AA and the first apex T1 is longer than the distance DB1 between the central axis 13AA and the first bottom B1 and the distance DB2 between the central axis 13AA and the second bottom B2.

[0048] In other words, in the first direction D1, the amount by which the first edge 13E1 at the first apex T1 protrudes from the central axis 13AA is smaller than the amount by which the first end E1 and the second end E2 protrude from the central axis 13AA. Also, in the first direction D1, the amount by which the first edge 13E1 at the first apex T1 protrudes from the central axis 13AA is greater than the amount by which the first bottom B1 and the second bottom B2 protrude from the central axis 13AA.

[0049] The spring member 10 is formed by wet-etching a metal foil for the spring member from both the first and second surfaces. Because wet etching of the metal foil progresses isotropically, the first and second edges of the inner spring formed on the metal foil by wet etching have an arc shape with a center of curvature outside the inner spring. Therefore, the inner spring has a constricted shape between the first and second surfaces. This tends to increase the difference between the spring width on each surface and the spring width at the constricted portion. In this regard, according to the spring member 10 of the present disclosure, the first edge 13E1 of the inner spring 13A2 has a first bottom B1, a first peak T1, and a second bottom B2. This makes it possible to reduce the amount of constriction at each bottom B1, B2 compared to when the inner spring 13A2 is constricted at a single point in the thickness direction. This allows for increased uniformity of the spring width in the thickness direction of the inner spring 13A2.

[0050] The distance DT1 may be, for example, 10 μm or more and 20 μm or less. The distances DE1 and DE2 may be, for example, 16 μm or more and 25 μm or less. The distances DB1 and DB2 may be, for example, 5 μm or more and 15 μm or less.

[0051] The second edge portion 13E2 includes a third end E3 located on the first surface 10S1, a fourth end E4 located on the second surface 10S2, and a third bottom B3, a second apex T2, and a fourth bottom B4 located between the third end E3 and the fourth end E4 in the second direction D2. The second apex T2 is located between the third bottom B3 and the fourth bottom B4 in the second direction D2.

[0052] The second edge 13E2 has a folded line shape with three bending points: a third bottom B3, a second top T2, and a fourth bottom B4. Of the third bottom B3 and the fourth bottom B4, the third bottom B3 is the bottom closest to the third end E3, and the fourth bottom B4 is the bottom closest to the fourth end E4.

[0053] In the example shown in FIG. 3 , the first line segment connecting the third end E3 and the third bottom B3, the second line segment connecting the third bottom B3 and the second apex T2, the third line segment connecting the second apex T2 and the fourth bottom B4, and the fourth line segment connecting the fourth bottom B4 and the fourth end E4 are all straight. At least one of the first, second, third, and fourth line segments may be curved. If each line segment is curved, it may have an arc shape whose center of curvature is located outside the inner spring 13A2. That is, each line segment may have an arc shape that is recessed toward the central axis 13AA. Alternatively, it may have an arc shape whose center of curvature is located within the inner spring 13A2. That is, each line segment may have an arc shape that bulges outward from the central axis 13AA.

[0054] In the first direction D1, the distance DT2 between the central axis 13AA extending along the second direction D2 and the second apex T2 is shorter than the distance DE3 between the central axis 13AA and the third end E3 and the distance DE4 between the central axis 13AA and the fourth end E4. In the first direction D1, the distance DT2 between the central axis 13AA and the second apex T2 is longer than the distance DB3 between the central axis 13AA and the third bottom B3 and the distance DB4 between the central axis 13AA and the fourth bottom B4.

[0055] In other words, in the first direction D1, the amount by which the second edge 13E2 at the second apex T2 protrudes relative to the central axis 13AA is smaller than the amount by which the third end E3 and the fourth end E4 protrude relative to the central axis 13AA. Also, in the first direction D1, the amount by which the second edge 13E2 at the second apex T2 protrudes relative to the central axis 13AA is greater than the amount by which the third bottom B3 and the fourth bottom B4 protrude relative to the central axis 13AA.

[0056] In addition to the first edge 13E1, the second edge 13E2 has a third bottom B3, a second peak T2, and a fourth bottom B4. This makes it possible to further improve the uniformity of the spring width of the inner spring 13A2 compared to when only the first edge 13E1 has two bottoms and a first peak sandwiched between the two bottoms.

[0057] The distance DT2 may be, for example, 10 μm or more and 20 μm or less. The distances DE3 and DE4 may be, for example, 16 μm or more and 25 μm or less. The distances DB3 and DB2 may be, for example, 5 μm or more and 15 μm or less.

[0058] In the second direction D2, the distance between the first apex T1 and the second apex T2 may be shorter than the distance between the first apex T1 and the third bottom B3 and the distance between the first apex T1 and the fourth bottom B4. In this case, the inner spring 13A2 is likely to have a maximum value in spring width between the first apex T1 and the second apex T2 in the second direction D2. This makes it less likely that the inner spring 13A2 will have a constricted shape in only one location in the thickness direction, thereby reducing variation in the spring width of the inner spring 13A2 in the thickness direction.

[0059] In the second direction D2, the distance between the first apex T1 and the second apex T2 may be, for example, 0 μm or more and 10 μm or less. In the second direction D2, the distance between the first apex T1 and the third bottom B3 may be, for example, 15 μm or more and 30 μm or less. In the second direction D2, the distance between the first apex T1 and the fourth bottom B4 may be, for example, 15 μm or more and 30 μm or less.

[0060] In the second direction D2, the distance between the first apex T1 and the second apex T2 may be shorter than the distance between the second apex T2 and the first bottom B1 and the distance between the second apex T2 and the second bottom B2. In this case, the inner spring 13A2 is likely to have a maximum value in spring width between the first apex T1 and the second apex T2 in the second direction D2. This makes it less likely that the inner spring 13A2 will have a constricted shape in only one location in the thickness direction, thereby reducing variation in the spring width of the inner spring 13A2 in the thickness direction.

[0061] In the second direction D2, the distance between the first apex T1 and the second apex T2 may be, for example, 0 μm or more and 10 μm or less. In the second direction D2, the distance between the second apex T2 and the first bottom B1 may be, for example, 15 μm or more and 30 μm or less. In the second direction D2, the distance between the second apex T2 and the second bottom B2 may be, for example, 15 μm or more and 30 μm or less.

[0062] From the viewpoint of increasing the maximum value of the width W13A2 of the inner spring 13A2 along the first direction D1 between the first end E1 and the second end E2, it is preferable that the deviation between the positions of the first apex T1 and the second apex T2 in the second direction D2 be small. Furthermore, from the viewpoint of increasing the maximum value of the width W13A2 of the inner spring 13A2 along the first direction D1 between the first end E1 and the second end E2, it is more preferable that the positions of the first apex T1 and the second apex T2 be equal to each other.

[0063] Furthermore, from the viewpoint of reducing the number of bending points in the inner spring 13A2, it is preferable that the deviation between the position of the first bottom B1 and the position of the third bottom B3 in the second direction D2 is small, and it is also preferable that the position of the first bottom B1 and the position of the third bottom B3 are equal.

[0064] The width W13A2 of the inner spring 13A2 along the first direction D1 may have a maximum value at the first vertex T1 or the second vertex T2, so that the inner spring 13A2 does not have a constricted shape at only one point in the thickness direction, thereby reducing variation in the spring width of the inner spring 13A2 in the thickness direction.

[0065] The width W13A2 of the inner spring 13A2 has a maximum value on either the first surface 10S1 or the second surface 10S2. From the viewpoint of increasing the rigidity of the inner spring 13A2, the percentage of the local maximum value of the width W13A2 of the inner spring 13A2 with respect to the maximum value may be, for example, 45% or more, preferably 60% or more, and more preferably 75% or more.

[0066] In the spring member 10, the distance between the first apex T1 and the second apex T2 in the second direction D2 may be shorter than the distance between the second apex T2 and the first bottom B1 and the distance between the second apex T2 and the second bottom B2. In addition, in the spring member 10, the width of the inner spring 13A2 along the first direction D1 may have a maximum value at the first apex T1, the second apex T2, or between the first apex T1 and the second apex T2 in the second direction D2.

[0067] In addition, in the second direction D2, the width of the inner spring 13A2 may have a first minimum value between the first end E1 and the first apex T1 and a second minimum value between the second end E2 and the first apex T1. In the spring member 10, the percentage of the first minimum value to the maximum value and the percentage of the second minimum value to the maximum value may be 66% or more. This makes the outer shape of the inner spring 13A2 closer to a rectangular shape, thereby increasing the strength of the inner spring 13A2.

[0068] In the spring member 10, the percentage of the distance between the maximum value and the first minimum value with respect to the thickness of the inner spring 13A2 in the second direction D2 and the percentage of the distance between the maximum value and the second minimum value with respect to the thickness of the inner spring 13A2 may be 24% or less. This causes the position of the inner spring 13A2 where the width along the first direction D1 becomes narrower to be closer to the first peak T1, thereby increasing the resistance to deformation of the inner spring 13A2.

[0069] In the spring member 10, the percentage of the distance between the first and second minimum values ​​with respect to the thickness of the inner spring 13A2 in the second direction D2 may be 39% or more and 46% or less, which makes it difficult for the shape of the inner spring 13A2 to become uneven in the second direction D2, thereby further increasing the strength of the inner spring 13A2.

[0070] As described above, the thickness of the inner spring 13A2 may be, for example, 150 μm or more. The thicker the metal foil, the more the metal foil is eroded along the width direction of the spring 13A when wet-etched, which makes the inner spring 13A2 more likely to become constricted. In this regard, according to the spring member 10 of this embodiment, even when a thick spring 13A having a thickness of 150 μm or more is manufactured by wet-etching the metal foil, the difference between the minimum and maximum spring widths in the thickness direction is prevented from becoming large.

[0071] As described above, the pitch P among the multiple springs 13A may be, for example, 100 μm to 200 μm, and the maximum width of each spring 13A along the first direction D1 may be equal to or less than half the pitch. In this case, the amount of metal foil etching in the first direction D1 near the springs 13A is so large that more than half of the metal foil is etched, which tends to result in noticeable constriction of the inner spring 13A2. Therefore, the effect of the inner spring 13A2 having the first edge portion 13E1 can be significantly obtained.

[0072] [Method of Manufacturing Spring Member] A method of manufacturing the spring member 10 will be described with reference to Figures 4 to 8. As shown in Figure 4, a metal foil 21 for the spring member 10 is prepared. The metal foil 21 includes a first surface 21S1 and a second surface 21S2 opposite to the first surface 21S1. The metal foil 21 may include, for example, any material selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium-copper. The thickness of the metal foil 21 may be, for example, 150 µm or more.

[0073] Next, a first resist layer R1 is formed on the first surface 21S1 of the metal foil 21, and a second resist layer R2 is formed on the second surface 21S2. Each of the resist layers R1 and R2 may be formed of a negative resist or a positive resist. Each of the resist layers R1 and R2 may be formed by coating, or by attaching a dry film resist to the metal foil 21.

[0074] 5, resist patterns are formed by exposing and developing each of the resist layers R1 and R2. Specifically, a first resist pattern RP1 having through holes RP1H is formed from the first resist layer R1, and a second resist pattern RP2 having through holes RP2H is formed from the second resist layer R2.

[0075] 6, the metal foil 21 is wet-etched from both the first surface 21S1 and the second surface 21S2 using the resist patterns RP1 and RP2. This forms a first recess 21R1 recessed from the first surface 21S1 and a second recess 21R2 recessed from the second surface 21S2 in the metal foil 21. Thereafter, the first resist pattern RP1 is peeled off from the first surface 21S1, and the second resist pattern RP2 is peeled off from the second surface 21S2.

[0076] As shown in FIG. 7 , a third resist pattern RP3 is formed on the first surface 21S1 of the metal foil 21, and a fourth resist pattern RP4 is formed on the second surface 21S2. In this process, a resist layer is first formed over the entire first surface 21S1 so as to conform to the inner surfaces of the first recesses 21R1, and a resist layer is then formed over the entire second surface 21S2 so as to conform to the inner surfaces of the second recesses 21R2. Subsequently, each resist layer is exposed and developed to form a third resist pattern RP3 and a fourth resist pattern RP4. The third resist pattern RP3 has a through hole RP3H located at the bottom of the first recess 21R1. The third resist pattern RP3 covers the side surface of the first recess 21R1. The fourth resist pattern RP4 has a through hole RP4H located at the bottom of the second recess 21R2. The fourth resist pattern RP4 covers the side surface of the second recess 21R2.

[0077] 8, the metal foil 21 is wet-etched from both the first surface 21S1 and the second surface 21S2 using the resist patterns RP3 and RP4. As a result, the first hole 21H1 is formed as the etching of the first recess 21R1 progresses, and the second hole 21H2 is formed as the etching of the second recess 21R2 progresses. Then, the first hole 21H1 is connected to the second hole 21H2, thereby forming the through-hole 21H penetrating the metal foil 21.

[0078] Each of the holes 21H1 and 21H2 has a generally elliptical shape in a cross section perpendicular to the first surface 21S1. The portion of the metal foil 21 between the two through holes 21H is an etching pattern 23A2. The etching pattern 23A2 corresponds to an inner spring 13A2 included in the spring member 10.

[0079] When wet etching is performed using the third resist pattern RP3 and the fourth resist pattern RP4, the resist patterns RP3 and RP4 have portions that extend along the side surfaces of the recesses 21R1 and 21R2. This facilitates anisotropic wet etching of the metal foil 21. That is, the resist patterns RP3 and RP4 make it easier for the etching solution to flow in the thickness direction, which facilitates etching of the metal foil 21 in the thickness direction.

[0080] According to this manufacturing method of the spring member 10, the inner spring 13A2 can be formed so that the first edge 13E1 and the second edge 13E2 of the inner spring 13A2 have three bends in the thickness direction. As a result, the inner spring 13A2 does not have a constricted shape near the center in the thickness direction, and therefore, etching of the metal foil 21 does not form an etching pattern 23A2 cut at the center in the thickness direction.

[0081] Furthermore, since each of the tops T1 and T2 does not protrude in the first direction D1 from the ends E1, E2, E3, and E4 that sandwich the tops T1 and T2 in the thickness direction, contact between the inner spring 13A2 and the adjacent spring 13A is prevented when the spring member 10 is in use.

[0082] The metal foil 21 for forming the spring member 10 may include a base material and a copper layer. The base material may include any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium-copper. The base material has a first surface and a second surface opposite to the first surface. The copper layer may be located on at least one of the first surface and the second surface of the base material. That is, the copper layer may be located on both the first surface and the second surface, or only on the first surface or only on the second surface. The copper layer may be formed by, for example, vacuum deposition, sputtering, wet plating, or the like.

[0083] In addition, when the metal foil 21 includes a base material and one or more copper layers, the spring member 10 also includes the base material and one or more copper layers. The base material of the spring member 10 is a part of the base material of the metal foil 21, and the copper layer included in the spring member 10 is a part of the copper layer included in the metal foil 21. The base material has a first surface and a second surface opposite to the first surface. The copper layer is located on at least one of the first surface and the second surface. In other words, the copper layer may be located on both the first surface and the second surface of the base material, or may be located only on the first surface or only on the second surface.

[0084] [Test Examples] Test examples will be described with reference to Figures 4 to 22. [Test Example 1] A titanium copper metal foil 21 having a thickness of 150 µm was prepared. Next, a first resist layer R1 was formed on a first surface 21S1 of the metal foil 21, and a second resist layer R2 was formed on a second surface 21S2 of the metal foil 21, using a negative dry film resist (RY-5110UT, manufactured by Resonac Corporation) having a thickness of 15 µm.

[0085] A first resist pattern RP1 was formed by exposing and developing the first resist layer R1. A second resist pattern RP2 was formed by exposing and developing the second resist layer R2. In this process, the widths of the through holes RP1H and RP2H in the resist patterns RP1 and RP2 were set to 30 μm in a cross section perpendicular to the surface of each resist pattern RP1 and RP2 and along the direction in which the etching patterns corresponding to the springs are arranged. The through holes RP1H and RP2H were formed at equal intervals in the direction in which the etching patterns are arranged so that the pitch P in the springs was 130 μm.

[0086] Subsequently, the metal foil 21 was etched using a ferric chloride solution, thereby forming first recesses 21R1 on the first surface 21S1 of the metal foil 21 and second recesses 21R2 on the second surface 21S2. Then, the first resist pattern RP1 was peeled off from the first surface 21S1, and the second resist pattern RP2 was peeled off from the second surface 21S2.

[0087] Next, resist layers having thicknesses of approximately 5 μm to 8 μm were formed by electrodeposition on the first surface 21S1 and the second surface 21S2 of the metal foil 21. A positive photoresist for plating (Honeyresist AP-1000-D, manufactured by Honey Chemical Co., Ltd.) was used. Each resist layer was then exposed and developed to form a third resist pattern RP3 on the first surface 21S1 and a fourth resist pattern RP4 on the second surface 21S2. Through holes RP3H and RP4H with a width of 38 μm were formed in each resist pattern RP3 and RP4. Furthermore, the through holes RP3H and RP4H were formed at equal intervals in the direction in which the etching patterns were aligned, so that the pitch P of the spring was 130 μm.

[0088] Thereafter, the metal foil 21 was etched using a ferric chloride solution, thereby forming a through hole 21H composed of a first hole portion 21H1 and a second hole portion 21H2 in the metal foil 21. As a result, the metal foil 21 having two etching patterns 23A2 was obtained.

[0089] [Test Example 2] In Test Example 1, the widths of the through holes RP1H in the first resist pattern RP1 and the through holes RP2H in the second resist pattern RP2 were changed to 20 μm, and the spring pitch P was changed to 120 μm. The widths of the through holes RP3H in the third resist pattern RP3 and the through holes RP4H in the fourth resist pattern RP4 were changed to 28 μm. Otherwise, the metal foil 21 of Test Example 2 was obtained by the same method as Test Example 1.

[0090] Test Example 3 will be described with reference to Figures 9 to 11. As shown in Figure 9, in Test Example 3, a titanium copper metal foil 21 having a thickness of 150 µm was prepared. Next, a first resist layer R1 was formed on a first surface 21S1 of the metal foil 21, and a second resist layer R2 was formed on a second surface 21S2. The titanium copper metal foil 21, first resist layer R1, and second resist layer R2 in Test Example 3 were the same as the metal foil 21, first resist layer R1, and second resist layer R2 in Test Example 1.

[0091] 10, resist patterns were formed by exposing and developing each of the resist layers R1 and R2. Specifically, a first resist pattern RP51 having through holes RP51H was formed from the first resist layer R1, and a second resist pattern RP52 having through holes RP52H was formed from the second resist layer R2. At this time, the width of the through holes RP51H and RP52H in each of the resist patterns RP51 and RP52 was set to 22 μm, and the through holes RP51H and RP52H were formed at equal intervals in the direction in which the etching patterns were arranged so that the spring pitch P was 130 μm.

[0092] 11 , the metal foil 21 was etched using a ferric chloride solution. As a result, through-holes 21H each consisting of a first hole portion 21H1 opening on the first surface 21S1 and a second hole portion 21H2 opening on the second surface 21S2 were formed in the metal foil 21. As a result, a metal foil 21 having an etching pattern 23A2 was obtained.

[0093] Test Example 4 In Test Example 3, the width of the through holes RP51H of the first resist pattern RP51 and the width of the through holes RP51H of the second resist pattern RP52 were changed to 12 μm, and the spring pitch P was changed to 120 μm. Otherwise, the metal foil 21 of Test Example 4 was obtained by the same method as Test Example 3.

[0094] Test Example 5 will be described with reference to Figures 12 to 14. As shown in Figure 12, in Test Example 5, a titanium copper metal foil 21 having a thickness of 150 µm was prepared. Next, a first resist layer R1 was formed on a first surface 21S1 of the metal foil 21, and a second resist layer R2 was formed on a second surface 21S2. The titanium copper metal foil 21, first resist layer R1, and second resist layer R2 in Test Example 5 were the same as the metal foil 21, first resist layer R1, and second resist layer R2 in Test Example 1.

[0095] 13, resist patterns were formed by exposing and developing each of the resist layers R1 and R2. Specifically, a first resist pattern RP61 having through holes RP61H was formed from the first resist layer R1, and a second resist pattern RP62 having through holes RP62H was formed from the second resist layer R2. At this time, the width of the through holes RP61H and RP62H of each of the resist patterns RP61 and RP62 was set to 38 μm, and the through holes RP61H and RP62H were formed at equal intervals in the direction in which the etching patterns were arranged so that the spring pitch P was 130 μm.

[0096] 14, the metal foil 21 was etched using a ferric chloride solution. As a result, through-holes 21H each consisting of a first hole portion 21H1 opening on the first surface 21S1 and a second hole portion 21H2 opening on the second surface 21S2 were formed in the metal foil 21. As a result, a metal foil 21 having an etching pattern 23A2 was obtained.

[0097] Test Example 6 In Test Example 5, the width of the through holes RP61H of the first resist pattern RP61 and the width of the through holes RP62H of the second resist pattern RP62 were set to 28 μm, and the spring pitch P was changed to 120 μm. Otherwise, the metal foil 21 of Test Example 6 was obtained by the same method as Test Example 5.

[0098] [Evaluation Method] A portion of the metal foil 21 of each Example and each Test Example, including two etching patterns, was cut out as a measurement sample. Subsequently, the measurement sample was embedded in resin to prepare an embedded sample. The embedded sample was cut using a microtome to form a cross section of the cross-sectional structure of the etching patterns along a plane perpendicular to the first surface 21S1.

[0099] An optical microscope (VHX-7000, manufactured by Keyence Corporation) was used to observe the cross section of the embedded sample, and the positions of each end, bottom, and top of each etching pattern in the XY coordinate system were measured. The magnification of the objective lens was set to 200x. The position of each part in the etching pattern was measured so that the thickness direction of the etching pattern was the Y coordinate and the width direction of the etching pattern was the X coordinate.

[0100] [Evaluation Results] The measurement results for each test example are as shown in Figures 15 to 18. In test examples 5 and 6, it was found that the etching pattern 23A2 formed on the metal foil 21 was cut partway through in the thickness direction, as shown in Figure 14. Therefore, the embedded samples of test examples 5 and 6 were not measured.

[0101] 15 to 18, for the Y coordinate, 2% of the measurement data was removed in both the direction from the first surface 21S1 to the second surface 21S2 and the direction from the second surface 21S2 to the first surface 21S1, and the minimum position in the direction from the first surface 21S1 to the second surface 21S2 was set to 0. Also, for the X coordinate, for the measurement results shown in FIGS. 15 to 18, the position at the first edge of the first etching pattern where the X coordinate value was smallest during measurement was set to 0. The first edge of the etching pattern corresponds to the first edge of the inner spring, and the second edge of the etching pattern corresponds to the second edge of the inner spring. For the second etching pattern, the position at the first edge where the X coordinate value was smallest during measurement was set to 0. In each example and each test example, the axis passing through the center of the etching pattern 23A2 on the second surface 21S2 and extending along the second direction is the central axis of the etching pattern 23A2.

[0102] 15 , in Test Example 1, at the first edge of the first etching pattern, the position of the second end was (0,145), the position of the second bottom was (8.8,109), the position of the first peak was (4.7,73), the position of the first bottom was (8.6,38), and the position of the first end was (2.2,0). Also, at the second edge, the position of the fourth end was (43.9,145), the position of the fourth bottom was (32.5,107), the position of the second peak was (35.6,76), the position of the third bottom was (29.9,38), and the position of the third end was (38.2,0).

[0103] The spring width was found to be 43.9 μm at the position where the Y coordinate was 145 μm, 23.7 μm at the position where the Y coordinate was 107 μm, 30.7 μm at the position where the Y coordinate was 74 μm, 21.3 μm at the position where the Y coordinate was 38 μm, and 35.9 μm at the position where the Y coordinate was 0 μm.

[0104] It was found that the spring width had minimum values ​​at the Y coordinate position of 107 μm and at the Y coordinate position of 38 μm, and had a maximum value at the Y coordinate position of 74 μm.

[0105] It was also found that, at the first edge of the second etching pattern, the position of the second end was (0,145), the position of the second bottom was (9.8,105), the position of the first top was (4.8,71), the position of the first bottom was (7.9,36), and the position of the first end was (0.3,0).It was also found that, at the second edge, the position of the fourth end was (42.7,145), the position of the fourth bottom was (30.7,98), the position of the second top was (32.9,78), the position of the third bottom was (28.0,39), and the position of the third end was (35.8,0).

[0106] The spring width was found to be 42.7 μm at the position where the Y coordinate was 145 μm, 21.1 μm at the position where the Y coordinate was 103 μm, 27.9 μm at the position where the Y coordinate was 71 μm, 20.1 μm at the position where the Y coordinate was 36 μm, and 35.5 μm at the position where the Y coordinate was 0 μm.

[0107] It was found that the spring width had minimum values ​​at the Y coordinate position of 103 μm and at the Y coordinate position of 36 μm, and had a maximum value at the Y coordinate position of 71 μm.

[0108] Thus, for each etching pattern in Test Example 1, it was found that, in the first direction D1, the amount by which the first apex of the first edge portion protruded relative to the central axis of the etching pattern was smaller than the amount by which each end portion protruded relative to the central axis, and larger than the amount by which each bottom portion protruded relative to the central axis. Furthermore, it was found that, in the first direction D1, the amount by which the second apex of the second edge portion protruded relative to the central axis of the etching pattern was smaller than the amount by which each end portion protruded relative to the central axis, and larger than the amount by which each bottom portion protruded relative to the central axis. In other words, it was found that the spring member manufacturing method in Test Example 1 can manufacture the above-described spring member 10. Note that, as long as the above-described spring member 10 can be manufactured, the manufacturing method of the spring member 10 is not limited to the manufacturing method of the spring member 10 in Test Example 1.

[0109] 16 , in Test Example 2, at the first edge of the first etching pattern, the position of the second end was (0,145), the position of the second bottom was (14.1,92), the position of the first peak was (12.2,75), the position of the first bottom was (14.2,41), and the position of the first end was (3.5,0). Also, at the second edge, the position of the fourth end was (39.7,145), the position of the fourth bottom was (29.6,101), the position of the second peak was (31.7,78), the position of the third bottom was (27.1,40), and the position of the third end was (36.6,0).

[0110] The spring width was found to be 39.7 μm at the position where the Y coordinate was 145 μm, 15.9 μm at the position where the Y coordinate was 100 μm, 19.4 μm at the position where the Y coordinate was 77 μm, 12.9 μm at the position where the Y coordinate was 41 μm, and 33.1 μm at the position where the Y coordinate was 0 μm.

[0111] It was found that the spring width had minimum values ​​at the Y coordinate position of 100 μm and at the Y coordinate position of 41 μm, and had a maximum value at the Y coordinate position of 77 μm.

[0112] It was also found that, at the first edge of the second etching pattern, the position of the second end was (0,145), the position of the second bottom was (11.3,102), the position of the first peak was (6.4,67), the position of the first bottom was (9.4,32), and the position of the first end was (4.6,0).It was also found that, at the second edge, the position of the fourth end was (40.5,145), the position of the fourth bottom was (28.0,102), the position of the second peak was (30.7,72), the position of the third bottom was (28.9,47), and the position of the third end was (39.1,0).

[0113] The spring width was found to be 40.5 μm at the position where the Y coordinate was 145 μm, 16.6 μm at the position where the Y coordinate was 102 μm, 24.1 μm at the position where the Y coordinate was 69 μm, 19.9 μm at the position where the Y coordinate was 39 μm, and 34.5 μm at the position where the Y coordinate was 0 μm.

[0114] It was found that the spring width had minimum values ​​at the Y coordinate position of 102 μm and at the Y coordinate position of 39 μm, and had a maximum value at the Y coordinate position of 69 μm.

[0115] Thus, for each etching pattern of Test Example 2, it was found that, in the first direction D1, the amount by which the first apex of the first edge portion protruded relative to the central axis of the etching pattern was smaller than the amount by which each end portion protruded relative to the central axis, and larger than the amount by which each bottom portion protruded relative to the central axis. Furthermore, it was found that, in the first direction D1, the amount by which the second apex of the second edge portion protruded relative to the central axis of the etching pattern was smaller than the amount by which each end portion protruded relative to the central axis, and larger than the amount by which each bottom portion protruded relative to the central axis. In other words, it was found that the spring member manufacturing method of Test Example 2 can manufacture the spring member 10. Note that, as long as the above-described spring member 10 can be manufactured, the manufacturing method of the spring member 10 is not limited to the manufacturing method of the spring member 10 of Test Example 2.

[0116] 17 , in Test Example 3, at the first edge of the first etching pattern, the position of the second end was (0,145), the position of the second bottom was (8.2,110), the position of the first peak was (6.9,89), the position of the first bottom was (13.3,39), and the position of the first end was (4.7,0). Also, at the second edge, the position of the fourth end was (44.9,145), the position of the fourth bottom was (29.9,111), the position of the second peak was (47.4,77), the position of the third bottom was (36.6,36), and the position of the third end was (41.9,0).

[0117] The spring width was found to be 44.9 μm at the position where the Y coordinate was 145 μm, 29.9 μm at the position where the Y coordinate was 111 μm, 39.4 μm at the position where the Y coordinate was 77 μm, 23.4 μm at the position where the Y coordinate was 39 μm, and 37.2 μm at the position where the Y coordinate was 0 μm.

[0118] It was found that the spring width had minimum values ​​at the Y coordinate position of 111 μm and at the Y coordinate position of 39 μm, and had a maximum value at the Y coordinate position of 77 μm.

[0119] It was also found that, at the first edge of the second etching pattern, the position of the second end was (2.4,145), the position of the second bottom was (9.6,117), the position of the first peak was (0,76), the position of the first bottom was (10.7,32), and the position of the first end was (4.1,0).It was also found that, at the second edge, the position of the fourth end was (49.1,145), the position of the fourth bottom was (41.7,115), the position of the second peak was (50.5,76), the position of the third bottom was (38.8,33), and the position of the third end was (44.6,0).

[0120] The spring width was found to be 46.7 μm at the position where the Y coordinate was 145 μm, 32.2 μm at the position where the Y coordinate was 116 μm, 50.5 μm at the position where the Y coordinate was 76 μm, 28.1 μm at the position where the Y coordinate was 33 μm, and 40.5 μm at the position where the Y coordinate was 0 μm.

[0121] It was found that the spring width had minimum values ​​at the Y coordinate position of 116 μm and at the Y coordinate position of 33 μm, and had a maximum value at the Y coordinate position of 76 μm.

[0122] Thus, in the first etching pattern of Test Example 3, in the first direction D1, the amount by which the first apex of the first edge portion protruded relative to the central axis of the etching pattern was smaller than the amount by which each end protruded relative to the central axis, while the amount by which the second apex of the second edge portion protruded relative to the central axis of the etching pattern was greater than the amount by which each end protruded relative to the central axis. Furthermore, in the second etching pattern, in the first direction D1, the amount by which the first apex of the first edge portion protruded relative to the central axis of the etching pattern was greater than the amount by which each end protruded relative to the central axis. Furthermore, in the second etching pattern, in the second edge portion, the amount by which the second apex of the second edge portion protruded relative to the central axis of the etching pattern was greater than the amount by which each end protruded relative to the central axis. Therefore, in the spring member of Test Example 3, the protruding apexes came into contact with each other during operation, thereby increasing the probability of damage to the spring member.

[0123] 18 , in Test Example 4, at the first edge of the first etching pattern, the position of the second end was (3.2, 145), the position of the second bottom was (5.4, 113), the position of the first peak was (0, 80), the position of the first bottom was (16.0, 35), and the position of the first end was (9.4, 0). Also, at the second edge, the position of the fourth end was (58.0, 145), the position of the fourth bottom was (51.0, 113), the position of the second peak was (58.1, 80), the position of the third bottom was (50.1, 33), and the position of the third end was (55.5, 0).

[0124] The spring width was found to be 54.8 μm at the position where the Y coordinate was 145 μm, 42.4 μm at the position where the Y coordinate was 113 μm, 50.1 μm at the position where the Y coordinate was 80 μm, 34.1 μm at the position where the Y coordinate was 33 μm, and 46.1 μm at the position where the Y coordinate was 0 μm.

[0125] It was found that the spring width had minimum values ​​at the Y coordinate position of 113 μm and at the Y coordinate position of 33 μm, and had a maximum value at the Y coordinate position of 80 μm.

[0126] It was also found that, at the first edge of the second etching pattern, the position of the second end was (0,145), the position of the second bottom was (4.0,118), the position of the first peak was (0.9,84), the position of the first bottom was (13.6,34), and the position of the first end was (6.8,0).It was also found that, at the second edge, the position of the fourth end was (50.3,145), the position of the fourth bottom was (40.5,106), the position of the second peak was (44.1,78), the position of the third bottom was (39.3,42), and the position of the third end was (50.5,0).

[0127] The spring width was found to be 50.3 μm at the position where the Y coordinate was 145 μm, 37.0 μm at the position where the Y coordinate was 110 μm, 43.1 μm at the position where the Y coordinate was 80 μm, 26.0 μm at the position where the Y coordinate was 39 μm, and 43.7 μm at the position where the Y coordinate was 0 μm.

[0128] It was found that the spring width had minimum values ​​at the Y coordinate position of 110 μm and at the Y coordinate position of 39 μm, and had a maximum value at the Y coordinate position of 80 μm.

[0129] Thus, in the first etching pattern of Test Example 4, it was found that, in the first direction D1, the first apex of the first edge portion protruded more from the central axis of the etching pattern than the ends of each edge protruded more from the central axis. Furthermore, it was found that, in the second edge portion, the second apex protruded more from the central axis of the etching pattern than the ends of each edge protruded more from the central axis. Furthermore, in the second etching pattern, it was found that, in the first direction D1, the first apex of the first edge portion protruded more from the central axis of the etching pattern than the ends of each edge protruded more from the central axis. Therefore, in the spring member of Test Example 4, the protruding apexes came into contact with each other during operation, increasing the probability of damage to the spring member.

[0130] The results of the analysis of the etching patterns of each test example will be described with reference to Figures 19 to 22. Note that, in the following, with respect to the width of the etching pattern, the minimum value between the first end E1 and the first apex T1 will be referred to as the first minimum value, and the minimum value between the second end E2 and the first apex T1 will be referred to as the second minimum value.

[0131] 19 to 22, L1 is the first distance, T is the thickness of the etching pattern, L2 is the second distance, Aw is the width of the etching pattern on the second surface 21S2, Bw is the second minimum value, Cw is the maximum value, Dw is the first minimum value, and Ew is the width of the etching pattern on the first surface 21S1.

[0132] 19, in the first etching pattern of Test Example 1, the first distance, which is the distance between the maximum value and each position on the Y coordinate, was found to be 71 μm on the second surface 21S2, 33 μm on the second minimum value, 36 μm on the first minimum value, and 74 μm on the first surface. Furthermore, the percentage of each first distance relative to the thickness of the etching pattern was found to be 47.3% on the second surface 21S2, 22.0% on the second minimum value, 24.0% on the first minimum value, and 49.3% on the first surface 21S1. Furthermore, the second distance, which is the distance between the first minimum value and the second minimum value on the Y coordinate, was found to be 69 μm. Furthermore, the percentage of the second distance relative to the thickness of the etching pattern was found to be 46.0%.

[0133] In the first etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was 100.0% on the second surface 21S2, 54.0% at the second minimum, 69.9% at the maximum, 48.5% at the first minimum, and 81.8% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was 122.3% on the second surface 21S2, 66.0% at the second minimum, 85.5% at the maximum, 59.3% at the first minimum, and 100.0% on the first surface 21S1. The percentage of the second minimum relative to the maximum was 77.2%. The percentage of the first minimum relative to the maximum was 69.4%.

[0134] In the second etching pattern of Test Example 1, the first distance was found to be 74 μm on the second surface 21S2, 32 μm at the second minimum, 35 μm at the first minimum, and 71 μm on the first surface 21S1. The percentages of each first distance relative to the thickness of the etching pattern were found to be 49.3% on the second surface 21S2, 21.3% at the second minimum, 23.3% at the first minimum, and 47.3% on the first surface 21S1. The second distance was found to be 67 μm. The percentage of the second distance relative to the thickness of the etching pattern was found to be 44.7%.

[0135] In the second etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was 100.0% on the second surface 21S2, 49.4% at the second minimum, 65.3% at the maximum, 47.1% at the first minimum, and 83.1% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was 120.3% on the second surface 21S2, 59.4% at the second minimum, 78.6% at the maximum, 56.6% at the first minimum, and 100.0% on the first surface 21S1. The width at the second minimum relative to the maximum was 75.6%. The width at the first minimum relative to the maximum was 72.0%.

[0136] 20 , in the first etching pattern of Test Example 2, the first distance was found to be 68 μm on the second surface 21S2, 23 μm at the second minimum, 36 μm at the first minimum, and 77 μm on the first surface 21S1. Furthermore, the percentage of each first distance relative to the thickness of the etching pattern was found to be 45.3% on the second surface 21S2, 15.3% at the second minimum, 24.0% at the first minimum, and 51.3% on the first surface 21S1. Furthermore, the second distance was found to be 59 μm. Furthermore, the percentage of the second distance relative to the thickness of the etching pattern was found to be 39.3%.

[0137] In the first etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was found to be 100.0% on the second surface 21S2, 40.1% at the second minimum, 48.9% at the maximum, 32.5% at the first minimum, and 83.4% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was found to be 119.9% ​​on the second surface 21S2, 48.0% at the second minimum, 58.6% at the maximum, 39.0% at the first minimum, and 100.0% on the first surface 21S1. The percentage of the width at the second minimum relative to the maximum was found to be 82.0%. The percentage of the width at the first minimum relative to the maximum was found to be 66.5%.

[0138] In the second etching pattern of Test Example 2, the first distance was found to be 76 μm on the second surface 21S2, 33 μm at the second minimum, 30 μm at the first minimum, and 69 μm on the first surface 21S1. The percentages of each first distance relative to the thickness of the etching pattern were found to be 50.7% on the second surface 21S2, 22.0% at the second minimum, 20.0% at the first minimum, and 46.0% on the first surface. The second distance was found to be 63 μm. The percentage of the second distance relative to the thickness of the etching pattern was found to be 42.0%.

[0139] In the second etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was found to be 100.0% on the second surface 21S2, 41.0% at the second minimum, 59.5% at the maximum, 49.1% at the first minimum, and 85.2% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was found to be 117.4% on the second surface 21S2, 48.1% at the second minimum, 69.9% at the maximum, 57.7% at the first minimum, and 100.0% on the first surface 21S1. The percentage of the width at the second minimum relative to the maximum was found to be 68.9%. The percentage of the width at the first minimum relative to the maximum was found to be 82.6%.

[0140] 21 , in the first etching pattern of Test Example 3, the first distance was found to be 68 μm on the second surface 21S2, 34 μm at the second minimum, 38 μm at the first minimum, and 77 μm on the first surface 21S1. Furthermore, the percentage of each first distance relative to the thickness of the etching pattern was found to be 45.3% on the second surface 21S2, 22.7% at the second minimum, 25.3% at the first minimum, and 51.3% on the first surface 21S1. Furthermore, the second distance was found to be 72 μm. Furthermore, the percentage of the second distance relative to the thickness of the etching pattern was found to be 48.0%.

[0141] In the first etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was found to be 100.0% on the second surface 21S2, 66.6% at the second minimum, 87.8% at the maximum, 52.1% at the first minimum, and 82.9% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was found to be 120.7% on the second surface 21S2, 80.4% at the second minimum, 105.9% at the maximum, 62.9% at the first minimum, and 100.0% on the first surface 21S1. The percentage of the width at the second minimum relative to the maximum was found to be 75.9%. The percentage of the width at the first minimum relative to the maximum was found to be 59.4%.

[0142] In the second etching pattern of Test Example 3, the first distance was found to be 69 μm on the second surface 21S2, 40 μm at the second minimum, 43 μm at the first minimum, and 76 μm on the first surface 21S1. The percentage of the first distance relative to the thickness of the etching pattern was found to be 46.0% on the second surface 21S2, 26.7% at the second minimum, 28.7% at the first minimum, and 50.7% on the first surface 21S1. The second distance was found to be 83 μm. The percentage of the second distance relative to the thickness of the etching pattern was found to be 55.3%.

[0143] In the second etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was 100.0% on the second surface 21S2, 69.0% at the second minimum, 108.1% at the maximum, 60.2% at the first minimum, and 86.7% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was 115.3% on the second surface 21S2, 79.5% at the second minimum, 124.7% at the maximum, 69.4% at the first minimum, and 100.0% on the first surface 21S1. The percentage of the width at the second minimum relative to the maximum was 63.8%. The percentage of the width at the first minimum relative to the maximum was 55.6%.

[0144] 22 , in the first etching pattern of Test Example 4, the first distance was found to be 65 μm on the second surface 21S2, 33 μm at the second minimum, 47 μm at the first minimum, and 80 μm on the first surface 21S1. Furthermore, the percentage of the first distance relative to the thickness of the etching pattern was found to be 48.3% on the second surface 21S2, 22.0% at the second minimum, 31.3% at the first minimum, and 53.3% on the first surface 21S1. Furthermore, the second distance was found to be 80 μm. Furthermore, the percentage of the second distance relative to the thickness of the etching pattern was found to be 58.3%.

[0145] In the first etching pattern, the percentage of the width at each position relative to the width on the second surface 21S2 was found to be 100.0% on the second surface 21S2, 66.6% at the second minimum, 87.8% at the maximum, 52.1% at the first minimum, and 82.9% on the first surface 21S1. The percentage of the width at each position relative to the width on the first surface 21S1 was found to be 120.7% on the second surface 21S2, 80.4% at the second minimum, 105.9% at the maximum, 62.9% at the first minimum, and 100.0% on the first surface 21S1. The percentage of the width at the second minimum relative to the maximum was found to be 75.9%. The percentage of the width at the first minimum relative to the maximum was found to be 59.4%.

[0146] In the second etching pattern of Test Example 4, the first distance was found to be 65 μm on the second surface 21S2, 30 μm at the second minimum, 41 μm at the first minimum, and 80 μm on the first surface 21S1. The percentage of the first distance relative to the thickness of the etching pattern was found to be 43.3% on the second surface 21S2, 20.0% at the second minimum, 27.3% at the first minimum, and 53.3% on the first surface 21S1. The second distance was found to be 71 μm. The percentage of the second distance relative to the thickness of the etching pattern was found to be 47.3%.

[0147] In the second etching pattern, the ratio of the width at each position to the width on the second surface 21S2 was 100.0% on the second surface 21S2, 69.0% at the second minimum, 108.1% at the maximum, 60.2% at the first minimum, and 86.7% on the first surface 21S1. The ratio of the width at each position to the width on the first surface 21S1 was 115.3% on the second surface, 79.5% at the second minimum, 124.7% at the maximum, 69.4% at the first minimum, and 100.0% on the first surface 21S1. The ratio of the width at the second minimum to the maximum was 63.8%. The ratio of the width at the first minimum to the maximum was 55.6%.

[0148] That is, it was found that the percentage of the first minimum value relative to the maximum value and the percentage of the second minimum value relative to the maximum value were both 66% or more in the etching patterns of Test Examples 1 and 2. In contrast, it was found that Test Examples 3 and 4 included etching patterns in which at least one of the percentage of the first minimum value relative to the maximum value and the percentage of the second minimum value relative to the maximum value was less than 66%.

[0149] In addition, it was found that the percentage of the first distance at the first minimum value relative to the thickness of the etching pattern and the percentage of the first distance at the second minimum value relative to the thickness of the etching pattern were both 24% or less in the etching patterns of Test Examples 1 and 2. In contrast, it was found that Test Examples 3 and 4 included etching patterns in which at least one of the percentage of the first distance at the first minimum value relative to the thickness of the etching pattern and the percentage of the first distance at the second minimum value relative to the thickness of the etching pattern exceeded 24%.

[0150] Furthermore, it was found that the percentage of the second distance relative to the etching pattern was within the range of 39% to 46% in the etching patterns of Test Examples 1 and 2. In contrast, it was found that the percentage of the second distance relative to the etching pattern was greater than 46% in the etching patterns of Test Examples 3 and 4.

[0151] As described above, one embodiment of the spring member can achieve the following effects: (1) Because the first edge 13E1 of the inner spring 13A2 has the first bottom B1, the first peak T1, and the second bottom B2, it is possible to reduce the amount of constriction at each of the bottoms B1 and B2 compared to when the inner spring 13A2 is constricted at one point in the thickness direction. This makes it possible to improve the uniformity of the spring width in the thickness direction of the inner spring 13A2.

[0152] (2) In addition to the first edge 13E1, the second edge 13E2 may have a third bottom B3, a second peak T2, and a fourth bottom B4. In this case, the uniformity of the spring width of the inner spring 13A2 can be improved compared to when only the first edge 13E1 has two bottoms and a peak sandwiched between the two bottoms.

[0153] (3) The inner spring 13A2 is likely to have a maximum spring width between the first apex T1 and the second apex T2 in the second direction D2. This makes it difficult for the inner spring 13A2 to have a narrowed shape in only one place in the thickness direction, thereby reducing the variation in the spring width in the thickness direction of the inner spring 13A2.

[0154] (4) The width of the inner spring 13A2 may have a maximum value at the first apex T1 or the second apex T2. In this case, the inner spring 13A2 does not have a narrowed shape at only one point in the thickness direction, and therefore, the variation in the spring width in the thickness direction of the inner spring 13A2 is reduced.

[0155] (5) Even if a thick spring 13A having a thickness of 150 μm or more is manufactured by wet etching the metal foil 21, the difference between the minimum and maximum values ​​of the spring width in the thickness direction can be prevented from becoming large.

[0156] (6) In the vicinity of the spring 13A, the amount of etching of the metal foil 21 in the first direction D1 is large enough to etch more than half of the metal foil 21, which tends to significantly constrict the inner spring 13A2. Therefore, the effect of the inner spring 13A2 having the first edge portion 13E1 can be significantly obtained.

[0157] The above-described embodiment can be modified as follows. [First Edge] The distance DT1 between the central axis 13AA and the first apex T1 may be longer than either the distance DE1 between the central axis 13AA and the first end E1 or the distance DE2 between the central axis 13AA and the second end E2. Even in this case, the first edge 13E1 has the first bottom B1, the first apex T1, and the second bottom B2, and thus the same effect as in (1) above can be obtained.

[0158] [Second Edge] The distance DT2 between the central axis 13AA and the second apex T2 may be longer than either the distance between the central axis 13AA and the third end E3 or the distance between the central axis 13AA and the fourth end E4. Even in this case, the second edge 13E2 has the third bottom B3, the second apex T2, and the fourth bottom B4, and thus the effect equivalent to that of (2) above can be obtained.

[0159] [Inner Spring] The first edge 13E1 may have the first bottom B1, the first peak T1, and the second bottom B2, while the second edge 13E2 may not have the third bottom B3, the second peak T2, and the fourth bottom B4. Even in this case, the effect equivalent to that of (1) above can be obtained.

[0160] The second edge 13E2 may have the third bottom B3, the second top T2, and the fourth bottom B4, while the first edge 13E1 may not have the first bottom B1, the first top T1, and the second bottom B2. Even in this case, the same effect as in (1) above can be obtained.

[0161] REFERENCE SIGNS LIST 10...Spring member 11...Outer frame portion 12...Inner frame portion 13...Spring portion 13A1...Outer spring 13A2...Inner spring 13E1...First edge portion 13E2...Second edge portion B1...First bottom portion B2...Second bottom portion B3...Third bottom portion B4...Fourth bottom portion E1...First end portion E2...Second end portion E3...Third end portion E4...Fourth end portion T1...First top portion T2...Second top portion

Claims

1. A spring comprising: a first surface; a second surface opposite to the first surface; and a plurality of springs arranged along a first direction in a cross section perpendicular to the first surface, the plurality of springs including a pair of outer springs and an inner spring sandwiched between the outer springs in the first direction, wherein the direction perpendicular to the first direction is a second direction, the inner spring having a first edge and a second edge opposing each other in the first direction, the first edge including a first end located on the first surface and a second end located on the second surface, and a first bottom, a first peak, and a second bottom located between the first end and the second end in the second direction, the first peak being located between the first bottom and the second bottom in the second direction, the distance between a central axis of the inner spring extending along the second direction and the first peak in the first direction being shorter than at least one of the distance between the central axis and the first end and the distance between the central axis and the second end, A spring member, wherein in the first direction, the distance between the central axis and the first top is longer than the distance between the central axis and the first bottom and the distance between the central axis and the second bottom.

2. The spring member according to claim 1, wherein the second edge portion includes a third end portion located on the first surface, a fourth end portion located on the second surface, and a third bottom portion, a second peak portion, and a fourth bottom portion located between the third end portion and the fourth end portion in the second direction; the second peak portion is located between the third bottom portion and the fourth bottom portion in the second direction; the distance between the central axis extending along the second direction and the second peak in the first direction is shorter than at least one of the distance between the central axis and the third end portion and the distance between the central axis and the fourth end portion; and the distance between the central axis and the second peak in the first direction is longer than the distance between the central axis and the third bottom portion and the distance between the central axis and the fourth bottom portion.

3. A spring member according to claim 2, wherein in the second direction, the distance between the first apex and the second apex is shorter than the distance between the first apex and the third bottom and the distance between the first apex and the fourth bottom.

4. A spring member according to claim 2, wherein in the second direction, the distance between the first apex and the second apex is shorter than the distance between the second apex and the first bottom and the distance between the second apex and the second bottom.

5. A spring member as described in claim 2 or 4, wherein the width of the inner spring along the first direction has a maximum value at the first peak, the second peak, or between the first peak and the second peak in the second direction.

6. The spring member according to claim 5, wherein in the second direction, the width of the inner spring has a first minimum value between the first end and the first peak and a second minimum value between the second end and the first peak, and the percentage of the first minimum value to the maximum value and the percentage of the second minimum value to the maximum value are 66% or more.

7. The spring element according to claim 5, wherein in the second direction, the width of the inner spring has a first minimum value between the first end and the first peak and a second minimum value between the second end and the first peak, and the percentage of the distance between the maximum value and the first minimum value with respect to the thickness of the inner spring in the second direction and the percentage of the distance between the maximum value and the second minimum value with respect to the thickness of the inner spring are 24% or less.

8. The spring element according to claim 5, wherein the width of the inner spring in the second direction has a first minimum value between the first end and the first apex and a second minimum value between the second end and the second apex, and the percentage of the distance between the first minimum value and the second minimum value with respect to the thickness of the inner spring in the second direction is 39% or more and 46% or less.

9. A spring member according to any one of claims 1 to 3, wherein the thickness of the inner spring is 150 μm or more.

10. A spring member according to any one of claims 1 to 3, wherein the pitch of the plurality of springs is 100 μm or more and 200 μm or less, and the maximum width of each spring along the first direction is 1 / 2 or less of the pitch.

11. The spring member according to any one of claims 1 to 3, wherein the spring member comprises a base material including any one selected from the group consisting of stainless steel alloy, beryllium copper, nickel-tin copper, phosphor bronze, Corson alloy, and titanium copper, the base material having a first surface and a second surface opposite to the first surface of the base material, and the spring member further comprises a copper layer on at least one of the first surface of the base material and the second surface of the base material.

12. A camera module comprising the spring member according to any one of claims 1 to 3.

13. An electronic device comprising the camera module according to claim 12.

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