JP2017015815A - Light shielding member and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light shielding member improved in light shielding performance and a method for manufacturing the same.SOLUTION: A light shielding member 21 includes a base material sheet 37 made of aluminium, and a light shielding layer 38. The light shielding layer 38 is formed individually on a first sheet surface 41, a second sheet surface 42, a sheet inner peripheral surface 43, and a sheet outer peripheral surface of the base material sheet 37. The light shielding layer 38 has a plurality of conical protrusions 46 disposed at pitches equal to or less than a wavelength of incident light. The plurality of protrusions 46 are formed to make their tip orientations ununiform. The pitches of the plurality of protrusions 46 are set to equal to or less than the wavelength of the incident light.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a light shielding member and a method for manufacturing the same.

  As a light shielding member used in various optical devices, there is a so-called light shielding film in the form of a film. For example, Patent Document 1 describes a light-shielding film in which a resin component contains a black pigment and amorphous silica having an average particle diameter of 3 μm or more and 10 μm or less. The light-shielding film has irregularities formed on the surface, and when the periphery is punched, irregularities having a surface roughness (arithmetic average height Ra) of 1 μm or more are formed on the end surfaces. Patent Document 2 describes a light shielding film in which a resin component contains a black pigment and a direction filler, and a cavity is formed inside. This light-shielding film has a void content of 10 to 50% by volume, and irregularities of 0.2 to 2.2 μm in surface roughness (arithmetic average height Ra) are formed on both film surfaces.

  In addition, as a light shielding member, a plurality of cone-shaped protrusions are formed at a pitch equal to or smaller than the wavelength of incident light, and a member that prevents reflection of incident light by these protrusions is also known. The pitch of the protrusions is on the order of nanometers (nm), and the concavo-convex structure in which a plurality of such protrusions are formed is also called a moth-eye structure.

  For example, in a lens unit composed of a plurality of lenses, the light shielding member as described above blocks light unrelated to photographing, such as preventing stray light from entering the lens.

JP 2012-194514 A JP 2013-190500 A

  However, when the light shielding films of Patent Document 1 and Patent Document 2 are used, for example, in the lens unit as described above, incident light is scattered at the end surface, so that the end surface looks black, but the light shielding performance. For example, when used in a lens unit, stray light still remains and improvement in the light shielding performance is desired.

  An object of this invention is to provide the light-shielding member which improved the light-shielding performance, and its manufacturing method.

  In order to solve the above-described problems, the present invention provides a light shielding member having a plurality of cone-shaped projections arranged at a pitch equal to or less than the wavelength of incident light, and the plurality of projections are formed with a nonuniform tip direction. It is configured as a feature.

  The light shielding member preferably includes a base sheet and a light shielding layer provided on the surface of the base sheet and having a plurality of protrusions.

  It is preferable that the end surface of the base sheet has an intersecting surface that intersects the thickness direction of the base sheet. When the light shielding member is viewed from the direction perpendicular to the sheet surface of the base sheet, the width of the end of the light shielding member formed from the end surface is preferably at least 50% of the thickness of the light shielding member.

  The manufacturing method of the light shielding member of the present invention includes a sheet forming step and a light shielding layer forming step, and the light shielding member has a plurality of cone-shaped protrusions arranged at a pitch equal to or less than the wavelength of incident light. In the sheet forming step, a base sheet is formed from the sheet material. The light shielding layer forming step forms a light shielding layer having a plurality of protrusions on the surface of the base sheet. In the light shielding layer forming step, a plurality of protrusions whose tip directions are not uniform are formed by plating on the surface of the base sheet.

  In the sheet forming step, it is preferable to form an intersecting surface intersecting the thickness direction of the base sheet as at least a part of the end face of the base sheet by photoetching on the sheet material.

  The light shielding member of the present invention is excellent in light shielding performance, and according to the method for producing a light shielding member of the present invention, a light shielding member excellent in light shielding performance can be produced.

It is a schematic diagram showing an example of an imaging module using a light shielding member. It is a perspective view of the light shielding member of a 1st embodiment. It is an end elevation of the section in the inner peripheral surface of a shading member, and its neighborhood. It is explanatory drawing of the pitch of a protrusion. It is explanatory drawing of the height of a protrusion. It is explanatory drawing of direction of the front-end | tip of a protrusion. It is explanatory drawing of the formation method of a base material sheet. It is a perspective view of the sheet material in which the base material sheet was formed. It is the schematic of a plating processing apparatus. It is an end elevation of the section in the inner peripheral surface of the light-shielding member of a 2nd embodiment, and its neighborhood. It is explanatory drawing of the light shielding member of 2nd Embodiment. It is an end elevation of the section in the inner skin of the shading member of a 3rd embodiment, and its neighborhood. It is an end elevation of the section in the inner skin of the light-shielding member of a 4th embodiment, and its neighborhood. It is a schematic perspective view of a sheet material and an etching mask. It is explanatory drawing of an etching step. It is sectional drawing of the base material sheet and light shielding layer of the light shielding member of 5th Embodiment. It is the schematic of an electrolytic surface roughening processing apparatus.

[First Embodiment]
In FIG. 1, a photographing module 10 includes a lens unit 11, an image sensor (image sensor) 12, and the like, and is built in, for example, a smartphone or a mobile phone. The lens unit 11 includes four lenses 16 to 19, four light shielding members 21 to 24, a lens barrel 27 in which these lenses 16 to 19 and the light shielding members 21 to 24 are incorporated. In this example, the number of lenses is four, but the number is not limited to four, and may be increased or decreased as appropriate according to the lens design. The light shielding members 21 to 24 are ring-shaped sheets, and are arranged between the lens 16 and the lens 17, the lens 17 and the lens 18, the lens 18 and the lens 19, and the light exit surface side of the lens 19, Block light unrelated to shooting. Each of the light shielding members 21 to 24 has a size corresponding to an adjacent lens.

  The image sensor 12 is mounted on a substrate 28, and the lens unit 11 is fixed to the substrate 28. The lens 16 includes a convex aspheric surface 16a that is axisymmetric with respect to the optical axis on the first surface side, a flat surface 16b on the second surface side, and an edge 16c on the outer peripheral side of the aspheric surface 16a. The subject light incident on the spherical surface 16 a passes through the lens 16, the lens 17, the lens 18, and the lens 19 in order and forms an image on the imaging surface of the imaging device 12 to be imaged.

  Since the light shielding members 21 to 24 have the same configuration except for the outer diameter and the inner diameter, the light shielding member 21 will be specifically described below, and the description of the light shielding members 22 to 24 will be omitted. As shown in FIG. 2, the light shielding member 21, which is a sheet formed in a ring shape, has an outer diameter of 5 mm, an inner diameter of 1.8 mm, and a thickness T of 20 μm in this example. However, the outer diameter, inner diameter, and thickness are not limited to this. Of the surface of the light shielding member 21, reference numeral 31 is assigned to the first member surface directed toward the light incident side into the lens barrel 27, and the second member surface directed toward the image sensor 12 in the lens barrel 27. Is denoted by reference numeral 32, the inner peripheral surface which is the inner end face is indicated by reference numeral 33, and the outer peripheral face which is the outer end face is indicated by reference numeral 34.

  As shown in FIG. 3, the light shielding member 21 includes a base sheet 37 and a light shielding layer 38. The base material sheet 37 is a member main body of the light shielding member 21, and the light shielding layer 38 is for improving the light shielding performance as the light shielding member 21 by supplementing the light shielding function of the base material sheet 37. The light shielding performance is the performance of blocking light, and the blocking here is mainly due to absorption. The base sheet 37 is a ring-shaped sheet similar to the light shielding member 21, and includes a first sheet surface 41, a second sheet surface 42, a sheet inner peripheral surface 43 that is an inner end surface, and an outer periphery that is an outer end surface. And a surface (not shown). A light shielding layer 38 is provided on each of the first sheet surface 41, the second sheet surface 42, the sheet inner peripheral surface 43, and the sheet outer peripheral surface, and is formed as a covering layer that covers the surface of the base sheet 37. Therefore, the light shielding layer 38 on the first sheet surface 41 is the first member surface 31, the light shielding layer 38 on the second sheet surface 42 is the second member surface 32, and the light shielding layer 38 on the sheet inner peripheral surface 43 is the inner surface. The peripheral surface 33 and the light shielding layer 38 on the outer peripheral surface of the sheet form the outer peripheral surface 34, respectively. In the case where the outer peripheral surface 34 is in close contact with the inner wall of the lens barrel 27 as in the lens unit 11 shown in FIG. 1, it is not necessary to provide the light shielding layer 38 on the outer peripheral surface 34, but the light shielding member 21 in this example is the outer peripheral surface. 34 also has a light shielding layer 38 formed thereon. However, since the light shielding member 21 of this example is manufactured by the manufacturing method described later, the light shielding layer 38 is not formed on a part of the outer peripheral surface 34.

  Since the light shielding layer 38 is provided on the sheet inner peripheral surface 43 in addition to the first sheet surface 41 and the second sheet surface 42 as described above, the light shielding layer 38 is formed on the first sheet surface 41 and the second sheet surface 42. Compared to the case of providing only, incident light and stray light are reliably received and absorbed. Reliable reception and absorption of incident light and stray light are not limited to the case where the directions of the tips are formed non-uniformly, like a plurality of protrusions 46 of this embodiment described later. That is, the light shielding layer having a concavo-convex structure formed by the protrusions being arranged at a pitch less than the wavelength of the incident light includes the sheet inner peripheral surface 43 in addition to the first sheet surface 41 and the second sheet surface 42. The incident light and the stray light are surely received and absorbed as compared to the case where only the first sheet surface 41 and the second sheet surface 42 are provided.

  The base sheet 37 is made of aluminum (Al) in this example, but may be made of other materials. Moreover, the base sheet 37 may be formed from a mixture of two or more different materials. For example, when the mass of the base sheet 37 is 100, the mass of aluminum is in the range of 98.3 to 99.9, and the mass of other materials is in the range of 0.1 to 1.7. Also good. The material of the base sheet 37 may be transparent or opaque, but is preferably as low as possible in the incident light incident on the light shielding member 21, for example, metal. Preferred metals include copper (Cu), tin (Sn), SUS (stainless steel) and the like. However, even a metal such as aluminum transmits light depending on the thickness and reflects light on the surface, and therefore the light shielding layer 38 is provided on the base sheet 37.

  The light shielding layer 38 has a plurality of protrusions 46, and the first member surface 31, the second member surface 32, the inner peripheral surface 33, and the outer peripheral surface 34 are formed by closely arranging these protrusions 46. It has a concavo-convex structure (hereinafter referred to as a surface concavo-convex structure). In this example, the protrusion 46 has a conical shape whose diameter decreases toward the tip. However, the protrusion 46 may be a tapered so-called cone shape, and may be a pyramid shape instead of the cone shape. Further, the tip of the projection 46 does not need to be sharp and may be rounded. Thus, since each of the protrusions 46 has a cone shape, the first member surface 31, the second member surface 32, the inner peripheral surface 33, and the outer peripheral surface 34 have a moderate refractive index with respect to incident light. For this reason, the absorption rate of incident light increases.

  The pitch (hereinafter referred to as the protrusion pitch) PS of the plurality of protrusions 46 is set to be equal to or less than the wavelength of the incident light. The protrusion pitch PS is a distance between the apexes of the adjacent protrusions 46. Further, below the wavelength of incident light means that it is below the shortest wavelength among the wavelength bands of incident light.For example, when the wavelength band of incident light is in the visible light region and the shortest wavelength is 400 nm, The protrusion pitch PS is 400 nm or less. The protrusion pitch PS need not be constant, and is not constant in this embodiment. When the protrusion pitch PS is non-uniform in this way, the distance between the respective apexes (PS1, PS2, PS3,...) Of 11 adjacent protrusions 46 as shown in FIG. PS8, PS9, PS10) is obtained, and the average value obtained by (PS1 + PS2 + PS3 +... + PS8 + PS9 + PS10) / 10 is defined as the protrusion pitch PS. The distances (PS1, PS2, PS3,..., PS8, PS9, PS10) between the tops can be obtained by observing the cross section of the light shielding layer 38 with an SEM (Scanning Electron Microscope). The protrusion pitch PS in the present embodiment is 300 nm. In FIG. 4A, the vertical direction is the thickness direction, and the first member surface 31 is shown. The protrusion pitch PS is more preferably shorter than the shortest wavelength of incident light, and more preferably shorter than ½ of the shortest wavelength.

  The height of the protrusion 46 (hereinafter referred to as the protrusion height) HS is not less than 1/4 of the longest wavelength in the wavelength band of incident light. The protrusion height HS is a distance from the bottom surface B46 of the protrusion 46 to the top. When the wavelength band of incident light is in the visible light region, the protrusion height HS is 200 nm or more when the longest wavelength is 800 nm. The height HS of the protrusion 46 may be constant or non-uniform. In the present embodiment, the protrusion height HS is not uniform. When the protrusion height HS is non-uniform in this way, the distance from the bottom surface to the top (HS1, HS2, HS3,...) For each of the ten adjacent protrusions 46 as shown in FIG. .., HS8, HS9, HS10), and the average value obtained by (HS1 + HS2 + HS3 +... + HS8 + HS9 + HS10) / 10 is defined as the protrusion height HS. The distances (HS1, HS2, HS3,..., HS8, HS9, HS10) from the bottom surface to the top of each protrusion 46 can be obtained by observing the cross section of the light shielding layer 38 with the SEM described above. The protrusion height HS in the present embodiment is 500 nm.

  The surface uneven structure formed by the plurality of minute protrusions 46 as described above is also called a moth-eye structure. In the moth-eye structure, the volume ratio between the material of the protrusions 46 and the light medium that occupies between the adjacent protrusions 46 gradually changes from the tip of the protrusions 46 toward the root, so that apparent refraction The rate changes slowly. Therefore, incident light is less likely to be reflected or refracted and is absorbed by the light shielding layer 38. Note that the medium in this example is air.

  As shown in FIG. 6, the plurality of protrusions 46 are formed so that the directions of the tips are not uniform. That is, the directions of the tips of the plurality of protrusions 46 are random. The direction of the tip is the direction from the bottom surface 46b to the top portion 46p when the perpendicular P is lowered from the top portion 46p of the protrusion 46 to the bottom surface 46b. In this way, since the plurality of protrusions 46 are formed with the tip directions being non-uniform, the apparent refractive index changes more reliably and gradually, and incident light is more reliably absorbed.

  In this example, the light shielding layer 38 contains nickel (Ni) and is black. By making it black, incident light is absorbed more and the light shielding performance is more reliably improved. Nickel is preferably contained in a mass of at least 80 when the mass of the light shielding layer 38 is 100. Since the light shielding layer 38 is black, the light shielding member 21 can be used for decorative purposes, for example, using this black color.

  The method for manufacturing the light shielding member 21 includes a sheet forming step for forming the base sheet 37 and a light shielding layer forming step for forming the light shielding layer 38 on the surface of the base sheet 37. In the sheet forming step, the base sheet 37 is formed from an aluminum sheet material. As shown in FIG. 7, the sheet material 50 is punched out so as to leave a base sheet 37 and a bridge 50 b that holds each base sheet 37. In this example, the sheet material 50 capable of forming a plurality of base material sheets 37 is used, but the size of the sheet material 50 is not particularly limited. The number of substrate sheets 37 formed by one punching may be one or more. Further, a plurality of sheet materials 50 may be punched by overlapping in the thickness direction. In such a punching method, the base material sheet 37 is formed on the sheet material 50 by cutting the sheet material 50 with a cutting blade or the like. The base sheet 37 may be formed by punching or photoetching as in this embodiment, but the sheet inner peripheral surface 43 and the sheet outer peripheral surface are perpendicular to the first sheet surface 41 and the second sheet surface 42. From the viewpoint of forming the film, punching is easier, and the production efficiency is also excellent.

  In the present embodiment, 16 substrate sheets 37 are formed on the sheet material 50 as shown in FIG. In the light shielding layer forming step, the sheet material 50 is plated. Examples of the plating treatment include electrolytic plating and electroless plating. An apparatus used for electrolytic plating includes a plating apparatus 61 shown in FIG. The plating apparatus 61 includes an electrolytic cell 62, an electrode 63, and a DC power source 64, and an electrolytic solution 65 is accommodated in the electrolytic cell 62. The electrolytic solution 65 contains nickel.

  The electrode 63 is disposed in the electrolytic solution 65. Similarly to the electrode 63, the sheet material 50 on which the base sheet 37 is formed is arranged in the electrolytic solution 65, and the sheet material 50 is immersed facing the electrode 63. The sheet material 50 is connected to the cathode of the DC power supply 64, and the electrode 63 is connected to the anode. The surface of the sheet material 50, that is, the surface of each base material sheet 37 and the surface of the bridge 50 b is subjected to a plating process by a direct current flowing from the DC power supply 64, thereby forming a light shielding layer 38 (see FIG. 3).

  The light shielding member 21 is obtained by separating the portion of the base sheet 37 from the bridge 50b from the sheet 50 subjected to the plating treatment. As described above, when the light shielding member 21 is obtained by separating from the bridge 50b, the light shielding layer 38 is not formed on the portion of the outer peripheral surface of the base sheet 37 separated from the bridge 50b. The light shielding layer 38 is formed in the portion.

  The light shielding layer forming step may be an electroless plating process instead of the above electrolytic plating process. Examples of the electroless plating treatment include Ni-P (nickel-phosphorus) plating using phosphinate as a reducing agent. More specifically, using a plating bath made of nickel sulfate, sodium phosphinate, and sodium acetate, the sheet material 50 on which the base sheet 37 is formed is immersed in this plating bath, and Ni—P ( A coating film made of nickel and phosphorus is formed. In this case, the hydrogen ion exponent pH of the plating bath is preferably in the range of 4 to 6, and the temperature of the plating bath is preferably 90 ° C. When the obtained coating film is obtained as a target surface uneven structure, this coating film may be used as the light shielding layer 38. When the obtained coating film is different from the target surface uneven structure such as when it is smooth, the target surface uneven structure is obtained by etching the coating film in sulfuric acid or acetic acid. The light shielding layer 38 is formed. In the case where the light shielding layer 38 is formed by plating, from the viewpoint of preventing the light shielding layer 38 from being peeled off from the base sheet 37, a base treatment with a chemical solution may be performed.

  The number of base material sheets 37 formed on one sheet material 50 is not limited to 16, and may be increased or decreased according to the size of the sheet material 50 and the size of the target base material sheet 37. A plurality of types of base material sheets 37 may be formed from one sheet material 50. For example, you may form the base material sheet 37 and each base material sheet of the above-mentioned light shielding members 22-24 from the sheet material 50 of 1 sheet.

[Second Embodiment]
A light shielding member 81 shown in FIG. 10 includes a base sheet 82 and a light shielding layer 38. In FIG. 10, the same members as those in the first embodiment are denoted by the same reference numerals as those in FIGS. 2 and 3, and description thereof is omitted. The sheet inner peripheral surface 43 of the base sheet 82 includes a first intersecting surface 43a, a second intersecting surface 43b, and a vertical surface 43c. The first intersecting surface 43 a intersects the thickness direction Z and is connected to the first sheet surface 41. The second intersecting surface 43 b intersects the thickness direction Z and is connected to the second sheet surface 42. The vertical surface 43c is perpendicular to the first sheet surface 41 and the second sheet surface 42, and connects the first intersecting surface 43a and the second intersecting surface 43b.

  The end portion 82e of the base sheet 82 formed by the first intersecting surface 43a, the second intersecting surface 43b, and the vertical surface 43c, and the light shielding layer 38 formed on the end portion 82e are the ends of the light shielding member 81. The thickness of the light shielding layer 38 on the end portion 82e is substantially equal to the thickness of each light shielding layer 38 on the first sheet surface 41 and the second sheet surface 42. Thus, the inner peripheral surface 33 of the light shielding member 81 includes the first surface 33a composed of the light shielding layer 38 on the first intersecting surface 43a, and the second surface 33b composed of the light shielding layer 38 on the second intersecting surface 43b. And a third surface 33c formed of the light shielding layer 38 on the vertical surface 43c. The sheet outer peripheral surface (not shown) of the base sheet 82 is configured in the same manner as the sheet inner peripheral surface 43.

  In the light shielding layer 38 provided on the sheet inner peripheral surface 43 of the present embodiment, the protrusion 46 has a more distal end than the case of the light shielding layer 38 provided on the sheet inner peripheral surface 43 of the first embodiment. Since it is formed in many directions, it can receive and absorb incident light and stray light more reliably. Further, the sheet inner peripheral surface 43 of the present embodiment is a surface perpendicular to the first member surface 31 and the second member surface 32 (surface along the thickness direction) as compared to the sheet inner peripheral surface 43 of the first embodiment. ) Is small, the proportion of light that is specularly reflected with respect to light that is incident on the first member surface 31 and the second member surface 32 in a substantially perpendicular direction is small, and more effectively absorbs incident light and stray light. To do. That is, the light shielding performance is further improved.

  When the light shielding member 81 is viewed from the direction perpendicular to the first sheet surface 41 of the base sheet 82 as shown in FIG. 11, the width WE of the end portion 81e is at least 50% of the thickness T of the light shielding member 81, that is, 50%. The above is preferable. In the present specification, the thickness T of the light shielding member 81 is obtained by observing the cross section of the light shielding member 81 with an optical microscope or the aforementioned SEM. More preferably, the width WE of the end portion 81e is 100% or more of the thickness T. Since the base sheet 82 has the same outer peripheral surface as the inner peripheral surface 43 of the sheet, in FIG. 11, the end portion of the light shielding member 81 on the outer peripheral surface side is also denoted by reference numeral WE indicating the width. It is.

[Third Embodiment]
A light shielding member 91 shown in FIG. 12 includes a base sheet 92 and a light shielding layer 38. In FIG. 12, the same members as those in the first embodiment are denoted by the same reference numerals as those in FIGS. 2 and 3, and the same members as those in the second embodiment are denoted by the same reference numerals as those in FIG. The sheet inner peripheral surface 43 of the base sheet 92 is composed of a first intersecting surface 43a and a second intersecting surface 43b.

  The end portion 92e of the base sheet 92 formed by the first intersecting surface 43a and the second intersecting surface 43b and the light shielding layer 38 formed on the end portion 82e constitute the end portion 91e of the light shielding member 91. The thickness of the light shielding layer 38 on the end 92e is substantially equal to the thickness of each light shielding layer 38 on the first sheet surface 41 and the second sheet surface 42. As described above, the inner peripheral surface 33 of the light shielding member 91 is composed of the first surface 33a composed of the light shielding layer 38 on the first intersecting surface 43a and the second surface 33b composed of the light shielding layer 38 on the second intersecting surface 43b. Composed. The sheet outer peripheral surface (not shown) of the base sheet 92 is configured in the same manner as the sheet inner peripheral surface 43.

  In the light shielding layer 38 provided on the sheet inner peripheral surface 43 of the present embodiment, the protrusion 46 has a more distal end than the case of the light shielding layer 38 provided on the sheet inner peripheral surface 43 of the first embodiment. Since it is formed in many directions, it can receive and absorb incident light and stray light more reliably. Further, since the base sheet 92 does not have the vertical surface 43c unlike the base sheet 82 of the second embodiment, the light shielding layer 38 on the sheet inner peripheral surface 43 of the present embodiment is the first member surface 31 or the second surface. The proportion of light that is specularly reflected with respect to light that enters the member surface 32 in a direction substantially perpendicular to the member surface 32 is small, and incident light and stray light are absorbed more effectively. That is, the light shielding performance is further improved.

  Similarly to the light shielding member 81, the light shielding member 91 has a width WE of the end portion 91 e of the light shielding member 91 when the light shielding member 91 is viewed from the direction perpendicular to the first sheet surface 41 of the base sheet 92. It is preferably at least 50% of the thickness T.

[Fourth Embodiment]
A light shielding member 101 shown in FIG. 13 includes a base sheet 102 and a light shielding layer 38. In FIG. 13, the same members as those in the first embodiment are denoted by the same reference numerals as those in FIGS. 2 and 3, and the same members as those in the second embodiment are denoted by the same reference numerals as those in FIG. The sheet inner peripheral surface 43 of the base sheet 102 is connected to the first sheet surface 41 and is formed as an intersecting surface that intersects the thickness direction Z.

  The end portion 102e of the base sheet 102 formed by the sheet inner peripheral surface 43 and the light shielding layer 38 formed on the end portion 102e constitute an end portion 101e of the light shielding member 101, and are on the end portion 102e. The thickness of the light shielding layer 38 is substantially equal to the thickness of each light shielding layer 38 on the first sheet surface 41 and the second sheet surface 42. Thus, the inner peripheral surface 33 of the light shielding member 101 is formed of the light shielding layer 38 on the sheet inner peripheral surface 43. The sheet outer peripheral surface (not shown) of the base sheet 102 is configured in the same manner as the sheet inner peripheral surface 43.

  In the light shielding layer 38 provided on the sheet inner peripheral surface 43 of the present embodiment, the protrusion 46 has a more distal end than the case of the light shielding layer 38 provided on the sheet inner peripheral surface 43 of the first embodiment. Since it is formed in many directions, it can receive and absorb incident light and stray light more reliably. Further, since the base sheet 92 does not have the vertical surface 43c unlike the base sheet 82 of the second embodiment, the light shielding layer 38 on the sheet inner peripheral surface 43 of the present embodiment is the first member surface 31 or the second surface. The proportion of light that is specularly reflected with respect to light that enters the member surface 32 in a direction substantially perpendicular to the member surface 32 is small, and incident light and stray light are absorbed more effectively. That is, the light shielding performance is further improved.

  Similarly to the light shielding member 81, the light shielding member 101 has a width WE of the end portion 101 e when the light shielding member 101 is viewed from the direction perpendicular to the first sheet surface 41 of the base sheet 102. It is preferably at least 50% of the thickness T.

  The base material sheets 82, 92, 102 of the light shielding members 81, 91, 101 of the second to fourth embodiments are formed by the above-described sheet forming step of performing photoetching. Since the formation method of each base material sheet 82, 92, 102 is basically the same, the details will be described taking the formation method of the base material sheet 82 as an example, and the formation method of the base material sheets 92, 102 is based on the basic method. Only differences from the method of forming the material sheet 82 will be described.

  Specifically, the sheet forming step includes an original mask manufacturing step, a pretreatment step, a photoresist application step, an exposure step, a development step, an etching step, and an etching mask removal step in this order. In the original mask forming step, a pattern original mask used in the exposure step is produced. In the pretreatment step, for example, the surface of the sheet material 50 on which the base sheet 82 is to be formed is degreased and washed to remove deposits such as dirt and oil. By this pretreatment, the photoresist is uniformly applied to the sheet material 50 in the subsequent photoresist applying step, and the adhesion of the photoresist to the sheet material 50 is improved.

  In the photoresist application step, a photoresist is applied to both sheet surfaces of the sheet material 50 that has undergone the pretreatment step. Application | coating is performed by application | coating, for example, The method of application | coating is not specifically limited, For example, there exists a spin coat etc. In the exposure step, the above-described pattern original mask is used to expose the photoresist applied to both sheet surfaces of the sheet material 50, and the pattern shape in the pattern original mask is transferred to the photoresist.

  In the developing step, the photoresist is developed, and an etching mask 104 corresponding to the pattern shape to be formed is formed on the sheet material 50 as shown in FIG. As is well known, there are a positive type and a negative type, and any of them may be used. In this embodiment, a positive type is used. In the etching mask 104, portions excluding the base sheet forming portion 104a and the bridge forming portion 104b are formed as openings 104c. Therefore, in FIG. 14, the sheet material 50 is exposed at the opening 104c. The base sheet forming portion 104a is a mask portion that forms the base sheet 82 (see FIG. 10), and the bridge forming portion 104b is a mask portion that forms a bridge (not shown) that holds each base sheet 82. is there. In this way, the etching mask 104 is formed on each sheet surface of the sheet material 50. In this example, the number of base sheet forming portions 104a formed on the etching mask 104 is 16, but this number is not particularly limited. 14 and 15, the thickness of the etching mask 104 is greatly exaggerated.

  In the etching step, the exposed portion of the sheet material 50 exposed by the opening 104c of the etching mask 104 is removed by etching. In this example, so-called wet etching is performed by etching with an etching solution, but dry etching such as plasma processing may be used. In this embodiment, the etching method is so-called isotropic etching in which etching proceeds in all directions. As shown in FIG. 15, the sheet inner peripheral surface 43 having the first intersecting surface 43a and the second intersecting surface 43b is reliably formed by isotropic etching. And by isotropic etching, the vertical surface 43c is also formed. However, isotropic etching is combined with so-called anisotropic etching in which etching proceeds only in one direction, the vertical surface 43c is formed by anisotropic etching, and the first intersection surface 43a and the second intersection are formed by isotropic etching. The surface 43b may be formed.

  By the etching step, each region of the sheet material 50 exposed at the opening 104 c is removed, and the other regions remain on the sheet material 50. The etching mask removing step is a step of removing the etching mask 104 from the sheet material 50. For removing the etching mask 104, for example, a solution for dissolving the etching mask 104 is brought into contact with the etching mask 104 to dissolve it, and the sheet material 50 is washed and dried. Peeling may be used instead of dissolution. Thus, the sheet material 50 in which the base material sheet 82 and the bridge are formed is obtained in the same manner as the sheet material 50 shown in FIG. The obtained sheet material 50 is subjected to the above-described light shielding layer forming step and separated from the bridge, whereby the light shielding member 81 is obtained.

  The base sheet 92 is formed by strengthening the etching conditions such as the temperature of the etchant, the prescription of the etchant, and the etching time in the above etching step, compared to the etching conditions for forming the base sheet 82. Can do. In addition, the base sheet 92 formed in this manner is subjected to the above-described light shielding layer forming step, and the light shielding layer 38 is formed to have a larger thickness, whereby the light shielding member 81 has a thickness direction such as the third surface 33c. This surface can be formed as a part of the inner peripheral surface 33.

  When forming the base sheet 102, a photoresist is applied to one sheet surface of the sheet material 50 in the photoresist applying step. Then, through an exposure step and a development step, an etching mask 104 is formed only on one sheet surface, and this is subjected to an etching step and an etching mask removal step, whereby the base sheet 102 is obtained.

  In the base sheet 37, 82, 92, 102 of the first to fourth embodiments, the first sheet surface 41, the second sheet surface 42, the sheet inner peripheral surface 43, and the sheet outer peripheral surface are smooth surfaces. However, the equipment sheet is not limited to this. For example, a base sheet having a roughened surface may be used.

[Fifth Embodiment]
A light shielding member 111 shown in FIG. 16 is obtained by replacing the base material sheet 37 of the first embodiment with a base material sheet 112 and includes a light shielding layer 38. The rough outer shape of the base sheet is the same as that of the base sheet 37, but instead of the first sheet surface 41, the second sheet surface 42, the sheet inner peripheral surface 43, and the sheet outer peripheral surface, the first sheet surface 121 A second sheet surface 122, a sheet inner peripheral surface 123, and a sheet outer peripheral surface (not shown) are provided. The same members as those in the first embodiment are denoted by the same reference numerals as those in FIGS.

  The first sheet surface 121, the second sheet surface 122, the sheet inner peripheral surface 123, and the sheet outer peripheral surface (not shown) are rough surfaces on which irregularities are respectively formed. Called. The shapes of the protrusions 116 and the recesses formed between the protrusions 116 are nonuniform. The pitch of the protrusions 116 of the internal concavo-convex structure is larger than the protrusion pitch PS in the surface concavo-convex structure formed by the protrusions 46. That is, PL> PS, where PL is the pitch of the protrusions 116 of the internal concavo-convex structure. Since the pitches of the protrusions 116 are not constant, eleven adjacent protrusions 116 are extracted and the pitch PL is defined as an average value of the pitches between the adjacent protrusions 116 in the same manner as the protrusion pitch PS. As in the case of obtaining the protrusion pitch PS, the pitch between each may be obtained by observing with a SEM.

  The pitch PL is longer than the longest wavelength in the wavelength band of incident light. For example, when the wavelength band of incident light is in the visible light region, the pitch PL is longer than 800 nm when the longest wavelength of visible light is 800 nm. More specifically, the pitch PL is preferably in the micro order of 1 μm (1000 nm) or more.

  The height HL of the protrusion 126 is made larger than the protrusion height HS in the surface uneven structure formed by the protrusion 46. That is, HL> HS. Since the height of the protrusion 116 is not constant, the distance from each bottom surface to the top is obtained for each of the ten adjacent protrusions 116 in the same manner as the protrusion height HS, and the average value of these is calculated. The height is HL. The height of each protrusion 126 may be obtained by observing with a SEM, as in the case of obtaining the protrusion height HS.

  The height HL is ½ or more of the longest wavelength in the wavelength band of incident light. For example, when the wavelength band of incident light is in the visible light region, the height HL of the protrusion 126 is 400 nm or more when the longest wavelength of visible light is 800 nm.

  The internal concavo-convex structure scatters light that cannot be absorbed by the surface concavo-convex structure, thereby enhancing the antireflection effect. Further, since the light shielding layer 38 is formed to have a substantially uniform thickness, a first member surface 131, a second member surface 132, an inner peripheral surface 133, and an outer peripheral surface (not shown) are formed along the internal uneven structure. ing. For this reason, compared with the light shielding layer 38 provided on the base material sheet 37 of the first embodiment, the protrusion 46 is formed with the tip directed in more directions, so that it can receive incident light and stray light more reliably. Absorb. That is, the light shielding performance is further improved. The above-mentioned base material sheets 82, 92, 102 are also preferable because the light shielding performance is further improved by substituting the base material sheet 112 with a roughened surface.

  The base material sheet 112 is obtained by subjecting the base material sheet 37 to an electrolytic surface roughening treatment using an electrolytic solution mainly composed of nitric acid.

(Electrolytic roughening treatment)
The electrolytic surface roughening treatment of the present embodiment is performed using the sheet material 50 on which the base material sheet 37 is formed. As shown in FIG. 17, an electrolytic surface roughening apparatus 151 that performs electrolytic surface roughening treatment includes an electrolytic cell 152, an electrode 153, and an AC power source 154, and the electrolytic cell 152 is an electrolyzer mainly composed of nitric acid. Liquid 156 is stored. In the electrolytic solution 156, the sheet material 50 on which the base sheet 37 is formed and the electrode 153 are arranged to face each other, and each is connected to the AC power source 154. The surface of the base material sheet 37 of the sheet material 50 is subjected to an electrolytic surface roughening treatment by the alternating current supplied by the alternating current power source 154, and the base material sheet 112 is formed from the base material sheet 37. The sheet material 50 that has been subjected to the electrolytic surface roughening treatment is subjected to a light shielding layer forming step as in the first embodiment, and then separated from the bridge 50b (see FIG. 8), whereby the light shielding layer 38 is formed on the base material sheet 112. As a result, the light-shielding member 111 having the structure is obtained.

  Thus, when the roughening treatment is performed, there is an advantage that the adhesion of the light shielding layer 38 can be improved without performing the above-described ground treatment before the plating treatment.

  The electrolytic surface roughening treatment can be performed according to, for example, the electrochemical grain method (electrolytic grain method) described in Japanese Patent Publication No. 48-28123 and British Patent No. 896,563. This electrolytic grain method uses a sinusoidal alternating current, but it may be performed using a special waveform as described in JP-A-52-58602. Further, the waveform described in JP-A-3-79799 can also be used. JP-A-55-158298, JP-A-56-28898, JP-A-52-58602, JP-A-52-152302, JP-A-54-85802, JP-A-60-190392, JP-A-58-120531, JP-A-63-176187, JP-A-1-5889, JP-A-1-280590, JP-A-1-118489, JP-A-1-148592, and JP-A-1-17896. JP-A-1-188315, JP-A-1-1549797, JP-A-2-235794, JP-A-3-260100, JP-A-3-253600, JP-A-4-72079, JP-A-4-72098, The methods described in JP-A-3-267400 and JP-A-1-141094 can also be applied. In addition to the above, it is also possible to perform electrolysis using an alternating current having a special frequency that has been proposed as a method of manufacturing an electrolytic capacitor. For example, it is described in JP-A-58-207400, US Pat. Nos. 4,276,129 and 4,676,879.

  Various proposals have been made for the electrolytic cell 152 and the AC power source 154. U.S. Pat. No. 4,023,637, JP-A-56-123400, JP-A-57-59770, JP-A-53-12738, Japanese Unexamined Patent Publication No. 53-32821, Japanese Unexamined Patent Publication No. 53-32822, Japanese Unexamined Patent Publication No. 53-32823, Japanese Unexamined Patent Publication No. 55-122896, Japanese Unexamined Patent Publication No. 55-132894, Japanese Unexamined Patent Publication No. 62-127500, Japanese Unexamined Patent Publication No. The materials described in JP-A No. -52100, JP-A-1-52098, JP-A-60-67700, JP-A-1-230800, JP-A-3-257199, and the like can be used. Also, JP-A-52-58602, JP-A-52-152302, JP-A-53-12738, JP-A-53-12739, JP-A-53-32821, JP-A-53-32822, JP 53-32833, JP 53-32824, JP 53-32825, JP 54-85802, JP 55-122896, JP 55-13284, JP 48-28123, JP-B-51-7081, JP-A-52-13338, JP-A-52-133840, JP-A-52-133844, JP-A-52-133845, JP-A-53- Nos. 149135 and 54-146234 can be used.

  The electrolytic solution 156 is an aqueous solution mainly composed of nitric acid, and the concentration of nitric acid is preferably 0.5 to 2.5% by mass. However, in consideration of use in the smut removal treatment described later, 0.7 to It is particularly preferably 2.0% by mass. Moreover, it is preferable that liquid temperature is 20-80 degreeC, and it is more preferable that it is 30-60 degreeC.

  An aqueous solution mainly composed of nitric acid has a nitric acid compound having nitrate ions such as aluminum nitrate, sodium nitrate, ammonium nitrate, or hydrochloric acid ions such as aluminum chloride, sodium chloride, ammonium chloride in an aqueous solution of nitric acid having a concentration of 1 to 100 g / L. At least one of the hydrochloric acid compounds can be added and used in a range from 1 g / L to saturation. Moreover, the metal contained in aluminum alloys, such as iron, copper, manganese, nickel, titanium, magnesium, a silica, may melt | dissolve in the aqueous solution which has nitric acid as a main component. Preferably, it is preferable to use a solution obtained by adding aluminum chloride, aluminum nitrate or the like to an aqueous solution of nitric acid having a concentration of 0.5 to 2% by mass so that the aluminum ion is 3 to 50 g / L.

  Further, by adding and using a compound capable of forming a complex with Cu, uniform graining is possible even for an aluminum base sheet 22 containing a large amount of Cu. Examples of the compound capable of forming a complex with Cu include ammonia; hydrogen atom of ammonia such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, cyclohexylamine, triethanolamine, triisopropanolamine, EDTA (ethylenediaminetetraacetic acid), etc. And amines obtained by substituting with a hydrocarbon group (aliphatic, aromatic, etc.); metal carbonates such as sodium carbonate, potassium carbonate, potassium hydrogen carbonate and the like. In addition, ammonium salts such as ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, and ammonium carbonate are also included. The temperature is preferably 10-60 ° C, more preferably 20-50 ° C.

  The AC power supply wave used for the electrolytic surface roughening treatment is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave or the like is used, but a rectangular wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable. In the trapezoidal wave, the time (TP) until the current reaches a peak from zero is preferably 1 to 3 msec. If it is less than 1 msec, processing irregularities such as chatter marks that occur perpendicular to the traveling direction of the base sheet 22 are likely to occur. If the TP exceeds 3 msec, when using a nitric acid electrolyte, it will be susceptible to trace components in the electrolyte typified by ammonium ions, etc. that spontaneously increase due to the electrolytic treatment, and uniform graining will be performed. It becomes difficult.

  A trapezoidal wave alternating current duty ratio of 1: 2 to 2: 1 can be used. However, as described in Japanese Patent Laid-Open No. 5-195300, in an indirect power feeding method in which no conductor roll is used for aluminum. A duty ratio of 1: 1 is preferable. A trapezoidal AC frequency of 0.1 to 120 Hz can be used, but 50 to 70 Hz is preferable in terms of equipment. If it is lower than 50 Hz, the carbon electrode 153 is likely to be dissolved, and if it is higher than 70 Hz, it is easily affected by an inductance component on the power supply circuit, and the power supply cost is increased.

  As the electrolytic cell 152, an electrolytic cell used for a known surface treatment such as a vertical type, a flat type, and a radial type can be used, but a radial type electrolytic cell as described in JP-A-5-195300 is particularly preferable. preferable.

By an electrolytic surface roughening treatment using an electrolytic solution mainly composed of nitric acid, an internal concavo-convex structure having a protrusion pitch PH of more than 0.5 μm and not more than 5 μm can be formed. However, when the amount of electricity is relatively large, the electrolytic reaction is concentrated, and an internal concavo-convex structure in which the protrusion pitch PH exceeds 5 μm can be formed. In order to obtain such a surface shape, the total amount of electricity involved in the anode reaction of the substrate sheet 112 at the time when the electrolytic reaction is completed is preferably 1 to 1000 C / dm ² , and preferably 50 to 300 C / more preferably in the range of dm ^2. The current density at this time is preferably ²⁰ to 100 A / dm ² .

  The step of forming the internal concavo-convex structure may be combined with the following surface treatment in an electrolytic surface roughening treatment as an electrochemical surface treatment using an electrolytic solution mainly composed of nitric acid. As a representative combined method, for example, there is a method in which the base sheet 37 is subjected to a mechanical surface roughening treatment, an alkali etching treatment, a desmutting treatment with an acid, and the electrolytic surface roughening treatment. In this method, after the electrolytic surface roughening treatment, an alkali etching treatment and an acid desmut treatment may be further performed.

(Mechanical roughening treatment)
For example, a brush grain method is used as a method for performing the mechanical surface roughening treatment. In addition, by using electric discharge machining, shot blasting, laser, plasma etching, etc., a method of performing repetitive transfer using a transfer roll etched with fine irregularities, or a surface with irregularities coated with fine particles on a substrate sheet It is also possible to use a method in which the surface is brought into contact with the surface 37 and a pressure is repeatedly applied several times thereon, and a concavo-convex pattern corresponding to the average diameter of the fine particles is repeatedly transferred onto the substrate sheet 22 a plurality of times. As a method for imparting fine irregularities to the transfer roll, known methods described in JP-A-3-8635, JP-A-3-66404, JP-A-63-65017, etc. may be used. it can. Further, a fine groove may be cut in two directions using a die, a cutting tool, a laser, or the like on the roll surface, and a square unevenness may be formed on the surface. The roll surface may be subjected to a known etching process or the like so that the formed square irregularities are rounded. Further, in order to increase the surface hardness, quenching, hard chrome plating, or the like may be performed. In addition, as the mechanical surface roughening treatment, methods described in JP-A Nos. 61-162351 and 63-104889 can be used. In the present invention, the above-described methods can be used in combination in consideration of productivity and the like. These mechanical surface roughening treatments are preferably performed before the electrolytic surface roughening treatment.

Hereinafter, the brush grain method used suitably as a mechanical roughening process is demonstrated. The brush grain method generally uses a roller-like brush in which a large number of brushes such as synthetic resin bristles made of synthetic resin such as nylon, propylene, and vinyl chloride resin are planted on the surface of a cylindrical body. This is performed by rubbing one or both of the surfaces of the substrate sheet 22 while spraying a slurry liquid containing an abrasive on the brush. Instead of the roller brush and the slurry liquid, a polishing roller which is a roller having a polishing layer on the surface can be used. When a roller brush is used, the flexural modulus is preferably 10,000 to 40,000 kg / cm ² , more preferably 15,000 to 35,000 kg / cm ² , and the bristle strength is preferably Brush hair that is 500 g or less, more preferably 400 g or less is used. The diameter of the brush bristles is generally 0.2 to 0.9 mm. The length of the brush bristles can be appropriately determined according to the outer diameter of the roller brush and the diameter of the body, but is generally 10 to 100 mm.

  A well-known thing can be used for an abrasive | polishing agent. For example, abrasives such as pumicestone, silica sand, aluminum hydroxide, alumina powder, silicon carbide, silicon nitride, volcanic ash, carborundum, and gold sand; a mixture thereof can be used. Of these, pumiston and silica sand are preferable. In particular, silica sand is preferable in terms of excellent surface roughening efficiency because it is harder and less likely to break than Pamiston. The average particle diameter of the abrasive is preferably 3 to 50 μm, and more preferably 6 to 45 μm in terms of excellent surface roughening efficiency and a narrow graining pitch. For example, the abrasive is suspended in water and used as a slurry. In addition to the abrasive, the slurry liquid may contain a thickener, a dispersant (for example, a surfactant), a preservative, and the like. The specific gravity of the slurry liquid is preferably 0.5-2.

  As an apparatus suitable for the mechanical surface roughening treatment, for example, an apparatus described in Japanese Patent Publication No. 50-40047 can be given.

(Alkaline etching treatment)
The alkali etching treatment is a treatment for dissolving the surface layer by bringing the base sheet 37 into contact with an alkaline solution. The alkali etching process performed before the electrolytic surface roughening process is performed for the purpose of removing rolling oil, dirt, natural oxide film, and the like on the surface of the base sheet 37.

Etching amount of the alkali etching treatment is preferably 0.05 to 10 g / ^{m 2,} and more preferably 1 to 5 g / ^{m 2.} If the etching amount is less than 0.05 g / m ² , rolling oil, dirt, natural oxide film, etc. may remain on the surface, so that a uniform wave structure cannot be generated in the subsequent electrolytic surface roughening treatment. May occur. On the other hand, when the etching amount is 1 to 10 g / m ² , the surface rolling oil, dirt, natural oxide film, and the like are sufficiently removed. An etching amount exceeding the above range is economically disadvantageous.

The alkaline etching treatment performed immediately after the electrolytic surface roughening treatment is performed for the purpose of dissolving the smut generated in the acidic electrolyte and dissolving the edge portion of the wave structure formed by the electrolytic surface roughening treatment. Is called. Since the wave structure formed by the electrolytic surface roughening treatment differs depending on the type of the electrolytic solution, the optimum etching amount also varies. However, the etching amount of the alkali etching treatment performed after the electrolytic surface roughening treatment is 0.1 to 5 g / m ² is preferred. When a nitric acid electrolyte is used, the etching amount needs to be set larger than when a hydrochloric acid electrolyte is used. When the electrolytic surface roughening treatment is performed a plurality of times, an alkali etching treatment can be performed as necessary after each treatment.

  Examples of the alkali used in the alkaline solution include caustic alkali and alkali metal salts. Specifically, examples of caustic alkali include caustic soda and caustic potash. Examples of alkali metal salts include alkali metal silicates such as sodium silicate, sodium silicate, potassium metasilicate, and potassium silicate; alkali metal carbonates such as sodium carbonate and potassium carbonate; sodium aluminate and alumina. Alkali metal aluminates such as potassium acid; alkali metal aldones such as sodium gluconate and potassium gluconate; dibasic sodium phosphate, dibasic potassium phosphate, tribasic sodium phosphate, tertiary potassium phosphate, etc. An alkali metal hydrogen phosphate is mentioned. Among these, a caustic alkali solution and a solution containing both a caustic alkali and an alkali metal aluminate are preferable from the viewpoint of high etching rate and low cost. In particular, an aqueous solution of caustic soda is preferable.

  Although the density | concentration of an alkaline solution can be determined according to the etching amount, it is preferable that it is 1-50 mass%, and it is more preferable that it is 10-35 mass%. When aluminum ions are dissolved in the alkaline solution, the concentration of aluminum ions is preferably 0.01 to 10% by mass, and more preferably 3 to 8% by mass. The temperature of the alkaline solution is preferably 20 to 90 ° C. The treatment time is preferably 1 to 120 seconds.

  As a method for bringing the base sheet 37 into contact with the alkaline solution, for example, a method in which the base sheet 37 is passed through a tank containing the alkaline solution, the base sheet 37 is immersed in a tank containing the alkaline solution. And a method of spraying an alkaline solution onto the surface of the base sheet 37.

(Desmut treatment)
After the electrolytic surface roughening treatment or the alkali etching treatment, pickling (desmut treatment) is preferably performed in order to remove dirt (smut) remaining on the surface. Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid. In the desmutting treatment, for example, the base sheet 37 is brought into contact with an acidic solution (containing 0.01 to 5% by mass of aluminum ions) having a concentration of 0.5 to 30% by mass such as hydrochloric acid, nitric acid, and sulfuric acid. To do. As a method of bringing the base sheet 37 into contact with the acidic solution, for example, the base sheet 37 is passed through a tank containing the acidic solution, and the base sheet 37 is placed in a tank containing the acidic solution. Examples include a dipping method and a method in which an acidic solution is sprayed on the surface of the base sheet 37. In the desmut treatment, the waste solution of the electrolyte solution 156 mainly composed of nitric acid discharged in the above-described electrolytic surface roughening treatment can be used as the acidic solution. It is preferable that the liquid temperature of a desmut process is 25-90 degreeC. Moreover, it is preferable that processing time is 1-180 second. Aluminum and aluminum alloy components may be dissolved in the acidic solution used for the desmut treatment.

  In the above, as the step of forming the internal uneven structure, the electrolytic surface roughening process using an electrolytic solution mainly composed of nitric acid, or the combination of the electrolytic surface roughening process and the mechanical surface roughening process has been described as an example. The step of forming the internal concavo-convex structure may be performed only by mechanical surface roughening without performing electrolytic surface roughening. However, since the mechanical roughening process generates dust, a process for removing the dust is required. Therefore, when it is desired to eliminate the dust removal process and improve the production efficiency, it is preferable to perform the electrolytic surface roughening process mainly without performing the mechanical surface roughening process.

  The light shielding members 21, 81, 91, 101, and 111 of the above embodiments all have a multilayer structure including the base material sheets 37, 82, 92, 102, and 112 and the light shielding layer 38. The light shielding member of the present invention is not limited to such a multilayer structure, and may be a single layer structure.

21, 81, 91, 101, 111 Light-shielding member 37, 82, 92, 102, 112 Base sheet 38 Light-shielding layer 41, 42 First, second sheet surface 43 Sheet inner peripheral surface 43a, 43b First, second intersection surface

Claims (6)

In a light shielding member having a plurality of cone-shaped protrusions arranged at a pitch equal to or less than the wavelength of incident light,
The light-shielding member, wherein the plurality of protrusions are formed with nonuniformly oriented tips. A base sheet;
A light shielding layer provided on the surface of the base sheet and having the plurality of protrusions;
The light shielding member according to claim 1.   The light shielding member according to claim 2 or 3, wherein an end surface of the base sheet has an intersecting surface that intersects a thickness direction of the base sheet.   The light shielding member according to claim 3, wherein a width of an end portion of the light shielding member formed from the end surface is at least 50% of a thickness of the light shielding member when viewed from a direction perpendicular to a sheet surface of the base sheet. In the manufacturing method of the light shielding member comprising a plurality of cone-shaped protrusions arranged at a pitch equal to or less than the wavelength of the incident light,
A sheet forming step of forming a base sheet from the sheet material;
A light shielding layer forming step of forming a light shielding layer having the plurality of protrusions on the surface of the base sheet;
Have
In the light shielding layer forming step, a plurality of protrusions whose tip directions are not uniform are formed by plating on the surface of the base sheet.   6. The method for manufacturing a light shielding member according to claim 5, wherein the sheet forming step forms an intersecting surface intersecting a thickness direction of the base sheet as at least a part of an end surface of the base sheet by photoetching the sheet material. .

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