Large-size mask sheet for OLED evaporation and mask assembly comprising same

Abstract

The invention relates to a large-size mask sheet for OLED (Organic Light Emitting Diode) evaporation and a mask assembly comprising the large-size mask sheet. Specifically, according to the present invention, a plurality of mask sheets manufactured using an original sheet or individual mask rods are bonded to increase the size, thereby providing a mask sheet for OLED vapor deposition suitable for manufacturing large-size displays of 1, 500 mm * 1, 850 mm (sixth generation) or more, which are difficult to manufacture using an invar sheet material original sheet, and a mask assembly comprising the same. Further, when the size is enlarged by the joining between the sheets, a weld site may be minimized while effectively absorbing stresses caused by welding and / or tension. Therefore, when a large-sized sheet is manufactured, wrinkles occurring in the sheet can be minimized, the sheet can sufficiently cling to a substrate, and scratches occurring when the sheet is in contact with the substrate can be minimized. In addition, excellent unit positioning accuracy can be ensured and product defects can be minimized.

Description

Technical Field

[0001] The present invention relates to a large-sized mask sheet for OLED evaporation and a mask assembly including the same. Specifically, the present invention relates to a large-sized mask sheet for OLED evaporation formed by bonding a sheet and a lip edge portion between the sheets and a mask assembly including the same. Background Art

[0002] Well-known flat panel display devices include liquid crystal display devices (LCD) and organic light emitting display devices (OLED). Among them, OLED is a thin film light emitting diode whose light emitting layer is made of organic compounds. In the usual OLED manufacturing process, when thin film layers such as electrode layers, organic light emitting layers and insulating films are stacked and patterned, an evaporation process is performed by using a mask assembly with a corresponding pattern.

[0003] In the evaporation process, an open metal mask (OMM) is used to form a functional organic common layer on the OLED substrate, and a fine metal mask (FMM) is used in the RGB evaporation process for separately evaporating pixels that emit red (R), green (G) and blue (B) light.

[0004] The mask assembly used in the evaporation process has a structure in which a mask sheet or a mask bar, which is a relatively thin metal film, is bonded to a mask frame having a relatively solid structure. The mask frame is a frame structure in the form of a window frame or a door frame having a thickness of about 5 mm to 80 mm, and plays a role in stably maintaining the shape of the mask assembly. On the other hand, the mask sheet or the mask bar is formed by forming a predetermined pattern used in evaporation on a thin film metal sheet or strip having a thickness of about 0.01 mm to 5.00 mm.

[0005] Typically, for example, the mask assembly is made of a metal with a very small thermal expansion coefficient according to temperature changes, such as Invar alloy (Invar-36 Alloy). In addition, if the accuracy of the pattern is not required to be high, a stainless steel with high heat resistance, such as 420 stainless steel (SUS420), can be used to manufacture the mask frame to reduce costs. For example, an open metal mask (OMM) assembly used in the organic common layer evaporation process of an OLED display is manufactured by coating a dry photosensitive film (DFR) on both sides of the mask sheet, performing UV exposure, and then forming a pattern on the mask sheet by performing processes such as development and wet etching, and then joining the mask frame by a laser welding method in a stretched state.

[0006] On the other hand, the demand for large-size OLED panels is increasing greatly to meet the demand for various designs and the trend of large-size displays. On the other hand, the maximum size of the invar mask sheet original sheet currently supplied is only about 1100mm wide, so it is difficult to manufacture large-size OLED mask components using the original mask sheet.

[0007] In this regard, the applicant's previously authorized patent discloses a separate mask assembly form in which individual mask bars are crossed and stretched to be joined to a mask frame. In addition to the above-mentioned technology, attempts have been made to manufacture a large-sized mask sheet by joining a plurality of sheets in the form of original sheets, but when welding or joining the mask sheets, it is difficult to ensure the durability of the joint, and there are difficulties in the process due to wrinkles in the sheet, and welding protrusions are formed at the welding portion, which makes it difficult to adhere to the substrate or causes scratches on the substrate.

[0008] Prior art literature

[0009] Patent Literature

[0010] Korean Patent Publication No. 10-2022-0034993 (Publication Date: March 21, 2022) Summary of the invention

[0011] Technical issues

[0012] The present invention aims to provide a mask sheet for OLED evaporation and a mask assembly including the same, which is enlarged in size by joining multiple mask sheets manufactured using original sheets or individual mask rods, so that it can be used to manufacture large-size displays of 1,500mm×1,850mm (sixth generation) or more that were previously difficult to manufacture using Invar original sheets.

[0013] Specifically, the present invention aims to provide a mask sheet for OLED evaporation and a mask assembly including the same, which can minimize the welding parts when the size is enlarged through the joints between the sheets, and effectively absorb the stress caused by welding and / or tension, minimize the wrinkles of the sheet, achieve sufficient close contact with the substrate, and minimize the occurrence of scratches when in contact with the substrate, thereby ensuring excellent unit positioning accuracy and minimizing product defects.

[0014] The technical problems to be solved by the present invention are not limited to the technical problems described above. Through the following description, those skilled in the art can clearly understand other technical problems not mentioned.

[0015] Solutions to the problem

[0016] In this specification, a large-size mask sheet for OLED evaporation is provided, which is a large-size mask sheet formed by joining multiple sheet parts including one or more first unit opening parts, and the above-mentioned multiple sheet parts are joined to each other by joining between lip edges protruding from the joining area.

[0017] In one example, the mask sheets may be joined to each other by joining the lips and then stretched.

[0018] In one example, a space between the lips of the mask sheet formed by the engagement between the lips may be opened.

[0019] In one example, the space between the lips may be a second unit opening portion.

[0020] In one example, the space between the lips may be a first pseudo hole for absorbing tensile strain.

[0021] In one example, the joining between the lips may be performed by welding or bonding between metals.

[0022] In one example, the large-sized mask sheet for OLED evaporation may include one or more second dummy holes arranged at predetermined intervals from the bonding area of ​​the lip edges bonded to each other.

[0023] In one example, the lips may have a first thickness, the joined regions of the lips joined to each other overlap each other, and then the lips 150 may be embossed to have a second thickness less than or equal to the first thickness.

[0024] In one example, the sheet portion may be formed by a plurality of first rods and second rods crossing each other in a grid shape.

[0025] In one example, the first rod and the second rod may be respectively formed with concave marks at intersections where the first rod and the second rod intersect each other, so that the first rod and the second rod overlap each other.

[0026] In addition, the present invention provides a large-size mask assembly for OLED evaporation, which includes: the large-size mask sheet mentioned above; and a mask frame for bonding the large-size mask sheet.

[0027] In one example, the large-sized mask assembly described above can be applied to manufacturing large-sized displays of 1,500 mm×1,850 mm (sixth generation) or more.

[0028] Effects of the Invention

[0029] According to the present invention, by joining a plurality of mask sheets manufactured using original sheets or individual mask rods to increase the size, it is possible to provide an OLED evaporation mask sheet and a mask assembly including the same, which are suitable for manufacturing large-size displays of 1,500 mm×1,850 mm (sixth generation) or more that were previously difficult to manufacture using Invar original sheets.

[0030] Furthermore, according to the present invention, when the sheet is enlarged according to the joint between the sheets, the welding parts can be minimized while effectively absorbing the stress caused by welding and / or tension. Therefore, when a large-sized sheet is manufactured, the wrinkles of the sheet can be minimized, the sheet can be sufficiently close to the substrate, and the scratches when in contact with the substrate can be minimized. In addition, excellent unit positioning accuracy can be ensured and product defects can be minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a diagram showing how a large-sized sheet is realized by attaching a connection support structure to the lower ends of the joints of two mask sheets according to the prior art, that is, a diagram showing how a dead zone occurs due to the connection support structure.

[0032] Figure 2 and Figure 3 are diagrams showing the bonding between the lips of a large-size mask sheet for OLED evaporation according to an embodiment of the present invention, Figure 2 The case where the space between the lips is used as the cell opening is shown. Figure 3 A case where the space between the lips is used as a pseudo hole is shown.

[0033] Figure 4 FIG. 1 is a side cross-sectional view showing a lip portion of a large-size mask sheet for OLED evaporation according to an embodiment of the present invention where lips are joined together, as an example. Figure 4 of Part of the figure shows the case of joining by welding. As another example, Figure 4 of Some of them are diagrams showing the case of joining by adding a rod.

[0034] Figure 5 The diagram shows a process of bonding a large-size mask sheet for OLED evaporation according to an embodiment of the present invention to a mask frame after the large-size mask sheet is stretched.

[0035] Figure 6 A plan view showing a large-size mask sheet for OLED evaporation according to an embodiment of the present invention is shown. Figure 7 To show Figure 6 The enlarged view of part a is a view including the second pseudo hole.

[0036] Figure 8 To illustrate the preparation of a large-size mask sheet for OLED evaporation according to an embodiment of the present invention in the form of an original sheet. and the case where individual rods are crossed and prepared The picture, Fig. 9 A diagram showing that in the intersection of a mask sheet formed by individual rods, recesses are formed on each rod in order to minimize the step difference. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person skilled in the art can easily implement the present invention. However, the present invention can be implemented in a variety of different embodiments and is not limited to the embodiments disclosed below. In addition, in order to clearly disclose the present invention in the accompanying drawings, parts not related to the present invention are omitted, and the same or similar reference numerals are used for the same or similar components in the accompanying drawings.

[0038] The objects and effects of the present invention can be naturally understood or become more clear through the following description, and the objects and effects of the present invention are not limited to the following description.

[0039] The purpose, features and advantages of the present invention will become more clear from the following detailed description. In addition, in the process of describing the present invention, if it is considered that the detailed description of the related known technology composition or function will confuse the gist of the present invention, its detailed description may be omitted. Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

[0040] Today, the demand for large-size OLED panels is increasing significantly to meet the needs of various designs and the trend of larger displays. On the other hand, the maximum size of the Invar mask sheet stock currently available is only about 1100mm wide, so it is difficult to use the mask sheet stock to manufacture large-size OLED mask components.

[0041] On the other hand, Figure 1 As shown, there has been an example in the past of enlarging the size of the mask sheet by providing a connecting support member Sh at the lower end of the joint when joining mask sheets. However, when attempting to enlarge the sheet in the manner as described above, the stress caused by welding is too great due to the large welding interval, causing wrinkles in the sheet, making it difficult to fit tightly to the substrate and ensuring overall unit position accuracy.

[0042] In addition, the joint portion becomes a dead area that is discarded, making it difficult to fully utilize the sheet material and to ensure sufficient joint durability. Therefore, the present inventors have studied a method for minimizing the welding interval while ensuring sufficient durability and effectively absorbing the stress generated during welding and the stress generated during the subsequent stretching and joining process, thereby effectively achieving a large size of the mask sheet by using an original sheet or a rod, and have completed the present invention.

[0043] Hereinafter, a mask sheet for OLED evaporation and a mask assembly including the same according to the present invention will be described in more detail with reference to the accompanying drawings.

[0044] Large size mask

[0045] The large-sized mask sheet for OLED evaporation according to an embodiment of the present invention is a large-sized mask sheet formed by bonding a plurality of sheet sections 100 including one or more first unit openings 101, wherein the sheet sections 100 are bonded at bonding regions 151, and the bonding regions 151 of the sheet sections 100 can be bonded to each other by protruding lips 150. The large-sized mask sheet formed as described above is subjected to a stretching process ( Figure 5 ) is stretched, fixed and joined to the mask frame 300 to form a mask assembly. Hereinafter, each structure and manufacturing process will be described in detail with reference to the accompanying drawings.

[0046] First, refer to Figure 2 and Figure 3 , the sheet portion 100 is arranged in a plurality, and the bonding areas 151 thereof are bonded to each other, thereby achieving a large size. Specifically, the sheet portion 100 may be formed with one or more first unit openings 101, and the organic compound generated from the evaporation source passes through the above-mentioned first unit openings 101, and, considering the size of the evaporation object or the evaporation area, etc., it may be used in the form of bonding at least two sets of sheet portions 100, 100', or, when necessary, it may be used in the form of bonding more than three sheet portions 100, 100', 100''. On the other hand, the portion where the sheet portions 100 are bonded is defined as a bonding area 151, and the bonding area 151 may be an edge of the sheet portion 100.

[0047] For example, when the sheet portion 100 is arranged only in the horizontal direction to achieve large size, the peripheral sheet portion 100 may be formed with a bonding area 151 in the inner direction, and in the case where the sheet portion 100 is located on the inner side, the bonding areas 151 may be formed on both sides. In addition, when the sheet portion 100 is large-sized not only in the column in the horizontal direction but also in the row direction, the bonding areas 151 must be formed in the common areas where the sheet portions 100 positioned parallel to each other as described above are bonded. On the other hand, the mask sheet that has been large-sized as described above is stretched through a stretching process, fixed and bonded to the mask frame 300, thereby being completed as a mask assembly, so that it can be used for a vapor deposition process such as forming an organic common layer. On the other hand, after the above-mentioned stretching and bonding process, the unit opening portion may be further subjected to a post-processing process using a femtosecond laser or the like, so that the unit positioning accuracy can be further ensured.

[0048] On the other hand, refer to Figure 8 and Fig. 9 The sheet portion 100 may be provided as an original sheet, and a plurality of first unit openings 101 ( Figure 8 of Alternatively, the individual rods 110 and 111 may be formed by crossing each other in a grid shape ( Figure 8 of Specifically, when the sheet portion 100 is formed in a raw sheet form, the sheet portion 100 may be manufactured by a process of forming a plurality of first unit opening portions 101 in the sheet portion 100 having one wide surface shape and forming the lip 150 in the bonding area 151 .

[0049] On the other hand, when the sheet is formed in a rod shape, a plurality of thin rod-shaped transverse first rods 110 and longitudinal second rods 111 are prepared and positioned crosswise and overlappingly in a grid shape. Due to the grid shape, the first unit opening 101 equivalent to the grid is arranged inside, and the rods protrude from the outer peripheral surface, so that the lip edge 150 can be naturally formed.

[0050] On the other hand, when the sheet portion 100 is formed by a rod, the lip 150 is protruded on all peripheral surfaces, but the lip 150 in the bonding area 151 is left for bonding between the lips 150, and the rod length can be controlled on the peripheral surface other than that so that the lip 150 does not protrude, or it can also be used as a stretching sheet for the stretching process, or it can also be used as a fixing sheet fixed and bonded to the mask frame 300 after the stretching process.

[0051] On the other hand, when the sheet portion 100 is formed in a rod shape, if the thickness of the sheet portion 100 to be manufactured is the first thickness H1, the rod should have the first thickness H1, and the intersection portion where the rods overlap each other in a grid shape should also have the first thickness H1, so as to prevent the step difference and ensure close contact with the substrate. Therefore, in the intersection portion where the rods overlap and cross each other, the concave engraving 112 is formed on each rod so that the total thickness thereof is the first thickness H1 when the rods cross and join. At this time, the two rods at the intersection portion can be joined to each other by welding or a joining method using a bonding agent or the like.

[0052] Return to reference Figures 2 to 4 In order to engage between the lips 150, the sheet portion 100 may form the lips 150 only in the engagement area 151. The lips 150 have an extended rod shape protruding in the direction facing the engagement areas 151 that are mutually combined in the respective engagement areas 151 of the sheet portion 100, and may have a protruding sheet shape. These lips 150 may be arranged in a plurality along the longitudinal direction of the engagement area 151. In order to engage the lips 150 and the lips 150 of the sheet portion 100 to be engaged with each other, the width, position or number of the lips 150 should be realized to correspond to the width, position or number of the relative lips 150 to be engaged. When the mutual engagement between the lips 150 is performed as described above, the space between the lips 150 and the lips 150 may be opened.

[0053] Specifically, when the lips 150 are engaged with each other as described above, the space between the lips 150 is opened, and the opening can be used as the second unit opening 102 ( Figure 2 ), or may be used as a first dummy hole 200 ( Figure 3 ).

[0054] On the other hand, in the prior art, when the mask sheets are bonded, the support structure Sh corresponding to the bonding area 151 is attached to the lower end of the bonding area and welded, however, in this case, a dead zone is formed, and the interval and area to be welded are wide, so it is likely that deformation such as wrinkling, warping or sagging will occur in the sheet. On the other hand, when the lips 150 are bonded to each other as in the present invention, the welding interval and area are limited, so that the sheet deformation as described above can be significantly suppressed, and at the same time, the space between the lips 150 and the lips 150 can be ensured, and the above space can be used as the second unit opening 102 to optimize the sheet utilization, or can be used as the first pseudo hole 200 to minimize the sheet deformation by absorbing the stress generated during stretching and bonding.

[0055] On the other hand, refer to Figure 4 When the lips 150 are joined, the lips 150 can be joined by welding or by joining metals. At this time, the lips 150 can be joined to each other in the form of overlapping and joining the lips 150 of the joining area to be joined to each other, and the thickness H2 after joining can be set to be less than or equal to the thickness H1 of the sheet portion 100. For example, when the above welding is performed by using a laser spot welding method, a welding protrusion may be formed after welding, and if the thickness H2 after the above joining is the same as the thickness H1 of the sheet portion 100, scratches may occur on the substrate due to the above welding protrusion, and it also causes a problem of difficulty in close contact with the substrate.

[0056] Therefore, when the thickness of the sheet portion 100 is a predetermined first thickness H1, if the portion where the lips 150 overlap each other is defined as a bonding area 151, the thickness of the portion where each bonding area 151 of the lips 150 overlaps and bonds is set to a second thickness H2 that is less than or equal to the first thickness H1 of the sheet portion 100. In addition, in the case of bonding using a bonding agent or the like, the thickness of the bonding portion may be set to be less than or equal to the first thickness H1 in consideration of the thickness of the bonding agent Sp. For example, Figure 4 In Part is a side cross-sectional view schematically showing the process of joining the lips by welding, Figure 4 In Part of the figure is a side sectional view schematically showing the welding process by adding an auxiliary rod.

[0057] On the other hand, refer to Figure 6 and Figure 7 , a second dummy hole 210 may be provided as a structure to minimize deformation of the bonding area 151 during the bonding process between the lip 150 or the stretching and frame bonding process. The second dummy hole 210 may be formed at the lip 150. In detail, the second dummy hole 210 may be a fine opening adjacent to the bonding area 151 of the lip 150 and spaced apart from each other by a predetermined distance. The second dummy hole 210 absorbs the deformation caused by the bonding process ( Figure 5 ) or the deformation of the sheet caused by the tension and / or stress generated in the joining process between the sheets by welding, etc., thereby having the effect of preventing the sheet portion 100 from wrinkling. On the other hand, the second dummy holes 210 can be arranged at a predetermined distance in the joining area 151 of the lip edge 150, but if necessary, they can be arranged along the edge of the first dummy hole 200 or the second unit opening portion as the space between the lips 150.

[0058] Large size mask components

[0059] According to another embodiment of the present invention, a large-size mask assembly for OLED evaporation may include the large-size mask sheet and a mask frame 300 for bonding the large-size mask sheet. On the other hand, the large-size mask sheet or the mask frame may be made of Invar-36 alloy or stainless steel (SUS420).

[0060] On the other hand, after performing the stretching process and the bonding process to the mask frame, the mask sheet can be manufactured into a mask assembly, and after the bonding process, post-processing such as laser trimming can be further performed to further improve the unit position accuracy. On the other hand, the laser trimming post-processing can be performed on the unit opening using a processing device such as a picosecond laser or a femtosecond laser, which is a microwave laser.

[0061] As described above, the mask sheet and mask assembly according to the present invention are enlarged in size by joining multiple mask sheets manufactured using original sheets or individual mask rods, and can therefore be suitable for manufacturing large-size displays of 1,500mm×1,850mm (sixth generation) or above, which were previously difficult to manufacture using original sheets of Invar plate materials.

[0062] In addition, the mask sheet and mask assembly according to the present invention can minimize the welding parts when the sheet is enlarged by joining the sheets, and effectively absorb the stress caused by welding and / or tension. Therefore, when manufacturing large-sized sheets, the wrinkles of the sheet can be minimized, and the sheet can be fully attached to the substrate, and the scratches can be minimized when contacting the substrate. In addition, excellent unit positioning accuracy can be ensured and product defects can be minimized.

[0063] The preferred embodiments of the present invention described above are disclosed for illustration purposes, and a person skilled in the art may make various modifications, changes and additions within the concept and scope of the present invention, and these modifications, changes and additions shall be deemed to be included in the scope of the appended claims. A person skilled in the art may make various substitutions, deformations and changes within the scope of the technical spirit of the present invention, so the present invention is not limited to the above embodiments and drawings.

[0064] Description of Reference Numerals

[0065] 100: Sheet material department

[0066] 101: First unit opening

[0067] 102: Second unit opening

[0068] 110: First leg

[0069] 111: Second runner

[0070] 150: Lip

[0071] 151: Junction area

[0072] 200: First pseudo hole

[0073] 210: Second pseudo hole

[0074] 300: Mask frame

[0075] Sp: junction point

[0076] S: Auxiliary rod

[0077] Sh: Support structure

Claims

1. A large-size mask sheet for OLED evaporation, which is a large-size mask sheet formed by joining a plurality of sheet portions (100) including one or more first unit opening portions (101), characterized in that: The plurality of sheet portions (100) are joined to each other by joining between lips (150) protruding from the joining area (151).

2. The large-size mask sheet for OLED evaporation according to claim 1, characterized in that: The mask sheets are joined to each other by joining the lips (150) and then stretched.

3. The large-size mask sheet for OLED evaporation according to claim 1, characterized in that: The mask sheet has an open space between the lips (150) formed by the bonding between the lips (150).

4. The large-size mask sheet for OLED evaporation according to claim 3, characterized in that: The space between the lips (150) is the second unit opening (102).

5. The large-size mask sheet for OLED evaporation according to claim 3, characterized in that: The space between the lips (150) is a first pseudo hole (200) for absorbing tensile strain.

6. The large-size mask sheet for OLED evaporation according to claim 1, characterized in that: The joining between the lips (150) is performed by welding or joining between metals.

7. The large-size mask sheet for OLED evaporation according to claim 1, characterized in that: The invention comprises one or more second dummy holes (210) arranged at predetermined intervals in the joint area (151) of the lip edges (150) that are joined to each other.

8. The large-size mask sheet for OLED evaporation according to claim 1, characterized in that: The lip edge (150) has a first thickness (H1), the joining areas (151) of the lips (150) joined to each other overlap each other, and then the lips (150) are engraved to have a second thickness (H2) less than or equal to the first thickness (H1).

9. The large-size mask sheet for OLED evaporation according to claim 1, characterized in that: The sheet portion (100) is formed by a plurality of first rods (110) and second rods (111) intersecting in a grid shape.

10. The large-size mask sheet for OLED evaporation according to claim 9, characterized in that: The first rod (110) and the second rod (111) are respectively formed with concave engravings (112) at the intersections where they intersect each other, so that the first rod (110) and the second rod (111) overlap each other.

11. A large-size mask assembly for OLED evaporation, characterized in that: include: The large-size mask according to claim 1; and The mask frame (300) is used for joining the large-sized mask sheet.

12. The large-size mask assembly for OLED evaporation according to claim 11, characterized in that: The above-mentioned large-size mask assembly is applied to manufacture large-size displays of the sixth generation or above with a size of 1,500 mm×1,850 mm.

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