Method for repairing mask assembly for manufacturing display panel

Abstract

The present invention relates to a method for repairing a mask assembly for manufacturing a display panel. In one embodiment, the method for repairing the mask assembly comprises a mask frame having a hollow portion formed on its inner side and a plurality of support sticks bonded to the upper surface of the mask frame to form a predetermined pattern. The method further comprises the steps of: removing the support sticks from the mask frame when the height of the mask frame is reduced below a reference value due to damage; forming a coating layer by low-temperature spraying nickel steel powder onto the portion of the mask frame from which the support sticks have been removed; and bonding the support sticks onto the coating layer.

Description

Technology Field

[0001] The present invention relates to a method for repairing a mask assembly for manufacturing a display panel. Background Technology

[0003] Recently, OLEDs (Organic Light-Emitting Diodes) are being used in display devices such as televisions, PCs, various smart devices, and vehicle instrument panels.

[0004] OLEDs are manufactured through a thin-film process that stacks and patterns multiple thin-film layers, such as electrode layers, organic light-emitting layers, and insulating films. This thin-film process is carried out using masks equipped with corresponding patterns, and is performed using chemical vapor deposition (CVD), sputtering, ion plating, and evaporation.

[0005] Meanwhile, during OLED manufacturing, the above mask assembly is used to deposit an organic material (luminescent organic material) on an OLED display substrate. The mask assembly can guide the luminescent organic material to be deposited to pass through a hole formed in the mask and be deposited at a desired location on the substrate. In this case, the mask assembly can be formed by crossing a plurality of mask sticks on a mask frame and then bonding them to the frame.

[0006] The mask frame is a frame structure in the form of a picture frame and may be provided to stably maintain the shape of the mask assembly. The mask stick is in the form of a metal strip or stick, and a mask pattern to be used during deposition may be formed thereon. The mask pattern may include unit pattern portions corresponding to the shape and number of fine RGB pixels to be formed within each OLED display on the substrate.

[0007] The mask stick and mask frame of the mask assembly are manufactured using metals with a very low coefficient of thermal expansion with temperature, such as Invar-36 Alloy. Meanwhile, when manufacturing an OLED display panel by depositing organic materials multiple times using the mask assembly, contaminated or damaged mask sticks are removed from the mask frame, and new mask sticks are mounted and fixed to the mask frame by methods such as welding before being used in the display manufacturing process.

[0008] At this time, during the process of replacing the mask stick, the thickness of the part of the mask frame where the mask stick is welded (fixed) gradually decreases. Additionally, when the thickness of the mask frame decreases below a predetermined value, it is replaced with a new mask frame. However, since Invar alloy material is expensive, the replacement cost increases, which raises the production cost of the OLED display, and research is currently underway to minimize this.

[0009] The background technology related to the present invention is disclosed in Korean Registered Patent Publication No. 10-2193044 (published Dec. 18, 2020, Title of Invention: Metal Mask Manufacturing System and Method). The problem to be solved

[0011] One objective of the present invention is to provide a method for repairing a mask assembly for manufacturing a display panel that prevents wear of the mask frame when replacing the mask stick, thereby providing excellent effects in improving the durability and lifespan of the mask assembly.

[0012] Another objective of the present invention is to provide a method for repairing a mask assembly for manufacturing a display panel that enables the formation of a coating layer only on the contact area between the mask stick and the mask frame, thereby providing excellent cost-saving effects and economic efficiency.

[0013] Another objective of the present invention is to provide a method for repairing a mask assembly for manufacturing a display panel that has excellent durability, density, and adhesion to the mask frame of the coating layer. means of solving the problem

[0015] One aspect of the present invention relates to a method for repairing a mask assembly for manufacturing a display panel. In one embodiment, the method for repairing the mask assembly comprises a mask frame having a hollow portion formed on its inner side and a plurality of support sticks bonded to the upper surface of the mask frame to form a predetermined pattern. The method further comprises the steps of: removing the support sticks from the mask frame when the height of the mask frame is reduced below a reference value due to damage to the mask frame; forming a coating layer by low-temperature spraying nickel steel powder onto the portion of the mask frame from which the support sticks have been removed; and bonding the support sticks onto the coating layer.

[0016] In one embodiment, the low-temperature spraying can be performed by introducing the nickel steel powder into a spray nozzle and using a compressed gas with a temperature of 1100°C or lower and a pressure of 7.5 MPa or lower into the spray nozzle to accelerate the nickel steel powder into a supersonic jet of 300 to 1500 m / s and spray it onto the mask frame.

[0017] In one embodiment, the mask frame and the support stick may each comprise a nickel steel alloy.

[0018] In one embodiment, the coating layer may be formed by drying the nickel steel powder at 60 to 100°C after low-temperature spraying.

[0019] In one embodiment, the mask frame comprises a base portion; and a protrusion formed along the inner edge of the base portion; and a coating layer is formed on the surface of the protrusion so that the support stick can be bonded.

[0020] In one embodiment, the protrusion may be formed at an angle with respect to the normal direction of the base portion with respect to the cross-section of the mask frame.

[0021] In one embodiment, when forming the coating layer, the nickel steel powder can be sprayed by setting the spray nozzle relative to the surface of the protrusion at an angle of 30 to 65˚.

[0022] In one embodiment, the coating layer may be formed with a thickness of 0.05 to 5 mm.

[0023] In one embodiment, the support stick can be joined through laser welding. Effects of the invention

[0025] When the method for repairing a mask assembly for manufacturing a display panel according to the present invention is applied, the wear of the mask frame is prevented when replacing the mask stick, thereby providing excellent effects in improving the durability and lifespan of the mask assembly. Additionally, since a coating layer can be formed only on the contact area between the mask stick and the mask frame, it provides excellent cost reduction and economic efficiency, and the durability, density, and adhesion of the coating layer to the mask frame can be excellent. Brief explanation of the drawing

[0027] FIG. 1 schematically illustrates a method for repairing a mask assembly according to one embodiment of the present invention. FIG. 2 shows a mask assembly for manufacturing a display panel repaired according to one embodiment of the present invention. FIG. 3 shows a repaired mask assembly according to another embodiment of the present invention. Figure 4 shows a cross-section in the A-A' direction of the repaired mask assembly. FIG. 5 schematically illustrates the process of forming a coating layer according to another embodiment of the present invention. Specific details for implementing the invention

[0028] In describing the present invention, if it is determined that a detailed description of related known technologies or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0029] Furthermore, the terms described below are defined in consideration of their functions in the present invention; since these may vary depending on the intentions or practices of the user or operator, their definitions should be based on the content throughout this specification describing the present invention.

[0031] Repair method for mask assembly used in display panel manufacturing

[0032] One aspect of the present invention relates to a method for repairing a mask assembly for manufacturing a display panel. FIG. 1 schematically illustrates a method for repairing a mask assembly according to one embodiment of the present invention, and FIG. 2 illustrates a mask assembly for manufacturing a display panel repaired according to one embodiment of the present invention.

[0033] Referring to FIGS. 1 and 2 above, the present invention relates to a method for repairing a mask assembly (1000) for manufacturing a display panel, comprising a mask frame (100) having a hollow portion (101) formed on the inside and a plurality of support sticks (110) bonded to the upper surface of the mask frame (100) to form a predetermined pattern.

[0034] A method for repairing the mask assembly in one sphere comprises: (S10) removing a support stick from the mask frame when the mask frame is damaged and its height decreases below a reference value; (S20) forming a coating layer by low-temperature spraying nickel steel powder onto the portion of the mask frame from which the support stick was removed; and (S30) bonding the support stick onto the coating layer.

[0035] The above mask assembly can be used in a process for manufacturing a display panel, such as an OLED, by depositing an organic material. At this time, the contaminated and damaged mask stick (110) is removed from the mask frame (100) during the organic material deposition process, and a new mask stick (110) is bonded to the upper surface of the mask frame (100) to be used in the display manufacturing process.

[0036] Referring to Figure 1(a) above, in order to prevent defects and ensure stability when depositing organic material during the manufacture of a display panel, the height (α) of the mask frame (100) must be maintained above a reference value (β).

[0037] However, as shown in FIG. 1(b) above, during the process of replacing the mask stick (110) multiple times, the height of the part of the mask frame (100) where the mask stick (110) is welded (fixed) gradually decreases. Alternatively, the height may decrease if the mask frame (100) is damaged during the display panel manufacturing process.

[0038] Conventionally, when a mask frame (100) is damaged and its height (α) decreases below a standard value (β), it is replaced with a new mask frame. However, in the present invention, as shown in Fig. 1(c), nickel steel powder is sprayed at a low temperature onto the portion of the mask frame (100) where the support stick has been removed to form a coating layer (120). When the coating layer is formed, the mask frame replacement cycle is extended and costs are reduced, which can be economically efficient.

[0039] For example, the height reference value (β) of the above mask frame may be 1 to 50 mm.

[0040] Referring to the above Fig. 1(d), after the coating layer (120) is formed, a support stick (110) is bonded onto the coating layer (120).

[0041] Referring to FIG. 2 above, the repaired mask assembly (1000) has a coating layer (120) formed along the inner edge of the upper surface of the mask frame (100), and a support stick (110) can be bonded on the coating layer (120).

[0042] In one embodiment, the cold spraying can be performed by introducing the nickel steel powder into a spray nozzle and using a compressed gas with a temperature of 1100°C or lower and a pressure of 7.5 MPa or lower into the spray nozzle to accelerate the nickel steel powder into a supersonic jet of 300 to 1500 m / s and spray it onto the mask frame.

[0043] Under the above conditions, the porosity of the coating layer is minimized to ensure excellent structural density, as well as excellent mechanical strength such as hardness and durability and adhesion to the mask frame. For example, the compressed gas may include one or more of helium (He), nitrogen (N2), and air.

[0044] The nickel steel powder may contain nickel (Ni) and iron (Fe). For example, the nickel steel powder may contain 30 to 40 weight percent nickel (Ni) and 60 to 70 weight percent iron (Fe). Under these conditions, the coefficient of thermal expansion of the coating layer is minimized to minimize dimensional changes due to temperature changes, thereby minimizing the defect rate during the manufacture of display panels. For example, the nickel steel powder may contain an Invar alloy such as Invar-36.

[0045] In one embodiment, the low-temperature spraying can be performed using compressed gas at a temperature of 700 to 1100°C and a pressure of 1.5 to 7.5 MPa, with a stand-off distance (SOD) of 5 to 50 mm between spray nozzles, a gas flow rate of 600 to 3,000 SLM, and a feed rate of 2 to 5 kg / Hr for raw material (nickel steel powder). Under these conditions, a coating layer is easily formed, and the porosity is minimized to ensure excellent structural density, as well as excellent mechanical properties of the coating layer and adhesion to the mask frame.

[0046] In one embodiment, the coating layer may be formed by drying the nickel steel powder at 60 to 100°C after low-temperature spraying. Under these conditions, the porosity of the coating layer is minimized to ensure excellent structural density, and the mechanical properties of the coating layer and adhesion to the mask frame may be excellent.

[0047] In one embodiment, the coating layer may have a hardness of 150 to 300 Hv. Under these conditions, it has excellent durability and can prevent defects in the display panel when organic material is deposited.

[0048] In one embodiment, the mask frame and the support stick may each comprise a nickel steel alloy. The nickel steel powder may comprise nickel (Ni) and iron (Fe). For example, the nickel steel powder may comprise 30 to 40 weight percent nickel (Ni) and 60 to 70 weight percent iron (Fe). Under these conditions, the coefficient of thermal expansion of the mask assembly is minimized to minimize dimensional changes due to temperature changes, thereby minimizing the defect rate during the manufacture of a display panel. For example, the nickel steel powder may comprise an Invar alloy such as Invar-36.

[0049] FIG. 3 shows a repaired mask assembly (2000) according to another embodiment of the present invention, and FIG. 4 shows a cross-section in the A-A' direction of the repaired mask assembly.

[0050] Referring to FIG. 3 above, the mask frame (100) includes a base portion (102); and a protrusion (104) formed along the inner edge of the base portion (102), and a coating layer (120) is formed on the surface of the protrusion (104) so ​​that a support stick (110) can be bonded.

[0051] Referring to FIG. 4 above, the protrusion (104) may be formed at an angle with respect to the normal direction of the base portion (102) with respect to the cross-section of the mask frame (100).

[0052] FIG. 5 schematically illustrates the process of forming a coating layer according to another embodiment of the present invention. Referring to FIG. 5, when forming the coating layer (120), the nickel steel powder can be sprayed by setting the surface reference spray nozzle (200) of the protrusion (104) at an angle (θ) of 30 to 65°. When forming the coating layer by spraying the nickel steel powder at an angle (θ) of the normal direction reference spray nozzle (200) of the protrusion (104) at 30 to 65°, the end of the coating layer is prevented from being damaged, the coating layer is formed with a uniform thickness, and the nickel steel powder is prevented from being sprayed on parts other than the upper surface of the protrusion, thereby reducing the amount of nickel steel powder used and thus providing excellent economic efficiency. For example, the nickel steel powder can be sprayed by setting the normal direction reference spray nozzle (200) of the protrusion at an angle (θ) of 35 to 45°.

[0053] In one embodiment, the coating layer (120) may be formed with a thickness of 0.05 to 5 mm. Under the above conditions, the durability and adhesion of the coating layer may be excellent.

[0054] In one embodiment, the support stick can be joined via laser welding. Under these conditions, the support stick can be easily joined without damaging the coating layer and the mask frame.

[0056] Hereinafter, the structure and operation of the present invention will be explained in more detail through preferred embodiments. However, these are presented as preferred examples of the present invention and should not be interpreted in any way as limiting the present invention. Details not described herein can be sufficiently technically inferred by those skilled in the art, so such descriptions will be omitted.

[0058] Examples and Comparative Examples

[0059] Example 1

[0060] For the deposition of organic material on an OLED display panel, a mask assembly (2000) was prepared comprising a mask frame (100) having a hollow portion (101) formed on the inner side and a plurality of support sticks (110) bonded to the upper surface of the mask frame (100) to form a predetermined pattern. The mask frame (100) comprises a base portion (102); and a protrusion (104) formed along the inner edge of the base portion (102); and a coating layer (120) is formed on the surface of the protrusion (104) to bond the support sticks (110). The mask assembly (2000) is formed at an angle with respect to the normal direction of the base portion (102) with respect to the cross-section of the mask frame (100). The mask frame (100) and the support sticks (110) each comprise a nickel steel alloy (Invar-36).

[0061] During the process of replacing the damaged support stick (110) multiple times while manufacturing the display panel, the mask frame (100) is damaged and its height decreases below a standard value, so the support stick (110) is removed from the mask frame (100).

[0062] Next, nickel steel powder was sprayed at low temperature onto the mask frame portion from which the support stick had been removed to form a coating layer with a thickness of 0.5 mm.

[0063] Specifically, nickel steel powder was produced by introducing Invar-36 powder into the spray nozzle (200) of the spraying device, using compressed gas at a temperature of 700 to 900°C and a pressure of 3 to 6 MPa, with a stand-off distance (SOD) of 10 to 40 mm between the spray nozzles, a gas flow rate of 1,500 to 2,000 SLM, and a raw material (nickel steel powder) feeding amount of 3 to 5 kg / hr. As shown in FIG. 5, when spraying at low temperature, the spray nozzle (200) was adjusted to an angle (θ) of 45° relative to the surface of the protrusion (104) to spray the nickel steel powder, and the mixture was dried at 75 to 85°C to form a coating layer (120) with a hardness of 240 Hv. Then, a support stick (110) was laser-welded onto the coating layer (120) to repair the mask assembly (2000) as shown in FIG. 3.

[0065] Example 2

[0066] Except for adjusting the above-mentioned spray nozzle to an angle (θ) of 65˚ to spray nickel steel powder, a mask assembly (2000) with a hardness of 240 Hv was repaired in the same manner as in Example 1.

[0068] The present invention has been described above with reference to embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the invention. Explanation of the symbols

[0070] 100: Mask Frame 101: Hollow Part 102: Base part 104: Protrusion part 110: Support Stick 120: Coating Layer 200: Spray nozzle 1000, 2000, 3000: Mask assembly or repaired mask assembly

Claims

Claim 1 A method for repairing a mask assembly for manufacturing a display panel, comprising a mask frame having a hollow portion formed on the inner side and a plurality of support sticks bonded to the upper surface of the mask frame to form a predetermined pattern; wherein, when the height of the mask frame is reduced below a reference value due to damage to the mask frame, the method comprises the steps of: removing the support sticks from the mask frame; forming a coating layer by low-temperature spraying nickel steel powder onto the portion of the mask frame from which the support sticks have been removed; and bonding the support sticks onto the coating layer; wherein the low-temperature spraying involves introducing the nickel steel powder into a spray nozzle and using compressed gas with a temperature of 700 to 1100°C and a pressure of 1.5 to 7.5 MPa into the spray nozzle to accelerate the nickel steel powder into a supersonic jet of 300 to 1500 m / s and spray it onto the mask frame. Claim 2 delete Claim 3 A method for repairing a mask assembly according to claim 1, wherein the mask frame and the support stick each comprise a nickel steel alloy. Claim 4 A method for repairing a mask assembly according to claim 1, wherein the coating layer is formed by drying the nickel steel powder at 60 to 100°C after low-temperature spraying. Claim 5 A method for repairing a mask assembly according to claim 1, wherein the mask frame comprises a base portion; and a protrusion formed along the inner edge of the base portion; and a coating layer is formed on the surface of the protrusion so that the support stick is bonded thereto. Claim 6 A method for repairing a mask assembly according to claim 5, wherein the protrusion is formed at an angle with respect to the normal direction of the base portion with respect to the cross-section of the mask frame. Claim 7 A method for repairing a mask assembly according to claim 5, wherein the nickel steel powder is sprayed at an angle of 30 to 65˚ relative to the surface of the protrusion when forming the coating layer. Claim 8 A method for repairing a mask assembly according to claim 1, wherein the coating layer is formed with a thickness of 0.05 to 5 mm. Claim 9 A method for repairing a mask assembly according to claim 1, wherein the support stick is joined through laser welding.

Images