Method for producing metal product and metal product

Abstract

To provide a method for producing a metal product having high definition and suppressed deformation failure.SOLUTION: The method for producing a metal product includes: preparing a metal foil having a first surface and a second surface opposite to the first surface; forming a first etching mask (EM) having a first through hole on the first surface; supplying a first etching liquid to the first surface provided with the first EM to form a first recess in the first surface at the position of the first through hole, and removing the first EM from the first surface; bonding a protective layer made of a first dry film resist (DFR) to the first surface and adhering the protective layer to the inner wall of the first recess; bonding a second DFR to the second surface; forming a second through hole in the second DFR at the position of the first recess; obtaining a second EM and supplying a second etching liquid to the second surface provided with the second EM; forming a second recess in the second surface at the position of the second through hole so that the first recess and the second recess are connected at their bottoms to form a third through hole; and simultaneously removing the protective layer and the second EM from the metal foil provided with the third through hole.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a metal product and a metal product. [Background technology]

[0002] In recent years, with the rapid miniaturization and high performance of electronic devices, there has been an increasing demand for high-precision metal products used in their manufacture. A specific example of such a metal product is a deposition mask. In the manufacturing process of organic electroluminescence (EL) display devices, a vacuum deposition method is used to form organic EL elements. In the vacuum deposition method, a deposition mask containing through-holes arranged in a desired pattern is used, allowing for the selective formation of thin films of organic EL elements in desired regions of the organic EL display device.

[0003] Furthermore, the use of deposition masks is expected to enable miniaturization and increased capacitance in the manufacturing process of multilayer ceramic capacitors. Multilayer ceramic capacitors are formed by stacking a predetermined number of laminates of ceramic dielectric layers and internal electrode layers, with the ceramic dielectric layers and internal electrode layers alternately arranged. By thinning the ceramic dielectric layers and stacking more of them, the capacitance per volume can be increased, enabling miniaturization. In the typical manufacturing process of multilayer ceramic capacitors, the internal electrode layers are formed on the ceramic dielectric layers by screen-printing a conductive paste containing nickel or other materials. However, screen printing has been problematic in that it is difficult to thin the internal electrode layers due to the particle size of the paste. Therefore, in recent years, deposition methods have attracted attention as an alternative to screen printing, and deposition masks have been considered as metal masks for use in deposition.

[0004] Here, the deposition mask is usually a metal etching product obtained by wet etching (photo-etching method) using photolithography technology. In manufacturing a deposition mask by this photo-etching method, a corrosion-resistant photoresist film is formed in a desired pattern on the surface of a metal plate, and the metal parts exposed from the pattern are corroded with an etching solution to form through-holes (see, for example, Non-Patent Document 1).

[0005] High-resolution metal products such as deposition masks directly lead to the miniaturization and high performance of electronic devices such as organic electroluminescence (EL) displays and multilayer ceramic capacitors. This has led to a growing demand for high-resolution metal products used in the manufacture of these electronic devices, and even higher resolution is expected. However, when manufacturing metal products using photoetching, wet etching using an etching solution is generally isotropic, making it difficult to form through-holes with a high aspect ratio, where the opening width is narrower than the thickness of the metal plate.

[0006] Two-stage etching is a method to solve this problem. In two-stage etching, a resist pattern is formed on both sides of a metal plate, and one side is half-etched to a predetermined depth. After that, a liquid resin composition containing a photosensitive resin or the like is temporarily filled into the half-etched portion (recess) as a backcoat material, and this is solidified to form a protective layer. Then, etching is performed from the other side to form a through-hole (see, for example, Non-Patent Document 1). After the through-hole is formed, the resist pattern and the protective layer made of the backcoat material are simultaneously removed using a stripper such as an alkaline solution. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] "Fundamentals and Applications of Wet Etching" by Kato, Homonori, Journal Free, 1998, Vol. 49, No. 10, pp. 1031-1037<URL:https: / / www.jstage.jst.go.jp / article / sfj1989 / 49 / 10 / 49_10_1031 / _pdf / -cHar / ja> Summary of the Invention [Problem to be solved by the invention]

[0008] The two-stage etching method described above allows the formation of through-holes with a high aspect ratio, with opening widths narrower than the thickness of the metal plate, making it possible to obtain high-definition etched metal products. However, when the resist pattern and the protective layer made of the backcoat material are simultaneously removed using a stripper after the through-hole formation, stress (warping) occurs in the processed metal plate due to differences in stripping properties (stripping speeds) for each stripper, resulting in a problem of deformation defects.

[0009] An object of the present invention is to provide a technique for manufacturing a metal product having highly precise through holes and suppressing the occurrence of deformation defects. [Means for solving the problem]

[0010] According to one aspect of the present invention, a method for manufacturing a metal foil includes preparing a metal foil having a first surface and a second surface opposite to the first surface, forming a first etching mask having a first through hole on the first surface, supplying a first etching liquid to the first surface on which the first etching mask is provided to form a first recess in the first surface at the position of the first through hole, removing the first etching mask from the first surface, bonding a protective layer made of a first dry film resist to the first surface and adhering the protective layer to an inner wall of the first recess, and bonding a second dry film resist to the first surface. a second etching mask; supplying a second etching liquid to the second surface on which the second etching mask is provided to form a second recess in the second surface at the position of the second through hole, so that the first recess and the second recess are connected at their bottoms to form a third through hole; and simultaneously removing the protective layer and the second etching mask from the metal foil in which the third through hole is provided.

[0011] According to another aspect of the present invention, there is provided a method for manufacturing a metal product according to the above aspect, in which the protective layer and the second etching mask are simultaneously removed from the metal foil using an alkaline solution as a stripping solution.

[0012] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to any one of the above aspects, wherein the first dry film resist and the second dry film resist have the same composition and thickness.

[0013] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to any of the above aspects, wherein the metal foil has a thickness in the range of 15 to 50 μm.

[0014] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to any of the above aspects, further comprising performing a first roughening treatment to roughen the inner wall of the first recess prior to removing the first etching mask from the first surface.

[0015] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to the above aspect, wherein the first roughening treatment is carried out so that the roughened inner wall of the first recess has an arithmetic mean roughness Sa in the range of 0.30 to 0.70 μm.

[0016] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to any of the above aspects, further comprising performing a second roughening treatment to roughen the inner wall of the second recess prior to removing the protective layer and the second etching mask from the metal foil.

[0017] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to the above aspect, wherein the second roughening treatment is carried out so that the roughened inner wall of the second recess has an arithmetic mean roughness Sa in the range of 0.30 to 0.70 μm.

[0018] According to yet another aspect of the present invention, there is provided a method for manufacturing a metal product according to any of the above aspects, wherein the first recess and the second recess are formed such that the second recess has a greater depth than the first recess.

[0019] According to yet another aspect of the present invention, there is provided a method for producing a metal product according to any one of the above aspects, in which a deposition mask is obtained as the metal product.

[0020] According to yet another aspect of the present invention, there is provided a metal product having a first surface and a second surface opposite to the first surface, wherein a first recess tapering toward the second surface is provided on the first surface, and a second recess tapering toward the first surface is provided on the second surface, the first recess and the second recess being connected at their bottoms to form a through hole, and the inner wall of the first recess has an arithmetic mean roughness Sa in the range of 0.30 to 0.70 μm.

[0021] According to yet another aspect of the present invention, there is provided a metal product according to the above aspect, wherein the inner wall of the second recess has an arithmetic mean roughness Sa within a range of 0.30 to 0.70 μm.

[0022] According to yet another aspect of the present invention, there is provided a metal product according to any one of the above aspects, wherein the second recess has a greater depth than the first recess.

[0023] According to yet another aspect of the present invention, there is provided a metal product according to any of the above aspects, having a thickness in the range of 15 to 50 μm.

[0024] According to yet another aspect of the present invention, there is provided a metal product according to any of the above aspects, which is a deposition mask. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a technique for manufacturing a metal product having highly precise through holes and suppressing the occurrence of deformation defects. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view showing a part of a metal product obtained by a method for manufacturing a metal product according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged cross-sectional view of the metal product shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing one step of the method for manufacturing a metal product according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing another step of the method for manufacturing a metal product according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view showing still another step of the method for manufacturing a metal product according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing still another step of the method for manufacturing a metal product according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing still another step of the method for manufacturing a metal product according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view showing still another step of the method for manufacturing a metal product according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. The following items can be incorporated into each of the above aspects, either singly or in combination.

[0028] Furthermore, the embodiments shown below are merely examples of configurations for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited by the materials, shapes, structures, etc. of the components described below. Various modifications can be made to the technical idea of ​​the present invention within the technical scope defined by the claims.

[0029] In the drawings, elements having the same or similar functions are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, the drawings are schematic, and the relationship between dimensions in one direction and dimensions in another direction, and the relationship between the dimensions of one member and the dimensions of another member, etc. may differ from the actual relationship.

[0030] Fig. 1 is a cross-sectional view parallel to the thickness direction showing a part of a metal product obtained by the manufacturing method for a metal product according to the first embodiment of the present invention. Fig. 2 is a cross-sectional view showing a part of the metal product shown in Fig. 1 in an enlarged scale. Figs. 3 to 8 are process diagrams for explaining the manufacturing method for a metal product according to the first embodiment. The metal product obtained by the manufacturing method according to the first embodiment can be used, for example, in applications requiring high-definition patterns, such as deposition masks.

[0031] The metal product 1 shown in FIGS. 1 and 2 has a first surface 11a and a second surface 11b opposite thereto. The metal foil 11 includes a first recess 111 tapered toward the second surface 11b provided on the first surface 11a, and a second recess 211 tapered toward the first surface 11a provided on the second surface 11b. In the metal product 1, the first recess 111 and the second recess 211 are connected at their bottoms, i.e., at a constricted portion 311, and together form a third through hole. As will be described in detail later, from the perspective of dimensional accuracy of the third through hole, the second recess 211 is preferably larger than the first recess 111. That is, the depth H2 of the second recess 211 is preferably larger than the depth H1 of the first recess 111. Furthermore, the opening diameter W2 of the second recess 211 is preferably larger than the opening diameter W1 of the first recess 111. The opening diameter W3 of the constricted portion 31 tends to be smaller than the opening diameter W1 of the first recess 111, but it is preferable that this difference be small, and it is more preferable that the opening diameter W3 of the constricted portion 31 be equal to the opening diameter W1 of the first recess 111. Here, the opening diameter W3 of the constricted portion 31 refers to the dimension of the third through hole.

[0032] The metal product 1 is an etched metal product obtained by the manufacturing method according to the first embodiment described below. This manufacturing method according to the first embodiment enables the formation of highly precise through holes by two-stage etching, while suppressing the occurrence of deformation defects in the processed metal plate, which is a problem with two-stage etching.

[0033] That is, the manufacturing method according to the first embodiment includes the steps of preparing a metal foil 11 having a first surface 11a and a second surface 11b that is the back surface of the first surface, forming a first etching mask having a first through hole on the first surface, supplying a first etching liquid to the first surface on which the first etching mask is provided to form a first recess in the first surface at the position of the first through hole, performing a first roughening treatment to roughen the inner wall of the first recess, removing the first etching mask from the first surface, and bonding a protective layer made of a first dry film resist to the first surface and adhering the protective layer to the inner wall of the first recess. laminating a second dry film resist to the second surface, forming second through holes in the second dry film resist at the positions of the first recesses to obtain a second etching mask, supplying a second etching solution to the second surface on which the second etching mask is provided to form second recesses in the second surface at the positions of the second through holes so that the first recess and the second recess are connected at their bottoms to form third through holes, performing a second roughening treatment to roughen the inner walls of the second recesses, and simultaneously removing the protective layer and the second etching mask from the metal foil on which the third through holes are provided. Of the above steps, the first roughening treatment and the second roughening treatment can be omitted. Each step will be described in detail below.

[0034] <Preparing the metal foil> The material of the metal foil 11 constituting the metal product 1 may be any etchable metal, such as iron, copper, or an alloy thereof. Examples of iron alloys include iron-nickel alloys, iron-nickel-cobalt alloys, and iron-chromium-nickel alloys. The iron-nickel alloy may be, for example, an iron alloy containing 34% to 38% by mass of nickel, i.e., an Invar material. The iron-nickel-cobalt alloy may be, for example, an iron alloy containing 30% to 34% by mass of nickel and cobalt, i.e., a Super Invar material. The iron-chromium-nickel alloy may be chromium-nickel stainless steel, such as SUS304 or SUS430. The iron-chromium-nickel alloy has a larger thermal expansion coefficient than the iron-nickel alloy and the iron-nickel-cobalt alloy. Therefore, when the metal product 1 is used as a deposition mask, if the degree of temperature rise of the deposition mask during deposition is small, an iron-chromium-nickel alloy can be suitably used, and if the degree of temperature rise of the deposition mask is large, an iron-nickel alloy or an iron-nickel-cobalt alloy can be suitably used.

[0035] The thickness T1 of the metal foil 11 is not particularly limited and is set appropriately depending on the application. For example, the thickness T1 of the metal foil 11 is preferably 50 μm or less, more preferably in the range of 5 to 50 μm, and even more preferably in the range of 15 to 50 μm. As the thickness T1 of the metal foil 11 becomes thinner, the strength of the metal foil 11 decreases, and deformation defects tend to become more likely to occur.

[0036] A long metal foil is usually used as the metal foil 11. The long metal foil 11 is conveyed on a conveying means such as a conveying roller, while the steps described in detail below are continuously carried out. In one example, after the series of steps are completed, the metal foil 11 having the third through holes formed therein is cut into sheet-like metal products 1. Furthermore, the metal foil 11 is usually used after cleaning the surface to remove the oxide coating layer.

[0037] <Formation of first etching mask> 3 shows a process diagram in which a first etching mask 21 having a plurality of first through holes 22 is formed on the first surface 11a of the metal foil 11. The first etching mask 21 can be formed by a photolithography process described below.

[0038] Here, first, a resist layer is formed on the first surface 11a of the metal foil 11 using a negative photoresist. The structure with the resist layer formed on the first surface 11a is not shown. In order to accurately fabricate the first etching mask 21 with a narrow opening width, the resist layer is required to have excellent film thickness uniformity and high resolution. Therefore, it is preferable to use a dry film resist as the resist layer.

[0039] The dry film resist may be a dry film resist including a base film made of polyethylene terephthalate (PET) or the like and a photosensitive layer laminated on the base film and having photosensitivity. For example, a dry film resist including a photosensitive material such as an acrylic photocurable resin, an epoxy photocurable resin, a polyimide photocurable resin, or a styrene photocurable resin may be used. Among these, a dry film resist including an acrylic photocurable resin (acrylic dry film resist) is preferred. An example of such an acrylic dry film resist is Dry Film Resist RY3310 manufactured by Resonac Corporation.

[0040] When a dry film resist is used as the resist layer, lamination can be performed by using a laminator to attach the dry film resist onto the first surface 11a of the metal foil 11. The thickness of the dry film resist may be, for example, in the range of 10 to 70 μm.

[0041] The resist layer may be formed by applying a liquid photoresist. When applying the liquid photoresist, a commonly used photoresist coating method such as a spin coater, a roll coater, or a dip coater can be used. After applying the liquid photoresist, it is preferable to dry it.

[0042] Next, an exposure mask that does not transmit light to the region of the resist layer that is to be removed is prepared and placed on the resist layer. Note that the structure in which the exposure mask is placed on the resist layer is not shown. The exposure mask is then sufficiently adhered to the resist layer by vacuum contact, and exposure is performed. Note that a positive photoresist may also be used. In this case, an exposure mask that allows light to transmit to the region of the resist layer that is to be removed is used.

[0043] Next, the exposed resist layer is developed to obtain a first etching mask 21 having a plurality of first through holes 22 as shown in FIG. 3. Development can be performed by immersing in an alkaline developer or by spraying an alkaline developer; for example, shower development, spray development, dip (immersion) development, puddle development, etc. can be used. As the alkaline developer, an aqueous solution of sodium carbonate, sodium hydroxide, etc. can be used. An antifoaming agent or a surfactant may also be added to the developer. In addition, in order to more firmly adhere the first etching mask 21 to the metal foil 11, a heat treatment step of heating the first etching mask 21 may be performed after the development step.

[0044] <First surface etching process> FIG. 4 shows a process diagram in which the first recess 111 is formed on the first surface 11a at the position of the first through hole 22 by etching the first surface 11a of the metal foil 11 provided with the first etching mask 21 (first surface etching).

[0045] This first surface etching is performed by wet etching. That is, by supplying a first etching liquid to the first surface 11a on which the first etching mask 21 is provided, the first etching liquid erodes the first surface 11a at the positions of the first through-holes 22 that are not covered by the first etching mask 21. The supply of the first etching liquid to the first surface 11a is performed by, for example, spray etching. In spray etching, the first etching liquid is sprayed toward the first surface 11a through the first etching mask 21 from a nozzle arranged on the side of the metal foil 11 that faces the first surface 11a as it is being transported. As a result, a plurality of first recesses 111 are formed in the first surface 11a at the positions of the first through-holes 22.

[0046] The first etching solution may be an acidic etching solution that can etch the metal foil 11 made of a material such as SUS, Invar, etc. The acidic etching solution may be, for example, a solution obtained by mixing a ferric chloride solution, a ferric perchlorate solution, or a mixed solution of a ferric perchlorate solution and a ferric chloride solution with any of perchloric acid, hydrochloric acid, sulfuric acid, formic acid, and acetic acid.

[0047] Thereafter, the first etching mask 21 is removed to obtain the metal foil 11 shown in FIG. 5. However, as described below, prior to removing the first etching mask 21, it is preferable to perform a first roughening treatment to roughen the inner wall 111a of the first recess.

[0048] <First roughening treatment> In the manufacturing method according to the first embodiment, after the first surface etching step, it is preferable to perform a first roughening treatment to roughen the inner wall 111a of the first recess before removing the first etching mask 21. As shown in Fig. 6, the first roughening treatment is closely related to covering the first surface 11a with a protective layer 30 made of a first dry film in a subsequent step.

[0049] That is, in the manufacturing method according to the first embodiment, the first surface 11a is coated with a protective layer 30 as shown in FIG. 6 in preparation for the second-surface etching process described below. This prevents the second etching solution from reaching the inner wall 111a of the first recess and eroding the inner wall 111a during the second-surface etching process. For reasons described below, the manufacturing method according to the first embodiment uses a first dry film resist as the protective layer 30. In conventional two-stage etching, a liquid photosensitive resin composition is used as the protective layer, rather than a first dry film resist, and the protective layer is formed by curing the coating. When a first dry film resist is used as the protective layer 30, adhesion is inferior compared to when a cured coating of this conventional liquid photosensitive resin composition is used. For this reason, it is preferable to roughen the inner wall 111a of the first recess and improve adhesion between the protective layer 30 and the inner wall 111a of the first surface by using an anchor effect.

[0050] Although the adhesion to the metal foil 11 can be improved by heating the protective layer 30 made of the first dry film resist, the heating temperature may become too high to obtain the desired adhesion by this alone, which may result in a disadvantage of a longer peeling time due to a deterioration in the alkali solubility of the protective layer 30.

[0051] The first roughening treatment of the surface of the inner wall 111a of the first recess can be performed, for example, by chemical etching using a microetching agent. The microetching agent used here refers to an etching agent that, when brought into contact with a metal surface, slightly etches the metal surface, forming fine irregularities (microetching) on ​​the metal surface. Known chemicals capable of imparting the desired surface roughness to the inner wall 111a of the first recess can be used as the microetching agent. Examples of microetching agents include organic acid-based microetching agents containing organic acids such as formic acid and acetic acid, and inorganic acid-based microetching agents containing inorganic acids such as hydrochloric acid and sulfuric acid. In addition to the organic acid and / or inorganic acid, these microetching agents may further contain metal compounds such as iron chloride, oxidizing agents, halogens, polymers, ammonium salts, amines, surfactants, etc., for the purpose of adjusting the roughened shape and etching rate.

[0052] The first roughening treatment is performed so that the inner wall 111a of the first recess after the roughening treatment has an arithmetic mean roughness Sa preferably in the range of 0.15 to 0.70 μm, more preferably in the range of 0.30 to 0.70 μm. If the arithmetic mean roughness Sa of the inner wall 111a is too low, the intended effect of improving adhesion cannot be achieved, which may cause a decrease in the accuracy of the dimension of the third through hole (the opening diameter W3 of the constricted portion 31). Furthermore, if the arithmetic mean roughness Sa of the inner wall 111a is too high, the first dry film resist cannot conform to the inner wall 111a of the first recess, making voids more likely to occur. This also reduces adhesion and may cause a decrease in the dimensional accuracy of the third through hole. The first roughening treatment controls the surface roughness of the inner wall 111a of the first recess within an appropriate range, thereby improving adhesion and preventing the second etching solution from seeping into the inner wall 111a of the first recess during second surface etching, thereby enabling the formation of a metal product 1 having a highly precise third through hole with excellent dimensional accuracy.

[0053] Here, the arithmetic mean roughness Sa can be measured according to the method specified in ISO25178 using a three-dimensional white light interference microscope, a scanning electron microscope, an electron beam three-dimensional roughness analyzer, or the like.

[0054] The first roughening treatment using a microetching agent is performed by, for example, spray etching. In spray etching, a microetching agent is sprayed onto the first surface 11a through the first etching mask 21 from a nozzle disposed on the side facing the first surface 11a of the transported metal foil 11. The first roughening treatment by spray etching is performed by appropriately adjusting the etching time, spray pressure, concentration, temperature, etc. of the chemical etching agent to achieve the above-mentioned surface roughness.

[0055] <Removal of the first etching mask> Next, the first etching mask 21 is removed from the first surface 11a. FIG. 5 is a process diagram showing the state after the first etching mask 21 has been removed. The first etching mask 21 is removed using, for example, an alkaline stripper. In this case, a heated alkaline stripper can be used. Alternatively, a stripper containing a strong alkaline substance such as tetraalkylammonium hydroxide can be used.

[0056] <Laminating the protective layer> 6 is a process diagram showing a state in which the protective layer 30 is bonded to the first surface 11a of the metal foil 11 after the first etching mask 21 has been removed. Here, the protective layer 30 is in close contact with the inner wall 111a of the first recess. The reason for having the protective layer 30 in close contact with the inner wall 111a of the first recess in this manner is to prepare for the second-surface etching described below, and to prevent the second etching solution from flowing around to the inner wall 111a of the first recess and corroding the inner wall 111a during the second-surface etching.

[0057] The protective layer 30 is made of a first dry film resist. This is closely related to the simultaneous removal of the protective layer 30 and the second etching mask 41 from both sides of the metal foil 11 after the second-side etching process described below. That is, in the conventional two-stage etching process, as described above, a liquid photosensitive resin composition is applied to fill the first recesses 111 in preparation for the second-side etching process, and then cured to form a protective layer. In this case, when the second etching mask 41 made of the second dry film resist and the protective layer 30 made of the cured coating are simultaneously removed after the second etching process, stress (warping) occurs in the metal foil due to differences in the stripping properties (stripping speeds) of the respective stripping solutions, resulting in deformation defects. In response to this, the inventors have discovered that using a first dry film resist as the protective layer 30 improves the problem of deformation defects in metal products. The manufacturing method according to the first embodiment makes it possible to obtain metal products that suppress deformation defects while enabling the formation of high-definition through-holes by two-stage etching.

[0058] Furthermore, when the protective layer is made of a cured film of a liquid photosensitive resin composition, voids likely to occur due to insufficient curing by exposure, etc., and this tends to reduce the dimensional accuracy of the third through holes.

[0059] The protective film 30 can be attached to the first surface 11a using a laminator. In this case, for example, the first dry film resist is softened by a laminator heated to a predetermined temperature, and then attached to the first surface 11a at a predetermined pressure and a predetermined conveying speed, thereby enhancing the embedding ability of the first dry film resist and further improving the adhesion to the inner wall 111a of the first recess.

[0060] As described above, the protective layer 30 is required to have good removability (alkali solubility) against a stripping solution such as an alkaline solution, similar to the second etching mask 41 made of the second dry film resist. The protective layer 30 is also required to have the embeddability described above. Furthermore, the protective layer 30 is required to have etching resistance (strong acid resistance) so that it is not eroded by the acidic second etching solution during the second surface etching step. Furthermore, the protective layer 30 is required to have heat resistance (for example, about 120°C). The protective layer 30 made of the first dry film resist can satisfy these required characteristics. It is also preferable that the first dry film resist has excellent film thickness uniformity.

[0061] From the viewpoint of embedding properties, the melt viscosity of the first dry film resist at 70° C. is preferably in the range of 1000 to 10000 Pa·sec, and more preferably in the range of 2000 to 7000 Pa·sec.

[0062] The thickness of the protective layer 30 is preferably in the range of 10 μm to 70 μm, more preferably in the range of 10 to 40 μm. If the protective layer 30 is too thin, it will not be able to be embedded in the first recess 111 sufficiently, and adhesion will tend to be reduced. On the other hand, if the protective layer 30 is too thick, its removability with a stripping solution will be reduced. In this case, part of the dry film resist will remain on the inner wall 111a without being peeled off, which may reduce the accuracy of the opening dimensions of the through hole 12 or cause defects in the through hole. Furthermore, if the thickness of the first dry film resist is increased, it will take longer to peel the protective layer 30 from the metal foil 11.

[0063] From the viewpoint of suppressing deformation defects in the metal product 1, it is preferable that the first dry film resist constituting the protective layer 30 has the same composition and thickness as the second dry film resist constituting the second etching mask 41. In this case, when the protective layer 30 and the second etching mask 41 are simultaneously peeled off from both sides of the metal foil 11, the time required for each peeling is approximately the same, so that stress (warping) is not generated in the metal foil 11 and deformation defects in the metal product 1 can be suppressed more effectively.

[0064] <Laminating the second dry film resist> After the protective layer 30 is formed on the first surface 11a of the metal foil 11 shown in Fig. 6, a second dry film resist is attached to the second surface 11b. The structure in which the second dry film resist is formed on the second surface 11b is not shown in the figure.

[0065] The resist layer must have high resolution to accurately fabricate the second etching mask 41. Because dry film resist has high resolution and excellent film thickness uniformity, using dry film resist as the photoresist that constitutes the second etching mask contributes to obtaining a metal product 1 having a third through hole that is highly precise and has excellent dimensional accuracy.

[0066] The second dry film resist is preferably a negative photoresist. The dry film resist may be a dry film resist including a base film made of PET or the like and a photosensitive layer laminated on the base film and having photosensitivity. For example, the second dry film resist may be a dry film resist including a photosensitive material such as an acrylic photocurable resin, an epoxy photocurable resin, a polyimide photocurable resin, or a styrene photocurable resin. Of these, a dry film resist including an acrylic photocurable resin is preferred. An example of an acrylic dry film resist is Dry Film Resist RY3310 manufactured by Resonac Corporation. Alternatively, a positive dry film resist may be used as the second dry film resist.

[0067] For example, a laminator can be used to attach the second dry film resist to the second surface 11b of the metal foil 11. The thickness of the second dry film resist may be, for example, in the range of 10 μm to 70 μm.

[0068] As described above, from the viewpoint of suppressing deformation defects in the metal product 1, it is preferable that the second dry film resist has the same composition and thickness as the first dry film resist constituting the protective layer 30. In this case, the time required to peel off the protective layer 30 and the second etching mask 41 is approximately the same, so that when the protective layer 30 and the second etching mask 41 are simultaneously peeled off from both sides of the metal foil 11, stress (warping) is not generated in the metal foil 11, and deformation defects in the metal product 1 can be suppressed more effectively.

[0069] <Formation of second etching mask> 7 shows a process diagram in which a second etching mask 41 having second through holes 42 at the positions of the first recesses 111 is formed on the second surface 11b of the metal foil 11. The second etching mask 41 made of a second dry film resist can be formed by a photolithography process described below.

[0070] Here, an exposure mask that does not transmit light in the region of the second dry film resist that is to be removed, i.e., the position of the first recess 111 of the second dry film resist, is prepared and placed on the second dry film resist. Note that the structure in which the exposure mask is placed on the second dry film resist is not shown. The exposure mask is then sufficiently adhered to the second dry film resist by vacuum contact, and exposure is performed. Note that when a positive type second dry film resist is used, an exposure mask that allows light to transmit through the region of the second dry film resist that is to be removed is used.

[0071] Next, the exposed second dry film resist is developed to obtain a second etching mask 41 having second through-holes 42 at the positions of the first recesses 111 shown in FIG. 7. Development can be performed by immersing in an alkaline developer or by spraying an alkaline developer. For example, shower development, spray development, dip (immersion) development, puddle development, etc. can be used. As the alkaline developer, an aqueous solution of sodium carbonate, sodium hydroxide, etc. can be used. An antifoaming agent or a surfactant may also be added to the developer. In addition, in order to more firmly adhere the second etching mask 41 to the metal foil 11, a heat treatment process in which the second etching mask 41 is heated may be performed after the development process.

[0072] <Second surface etching process> FIG. 8 shows a process diagram in which second recesses 211 are formed on the second surface 11b of the metal foil 11 provided with the second etching mask 41 (second surface etching) at the positions of the second through holes 42.

[0073] The second surface etching is performed by wet etching, similar to the first surface etching. By supplying a second etching liquid to the second surface 11b on which the second etching mask 41 is provided, erosion of the second surface 11b progresses at the positions of the second through holes 42 that are not covered by the second etching mask 41, and second recesses 211 are formed. The second etching liquid is supplied so that the first recesses 111 and the second recesses 211 are connected at their bottoms, thereby forming third through holes. In this case, the opening diameter W3 of the constricted portion 311 is the dimension of the third through hole.

[0074] The supply of the second etching liquid to the second surface 11b is carried out, for example, similarly to the etching of the first surface, by spray etching in which the second etching liquid is sprayed toward the second surface 11b through the second etching mask 41 from a nozzle arranged on the side facing the second surface 11b of the metal foil 11 being transported. The second etching liquid may be the same as the first etching liquid.

[0075] After the second surface etching step, the protective layer 30 and the second etching mask 41 are removed. However, as described below, it is preferable to perform a second roughening treatment to roughen the inner wall 211b of the second recess prior to removing the protective layer 30 and the second etching mask 41.

[0076] <Second roughening treatment> In the manufacturing method according to the first embodiment, after the second-surface etching step, it is preferable to perform a second roughening treatment to roughen the inner wall 211b of the second recess before removing the protective layer 30 and the second etching mask 41. The metal product 1 obtained by the manufacturing method according to the first embodiment can be suitably used, for example, as a deposition mask. Here, when using a conventional deposition mask, a problem occurs in that a portion of the deposition material (organic material) emitted from the deposition source deposits on the deposition mask to form a film, which then falls off and adheres to the deposition equipment as foreign matter (particles). By performing the second roughening treatment to roughen the inner wall 211b of the second recess, it is possible to suppress the deposition material deposited on the deposition mask from falling off and prevent the deposition material from adhering to the deposition equipment as foreign matter (particles).

[0077] The roughening treatment for the inner wall 211b of the second recess can be performed by chemical etching using a microetching agent, as in the first roughening treatment. The microetching agent used here can be the same as the microetching agent described in the first roughening treatment. The second roughening treatment using a microetching agent can be performed by the same method as the first roughening treatment.

[0078] The second roughening treatment is performed so that the roughened inner wall 211b of the second recess has an arithmetic mean roughness Sa preferably in the range of 0.15 to 0.70 μm, more preferably in the range of 0.30 to 0.70 μm. If the arithmetic mean roughness Sa of the surface of the inner wall 211b is too low, the effect of suppressing the generation of foreign matter (particles) described above cannot be sufficiently obtained when the metal product 1 is used as a deposition mask. Furthermore, if the arithmetic mean roughness Sa of the inner wall 211b is too high, the second dry film resist cannot conform to the inner wall of the second recess, making voids more likely to occur.

[0079] <Removal of the protective layer and the second etching mask> Next, the protective layer 30 and the second etching mask 41 are simultaneously removed from both sides of the metal foil 11 provided with the third through holes. This results in the metal product 1 shown in FIGS. 1 and 2. The protective layer 30 and the second etching mask 41 are removed using, for example, an alkaline stripping solution. In this case, a heated alkaline stripping solution can be used. Alternatively, a stripping solution containing a strong alkaline substance such as tetraalkylammonium hydroxide can be used.

[0080] In the manufacturing method according to the first embodiment, the protective layer 30 and the second etching mask 41 are each made of dry film resist, which reduces stress (warping) that occurs in the metal foil 11 due to differences in the stripping properties (stripping speeds) of the respective stripping solutions, thereby making it possible to resolve the problem of defective deformation in the metal product 1. Furthermore, if the first dry film resist that constitutes the protective layer 30 and the second dry film resist that constitutes the second etching mask 41 are dry film resists with the same composition and thickness, the time required for stripping each will be approximately the same, making it possible to more effectively suppress defective deformation in the metal product 1.

[0081] In the metal product 1 shown in FIGS. 1 and 2, the first recess 111 and the second recess 211 are connected at their bottoms, i.e., at a constricted portion 311, and the first recess 111 and the second recess 211 form a third through hole. The opening diameter W3 of the constricted portion 311 indicates the dimension of the third through hole. As described above, the second recess 211 is preferably larger than the first recess 111. That is, the depth H2 of the second recess 211 is preferably larger than the depth H1 of the first recess 111. Furthermore, the opening diameter W2 of the second recess 211 is preferably larger than the opening diameter W1 of the first recess 111. When the depth H2 or opening diameter W2 of the second recess 211 is larger than the depth H1 or opening diameter W1 of the first recess 111, variation in the dimension of the third through hole (opening diameter W3 of the constricted portion 311) is reduced, and dimensional accuracy is improved. For the same reason, it is preferable that the difference between the opening diameter W1 of the first recess 111 and the opening diameter W3 of the third through-hole be small, and it is more preferable that they be equal.

[0082] In a cross section parallel to the thickness direction of the metal product 1 shown in FIGS. 1 and 2, the ratio H2 / H1 of the depth H2 of the second recess 211 to the depth H1 of the first recess 111 is preferably 6.5 or greater in terms of dimensional accuracy of the third through-hole. For the same reason, the ratio W2 / W1 of the opening diameter W2 of the second recess 211 to the opening diameter W1 of the first recess 111 is preferably 1.0 or greater, more preferably 1.2 or greater. On the other hand, if the ratio H2 / H1 or the ratio W2 / W1 is too large, when the metal product 1 is used as a deposition mask, the deposition material deposited on the deposition mask is likely to fall and adhere to the deposition device as foreign matter (particles). Therefore, the ratio H2 / H1 is preferably 24 or less, and the ratio W2 / W1 is preferably 2.2 or less, more preferably 1.8 or less.

[0083] 1 and 2, in a cross section parallel to the thickness direction of the metal product 1, the dimension of the third through hole (opening diameter W3 of the constricted portion 31) is smaller than both the opening diameter W1 of the first recess 111 and the opening diameter W2 of the second recess 211. Here, the preferred dimension of the third through hole is set appropriately depending on the application.

[0084] In the cross section of the metal product 1 shown in FIG. 2 , parallel to the thickness direction, L1 represents the length of a line segment connecting one end of the line segment corresponding to the opening of the first recess 111 and one end of the line segment corresponding to the opening of the second recess 211. In the metal product 1, the ratio L1 / T1 of the length L1 of the line segment to the thickness T1 is preferably 1.0 or greater, more preferably 1.2 or greater, from the viewpoint of the dimensional accuracy of the third through-hole. On the other hand, if the ratio L1 / T1 is too large, when the metal product 1 is used as a deposition mask, the deposition material deposited on the deposition mask is likely to fall and adhere to the deposition device as foreign matter (particles). Therefore, the ratio L1 / T1 is preferably 1.5 or less, more preferably 1.3 or less. The preferred range of the thickness T1 of the metal foil 11 is as described above. Specifically, the thickness T1 of the metal foil 11 is preferably 50 μm or less, more preferably 5 to 50 μm, and even more preferably 15 to 50 μm.

[0085] The metal product according to the second embodiment of the present invention is a metal product in which the inner wall 111a of the first recess in the metal product 1 shown in FIGS. 1 and 2 obtained by the manufacturing method according to the first embodiment has an arithmetic mean roughness Sa in the range of 0.30 to 0.70 μm. The metal product 1 according to the second embodiment is obtained by adding the first treatment step as an essential requirement to the manufacturing method according to the first embodiment, which includes the first roughening treatment and the second roughening treatment as optional steps, and by roughening the inner wall 111a of the first recess in the first roughening treatment step so that the arithmetic mean roughness Sa falls within the above-mentioned range. Apart from this, the metal product 1 according to the second embodiment is the same as the metal product obtained by the manufacturing method according to the first embodiment. [Example]

[0086] Tests carried out in connection with the present invention will be described below. 1. Manufacturing of metal products <Example 1> The metal product 1 shown in Figures 1 and 2 was manufactured by the following method, which will be described with reference to the process diagrams shown in Figures 3 to 8. First, a strip of SUS304 (20 μm thick) was prepared. A test piece measuring 70 mm (widthwise) and 130 mm (longitudinal) was cut from the center of the width of this SUS plate. An acrylic dry film resist (RY3310, manufactured by Resonac Corporation) was laminated onto the first surface 11a of the metal foil 11 made of the SUS plate cut out as the test piece. Next, this dry film resist was exposed and developed using a photomask to obtain a first etching mask 21 having first through holes 22 (see FIG. 3). This first etching mask 21 had one first through hole 22 at each lattice point where the square lattice pitch was 70 μm, and each first through hole 22 had a square shape when viewed from above.

[0087] Next, using a spray etching device, the first surface 11a of the metal foil 11 was etched through the etching mask 21 to form first recesses 111 on the first surface 11a at the positions of the first through holes 22 (see FIG. 4). Here, an aqueous solution containing ferric chloride as a main component was used as the etching solution, and etching was performed under conditions of a specific gravity of 1.525, a liquid temperature of 57°C, and a spray pressure of 0.30 MPa.

[0088] Next, a first roughening treatment was performed on the inner wall 111a of the first recess 111. The first roughening treatment was performed by chemically etching the inner wall 111a of the first recess using a microetching agent. The chemical etching was performed using an organic acid microetching agent (formic acid concentration: 40% by mass) at a liquid temperature of 40°C and a spray pressure of 0.4 MPa. The arithmetic mean roughness Sa of the inner wall 111a after the first roughening treatment was 0.60 μm.

[0089] Next, the first etching mask 21 was removed using an aqueous sodium hydroxide solution heated to 40° C. (See FIG. 5.) At this time, the processing time required to remove the first etching mask 21 was 20 seconds.

[0090] Next, a first dry film resist was laminated onto the first surface 11a of the metal foil 11 as the protective layer 30, and the first recesses 111 were filled with the first dry film resist. Here, the same acrylic dry film resist (RY3310, manufactured by Resonac Corporation) as the dry film resist used to form the first etching mask 21 was used as the first dry film resist. Lamination was performed using a laminator under conditions of a laminator temperature of 110°C, a pressure of 0.4 MPa, and a conveying speed of 0.3 m / min. Next, the first dry film resist was cured by exposure to light over the entire surface, forming the protective layer 30 (see FIG. 6).

[0091] Next, a second dry film resist was laminated on the second surface 11b, which is the backside of the first surface 11a of the metal foil 11. The same acrylic dry film resist (RY3310, manufactured by Resonac Corporation) as the first dry film resist was used as the second dry film resist. Next, the second dry film resist was exposed and developed using a photomask to obtain a second etching mask 41 having second through holes 42 at the positions of the first recesses 111 (see FIG. 7). This second etching mask 41 had one second through hole 42 at each lattice point where the square lattice pitch was 70 μm, and each second through hole 42 had a square shape when the etching mask 41 was viewed in plan.

[0092] Next, using a spray etching device, the second surface 11b of the metal foil 11 was etched through the second etching mask 41, and second recesses 211 were formed on the second surface 11b at the positions of the second through-holes 42 (see FIG. 8). Here, an aqueous solution containing ferric chloride as a main component was used as the etching solution, and etching was performed under conditions of a specific gravity of 1.555, a liquid temperature of 53°C, and a spray pressure of 0.4 MPa. The second recesses 211 and the first recesses 111 are connected at their bottoms by a constricted portion 311, and the second recesses 211 and the first recesses 111 form third through-holes (see FIGS. 1, 2, and 8).

[0093] Next, a second roughening treatment was performed on the inner wall 211b of the second recess. The second roughening treatment was performed by chemically etching the inner wall 211b of the second recess using a microetching agent. The chemical etching was performed using an organic acid microetching agent (formic acid concentration: 40% by mass) at a liquid temperature of 40°C and a spray pressure of 0.4 MPa. The arithmetic mean roughness Sa of the inner wall 211b after the second roughening treatment was 0.59 μm.

[0094] Next, the protective layer 30 and the second etching mask 41 were simultaneously removed from both sides of the metal foil 11 using a sodium hydroxide solution heated to 40°C, thereby obtaining a metal product 1 (see FIGS. 1 and 2). At this time, the time required to remove the protective layer 30 and the second etching mask 41 was approximately the same, and the processing time was 25 seconds.

[0095] The metal product 1 obtained in this example had a third through hole formed by connecting at the bottom a first recess 111 having a square opening with a side length (W1) of 52 μm when viewed from the first surface 11a and a second recess 211 having a square opening with a side length (W2) of 64 μm when viewed from the second surface 11b. The dimension of the third through hole (opening diameter W3 of the constricted portion 311) was 48.70 μm, and 3σ (σ: standard deviation), which indicates the dimensional variation, was 1.00 μm.

[0096] <Example 2> A metal product was produced in the same manner as in Example 1, except that the concentration of the microetching agent was changed from 40% by mass to 3% by mass.

[0097] <Example 3> A metal product was produced in the same manner as in Example 1, except that the concentration of the microetching agent was changed from 40% by mass to 15% by mass.

[0098] <Example 4> A metal product was produced in the same manner as in Example 1, except that the concentration of the microetching agent was changed from 40% by mass to 20% by mass.

[0099] <Example 5> A metal product was produced in the same manner as in Example 1, except that the concentration of the microetching agent was changed from 40% by mass to 50% by mass.

[0100] <Example 6> A metal product was manufactured in the same manner as in Example 1, except that the first roughening treatment was not performed. That is, in this example, after forming the first recesses 111 by etching (see FIG. 4), the step of removing the first etching mask 21 was carried out without performing the first roughening treatment on the inner walls 111a of the first recesses. In this case, the arithmetic mean roughness Sa of the inner walls 111a was 0.10 μm.

[0101] <Comparative Example 1> A metal product was manufactured in the same manner as in Example 1, except that, instead of an acrylic dry film resist (RY3310, manufactured by Resonac Co., Ltd.), a cured coating film was used as the protective layer 30, which was formed by applying a liquid photosensitive resin varnish and curing it by exposing the entire surface to light.

[0102] <2. Measurement and calculation methods> <2.1 Dimensions and dimensional accuracy 3σ of the third through hole> Each metal product 1 obtained above had a third through-hole at each lattice point of a square lattice in a test piece measuring 130 mm (longitudinal) x 70 mm (width) cut out from a stainless steel plate. The third through-holes were arranged in a square lattice pattern of 1,600 (longitudinal) x 850 (width) holes on each lattice of the 70 μm-pitch square lattice. The dimensions of these third through-holes (opening diameter W3) were measured in transmitted light mode, with the first surface 11a (small hole side) of the metal product 1, on which the first recesses 111 were formed, positioned toward the light source.

[0103] The measurement locations were determined by dividing the opening pattern of the third through holes into 364 small areas of 5 mm x 5 mm (26 locations (longitudinal) x 14 locations (widthwise)), selecting 25 consecutively arranged openings (5 x 5 locations) for each small area, and measuring the dimensions of the third through holes (opening diameter W3). From these measurements, the dimensions (average value) and dimensional accuracy 3σ (σ: standard deviation) of the third through holes were calculated.

[0104] 2.2 Measurement of arithmetic mean roughness Sa The arithmetic mean roughness Sa of the roughened surface was measured using a three-dimensional white light interference microscope according to the method specified in ISO 25178. In this example, the smooth portion of the small hole surface after roughening was used as the value for the opening wall surface.

[0105] <2.3 Deformation defect inspection> Under indoor fluorescent lighting, metal product 1 is held up to the inspector's eye level, and the light from the fluorescent light is reflected, and the metal product 1 is inspected at different angles. If a streak-like deformation of 10 mm or more is found, it is counted as 1. Five samples were used, and the average number of defective deformations counted per sample was calculated.

[0106] For each example and Comparative Example 1, the incidence rate (%) of deformation defects in the metal product, the dimensions of the third through holes (opening diameter W1 of the constricted portion) (μm), the dimensional accuracy 3σ (nm) of the third through holes, the arithmetic mean roughness Sa of the first recesses 111 after the first roughening treatment, and the arithmetic mean roughness Sa of the second recesses 211 after the first roughening treatment were measured or calculated according to the measurement method and / or calculation method described above. The results are summarized in Table 1.

[0107] [Table 1]

[0108] A comparison of Examples 1 to 6 with Comparative Example 1 in Table 1 shows that the occurrence rate of deformation defects in metal products was significantly reduced by using a dry film resist as the protective layer 30 instead of a cured coating film of a liquid photosensitive composition, and by selecting this dry film resist as the same as the dry film resist that constitutes the second etching mask 41. A comparison of Examples 1 to 6 also shows that the dimensional accuracy of the third through hole was improved by adjusting the arithmetic mean roughness Sa of the inner wall 111a of the first recess within a specific range by the first roughening treatment. [Explanation of symbols]

[0109] 1...metal product, 11...metal foil, 11a...first surface, 11b...second surface, 21...first etching mask, 22...first through hole, 30...first dry film resist (protective layer), 41...second etching mask, 42...second through hole, 111...first recess, 111a...inner wall of first recess, 211...second recess, 211b...inner wall of second recess, 311...necked portion

Claims

1. Providing a metal foil having a first surface and a second surface opposite to the first surface; forming a first etching mask on the first surface, the first etching mask having a first through hole; supplying a first etching liquid to the first surface on which the first etching mask is provided, to form a first recess in the first surface at the position of the first through hole; removing the first etching mask from the first surface; a protective layer made of a first dry film resist is attached to the first surface, and the protective layer is brought into close contact with an inner wall of the first recess; laminating a second dry film resist to the second surface; forming second through holes in the second dry film resist at positions of the first recesses to obtain a second etching mask; supplying a second etching liquid to the second surface on which the second etching mask is provided, to form a second recess in the second surface at the position of the second through hole, and a third through hole formed by connecting the first recess and the second recess at their bottoms; simultaneously removing the protective layer and the second etching mask from the metal foil in which the third through holes are provided; A method for manufacturing metal products including:

2. 2. The method for manufacturing a metal product according to claim 1, wherein the protective layer and the second etching mask are simultaneously removed from the metal foil using an alkaline solution as a stripping solution.

3. 2. The method for manufacturing a metal product according to claim 1, wherein the first dry film resist and the second dry film resist have the same composition and thickness.

4. 2. The method for manufacturing a metal product according to claim 1, wherein the metal foil has a thickness in the range of 15 to 50 [mu]m.

5. The method for manufacturing a metal product according to claim 1 , further comprising performing a first roughening treatment to roughen the inner wall of the first recess prior to removing the first etching mask from the first surface.

6. 6. The method for manufacturing a metal product according to claim 5, wherein the first roughening treatment is performed so that the roughened inner wall of the first recess has an arithmetic mean roughness Sa within a range of 0.30 to 0.70 μm.

7. The method for manufacturing a metal product according to claim 1 , further comprising performing a second roughening treatment to roughen the inner wall of the second recess prior to removing the protective layer and the second etching mask from the metal foil.

8. 8. The method for manufacturing a metal product according to claim 7, wherein the second roughening treatment is performed so that the roughened inner wall of the second recess has an arithmetic mean roughness Sa within a range of 0.30 to 0.70 μm.

9. The method for manufacturing a metal product according to claim 1 , wherein the first recess and the second recess are formed such that the second recess has a greater depth than the first recess.

10. The method for manufacturing a metal product according to any one of claims 1 to 9, wherein a deposition mask is obtained as the metal product.

11. It has a first surface and a second surface that is the reverse side of the first surface, a first recess in the first surface that tapers toward the second surface; a second recess tapering toward the first surface is provided in the second surface; the first recess and the second recess are connected at the position of their bottoms to form a through hole, The inner wall of the first recess has an arithmetic mean roughness Sa in the range of 0.30 to 0.70 μm.

12. The metal product according to claim 11, wherein the inner wall of the second recess has an arithmetic mean roughness Sa within a range of 0.30 to 0.70 μm.

13. 12. The metal product of claim 11, wherein the second recess has a greater depth than the first recess.

14. 12. The metal product of claim 11, having a thickness in the range of 15 to 50 [mu]m.

15. 15. The metal product according to claim 12, which is a deposition mask.

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