Patent Application
20240392853
The present disclosure relates to a metal foil for a spring member, a spring member for an electronic device, a method for manufacturing a metal foil for a spring member, and a method for manufacturing a spring member for an electronic device.
A camera module included in an electronic device with a camera, such as a tablet terminal or a smartphone, includes a drive mechanism for enabling autofocus and zoom. There are two known types of drive mechanisms: a lens drive method and a sensor drive method. The drive mechanism of the lens drive method includes a leaf spring that enables the position of the lens in an optical axis direction to be changed. The drive mechanism of the sensor drive method includes a leaf spring that enables the position of the lens of the image sensor in the optical axis direction to be changed (refer to, for example, Japanese Laid-Open Patent Publication No. 2014-059345 and Japanese Laid-Open Patent Publication No. 2020-170170).
The leaf spring needs to satisfy specific requirements for spring load and deflection within a limited volume. To satisfy the requirements for spring load and deflection, the leaf spring must be made of a high-hardness metal.
The width and thickness of the leaf spring contribute significantly to the spring load and deflection. A metal foil, which is the raw material for the leaf spring, is thinned to a predetermined thickness through rolling. Since the metal foil is made of a high-hardness metal, it is more difficult to achieve a uniform thickness of the metal foil through rolling compared to when it is made of a low-hardness metal.
The leaf spring is formed by wet-etching a metal foil. Variations in the thickness of the metal foil cause variations in the amount of etching, which in turn causes variations in the width of the leaf spring in the thickness direction. Variations in the width of the leaf spring in the thickness direction cause variations in the spring load and deflection of the leaf spring. This necessitates minimizing the variations in the spring width in the thickness direction.
A metal foil for a spring member that solves the above-described problem is a metal foil used to manufacture a spring member. The metal foil for the spring member includes a first region on which the spring member is formed. The first region has a square shape with one side being 300 mm. A difference value between a maximum value and a minimum value of a first thickness at each of points on a straight line in a rolling direction in the first region is a first difference value. A difference value between a maximum value and a minimum value of a second thickness at each of points on a straight line in a width direction orthogonal to the rolling direction is a second difference value. An absolute value of a difference value obtained by subtracting the second difference value from the first difference value is less than or equal to 0.8 μm.
A spring member for an electronic device that solves the above-described problem is a spring member for an electronic device formed from a metal foil for a spring member. A difference value between a maximum value and a minimum value of a first thickness at each of points on a straight line in a rolling direction of the metal foil for the spring member is a first difference value. A difference value between a maximum value and a minimum value of a second thickness at each of points on a straight line in a width direction orthogonal to the rolling direction is a second difference value. An absolute value of a difference value obtained by subtracting the second difference value from the first difference value is less than or equal to 0.8 μm.
A method for manufacturing a metal foil for a spring member that solves the above-described problem is a method for manufacturing a metal foil used to manufacture a spring member. The method for manufacturing the metal foil for the spring member includes rolling a base material and preparing rolled materials obtained by rolling the base material and then selecting the metal foil for the spring member from the rolled materials. Each of the rolled materials include a first region on which the spring member is formed. The first region has a square shape with one side being 300 mm. A difference value between a maximum value and a minimum value of a first thickness at each of points on a straight line in a rolling direction in the first region is a first difference value. A difference value between a maximum value and a minimum value of a second thickness at each of points on a straight line in a width direction orthogonal to the rolling direction is a second difference value. The selecting the metal foil for the spring member selects, from the rolled materials, as the metal foil for the spring member, the rolled material in which an absolute value of a difference value obtained by subtracting the second difference value from the first difference value is less than or equal to 0.8 μm.
A method for manufacturing a spring member for an electronic device that solves the above-described problem is a method for manufacturing a spring member for an electronic device formed from a metal foil for a spring member. The manufacturing method includes forming a resist mask on a front surface and a back surface of the metal foil for the spring member and wet-etching the metal foil for the spring member using the resist mask. A difference value between a maximum value and a minimum value of a first thickness at each of points on a straight line in a rolling direction of the metal foil for the spring member is a first difference value. A difference value between a maximum value and a minimum value of a second thickness at each of points on a straight line in a width direction orthogonal to the rolling direction is a second difference value. An absolute value of a difference value obtained by subtracting the second difference value from the first difference value is less than or equal to 0.8 μm.
A metal foil for a spring member, a spring member for an electronic device, a method for manufacturing a metal foil for a spring member, and a method for manufacturing a spring member for an electronic device according to an embodiment will now be described with reference to
The metal foil for the spring member will now be described with reference to
In a metal foil 10 for a spring member (hereinafter also referred to as a metal foil 10) shown in
In the first region 10R1, the difference value between the maximum value and the minimum value of the thickness in the rolling direction DR is a first difference value. That is, the thickness at each point on one straight line in 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 the first difference value. In the first region 10R1, the difference value between the maximum value and the minimum value of the thickness in the width direction DW is a second difference value. That is, thickness T at each point on one straight line in the width direction DW is a 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 satisfies the following condition 1.
The absolute value of the difference value obtained by subtracting the second difference value from the first difference value is a first absolute value.
Since the first absolute value is less than or equal to 0.8 μm, variations in the thickness of the metal foil 10 are limited. Thus, variations in the spring width in the thickness direction are limited in the spring member that has been formed by wet-etching the metal foil 10.
The metal foil 10 has a front surface 10F and a back surface 10B that is opposite to the front surface 10F. 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 specified as follows. A first measurement region R1R, having a band shape extending in the rolling direction DR, is set within the first region 10R1. The dimension of the first measurement region R1R in the width direction DW is, for example, 20 mm. Of the thicknesses of the metal foil 10 measured at multiple points in the first measurement region R1R, the largest value is the maximum value, and the smallest value is the minimum value.
The maximum value and the minimum value of the thickness in the width direction DW are specified as follows. A second measurement region R1W, having a band shape extending in the width direction DW, is set within the first region 10R1. The dimension of the second measurement region R1W in the rolling direction DR is, for example, 20 mm. Of the thicknesses of the metal foil 10 measured at multiple points in the second measurement region R1W, the largest value is the maximum value, and the smallest value is the minimum value.
The variations in thickness of the metal foil 10 in the rolling direction DR decrease as rolling is repeatedly applied to the material used to manufacture the metal foil 10. Thus, to limit variations in the rolling direction DR, increasing the number of rolling passes during the manufacturing of the metal foil 10 is preferred. However, the metal foil 10 for the spring member needs to have a thickness that is greater than or equal to a predetermined thickness to achieve the spring load or deflection required for the spring member. This hinders performing a sufficient number of rolling passes to completely eliminate the variations in thickness of the metal foil 10 for the spring member in the rolling direction DR during the manufacturing of the metal foil 10. In contrast, the variations in thickness of the metal foil 10 in the width direction DW are controlled by the surface condition of the roller used in the rolling. Accordingly, the variations are limited regardless of the number of rolling passes. Thus, the second difference value of the metal foil 10 is less than or equal to the first difference value.
When wet-etching is performed on the metal foil 10 to form through-holes that extend through the metal foil 10 in the thickness direction of the metal foil 10, the thinner the part of the metal foil 10, the shorter the time required to form the through-holes. The through-holes formed in the metal foil 10 create a flow of etchant between the front surface 10F and the back surface 10B of the metal foil 10. However, these through-holes do not significantly contribute to the isotropic etching of the metal foil 10 in the direction perpendicular to the through-holes. In contrast, the thicker the part of the metal foil 10, the longer the time required to form the through-holes. Accordingly, the thicker parts of the metal foil 10 significantly contribute to the progress of isotropic etching of the metal foil 10.
Thus, in the thickness of the metal foil 10, the first difference value can be used as an index of the ease of isotropic etching in the rolling direction DR. Further, in the thickness of the metal foil 10, the second difference value can be used as an index of the ease of isotropic etching in the width direction DW. Furthermore, the first absolute value can be used as an index of the ease of isotropic etching in the rolling direction DR relative to the width direction DW, in which isotropic etching is less likely to occur.
In this regard, when the metal foil 10 meets the aforementioned condition 1, it prevents the ease of isotropic etching in the rolling direction DR from being significantly greater than the ease of isotropic etching in the width direction DW. Thus, the desired shape is more likely to be obtained in the spring member formed by etching the metal foil 10.
In the first region 10R1, the maximum value of thickness T in the rolling direction DR is a first maximum value. In the first region 10R1, the maximum value of thickness T in the width direction DW is a second maximum value. The metal foil 10 preferably satisfies at least one of the following conditions 2 and 3. That is, the metal foil 10 may satisfy only one of the conditions 2 and 3, or may satisfy both of the conditions 2 and 3.
The absolute value of the difference value obtained by subtracting the second maximum value from the first maximum value is a second absolute value.
As described above, even if a through-hole is formed in relatively thin portions of the metal foil 10, the through-hole contributes to the formation of the flow of etchant in the thickness direction of the metal foil 10 but is less conducive to the progress of isotropic etching. By contrast, the thicker portions of the metal foil 10 require more time for wet-etching than other portions, thereby contributing to isotropic etching progress in the metal foil 10.
When the metal foil 10 satisfies condition 2, variations are limited in the metal foil 10 in the degree of isotropic etching in the rolling direction DR and the width direction DW. As a result, variations are limited in the spring width in the thickness direction of the spring member.
When the metal foil 10 satisfies condition 3, variations are limited in the thickness of the entire metal foil 10.
The maximum value of thickness T of the metal foil 10 is the largest value of all measurement values of thickness T, including the measurement value of thickness T in the rolling direction DR and the measurement value of thickness T in the width direction DW. The minimum value of thickness T of the metal foil 10 is the smallest value of all measurement values of thickness T, including the measurement value of thickness T in the rolling direction DR and the measurement value of thickness T in the width direction DW.
As described above, the metal foil 10 is a rolled material made of metal having a hardness high enough to achieve a spring load or deflection required for the spring member manufactured using the metal foil 10. The metal foil 10 may be made of, for example, a stainless alloy or a copper alloy. The stainless alloy may be, for example, stainless alloy specified in JIS G 4313:2011, “Stainless steel strip for springs.” The copper alloy may be, for example, copper alloy specified in JIS H 3130:2018, “Copper beryllium alloy, copper titanium alloy, phosphor bronze, copper-nickel-tin alloy and nickel silver sheets, plates and strips for springs.”
The metal foil 10 preferably includes any one selected from the group consisting of stainless alloy, beryllium copper, nickel-tin-copper, phosphor bronze, Corson alloy, and titanium copper. As a result, since the metal foil 10 can have a relatively high hardness, the durability of the spring member formed from the metal foil 10 is enhanced.
The spring member will now be described with reference to
As shown in
In the drive mechanism of the lens drive method, two spring members 20 are arranged on opposite sides of the lens in the optical axis direction of the lens. A change in the position of the inner frame 22 connected to each outer frame 21, in relation to the outer frame 21, in the optical axis direction changes the position of the lens in the optical axis direction. This allows the lens drive mechanism to correct for camera shake.
In the drive mechanism of the sensor drive method, two spring members 20 are arranged on opposite sides of an imaging sensor in the optical axis direction of the lens. A change in the position of the inner frame 22 connected to each outer frame 21, in relation to the outer frame 21, in the optical axis direction changes the position of the imaging sensor in the optical axis direction. This allows the sensor drive mechanism to correct for camera shake.
In the spring member 20, in a plan view facing the plane in which the spring member 20 expands, the length in a direction orthogonal to the direction in which each side of the outer frame 21 extends is the width of the spring member 20 in the outer frame 21. Further, in a plan view facing the plane in which the spring member 20 expands, the length of the inner frame 22 in the radial direction of the inner frame 22 is the width of the spring member 20 in the inner frame 22. In addition, in a plan view facing a plane in which the spring member 20 expands, the line width of the folding line in the spring portion 23 in the plan view is the width of the spring portion 23; that is, a spring width SW.
The electronic device on which the camera module with the spring member 20 is mounted may be, for example, a mobile phone terminal, a smartphone, a tablet terminal, or a notebook personal computer.
The method for manufacturing the metal foil 10 will now be described with reference to
The method for manufacturing the metal foil 10 includes rolling a base material, preparing rolled materials that have been obtained by rolling the base material, and then selecting the metal foil 10 from the rolled materials. In the selection of the metal foil 10, a rolled material satisfying the above-described condition 1 is selected from the rolled materials as the metal foil 10. The method for manufacturing the metal foil 10 may further include at least one of the above-described conditions 2 and 3 as a condition for selecting the metal foil 10 from the rolled materials.
The method for manufacturing the metal foil 10 will now be described in more detail with reference to the drawings.
As shown in
When the base material BM1 reaches the section between the two rollers RL1, RL2, the base material BM1 is rolled by the two rollers RL1, RL2. Thus, the thickness of the base material BM1 is reduced and the base material BM1 is extended in the conveying direction. As a result, the rolled material BM2 is obtained. The rolled material BM2 is wound around core C. The rolled material BM2 may be treated while it is extended in a strip shape without being wound around core C. The thickness of the rolled material BM2 is, for example, less than or equal to 200 μm, and preferably between 50 μm and 200 μm, inclusive.
As shown in
The material used to form the base material BM1 may include any one selected from the group consisting of stainless alloy, beryllium copper, nickel-tin-copper, phosphor bronze, Corson alloy, and titanium copper. These metals have a relatively high hardness. In other words, they are less ductile compared to metals with lower hardness (i.e., softer metals) Thus, variations in the degree of rolling are likely to occur in the base material BM1. In addition, the rolling degree is likely to vary between multiple base materials BM1. Thus, the effectiveness of including the above condition 1 in the condition for selecting the metal foil 10 formed by the rolling of the base material BM1 is relatively high.
As shown in
For the first region of each rolled material BM3, the above-described first and second maximum values, and the maximum and minimum values of thickness T of the rolled material BM3 may be calculated. At least one of the above conditions 2 and 3 may be added to the condition for selecting the metal foil 10 from the rolled material BM3. That is, only one of the conditions 2 and 3 or both of the conditions 2 and 3 may be added to the condition for selecting the metal foil 10 from the rolled material BM3 may be added to the condition. Additionally, the measuring device ME can be either a contact measuring device or a non-contact measuring device.
The contact measuring device may be, for example, a length gauge. The non-contact measuring device may be, for example, a measuring device including an emitter that emits X-rays and a detector that detects fluorescent X-rays. When this measuring device is used, first, X-rays are emitted to the metal foil 10 using the emitter, and then fluorescent X-rays released from the metal foil 10 are detected using the detector. Since the intensity of the fluorescent X-rays detected by the detector depends on the thickness of the metal foil 10, the thickness of the metal foil 10 can be deduced from the intensity of the fluorescent X-rays.
The first absolute value, the second absolute value, and the difference between the maximum value and the minimum value of thickness T of the metal foil 10 may be changed by changing at least one of the following pentameters. The above values can be changed by changing at least one of the rotation speeds of the rollers RL1, RL2, the pressing force between the rollers RL1, RL2, the temperatures of the rollers RL1, RL2, and the number of the rollers RL1, RL2. That is, only one of the rotation speeds of the rollers RL1, RL2, the pressing force between the rollers RL1, RL2, the temperatures of the rollers RL1, RL2, and the number of the rollers RL1, RL2 may be changed. Alternatively, two or more of the rotation speeds of the rollers RL1, RL2, the pressing force between the rollers RL1, RL2, the temperatures of the rollers RL1, RL2, and the number of the rollers RL1, RL2 may be changed.
The method for manufacturing the spring member 20 will now be described with reference to
As shown in
Next, as shown in
As shown in
As shown in
Since the metal foil 10 satisfies condition 1, the spring member 20 having the desired shape in the thickness direction of the metal foil 10 is likely to be obtained. Additionally, since the metal foil 10 satisfies condition 1, it is possible to obtain the spring member 20 in which the variations in the spring width in the thickness direction of the spring member 20 are limited within a predetermined range without changing the condition of wet-etching based on the variations in the thickness of the metal foil 10. This eliminates the need to modify the condition of wet-etching based on the variations in thickness in the process of manufacturing the spring member 20. Consequently, errors that result from the combination of thickness variations and the wet-etching condition are eliminated.
As shown in
Examples and Comparative Examples will be described with reference to
First, a base material made of titanium copper was subjected to a rolling step to form a rolled material. Next, the rolled material was subjected to an annealing step. Thus, a metal foil of Example 1 having a design value of thickness of 120 μm was obtained.
Metal foils of Examples 2 to 8 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1, except that at least one of the rotation speeds of the rollers, the pressing force between the rollers, the temperatures of the rollers, and the number of rollers was changed during rolling of the base material in Example 1.
The method for measuring the thickness of the metal foil 10 will now be described with reference to
As shown in
Further, the first measurement region R1R, having a band shape that extends in the rolling direction DR, and the second measurement region R1W, having a band shape that extends in the width direction DW, were set within the measurement region 30A. Width W1 of the first measurement region R1R in the width direction DW was set to 20 mm. Width W2 of the second measurement region R1W in the rolling direction DR was set to 20 mm.
The thickness of the metal foil was measured in all of the fourteen equally divided sections of the first measurement region R1R in the rolling direction DR. Further, the thickness of the measurement metal foil 30 was measured in all of the fourteen equally divided sections of the second measurement region R1W in the width direction DW.
In each section, the thickness was measured at the point where the diagonal lines connecting the two opposing corners intersected. The thickness of each measurement metal foil was measured at the fourteen points in the rolling direction DR and at the fourteen points in the width direction DW. In the region where the first measurement region R1R and the second measurement region R1W intersected each other, the measurement point in the rolling direction DR was the same as the measurement point in the width direction DW. Thus, the thickness of each measurement metal foil was measured at twenty-seven points in total. Then, the measured value was rounded off to the second decimal place, thereby obtaining a measurement of the thickness in each region. From the measurement values in the rolling direction DR of these measurement values, the average value, maximum value, minimum value, and first difference value of a rolling direction thickness (the thickness in the rolling direction DR) were calculated. From the measurement values in the width direction DW, the average value, maximum value, minimum value, and second difference value of a width direction thickness (the thickness in the width direction DW) were calculated.
The thickness of the measurement metal foil 30 was measured using a contact thickness gauge (manufactured by Nikon Corporation, MH-15M). To measure the thickness, first, a probe was brought into contact with the base plate, and then the power of the thickness gauge counter attached to the measuring device was turned on, thereby performing zero calibration. Afterward, the measurement metal foil was placed between the probe and the base plate, and then the probe was lowered to measure the thickness at each point on the measurement metal foil.
A resist mask with multiple openings that conform to the shape of the spring member 20 was formed on the front and back surfaces of each measurement metal foil 30. The measurement metal foil 30 was wet-etched from the front and back surfaces using the two resist masks. In the measurement region 30A, unit areas corresponding to a single spring member 20 and having a square shape of 20 mm on each side were arranged in a grid pattern to cover the region in the rolling direction DR and the width direction DW. Thus, unit patterns corresponding to the shape of a single spring member 20 were arranged in a grid pattern on each resist mask, covering the rolling direction DR and the width direction DW.
The unit patterns included the section of the spring member 20 forming the spring portion 23, which had a zigzag shape. In this section, the opening width of the resist pattern corresponding to the gap between line segments of the spring portion 23 that were parallel to and adjacent to each other was set to 100 μm, and the pitch between the adjacent line segments was set to 200 μm. The pitch of the adjacent line segments referred to the distance between the center lines set for the line segments, which were parallel to and adjacent to each other, in the design of etching pattern.
On each resist mask, multiple unit patterns were formed so that, in a plan view facing the front surface of the measurement metal foil 30, the entire unit pattern of the resist mask on the front surface of the measurement metal foil 30 was overlapped with the entire unit pattern on the resist mask on the back surface of the measurement metal foil 30.
Using such a resist mask, etching patterns corresponding to the shape of the spring member 20 were formed in the measurement metal foil 30. In the etching patterns, the design value of the spring width of the spring portion 23 in a plan view was set to 30 μm.
The spring portion 23 of the spring member 20 in each etched measurement metal foil 30 was embedded using synthetic resin. Then, the embedded spring portion 23 was cut using a microtome to expose 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 extended.
In the cross-section of the spring portion 23, the spring width was measured at the following position. In the spring portion 23, the spring width on the front surface of the measurement metal foil 30 and the spring width on the back surface of the measurement metal foil 30 were measured. Further, of the plane that divided the spring portion 23 into four equal parts in the thickness direction, the spring widths on three planes located between the front and back surfaces of the measurement metal foil 30 were measured. That is, when the depth of the measurement metal foil 30 on the front surface was set to 0 μm, the spring width at a depth of 0 μm, the spring width at a depth of about 30 μm, the spring width at a depth of about 60 μm, the spring width at a depth of about 90 μm, and the spring width at a depth of about 120 μm were measured in the etching patterns. To measure the spring width of the spring portion 23, a digital microscope (VHX-7000, manufactured by Keyence Corporation) was used, and the magnification of the objective lens in the digital microscope was set to 200 times.
For each unit pattern included in the measurement metal foil 30, the spring widths of all the springs included in the spring portion 23 were measured at the above-described five positions in the thickness direction. Then, the maximum value and the minimum value were specified for each spring, the difference value obtained by subtracting the maximum value from the minimum value was calculated, and the average value of the spring widths was calculated. Next, the average value of the maximum values specified for all the springs was calculated, and this average value was set as the maximum value of the spring width in the measurement metal foil 30. Further, the average value of the minimum values specified for all the springs was calculated, and this average value was set as the minimum value of the spring width in the measurement metal foil 30. Furthermore, the average value of the difference values calculated for all the springs was calculated, and this average value was set as the difference value of the measurement metal foil 30. In addition, the average value of the average values calculated for all the springs was calculated, and this average value was set as the average value of the measurement metal foil 30.
Further, the first specified value, the standard deviation of the spring width, the second specified value, and the percentage of 3σ relative to the average value of the spring width were calculated for the etching pattern obtained from the measurement metal foil 30 of each of Examples and Comparative Examples. To calculate the percentage of 3σ relative to the average value of the spring width, the average value set for each measurement metal foil 30 was used. The first specified value was a percentage of the difference value of the spring width relative to the design value of the spring width. To calculate the first specified value, the difference value set for each measurement metal foil 30 was used. The second specified value was a percentage of the standard deviation of the spring width relative to the design value of the spring width.
To calculate the standard deviation of the spring width, first, the standard deviation of the spring width was calculated from the thicknesses at five points measured for each spring. Next, the average value of the standard deviations calculated for all the springs was calculated, and this average value was set as the standard deviation of the spring width of the measurement metal foil 30. To calculate the second specified value, the standard deviation set for each measurement metal foil 30 was used.
The evaluation results of the thickness of the measurement metal foil 30 and the spring width of the etching pattern will now be described with reference to
As shown in
It was confirmed that the second difference value, which was the value obtained by subtracting the minimum value from the maximum value of the width direction thickness (the thickness in the width direction DW), was 0.6 μm in Example 1, 1.3 μm in Example 2, 1.0 μm in Example 3, and 0.4 μm in Example 4. Further, it was confirmed that the second difference value was 0.8 μm in Example 5, 1.0 μm in Example 6, 1.5 μm in Example 7, and 1.4 μm in Example 8. It was confirmed that the second difference value was 0.7 μm in Comparative Example 1, 0.6 μm in Comparative Example 2, and 1.0 μm in Comparative Example 3.
Thus, it was confirmed that the first absolute value was 0.3 μm in Example 1, 0.5 μm in Example 2, 0.3 μm in Example 3, and 0.8 μm in Example 4. Further, it was confirmed that the first absolute value was 0.2 μm in Example 5, 0.0 μm in Example 6, 0.2 μm in Example 7, and 0.4 μm in Example 8. Furthermore, it was confirmed that the first 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.
Thus, it was confirmed that the first absolute value was less than or equal to 0.8 μm in the measurement metal foil 30 of Examples 1 to 8 whereas the first absolute value was larger than 0.8 μm in the measurement metal foils 30 of Comparative Examples 1 to 3. Further, it was confirmed that the first difference value is greater than or equal to the second difference value in the measurement metal foils 30 of Examples 1 to 8 and the measurement metal foils 30 of Comparative Examples 1 to 3.
In addition, it was confirmed that the second absolute value was 0.0 μm in Example 1, 0.8 μm in Example 2, 0.4 μm in Example 3, and 0.1 μm in Example 4. It was confirmed that the second absolute value was 0.0 μm in Example 5, 0.0 μm in Example 6, 0.4 μm in Example 7, and 0.6 μm in Example 8. Further, it was confirmed that the second 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. Thus, it was confirmed that the second absolute values of the measurement metal foils 30 of Examples 1 to 8 were less than or equal to 0.8 μm whereas the second absolute values of the measurement metal foils 30 of Comparative Examples 1 to 3 were larger than 0.8 μm.
It was confirmed that the difference value obtained by subtracting the minimum value from the maximum value of the thickness of the measurement metal foil 30 was 0.9 μm in Example 1, 2.6 μm in Example 2, 1.7 μm in Example 3, and 1.3 μm in Example 4. Further, it was confirmed that the difference value obtained by subtracting the minimum value from the maximum value of the thickness of the measurement metal foil 30 was 1.0 μm in Example 5, 1.0 μm in Example 6, 2.1 μm in Example 7, and 2.4 μm in Example 8. Furthermore, it was confirmed that the difference value obtained by subtracting the minimum value from the maximum value of the thickness of the measurement metal foil 30 was 2.3 μm in Comparative Example 1, 1.8 μm in Comparative Example 2, and 1.9 μm in Comparative Example 3.
It was confirmed that the difference value obtained by subtracting the minimum value from the maximum value of the spring width of the etching pattern was 7.0 μm in Example 1, 7.5 μm in Example 2, 8.2 μm in Example 3, and 8.1 μm in Example 4. Further, it was confirmed that the difference value obtained by subtracting the minimum value from the maximum value of the spring width of the etching pattern was 8.4 μm in Example 5, 8.4 μm in Example 6, 8.4 μm in Example 7, and 9.7 μm in Example 8. Furthermore, it was confirmed that the difference value obtained by subtracting the minimum value from the maximum value of the spring width of the etching pattern was 12.5 μm in Comparative Example 1, 13.7 μm in Comparative Example 2, and 14.3 μm in Comparative Example 3.
In addition, it was confirmed that the first specified value was 23.1% in Example 1, 24.9% in Example 2, 27.4% in Example 3, and 27.2% in Example 4. Further, it was confirmed that the first specified value was 27.9% in Example 5, 28.0% in Example 6, 28.1% in Example 7, and 32.3% in Example 8. Furthermore, it was confirmed that the first specified 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 1.4 μm in Example 1, 1.4 μm in Example 2, 1.9 μm in Example 3, and 1.9 μm in Example 4. It was confirmed that the standard deviation of the spring width was 2.0 μm in Example 5, 1.7 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 specified value was 4.7% in Example 1, 4.7% in Example 2, 6.3% in Example 3, and 6.4% in Example 4. It was confirmed that the second specified value was 6.6% in Example 5, 5.7% in Example 6, 6.6% in Example 7, and 7.1% in Example 8. It was confirmed that the second specified 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 relative to the average value of the spring width was 13.0% in Example 1, 13.0% in Example 2, 18.3% in Example 3, and 17.1% in Example 4. It was confirmed that the percentage of 3σ relative to the average value of the spring width was 17.8% in Example 5, 16.0% in Example 6, 18.3% in Example 7, and 18.8% in Example 8. It was confirmed that the percentage of 3σ relative to the average value of the spring width was 24.8% in Comparative Example 1, 26.4% in Comparative Example 2, and 22.0% in Comparative Example 3.
Thus, it was confirmed that the first specified values of the spring widths of the metal foils for the spring members of Examples 1 to 8 were smaller than those of the metal foils for the spring members of Comparative Examples 1 to 3. Accordingly, the metal foils for the spring members of Examples 1 to 8 have smaller variations in the spring width in the thickness direction than the metal foils for the spring members of Comparative Examples 1 to 3.
Further, it was confirmed that the standard deviations of the spring widths of the metal foils for the spring members of Examples 1 to 8 were smaller than those of the metal foils for the spring members of Comparative Examples 1 to 3. Accordingly, the metal foils for the spring members of Examples 1 to 8 have smaller variations in the spring width in the thickness direction than the metal foils for the spring members of Comparative Examples 1 to 3.
Furthermore, it was confirmed that the second specified values of the spring widths of the metal foils for the spring members of Examples 1 to 8 were smaller than those of the metal foils for the spring members of Comparative Examples 1 to 3. Accordingly, the metal foils for the spring members of Examples 1 to 8 have smaller variations in the spring width in the thickness direction than the metal foils for the spring members of Comparative Examples 1 to 3.
In addition, it was confirmed that the percentages of 3σ relative to the average values of the spring widths of the metal foils for the spring members of Examples 1 to 8 were smaller than those of the metal foils for the spring members of Comparative Examples 1 to 3. Accordingly, the metal foils for the spring members of Examples 1 to 8 have smaller variations in the spring width in the thickness direction than the metal foils for the spring members of Comparative Examples 1 to 3.
As shown in
As shown in
As described above, the metal foil for the spring member, the spring member for the electronic device, the method for manufacturing the metal foil for the spring member, and the method for manufacturing the spring member for the electronic device according to the embodiment provide the following advantages.
The technical concept obtained from the above embodiment and the modification will now be described.
A metal foil for a spring member used to manufacture a spring member, the metal foil including a first region on which the spring member is formed, the first region having a square shape with one side being 300 mm, where
Wet-etching is performed so that a through-hole extending through a metal foil for a spring member is formed in the metal foil for the spring member in the thickness direction of the metal foil for the spring member. In this case, the thinner the parts of the metal foil for the spring member, the more easily a hole extends through the metal foil. By contrast, the thicker the part of the metal foil for the spring member, the less easily a hole extends through the metal foil. Even if a through-hole is formed in relatively thin parts of the metal foil for the spring member, the through-hole helps form the flow of etchant in the thickness direction of the metal foil for the spring member, but is less conducive to the progress of isotropic etching in a direction perpendicular to the extending direction. In contrast, the thicker sections of the metal foil for the spring member require more time for wet etching compared to other sections. This contributes to isotropic etching progression in the metal foil for the spring member.
In the metal foil for the spring member, the absolute value of the difference value obtained by subtracting the second maximum value from the first maximum value is less than or equal to 0.8 μm. Thus, variations are limited in the metal foil for the spring member in the degree of isotropic etching in the rolling direction and the width direction. As a result, variations in the spring width of the spring member in the thickness direction are limited.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-019988 | Feb 2022 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2022/035025 | Sep 2022 | WO |
| Child | 18795968 | US |
