Metal mask and method for manufacturing metal mask

Abstract

The purpose of this invention is to provide a metal shield that can maintain strength and is not prone to shading, and a method for manufacturing the same. A metal shield has a first surface and a second surface located opposite the first surface. The first surface has a through hole, a first vertex portion, and a second vertex portion. The through hole includes a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole. The first through hole has a first minor axis and a first major axis. The second through hole has a second minor axis and a second major axis. The third through hole has a third minor axis and a third major axis. The fourth through hole has a fourth minor axis and a fourth major axis. The fifth through hole has a fifth minor axis and a fifth major axis. The sixth through hole has a sixth minor axis and a sixth major axis. The first major axis is parallel to the second major axis and is located next to the second major axis in a direction D2 that intersects the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and the height H1 of the first vertex is higher than the height H2 of the second vertex.

Description

Technical Field

[0001] The invention relates to a metal mask and a manufacturing method thereof. Prior Art

[0002] Pixels in organic EL (electroluminescence) displays are formed by depositing the pixel material onto a substrate using a metal mask. Therefore, improving the performance of the metal mask is crucial for enhancing the image quality of organic EL displays.

[0003] For example, Patent Document 1 discloses a method for manufacturing a metal mask capable of forming through holes with high precision. [Prior Art Literature] [Patent Document]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-163734 Summary of the Invention

[0005] [Problems to be solved by the invention]

[0006] The metal mask has, for example, an active area with through holes and a peripheral area around the active area. The metal mask is disposed on a frame and is used for evaporation of pixels.

[0007] During the evaporation step, the evaporation material moving from the evaporation source toward the metal mask moves in the thickness direction of the metal plate forming the metal mask. A portion of the evaporation material moves along the walls of the through-holes that define the metal plate, in a direction oblique to the thickness direction. This portion of the evaporation material that moves in a direction oblique to the thickness direction of the metal plate adheres to the through-hole walls rather than the substrate. Therefore, the evaporation layer formed on the substrate tends to become thinner near the through-hole walls. This phenomenon, in which the adhesion of the evaporation material to the substrate is hindered by the through-hole walls, is also called shading.

[0008] To reduce shading, one approach is to reduce the thickness of the metal plate that forms the metal mask. However, reducing the thickness of the metal plate reduces its strength. This can lead to other problems, such as the metal mask being easily deformed during the vapor deposition process.

[0009] The present invention is completed in view of the above-mentioned problems, and its purpose is to provide a metal mask that maintains strength and is not prone to shading, and a manufacturing method thereof. [Technical means to solve the problem]

[0010] A metal mask according to one embodiment of the present invention comprises a first surface and a second surface located on the opposite side of the first surface. The first surface has a through hole, a first vertex, and a second vertex. The through holes include a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole. The first through hole has a first minor axis and a first major axis, The second through hole has a second minor axis and a second major axis, The third through hole has a third minor axis and a third major axis. The fourth through hole has a fourth minor axis and a fourth major axis. The fifth through hole has a fifth minor axis and a fifth major axis. The sixth through hole has a sixth minor axis and a sixth major axis. The first major axis is parallel to the second major axis and is located next to the second major axis in a direction D2 that intersects the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 that is parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and The height H1 of the first vertex is higher than the height H2 of the second vertex.

[0011] The method for manufacturing the metal mask according to one embodiment of the present invention includes the following steps: Preparing a metal plate having a first surface and a second surface located on the opposite side of the first surface; and an etching step, wherein the metal mask is formed by etching the metal plate; The metal mask has a first surface and a second surface located on the opposite side of the first surface. The first surface has a through hole, a first vertex, and a second vertex. The through holes include a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole. The first through hole has a first minor axis and a first major axis, The second through hole has a second minor axis and a second major axis, The third through hole has a third minor axis and a third major axis. The fourth through hole has a fourth minor axis and a fourth major axis. The fifth through hole has a fifth minor axis and a fifth major axis. The sixth through hole has a sixth minor axis and a sixth major axis. The first major axis is parallel to the second major axis and is located next to the second major axis in a direction D2 that intersects the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 that is parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and The height H1 of the first vertex is higher than the height H2 of the second vertex. [Effects of the Invention]

[0012] In at least one embodiment of the present invention, a metal mask that maintains strength and is not prone to shading and a method for manufacturing the same are provided. Simple diagram description

[0013] FIG. 1 is a diagram showing a metal mask device including a metal mask according to an embodiment of the present invention. FIG2 is a cross-sectional view showing a vapor deposition device according to one embodiment of the present invention. FIG3 is a top view showing an example of a pattern of a vapor-deposited layer of an organic EL display device. FIG. 4 is a top view showing a metal mask according to an embodiment of the present invention. FIG5 is a perspective view of an effective area of ​​a metal mask according to an embodiment of the present invention as viewed from the second surface side. FIG6A is a top view of the effective area of ​​the metal mask according to one embodiment of the present invention as viewed from the second surface side. FIG6B is a top view of the effective area of ​​the metal mask according to one embodiment of the present invention, viewed from the second surface side. FIG7 is a cross-sectional view taken along line AA′ of FIG6A . FIG8 is a cross-sectional view taken along line BB′ of FIG6A . FIG9 is a cross-sectional view taken along line CC' of FIG6A. FIG. 10 is a schematic diagram for explaining an example of a method for manufacturing a metal mask. FIG. 11 is a diagram showing an example of the steps of forming a resist film on a metal plate. FIG. 12 is a diagram showing an example of a step of patterning a resist film. FIG13 is a diagram showing an example of the first surface etching step. FIG14 is a diagram showing an example of the second surface etching step. FIG15 is a diagram showing an example of the second surface etching step. Implementation Method

[0014] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Furthermore, in the drawings accompanying this specification, the scales and aspect ratios may be appropriately altered and enlarged compared to the actual objects for the sake of convenience and understanding.

[0015] Unless otherwise specified, in this specification and the accompanying drawings, an example of a metal mask and its manufacturing method used to pattern an organic material into a desired pattern on a substrate when manufacturing an organic EL display device is described in one embodiment. However, the present invention is not limited to this application and can be applied to metal masks for various purposes. For example, the metal mask of the present invention can be used to manufacture devices for displaying or projecting images or videos used to represent virtual reality (VR) or augmented reality (AR).

[0016] Unless otherwise specified in this specification and / or the drawings, the following interpretations shall apply.

[0017] Terms referring to the material that forms the basis of a structure can be distinguished not only by name. For example, terms such as "substrate," "base material," "board," "sheet," or "film" fall within the meaning of the above description.

[0018] Terms and / or numerical values ​​referring to shapes and / or geometric conditions are not necessarily strictly defined and can be interpreted as encompassing a range of conditions that can achieve the same function. For example, terms such as "parallel" and / or "orthogonal" fall within the meanings of these terms. Similarly, terms such as "length values" and / or "angle values" fall within the meanings of these numerical values.

[0019] When a component is expressed as being "above," "below," "upper," "lower," "above," or "below" another component, this includes both the component being directly in contact with the other component and the component being located between the other component. In other words, the presence of another component between the other component can also be expressed as the component being indirectly in contact with the other component. Furthermore, the expressions "above," "upper," or "above" can be interchanged with the expressions "lower," "lower," or "below." In other words, the up-down direction can be reversed.

[0020] When identical components and / or components having identical functions are denoted by identical or similar symbols, duplicate descriptions may be omitted. Furthermore, the dimensional ratios in the drawings may differ from the actual ratios. Furthermore, portions of the components of the embodiments may be omitted from the drawings.

[0021] It is also possible to combine one or more aspects of the embodiment with one or more aspects of the variation within the scope that no contradiction occurs. Furthermore, it is also possible to combine one or more aspects of the embodiment with each other within the scope that no contradiction occurs. Furthermore, it is also possible to combine one or more aspects of the variation with each other within the scope that no contradiction occurs.

[0022] When a method such as a manufacturing method discloses multiple steps, other steps not disclosed may be performed between the disclosed steps. Furthermore, the order of the steps is not limited to the extent that no contradiction arises.

[0023] Numerical ranges expressed with "~" and / or "-" include values ​​before and after the "~" and / or "-" symbols. For example, a numerical range expressed as "34-38 mass %" is the same as a numerical range expressed as "34 mass % or more and 38 mass % or less."

[0024] Regarding the numerical values ​​described in the present invention, a numerical range can be defined by combining any one of a plurality of candidate upper limit values ​​with any one of a plurality of candidate lower limit values. Furthermore, even if not specifically mentioned, a numerical range can be defined by combining any two of a plurality of candidate upper limit values, or by combining any two of a plurality of candidate lower limit values.

[0025] One embodiment of the present invention is described in the following paragraphs and the following paragraphs. One embodiment of the present invention is an example of an embodiment of the present invention. The present invention is not limited to the one embodiment of the present invention.

[0026] The first aspect of the present invention is a metal mask having a first surface and a second surface located on the opposite side of the first surface. The first surface has a through hole, a first vertex, and a second vertex. The through holes include a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole. The first through hole has a first minor axis and a first major axis, The second through hole has a second minor axis and a second major axis, The third through hole has a third minor axis and a third major axis. The fourth through hole has a fourth minor axis and a fourth major axis. The fifth through hole has a fifth minor axis and a fifth major axis. The sixth through hole has a sixth minor axis and a sixth major axis. The first major axis is parallel to the second major axis and is located next to the second major axis in a direction D2 that intersects the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 that is parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and The height H1 of the first vertex is higher than the height H2 of the second vertex.

[0027] The second aspect of the present invention is the metal mask of the first aspect, wherein the metal mask may be: In a direction D3 passing through the first vertex and the second vertex, the first vertex and the second vertex exist alternately.

[0028] The third aspect of the present invention is the metal mask of the first aspect or the second aspect, wherein the metal mask may be: The acute angle formed by the direction D1 and the direction D3 is greater than or equal to 30° and less than or equal to 60°.

[0029] The fourth aspect of the present invention is a metal mask as described in any one of the first to third aspects, wherein the metal mask may be: The height H1 is not less than 0.60 times and not more than 1.00 times the height T from the first surface to the second surface.

[0030] The fifth aspect of the present invention is a metal mask as described in any one of the first to fourth aspects, wherein the metal mask may be: The height H2 is not less than 0.30 times and not more than 0.95 times the height T from the first surface to the second surface.

[0031] The sixth aspect of the present invention is a metal mask as described in any one of the first to fifth aspects, wherein the metal mask may be: The height H2 of the second vertex is not more than 0.90 times the height H1 of the first vertex.

[0032] The seventh aspect of the present invention is a metal mask as described in any one of the first to sixth aspects, wherein the metal mask may be: The through hole has a first recess located on the first surface side, a second recess located on the second surface side, a connecting portion, a first angle θ1, and a second angle θ2, The connecting portion is a ridge connecting the first concave portion and the second concave portion. The first angle θ1 is the angle formed by a straight line K1 passing through the portion P1a of the connecting portion closest to the first vertex and the portion P2a of the first vertex closest to the connecting portion relative to the thickness direction N of the metal mask. The second angle θ2 is the angle formed by a straight line K2 passing through the portion P1b of the connecting portion closest to the second vertex portion and the portion P2b of the second vertex portion closest to the connecting portion relative to the thickness direction N of the metal mask, and The first angle θ1 and the second angle θ2 have a relationship of θ2≧θ1.

[0033] The eighth aspect of the present invention is a metal mask as in any one of the first to seventh aspects, wherein the metal mask may be: The radius of curvature of the second vertex is not less than 2.0 μm and not more than 18 μm.

[0034] The ninth aspect of the present invention is a metal mask as described in any one of the first to eighth aspects, wherein The opening shape of the through hole may also be substantially rectangular or substantially elliptical.

[0035] A tenth aspect of the present invention is a method for manufacturing a metal mask, which is a method for manufacturing a metal mask according to any one of the first to ninth aspects, and includes the following steps: Preparing a metal plate having a first surface and a second surface located on the opposite side of the first surface; and an etching step, wherein the metal mask is formed by etching the metal plate; The metal mask has a first surface and a second surface located on the opposite side of the first surface. The first surface has a through hole, a first vertex, and a second vertex. The through holes include a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole. The first through hole has a first minor axis and a first major axis, The second through hole has a second minor axis and a second major axis, The third through hole has a third minor axis and a third major axis. The fourth through hole has a fourth minor axis and a fourth major axis. The fifth through hole has a fifth minor axis and a fifth major axis. The sixth through hole has a sixth minor axis and a sixth major axis. The first major axis is parallel to the second major axis and is located next to the second major axis in a direction D2 that intersects the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 that is parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and The height H1 of the first vertex is higher than the height H2 of the second vertex.

[0036] First, an example of a vapor deposition apparatus equipped with a metal mask will be described with reference to Figures 1 and 2. Figure 1 is a top view of a metal mask apparatus 10 equipped with a metal mask 20 according to an embodiment of the present invention, as viewed from the first surface 20a of the metal mask 20. Figure 2 is a cross-sectional view of the vapor deposition apparatus.

[0037] As shown in FIG1 , each metal mask 20 may have a generally rectangular shape extending in one direction. Furthermore, the metal mask device 10 may include a plurality of metal masks 20 formed of generally rectangular metal plates, and a frame 15 attached to the periphery of the plurality of metal masks 20. Furthermore, the plurality of metal masks 20 may be arranged along a width direction intersecting the longitudinal direction of the metal masks 20. Furthermore, each metal mask 20 may be fixed to the frame 15 at both ends of the metal mask 20 in the longitudinal direction, for example, by welding.

[0038] The metal mask device 10 may include a member fixed to the frame 15 and partially overlapping the metal mask 20 in the thickness direction of the metal mask 20. Examples of such a member are not particularly limited, and include a member extending in a direction intersecting the longitudinal direction of the metal mask 20 and supporting the metal mask 20, and a member overlapping the gap between two adjacent metal masks.

[0039] As shown in FIG2 , the metal mask device 10 is supported within the evaporation apparatus 90 so as to face a substrate 92. Here, the substrate 92 is a glass substrate, for example, on which the metal mask 20 is to be deposited. When the metal mask device 10 is housed within the evaporation apparatus 90 as shown in FIG2 , the surface of the metal mask 20 facing the substrate 92 is referred to as the first surface 20 a, and the surface of the metal mask 20 facing the crucible 94 holding the evaporation material 98 is referred to as the second surface 20 b.

[0040] In the evaporation device 90, a metal mask 20 is disposed on the crucible 94 side of the substrate 92. Here, the metal mask 20 and the substrate 92 can also be in close contact with each other by magnetic force.

[0041] A crucible 94 containing a deposition material 98 and a heater 96 for heating the crucible 94 can also be arranged below the metal mask device 10 within the deposition apparatus 90. For example, the deposition material 98 can be an organic light-emitting material. Heat from the heater 96 vaporizes or sublimates the deposition material 98 within the crucible 94. The vaporized or sublimated deposition material 98 adheres to the substrate 92 through the through-holes 25 of the metal mask 20. Consequently, the deposition material 98 is deposited on the surface of the substrate 92 in a desired pattern corresponding to the positions of the through-holes 25 of the metal mask 20.

[0042] To deposit different types of deposition materials for pixels such as RGB, different metal masks 20 can be used according to the color of the organic light-emitting material to form a film of deposition material 98 on the surface of substrate 92. For example, a red organic light-emitting material, a green organic light-emitting material, and a blue organic light-emitting material can be sequentially deposited on substrate 92. Alternatively, the metal mask 20 (metal mask device 10) and substrate 92 can be relatively moved bit by bit along the direction of arrangement of the through-holes 25 (one of the aforementioned directions) to sequentially deposit the red organic light-emitting material, the green organic light-emitting material, and the blue organic light-emitting material.

[0043] Figure 3 shows a top view of an example pattern of an evaporated layer in an organic EL display device. As shown in Figure 3, in the pattern of the evaporated layers, the first evaporated layer 99A includes four sides having a size M1. The third evaporated layer 99C may include four sides having a size M2 that is smaller than size M1. The second evaporated layer 99B may include a pair of sides having a size M3 and a pair of sides having a size M4 that is smaller than size M3. Furthermore, the sides of the second evaporated layer 99B having a size M3 may face the sides of the first evaporated layer 99A in the first direction D1 or the second direction D2. The sides of the second evaporated layer 99B having a size M4 may face the sides of the third evaporated layer 99C in the first direction D1 or the second direction D2. Dimension M3 may be the same as dimension M1. Dimension M4 may be the same as dimension M2.

[0044] Here, the second vapor-deposited layer 99B can also be formed using a metal mask 20. As shown in Figures 6A and 6B below, the metal mask 20 has a through hole including a major axis 26 and a minor axis 27 of different lengths. Furthermore, the first vapor-deposited layer 99A, the second vapor-deposited layer 99B, and the third vapor-deposited layer 99C can also be assigned any of the RGB colors, for example.

[0045] Furthermore, the frame 15 of the metal mask device 10 can also be mounted on the periphery of the rectangular metal mask 20. The frame 15 holds the metal mask 20 in a stretched state. The metal mask 20 and the frame 15 can also be fixed to each other by, for example, spot welding.

[0046] 1 shows an example in which a plurality of long metal shields 20 are provided on the frame 15. Alternatively, a large metal shield 20 having a shape substantially the same as that of the frame 15 may be provided on the frame 15.

[0047] The following describes the metal mask of the present invention in detail, using a metal mask used for vapor deposition of organic light-emitting materials for organic EL displays as an example. However, the metal mask of the present invention is not limited to vapor deposition of organic light-emitting materials for organic EL displays and can also be used to manufacture devices for displaying or projecting images or videos used to express virtual reality (VR) or augmented reality (AR).

[0048] The metal mask of the present invention has a first surface and a second surface located on the opposite side of the first surface. The first surface has a through hole, a first vertex, and a second vertex. The through holes include a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole. The first through hole has a first minor axis and a first major axis, The second through hole has a second minor axis and a second major axis, The third through hole has a third minor axis and a third major axis. The fourth through hole has a fourth minor axis and a fourth major axis. The fifth through hole has a fifth minor axis and a fifth major axis. The sixth through hole has a sixth minor axis and a sixth major axis. The first major axis is parallel to the second major axis and is located next to the second major axis in a direction D2 that intersects the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 that is parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and The height H1 of the first vertex is higher than the height H2 of the second vertex.

[0049] FIG4 shows a top view of a metal mask 20 according to one embodiment of the present invention. The metal mask 20 can be obtained by etching through-holes 25 in a metal plate 51. As shown in FIG4 , the metal mask 20 can have an active area 22 in which the through-holes 25 are arranged, and a peripheral area 23 surrounding the active area 22. The metal mask 20 can have a generally rectangular outline when viewed from above.

[0050] The height T from the first surface to the second surface is preferably 50 μm or less, and may be 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, or 13 μm or less. Reducing the height T can suppress shading.

[0051] Furthermore, the height T is preferably greater than 2 μm, and may be greater than 5 μm, 10 μm, or 15 μm. Increasing the height T tends to further enhance the strength of the metal mask 20 . This can prevent deformation or cracking of the active area 22 , for example.

[0052] Furthermore, the range of height T can also be defined by a combination of any one of the plurality of candidate lower limit values ​​and any one of the plurality of candidate upper limit values. Furthermore, height T is the thickness of the portion of the metal mask 20 where the first recess 30 and the second recess 35 are not formed. In other words, height T can also be equal to the thickness of the surrounding area 23 or the thickness of the metal plate 51 of the metal mask 20.

[0053] The coefficient of thermal expansion of the metal mask 20 is preferably the same as that of the frame 15 or the substrate 92. This prevents positional deviations caused by dimensional variations among the metal mask 20, frame 15, and substrate 92 during the deposition process performed in a high-temperature environment. Consequently, it prevents a decrease in the dimensional accuracy or positional accuracy of the deposition material 98 deposited on the substrate 92 due to positional deviations.

[0054] For example, when a glass substrate is used as the substrate 92, a nickel-containing iron alloy can be used as the main material for the metal mask 20 and the frame 15. Examples of nickel-containing iron alloys include those containing 30% to 54% nickel by mass. More specifically, such iron alloys include Invar alloys containing 34% to 38% nickel by mass, Super Invar alloys containing 30% to 34% nickel and cobalt, and low thermal expansion Fe-Ni plating alloys containing 48% to 54% nickel by mass.

[0055] Furthermore, when the temperatures of the metal mask 20, frame 15, and substrate 92 do not reach high temperatures during the vapor deposition process, it is not particularly necessary to set the thermal expansion coefficients of the metal mask 20 and frame 15 to the same value as the thermal expansion coefficient of the substrate 92. In this case, the material for the metal plate 51 below constituting the metal mask 20, in addition to the nickel-containing iron alloy described above, can include chromium-containing iron alloys such as stainless steel, nickel, or nickel-cobalt alloys.

[0056] The metal mask 20 may have a plurality of active areas 22. For example, as shown in FIG4 , the metal mask 20 may have a plurality of active areas 22 arranged in a row at predetermined intervals along a direction parallel to its length. This type of metal mask 20 is sometimes referred to as a rod-shaped metal mask. In this case, as shown in FIG1 , the metal mask device 10 may have a plurality of metal masks 20 arranged in a width direction perpendicular to its length and mounted on the frame 15.

[0057] As another example, the metal mask 20 may have a plurality of active areas 22 arranged at specific intervals along a direction parallel to a side of the metal mask 20, and a plurality of active areas 22 arranged at specific intervals along another direction perpendicular to the aforementioned direction. In other words, the metal mask 20 may also have a plurality of rows of active areas 22. In this case, the metal mask device 10 may also mount a metal mask 20 of a size approximately the same as the frame 15 on the frame 15.

[0058] The active area 22 has a through hole 25, a first vertex 32a, and a second vertex 32b on the first surface. The active area 22 may also be a region that faces the region on the substrate 92 where the organic light-emitting material is vapor-deposited to form pixels, and functions as a mask during vapor deposition.

[0059] The metal mask 20 can have multiple active areas 22. One active area 22 can also be configured to correspond to the display area of ​​a single organic EL display device 100. Using this metal mask device 10, multi-surface vapor deposition can be performed on an organic EL display device. Furthermore, one active area 22 can also be configured to correspond to the display areas of multiple organic EL display devices.

[0060] The active area 22 may have a substantially rectangular outline in a plan view. Furthermore, the active area 22 may also have various shapes such as a circular outline depending on the shape of the display area of ​​the substrate 92 .

[0061] FIG5 shows a perspective view of the active area 22 as viewed from the second surface 20b as one embodiment of the present invention. The active area 22 may have through-holes 25 formed by etching. As shown in FIG5 , the plurality of through-holes 25 formed in each active area 22 are arranged in a specific pattern. For example, when viewed from the second surface 20b, the through-holes 25 may be arranged at specific intervals along the intersecting first direction D1 and second direction D2. Furthermore, a plurality of first vertices 32a, a plurality of second vertices 32b, and a plurality of ridges 33 may be located around the through-holes 25. Adjacent second recesses 35 may also be connected by ridges 33.

[0062] As shown in Figure 5 , ridgeline 33 refers to the boundary formed by the confluence of the second wall surfaces 36 of adjacent second recesses 35. The height of ridgeline 33 may not be constant, but may fluctuate like a wave. Furthermore, the height of ridgeline 33 can also be described as the position of ridgeline 33 in the thickness direction of metal mask 20. Generally speaking, the height of ridgeline 33 varies depending on the distance from the center of through-hole 25, with the longer the distance, the higher the height.

[0063] 6A and 6B show partial top views of the effective area 22 of the metal mask 20 as viewed from the second surface 20b. In the present invention, the through-holes 25 include at least a first through-hole 25a, a second through-hole 25b, a third through-hole 25c, a fourth through-hole 25d, a fifth through-hole 25e, and a sixth through-hole 25f.

[0064] Furthermore, when there is no need to distinguish the first through-hole 25a, the second through-hole 25b, the third through-hole 25c, the fourth through-hole 25d, the fifth through-hole 25e, and the sixth through-hole 25f, they are simply referred to as "through-hole 25." Similarly, when there is no need to distinguish the major axis of these through-holes, they are simply referred to as "major axis 26." Furthermore, when there is no need to distinguish the minor axis of these through-holes, they are simply referred to as "minor axis 27."

[0065] Furthermore, as shown in FIG8 , for example, the dimensions of the major axes 26a, b, and e of through-holes 25a, b, and e refer to the distance between opposing connecting portions 41 in direction D1. Furthermore, as shown in FIG7 , for example, the dimensions of the minor axes 27a, b, and e of through-holes 25a, b, and e refer to the distance between opposing connecting portions 41 in direction D2. Similarly, the dimensions of the major axes 26c, d, and f of through-holes 25c, d, and f refer to the distance between opposing connecting portions 41 in direction D2. Furthermore, the dimensions of the minor axes 27c, d, and f of through-holes 25c, d, and f refer to the distance between opposing connecting portions 41 in direction D1. In other words, the major axis 26 and minor axis 27 of a through-hole 25 can also refer to the distance in direction D1 or D2 at the portion where the through-hole opening area is minimized.

[0066] The first through-hole 25a has a first minor axis 27a and a first major axis 26a. The first major axis 26a is parallel to the second major axis 26b and is located adjacent to the second major axis 26b in a direction D2 intersecting the first major axis 26a. The first minor axis 27a is parallel to the fifth minor axis 27e and is located adjacent to the fifth minor axis 27e in a direction D1 parallel to the first major axis 26a. Alternatively, the first minor axis 27a may be parallel to the third major axis 26c and the fourth major axis 26d and not adjacent to the third major axis 26c and the fourth major axis 26d in the direction D1.

[0067] The second through-hole 25b has a second minor axis 27b and a second major axis 26b. The second major axis 26b is parallel to the first major axis 26a and is located adjacent to the first major axis 26a in direction D2. Alternatively, the second minor axis 27b may be parallel to the third major axis 26c and the fourth major axis 26d and not adjacent to the third major axis 26c and the fourth major axis 26d in direction D1.

[0068] The third through-hole 25c has a third minor axis 27c and a third major axis 26c. The third major axis 26c is parallel to the fourth major axis 26d and is located adjacent to the fourth major axis 26d in direction D1. The third minor axis 27c is parallel to the sixth minor axis 27f and is located adjacent to the sixth minor axis 27f in direction D2. Alternatively, the third minor axis 27c may be parallel to the first major axis 26a and the second major axis 26b and not adjacent to the first major axis 26a and the second major axis 26b in direction D2.

[0069] The fourth through-hole 25d has a fourth minor axis 27d and a fourth major axis 26d. The fourth major axis 26d is parallel to the third major axis 26c and is located adjacent to the third major axis 26c in direction D1. Alternatively, the fourth minor axis 27d may be parallel to the first major axis 26a and the second major axis 26b and not adjacent to the first major axis 26a and the second major axis 26b in direction D2.

[0070] The fifth through-hole 25e has a fifth minor axis 27e and a fifth major axis 26e. The fifth minor axis 27e is parallel to the first minor axis 27a and is located adjacent to the first minor axis 27a in direction D1. Alternatively, the fifth minor axis 27e may be parallel to the fourth major axis 26d and the sixth major axis 26f and not adjacent to the fourth major axis 26d and the sixth major axis 26f in direction D1.

[0071] The sixth through-hole 25f has a sixth minor axis 27f and a sixth major axis 26f. The sixth minor axis 27f is parallel to the third minor axis 27c and is located adjacent to the third minor axis 27c in direction D2. Alternatively, the sixth minor axis 27f may be parallel to the first major axis 26a and the fifth major axis 26e and not adjacent to the first major axis 26a and the fifth major axis 26e in direction D1.

[0072] As described above, the first through-hole 25a, the second through-hole 25b, and the fifth through-hole 25e have major axes 26 parallel to the direction D1. Furthermore, the third through-hole 25c, the fourth through-hole 25d, and the sixth through-hole 25f have major axes 26 parallel to the direction D2. This forms a first region R1 surrounded by the first major axis 26a, the second major axis 26b, the third major axis 26c, and the fourth major axis 26d. Furthermore, a second region R2 is formed, surrounded by the first minor axis 27a, the fifth minor axis 27e, the third minor axis 27c, and the sixth minor axis 27f.

[0073] The first vertex 32a is located between the first major axis 26a and the second major axis 26b, and between the third major axis 26c and the fourth major axis 26d. The first vertex 32a is located approximately at the center of the first region R1. Furthermore, the second vertex 32b is located between the first minor axis 27a and the fifth minor axis 27e, and between the third minor axis 27c and the sixth minor axis 27f. The second vertex 32b is located approximately at the center of the second region R2. The second region R2, surrounded by the minor axis 27, is narrower than the first region R1, surrounded by the major axis 26.

[0074] In the present invention, the height H1 of the first vertex 32a is higher than the height H2 of the second vertex 32b. The first vertex 32a and the second vertex 32b may also be the thickest portion in the first region R1 or the second region R2, respectively.

[0075] In Figure 5 , the first vertex 32a is shown as the portion remaining without etching, with the second surface 20b at its top. This vertex portion with a top that remains without etching is also referred to as a "rib." When the first vertex 32a is a rib, the height H1 of the first vertex 32a is approximately the same as the height T. Furthermore, since the second surface 20b remains without etching, the top of the rib is flat. Furthermore, the top of the rib, when viewed from above, may be roughly rectangular, for example.

[0076] 5 , the second vertex 32 b may be a portion of the ridge line 33 having the highest height in the second region R2 .

[0077] The first vertex 32a and the second vertex 32b are not limited to the above. For example, the first vertex 32a may be the portion of the ridgeline 33 where the height is the highest in the first region R1. In other words, the first vertex 32a may not be a rib. If the first vertex 32a is not a rib, the first vertex 32a and the second vertex 32b may also be the portions of the ridgeline 33 where the height is the highest.

[0078] The first and second apex portions 32a, 32b may be located at the intersection of multiple ridgelines 33 extending in different directions D3. Furthermore, the first and second apex portions 32a, 32b may alternate in the direction D3 passing through the first and second apex portions 32a, 32b. The direction D3 may also be the same as the direction in which the ridgelines between adjacent through-holes 25 extend. This tends to improve strength and further suppress shading.

[0079] The acute angle θ3 formed by directions D1 and D3 is preferably 30° or greater, more preferably 35° or greater, and even more preferably 40° or greater. Furthermore, the acute angle θ3 formed by directions D1 and D3 is preferably 60° or less, more preferably 55° or less, and even more preferably 50° or less. This tends to further improve strength and suppress shading.

[0080] By setting the angle θ3 within the above range, the intensity tends to be further improved, and the occurrence of shading tends to be further suppressed. Furthermore, the range of the angle θ3 can also be defined by combining any one of the plurality of candidate lower limit values ​​described above with any one of the plurality of candidate upper limit values ​​described above.

[0081] The height H1 of the first apex portion 32a is preferably 50 μm or less, and may be 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, or 13 μm or less. Furthermore, the height H1 of the first apex portion 32a is preferably 2 μm or more, and may be 5 μm or more, 10 μm or more, or 15 μm or more.

[0082] The height H1 of the first apex portion 32a is preferably 0.60 times or greater, and may be 0.65 times or greater, 0.70 times or greater, 0.75 times or greater, 0.80 times or greater, or 0.85 times or greater relative to the height T. Furthermore, the height H1 of the first apex portion 32a is preferably 1.00 times or less, and may be 0.95 times or less, 0.90 times or less, 0.85 times or less, or 0.80 times or less relative to the height T.

[0083] By reducing the height H1 of the first vertex 32a, shading tends to be further suppressed. Furthermore, by increasing the height H1 of the first vertex 32a, the strength of the metal mask 20 tends to be further improved. Furthermore, the range of the height H1 of the first vertex 32a can also be defined by a combination of any one of the plurality of candidate lower limit values ​​described above and any one of the plurality of candidate upper limit values ​​described above.

[0084] When the first vertex 32a is a rib, the second surface 20b remains unetched, so the top of the first vertex 32a is flat. In this case, the area of ​​the first vertex 32a when it is a rib is preferably 5 μm² or greater, and may be 15 μm² or greater, 25 μm² or greater, 35 μm² or greater, or 45 μm² or greater. Furthermore, the area of ​​the first vertex 32a is preferably 200 μm² or less, and may be 175 μm² or less, 150 μm² or less, 125 μm² or less, or 100 μm² or less.

[0085] By reducing the area of ​​the first vertex 32a, shading tends to be further suppressed. Furthermore, by increasing the area of ​​the first vertex 32a, the strength of the metal mask 20 tends to be further improved. Furthermore, the range of the height H1 of the first vertex 32a can also be defined by a combination of any one of the plurality of candidate lower limit values ​​described above and any one of the plurality of candidate upper limit values ​​described above.

[0086] The height H2 of the second apex portion 32b is preferably 6 μm or greater, and may be 7 μm or greater, 8 μm or greater, 9 μm or greater, 10 μm or greater, or 12 μm or greater. Furthermore, the height H2 of the second apex portion 32b is preferably 35 μm or less, and may be 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0087] The height H2 of the second apex portion 32b is preferably 0.30 times or greater, and may be 0.40 times or greater, 0.50 times or greater, 0.60 times or greater, or 0.70 times or greater, relative to the height T. Furthermore, the height H2 of the second apex portion 32b is preferably 0.95 times or less, and may be 0.90 times or less, 0.85 times or less, 0.70 times or less, 0.80 times or less, or 0.75 times or less relative to the height T.

[0088] Furthermore, the height H2 of the second apex portion 32b is preferably 0.50 times or greater, and may be 0.55 times or greater, 0.60 times or greater, 0.65 times or greater, or 0.70 times or greater, relative to the height H1 of the first apex portion 32a. Furthermore, the height H2 of the second apex portion 32b is preferably 0.95 times or less, and may be 0.90 times or less, 0.85 times or less, 0.80 times or less, 0.75 times or less, or 0.70 times or less, relative to the height H1 of the first apex portion 32a. Furthermore, the range of height H2 relative to height H1 can be any combination of the upper and lower limits described above. For example, it can be 0.50 to 0.95 times, 0.55 to 0.90 times, 0.60 to 0.85 times, 0.65 to 0.80 times, or 0.70 to 0.75 times. When height H2 is 0.50 times or greater relative to height H1, strength tends to be further improved. When height H2 is 0.95 times or less relative to height H1, shading tends to be further suppressed.

[0089] By reducing the height H2 of the second vertex 32b, shading tends to be further suppressed. Furthermore, by increasing the height H2 of the second vertex 32b, the strength of the metal mask 20 tends to be further improved. Furthermore, the range of the height H2 of the second vertex 32b can also be defined by a combination of any one of the plurality of candidate lower limit values ​​described above and any one of the plurality of candidate upper limit values ​​described above.

[0090] The radius of curvature of the second apex 32b is preferably 2.0 μm or greater, and may be 1.5 μm or greater, 3.0 μm or greater, 3.5 μm or greater, or 4.0 μm or greater. The radius of curvature of the second apex 32b is preferably 18.0 μm or less, and may be 17.0 μm or less, 16.0 μm or less, 15.0 μm or less, or 14.0 μm or less.

[0091] By reducing the radius of curvature of the second vertex 32b, shading tends to be further suppressed. Furthermore, by increasing the radius of curvature of the second vertex 32b, the strength of the metal mask 20 tends to be further improved. Furthermore, the range of the radius of curvature of the second vertex 32b can also be defined by a combination of any one of the plurality of candidate lower limit values ​​and any one of the plurality of candidate upper limit values.

[0092] Furthermore, the curvature of the second apex portion 32b is preferably not less than 0.03 μm-1, and may be not less than 0.05 μm-1, or not less than 0.07 μm-1, or not less than 0.10 μm-1, or not less than 0.15 μm-1. Furthermore, the curvature of the second apex portion 32b is preferably not more than 0.80 μm-1, or not more than 0.70 μm-1, or not more than 0.60 μm-1, or not more than 0.50 μm-1, or not more than 0.40 μm-1, or not more than 0.30 μm-1.

[0093] By reducing the curvature of the second vertex portion 32b, the strength of the metal mask 20 tends to be further improved. Furthermore, by increasing the curvature of the second vertex portion 32b, shading tends to be further suppressed. Furthermore, the range of the curvature of the second vertex portion 32b can also be defined by a combination of any one of the plurality of candidate lower limit values ​​described above and any one of the plurality of candidate upper limit values ​​described above.

[0094] The peripheral region 23 is located around the active region 22 and is arranged to surround the active region 22. The peripheral region 23 supports the active region 22 by being located around the active region 22, and is not a region having through-holes 25 for the passage of the vapor deposition material. However, for various purposes, the peripheral region 23 may also have through-holes other than those provided for the passage of the vapor deposition material, or may have recesses formed by half-etching or the like.

[0095] The surrounding area may include ends 17 of the metal mask fixed to the frame. As shown in FIG1 , in the case of a long, rod-shaped metal mask 20, the ends 17 may be located at both ends in the longitudinal direction. Alternatively, the ends 17 may have a U-shaped cutout or the like. Alternatively, in the case of a large metal mask having a shape substantially identical to the frame, the ends 17 may be located at the periphery of the metal mask. Furthermore, the ends 17 may be formed by partially cutting off the metal mask after it is fixed to the frame.

[0096] In one embodiment of the present invention, the end portion 17 may be integrally formed with the surrounding area 23 as shown in FIG4 , or may be formed of a separate component from the surrounding area. In this case, the end portion 17 may be joined to the rest of the surrounding area by, for example, welding.

[0097] An example of the through hole 25 in the effective area 22 will be described in more detail with reference mainly to Figures 6 to 9. Figure 6 is a partial top view of the effective area 22 of the metal mask 20 as viewed from the second surface 20b.

[0098] FIG7 is a cross-sectional view taken along line AA' of FIG6 , FIG8 is a cross-sectional view taken along line BB' of FIG6 , and FIG9 is a cross-sectional view taken along line CC' of FIG6 . Specifically, FIG7 is a cross-sectional view of the effective area 22 of the metal mask 20 cut along a direction alternately passing through the through-holes 25 and the first apex 32a, in other words, in the same direction as the minor axis 27. FIG8 is a cross-sectional view of the effective area 22 of the metal mask 20 cut along a direction alternately passing through the through-holes 25 and the second apex 32b, in other words, in the same direction as the major axis 26. FIG9 is a cross-sectional view of the effective area 22 of the metal mask 20 cut along a ridgeline 33 between the through-holes 25.

[0099] As shown in FIG6 , at least a portion of the plurality of through-holes 25 are arranged at specific intervals along intersecting first and second directions D1 and D2. In the example shown in FIG6 , the first and second directions D1 and D2 may be orthogonal to each other. The first and second directions D1 and D2 may coincide with the length or width of the metal mask 20, or may be inclined relative to the length or width of the metal mask 20. For example, the first direction D1 may be inclined at 45 degrees relative to the length of the metal mask 20.

[0100] The distance between through-holes 25 in active area 22 is not particularly limited. For example, when metal mask 20 (metal mask device 10) is used to manufacture displays (approximately 2 inches to 5 inches) for mobile phones or digital cameras, the distance between through-holes 25 can be set to approximately 28 μm to 254 μm.

[0101] Furthermore, the orientation of the through-holes 25 arranged along the first direction D1 or the second direction D2 is not particularly limited. For example, as shown in FIG6 , the through-holes 25 may be arranged so that the first direction D1 or the second direction D2 is parallel to the direction of the major axis 26 of the through-holes 25. Alternatively, the through-holes 25 may be arranged so that the first direction D1 or the second direction D2 is parallel to the direction of the minor axis 27 of the through-holes 25.

[0102] The through-hole 25 is not particularly limited as long as its opening shape has a minor axis 27 and a major axis 26. The opening shape may be a substantially rectangular or elliptical shape, or a polygonal shape such as a hexagon or octagon extending in one direction. The ratio of the minor axis 27 to the major axis 26 (minor axis / major axis) is preferably 0.30 or greater, and may also be 0.40 or greater, 0.50 or greater, 0.60 or greater, 0.70 or greater, 0.80 or greater, or 0.90 or greater. Furthermore, the ratio of the minor axis 27 to the major axis 26 (minor axis / major axis) is preferably 0.90 or less, and may also be 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, or 0.40 or less.

[0103] Furthermore, the range of the ratio (minor axis / major axis) can also be defined by a combination of any one of the plurality of candidate lower limit values ​​and any one of the plurality of candidate upper limit values. Furthermore, the minor axis 27 and the major axis 26 may be orthogonal. For example, when the through-hole 25 is substantially rectangular or substantially elliptical, the minor axis 27 and the major axis 26 may be orthogonal.

[0104] As shown in Figures 6 to 9, a plurality of through-holes 25 penetrate the metal mask 20 in the thickness direction. The through-holes 25 can also be formed by connecting a first recess 30 formed by etching on the first surface 51a of the metal plate 51 with a second recess 35 formed by etching on the second surface 51b of the metal plate 51. Furthermore, the first surface 51a of the metal plate 51 corresponds to the first surface 20a of the metal mask 20.

[0105] The etching of the metal plate 51 is performed isotropically from the holes in the resist pattern toward various directions. Therefore, the cross-sectional area of ​​the first recess 30 or the second recess 35 at each position along the thickness direction of the metal mask 20 gradually decreases as the cross-sectional area increases from the surface toward the thickness direction.

[0106] In the through-hole 25 formed by the connection between the first recess 30 and the second recess 35, the first wall surface 31 of the first recess 30 and the second wall surface 36 of the second recess 35 are connected via a circumferential connecting portion 41. At the connecting portion 41, the direction in which the wall surface of the through-hole 25 expands changes. For example, the direction in which the wall surface expands changes discontinuously at the connecting portion 41. In one embodiment of the present invention, the opening area of ​​the through-hole 25 is minimized when viewed from above at the connecting portion 41. Furthermore, although not shown, the opening area of ​​the through-hole 25 may also be minimized at a location in the thickness direction of the metal mask 20 other than the connecting portion 41.

[0107] On the second surface 20b side of the active area 22, the second recesses 35 of two adjacent through-holes 25 can also be connected by the ridge line 33. In other words, the second surface 51b of the metal plate 51 constituting the metal mask 20 does not need to remain between the two adjacent second recesses 35. Such through-holes 25 can also be formed by etching the metal plate 51 so that the second surface 51b of the metal plate 51 does not remain between the two adjacent second recesses 35, as in the manufacturing method described below. Furthermore, the second surface 51b of the metal plate 51 corresponds to the second surface 20b of the metal mask 20.

[0108] During the evaporation step using the metal mask 20, the evaporation material 98 adheres to the substrate 92 through the second recess 35, whose opening area gradually decreases. A portion of the evaporation material 98 moves from the crucible 94 toward the substrate 92 along the thickness direction N of the substrate 92. However, another portion of the evaporation material 98 may move in a direction oblique to the thickness direction N of the substrate 92, as shown in FIG7 , which is a direction F1 from the second surface 20 b toward the first surface 20 a, or in FIG8 , which is a direction F2 from the second surface 20 b toward the first surface 20 a.

[0109] As a result, a portion of the vapor deposition material 98 moving in the inclined directions F1 and F2 reaches and adheres to the second wall surface 36 of the second recess 35 before passing through the through-hole 25 and reaching the substrate 92, thereby creating a shadow. As the proportion of vapor deposition material 98 adhering to the second wall surface 36 of the second recess 35 increases, the utilization efficiency of the vapor deposition material 98 during the vapor deposition step decreases.

[0110] In this regard, a more specific study is conducted on the case where the through-hole has an anisotropic shape, such as a minor axis 27 and a major axis 26. As shown in FIG6 , when the through-hole has an anisotropic shape, such as a minor axis 27 and a major axis 26, a relatively large first region R1 and a relatively small second region R2 may exist.

[0111] The through-hole 25 may also include a first recess 30 located on the first surface 20a side, a second recess 35 located on the second surface 20b side, a connecting portion 41, a first angle θ1, and a second angle θ2. The connecting portion 41 is a ridge connecting the first recess 30 and the second recess 35. At the connecting portion 41, the direction in which the wall surface of the through-hole 25 expands changes discontinuously. In one embodiment of the present invention, the through-hole 25 may have its smallest opening area in a plan view at the connecting portion 41. Alternatively, the through-hole 25 may have its smallest opening area at a location in the thickness direction of the metal mask 20 other than the connecting portion 41.

[0112] The first angle θ1 is the angle formed by the straight line K1 with respect to the thickness direction N of the metal mask. Here, the straight line K1 passes through the portion P1a of the connecting portion 41 closest to the first vertex 32a and the portion P2a of the first vertex 32a closest to the connecting portion 41.

[0113] The second angle θ2 is the angle formed by the straight line K2 with respect to the thickness direction N of the metal mask. Here, the straight line K2 passes through the portion P1b of the connecting portion 41 closest to the second vertex 32b and the portion P2b of the second vertex 32b closest to the connecting portion 41.

[0114] Here, it is assumed that unetched ribs remain in both the first region R1 and the second region R2. In this case, as shown in FIG7 , when viewed along a plane that cuts through the active region 22 of the metal mask 20 in the same direction as the minor axis 27, the angle θ1 of the direction F1 connecting the first vertex 32a and the connecting portion 41 is relatively gentle. However, as shown by the dashed line in FIG8 , when viewed along a plane that cuts through the active region 22 of the metal mask 20 in the same direction as the major axis 26, the angle θ3 of the direction F3 connecting the vertex 32c and the connecting portion 41 is relatively steep.

[0115] For example, if the through-hole 25 has an anisotropic shape with a minor axis 27 and a major axis 26, assuming ribs are present in both the first region R1 and the second region R2, even if the height H1 of the first vertex located in the minor axis direction D2 of the through-hole 25 is high, the distance from the through-hole to the first vertex is relatively long, making shading less likely. On the other hand, the distance from the second vertex located in the major axis direction D1 of the through-hole 25 is relatively short. Therefore, if the height H2 of the second vertex is high, shading is more likely to occur.

[0116] In contrast, in one embodiment of the present invention, as shown in FIG8 , the height H2 of the second vertex 32b, which appears when the effective area 22 of the metal mask 20 is cut along the same direction as the long axis 26, is set lower than the height H1 of the first vertex 32a. By lowering the height H2 of the second vertex 32b, which is prone to shading, shading is less likely to occur. Meanwhile, by raising the height H2 of the first vertex 32a, which is less likely to shading, the strength of the metal mask can be improved. More specifically, as shown in FIG8 , the second vertex can be configured such that the second wall surfaces 36 of two adjacent second recesses 35 in the direction of the long axis 26 meet on the second surface 20b side. This allows the angle θ2 between the direction F2 connecting the connecting portion 41 and the second vertex and the thickness direction of the metal mask to be more gradual.

[0117] By having a second vertex portion formed by etching in the second region R2 surrounded by the short axis 27, the angle θ2 of the direction F2 can be made closer to the angle θ1 of the direction F1, and the way in which shading is generated can be less likely to differ depending on the directions of the short axis 27 and the long axis 26.

[0118] Furthermore, the angle θ1 formed by the portion of the connecting portion 41 closest to the first vertex portion 32a and the straight line of the first vertex portion 32a relative to the thickness direction N of the metal mask 20 and the angle θ2 formed by the portion of the connecting portion 41 closest to the second vertex portion 32b and the straight line of the second vertex portion 32b relative to the thickness direction N preferably have a relationship of θ2≧θ1.

[0119] The angle θ1 is preferably 25° or more, and may be 30° or more, 35° or more, or 40° or more. Furthermore, the angle θ1 is preferably 75° or less, and may be 70° or less, 65° or less, or 60° or less.

[0120] The angle θ2 is preferably 40° or more, and may be 45° or more, 50° or more, or 55° or more. Furthermore, the angle θ2 is preferably 85° or less, and may be 80° or less, 75° or less, 70° or less, or 65° or less.

[0121] By setting angle θ1 and angle θ2 as described above, there is a tendency to reduce differences in the way shading occurs depending on the directions of minor axis 27 and major axis 26. Furthermore, the numerical ranges for angle θ1 and angle θ2 can also be defined by combining any one of the plurality of candidate lower limit values ​​described above with any one of the plurality of candidate upper limit values ​​described above.

[0122] Furthermore, the first recess 30 and the second recess 35 can also be distinguished based on their depth. For example, as shown in FIG7 , the through-hole 25 may have a first recess 30 of height H3 and a second recess 35 of height H4. Here, height H3 is the height from the first surface 20a to the connecting portion 41. Furthermore, height H4 is the height from the second surface 20b to the connecting portion 41. In this case, height H3 is preferably lower than height H4. Alternatively, the surface having the first recess 30 at this depth relationship may be referred to as the first surface 20a, and the surface having the second recess 35 may be referred to as the second surface 20b.

[0123] By increasing the ratio (H4 / H3) as described above, the utilization efficiency of the vapor deposition material and the vapor deposition accuracy tend to be further improved. Furthermore, by decreasing the ratio (H4 / H3), deformation or cracking of the effective area 22 tends to be suppressed. Furthermore, the range of the ratio (H4 / H3) can also be defined by a combination of any one of the multiple candidate lower limit values ​​described above and any one of the multiple candidate upper limit values ​​described above.

[0124] The depth relationship between the first recess 30 and the second recess 35 can also be replaced by the size of the openings of the first recess 30 and the second recess 35. For example, the opening size of the first recess 30 can also be smaller than the opening size of the second recess 35.

[0125] A method for manufacturing a metal mask according to one embodiment of the present invention includes the following steps: preparing a metal plate 51 having a first surface 51a and a second surface 51b located on the opposite side of the first surface 51a; and an etching step, which forms a metal mask 20 by etching the metal plate 51.

[0126] The method for manufacturing the metal mask 20 according to one embodiment of the present invention will be described primarily with reference to Figures 10 to 15. Figure 10 shows a diagram of a manufacturing apparatus 70 for manufacturing the metal mask 20 using a metal plate 51. First, a roll 50 comprising the metal plate 51 wound around a shaft 52 is prepared. The metal plate 51 of the roll 50 is then unwound from the shaft 52 and transported sequentially to a resist film forming apparatus 71, an exposure and development apparatus 72, an etching apparatus 73, a film stripping apparatus 74, and a separation apparatus 75 shown in Figure 10. During this process, through-holes 25 are formed in the metal plate 51. Furthermore, by cutting the long metal plate, a metal mask 20 formed from a single sheet of metal plate can be obtained.

[0127] Furthermore, FIG10 shows an example in which the metal plate 51 is transported in its longitudinal direction to move between devices, but the present invention is not limited to this. For example, after the metal plate 51 is provided with a resist film in the resist film forming device 71, it may be rewound onto the shaft member 52 and the rolled metal plate 51 may be supplied to the exposure and development device 72. Alternatively, after the metal plate 51 is provided with a resist film and subjected to exposure and development in the exposure and development device 72, it may be rewound onto the shaft member 52 and the rolled metal plate 51 may be supplied to the etching device 73. Alternatively, after the metal plate 51 is etched in the etching device 73, it may be rewound onto the shaft member 52 and the rolled metal plate 51 may be supplied to the film stripping device 74. Alternatively, after the resin 54, etc., described below, is removed from the film stripping device 74, it may be rewound onto the shaft member 52 and the rolled metal plate 51 may be supplied to the separation device 75.

[0128] The resist film forming device 71 forms a resist film on the surface of the metal plate 51. The exposure and development device 72 performs exposure and development on the resist film, patterning the resist film to form a resist pattern. The etching device 73 etches the metal plate 51 using the resist pattern as a mask, thereby forming through-holes 25 in the metal plate 51. The film stripping device 74 removes the resist pattern or components such as the resin 54 described below, which are provided to protect the unetched portion of the metal plate 51 from the etching solution. The separation device 75 performs a separation step, separating the portion of the metal plate 51 where the plurality of through-holes 25 corresponding to one sheet of the metal mask 20 are formed. In this manner, the metal mask 20 can be obtained.

[0129] In one embodiment of the present invention, multiple through-holes 25 are formed in a manner that allows multiple metal masks 20 to be fabricated from a metal plate 51. In other words, multiple metal masks 20 are allocated to the metal plate 51. For example, multiple through-holes 25 are formed in the metal plate 51 so that multiple active areas 22 are arranged in the width direction of the metal plate 51 and multiple active areas 22 for the metal masks 20 are arranged in the length direction of the metal plate 51.

[0130] Hereinafter, each step of the method for manufacturing the metal mask 20 will be described in detail.

[0131] First, a wound body 50 including a metal plate 51 wound around a shaft member 52 is prepared. As a method for producing the metal plate 51 having a desired thickness, a rolling method, a plating film forming method, etc. can be used.

[0132] Next, using the resist film forming apparatus 71, resist films 53a and 53b are formed on the first surface 51a and second surface 51b of the metal plate 51 unwound from the unwinding apparatus, as shown in FIG11 . The resist films 53a and 53b can also be formed by, for example, attaching a dry film containing a photosensitive resist material, such as an acrylic photocurable resin, to the first surface 51a and second surface 51b of the metal plate 51. Alternatively, the resist films 53a and 53b can also be formed by, for example, applying a coating liquid containing a photosensitive resist material to the first surface 51a and second surface 51b of the metal plate 51 and then drying the coating liquid.

[0133] The resist films 53a and 53b may be either negative or positive type, but preferably negative type.

[0134] The thickness of the resist films 53a and 53b may be, for example, 15 μm or less, 10 μm or less, 6 μm or less, or 4 μm or less. Furthermore, the thickness of the resist films 53a and 53b may be, for example, 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more. The range of the thickness of the resist films 53a and 53b may also be defined by a combination of any one of the plurality of candidate upper limit values ​​described above and any one of the plurality of candidate lower limit values ​​described above.

[0135] Next, the resist films 53a and 53b are exposed and developed using the exposure and development device 72. This allows a first resist pattern 53c to be formed on the first surface 51a of the metal plate 51, and a second resist pattern 53d to be formed on the second surface 51b of the metal plate 51, as shown in FIG12 . For example, when using a negative-type resist film, a glass substrate that prevents light from passing through the area of ​​the resist film to be removed can be placed on the resist film, and the resist film can be exposed through the glass substrate, and then developed.

[0136] Then, an etching step is performed using the etching device 73. In this etching step, the metal plate 51 is etched using the first resist pattern 53c and the second resist pattern 53d as a mask, thereby forming the metal mask 20. The etching step may also include a first surface etching step and a second surface etching step.

[0137] First, as shown in Figure 13, a first-side etching step is performed. In this first-side etching step, the areas of the first surface 51a of the metal plate 51 not covered by the first resist pattern 53c are etched using a first etching liquid. For example, the first etching liquid is sprayed from a nozzle located opposite the first surface 51a of the conveyed metal plate 51 through the first resist pattern 53c toward the first surface 51a of the metal plate 51. At this time, the second surface 51b of the metal plate 51 may also be covered with a film or the like resistant to the first etching liquid.

[0138] As a result of the first-side etching step, as shown in FIG13 , the first etching solution is used to etch the areas of the metal plate 51 not covered by the first resist pattern 53 c. This forms a plurality of first recesses 30 on the first side 51 a of the metal plate 51. For example, the first etching solution may contain ferric chloride solution and hydrochloric acid.

[0139] Next, as shown in FIG14 , a second-side etching step is performed. In this second-side etching step, a second etching solution is used to etch the area of ​​the second side 51b of the metal plate 51 not covered by the second resist pattern 53d. This forms the second recess 35 on the second side 51b of the metal plate 51. Etching of the second side 51b is continued until the first recess 30 and the second recess 35 communicate with each other, thereby forming the through-hole 25. As with the first etching solution described above, the second etching solution can contain, for example, ferric chloride solution and hydrochloric acid. Furthermore, when etching the second side 51b, the first recess 30 can be covered with a resin 54 resistant to the second etching solution, as shown in FIG14 .

[0140] In the second-side etching step, as shown in FIG14 , etching is performed so that the first vertex portion remains unetched in the first region R1, or so that the height H1 of the first vertex portion is relatively high. Specifically, etching can be performed in the first region R1 so that two adjacent second recesses 35 are not connected, or so that two adjacent second recesses 35 are connected. In this case, for example, by adjusting the etching to avoid excessive etching, the height H1 and θ1 of the first vertex portion 32a can be adjusted.

[0141] On the other hand, as shown in Figure 15 , etching is performed in the second region R2 so that the height H2 of the second apex becomes relatively low. Specifically, etching can be performed in the second region R2 so that two adjacent second recesses 35 are connected. The height H2 and θ2 of the second apex 32b can be adjusted according to the progress of etching. At the point where two adjacent second recesses 35 are connected, the two adjacent second recesses 35 meet, and the ridgeline 33 is separated from the first resist pattern 53c. Etching at this ridgeline 33 also progresses in the thickness direction of the metal plate 51. As a result, the second resist pattern 53d is peeled off from the metal plate 51.

[0142] By doing so, the height H1 of the first vertex 32a can be made greater than the height H2 of the second vertex 32b. Furthermore, the top area of ​​the first vertex 32a (when it is a rib) or the curvature and radius of curvature of the second vertex 32b can also be adjusted by etching. This etching adjustment can also be performed by adjusting etching conditions or the size or shape of the holes in the second resist pattern 53d.

[0143] Next, a method for manufacturing an organic EL display device using the metal mask 20 of this embodiment will be described with reference to FIG2 . The organic EL display device may also include a substrate 92 and a patterned vapor-deposition layer containing a vapor-deposition material 98 in a laminated state. The method for manufacturing the organic EL display device includes a vapor deposition step of vapor-depositing the vapor-deposition material 98 onto a substrate such as the substrate 92 using the metal mask 20.

[0144] During the evaporation step, the metal mask apparatus 10 is first positioned so that the metal mask 20 faces the substrate 92. Alternatively, a magnet (not shown) can be used to secure the metal mask 20 to the substrate 92. Alternatively, the interior of the evaporation apparatus 90 can be maintained in a vacuum environment. In this state, the evaporation material 98 evaporates and flies through the metal mask 20 toward the substrate 92, thereby depositing the evaporation material 98 onto the substrate 92 in a pattern corresponding to the through-holes 25 of the metal mask 20.

[0145] Furthermore, the method for manufacturing an organic EL display device may include various steps in addition to the evaporation step of evaporating the evaporation material 98 onto a substrate such as the substrate 92 using the metal mask 20. For example, the method for manufacturing an organic EL display device may include the step of forming a first electrode on the substrate. The evaporation layer is formed on the first electrode. The method for manufacturing an organic EL display device may also include the step of forming a second electrode on the evaporation layer. The method for manufacturing an organic EL display device may also include the step of sealing the first electrode, the evaporation layer, and the second electrode provided on the substrate 92.

[0146] The vapor-deposited layers formed on a substrate such as substrate 92 using metal mask 20 are not limited to the aforementioned light-emitting layer and may also include other layers. For example, the vapor-deposited layers may include, in order from the first electrode side, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. In this case, the vapor deposition steps using metal mask 20 corresponding to each layer may be performed separately.

[0147] Furthermore, various modifications can be made to the above-described embodiment. Below, modifications are described with reference to the accompanying drawings as needed. In the following description and the drawings used therein, components that can be configured similarly to the above-described embodiment are denoted by the same reference numerals as the corresponding components in the above-described embodiment, and duplicate descriptions are omitted. Furthermore, where it is clear that the effects achieved in the above-described embodiment can also be achieved in the modifications, their descriptions may be omitted.

[0148] (Variation Example) As a first variation, in the above description, a rib is used as the main example of the first vertex portion 32a, but the first vertex portion 32a does not necessarily have to be a rib, and can also be a portion that becomes the maximum value in the ridge line 33 formed by the combination of adjacent second recesses 35, like the second vertex portion 32b.

[0149] As a second variation, the step of forming the second recess 35 may be performed before the step of forming the first recess 30 , or the step of forming the first recess 30 and the step of forming the second recess 35 may be performed in parallel.

[0150] As a second variation, a through hole may be formed from the inside of the first recess 30 or the second recess 35 to the other surface of the metal plate 51 by irradiating the first recess 30 or the second recess 35 with laser light using a laser irradiator. [Example]

[0151] The present invention is described in more detail below using examples and comparative examples. The present invention is not limited to the following examples.

[0152] (Example) Using the above-described metal mask manufacturing method, a first recess and a second recess were formed in a metal plate to produce a metal mask having through-holes including the first and second recesses. The through-holes were formed in the pattern shown in FIG6 , with a generally rectangular shape having a minor axis of 40 μm and a major axis of 50 μm.

[0153] Furthermore, a first vertex portion remaining unetched is formed in the first region R1 surrounded by the major axes 26 of the four through-holes, and a second vertex portion is formed by etching in the second region R2 surrounded by the minor axes 27 of the four through-holes. The metal plate forming the base material of the metal mask is made of Invar alloy.

[0154] (Comparative Example) A metal mask is obtained in the same manner as in the embodiment except that apex portions are formed in both the first region R1 and the second region R2 and remain without being etched.

[0155] (Strength Evaluation) The metal shields produced in the Examples and Comparative Examples were used to evaluate their strength. Specifically, the metal shields were visually inspected for defects such as wavy shapes when installed on the frame. Based on these observations, the strength was evaluated according to the following criteria. (Evaluation Criteria) A: No wavy or other adverse conditions occurred D: Produces wavy shapes and other undesirable conditions

[0156] (Evaluation of Shade) Using the metal masks prepared in the Examples and Comparative Examples as described above, a vapor deposition step was performed to deposit the vapor deposition material onto the glass substrate to form a vapor deposition layer. The ratio of the minor axis to the major axis length of the vapor deposition layer relative to the ratio of the minor axis to the major axis length of the through-hole was then calculated. Based on this value, shading was evaluated according to the following evaluation criteria. Evaluation value = (ratio of the length of the short axis to the long axis of the vapor deposition layer) / (ratio of the length of the short axis to the long axis of the through hole) (Evaluation Criteria) A: The evaluation value is 0.95 or above and 1.05 or below B: The evaluation value is 0.90 or higher and less than 0.95, or exceeds 1.05 and is less than 1.10. C: The evaluation value is 0.85 or higher and less than 0.90 or more than 1.10 and less than 1.15 D: The evaluation value is less than 0.85 or exceeds 1.15

[0157] [Table 1] T [μm] H1 [μm] H2 [μm] H2 / H1 θ1[°] θ2[°] Area of ​​the first vertex [μm 2] Radius of curvature of the second vertex R [μm] Curvature of the second vertex [μm -1] strength shade Example 1 25 25 17 0.68 39.1 51.4 11 3.6 0.28 A A Example 2 25 25 twenty two 0.88 37.8 42.4 twenty four 2.0 0.51 A A Example 3 25 20 18 0.90 49.3 49.4 0 3.1 0.32 A A Example 4 20 20 12 0.60 54.5 68.5 49 6.5 0.15 A A Example 5 30 30 20 0.67 53.1 63.9 49 6.6 0.15 A A Example 6 35 35 28 0.80 64.3 68.2 64 12 0.08 A A Example 7 50 50 30 0.60 54.5 68.2 64 18 0.06 A A Example 8 25 25 18 0.72 25.6 43.2 121 8.7 0.11 A A Comparative Example 1 25 25 25 1.00 36.1 31.9 25 - - A C Comparative Example 2 20 10 10 1.00 72.6 70.5 0 4.5 0.22 D A Comparative Example 3 25 25 25 1.00 33.9 30.5 64 - - A D

[0158] As described above, the metal mask of the embodiment in which the height H1 of the first vertex is higher than the height H2 of the second vertex has excellent strength and can suppress shading. On the other hand, the metal masks of Comparative Examples 1 and 3, in which the height H1 of the first vertex and the height H2 of the second vertex are the same and have the same thickness T, maintain strength but are prone to shading. Furthermore, the metal mask of Comparative Example 2, in which the height H1 of the first vertex and the height H2 of the second vertex are the same and are thinner, can suppress shading but has low strength and causes handling problems.

[0159] Furthermore, when the height H2 is 0.50 times or more relative to the height H1, a tendency toward further improvement in strength is observed, and when the height H2 is 0.95 times or less relative to the height H1, a tendency toward further suppression of shading is observed. [Industrial Applicability]

[0160] The metal mask of the present invention has industrial applicability as a metal mask for manufacturing an organic EL display device.

[0161] 10: Metal mask device 15: Framework 17:End 20:Metal Mask 20a:Side 1 20b: Side 2 22: Valid area 23: Surrounding area 25:Through hole 25a: 1st through hole 25b: Second through hole 25c: 3rd through hole 25d: 4th through hole 25e: 5th through hole 25f: 6th through hole 26: Long axis 26a: 1st major axis 26b: 2nd major axis 26c: 3rd long axis 26d: 4th major axis 26e: 5th major axis 26f: 6th major axis 27: short axis 27a: 1st short axis 27b: Second short axis 27c: 3rd short axis 27d: 4th minor axis 27e: 5th minor axis 27f: 6th minor axis 30: 1st concave part 31: 1st wall 32a: 1st vertex 32b: Second vertex 32c: Vertex 33: Ridge 35: 2nd concave part 36: 2nd wall 41: Connecting part 50: winding body 51:Metal plate 51a: Page 1 51b: Page 2 52: shaft component 53a: Anti-corrosion film 53b: Anti-corrosion film 53c: First resist pattern 53d: Second resist pattern 54: Resin 70: Manufacturing device 71: Resist film forming device 72: Exposure and development device 73: Etching device 74: Film stripping device 75: Separation device 90: Evaporation device 92:Substrate 94: Crucible 96: Heater 98: Evaporation material 99A: 1st vapor deposition layer 99B: Second vapor deposition layer 99C: 3rd vapor deposition layer 100: Organic EL display device D1: Direction 1 D2: Direction 2 D3: Direction F1: Direction F2: Direction F3: Direction H1: Height H2: Height H3: Height H4: Height K1: Straight line K2: Straight line M1: Size M2: Size M3: Size M4: Size N: direction P1a: Part P1b: Part P2a: Part P2b: Part R1: Area 1 R2: Area 2 T:Height θ1: 1st angle θ2: Second angle θ3: acute angle θ4: Angle

Claims

1. A metal shield having a first surface and a second surface located opposite to the first surface, the first surface having a through hole, a first vertex portion, and a second vertex portion, the through hole having a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole, the first through hole having a first minor axis and a first major axis, the second through hole having a second minor axis and a second major axis, the third through hole having a third minor axis and a third major axis, the fourth through hole having a fourth minor axis and a fourth major axis, the fifth through hole having a fifth minor axis and a fifth major axis, the sixth through hole having a sixth minor axis and a sixth major axis, the first major axis being parallel to the second major axis and located beside the second major axis in a direction D2 intersecting the first major axis. The first minor axis is parallel to the fifth minor axis and is located next to the fifth minor axis in a direction D1 parallel to the first major axis. The third major axis is parallel to the fourth major axis and is located next to the fourth major axis in a direction D1 parallel to the first major axis. The third minor axis is parallel to the sixth minor axis and is located next to the sixth minor axis in a direction D2 intersecting the first major axis. The first vertex is located between the first major axis and the second major axis and between the third major axis and the fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and the height H1 of the first vertex is higher than the height H2 of the second vertex.

2. The metal shield as claimed in claim 1, wherein the first vertex portion and the second vertex portion exist alternately in the direction D3 passing through the first vertex portion and the second vertex portion.

3. The metal shield as claimed in claim 2, wherein the acute angle formed by the aforementioned direction D1 and the aforementioned direction D3 is more than 30° and less than 60°.

4. The metal shield as claimed in claim 1, wherein the height H1 is more than 0.60 times and less than 1.00 times the height T from the first surface to the second surface.

5. The metal shield as claimed in claim 1, wherein the height H2 is more than 0.30 times and less than 0.95 times the height T from the first surface to the second surface.

6. The metal shield as claimed in claim 1, wherein the height H2 of the second vertex portion is less than 0.90 times the height H1 of the first vertex portion.

7. The metal shield of claim 1, wherein the through hole has a first recess on the first surface side, a second recess on the second surface side, a connecting portion, a first angle θ1, and a second angle θ2, the connecting portion being an edge connecting the first recess and the second recess, the first angle θ1 being the angle formed by the straight line (K1) of the connecting portion closest to the first vertex (P1a) and the first vertex portion closest to the connecting portion (P2a) with respect to the thickness direction N of the metal shield, the second angle θ2 being the angle formed by the straight line (K2) of the connecting portion closest to the second vertex (P1b) and the second vertex portion closest to the connecting portion (P2b) with respect to the thickness direction N of the metal shield, and the first angle θ1 and the second angle θ2 have a relationship of θ2 ≥ θ1.

8. The metal mask as claimed in claim 1, wherein the radius of curvature of the front end of the second vertex portion is more than 2.0 μm and less than 18 μm.

9. The metal shield of claim 1, wherein the opening shape of the through hole is generally rectangular or generally elliptical.

10. A method for manufacturing a metal mask, comprising the following steps: preparing a metal plate having a first surface and a second surface located opposite to the first surface; and an etching step, wherein the metal mask is formed by etching the metal plate; the metal mask having a first surface and a second surface located opposite to the first surface, the first surface having a through hole, a first vertex portion, and a second vertex portion, the through hole having a first through hole, a second through hole, a third through hole, a fourth through hole, a fifth through hole, and a sixth through hole, the first through hole having a first minor axis and a first major axis, the second through hole having a second minor axis and a second major axis, the third through hole having a third minor axis and a third major axis, the fourth through hole having a fourth minor axis and a fourth major axis, and the fifth through hole having a fifth minor axis and a fifth major axis. The aforementioned sixth through hole has a sixth minor axis and a sixth major axis. The aforementioned first major axis is parallel to the aforementioned second major axis and is located next to the aforementioned second major axis in a direction D2 intersecting the aforementioned first major axis. The aforementioned first minor axis is parallel to the aforementioned fifth minor axis and is located next to the aforementioned fifth minor axis in a direction D1 parallel to the aforementioned first major axis. The aforementioned third major axis is parallel to the aforementioned fourth major axis and is located next to the aforementioned fourth major axis in a direction D1 parallel to the aforementioned first major axis. The aforementioned third minor axis is parallel to the aforementioned sixth minor axis and is located next to the aforementioned sixth minor axis in a direction D2 intersecting the aforementioned first major axis. The aforementioned first vertex portion is located between the aforementioned first major axis and the aforementioned second major axis, and between the aforementioned third major axis and the aforementioned fourth major axis. The second vertex is located between the first minor axis and the fifth minor axis and between the third minor axis and the sixth minor axis, and the height H1 of the first vertex is higher than the height H2 of the second vertex.

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