Metal body for etching and method for visually inspecting metal body for etching

Abstract

To provide a metal body for etching that excels in flatness, and a method for visually inspecting the metal body for etching with which it is possible to easily analyze the flatness of the metal body for etching.SOLUTION: Provided is a metal body for etching, of which the difference between the luminance of a flat part and the luminance of an uneven part on the surface of the metal body for etching is less than 60, with the luminance measured by a visual inspection method below. Visual inspection method: irradiating the surface of the metal body for etching with white illumination light; adjusting the illuminance of while illumination light so that the luminance of the flat part on the surface becomes 100; irradiating the surface of the metal body for etching with white illumination light and acquiring, by an inspection unit, image data on the surface of the metal body for etching while the reflected light of white illumination light is obtained; acquiring, from the image data, a profile of luminance on the surface of the metal body for etching over the flat part and the uneven part on the surface of the metal body for etching; and extracting the peak of luminance of the flat part and the peak of luminance of the uneven part and calculating the difference between the luminance of the flat part and the luminance of the uneven part (luminance of flat part - luminance of uneven part).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a metal body for etching and a method for inspecting the appearance of the metal body for etching.

Background Art

[0002] In the manufacturing process of metal foil or in a production line using metal foil, it is impossible to make the surface of the metal foil free from unevenness. Particularly in the resist formation process where a photolithography process is performed, whether using a dry film or a liquid, the resist may have difficulty following the unevenness on the surface of the metal foil. When the resist does not follow the unevenness on the surface of the metal foil, if the metal foil is etched, defects (places where the intended etching is not performed) will occur on the metal foil. However, the unevenness on the surface of the metal foil may not be a problem depending on the degree. Although a threshold value can be set by precisely measuring the height and depth of the unevenness, it is not practical to precisely measure the height and depth of the unevenness with a manufacturing apparatus because it would increase the time required for manufacturing. Also, when inspecting the metal foil, since destructive inspection is common, the metal foil to be measured cannot maintain its shape as a product.

[0003] As a method for evaluating the unevenness (deformation) generated on the surface of a conventional base material for metal etching such as metal foil, for example, by a measuring device in which the wavelength difference between the peak wavelength of the first illumination light and the peak wavelength of the second illumination light is 5 nm or more and 90 nm or less, at least the first illumination light and the second illumination light are irradiated on the metal body, the reflected light of the illumination light from the metal body is measured separately, and based on the measurement result of the luminance value of the reflected light by the measuring device, an arithmetic processing device that calculates information for inspecting the shape of the metal body uses the difference between the luminance value of the reflected light of the first illumination light and the luminance value of the reflected light of the second illumination light to calculate the inclination of the surface of the metal body as information (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the method described in Patent Document 1 is an inspection method using at least two illumination lights, there is a problem that the analysis becomes complicated.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a metal body for etching having excellent flatness and an appearance inspection method for a metal body for etching capable of easily analyzing the flatness of the metal body for etching.

Means for Solving the Problems

[0007] That is, the present invention has the following aspects. [1] A metal body for etching used for forming an etching pattern, wherein the difference between the luminance of the flat portion and the luminance of the uneven portion on the surface of the metal body for etching is less than 60, and the luminance is measured by the following appearance inspection method for a metal body for etching, a metal body for etching. (Appearance Inspection Method for Metal Body for Etching) Irradiate the surface of the metal body for etching with white illumination light, adjust the illuminance of the white illumination light so that the luminance of the flat portion on the surface of the metal body for etching becomes 100, irradiate the surface of the metal body for etching with white illumination light, and in a state where the reflected light of the white illumination light reflected from the surface of the metal body for etching is obtained, acquire image data of the surface of the metal body for etching with an inspection unit, and from the image data, across the flat portion and the uneven portion on the surface of the metal body for etching, acquire a luminance profile of the surface of the metal body for etching, extract the peak of the luminance of the flat portion and the peak of the luminance of the uneven portion, and calculate the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion). [2] The etching metal body according to [1], wherein the thickness of the etching metal body is 5 μm or more and 50 μm or less. [3] The etching metal body according to [1], wherein the etching metal body is an iron-based metal. [4] The etching metal body according to [3], wherein the iron-based metal is a stainless alloy, an iron-nickel alloy, or an iron-nickel-cobalt alloy. [5] An appearance inspection method for the surface of an etching metal body used for forming an etching pattern, comprising: irradiating white illumination light onto the surface of the etching metal body, and adjusting the illuminance of the white illumination light so that the luminance of the flat portion on the surface of the etching metal body becomes 100; irradiating white illumination light onto the surface of the etching metal body, and obtaining image data of the surface of the etching metal body by an inspection unit in a state where reflected light of the white illumination light reflected from the surface of the etching metal body is obtained; obtaining a luminance profile of the surface of the etching metal body over the flat portion and the uneven portion on the surface of the etching metal body from the image data, extracting the peak of the luminance of the flat portion and the peak of the luminance of the uneven portion, and calculating the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion). An appearance inspection method for an etching metal body. [6] The appearance inspection method for an etching metal body according to [5], wherein the etching metal body is arranged in three directions of -45°, 0°, and +45° clockwise with respect to the inspection unit to obtain image data of the surface of the etching metal body. [7] The appearance inspection method for an etching metal body according to [5], wherein the inspection unit is arranged in three directions of -45°, 0°, and +45° clockwise with respect to the etching metal body to obtain image data of the surface of the etching metal body. [8] The angle A formed between the vertical plane of the metal body for etching and the white illumination light incident on the surface of the metal body for etching, and the angle B formed between the vertical plane of the metal body for etching and the reflected light received from the surface of the metal body for etching are less than 90°, the method for inspecting the appearance of the metal body for etching according to [5]. [9] The angle A and the angle B are different, the method for inspecting the appearance of the metal body for etching according to [8].

[10] The difference between the angle A and the angle B is 1° or more and 10° or less, the method for inspecting the appearance of the metal body for etching according to [8].

Effect of the Invention

[0008] According to the present invention, it is possible to provide a metal body for etching with excellent flatness and a method for inspecting the appearance of the metal body for etching that can easily analyze the flatness of the metal body for etching.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] [Metal Body for Etching] A metal body for etching according to an embodiment of the present invention will be described.

[0011] The metal body for etching according to this embodiment is a metal body for etching used for forming an etching pattern, and the difference between the luminance of the flat portion and the luminance of the uneven portion on the surface of the metal body for etching is less than 60, and the luminance is measured by the following method for inspecting the appearance of the metal body for etching. Metal body for etching. (Method for inspecting the appearance of the metal body for etching) Irradiate the surface of the metal body for etching with white illumination light, adjust the illuminance of the white illumination light so that the luminance of the flat portion on the surface of the metal body for etching becomes 100, and irradiate the surface of the metal body for etching with white illumination light. While obtaining the reflected light of the white illumination light reflected on the surface of the metal body for etching, the inspection unit acquires the image data of the surface of the metal body for etching, and from the image data, the flat portion on the surface of the metal body for etching and the uneven portion are obtained. A luminance profile of the surface of the metal body for etching is obtained, the peak luminance of the flat portion and the peak luminance of the uneven portion are extracted, and the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion) is calculated.

[0012] The metal body for etching according to this embodiment is used, for example, as a metal body for a metal mask for manufacturing an internal electrode of an MLCC (multilayer ceramic chip capacitor). The metal mask for manufacturing the internal electrodes of MLCCs requires flatness (less unevenness on the surface).

[0013] In the metal body for etching according to this embodiment, the difference between the luminance of the flat portion and the luminance of the uneven portion on the surface of the metal body for etching measured by the above-described method for inspecting the appearance of the metal body for etching is less than 60, preferably less than 40, and more preferably less than 20. If the difference between the luminance of the flat portion and the luminance of the uneven portion exceeds 60, significant uneven portions exist on the surface of the metal body for etching, and the flatness of the surface of the metal body for etching is not sufficient. The uneven portion is a general term for recesses (depressions) and protrusions (bulges) present on the surface of the metal body for etching. The flat portion is a normal portion where no recesses (depressions) and protrusions (bulges) exist on the surface of the metal body.

[0014] The method for inspecting the appearance of the metal body for etching will be described later.

[0015] The thickness of the metal body for etching is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 30 μm or less, and even more preferably 15 μm or more and 25 μm or less. When the thickness of the metal body for etching approaches the lower limit value, it is easy to obtain an etched product with a high-definition etching pattern by only one-sided etching. When the thickness of the metal body for etching approaches the upper limit value, an etched product with high rigidity can be obtained by etching from both the front and back.

[0016] The metal body for etching is preferably an iron-based metal. More specifically, it is preferably a stainless alloy, an iron-nickel-based alloy, or an iron-nickel-cobalt-based alloy. The stainless alloy, iron-nickel-based alloy, or iron-nickel-cobalt-based alloy is not particularly limited. For example, in the case of a stainless alloy, SUS304, SUS430, in the case of an iron-nickel-based alloy, an invar material, and in the case of an iron-nickel-cobalt-based alloy, a super invar material, etc. can be mentioned. In particular, SUS430, invar material, and super invar material have ferromagnetism. SUS304 has no magnetism.

[0017] The metal body for etching of the present embodiment has excellent flatness because the difference between the luminance of the flat part and the luminance of the uneven part on the surface of the metal body for etching, measured by the method for inspecting the appearance of the metal body for etching, is less than 60. Therefore, when the metal body for etching of the present embodiment is used in, for example, the resist formation process for performing a photolithography process, since the resist follows its surface, it is possible to suppress the occurrence of defects (places where the intended etching is not performed) when passing through the etching process.

[0018] [Method for Inspecting the Appearance of the Metal Body for Etching] An appearance inspection method for an etching metal body according to an embodiment of the present invention is an appearance inspection method for the surface of an etching metal body used for forming an etching pattern. The method includes a step of irradiating the surface of the etching metal body with white illumination light and adjusting the illuminance of the white illumination light so that the luminance of the flat portion on the surface of the etching metal body becomes 100; a step of irradiating the surface of the etching metal body with white illumination light, obtaining the reflected light of the white illumination light reflected from the surface of the etching metal body, and acquiring, by an inspection unit, image data of the surface of the etching metal body; and a step of obtaining a luminance profile of the surface of the etching metal body across the flat portion and the uneven portion on the surface of the etching metal body from the image data, extracting the peak of the luminance of the flat portion and the peak of the luminance of the uneven portion, and calculating the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion).

[0019] The appearance inspection method for the etching metal body of the present embodiment can be implemented, for example, using an appearance inspection device described below.

[0020] "Appearance inspection device" FIG. 1 is a side view schematically showing an appearance inspection device used in the appearance inspection method for the etching metal body of the present embodiment. FIG. 2 is a top view schematically showing the appearance inspection device used in the appearance inspection method for the etching metal body of the present embodiment. FIG. 3 is a top view schematically showing the appearance inspection device used in the appearance inspection method for a sheet-shaped etching metal body which is one of the present embodiments, showing a state in which a transport stage is rotated with respect to an inspection unit (a base unit that supports the inspection unit). FIG. 4 is a side view schematically showing the appearance inspection device used in the appearance inspection method for the etching metal body of the present embodiment, with an enlarged view of a support unit that supports a stage. FIG. 5 is a top view schematically showing the appearance inspection device used in the appearance inspection method for the etching metal body of the present embodiment, showing a state in which the stage is located at a first position. FIG. 6 is a top view schematically showing the appearance inspection device used in the appearance inspection method for the etching metal body of the present embodiment, showing a state in which the stage is located at a second position. The appearance inspection device 1 includes a base portion 10, a carrier stage 20, a stage 30, an illumination unit 40, and an imaging unit 50. The base portion 10 supports the carrier stage 20, the illumination unit 40, and the imaging unit 50. The base portion 10 has a rectangular outer shape with the direction along the X-axis (hereinafter referred to as the X-axis direction) being the long side and the direction along the Y-axis (hereinafter referred to as the Y-axis direction) being the short side. Hereinafter, the direction in which the long side of the base portion 10 extends is defined as the X-axis, the direction in which the short side of the base portion 10 extends is defined as the Y-axis, and the height direction is defined as the Z-axis for explanation.

[0021] The base portion 10 includes a rotation support portion 11 and a shaft support portion 12. The rotation support portion 11 supports the carrier stage 20 rotatably about a rotation axis L1 parallel to the Z-axis. The shaft support portion 12 supports each of the illumination unit 40 and the imaging unit 50 rotatably.

[0022] The carrier stage 20 supports the stage 30. The carrier stage 20 has a rectangular outer shape with the X-axis direction being the long side and the Y-axis direction being the short side. The rotation axis L1 is, for example, located at the center with respect to the long side of the carrier stage 20. The carrier stage 20 has a first part 20A on one side and a second part 20B on the other side with the center in the X-axis direction as the boundary.

[0023] The carrier stage 20 includes a rail portion 21. The rail portion 21 includes two rail members 21A and 21B extending along the long side of the carrier stage 20 (the X-axis direction in FIG. 1) from the first part 20A to the second part 20B. The rail portion 21 constitutes the movement path of the stage 30. The carrier stage 20 moves the stage 30 along the rail portion 21 by a first drive mechanism such as an electric actuator equipped with a motor or a pneumatic actuator equipped with a cylinder. The rail portion 21 and the first drive mechanism are an example of a transport unit for moving the stage 30 in a one-dimensional transport direction. The X-axis direction is an example of the transport direction in which the carrier stage 20 moves the stage 30. The transport direction coincides with the direction in which the long side of the carrier stage 20 extends.

[0024] The transfer stage 20 moves the stage 30 in a one-dimensional transfer direction between a predetermined first position in the first part 20A and a predetermined second position in the second part 20B. In FIG. 1, the stage 30 located at the first position and the metal body M for etching are shown by solid lines, and the stage 30 located at the second position and the metal body M for etching are shown by two-dot chain lines. Also, the first transfer direction D1 when the stage 30 moves from the first position toward the second position is indicated by a solid-line arrow. The second transfer direction D2 when the stage 30 moves from the second position toward the first position is indicated by a two-dot chain-line arrow.

[0025] The stage 30 includes a plate-like portion 31 having a placement surface 31S on which the metal body M for etching is placed, and an engaging portion 32 that engages with the rail portion 21. The stage 30 engages with the rail portion 21 through the engaging portion 32 so as to straddle the two rail members 21A and 21B constituting the rail portion 21. The material constituting the stage 30 is a non-magnetic metal or inorganic compound that is not attracted to a magnet. An example of the non-magnetic metal is aluminum or copper. The non-magnetic inorganic compound is silicon oxide or aluminum oxide. From the viewpoint of suppressing the deflection of the central portion due to its own weight, aluminum or an aluminum alloy having a high deformation resistance per unit weight is suitable for the stage 30. The thickness of the stage 30 is, for example, about 2 mm. The plate-like portion 31 has a placement surface 31S. The metal body M for etching is placed on the placement surface 31S.

[0026] The lighting unit 40 and the imaging unit 50 are arranged in the X-axis direction. The lighting unit 40 includes a first frame unit 41 and a line illumination 42. The first frame unit 41 is attached to the shaft support 12. The first frame unit 41 rotates with respect to the shaft support 12 about an axis parallel to the Y-axis as a rotation axis by a second drive mechanism such as a motor, for example. The line illumination 42 is attached to the tip of the first frame unit 41. The line illumination 42 irradiates the etching metal body M placed on the stage 30 moving along the rail unit 21 with the illumination light L, which is white illumination light, in a line shape. The line illumination 42 is, for example, an LED illumination linearly arranged along the Y-axis direction. The first frame unit 41 and the second drive mechanism are an example of an illumination drive unit that changes the irradiation angle of the illumination light L with respect to the etching metal body M by moving the line illumination 42.

[0027] The line illumination 42 condenses and irradiates the etching metal body M with the illumination light L so that the optical axis OA of the illumination light L is perpendicular to the light emitting surface 42S provided in the line illumination 42. The line illumination 42 is configured to be able to change the light quantity of the illumination light L. The line illumination 42 changes the light quantity of the illumination light L according to, for example, the magnitude of the applied voltage. Note that, for example, a mesh shutter may be used to change the light quantity of the illumination light L. The light quantity of the illumination light L decreases as the illumination light L passes through the mesh shutter. Therefore, the light quantity of the illumination light L may be changed by switching between a state where the mesh shutter is arranged on the optical path of the illumination light L and a state where the mesh shutter is not arranged on the optical path of the illumination light L. Alternatively, the light quantity of the illumination light L may be changed by switching the transmittance of the illumination light L using a liquid crystal shutter.

[0028] The imaging unit 50 is located on the side opposite to the lighting unit 40 with respect to the shaft support 12 in the X-axis direction. The imaging unit 50 includes a second frame unit 51 and a line camera 52. The second frame unit 51 is attached to the shaft support 12. The second frame unit 51 rotates with respect to the shaft support 12 about an axis parallel to the Y-axis as a rotation axis by a third drive mechanism such as a motor, for example.

[0029] The line camera 52 is attached to the tip of the second frame portion 51. The line camera 52 acquires the luminance of the reflected light when the illumination light L is reflected on the etching metal body M placed on the stage 30 that moves along the rail portion 21. In other words, the line camera 52 images so as to include the portion of the etching metal body M placed on the stage 30 that moves along the rail portion 21 and is irradiated with the illumination light L. In the XZ plane including the X-axis and the Z-axis, the imaging axis IA of the line camera 52 intersects the optical axis OA of the line illumination 42 at the intersection point P. The second frame portion 51 and the third drive mechanism are an example of a camera drive unit that changes the imaging angle of the line camera 52 with respect to the etching metal body M by moving the line camera 52.

[0030] The first frame portion 41 and the second frame portion 51 rotate with respect to the shaft support portion 12 around an axis that is parallel to the Y-axis and passes through the intersection point P as the rotation axis. That is, the rotation axis of the first frame portion 41 and the rotation axis of the second frame portion 51 overlap the intersection point P in the XZ plane. Therefore, the positions of the optical axis OA of the line illumination 42, the imaging axis IA of the line camera 52, and the intersection point P are constant regardless of the rotation angles of the first frame portion 41 and the second frame portion 51. The intersection point P is configured to be at the same height as the surface of the etching metal body M placed on the stage 30 that moves along the rail portion 21. The intersection point P is located, for example, on the rotation axis L1 in the XZ plane. The first frame portion 41 and the second frame portion 51 rotate separately with respect to the shaft support portion 12 so that the angle formed with the base portion 10 is in the range of more than 0 degrees and less than 180 degrees, for example.

[0031] By rotating at least one of the illumination unit 40 and the imaging unit 50 with respect to the base unit 10, the optical conditions when the metal body M for etching is imaged can be changed. For example, when the reflection angle of the illumination light L and the imaging angle of the line camera 52 coincide, the image acquired by the line camera 52 becomes a bright-field image. Also, when the reflection angle of the illumination light L and the imaging angle of the line camera 52 are different, the image acquired by the line camera 52 becomes a dark-field image. Further, by changing the amount of the illumination light L, the optical conditions when the metal body M for etching is imaged can also be changed.

[0032] The appearance inspection apparatus 1 includes a control device 100. The control device 100 includes, for example, a control unit and a storage unit. The control unit controls the operations of each part of the control device 100. The control unit is, as an example, a central processing unit (CPU). The control unit drives the carrier stage 20 to move the stage 30, for example. The control unit drives the first frame unit 41 to rotate the illumination unit 40 with respect to the shaft support portion 12. The control unit switches between a state where the line illumination 42 irradiates the illumination light L and a state where the line illumination 42 does not irradiate the illumination light L. The control unit changes the amount of the illumination light L irradiated by the line illumination 42. The control unit drives the second frame unit 51 to rotate the imaging unit 50 with respect to the shaft support portion 12. The control unit causes the metal body M for etching placed on the stage 30 moving along the rail portion 21 to be imaged by the line camera 52. The control unit processes the image data captured by the line camera 52. The control unit determines the presence or absence of defects in the metal body M for etching from the image data captured by the line camera 52.

[0033] The storage unit is, as an example, a hard disk drive (HDD). The storage unit stores, as an example, a program for controlling the operations of each part of the control device 100, the image data captured by the line camera 52, a program for processing the image data, and a program for determining the presence or absence of defects in the metal body M for etching from the image data.

[0034] As shown in FIG. 2, the metal body M for etching is placed on the placement surface 31S such that the long side is parallel to the conveyance direction. The conveyance table 20 moves the stage 30 from the first position to the second position or from the second position to the first position along the conveyance axis L2 passing through the center of the rail portion 21. At this time, the stage 30 passes through the imaging position between the first position and the second position. Note that the conveyance axis L2 is parallel to the conveyance direction in which the conveyance table 20 moves the stage 30. Further, in FIG. 2, a case where the conveyance axis L2 overlaps with the center line L4 passing through the center in the Y-axis direction in the base portion 10 is illustrated.

[0035] The line illumination 42 irradiates the illumination light L onto the metal body M for etching placed on the stage 30 passing through the imaging position of the conveyance table 20. The imaging position in the conveyance table 20 is a position where the illumination light L of the line illumination 42 is irradiated and imaged by the line camera 52 between the first position and the second position in the conveyance table 20. For example, the center of the imaging position is the intersection of the conveyance axis L2 and the center line L3 of the region irradiated with the illumination light L. Note that in FIG. 2, in a state where the stage 30 passes through the imaging position, the region irradiated with the illumination light L in the appearance inspection apparatus 1 is indicated by a two-dot chain line.

[0036] The line camera 52 images a line-shaped imaging region so as to include the portion of the metal body M for etching placed on the stage 30 passing through the imaging position in the conveyance table 20 that is irradiated with the illumination light L. That is, the imaging region of the line camera 52 overlaps with the region irradiated with the illumination light L of the line illumination 42. For example, in the X-axis direction, the center of the imaging region of the line camera 52 coincides with the center line L3 of the region irradiated with the illumination light L. Note that the center line L3 is a straight line parallel to the Y-axis.

[0037] Compared with an area camera that images the entire metal body M for etching at once, the distance between the line camera 52 and the metal body M for etching can be reduced by the amount by which the imaging region is small. Therefore, by using the line camera 52, the outer shape of the appearance inspection apparatus 1 can be made smaller than in the case of using an area camera.

[0038] The lighting unit 40 and the imaging unit 50 rotate with respect to the shaft support portion 12 about the center line L3 as the rotation axis. Therefore, regardless of the irradiation angle of the illumination light L with respect to the etching metal body M, the position of the region irradiated with the illumination light L in the appearance inspection apparatus 1 is constant. Similarly, regardless of the imaging angle with respect to the etching metal body M, the position of the imaging region in the appearance inspection apparatus 1 is constant. Note that the center line L3 passes through the intersection point P in FIG. 1 in the XZ plane.

[0039] As shown in FIG. 3, the rotation support portion 11 rotates the transport table 20 with respect to the base portion 10 about a rotation axis L1 parallel to the Z axis by a fourth drive mechanism such as a motor. The rotation axis L1 is an axis parallel to the Z axis passing through a point on the imaging position in the transport table 20 and is a perpendicular line to the XY plane. The rotation axis L1 is perpendicular to the placement surface 31S. The rotation axis L1 passes through, for example, the intersection of the transport axis L2 and the center line L3, which is the center of the imaging position. The rotation support portion 11 and the fourth drive mechanism are an example of a transport table drive portion that rotates the transport table 20 with respect to the line illumination 42 and the line camera 52 attached to the base portion 10.

[0040] The rotation support portion 11 rotates the transport table 20 with respect to the base portion 10 so that the angle θ1 formed by, for example, the transport axis L2 and the center line L4 passing through the center in the Y-axis direction in the base portion 10 is in the range of 0 degrees or more and 45 degrees or less. The center line L4 is a straight line parallel to the X axis. Further, the center line L4 coincides with the direction in which the lighting unit 40 and the imaging unit 50 are arranged in the base portion 10. In other words, the rotation support portion 11 rotates the transport table 20 with respect to the base portion 10 so that the angle θ2 formed by the transport axis L2 parallel to the transport direction and the center line L3 parallel to the Y-axis direction in which the illumination light L extends is in the range of 45 degrees or more and 135 degrees or less.

[0041] By rotating the transfer stage 20 with respect to the base portion 10, the direction in which the illumination light L is irradiated onto the metal body M for etching, and the direction in which the metal body M for etching is imaged can be changed with respect to the transfer direction in which the transfer stage 20 moves the stage 30. That is, by rotating the transfer stage 20 with respect to the base portion 10, the optical conditions when the metal body M for etching is imaged can be changed.

[0042] The long side of the transfer stage 20 is larger than the short side along the Y-axis direction of the base portion 10. Therefore, the larger the angle θ1 formed by the transfer axis L2 of the transfer stage 20 and the center line L4 of the base portion 10 approaches a right angle, the larger the width in the Y-axis direction of the appearance inspection apparatus 1 becomes. Accordingly, if the angle θ1 formed by the transfer axis L2 and the center line L4 is 0 degrees or more and 45 degrees or less, the width in the Y-axis direction of the appearance inspection apparatus 1 can be made smaller compared to a structure that rotates until the angle θ1 approaches 90 degrees.

[0043] The transfer stage 20 includes a support portion 22. The support portion 22 supports the stage 30 passing through the imaging position on the transfer stage 20 from below. The center of the support portion 22 coincides with, for example, the intersection of the transfer axis L2, which is the center of the imaging position, and the center line L3. By being supported by the support portion 22 when the stage 30 passes through the imaging position, the stage 30 can be kept in a flat state. Thereby, the metal body M for etching placed on the flat stage 30 can be imaged.

[0044] As shown in FIG. 4, the support portion 22 includes a magnet 22A and two non-magnetic portions 22B. In FIG. 4, dots are attached to the magnet 22A. The magnet 22A and the non-magnetic portions 22B extend in a direction intersecting the transfer direction. The magnet 22A is located between the two non-magnetic portions 22B in the transfer direction. Note that FIG. 4 shows a state in which the transfer direction coincides with the X-axis direction. The magnet 22A and the non-magnetic portions 22B support the plate-shaped portion 31 of the stage 30 from below so that the plate-shaped portion 31 does not bend due to its own weight and the weight of the metal body M for etching at the imaging position.

[0045] The magnet 22A is composed of a permanent magnet such as an alnico magnet, a ferrite magnet, or a neodymium magnet. The non-magnetic part 22B is a non-magnetic metal, an inorganic material, or a resin material such as polyacetal resin (POM). The support part 22 supports the stage 30 passing through the imaging position by the non-magnetic part 22B. When the metal body M for etching has ferromagnetism, the metal body M for etching can be attracted downward from below toward the mounting surface 31S by the magnetic force of the magnet 22A. Thereby, by suppressing the floating of the metal body M for etching with respect to the mounting surface 31S, the metal body M for etching in a flatter state can be imaged. Note that the thickness of the stage 30 is preferably 1 mm or more and 2 mm or less from the viewpoint of sufficiently applying the magnetic force of the magnet 22A to the metal body M for etching while maintaining mechanical strength. When the metal body M for etching has no magnetism, by placing a transparent substrate such as glass or a resin plate on the metal body M for etching, the floating of the metal body M for etching with respect to the mounting surface 31S is suppressed, and the metal body M for etching in a flatter state can be imaged.

[0046] The appearance inspection apparatus 1 inspects defects generated on the surface of the metal body M for etching in the manufacturing process of the metal body M for etching (the process before etching) and in the process after the etching process of the metal body M for etching. Defects generated in the metal body M for etching are, for example, scratch defects, stain defects, and hole defects. Scratch defects are scratches, dents, etc. caused by contact with a manufacturing apparatus, another metal plate, or the edge of a foreign object. For example, a long sheet-shaped metal plate such as the metal body M for etching may be manufactured by a roll-to-roll method in which it is unwound from a rolled state, processed, and then wound into a roll again. In the roll-to-roll method, scratches parallel to the winding direction (feeding direction), which is an example of scratch defects, are likely to be formed on the surface of the metal body M for etching. When detecting scratches parallel to the winding direction (feeding direction) of the metal body M for etching, it is preferable that the conveyance direction of the stage 30 is not parallel to the X axis along which the line illumination 42 and the line camera 52 are arranged, that is, the angle θ1 shown in FIG. 3 is more than 0 degrees and 45 degrees or less.

[0047] Stain defects are caused by contact between surfaces or chemical reactions with manufacturing equipment, other metal plates, or foreign substances. Stain defects include rust, discoloration due to chemical reactions, roughness on the surface, etc. Stain defects often have a lower degree of reflection of illumination light L compared to scratch defects. When detecting stain defects, for example, it is preferable to perform imaging in a dark field state.

[0048] Hole defects are shape defects of through-holes located in the central part of the etching metal body M. The through-holes are formed, for example, by chemical etching. Hole defects include, for example, cases where the through-holes are partially or entirely not formed, or the through-holes are too large or too small, or there are chips at the edges of the through-holes. Since the through-holes are parts where the etching metal body M penetrates in the thickness direction, the reflection mode when irradiated with illumination light L is different from other parts. Therefore, when detecting hole defects, it is preferable to have an optimal light amount so that the shape of the edge of the through-hole can be identified. Also, in order to clearly image the shape of the edge of the through-hole, it is preferable to image the reflected light that is specularly reflected by the etching metal body M with the line camera 52. That is, in the XZ plane shown in FIG. 1, it is preferable that the incident angle formed by the optical axis OA of the illumination light L and the rotation axis L1 is equal to the imaging angle formed by the imaging axis IA of the line camera 52 and the rotation axis L1.

[0049] As described above, multiple types of defects with different reflection modes may occur in the etching metal body M when irradiated with illumination light L. Also, depending on the shape and size of the defect, it may be difficult to identify on the image at a specific irradiation angle or shooting angle. That is, the optimal optical conditions for detecting defects occurring in the etching metal body M may vary depending on the type, size, shape, etc. of the defect.

[0050] Therefore, when performing an appearance inspection with the appearance inspection apparatus 1, the first to fifth imaging conditions for realizing the optimal optical conditions are determined according to the type and degree of the defect to be detected in advance. The imaging conditions are settings for each part in the appearance inspection apparatus 1 and are elements that determine the optical conditions when imaging the etching metal body M.

[0051] The first imaging condition is the magnitude of the irradiation angle of the illumination light L with respect to the metal body M for etching, that is, the magnitude of the angle of the first frame portion 41 with respect to the base portion 10 in the XZ plane. The second imaging condition is the magnitude of the imaging angle of the line camera 52 with respect to the metal body M for etching, that is, the magnitude of the angle of the second frame portion 51 with respect to the base portion 10 in the XZ plane. The third imaging condition is the magnitude of the angle θ1 of the conveyance direction of the stage 30 with respect to the X axis along which the line illumination 42 and the line camera 52 are arranged, that is, the magnitude of the angle θ1 of the conveyance table 20 with respect to the base portion 10 in the XY plane including the X axis and the Y axis. The fourth imaging condition is the exposure time with respect to the metal body M for etching passing through the imaging position. The exposure time depends on the conveyance speed at which the conveyance table 20 conveys the stage 30. The fifth imaging condition is the amount of the illumination light L with respect to the metal body M for etching passing through the imaging position.

[0052] The control device 100 stores at least one imaging condition pattern, which is a combination of the first to fifth imaging conditions. For example, the control device 100 stores, as the first imaging condition pattern, the combination of imaging conditions that is optimal for detecting defects. The control device 100 stores, as the second imaging condition pattern, the combination of imaging conditions that is optimal for detecting simulation defects. The control device 100 stores, as the third imaging condition pattern, the combination of imaging conditions that is optimal for detecting hole defects. Note that if a plurality of types of defects can be detected simultaneously by one imaging condition pattern, it is not necessarily required to store an imaging condition pattern for each type of defect. Also, for one type of defect, a plurality of imaging condition patterns may be stored to improve the detection accuracy. Each imaging condition pattern only needs to have at least one of the first to fifth imaging conditions different.

[0053] Hereinafter, an example of the appearance inspection method will be described with reference to FIGS. 5 and 6. As shown in FIG. 5, first, a sheet-shaped metal body M for etching is placed on the mounting surface 31S of the stage 30 located at the first position on the transfer table 20. Then, the control device 100 drives each part of the appearance inspection device 1 to apply an imaging condition pattern for detecting a desired defect. In this state, the transfer table 20 is driven to move the stage 30 along the first transfer direction D1 from the first position toward the second position. Then, when the stage 30 moves from the first position to the second position, illumination light L is irradiated from the line illumination 42 onto the metal body M for etching placed on the stage 30 passing through the imaging position. Further, the control device 100 adjusts the illuminance of the illumination light L so that the luminance of the flat part on the surface of the metal body M for etching becomes 100. Next, with the illumination light L whose illuminance has been adjusted as described above irradiated onto the surface of the metal body M for etching, and in a state where the reflected light of the illumination light L reflected from the surface of the metal body M for etching is obtained, the line camera 52 acquires image data of the surface of the metal body M for etching.

[0054] In the method for inspecting the appearance of the metal body for etching according to this embodiment, using the above-described appearance inspection apparatus 1, on the stage 30, the sheet-like metal body M for etching is arranged in three directions of -45°, 0°, and +45° clockwise with respect to the inspection unit, and it is preferable to acquire the image data of the surface of the sheet-like metal body M for etching. Specifically, it is preferable to arrange the metal body M for etching in three directions of -45°, 0°, and +45° clockwise with respect to the first conveyance direction D1, and acquire the image data of the surface of the metal body M for etching. Thereby, the optical conditions when imaging the metal body M for etching passing through the imaging position can be easily changed. Therefore, a plurality of images with changed optical conditions can be easily acquired according to the type of defect. In the case of a ferromagnetic material, it is necessary to appropriately adjust the timing of adsorption with a magnet, and in the case of a non-magnetic material, it is necessary to appropriately adjust the timing of placing a transparent substrate such as glass or a resin plate. In the method for inspecting the appearance of the metal body M for etching according to this embodiment, although the case of inspecting the appearance of the sheet-like metal body M for etching is described, when performing the appearance inspection while the metal body M for etching is in a roll (wound-up) state, it is preferable to arrange the inspection unit in three directions of -45°, 0°, and +45° clockwise with respect to the roll-shaped metal body M for etching, and acquire the image data of the surface of the metal body M for etching. When cutting from the roll-shaped metal body for etching into a sheet shape and performing the appearance inspection, similar to the case of inspecting the appearance of the roll-shaped metal body M for etching, the inspection unit may be arranged in three directions of -45°, 0°, and +45° clockwise with respect to the sheet-like metal body M for etching, and the image data of the surface of the metal body M for etching may be acquired.

[0055] In the method for inspecting the appearance of the metal body for etching according to this embodiment, the angle A (the angle formed by the optical axis of the illumination light L of the line illumination 42 with respect to the surface of the metal body M for etching) at which the illumination light L is incident on the vertical surface (the surface H perpendicular to the depth from the front in FIG. 1) of the surface of the metal body M for etching, and the angle B (the angle formed by the imaging axis IA of the line camera 52 with respect to the vertical surface of the surface of the metal body M for etching) at which the reflected light is received by the line camera 52 with respect to the vertical surface (the surface H perpendicular to the depth from the front in FIG. 1) of the surface of the metal body M for etching are preferably less than 90°, but more preferably 60° or less and even more preferably 50° or less due to the design specifications of the appearance inspection apparatus. When the angle A and the angle B are 60°, the contrast for detecting defects in all three directions of -45°, 0°, and +45° clockwise with respect to the winding direction (feeding direction) of the metal body M for etching is strong, but there is a lot of noise. On the other hand, when the angle A and the angle B are between 20° and 40°, it is difficult to detect defects well in all three directions of -45°, 0°, and +45° clockwise with respect to the winding direction (feeding direction) of the metal body M for etching.

[0056] In the method for inspecting the appearance of the metal body for etching according to this embodiment, it is preferable that the angle A and the angle B are different in order to detect defects with the line camera 52 at an angle not affected by the direct reflection from the illumination light L. When the angle A and the angle B are different, in view of the design specifications considering the three-dimensional obstacles of the appearance inspection apparatus, it is preferable that the angle A is 16° or more and 56° or less, and the angle B is 20° or more and 60° or less, more preferably the angle A is 26° or more and 56° or less, and the angle B is 30° or more and 60° or less, and even more preferably the angle A is 36° or more and 56° or less, and the angle B is 40° or more and 60° or less. Thereby, it is possible to detect defects well in all three directions of -45°, 0°, and +45° clockwise with respect to the winding direction (feeding direction) of the metal body M for etching.

[0057] In the method for inspecting the appearance of the metal body for etching according to the present embodiment, it is preferable that the difference between the angle A and the angle B is 1° or more and 10° or less, more preferably 2° or more and 7° or less, and even more preferably 3° or more and 5° or less. Thereby, defects can be detected by the line camera 52 at an angle that is not affected by specular reflection from the illumination light L.

[0058] As shown in FIG. 6, the stage 30 is located at the second position of the carrier 20 in the state where the imaging is completed. Next, the control device 100 acquires a luminance profile of the surface of the metal body M for etching over the flat portions and the uneven portions on the surface of the metal body M for etching from the obtained image data, and extracts the luminance peak of the flat portion and the luminance peak of the uneven portion on the surface of the metal body M for etching, and calculates the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion).

[0059] If the obtained luminance difference is less than 60, it can be determined that the metal body M for etching has excellent flatness.

[0060] According to the method for inspecting the appearance of the metal body for etching of the present embodiment, since the luminance peak of the flat portion and the luminance peak of the uneven portion are extracted on the surface of the metal body M for etching, and the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion) is calculated, the flatness of the metal body for etching can be easily analyzed.

Example

[0061] Hereinafter, the present invention will be described more specifically with reference to experimental examples, but the present invention is not limited to the following experimental examples.

[0062] [Experimental Example 1] Nine stainless alloy plates (SUS304) with a thickness of 25 μm having fine uneven portions on the surface were prepared. The displacement amount on the surface of these stainless alloy plates (depth of the concave portion with respect to the flat portion, height of the convex portion with respect to the flat portion) was measured using a contact type digital length measuring instrument (product name: Digimicro MH-15, manufactured by Nikon Corporation). The results are shown in Table 1.

[0063] [Experimental Example 2] The displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 (the depth of the concave portion based on the flat portion, the height of the convex portion based on the flat portion) was measured using a laser microscope (product name: VK-X1100, manufactured by Keyence Corporation). The results are shown in Table 1.

[0064] [Experimental Example 3] The displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 (the depth of the concave portion based on the flat portion, the height of the convex portion based on the flat portion) was measured using a laser microscope (product name: OLS5100, manufactured by Olympus Corporation). The results are shown in Table 1.

[0065] [Experimental Example 4] The displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 (the depth of the concave portion based on the flat portion, the height of the convex portion based on the flat portion) was measured using a CNC image measuring instrument (product name: QV-ACCEL808, manufactured by Mitutoyo Corporation). The results are shown in Table 1.

[0066] [Experimental Example 5] The displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 (the depth of the concave portion based on the flat portion, the height of the convex portion based on the flat portion) was evaluated using the appearance inspection device shown in FIG. 1. The results are shown in Table 1. In Table 1, "×" indicates that measurement is impossible.

[0067]

Table 1

[0068] From the results shown in Table 1, it was found that when the displacement amount of the surface of the stainless steel alloy plate is 20 μm or less, it is difficult to measure the displacement amount with the contact type digital length measuring instrument of Experimental Example 1, the laser microscope of Experimental Example 2, and the CNC image measuring instrument of Experimental Example 4. Further, with the laser microscope of Experimental Example 3, even when the displacement amount of the surface of the stainless steel alloy plate is 20 μm or less, the displacement amount can be measured, but it becomes a destructive inspection after sheet cutting. In contrast, the appearance inspection device of Experimental Example 5 can image the displacement amount on the surface of the stainless alloy plate, and it was found that there is a difference in luminance between the flat part (flat part without deformation) and the uneven part (deformed part) of the image data. Also, when rotating the inspection unit, inspection (non-destructive inspection) can be continuously carried out without cutting while remaining in a roll shape. Of course, destructive inspection by sheet cutting is also possible. It was also found that there is a correlation between the displacement amount and the luminance difference. Note that, although the displacement amounts of the same sample (stainless alloy plate) were measured, the different measurement results are considered to be due to different measurement positions.

[0069] [Experimental Example 6] Using the appearance inspection device shown in FIG. 1, the imaging conditions under which the contrast of the uneven parts on the surface of the metal body for etching is the highest were investigated. Here, as the imaging conditions, the angle A at which white illumination light is incident on the surface of the metal body for etching (the angle formed by the optical axis of the line illumination with respect to the vertical plane of the surface of the metal body for etching), and the angle B at which reflected light is received with respect to the surface of the metal body for etching (the angle formed by the imaging axis of the line camera with respect to the vertical plane of the surface of the metal body for etching) were evaluated. The above angle A and the above angle B were changed to (angle A: 16°, angle B: 20°), (angle A: 26°, angle B: 30°), (angle A: 36°, angle B: 40°), (angle A: 46°, angle B: 50°), (angle A: 56°, angle B: 60°). Also, the metal body for etching was arranged in three directions of -45°, 0°, and +45° clockwise with respect to the inspection unit. Under such conditions, using the appearance inspection device, the surface of the metal body for etching was imaged, and image data of the surface of the metal body for etching was acquired. The results are shown in FIG. 7. From the results shown in FIG. 7, it was found that the larger the above angle A and the above angle B, the higher the contrast of the uneven parts. However, when the contrast of the uneven parts becomes the highest when angle B is 60°, noise increases, so the optimal value of angle B is considered to be 50°. Accordingly, the optimal value of angle A is considered to be 46°.

[0070] [Experimental Example 7] The displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 (the depth of the concave portion based on the flat portion, the height of the convex portion based on the flat portion) was measured in the same manner as in Experimental Example 4. Further, the displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 was evaluated in the same manner as in Experimental Example 5. The image data captured by the line camera (see Fig. 8) was transferred to a personal computer and displayed using image display software, and the luminance profile was obtained so as to straddle the flat portion and the uneven portion (the short axis direction when approximating the defect as an ellipse), and the luminance peak of the uneven portion and the luminance peak of the flat portion were extracted. As shown in Fig. 8, the displacement amount between P and Q was measured on the surface of the stainless steel alloy plate. The illuminance of the white illumination light was adjusted so that the luminance of the flat portion became 100, and the luminance difference (luminance of the flat portion - luminance of the uneven portion) was calculated. The results are shown in Fig. 9. From the results shown in Fig. 9, it was found that the luminance of the uneven portion was higher than the luminance of the flat portion. In addition, Fig. 10 shows the relationship between the displacement amount of the surface of the stainless steel alloy plate measured in the same manner as in Experimental Example 4 and the displacement amount and luminance difference of the surface of the stainless steel alloy plate measured as described above. Fig. 10 also shows the equation of the straight line approximately representing the distribution of the measurement results of the displacement amount of the surface of the stainless steel plate and the luminance difference of the surface of the stainless steel alloy plate. From the results shown in Fig. 10, it was found that there was a correlation between the displacement amount of the surface of the stainless steel alloy plate and the luminance difference of the surface of the stainless steel alloy plate.

[0071] [Experimental Example 8] The displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 (the depth of the concave portion based on the flat portion, the height of the convex portion based on the flat portion) was measured in the same manner as in Experimental Example 4. Further, the displacement amount of the surface of the stainless steel alloy plate similar to that in Experimental Example 1 was evaluated in the same manner as in Experimental Example 5. The evaluation of the displacement amount was performed on 10 samples. For 10 samples for which the displacement was evaluated, etching was performed on a 25-μm thick stainless steel alloy plate (SUS304) by the following method to produce a metal mask in a matrix shape with small openings of 30 μm × 30 μm and a pitch of 60 μm. A 25-μm thick stainless steel alloy plate (SUS304) was prepared, resist patterning was performed on both the front and back surfaces, and two-step etching was carried out in the order of small openings and large openings with an acid (ferric chloride) solution. The portion where the large opening and the small opening are connected is the connection part. In a cross-section along the thickness direction of the metal mask and passing through the connection part, a straight line (normal line) perpendicular to the small opening and the large opening is the reference line. In this cross-section, the straight line passing through the edge of the large opening and the connection part is the inclined line. And the angle (taper angle) formed by the reference line and the inclined line was 50° and the step height was 0.7 μm. Regarding the obtained metal mask, the presence or absence of etching defects was confirmed by a CNC image measuring instrument (product name: QV-ACCEL808, manufactured by Mitutoyo Corporation) for the shape of the small openings. The results are shown in Table 2. Also, the images of the metal mask after etching are shown in Figs. 11 to 14.

[0072]

Table 2

[0073] From the results shown in Table 2, the displacement amount at the time when etching defects occurred was 10 μm, and the luminance difference evaluated by the appearance inspection device at that time was 60. From this, it was determined that NG if the luminance difference was 60 or more. Since the result shown in Fig. 9 has a luminance difference of 65, it is a defective case. When etching defects occur, as shown in Fig. 11, the mode is such that the dimensions of the small opening itself increase. As shown in Figs. 12 and 13, the small opening part becomes a trailing mode (a part becomes larger), and as shown in Fig. 14, the mode is such that a part of the dimensions of the small opening becomes smaller. When a liquid resist is used, if there are convex portions on the surface of the stainless steel alloy plate, a mode in which the dimensions of the small opening itself increase or a trailing mode of the small opening part (a part becomes smaller) occurs. If there are concave portions on the surface of the stainless steel alloy plate, the thickness of the resist becomes locally thick, and a mode in which a part of the dimensions of the small opening becomes smaller occurs.

[0074] In addition, when performing an appearance inspection of the roll-shaped metal body for etching, inspection parts arranged in three directions of -45°, 0°, and +45° clockwise with respect to the metal body for etching can also be provided at three locations along the direction in which the metal body for etching is fed out. For example, the two inspection parts other than the inspection part arranged at 0° clockwise with respect to the metal body for etching M may have an angle adjustment mechanism so that the angle with respect to the metal body for etching M can be adjusted.

[0075] The method for inspecting the appearance of the metal body for etching according to the present invention enables not only the appearance inspection of the metal body before etching but also the appearance inspection of the metal body after etching.

Explanation of Reference Numerals

[0076] L Illumination light L1 Rotation axis L2 Conveying axis 1 Appearance inspection device 10 Base part (the part below the inspection part) 20 Conveying table 21 Rail part 22 Support part 22A Magnet 30 Stage 31 Plate-shaped part 31S Mounting surface 40 Illumination part 41 First frame part 42 Line illumination 50 Imaging part 51 Second frame part 52 Line camera 100 Control device

Claims

1. An etching metal body used for forming an etching pattern, wherein the difference between the luminance of the flat portion and the luminance of the uneven portion on the surface of the etching metal body is less than 60, and the luminance is measured by the following appearance inspection method of the etching metal body. An etching metal body. (Appearance inspection method of etching metal body) Irradiate the surface of the etching metal body with white illumination light, adjust the illuminance of the white illumination light so that the luminance of the flat portion on the surface of the etching metal body becomes 100, irradiate the surface of the etching metal body with white illumination light, and in a state where the reflected light of the white illumination light reflected on the surface of the etching metal body is obtained, acquire the image data of the surface of the etching metal body with an inspection unit, and from the image data, across the flat portion and the uneven portion on the surface of the etching metal body, acquire the luminance profile of the surface of the etching metal body, extract the peak of the luminance of the flat portion and the peak of the luminance of the uneven portion, and calculate the difference in luminance between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion).

2. The etching metal body according to claim 1, wherein the thickness of the etching metal body is 5 μm or more and 50 μm or less.

3. The etching metal body according to claim 1, wherein the etching metal body is an iron-based metal.

4. The etching metal body according to claim 3, wherein the iron-based metal is made of a stainless alloy, an iron-nickel alloy, or an iron-nickel-cobalt alloy.

5. An appearance inspection method for the surface of an etching metal body used for forming an etching pattern, comprising: irradiating the surface of the etching metal body with white illumination light and adjusting the illuminance of the white illumination light so that the luminance of the flat portion on the surface of the etching metal body becomes 100; and irradiating the surface of the etching metal body with white illumination light and acquiring, with an inspection unit, image data of the surface of the etching metal body in a state where the reflected light of the white illumination light reflected on the surface of the etching metal body is obtained. A step of obtaining a luminance profile of the surface of the metal body for etching over the flat portion and the uneven portion on the surface of the metal body for etching from the image data, extracting the luminance peak of the flat portion and the luminance peak of the uneven portion, and calculating the luminance difference between the flat portion and the uneven portion (luminance of the flat portion - luminance of the uneven portion), and an appearance inspection method for a metal body for etching having the same.

6. The method for inspecting the appearance of a metal body for etching according to claim 5, wherein the metal body for etching is arranged in three directions of -45°, 0°, and +45° clockwise with respect to the inspection unit to obtain image data of the surface of the metal body for etching.

7. The method for inspecting the appearance of a metal body for etching according to claim 5, wherein the inspection unit is arranged in three directions of -45°, 0°, and +45° clockwise with respect to the metal body for etching to obtain image data of the surface of the metal body for etching.

8. The method for inspecting the appearance of a metal body for etching according to claim 5, wherein an angle A formed by the white illumination light incident on the surface of the metal body for etching and the vertical plane of the metal body for etching, and an angle B formed by the reflected light received from the surface of the metal body for etching and the vertical plane of the metal body for etching are less than 90°.

9. The method for inspecting the appearance of a metal body for etching according to claim 8, wherein the angle A and the angle B are different.

10. The method for inspecting the appearance of a metal body for etching according to claim 8, wherein the difference between the angle A and the angle B is 1° or more and 10° or less.

Images