Metal mask, method for manufacturing metal mask, and base material

Abstract

This metal mask is used when forming an internal electrode of a multilayer ceramic capacitor, wherein a through-hole is formed in a metal base material, the arithmetic average height Sa of at least one surface of the base material is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more.

Description

Metal mask, method for manufacturing metal mask, and substrate

[0001] The present invention relates to a metal mask, a method for manufacturing a metal mask, and a substrate. This application claims priority based on Japanese Patent Application No. 2024-195242 filed in Japan on November 7, 2024, and incorporates its content herein by reference.

[0002] A multilayer ceramic capacitor (hereinafter sometimes referred to as MLCC) is a chip component type capacitor in which internal electrodes and dielectric layers are laminated in multiple layers. While MLCCs are required to be miniaturized, they are also required to increase their capacitance. In order to increase the capacitance while miniaturizing the MLCC, it is necessary to reduce the film thickness of the internal electrodes and increase the number of lamination layers. Conventionally, the internal electrodes have been formed by screen printing, but by forming them by a physical vapor deposition method such as sputtering using a metal mask having a plurality of through holes, thin internal electrodes can be formed, so it is expected that the capacitance can be increased while miniaturizing the MLCC (for example, Patent Document 1).

[0003] International Publication No. 2005 / 117040

[0004] When forming internal electrodes using physical vapor deposition (VA) with a metal mask, deposits of the material constituting the internal electrodes accumulate on the side of the metal mask facing the target (hereinafter referred to as the first surface). Therefore, if one metal mask is repeatedly used to form internal electrodes, the deposits on the first surface become thicker. If the deposits on the first surface become too thick, they may peel off and float around inside the deposition apparatus (corresponding to the sputtering apparatus described later), covering the surface of the substrate when the internal electrodes are deposited. This could result in the formation of undeposited areas (voids) within the internal electrodes. Furthermore, if the peeled deposits fall onto the target, there is a risk of a short circuit between the target (the cathode) and the grounded frame, causing the deposition apparatus to stop. Therefore, when repeatedly using one metal mask to form internal electrodes, it is necessary to periodically clean the first surface to remove the deposits. Consequently, to increase the productivity of internal electrodes, it is necessary to reduce the frequency of cleaning the first surface.

[0005] Based on the above circumstances, the present invention aims to provide a metal mask that can reduce the frequency of cleaning the first surface, a method for manufacturing a metal mask, and a substrate.

[0006] To solve the above problems, this invention proposes the following means. The first aspect of the present invention is a metal mask used when forming internal electrodes of a multilayer ceramic capacitor, having through holes formed in a metal substrate. This metal mask has an arithmetic mean height Sa of at least one surface of the substrate of 0.10 μm or more, and a maximum height Sz of 2.56 μm or more.

[0007] A second aspect of the present invention is a method for manufacturing a metal mask used when forming internal electrodes of a multilayer ceramic capacitor, wherein through holes are formed in a metal substrate. In this method for manufacturing the metal mask, the arithmetic mean height Sa of at least one surface of the substrate is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more.

[0008] A third aspect of the present invention is a metallic substrate that constitutes a metal mask used when forming internal electrodes of a multilayer ceramic capacitor. This substrate has an arithmetic mean height Sa of at least one surface of 0.10 μm or more, and a maximum height Sz of 2.56 μm or more.

[0009] According to the present invention, it is possible to provide a metal mask that can reduce the frequency of cleaning the first surface of the metal mask, a method for manufacturing a metal mask, and a substrate.

[0010] This is a plan view of a metal mask according to one embodiment of the present invention. This is a schematic cross-sectional view of a sputtering apparatus using a metal mask according to one embodiment of the present invention. This is a schematic enlarged cross-sectional view of the short side direction of a through hole in a metal mask according to one embodiment of the present invention. This is a flowchart of a method for manufacturing a metal mask according to one embodiment of the present invention. This is a first figure showing the relationship between the surface roughness of a first surface and the adhesion strength of a deposit to the first surface according to one embodiment of the present invention. This is a second figure showing the relationship between the surface roughness of a first surface and the adhesion strength of a deposit to the first surface according to one embodiment of the present invention.

[0011] One embodiment of the present invention will be described with reference to Figures 1 to 6. The dimensions and other details in the figures illustrated in the following description are examples only, and the present invention is not necessarily limited to them. It can be implemented with appropriate modifications without changing the essence of the invention. In addition, in the following drawings, the scale and number of each structure may differ from the actual structure in order to make each structure easier to understand.

[0012] In each drawing, the Z-axis is indicated as appropriate. In this embodiment, the direction in which the Z-axis extends is the direction in which the surface of the metal mask faces. In the following description, the direction in which the surface of the metal mask faces will be simply referred to as the "thickness direction." In the following description, the side of the thickness direction in which the Z-axis arrow points (+Z side) will be referred to as the "front side," and the side of the thickness direction in which the Z-axis arrow points (-Z side) will be referred to as the "back side." Note that the front side and back side are merely names used to describe the relative positional relationships of the parts of the metal mask, and the actual arrangement relationships may be other than those indicated by these names.

[0013] In each drawing, the X-axis is indicated as appropriate. In this embodiment, the direction in which the X-axis extends is the longitudinal direction of the metal mask in Figure 1. In the following description, the longitudinal direction of the metal mask will simply be referred to as the "longitudinal direction." The longitudinal direction is perpendicular to the thickness direction.

[0014] In each drawing, the Y-axis is indicated as appropriate. In this embodiment, the direction in which the Y-axis extends is the short-side direction of the metal mask in Figure 1. In the following description, the short-side direction of the metal mask will simply be referred to as the "short-side direction". The short-side direction is perpendicular to both the thickness direction and the length direction.

[0015] Figure 1 is a plan view of the metal mask 10 according to this embodiment. The shape of the through-hole 12, which will be described later, is basically rectangular in plan view, but it does not have to be rectangular. In this embodiment, the longer side direction of the through-hole 12 is the longitudinal direction (X-axis direction), and the shorter side direction of the through-hole 12 is the short side direction (Y-axis direction). In the case of a metal substrate 11 that has been rolled, the longitudinal direction is the rolling direction. Figure 2 is a schematic cross-sectional view of a sputtering apparatus 20 using the metal mask 10 according to this embodiment. Figure 3 is a schematic enlarged cross-sectional view of the short side direction of the through-hole 12 of the metal mask 10 according to this embodiment. The metal mask 10 of this embodiment shown in Figure 1 is a mask used when forming the internal electrodes 28 of a multilayer ceramic capacitor (MLCC) shown in Figure 2. The internal electrodes 28 are formed by physical vapor deposition (PVD). In this embodiment, the internal electrodes 28 are formed by sputtering. The internal electrodes 28 may also be formed by other physical vapor deposition methods such as vapor deposition.

[0016] As shown in Figure 1, the metal mask 10 is plate-shaped with its surface facing the thickness direction (Z-axis direction). The metal mask 10 is composed of a plate-shaped metal base material 11. That is, the base material 11 constitutes the metal mask 10. If the base material 11 is attracted by a magnet during sputtering, it is made of a magnetic alloy. In this embodiment, the base material 11 is made of SUS430. The base material 11 is a thin-film metal base material manufactured by rolling. The base material 11 is plate-shaped with its length extending in a direction perpendicular to the thickness direction. In this embodiment, the base material 11 is substantially rectangular with its long side extending in the longitudinal direction (X-axis direction). If the base material 11 is not attracted by a magnet during sputtering and can be fixed by another method, the base material 11 may be made of SUS304.

[0017] The thickness of the metal mask 10 is preferably 20 μm or more and 100 μm or less. The thickness of the metal mask 10 may be less than 20 μm or more than 100 μm. The dimension of the metal mask 10 in the longitudinal direction (X-axis direction) is, for example, 600 mm. The dimension of the metal mask 10 in the short direction (Y-axis direction) is, for example, 500 mm. The dimensions of the metal mask 10 are not limited to these. As shown in Figure 3, the substrate 11 has a first surface 11a and a second surface 11c.

[0018] The first surface 11a is one surface of the substrate 11 facing the surface side (+Z side). In this embodiment, the arithmetic mean height Sa of the first surface 11a, i.e., one surface of the substrate 11, is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more. Also in this embodiment, the difference between the maximum height Sz and the arithmetic mean height Sa of the first surface 11a is 2.46 μm or more. Also in this embodiment, the arithmetic mean curvature Spc of the peak of the first surface 11a is 1848.21 mm －１That concludes the description. In this embodiment, the unfolded area ratio Sdr of the interface of the first surface 11a is 0.05 or more. In this embodiment, the arithmetic mean roughness Ra of the first surface 11a is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more. In this embodiment, the difference between the maximum height roughness Rz and the arithmetic mean roughness Ra of the first surface 11a is 0.76 μm or more. By setting each of the above parameters related to the surface roughness of the first surface 11a within the above range, the adhesion strength between the deposited material constituting the internal electrode 28 (hereinafter sometimes referred to as deposited material S) deposited on the first surface 11a and the first surface 11a can be increased when forming the internal electrode 28. The first surface 11a is subjected to a roughening treatment in the roughening treatment step P01 described later.

[0019] The second surface 11c is the other surface of the substrate 11 facing the back side (-Z side). The surface roughness of the second surface 11c is not particularly limited. The range of each of the above parameters related to the surface roughness of the second surface 11c may be the same as that of the first surface 11a, or it may be a different range from that of the first surface 11a. The second surface 11c may or may not be subjected to a roughening treatment.

[0020] As shown in Figure 1, the base material 11 has a plurality of through holes 12 formed therein. Each through hole 12 is a hole that penetrates the base material 11 in the thickness direction (Z-axis direction). Viewed from the thickness direction, each through hole 12 is substantially rectangular in shape with its longer side extending in the longitudinal direction (X-axis direction). The longitudinal dimensions of each through hole 12 are preferably between 250 μm and 1700 μm, assuming a two-sided chamfer in the short-side direction (Y-axis direction), for example, from 016008 size (0.16 mm × 0.08 mm) to 0603 size (0.6 mm × 0.3 mm). The short-side dimensions of each through hole 12 are preferably between 35 μm and 400 μm, assuming a two-sided chamfer in the short-side direction, for example, from 016008 size (0.16 mm × 0.08 mm) to 0603 size (0.6 mm × 0.3 mm). The longitudinal dimension of each through-hole 12 is preferably greater than twice the transverse dimension. In this case, the internal electrodes 28 are mounted on two surfaces in the longitudinal direction. The dimensions of each through-hole 12 are not limited to these. The longitudinal pitch in which each through-hole 12 is formed is, for example, 2 mm. The transverse pitch in which each through-hole 12 is formed is, for example, 1 mm. The longitudinal and transverse pitches in which each through-hole 12 is formed are not limited to these. Each through-hole 12 is formed by a wet etching process in the through-hole formation process P02 described later.

[0021] As described above, in this embodiment, the internal electrodes 28 of the MLCC are formed by sputtering. As shown in Figure 2, the sputtering apparatus 20 has a tray 21, a magnet 22, and a target 23.

[0022] The tray 21 is a container-shaped structure that opens towards the target 23, i.e., the surface side (+Z side). Inside the tray 21 are the carrier film 25, the green sheet 26, and the metal mask 10. The magnet 22 is fixed to the side of the tray 21 that faces away from the target 23. The target 23 is positioned on the surface side of the tray 21. In this embodiment, the target 23 is, for example, nickel. The target 23 may also be a nickel alloy mainly composed of nickel, containing aluminum, silver, copper, and platinum, etc.

[0023] The carrier film 25 holds the green sheet 26. The carrier film 25 is a film that extends in a direction perpendicular to the thickness direction (Z-axis direction). The carrier film 25 has an adhesive coating on both the back side (-Z side) and the front side (+Z side). The carrier film 25 is attached to the bottom surface of the tray 21. The carrier film 25 is removable from the bottom surface of the tray 21.

[0024] The green sheet 26 is a sheet that extends in a direction perpendicular to the thickness direction of the sheet. In an MLCC, the green sheet 26 plays the role of a dielectric layer. In this embodiment, the green sheet 26 is formed by coating the surface of a carrier film 25, which is a PET sheet, with a slurry mainly composed of barium titanate using a die-coating method or a doctor blade method, and then drying it, resulting in a layer with a thickness of approximately 1 μm. The green sheet 26 may be made of other materials. The side of the green sheet 26 that faces away from the target 23 is attached to the carrier film 25. The green sheet 26 is peelable from the carrier film 25. A release layer is provided on the side of the carrier film 25 that faces the green sheet 26, and the carrier film 25 is also called a release film.

[0025] The metal mask 10 is positioned on the front side (+Z side) of the green sheet 26. In this embodiment, the first surface 11a of the base material 11, that is, one side of the base material 11, is positioned facing the target 23. As described above, the metal mask 10 is often made of a magnetic alloy. Therefore, the magnet 22 applies a magnetic force to the metal mask 10 that is directed toward the back side (-Z side). As a result, the second surface 11c of the metal mask 10 adheres closely to the green sheet 26.

[0026] The vacuum chamber (not shown) of the sputtering apparatus 20 is evacuated using a vacuum pump to create a vacuum. After introducing a small amount of an inert gas such as argon, a voltage of several hundred volts is applied, with the vacuum chamber side as the anode and the target side as the cathode. The argon gas discharges, becoming positive ions, which are rapidly attracted to the target 23 (the cathode) and collide with it. This causes nickel atoms on the surface of the target 23 to be ejected, and nickel atoms fly from the target 23 towards the green sheet 26. Some of the nickel atoms that fly towards the green sheet 26 pass through each through-hole 12 of the metal mask 10 and deposit on the surface of the green sheet 26. As a result, internal electrodes 28 are formed on the portion of the green sheet 26 facing each through-hole 12. In this embodiment, the thickness of the internal electrodes 28 formed on the surface of the green sheet 26 is approximately 150 nm. Once the desired thickness of internal electrodes 28 is formed on the surface of the green sheet 26, the application of voltage to the target 23 and the vacuum chamber is terminated. When the green sheet 26 is peeled off from the carrier film 25, an MLCC is manufactured using the green sheet 26 on which multiple internal electrodes 28 are formed.

[0027] As described above, some of the nickel atoms that fly toward the green sheet 26 pass through each through-hole 12 of the metal mask 10 and are deposited on the surface of the green sheet 26. In contrast, some of the nickel atoms that fly toward the green sheet 26 adhere to the first surface 11a of the metal mask 10 and the inner surface of the through-holes 12 on the first surface 11a side. As a result, nickel deposits S are deposited on the first surface 11a and the inner surface of the through-holes 12 on the first surface 11a side. When one metal mask 10 is used repeatedly to form the internal electrode 28, the deposits S deposited on the first surface 11a and the inner surface of the through-holes 12 on the first surface 11a side become thicker. In this embodiment, as described above, the first surface 11a of the metal mask 10 is subjected to a roughening treatment, and the above parameters related to the surface roughness of the first surface 11a are within the above range. Therefore, the anchoring effect of the deposits S on the first surface 11a can be enhanced. As a result, the adhesive strength between the first surface 11a and the deposits S can be increased. As shown in Figure 1, the area of ​​the first surface 11a is larger than the area of ​​the inner surface of the through hole 12 on the first surface 11a side. Therefore, the peeling of the deposit S from the metal mask 10 can be effectively suppressed. When forming the internal electrode 28, if the deposit S peels off particularly from the first surface 11a and floats around inside the sputtering apparatus 20 shown in Figure 2, covering the surface of the green sheet 26, and the internal electrode 28 is formed, there is a risk that unfilmed portions (referred to as voids in the following explanation) will occur inside the internal electrode 28. Also, if the deposit S peeled off from the first surface 11a falls onto the target 23, there is a risk that the target 23, which is the cathode, and a grounded frame (not shown) will short-circuit, causing the sputtering apparatus 20 to stop. In this embodiment, as described above, the peeling of the deposit S from the metal mask 10 can be suppressed, so the occurrence of voids in the formed internal electrode 28 can be suppressed, and the stopping of the sputtering apparatus 20 can be suppressed. Therefore, in this embodiment, the shape of the internal electrode 28 can be suitably stabilized, making it possible to obtain an internal electrode 28 with good accuracy in the superposition of MLCCs.

[0028] Next, the manufacturing method Pm for the metal mask 10 of this embodiment will be described. As shown in Figure 4, the manufacturing method Pm for the metal mask 10 of this embodiment includes a surface roughening step P01 in which a surface roughening treatment is applied to the first surface 11a of the base material 11, that is, one surface of the base material 11, and a through-hole forming step P02 in which a plurality of through-holes 12 are formed in the base material 11. In this specification, "workers, etc." includes workers and equipment, etc. who perform the work in each step of the manufacturing method Pm for the metal mask 10, and who perform the adhesion strength test between the first surface 11a and the deposit S, which will be described later. The work in each step may be performed by workers alone, by equipment alone, or by workers and equipment together.

[0029] In the roughening treatment step P01, the worker applies a roughening treatment to the first surface 11a of the base material 11, that is, one surface of the base material 11. In the roughening treatment step P01, the roughening treatment may also be applied to the second surface 11c of the base material 11, or it may not be applied to the second surface 11c. In other words, in the roughening treatment step P01, it is sufficient to apply the roughening treatment to at least the first surface 11a. In the roughening treatment step P01, the method of applying the roughening treatment to the first surface 11a is not particularly limited. For example, the first surface 11a may be polished with a file, or the base material 11 may be chemically polished by immersing it in an acidic liquid such as sulfuric acid or hydrochloric acid. When workers polish the first surface 11a with a file, they can adjust the roughness of the first surface 11a after the roughening treatment by appropriately setting the grit size of the file (hereinafter referred to as the grit number) and the number of times the same area of ​​the first surface 11a is polished. Also, when workers chemically polish the first surface 11a by immersing the substrate 11 in an acidic liquid, they can adjust the roughness of the first surface 11a after the roughening treatment by appropriately adjusting the immersion time. In addition, when the first surface 11a is chemically polished by immersing the substrate 11 in a liquid in the roughening treatment process P01, the second surface 11c is also subjected to the roughening treatment. If the second surface 11c is not subjected to the roughening treatment, a protective film that is not affected by acid can be appropriately selected and applied to the second surface 11c.

[0030] In this embodiment, when the roughening process P01 is completed, the arithmetic mean height Sa of the first surface 11a is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more. That is, in the manufacturing method Pm of the metal mask 10 of this embodiment, the arithmetic mean height Sa of at least the first surface 11a, i.e., at least one surface of the substrate 11, is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more. Also, when the roughening process P01 is completed, the arithmetic mean roughness Ra of the first surface 11a is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more. In other words, in the manufacturing method Pm of the metal mask 10 of this embodiment, the arithmetic mean roughness Ra of the first surface 11a, i.e., one surface of the substrate 11, is set to 0.08 μm or more, and the maximum height roughness Rz is set to 0.85 μm or more. Furthermore, the difference between the maximum height Sz and the arithmetic mean height Sa of the first surface 11a is 2.46 μm or more. The arithmetic mean curvature Spc of the peak of the first surface 11a is 1848.21 mm. －１ That concludes the findings. The unfolded area ratio Sdr of the interface of the first surface 11a is 0.05 or greater. The difference between the maximum height roughness Rz and the arithmetic mean roughness Ra of the first surface 11a is 0.76 μm or greater.

[0031] In the through-hole formation step P02, the worker forms a plurality of through-holes 12 in the substrate 11. As shown in Figure 4, in this embodiment, the through-hole formation step P02 includes a first etching step P021 in which etching is performed on the second surface 11c of the substrate 11, and a second etching step P022 in which etching is performed on the first surface 11a of the substrate 11. In this embodiment, a plurality of through-holes 12 are formed by a so-called two-stage etching process, in which wet etching is performed separately on the second surface 11c and the first surface 11a of the substrate 11.

[0032] In the first etching step P021, the operator performs an etching process on the second surface 11c of the substrate 11. First, the operator adheres a resist (not shown) to both the second surface 11c and the first surface 11a of the substrate 11. Next, the operator exposes and develops both sides of the substrate 11 using an exposure mask to create multiple holes in the resist. The multiple holes formed in the resist are formed in positions and shapes corresponding to the through holes 12 formed in the metal mask 10. After that, the operator laminates the resist with holes on the first surface 11a side of the substrate 11 with a protective film, and then performs an etching process on the second surface 11c of the substrate 11. When holes of the desired shape and depth are formed on the second surface 11c of the substrate 11, the operator finishes the etching process on the second surface 11c. When the operator removes the resist provided on the second surface 11c, the first etching step P021 is completed.

[0033] In the second etching step P022, the worker protects the second surface 11c of the substrate 11 with an etching-resistant resin such as a gravure coat. After that, the worker removes the protective film of the resist having holes on the first surface 11a side, and then performs an etching process on the first surface 11a of the substrate 11 through the resist having holes on the first surface 11a side. When holes of the desired shape and depth are formed on the first surface 11a of the substrate 11, and these holes connect with the holes formed on the second surface 11c to form through-holes 13 as shown in Figure 3, the worker completes the etching process on the first surface 11a. After that, the worker removes the resist having holes on the first surface 11a side of the substrate 11, and the etching-resistant resin protecting the second surface 11c of the substrate 11, and the second etching step P022 is completed. When the second etching step P022 is completed, the through-hole formation step P02 is completed. At this time, the substrate 11 has a plurality of through-holes 12 as shown in Figures 1 and 3. Once multiple through holes 12 are formed in the base material 11, the metal mask 10 is completed.

[0034] As described above, in the through-hole formation step P02, when the second surface 11c and the first surface 11a are etched, a resist (not shown) is in close contact with each of the first surface 11a and the second surface 11c. This prevents the etching solution from adhering to parts of the first surface 11a and the second surface 11c other than the parts where multiple through-holes 12 are formed during the through-hole formation step P02. Therefore, the surface roughness of the first surface 11a and the second surface 11c of the substrate 11 in the completed metal mask 10 is the same as the surface roughness of the first surface 11a and the second surface 11c of the substrate 11 at the time the roughening treatment step P01 is completed.

[0035] As shown in Figure 3, the dimensions of the through-hole 12 formed in the base material 11, when viewed from the thickness direction (Z-axis direction), are smallest at the through-hole portion 13 in the middle of the thickness direction of the base material 11. In this embodiment, the shape and dimensions of the through-hole portion 13 when viewed from the thickness direction are the same as the shape and dimensions of the through-hole 12 shown in Figure 1.

[0036] The etching method in the through-hole formation step P02 is not limited to this embodiment. Multiple through-holes 12 may be formed by a so-called one-stage etching process, in which etching is performed simultaneously on both the second surface 11c and the first surface 11a of the substrate 11. Alternatively, etching may be performed on the first surface 11a first, followed by etching on the second surface 11c.

[0037] In this embodiment, the maximum height Sz of the first surface 11a is preferably 10.0 μm or less. If the maximum height Sz of the first surface 11a is greater than 10.0 μm, the roughness of the first surface 11a becomes too large, making it difficult for the etching solution to uniformly enter the through-hole 12 in the second etching step P022. As a result, the shape of the through-hole 12 becomes unstable. In this embodiment, by setting the maximum height Sz of the first surface 11a to 10.0 μm or less, the etching solution can easily enter the through-hole 12 uniformly. This makes it possible to stabilize the shape of the through-hole 12. For similar reasons, the maximum height roughness Rz of the first surface 11a is preferably 5.0 μm or less.

[0038] Figure 5 is the first figure showing the relationship between the three-dimensional surface roughness of the first surface 11a and the adhesion strength of the sediment S to the first surface 11a according to this embodiment. Figure 6 is the second figure showing the relationship between the two-dimensional surface roughness of the first surface 11a and the adhesion strength of the sediment S to the first surface 11a according to this embodiment. The three-dimensional surface roughness is measured according to ISO 25178 Surface properties (surface roughness measurement), and the two-dimensional surface roughness is measured according to JIS standard JIS B 0601:2001. Next, the relationship between each parameter related to the surface roughness of the first surface 11a in this embodiment and the adhesion strength between the first surface 11a and the sediment S will be explained.

[0039] Metal masks with different surface roughening methods for the first surface 11a in the surface roughening process P01 described above were prepared as Examples 1 to 21 and Comparative Examples 1 to 6, according to the specifications shown in Figures 5 and 6. The preparation procedure for each sample is described below. The material of the base material 11 for each sample was SUS430.

[0040] In the samples of Examples 1 to 12 and Comparative Examples 1 to 3, the first surface 11a was polished using a file in the roughening treatment step P01. For this polishing process, a roughly rectangular sponge file with one side measuring 20 mm and the other side measuring 35 mm was used. The pressure applied to the first surface 11a with the file was 300 gf. The file's movement speed was 15 cm / second. The operator polished the first surface 11a by moving the file 20 times in the longitudinal direction (X-axis direction), 20 times in the short direction (Y-axis direction), and in a circular motion so that the amount of polishing per unit area was the same when viewed from the plate thickness direction (Z-axis direction). In Examples 1 to 3, the first surface 11a was polished using a file with a grit of 120 (#120). In Examples 4 to 6, the first surface 11a was polished using a file with a grit of 240 (#240). In Examples 7 to 9, the first surface 11a was polished using a file with a grit of 400 (#400). In Examples 10 to 12, the first surface 11a was polished using a file with a grit of 800 (#800). In Comparative Examples 1 to 3, the first surface 11a was polished using a file with a grit of 4000 (#4000).

[0041] In the samples of Examples 13 to 21, in the roughening treatment step P01, the base material 11 was immersed in a liquid having acidity such as sulfuric acid and hydrochloric acid, and chemical polishing was performed on the first surface 11a. In such chemical polishing, hydrochloric acid at room temperature was used as the liquid. In Examples 13 to 15, chemical polishing of the first surface 11a was performed with an immersion time of 20 seconds. In Examples 16 to 18, chemical polishing of the first surface 11a was performed with an immersion time of 40 seconds. In Examples 19 to 21, chemical polishing of the first surface 11a was performed with an immersion time of 90 seconds. In Comparative Examples 4 to 6, the roughening treatment step P01 was not performed. That is, in Comparative Examples 4 to 6, the first surface 11a was not subjected to roughening treatment.

[0042] Next, workers and the like measured each parameter related to the surface roughness of the first surface 11a of each of the samples of Examples 1 to 21 and Comparative Examples 1 to 6, that is, the arithmetic mean height Sa, the maximum height Sz, the arithmetic mean curvature Spc of the peak points, the developed area ratio Sdr of the interface, the arithmetic mean roughness Ra, and the maximum height roughness Rz. In the present embodiment, the measurement of each parameter related to the surface roughness of the first surface 11a was performed using a laser microscope VK-X3000 manufactured by Keyence Corporation. The magnification of the objective lens was 50 times. The measurement range (field of view) was 210 μm × 150 μm. FIG. 5 shows the arithmetic mean height Sa, the maximum height Sz, the difference (Sz - Sa) between the maximum height Sz and the arithmetic mean height Sa, the arithmetic mean curvature Spc of the peak points, and the developed area ratio Sdr of the interface of the first surface 11a in Examples 1 to 21 and Comparative Examples 1 to 6. FIG. 6 shows the arithmetic mean roughness Ra, the maximum height roughness Rz, and the difference (Rz - Ra) between the maximum height roughness Rz and the arithmetic mean roughness Ra of the first surface 11a in Examples 1 to 21 and Comparative Examples 1 to 6.

[0043] Next, the operator or the like performed each operation of the through-hole forming step P02 on each sample of Examples 1 to 21 and Comparative Examples 1 to 6 according to the above-described procedure, and formed a plurality of through-holes 12 in each of the samples. Next, the operator or the like formed the internal electrodes 28 by repeatedly using each sample of Examples 1 to 21 and Comparative Examples 1 to 6 in the above-described sputtering apparatus 20, and formed a deposit S having a predetermined thickness on the first surface 11a of each sample. In the present embodiment, deposits S having thicknesses of 0.15 μm, 4.0 μm, and 7.0 μm were formed on the first surface 11a of each sample.

[0044] Next, a test method for the adhesion strength between the first surface 11a and the deposit S will be described. In the present embodiment, each of the tests 1 to 4 was performed on each sample of Examples 1 to 21 and Comparative Examples 1 to 6, and the adhesion strength between the first surface 11a and the deposit S of each sample was evaluated. In Test 1, the operator or the like performed a cross-cut adhesion test defined in JIS-K5600 on the deposit S having a thickness of 0.15 μm formed on each sample. In Test 2, the operator or the like performed a cross-cut adhesion test defined in JIS-K5600 on the deposit S having a thickness of 4.0 μm formed on each sample. In Tests 1 to 2, the operator or the like confirmed the deposit S adhered to the transparent adhesive tape and evaluated it according to the following criteria. 〇: The deposit S is not adhered to the transparent adhesive tape (the deposit S has not peeled off from the first surface 11a). ×: The deposit S is adhered to the transparent adhesive tape (the deposit S has peeled off from the first surface 11a).

[0045] In Test 3, the operator or the like visually observed whether or not the deposit S having a thickness of 4.0 μm formed on each sample had peeled off from the first surface 11a. In Test 4, the operator or the like visually observed whether or not the deposit S having a thickness of 7.0 μm formed on each sample had peeled off from the first surface 11a. In Tests 3 to 4, the operator or the like evaluated according to the following criteria. 〇: The deposit S has not peeled off from the first surface 11a. ×: The deposit S has peeled off from the first surface 11a. The evaluation results of Tests 1 to 4 in each sample of Examples 1 to 21 and Comparative Examples 1 to 6 are shown in FIGS. 5 and 6.

[0046] As shown in Figure 5, in Examples 1 to 21, in which the arithmetic mean height Sa of the first surface 11a of the substrate 11 is 0.10 μm or more and the maximum height Sz is 2.56 μm or more, good results were obtained in Tests 1 to 4. In Examples 1 to 21, the surface roughness of the first surface 11a is suitably large, which can enhance the anchoring effect of the sediment S on the first surface 11a. Therefore, in Examples 1 to 21, the adhesive strength between the first surface 11a and the sediment S can be increased, resulting in the good results described above.

[0047] In contrast, for Comparative Examples 1 to 3, in which the arithmetic mean height Sa of the first surface 11a was less than 0.10 μm and the maximum height Sz was less than 2.56 μm, good results were not obtained in Tests 1 to 2 and Test 4. In Comparative Examples 1 to 3, the roughness of the first surface 11a was too low, resulting in a small anchoring effect of the sediment S on the first surface 11a. Therefore, in Comparative Examples 1 to 3, the adhesive strength between the first surface 11a and the sediment S was low, causing the sediment S to easily peel off the first surface 11a, and thus good results were not obtained as described above.

[0048] In Comparative Examples 4 to 6, where the arithmetic mean height Sa of the first surface 11a was 0.10 μm or more, but the maximum height Sz was less than 2.56 μm, good results were not obtained in Tests 1 to 2 and Test 4. In Comparative Examples 4 to 6, the maximum height Sz of the first surface 11a was too small, resulting in an excessively small anchoring effect of the sediment S on the first surface 11a. Consequently, in Comparative Examples 4 to 6, the adhesive strength between the first surface 11a and the sediment S was low, making it easy for the sediment S to peel off the first surface 11a, and thus good results were not obtained as described above.

[0049] For Examples 1 to 21, in which the difference between the maximum height Sz and the arithmetic mean height Sa was 2.46 μm or more, good results were obtained in Tests 1 to 4. This is because, even if the arithmetic mean height Sa of the first surface 11a is small, it is possible to suppress the maximum height Sz of the first surface 11a from becoming too small, thereby enhancing the anchoring effect of the sediment S on the first surface 11a.

[0050] The arithmetic mean curvature Spc of the peak of the first surface 11a of the substrate 11 is 1848.21 mm.－１ In the above-described Examples 1 to 21, favorable results were obtained in Tests 1 to 4. This is because the radius of curvature of the peaks of the ridges on the first surface 11a can be suitably reduced, thereby more favorably enhancing the anchoring effect of the sediment S on the first surface 11a.

[0051] For Examples 1 to 21, in which the developed area ratio Sdr of the interface of the first surface 11a of the substrate 11 is 0.05 or higher, good results were obtained in Tests 1 to 4. This is because it is possible to suppress the gap between the peaks of the first surface 11a from becoming too large, thereby more favorably enhancing the anchoring effect of the deposit S on the first surface 11a.

[0052] As shown in Figure 6, in Examples 1 to 21, where the arithmetic mean roughness Ra of the first surface 11a of the substrate 11 is 0.08 μm or more and the maximum height roughness Rz is 0.85 μm or more, good results were obtained in Tests 1 to 4. In Examples 1 to 21, the surface roughness of the first surface 11a is suitably large, which enhances the anchoring effect of the sediment S on the first surface 11a. Therefore, in Examples 1 to 21, the adhesive strength between the first surface 11a and the sediment S can be increased, resulting in the good results described above.

[0053] In contrast, for Comparative Examples 1 to 3, in which the maximum height roughness Rz of the first surface 11a was less than 0.85 μm, good results were not obtained in Tests 1 to 2 and Test 4. In Comparative Examples 1 to 3, the maximum height roughness Rz of the first surface 11a was too small, resulting in an excessively small anchoring effect of the sediment S on the first surface 11a. Therefore, in Comparative Examples 1 to 3, the adhesive strength between the first surface 11a and the sediment S was low, and as described above, good results were not obtained.

[0054] In Comparative Examples 4 to 6, although the arithmetic mean roughness Ra of the first surface 11a was 0.08 μm or more, the maximum height roughness Rz was less than 0.85 μm, and therefore good results were not obtained in Tests 1 to 2 and Test 4. In Comparative Examples 4 to 6, the maximum height roughness Rz of the first surface 11a was too small, resulting in an excessively small anchoring effect of the sediment S on the first surface 11a. Consequently, in Comparative Examples 4 to 6, the adhesive strength between the first surface 11a and the sediment S was low, and as described above, good results were not obtained.

[0055] According to this embodiment, the metal mask 10 is used when forming the internal electrodes 28 of a multilayer ceramic capacitor. The metal mask has through holes 12 formed in a metal substrate 11, and the arithmetic mean height Sa of the first surface 11a of the substrate 11, i.e., at least one surface of the substrate 11, is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more. As described above, when forming the internal electrodes 28, some of the nickel atoms that fly toward the green sheet 26 adhere to the first surface 11a of the metal mask 10. Therefore, if one metal mask 10 is used repeatedly to form the internal electrodes 28, the deposit S accumulated on the first surface 11a becomes thicker. If the thickness of the deposit S becomes too thick, as described above, the deposit S may peel off from the first surface 11a and float around inside the sputtering apparatus 20 shown in Figure 2. If the internal electrodes 28 are formed while the deposit S covers the surface of the green sheet 26, there is a risk that voids may be formed inside the internal electrodes 28. Furthermore, if the detached deposit S falls onto the target 23, there is a risk that the target 23, which is the cathode, will short-circuit with a grounded frame (not shown), causing the sputtering apparatus 20 to stop. To prevent this, when using one metal mask 10 repeatedly, it is necessary to periodically clean the first surface 11a to remove the deposit from the first surface 11a. In contrast, in this embodiment, as described above, the surface roughness of the first surface 11a can be suitably increased, thereby enhancing the anchoring effect of the deposit S on the first surface 11a. As a result, as described above, the adhesive strength between the first surface 11a and the deposit S can be increased, thus suitably suppressing the detachment of the deposit S from the first surface 11a when forming the internal electrode 28. Therefore, the frequency of cleaning the first surface 11a can be reduced, thereby increasing the productivity of the internal electrode 28.

[0056] Furthermore, in this embodiment, as described above, when forming the internal electrode 28, the deposition S peels off from the first surface 11a, which can suppress the formation of voids within the internal electrode 28 and also suppress the stopping of the sputtering apparatus 20. Therefore, the shape of the internal electrode 28 can be suitably stabilized, and an internal electrode 28 with good accuracy in MLCC superposition can be obtained.

[0057] According to this embodiment, the difference between the maximum height Sz and the arithmetic mean height Sa of the first surface 11a of the substrate 11, that is, at least one surface of the substrate 11, is 2.46 μm or more. Therefore, even if the arithmetic mean height Sa of the first surface 11a is small, it is possible to prevent the maximum height Sz of the first surface 11a from becoming too small. As a result, it is possible to suitably prevent the surface roughness of the first surface 11a from becoming too small, and thus prevent a decrease in the adhesive strength between the first surface 11a and the deposit S. Therefore, the frequency of cleaning the first surface 11a can be reduced, and the productivity of the internal electrode 28 can be increased.

[0058] According to this embodiment, the arithmetic mean curvature Spc of the first surface 11a of the base material 11, that is, the peak of at least one surface of the base material 11, is 1848.21 mm. －１ This concludes the explanation. Therefore, as described above, the radius of curvature of the peaks of the first surface 11a can be suitably reduced. This allows for a more favorable enhancement of the anchoring effect of the sediment S on the first surface 11a. Consequently, the adhesive strength between the first surface 11a and the sediment S can be more favorably increased. This allows for a more favorable reduction in the frequency of cleaning the first surface 11a, thereby more favorably increasing the productivity of the internal electrode 28.

[0059] According to this embodiment, the Sdr of the unfolded area ratio of the interface of the first surface 11a of the substrate 11, that is, at least one surface of the substrate 11, is 0.05 or more. Therefore, as described above, it is possible to suppress the gap between the peaks of the first surface 11a from becoming too large. As a result, the anchoring effect of the deposit S on the first surface 11a can be more effectively enhanced. Consequently, the adhesive strength between the first surface 11a and the deposit S can be more effectively enhanced. This allows for a more effectively reduced frequency of cleaning the first surface 11a, thereby more effectively increasing the productivity of the internal electrode 28.

[0060] According to this embodiment, the metal mask 10 is used when forming the internal electrodes 28 of a multilayer ceramic capacitor. The metal mask 10 has through holes 12 formed in a metal substrate 11, and the arithmetic mean roughness Ra of the first surface 11a of the substrate 11, i.e., at least one surface of the substrate 11, is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more. Therefore, as described above, the surface roughness of the first surface 11a can be suitably increased, and the anchoring effect of the deposit S on the first surface 11a can be suitably enhanced. As a result, the adhesive strength between the first surface 11a and the deposit S can be suitably increased, and the peeling of the deposit S from the first surface 11a can be suitably suppressed. Therefore, the frequency of cleaning the first surface 11a can be suitably reduced, and the productivity of the internal electrodes 28 can be suitably increased.

[0061] According to this embodiment, the difference between the maximum height roughness Rz and the arithmetic mean roughness Ra of the first surface 11a of the substrate 11, that is, at least one surface of the substrate 11, is 0.76 μm or more. Therefore, even if the arithmetic mean roughness Ra of the first surface 11a is small, it is possible to prevent the maximum height roughness Rz of the first surface 11a from becoming too small. As a result, it is possible to suitably prevent the surface roughness of the first surface 11a from becoming too small, and thus prevent a decrease in the adhesive strength between the first surface 11a and the deposit S. Therefore, the frequency of cleaning the first surface 11a can be reduced, and the productivity of the internal electrode 28 can be increased.

[0062] According to this embodiment, the manufacturing method Pm for the metal mask 10 is used when forming the internal electrodes 28 of a multilayer ceramic capacitor. The manufacturing method Pm for the metal mask 10 is a metal substrate 11 in which through holes 12 are formed, wherein the arithmetic mean height Sa of the first surface 11a of the substrate 11, i.e., at least one surface of the substrate 11, is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more. As a result, the surface roughness of the first surface 11a can be suitably increased, and the anchoring effect of the deposit S on the first surface 11a can be suitably enhanced. This increases the adhesive strength between the first surface 11a and the deposit S, and thus effectively suppresses the peeling of the deposit S from the first surface 11a when forming the internal electrodes 28. Therefore, the frequency of cleaning the first surface 11a can be reduced, and the productivity of the internal electrodes 28 can be increased.

[0063] According to this embodiment, the manufacturing method Pm for the metal mask 10 is to set the arithmetic mean roughness Ra of the first surface 11a of the substrate 11, that is, at least one surface of the substrate 11, to 0.08 μm or more, and the maximum height roughness Rz to 0.85 μm or more. As a result, as described above, the surface roughness of the first surface 11a can be suitably increased, and the anchoring effect of the deposit S on the first surface 11a can be suitably enhanced. This can suitably increase the adhesive strength between the first surface 11a and the deposit S, and thus suitably suppress the peeling of the deposit S from the first surface 11a. Therefore, the frequency of cleaning the first surface 11a can be suitably reduced, and the productivity of the internal electrode 28 can be suitably increased.

[0064] According to this embodiment, the substrate 11 is a metallic substrate 11 that constitutes a metal mask 10 used when forming the internal electrodes 28 of a multilayer ceramic capacitor, wherein the arithmetic mean height Sa of the first surface 11a, that is, at least one surface, is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more. Therefore, as described above, the surface roughness of the first surface 11a can be suitably increased, and the adhesive strength between the first surface 11a and the deposit S can be increased. Consequently, when forming the internal electrodes 28, the peeling of the deposit S from the first surface 11a can be suitably suppressed, and the frequency of cleaning the first surface 11a can be reduced.

[0065] According to this embodiment, the difference between the maximum height Sz and the arithmetic mean height Sa of the first surface 11a, that is, at least one of the surfaces, is 2.46 μm or more. Therefore, as described above, even when the arithmetic mean height Sa of the first surface 11a is small, it is possible to prevent the maximum height Sz of the first surface 11a from becoming too small. As a result, it is possible to suitably prevent the surface roughness of the first surface 11a from becoming too small, and thus prevent a decrease in the adhesive strength between the first surface 11a and the deposit S. Consequently, the frequency of cleaning the first surface 11a can be reduced.

[0066] According to this embodiment, the arithmetic mean curvature Spc of the first surface 11a, that is, the peak of at least one of the surfaces, is 1848.21 mm. －１ This concludes the explanation. Therefore, as described above, the radius of curvature of the peaks of the first surface 11a can be suitably reduced, which allows for a more favorable increase in the adhesive strength between the first surface 11a and the sediment S. This allows for a more favorable reduction in the frequency of cleaning the first surface 11a.

[0067] According to this embodiment, the developed area ratio Sdr of the interface of the first surface 11a, that is, at least one of the surfaces, is 0.05 or more. Therefore, as described above, it is possible to suppress the gap between the peaks of the first surface 11a from becoming too large, and thus the adhesive strength between the first surface 11a and the deposit S can be more favorably increased. As a result, the frequency of cleaning the first surface 11a can be more favorably reduced.

[0068] According to this embodiment, the substrate 11 is a metallic substrate 11 that constitutes a metal mask 10 used when forming the internal electrodes 28 of a multilayer ceramic capacitor, wherein the arithmetic mean roughness Ra of the first surface 11a, that is, at least one surface, is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more. Therefore, as described above, the surface roughness of the first surface 11a can be suitably increased, thereby increasing the adhesive strength between the first surface 11a and the deposit S. Consequently, when forming the internal electrodes 28, the peeling of the deposit S from the first surface 11a can be suitably suppressed, thereby reducing the frequency of cleaning the first surface 11a.

[0069] According to this embodiment, the difference between the maximum height roughness Rz and the arithmetic mean roughness Ra of the first surface 11a, that is, at least one of the surfaces, is 0.76 μm or more. Therefore, as described above, even when the arithmetic mean roughness Ra of the first surface 11a is small, it is possible to suppress the maximum height roughness Rz of the first surface 11a from becoming too small. As a result, it is possible to suitably suppress the surface roughness of the first surface 11a from becoming too small, and thus suppress the decrease in adhesive strength between the first surface 11a and the deposit S. Consequently, the frequency of cleaning the first surface 11a can be reduced.

[0070] Although the present invention has been described above, the specific configurations of the metal mask, the method for manufacturing the metal mask, and the substrate are not limited to these embodiments, and modifications and combinations of configurations that do not depart from the spirit of the present invention are also included.

[0071] The material constituting the metal mask according to the present invention is not limited to magnetic stainless steel such as SUS430. The material constituting the metal mask may be other magnetic metallic materials such as Invar and SuperInvar. Furthermore, as described above, if the base material can be fixed by a method other than magnetic attraction, the base material may be non-magnetic stainless steel such as SUS304.

[0072] The configuration of the metal mask according to the present invention is not limited to this embodiment. For example, the shape of the through holes, the number of through holes, the pitch of the through holes in the longitudinal direction, and the pitch of the through holes in the short direction may differ from those of this embodiment.

[0073] The method for manufacturing a metal mask according to the present invention is not limited to this embodiment. For example, the second thin-film thinning step may be performed before the first thin-film thinning step, or the first thin-film thinning step and the second thin-film thinning step may be performed simultaneously if the processing conditions are met.

[0074] The metal mask according to the present invention can be used as a mask when forming the internal electrodes of a multilayer ceramic capacitor. The method for manufacturing the metal mask according to the present invention can be used as a method for manufacturing the mask when forming the internal electrodes of a multilayer ceramic capacitor. The substrate according to the present invention can be used as a substrate for constituting the mask when forming the internal electrodes of a multilayer ceramic capacitor.

[0075] 10 Metal mask 11 Substrate 11a First surface (one side) 12 Through hole 28 Internal electrode Ra Arithmetic mean roughness Rz Maximum height roughness Sa Arithmetic mean height Sdr Interfacial development area ratio Spc Arithmetic mean curvature of peak Sz Maximum height

Claims

1. A metal mask used when forming internal electrodes of a multilayer ceramic capacitor, wherein through holes are formed in a metal substrate, and the arithmetic mean height Sa of at least one surface of the substrate is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more.

2. The metal mask according to claim 1, wherein the difference between the maximum height Sz and the arithmetic mean height Sa of one of the surfaces is 2.46 μm or more.

3. The arithmetic mean curvature Spc of the peak of one of the aforementioned faces is 1848.21 mm. －１ The metal mask according to claim 1 or 2.

4. The metal mask according to claim 1 or 2, wherein the developed area ratio Sdr of the interface of one of the surfaces is 0.05 or more.

5. A method for manufacturing a metal mask used when forming internal electrodes of a multilayer ceramic capacitor, wherein the metal mask has through holes formed in it, and the arithmetic mean height Sa of at least one surface of the metal mask is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more.

6. A metal mask used when forming internal electrodes of a multilayer ceramic capacitor, wherein through holes are formed in a metal substrate, and the arithmetic mean roughness Ra of at least one surface of the substrate is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more.

7. The metal mask according to claim 6, wherein the difference between the maximum height roughness Rz and the arithmetic mean roughness Ra of one of the surfaces is 0.76 μm or more.

8. A method for manufacturing a metal mask used when forming internal electrodes of a multilayer ceramic capacitor, wherein a metal substrate has through holes formed in it, the arithmetic mean roughness Ra of at least one surface of the substrate is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more.

9. A metal substrate that constitutes a metal mask used when forming the internal electrodes of a multilayer ceramic capacitor, wherein the arithmetic mean height Sa of at least one surface is 0.10 μm or more, and the maximum height Sz is 2.56 μm or more.

10. The substrate according to claim 9, wherein the difference between the maximum height Sz and the arithmetic mean height Sa of one of the surfaces is 2.46 μm or more.

11. The arithmetic mean curvature Spc of the peak of one of the aforementioned faces is 1848.21 mm. －１ The substrate according to claim 9 or 10.

12. The substrate according to claim 9 or 10, wherein the developed area ratio Sdr of the interface of one of the surfaces is 0.05 or more.

13. A metal substrate that constitutes a metal mask used when forming the internal electrodes of a multilayer ceramic capacitor, wherein the arithmetic mean roughness Ra of at least one surface is 0.08 μm or more, and the maximum height roughness Rz is 0.85 μm or more.

14. The substrate according to claim 13, wherein the difference between the maximum height roughness Rz and the arithmetic mean roughness Ra of one of the surfaces is 0.76 μm or more.

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