Manufacturing method of master mask assembly for 8th generation OLED open-type metal mask and the assembly manufactured by the method

Abstract

A method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask is provided. The method includes the following steps: preparing raw materials to cover the area on the 8th generation OLED where the image is formed, i.e., the effective display area; forming a preset first pattern in the effective display area of ​​the raw materials to create a master mask; forming a preset second pattern for the portion of the 8th generation OLED that the master mask cannot cover to create a dummy mask; using at least one welding method to first join the dummy mask and the master mask; and tensioning the joined master mask and dummy mask along the four sides of a support frame and then joining them a second time.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask and an assembly manufactured by the method. The method involves first joining a master mask and a dummy mask, and then secondarily joining the mask sheet to a frame while tensioning the mask sheet, thereby providing a method for manufacturing large-area assemblies. Background Technology

[0002] Currently, OLED displays are primarily manufactured using 6th generation equipment, employing 1500×1850mm glass substrates, with smartphone panels as the core component. In recent years, as the application of OLED technology has expanded to medium and large-sized devices such as laptops and monitors, the demand for larger substrates has continued to grow. 6th generation equipment suffers from low glass edge-grinding efficiency and production yield bottlenecks when producing large panels. Therefore, introducing 8th generation or higher processes has become inevitable to achieve high-efficiency, large-area production. Against this backdrop, developing 8th generation-based large-area OLED manufacturing technology capable of handling glass sizes of 2200×2500mm and above has become a core industry issue. In the 8th generation OLED manufacturing process, large-area organic material evaporation technology is one of the key technologies, and the core material for realizing this technology is Invar metal masks.

[0003] At this time, in order to overcome the supply limitations of the 8th generation masks, the industry has developed rod-shaped and sheet-joining methods as alternative solutions. Among the relevant prior art, Korean Patent No. 10-1579907 (announced on December 23, 2015) and No. 10-2591278 (announced on October 19, 2023) disclose the following structures: fabricating a mask sheet consisting of a mask frame and multiple mask rods with vapor deposition patterns, tensioning the multiple mask rods of the mask sheet, and joining the tensioned multiple mask rods to the mask frame to form a tensioned mask sheet, and forming alignment marks at predetermined positions on the tensioned mask sheet formed by the multiple mask rods joined to the mask frame; etching the entire lower side of the mask sheet to eliminate deformations such as curling of the mask sheet ribs and prevent sagging or upturning of the unit opening ends.

[0004] While the above two methods maximize the use of existing equipment and processes, they suffer from quality issues such as pattern distortion during tensioning, contamination at joints during cleaning, and defects caused by particle residue. Up to the 6th generation, the industry's mask manufacturing method involves providing Invar sheet coils with a width of less than 1040mm and a thickness of less than 0.2mm, etching the pattern, and then fixing it to a frame through tensioning and welding. However, producing 8th generation and above large-area panels requires master Invar materials with a width of more than 1400mm. Currently, the steel manufacturing infrastructure capable of stably producing such wide Invar coils is extremely limited both domestically and internationally, requiring hundreds of billions of Korean won in equipment investment and advanced rolling and heat treatment technologies. Therefore, there is an urgent need to develop methods for manufacturing large-area masks. Summary of the Invention

[0005] One embodiment of the present invention provides a method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask: First, prepare raw materials that can only cover the effective display area where the 8th generation OLED image is formed; fabricate a master mask within the effective display area; first, join the master mask with a connected dummy mask; then, join the mask sheet containing the master mask and the dummy mask with a frame, thereby achieving the same effect as a master mask of 1400mm or more. However, the technical problem to be solved by this embodiment is not limited to the above, and may also include other technical problems.

[0006] As a technical means to achieve the above-mentioned technical problem, one embodiment of the present invention includes the following steps: preparing raw materials to cover the area on the 8th generation OLED where the image is formed, namely the active area; forming a preset first pattern in the active area of ​​the raw materials to create a main mask; forming a preset second pattern for the part of the 8th generation OLED that the main mask cannot cover to create a dummy mask; using at least one welding method to join the dummy mask and the main mask once; and tensioning the joined main mask and dummy mask along the four sides of the support frame (frame) and joining them a second time.

[0007] According to any of the technical solutions to the above-mentioned problems of the present invention, in order to manufacture a mother mask assembly for an 8th generation OLED open metal mask (OMM), a raw material with a thickness of less than 0.3 mm and a width of about 1300 mm can be used to form the required pattern in the effective display area to make a main mask. A dummy mask is made for the part with insufficient size and is firstly joined with the main mask. Then, the mask sheet is secondarily joined with the frame to finally achieve the same effect as a mother mask with a width of 1400 mm or more. Attached Figure Description

[0008] Figure 1 The figure illustrates a method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask according to an embodiment of the present invention.

[0009] Figure 2 For illustrative purposes Figure 1 A diagram of a single joining step in the manufacturing process.

[0010] Figure 3 For illustrative purposes Figure 1 A diagram of the secondary bonding step in the manufacturing method.

[0011] Figure 4 This is a diagram used to illustrate the finished product.

[0012] Figure 5a The diagram illustrates the dimensions of the master molds for each generation. Figure 5b This graph illustrates the changes in the number of discarded items (yield increase or decrease) due to differences in substrate size. Figure 5c The manufacturing process of OMM is shown. Figure 5d and Figure 5e The connection between the mask and the frame and the method of vapor deposition of organic materials are shown. Detailed Implementation

[0013] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings to facilitate implementation by those skilled in the art. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. For clarity, parts unrelated to the description are omitted from the drawings, and the same reference numerals are used for the same parts throughout the specification.

[0014] In this specification, the term "connected" to another component includes not only "direct connection" but also electrical connection with other components in between. Furthermore, the term "comprises" of a component should be understood to mean that, unless otherwise stated, other components are not excluded, but rather may be included, without pre-excluding the existence or additional possibility of one or more other features, figures, steps, operations, components, parts, or combinations thereof.

[0015] The terms "about" and "substantially" used in this specification are intended to indicate the inherent manufacturing and material tolerances of the stated values, to prevent misuse of absolute values ​​by improper users, and to aid in understanding the invention. The term "...step" used in this specification does not specifically refer to "steps for...".

[0016] In this specification, a "unit" includes a unit implemented by hardware, a unit implemented by software, and a unit implemented by the combination of software and hardware. Additionally, one unit can be implemented by two or more hardware components, and two or more units can also be implemented by one hardware component. Furthermore, a "unit" is not limited to the meaning of software or hardware, and can be configured in an addressable storage medium or configured to run on one or more processors. Therefore, for example, a "unit" includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, programs, subprograms, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided by each component and "unit" can be combined into fewer components and "units", or further separated into more components and "units". Moreover, it can also be implemented by running on one or more CPUs in a device or a secure multimedia card.

[0017] In this specification, some operations or functions described as being performed by a terminal, device, or equipment can be alternatively performed by a server connected thereto. Similarly, some operations or functions performed by a server can also be performed by a terminal, device, or equipment connected thereto.

[0018] In this specification, some operations or functions described as being mapped or matched with a terminal can be understood as mapping or matching with the terminal identification information, that is, the unique number or personal identification information of the terminal.

[0019] The present invention will be described in detail below with reference to the accompanying drawings.

[0020] Figure 1 A diagram for explaining a method of manufacturing a master mask assembly for an 8th generation OLED open metal mask according to an embodiment of the present invention. Figure 2 For explaining Figure 1 a diagram of the first bonding step in the manufacturing method of Figure 3 For explaining Figure 1 a diagram of the second bonding step in the manufacturing method of Figure 4 A diagram for explaining the finished product.

[0021] First, the terms to be described below are defined and explained.

[0022] <OMM (Open Metal Mask, open metal mask)> OMM (Optical Modeling) is a technology used in semiconductor manufacturing and microelectronics processes. Similar to traditional photolithography, it eliminates the need for photoresist, forming patterns directly through a metal mask. First, it eliminates the need for photoresist. Conventional photolithography requires applying photoresist followed by exposure and development processes to create patterns; OMM allows direct deposition or etching using a metal mask. Second, it is cost-effective and environmentally friendly. Eliminating the need for photoresist eliminates chemical processing (development, etching, and removal), reducing waste and shortening process time, thus combining environmental friendliness and economic efficiency. Third, it enables high-precision patterning. The use of a metal mask overcomes the resolution limitations of photoresist, allowing for high-resolution, fine patterning applicable to semiconductor and display processes. Furthermore, OMM technology can be used in wafer patterning in semiconductor manufacturing, micro-electro-mechanical systems (MEMS) manufacturing, and patterning for micro-LEDs and display panels.

[0023] <Master Mask> A mother mask refers to the original mask used in the metal mask manufacturing process of a display. In this context, the 8th generation open-face metal mask mother mask is the mother mask used in the 8th generation display process for OMM (metal mask) technology, such as TFT (Thin-Film Transistor) patterning. The mother mask serves as the base mask for creating multiple OMMs. It is primarily used in the manufacturing of OLED (Organic Light Emitting Diode) and LCD. (Refer to...) Figure 5a In display manufacturing, the 8th generation refers to a generation defined by the size of the glass substrate, specifically a 2200×2500mm display. The master mask first provides the basic pattern, a large mask containing the master pattern used to create OMMs (Original Machine Models). Multiple OMMs can be mass-produced, meaning multiple independent OMMs (display manufacturing masks) can be produced using the master mask. Simultaneously, it can form intricate patterns, directly creating precise metal patterns without photolithography, thereby reducing production costs.

[0024] <Invar> Invar is an alloy of iron (Fe) and nickel (Ni) with an extremely low coefficient of thermal expansion (CTE). It exhibits minimal deformation due to temperature changes, making it an essential material for forming precise patterns in semiconductor and display manufacturing processes.

[0025] <Ingersoll Coil> Invar steel coil refers to coils of Invar steel used in display panel manufacturing processes. It's used for creating OMMs (Open Metal Masks) in display manufacturing, allowing for precise machining of the metal patterns on the OMMs. Simultaneously, it maintains the flatness of the metal mask, improves pattern accuracy, and prevents deformation under high-temperature processes. Invar steel has virtually no thermal expansion, which is beneficial for maintaining precise patterns in high-temperature environments. Furthermore, this coil can be used in roll-to-roll processes, enabling continuous OMM production using Invar steel coils. Compared to traditional flat-panel processing, it is more suitable for large-scale mass production.

[0026] <Large-area OMM manufacturing process> Table 1 <Raw Material Preparation Steps> Based on the above basic concepts and manufacturing process, the master mask assembly manufacturing apparatus (not shown) can prepare raw materials covering the area on the 8th generation OLED where the image is formed, i.e., the active display area. For large-area 8th generation products (glass size 2200×2500mm), the optimal approach is to use raw materials with a width of 1400mm or more. However, due to supply limitations, 6th generation 1040mm raw materials are currently used for splicing. Furthermore, it is currently impossible to manufacture Invar raw materials with a thickness of less than 0.3mm and a large width. Even if widened as much as possible, the limit is only about 1300mm, which cannot meet the minimum size required for 8th generation (1400mm or more).

[0027] From an effectiveness perspective, two-segment and three-segment methods are currently under research. However, these methods can only perform unilateral tensioning in two directions, which may lead to localized inward contraction during tensioning. Even with compensation during the design phase, there are still challenges to overcome, such as uneven tensioning across different parts and decreased accuracy due to variations in opening dimensions. Furthermore, using two-segment or three-segment methods requires shielding the tensioning welding at the connection points, presenting numerous difficulties in terms of cost and quality. Solving these problems in one go is the core of this invention.

[0028] Therefore, in one embodiment of the present invention, a maximum maximum size is used, approximately 1300mm of raw material. Here, 1300mm is only the minimum size to cover the effective display area of ​​the 8.6th generation, and is not a limitation. For example, if the actual effective display area is 1250mm, then including the 5mm welding portion, a size of 1260mm or more would meet the requirements.

[0029] <Master Mask Fabrication Steps> A master mask assembly manufacturing apparatus (not shown) can form a preset first pattern within the effective display area of ​​the raw material to create a main mask. First, using generation 8.6 (glass size 2620 × 2290 mm) as a reference, the method of halving the glass and then depositing organic materials is employed. In this case, the smallest effective area where the organic material is actually deposited onto the glass is called the effective display area. Its size is approximately (1250–1290 mm) × (2250–2280 mm). In this situation, the desired pattern can be first formed on an Invar raw material approximately 1300 mm wide and slightly larger than the effective display area, covering the effective display area, thereby creating the main mask.

[0030] Here, "pattern" refers to the array of micro-holes (slits, openings) formed on a metal mask to create a specific shape during the OLED evaporation process. This pattern ensures that the organic material to be deposited (emitting layer, electrodes, etc.) is coated only at designated locations, determining the performance and resolution of the OLED element. This pattern is a crucial structure for forming the pixels of an OLED element, and its accuracy and precision directly affect OLED quality. The pattern is used to deposit organic material onto each pixel (R, G, B sub-pixels) of the OLED element. The size and alignment accuracy of the mask pattern are core to achieving 4K and 8K high resolution, while minimizing mask deformation and evaporation errors improves yield.

[0031] Table 2 One embodiment of the present invention provides a technique for producing 8.6th generation master OMMs.

[0032] <Steps for Creating a Virtual Mask> A master mask assembly manufacturing apparatus (not shown) forms a preset second pattern to create a dummy mask for the portion of the 8th generation OLED that the master mask cannot cover. In this case, assuming the effective display area width is 1250mm and the raw material width is 1300mm, it cannot completely cover half of the 2620mm width of the 8.6th generation glass, i.e., 1310mm. This shortfall (1310mm - 1300mm = 10mm) is made up by the dummy mask. Although numerically less than 10mm, this shortfall can be covered in four directions around the master mask within the effective display area, allowing for flexible shape and size variations. Here, the dummy mask refers to a non-active mask used in semiconductor, display (OLED, LCD), MEMS, PCB, and other manufacturing processes, primarily for protecting specific areas in the production process or for testing and calibration of process equipment.

[0033] At this point, the second pattern may include: half etching at the joint to ensure the strength of the joint between the master mask and the dummy mask; full etching to achieve gas venting and alignment at the through-parts of the dummy mask; and half etching to prevent warping at the non-through-parts of the dummy mask. However, it is not limited to the above, and reasonable methods not listed are not excluded.

[0034] Here, the width of the dummy mask can be 20mm or more, for example, 20mm to 200mm, but is not limited to this range.

[0035] <One-step bonding process> Reference Figure 2 The master mask assembly manufacturing apparatus (not shown) uses at least one welding method to join the dummy mask and the master mask in a single operation. Through this joining, a structure is formed as shown... Figure 2 The mask sheet S1100 shown is a combination of a [main mask + dummy mask]. Here, the welding method can be laser welding, but other welding methods can also be used; it is not limited to one method.

[0036] <Secondary Joining Steps> Reference Figure 3 The master mask assembly manufacturing device (not shown) can tension the joined master mask and dummy mask along the four sides of the support frame (up, down, left, and right), while simultaneously performing secondary joining S1200~S1300. The metal mask is fixed to the frame, and the mask sheet can be tightened by applying tension to both sides through the frame. The reason for tensioning at this time is that if the thin sheet or metal plate mask sheet is not tightened, it is difficult to maintain flatness, and problems such as bulging and denting are likely to occur, making it impossible to ensure uniform thickness. Therefore, after the processed mask sheet is fixed to the frame, it is tensioned to keep it in a flat state without sagging.

[0037] Alternatively, the dummy mask can be first combined with the 1300mm raw material to form the required master mask material, and then patterned at once (master mask patterning + dummy mask patterning) to create the required master mask.

[0038] Furthermore, after tensioning and secondary joining the joined master mask and dummy mask along the four sides of the support frame (top, bottom, left, and right), the master mask assembly manufacturing device (not shown) can cut off the overlapping portion S1400 between the secondary joined dummy mask and the support frame. After all steps are completed, the result is as follows: Figure 4 The finished product is shown. In addition, the master mask assembly manufacturing apparatus (not shown) can add an alignment step between the master mask and the dummy mask before the step of joining the dummy mask and the master mask at one time using a laser.

[0039] Figure 5a The diagram illustrates the dimensions of the master molds for each generation. Figure 5b This graph illustrates the changes in the number of discarded items (yield increase or decrease) due to differences in substrate size. Figure 5c The manufacturing process of OMM is shown. Figure 5d and Figure 5e The connection between the mask and the frame and the method of vapor deposition of organic materials are shown. Figures 5a to 5e The accompanying drawings are not of a specific embodiment of the present invention, but are used borrowed images from various companies to illustrate relevant concepts and processes. Figure 5a and Figure 5b For Samsung monitors, Figure 5c For Fengyuan Precision, Figure 5d For Samsung displays, Figure 5e (For PIMS Company).

[0040] As described above, an embodiment of the present invention describes the OMM manufacturing process as follows: After fabricating a main mask and a dummy mask, the main mask and the dummy mask are welded together once. The welded mask is then tensioned and welded a second time on a supporting frame. The tensioned and welded mask is then inspected. If the main mask width is 1300mm or more, although it can cover the actual required effective display area (1250mm~1290mm), during tensioning, a portion of the mask needs to be clamped by a tensioning machine to adhere to the frame, and this portion needs to have a minimum length to ensure no interference with the frame. This length varies depending on the frame and tensioning machine design, but it must be at least 20mm on one side. Therefore, a width of only 1300mm is insufficient to manufacture the 8.6th generation OMM (2620×2290). However, using the manufacturing method of an embodiment of the present invention, a dummy mask with a width of at least 50mm is fabricated and welded, which can provide coverage. Furthermore, in order to maintain tension warpage and uniformity when creating a dummy mask, more stable tension can be achieved by forming multiple patterns and reflecting them in the design.

[0041] pass Figure 1 The master mask assembly manufacturing method described in one embodiment can also be implemented as a recording medium containing computer-executable instructions, such as a computer-executable application program or program module. The computer-readable medium can be any available medium accessible by a computer, including volatile and non-volatile media, and removable and non-removable media. Furthermore, the computer-readable medium also includes a computer storage medium, i.e., a volatile and non-volatile, removable and non-removable medium implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data.

[0042] The master mask assembly manufacturing method of one embodiment of the present invention can be executed by an application pre-installed on the terminal (including programs included in the platform or operating system natively mounted on the terminal), or by an application (i.e., a program) directly installed to the main terminal by the user through an application store server, application server, or web server related to the application server. Accordingly, the master mask assembly manufacturing method of one embodiment of the present invention can realize applications (i.e., programs) pre-installed on the terminal or directly installed by the user, and recorded in a computer-readable recording medium such as the terminal.

[0043] The above description of the present invention is for illustrative purposes only. Those skilled in the art should understand that it can be easily modified into other specific forms without changing the technical concept or essential features of the present invention. Therefore, the above embodiments should be understood as exemplary and not restrictive in all respects. For example, the constituent elements described in a single form may be implemented separately, and similarly, the constituent elements described in a separate form may be implemented in combination.

[0044] The scope of this invention is defined by the appended claims, rather than by the detailed description above. All changes and modifications within the meaning, scope, and equivalent concepts of the claims shall fall within the protection scope of this invention.

Claims

1. A method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask, characterized in that, Includes the following steps: Raw materials are prepared to cover the area on the 8th generation OLED where the image is formed, i.e., the effective display area; A preset first pattern is formed within the effective display area of ​​the raw material to create a master mask; A preset second pattern is formed for the portion of the 8th generation OLED that cannot be covered by the main mask, thus creating a dummy mask; The dummy mask and the main mask are joined together in one step using at least one welding method; as well as The main mask and the dummy mask, after being joined, are tensioned along the four sides of the support frame (up, down, left, and right) and then joined together a second time.

2. The method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask according to claim 1, characterized in that, The raw material is an alloy of iron (Fe) and nickel (Ni), namely Invar.

3. The method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask according to claim 1, characterized in that, The second pattern includes: To ensure the strength of the joint between the main mask and the dummy mask, a half-etch is performed at the joint. To achieve gas discharge and alignment, full etching is performed at the through-section of the dummy mask; and To prevent the dummy mask from warping, a semi-etching is performed on the non-through portion of the dummy mask.

4. The method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask according to claim 1, characterized in that, After tensioning and secondary joining the main mask and dummy mask along the four sides of the support frame (top, bottom, left, and right), the process also includes: The step of cutting off the overlapping portion between the dummy mask and the support frame after secondary joining.

5. The method for manufacturing a master mask assembly for an 8th generation OLED open-type metal mask according to claim 1, characterized in that, Before the step of joining the dummy mask and the master mask in one operation using at least one welding method, the method further includes: The step of aligning the master mask with the dummy mask.

6. A master mask assembly for an 8th generation OLED open-type metal mask, characterized in that, The master mask assembly is manufactured by the method for manufacturing a master mask assembly for an 8th generation OLED open metal mask as described in any one of claims 1 to 5.

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