Method for manufacturing cover window and method for manufacturing display apparatus including cover window

Abstract

The present invention discloses a method for manufacturing a cover window with improved strength and a method for manufacturing a display device including such a cover window. The method for manufacturing a cover window according to the present invention comprises the steps of cutting a base glass into a separation glass, chamfering the separation glass, etching the front surface of the separation glass with a first etching solution containing a fluorine-based compound, etching the front surface of the separation glass with a second etching solution different from the first etching solution, and cleaning the separation glass with a basic cleaning solution.

Description

Technology Field

[0001] Embodiments of the present invention relate to a method for manufacturing a cover window and a method for manufacturing a display device including a cover window, and more specifically, to a method for manufacturing a cover window with improved strength and a method for manufacturing a display device including such a cover window. Background Technology

[0002] The cover window protects the display elements within the display device from external shocks, and the user provides input to the display device through the cover window. In the case of flexible displays, lightweight and thin cover windows are required, but there is a problem in that the strength of the cover window decreases as the cover window becomes lighter and thinner. To solve this problem, micro-defects present on the surface of the cover window are removed by etching the surface of the cover window with a solution containing a fluorine-based compound. The problem to be solved

[0003] However, in the conventional method of manufacturing a cover window and the method of manufacturing a display device including a cover window, there was a problem that when the surface of the cover window is etched with a solution containing a fluorine-based compound, insoluble fluoride is formed on the surface of the glass, and the glass surface beneath this insoluble fluoride is not etched.

[0004] The present invention aims to solve various problems, including those described above, by providing a method for manufacturing a cover window with improved strength and a method for manufacturing a display device including such a cover window. However, these problems are exemplary and do not limit the scope of the present invention. means of solving the problem

[0005] According to one aspect of the present invention, a method for manufacturing a cover window is provided, comprising the steps of: cutting a plate glass into a plate glass; chamfering the plate glass; etching the front surface of the plate glass with a first etching solution containing a fluorine-based compound; etching the front surface of the plate glass with a second etching solution different from the first etching solution; and cleaning the plate glass with a basic cleaning solution.

[0006] The first etching solution is an acidic solution, and the second etching solution may be a basic solution.

[0007] The first etching solution may include at least one of hydrofluoric acid (HF), ammonium fluoride (NH4F), and ammonium bifluoride (NH4HF2).

[0008] The above second etching solution may have a pH of 12 or higher.

[0009] The second etching solution may include at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

[0010] The step of etching with the second etching solution can be performed after the step of etching with the first etching solution.

[0011] The step of etching with the first etching solution is a step of etching the entire surface of the separation glass by immersing the separation glass in the first etching solution, and the step of etching with the second etching solution may be a step of etching the entire surface of the separation glass by immersing the separation glass in the second etching solution.

[0012] The ratio of the reduced thickness of the separation glass in the step of etching with the first etching solution to the reduced thickness of the separation glass in the step of etching with the second etching solution may be 4:1 to 9:1.

[0013] The method for manufacturing the above cover window further includes the step of cleaning the separation glass with an acidic cleaning solution, and the step of cleaning with the acidic cleaning solution may be performed between the step of etching with the second etching solution and the step of cleaning with the basic cleaning solution.

[0014] The above acidic cleaning solution has a pH of 2 or less and may not contain fluorine.

[0015] The above basic cleaning solution has a pH of 12 or higher and may contain at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

[0016] The second etching solution has a pH of 12 or higher and contains at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH), and the temperature of the basic cleaning solution in the step of cleaning with the basic cleaning solution may be lower than the temperature of the second etching solution in the step of etching with the second etching solution.

[0017] According to one aspect of the present invention, a method for manufacturing a display device is provided, comprising the steps of forming a thin-film transistor on a substrate, forming a display element electrically connected to the thin-film transistor on the upper portion of the thin-film transistor, manufacturing a cover window, and placing the cover window on the upper portion of the display element, wherein the step of manufacturing the cover window comprises the steps of cutting a base glass into a separation glass, chamfering the separation glass, etching the front surface of the separation glass with a first etching solution containing a fluorine-based compound, etching the front surface of the separation glass with a second etching solution different from the first etching solution, and cleaning the separation glass with a basic cleaning solution.

[0018] The first etching solution is an acidic solution, and the second etching solution may be a basic solution.

[0019] The first etching solution may include at least one of hydrofluoric acid (HF), ammonium fluoride (NH4F), and ammonium bifluoride (NH4HF2).

[0020] The above second etching solution may have a pH of 12 or higher.

[0021] The second etching solution may include at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

[0022] The step of etching with the second etching solution can be performed after the step of etching with the first etching solution.

[0023] The step of etching with the first etching solution is a step of etching the entire surface of the separation glass by immersing the separation glass in the first etching solution, and the step of etching with the second etching solution may be a step of etching the entire surface of the separation glass by immersing the separation glass in the second etching solution.

[0024] The ratio of the reduced thickness of the separation glass in the step of etching with the first etching solution to the reduced thickness of the separation glass in the step of etching with the second etching solution may be 4:1 to 9:1.

[0025] The method for manufacturing the above-described display device further includes the step of cleaning the separation glass with an acidic cleaning solution, and the step of cleaning with the acidic cleaning solution may be performed between the step of etching with the second etching solution and the step of cleaning with the basic cleaning solution.

[0026] The above acidic cleaning solution has a pH of 2 or less and may not contain fluorine.

[0027] The above basic cleaning solution has a pH of 12 or higher and may contain at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

[0028] The second etching solution has a pH of 12 or higher and contains at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH), and the temperature of the basic cleaning solution in the step of cleaning with the basic cleaning solution may be lower than the temperature of the second etching solution in the step of etching with the second etching solution.

[0029] Other aspects, features, and advantages other than those described above will become clear from the following specific details, claims, and drawings for implementing the invention. Effects of the invention

[0030] According to one embodiment of the present invention as described above, a method for manufacturing a cover window with improved strength and a method for manufacturing a display device including such a cover window can be provided. Of course, the scope of the present invention is not limited by these effects. Brief explanation of the drawing

[0031] FIG. 1 is a flowchart for explaining a method for manufacturing a cover window according to one embodiment of the present invention. FIG. 2 is a graph illustrating the strength of cover windows manufactured by a manufacturing method according to one embodiment of the present invention. Figure 3 is a micrograph of the surface of a cover window manufactured by the manufacturing method according to a comparative example. FIGS. 4 and FIGS. 5 are microscopic images of the surfaces of cover windows manufactured by a manufacturing method according to one embodiment of the present invention. FIG. 6 is a flowchart for explaining a method for manufacturing a cover window according to one embodiment of the present invention. FIG. 7 is a graph illustrating the strength of cover windows manufactured by a manufacturing method according to one embodiment of the present invention. FIGS. 8 and 9 are microscopic images of the surfaces of cover windows manufactured by a manufacturing method according to one embodiment of the present invention. FIG. 10 is a flowchart for explaining a method for manufacturing a display device according to one embodiment of the present invention. FIG. 11 is a cross-sectional view schematically illustrating a part of a display device manufactured by a manufacturing method according to one embodiment of the present invention. Specific details for implementing the invention

[0032] The present invention is capable of various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various forms.

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0034] In the following embodiments, when various components such as layers, films, regions, and plates are described as being "on" another component, this includes not only cases where they are "directly on" another component, but also cases where other components are interposed between them. Furthermore, for convenience of explanation, the size of components in the drawings may be exaggerated or reduced. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, so the present invention is not necessarily limited to what is illustrated.

[0035] In the following embodiments, the x-axis, y-axis, and z-axis are not limited to three axes in an orthogonal coordinate system and can be interpreted in a broader sense that includes them. For example, the x-axis, y-axis, and z-axis may be orthogonal to each other, but they may also refer to different directions that are not orthogonal to each other.

[0036] In the following examples, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0037] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0038] In the following embodiments, terms such as "comprising" or "having" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0039] In this specification, "A and / or B" indicates the case where it is A, B, or both A and B. And, "at least one of A and B" indicates the case where it is A, B, or both A and B.

[0040] FIG. 1 is a flowchart for explaining a method for manufacturing a cover window according to an embodiment of the present invention. As shown in FIG. 1, a method for manufacturing a cover window according to an embodiment of the present invention may include the steps of cutting a base glass into a separated glass (S10), chamfering the separated glass (S20), etching the separated glass with a first etching solution (S30), etching the separated glass with a second etching solution (S40), and cleaning the separated glass with a basic cleaning solution (S50).

[0041] In the step (S10) of cutting the original glass into separated glass, the original glass can be cut into a stacked form of multiple separated glass by stacking multiple original glass and then cutting the stacked original glass into a preset size all at once. For example, the stacked original glass can be cut simultaneously using a wheel, laser, water jet, or etching to obtain groups of stacked separated glass.

[0042] The original glass may be ultra-thin glass (UTG). Specifically, the original glass may have a thickness of 30 µm to 50 µm. As the thickness of the glass decreases, it may have flexible properties, but the strength of the glass may decrease along with this. Therefore, if the thickness of the original glass is less than 30 µm, the strength of the original glass may decrease excessively. On the other hand, if the thickness exceeds 50 µm, the original glass may not have flexible properties or the flexible properties may not be sufficient. Meanwhile, the original glass may include soda-lime glass, alkali aluminosilicate glass, borosilicate glass, or lithium alumina-silicate glass.

[0043] In the step (S20) of chamfering the separated glass, the edges of the sides of the stacked multiple separated glass plates can be chamfered simultaneously. The chamfering of the separated glass plates can be performed through a Computerized Numerical Control (CNC) process.

[0044] In the step (S30) of etching the separation glass with the first etching solution, the entire surface of the separation glass can be etched with the first etching solution containing a fluorine-based compound. Specifically, the entire surface of the separation glass can be etched by immersing the separation glass in the first etching solution. That is, the first etching bath can be filled with the first etching solution, and the separation glass can be immersed in the first etching bath for about 1 to 2 minutes. After that, the separation glass can be removed from the first etching bath.

[0045] The first etching solution may be an acidic solution. An acidic solution refers to a solution with a hydrogen ion concentration index (hereinafter pH) of less than 7. In contrast, a basic solution refers to a solution with a pH greater than 7. The first etching solution may contain a fluorine-based compound. The fluorine-based compound can chemically react with at least some of the materials constituting the glass to dissolve the glass. Accordingly, by etching the entire surface of the separation glass with the first etching solution containing the fluorine-based compound, the surface of the separation glass can be uniformly dissolved to remove fine defects present on the surface.

[0046] The fluorine-based compound contained in the first etching solution may be a compound in which fluoride ions or polyatomic fluoride ions dissociate. For example, the fluorine compound may be hydrofluoric acid (HF), ammonium fluoride (NH4F), sodium fluoride (NaF), potassium fluoride (KF), ammonium bifluoride (NH4HF2, It may include at least one of ammonium bifluoride, sodium bifluoride (NaHF2), and potassium bifluoride (KHF2), but the present invention is not limited thereto. Meanwhile, the fluorine-based compound is the main component of the first etching solution, and the first etching solution may further include an inorganic acid or an organic acid.

[0047] Fluorine-based compounds can improve the etching rate of separation glass. Specifically, fluorine-based compounds dissolve the surface of separation glass in a short time, and accordingly, fine defects present on the surface of the glass can be removed with the first etching solution in a short time. However, fluorine-based compounds may chemically react with metal ions present on the surface of separation glass to form insoluble fluoride. Since this insoluble fluoride is located on the surface of separation glass, the portion of separation glass located beneath the insoluble fluoride may not be etched by the first etching solution. As a result, the roughness of the separation glass surface increases, and fine defects on the surface of separation glass may not be completely removed.

[0048] In the step (S40) of etching the separation glass with the second etching solution, the entire surface of the separation glass can be etched with the second etching solution, which is different from the first etching solution. Specifically, the entire surface of the separation glass can be etched by immersing the separation glass in the second etching solution. That is, a second etching bath, which is different from the first etching bath, can be filled with the second etching solution, and the temperature of the second etching bath can be maintained at 70°C to 90°C. After immersing the separation glass in this second etching bath for about 30 minutes, the separation glass can be removed from the second etching bath.

[0049] The second etching solution may be a basic solution. Specifically, the pH of the second etching solution may be 12 or higher. The basic solution may chemically react with at least some of the materials constituting the glass to dissolve the glass. Accordingly, even if insoluble fluoride generated by the chemical reaction between the first etching solution and the metal ions of the glass is present on the glass surface, such insoluble fluoride can be effectively removed. The second etching solution may include at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH), but the present invention is not limited thereto.

[0050] Meanwhile, the temperature of the second etching solution may be maintained at 70°C to 90°C. If the temperature of the second etching solution is below 70°C, the etching speed of the second etching solution may be excessively slow, so the separation glass may not be sufficiently etched within a specific time. However, in the method for manufacturing a cover window according to the present embodiment, the temperature of the second etching solution is 70°C to 90°C, and accordingly, the separation glass can be sufficiently etched within a short time even by a basic solution.

[0051] The second etching solution may not contain fluorine-based compounds. Accordingly, the second etching solution may not form insoluble fluorides. Additionally, the second etching solution may chemically react with at least some of the materials constituting the glass to dissolve the glass. Along with this, insoluble fluorides generated by the chemical reaction between fluorine-based compounds and metal ions can also be effectively removed. As a result, the roughness of the separation glass surface is reduced, and fine defects on the separation glass surface can be completely removed or the removal of fine defects can be maximized. A detailed explanation of the effects resulting from etching the separation glass with the second etching solution will be provided later.

[0052] Meanwhile, the second etching solution, which is a basic solution, can dissolve the surface of the separation glass, but its etching speed may be slower compared to the first etching solution containing a fluorine-based compound. Therefore, by etching the separation glass more using the first etching solution, which has a faster etching speed, and then etching the separation glass with the second etching solution, insoluble fluoride generated by the chemical reaction between the first etching solution and the metal ions of the glass can be effectively removed. Through this, the total time required for etching the separation glass can be reduced.

[0053] The thickness of the separation glass reduced by etching with the first etching solution and the thickness of the separation glass reduced by etching with the second etching solution may differ. That is, the ratio of the thickness of the separation glass reduced by etching with the first etching solution to the thickness of the separation glass reduced by etching with the second etching solution may be 4:1 to 9:1. If the ratio of the thickness of the separation glass reduced by etching with the first etching solution to the thickness of the separation glass reduced by etching with the second etching solution is less than 4:1, the time required to etch the separation glass with the first etching solution is reduced compared to when the ratio is 4:1 or more, so the total time required to etch the separation glass to reduce the thickness of the separation glass by a preset thickness may increase. When the ratio of the thickness of the separated glass reduced by etching with the first etching solution to the thickness of the separated glass reduced by etching with the second etching solution exceeds 9:1, the time required to etch the separated glass with the second etching solution is reduced compared to when the ratio is 9:1 or less, so insoluble fluoride generated by the chemical reaction between the first etching solution and the metal ions of the glass may not be sufficiently removed.

[0054] In the step (S50) of cleaning the separation glass with a basic cleaning solution, the entire surface of the separation glass can be cleaned with the basic cleaning solution. Specifically, the entire surface of the separation glass can be cleaned by immersing the separation glass in the basic cleaning solution. That is, a basic cleaning bath can be filled with the basic cleaning solution, and the separation glass can be immersed in the basic cleaning solution for about 5 minutes. After that, the separation glass can be removed from the basic cleaning bath.

[0055] The basic cleaning solution may be a basic solution. Specifically, the basic cleaning solution may have a pH of 12 or higher. For example, the basic cleaning solution may include at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH). However, the present invention is not limited thereto, and any basic solution having a pH of 12 or higher may be used as a basic cleaning solution.

[0056] When cleaning the separation glass with a basic cleaning solution, the temperature of the basic cleaning solution may be lower than the temperature of the second etching solution when etching the separation glass with a second etching solution. Specifically, when etching the separation glass with the second etching solution, the temperature of the second etching solution may be 70°C to 90°C, and when cleaning the separation glass with a basic cleaning solution, the temperature of the basic cleaning solution may be 40°C or lower. As described above, since the temperature of the basic cleaning solution is less than 70°C, the surface of the separation glass may hardly melt due to the basic cleaning solution. However, by cleaning the separation glass with a basic cleaning solution, foreign substances present on the surface of the separation glass can be removed.

[0057] FIG. 2 is a graph illustrating the strength of cover windows manufactured by a manufacturing method according to an embodiment of the present invention. For convenience of explanation, FIG. 2 illustrates the results of strength evaluations for a first cover window (C1) manufactured by a manufacturing method according to a comparative example, and for a second cover window (C2) and a third cover window (C3) manufactured by a manufacturing method according to an embodiment of the present invention. Specifically, FIG. 2 illustrates the results of a drop test to evaluate impact resistance. The drop test was performed by dropping the same ballpoint pen vertically from the first cover window (C1), the second cover window (C2), and the third cover window (C3), and measuring the height at which the first cover window (C1), the second cover window (C2), and the third cover window (C3) are damaged by the ballpoint pen.

[0058] The first cover window (C1) may be a cover window that has not undergone the step (S40) of etching with the second etching solution among the steps of the manufacturing method according to one embodiment of the present invention. The second cover window (C2) and the third cover window (C3) may be cover windows that have undergone the step (S40) of etching with the second etching solution, as manufactured by the manufacturing method according to one embodiment of the present invention. Specifically, the second cover window (C2) may have a ratio of the thickness of the separation glass reduced by etching with the first etching solution to the thickness of the separation glass reduced by etching with the second etching solution of 9:1. The third cover window (C3) may have a ratio of the thickness of the separation glass reduced by etching with the first etching solution to the thickness of the separation glass reduced by etching with the second etching solution of 4:1. That is, the separation glass of the third cover window (C3) can be etched more with the second etching solution than the separation glass of the second cover window (C2).

[0059] As illustrated in FIG. 2, the first cover window (C1) has a result value distributed in the range of 1.0 cm to 2.0 cm and can have impact resistance against a ballpoint pen dropped from an average height of 1.3 cm. The second cover window (C2) also has a result value distributed in the range of 1.0 cm to 2.0 cm, but can have impact resistance against a ballpoint pen dropped from an average height of 1.4 cm. Meanwhile, the third cover window (C3) has a result value distributed in the range of 1.5 cm to 2.0 cm and can have impact resistance against a ballpoint pen dropped from an average height of 1.8 cm. That is, the second cover window (C2) and the third cover window (C3) manufactured by the manufacturing method according to one embodiment of the present invention can have improved impact resistance compared to the first cover window (C1) manufactured by the manufacturing method according to the comparative example. That is, by further including the step (S40) of etching with a second etching solution in the method of manufacturing a cover window, a cover window with improved strength can be manufactured.

[0060] The strength of the cover window surface may be related to the roughness of the cover window. Specifically, the greater the roughness of the cover window surface, the easier it is for cracks to propagate due to external impact, so the strength of the cover window may be low. FIG. 3 is a micrograph of the surface of a cover window manufactured by a manufacturing method according to a comparative example, and FIG. 4 and FIG. 5 are micrographs of the surfaces of cover windows manufactured by a manufacturing method according to an embodiment of the present invention. Specifically, FIG. 3 is a micrograph of the surface of a first cover window (C1), FIG. 4 is a micrograph of the surface of a second cover window (C2), and FIG. 5 is a micrograph of the surface of a third cover window (C3).

[0061] As illustrated in FIGS. 3 and 4, the roughness of the surface of the second cover window (C2) may be smaller than the roughness of the surface of the first cover window (C1). This may be because the insoluble fluoride on the surface of the second cover window (C2) is removed and fine defects are reduced by the step (S40) of etching with the second etching solution. Additionally, as illustrated in FIG. 5, the roughness of the surface of the third cover window (C3) may be smaller than the roughness of the surface of the second cover window (C2). This may be because, as previously mentioned, the separation glass of the third cover window (C3) is etched more with the second etching solution than the separation glass of the second cover window (C2), thereby removing more of the insoluble fluoride on the surface of the third cover window (C3) than the insoluble fluoride on the surface of the second cover window (C2), and further reducing fine defects.

[0062] Accordingly, as shown in FIG. 2, the first cover window (C1) with high roughness has low strength, and the third cover window (C3) with low roughness can have high strength.

[0063] As illustrated in FIG. 6, which is a flowchart for explaining a method for manufacturing a cover window according to one embodiment of the present invention, the method for manufacturing a cover window according to one embodiment of the present invention may further include a step (S45) of cleaning the separation glass with an acidic cleaning solution between the step (S40) of etching the separation glass with a second etching solution and the step (S50) of cleaning the separation glass with a basic cleaning solution.

[0064] In the step (S45) of cleaning the separation glass with an acidic cleaning solution, the entire surface of the separation glass can be cleaned with the acidic cleaning solution. Specifically, the entire surface of the separation glass can be cleaned by immersing the separation glass in the acidic cleaning solution. That is, an acidic cleaning bath can be filled with the acidic cleaning solution, and the separation glass can be immersed in the acidic cleaning solution for about 1 to 10 minutes. After that, the separation glass can be removed from the acidic cleaning bath.

[0065] The acidic cleaning solution may be an acidic solution. Specifically, the acidic cleaning solution may have a pH of 2 or less. For example, the acidic cleaning solution may be nitric acid (HNO3) or sulfuric acid (H2 S It may include at least one of O4), and hydrochloric acid (HCl). However, the present invention is not limited thereto, and an acidic solution having a pH of 2 or less may be used as an acidic cleaning solution. When cleaning a separation plate glass with an acidic cleaning solution, the temperature of the acidic cleaning solution may be 40°C or lower.

[0066] The acidic cleaning solution may not contain fluorine-based compounds. Accordingly, the acidic cleaning solution may not form insoluble fluorides. The acidic cleaning solution removes some of the metal ions on the surface of the separation glass, and as a result, the areas where the metal ions were removed may exist as empty spaces. Therefore, even if an external impact is applied to the cover window, the impact can be mitigated by these empty spaces. In other words, the strength of the cover window can be improved.

[0067] In addition, the acidic cleaning solution can chemically react with at least some of the materials constituting the glass to dissolve the glass. Through this, insoluble fluorides formed by the chemical reaction between fluorine-based compounds and metal ions, which are not removed by etching using the second etching solution, can also be additionally removed. Accordingly, the roughness of the separation glass surface is reduced compared to when it is not cleaned with the acidic cleaning solution, and more fine defects on the separation glass surface can be removed compared to when it is not cleaned with the acidic cleaning solution.

[0068] FIG. 7 is a graph illustrating the strength of cover windows manufactured by a manufacturing method according to an embodiment of the present invention. For convenience of explanation, FIG. 7 illustrates the results of strength evaluations for a first cover window (C1) manufactured by a manufacturing method according to a comparative example, and for a fourth cover window (C4), a fifth cover window (C5), a sixth cover window (C6), and a seventh cover window (C7) manufactured by a manufacturing method according to an embodiment of the present invention. Specifically, FIG. 7 illustrates the results of a drop test to evaluate impact resistance. The drop test was performed by dropping the same ballpoint pen vertically from the first cover window (C1), the fourth cover window (C4), the fifth cover window (C5), the sixth cover window (C6), and the seventh cover window (C7), and measuring the height at which the first cover window (C1), the fourth cover window (C4), the fifth cover window (C5), the sixth cover window (C6), and the seventh cover window (C7) are damaged by the ballpoint pen.

[0069] The first cover window (C1) may be a cover window that has not undergone the step of etching with a second etching solution (S40) and the step of cleaning with an acidic cleaning solution (S45) among the steps of the manufacturing method according to one embodiment of the present invention. The fourth cover window (C4), the fifth cover window (C5), the sixth cover window (C6), and the seventh cover window (C7) may be cover windows that have undergone the step of cleaning with an acidic cleaning solution (S45) without undergoing the step of etching with a second etching solution (S40). Specifically, the fourth cover window (C4) may be a cover window that has been cleaned for 1 minute with an acidic cleaning solution containing nitric acid, and the fifth cover window (C5) may be a cover window that has been cleaned for 3 minutes with an acidic cleaning solution containing nitric acid. The 6th cover window (C6) may be a cover window cleaned for 5 minutes with an acidic cleaning solution containing nitric acid, and the 7th cover window (C7) may be a cover window cleaned for 10 minutes with an acidic cleaning solution containing nitric acid.

[0070] As illustrated in FIG. 7, the first cover window (C1) has a result value distributed in the range of 1.0 cm to 2.0 cm and can be impact resistant to a ballpoint pen dropped from an average height of 1.3 cm. The fourth cover window and the fifth cover window (C5) also have result values ​​distributed in the range of 1.0 cm to 2.0 cm, but can be impact resistant to a ballpoint pen dropped from an average height of 1.7 cm. Meanwhile, the sixth cover window (C6) and the seventh cover window (C7) can be impact resistant to a ballpoint pen dropped from a height of 2.0 cm, and the deviation of the result value is small. That is, the fourth cover window (C4), the fifth cover window (C5), the sixth cover window (C6), and the seventh cover window (C7) manufactured by the manufacturing method according to one embodiment of the present invention may have improved impact resistance compared to the first cover window (C1) manufactured by the manufacturing method according to the comparative example. That is, by further including a step (S45) of cleaning with an acidic cleaning solution in the manufacturing method of the cover window, a cover window with improved strength can be manufactured.

[0071] As described above, the strength of the cover window surface may be related to the roughness of the cover window. FIGS. 8 and 9 are micrographs of the surfaces of cover windows manufactured by a manufacturing method according to an embodiment of the present invention. Specifically, FIG. 8 is a micrograph of the surface of the fifth cover window (C5), and FIG. 9 is a micrograph of the surface of the seventh cover window (C7).

[0072] As illustrated in FIG. 8, the roughness of the surface of the fifth cover window (C5) may be smaller than the roughness of the surface of the first cover window (C1). This may be because the insoluble fluoride on the surface of the fifth cover window (C5) is removed and fine defects are reduced by the step (S45) of cleaning with an acidic cleaning solution. Additionally, as illustrated in FIG. 9, the roughness of the surface of the seventh cover window (C7) may be smaller than the roughness of the surface of the fifth cover window (C5). This may be because, as previously mentioned, the separation glass of the seventh cover window (C7) is cleaned more with the acidic cleaning solution than the separation glass of the fifth cover window (C5), thereby removing more of the insoluble fluoride on the surface of the seventh cover window (C7) than the insoluble fluoride on the surface of the fifth cover window (C5), and further reducing fine defects.

[0073] Accordingly, as shown in FIG. 7, the first cover window (C1) with high roughness has low strength, and the seventh cover window (C7) with low roughness can have high strength.

[0074] Up to this point, a method for manufacturing a cover window has been described, but the present invention is not limited thereto. A method for manufacturing a display device including such a cover window is also considered to fall within the scope of the present invention. Below, a method for manufacturing a display device including such a cover window will be described.

[0075] FIG. 10 is a flowchart for explaining a method for manufacturing a display device according to an embodiment of the present invention. FIG. 11 is a cross-sectional view schematically illustrating a part of a display device (1) manufactured by a method according to an embodiment of the present invention. Specifically, the display device (1) manufactured according to an embodiment of the present invention may include a cover window (300).

[0076] As illustrated in FIG. 10, a method for manufacturing a display device according to one embodiment of the present invention may include the steps of forming a thin-film transistor (S1100), forming a display element (S1200), manufacturing a cover window (S1300), and placing the cover window (S1400).

[0077] In the step (S1100) of forming a thin film transistor, a thin film transistor (TFT) can be formed on a substrate (100). The substrate (100) may include various materials having flexible or bendable properties. For example, the substrate (100) may include glass, metal, or polymer resin. Additionally, the substrate (100) may include polymer resins such as polyethersulfone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, or cellulose acetate propionate. Of course, the substrate (100) may have a multilayer structure including two layers each containing such a polymer resin and a barrier layer containing an inorganic material (such as silicon oxide, silicon nitride, silicon oxynitride) interposed between the layers, and various other variations are possible.

[0078] As illustrated in FIG. 11, a thin-film transistor (TFT) comprises a semiconductor layer (Act) comprising amorphous silicon, polycrystalline silicon, an oxide semiconductor material, or an organic semiconductor material, a gate electrode (GE), a source electrode (SE), and a drain electrode (DE). To ensure insulation between the semiconductor layer (Act) and the gate electrode (GE), a gate insulating layer (120) comprising an inorganic material such as silicon oxide, silicon nitride, and / or silicon oxynitride may be interposed between the semiconductor layer (Act) and the gate electrode (GE). Additionally, a first interlayer insulating layer (140) comprising an inorganic material such as silicon oxide, silicon nitride, and / or silicon oxynitride may be disposed on the upper surface of the gate electrode (GE), and a second interlayer insulating layer (160) may be disposed to cover the source electrode (SE) and the drain electrode (DE). In this way, insulating layers comprising inorganic materials may be formed through CVD or ALD. And a planarization layer (170) may be disposed on the thin-film transistor (TFT). The planarization layer (170) may serve to generally planarize the upper surface of the thin-film transistor (TFT). This planarization layer (170) may include organic materials such as, for example, acrylic, BCB (Benzocyclobutene), or HMDSO (hexamethyldisiloxane). In FIG. 11, the planarization layer (170) is shown as a single layer, but various variations are possible, such as being multilayer.

[0079] In the step (S1200) of forming a display element, a display element (280) electrically connected to the thin-film transistor (TFT) can be formed on top of the thin-film transistor (TFT). The display element (280) may be, for example, an organic light-emitting element having a pixel electrode (281), a counter electrode (283), and an intermediate layer (282) interposed between them and including a light-emitting layer. The fact that the display element (280) is electrically connected to the thin-film transistor (TFT) can be understood as the pixel electrode (281) of the organic light-emitting element being electrically connected to the thin-film transistor (TFT).

[0080] As shown in FIG. 11, the pixel electrode (281) is electrically connected to a thin-film transistor (TFT) by contacting either the source electrode (SE) or the drain electrode (DE) through an opening formed in the planarization layer (170), etc. The pixel electrode (281) includes a transparent conductive layer formed of a transparent conductive oxide such as ITO, In2O3, or IZO, and a reflective layer formed of a metal such as Al or Ag. For example, the pixel electrode (281) may have a three-layer structure of ITO / Ag / ITO.

[0081] A pixel defining film (190) may be disposed on the upper portion of the flattening layer (170). This pixel defining film (190) serves to define pixels by having openings corresponding to each pixel, that is, openings that expose at least the central portion of the pixel electrode (281). Additionally, as shown in FIG. 11, the pixel defining film (190) serves to prevent arcs from occurring at the edge of the pixel electrode (281) by increasing the distance between the edge of the pixel electrode (281) and the opposing electrode (283) above the pixel electrode (281). Such a pixel defining film (190) may include, for example, an organic material such as polyimide or HMDSO (hexamethyldisiloxane).

[0082] The intermediate layer (282) of the organic light-emitting diode may include a low-molecular-weight or high-molecular-weight material. If the intermediate layer (282) includes a low-molecular-weight material, the intermediate layer (282) may have a structure in which a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL) are stacked in a single or composite structure, and may be formed by a vacuum deposition method. If the intermediate layer (282) includes a high-molecular-weight material, the intermediate layer (282) may have a structure including a hole transport layer (HTL) and an emission layer (EML). In this case, the hole transport layer may include PEDOT, and the emission layer may include a high-molecular-weight material such as a PPV (polyphenylene vinylene) system and a polyfluorene system. This intermediate layer (282) can be formed by screen printing, inkjet printing, laser thermal imaging (LITI), etc. Of course, the intermediate layer (282) is not necessarily limited to this and can have various structures. Also, the intermediate layer (282) may include a layer that is integral across a plurality of pixel electrodes (281), or may include a layer patterned to correspond to each of the plurality of pixel electrodes (281).

[0083] The counter electrode (283) may be integrally formed in a plurality of organic light-emitting diodes and may correspond to a plurality of pixel electrodes (281). This counter electrode (283) may include a light-transmitting conductive layer formed of ITO, In2O3, or IZO, and may also include a semi-transparent film containing a metal such as Al or Ag. For example, the counter electrode (283) may be a semi-transparent film containing Mg or Ag.

[0084] Since these organic light-emitting devices can be easily damaged by moisture or oxygen from the outside, an encapsulation layer (290) can cover and protect these organic light-emitting devices. The encapsulation layer (290) may include a first inorganic encapsulation layer (291), an organic encapsulation layer (292), and a second inorganic encapsulation layer (293), as shown in FIG. 11.

[0085] The first inorganic sealing layer (291) covers the counter electrode (283) and may include silicon oxide, silicon nitride and / or silicon oxynitride, etc. Of course, other layers such as a capping layer may be interposed between the first inorganic sealing layer (291) and the counter electrode (283) as needed. Since this first inorganic sealing layer (291) is formed along the structure below it, its upper surface is not flat as shown in FIG. 11. The organic sealing layer (292) covers this first inorganic sealing layer (291), and unlike the first inorganic sealing layer (291), its upper surface can be made approximately flat. These organic encapsulation layers (292) may include one or more materials selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, polyarylate, and hexamethyldisiloxane. The second inorganic encapsulation layer (293) covers the organic encapsulation layer (292) and may include silicon oxide, silicon nitride and / or silicon oxynitride, etc.

[0086] In this way, the bag layer (290) includes a first inorganic bag layer (291), an organic bag layer (292), and a second inorganic bag layer (293). Through this multilayer structure, even if a crack occurs within the bag layer (290), such cracks can be prevented from connecting between the first inorganic bag layer (291) and the organic bag layer (292), or between the organic bag layer (292) and the second inorganic bag layer (293). This prevents or minimizes the formation of a path for moisture or oxygen from the outside to penetrate into the display device (1).

[0087] The step of manufacturing a cover window (S1300) may include the step of cutting the original glass into a separated glass, the step of chamfering the separated glass, the step of etching the separated glass with a first etching solution, the step of etching the separated glass with a second etching solution, the step of cleaning the separated glass with an acidic cleaning solution, and the step of cleaning the separated glass with a basic cleaning solution.

[0088] The above description regarding the steps of cutting the plate glass into a plate glass (S10), chamfering the plate glass (S20), etching the plate glass with a first etching solution (S30), etching the plate glass with a second etching solution (S40), cleaning the plate glass with an acidic cleaning solution (S45), and cleaning the plate glass with a basic cleaning solution (S50) can also be applied to the steps of cutting the original glass into a plate glass, chamfering the plate glass, etching the plate glass with a first etching solution, etching the plate glass with a second etching solution, cleaning the plate glass with an acidic cleaning solution, and cleaning the plate glass with a basic cleaning solution, which are included in the step of manufacturing a cover window according to the present embodiment (S1300). Therefore, redundant descriptions regarding this are omitted.

[0089] In the step of placing the cover window (S1400), the cover window (300) may be placed on the upper surface of the substrate (100). Specifically, the display device (1) may include a display panel and a cover window (300), and the display panel may include a thin-film transistor (TFT) and a display element (280). The cover window (300) is placed on the display panel, and the cover window (300) may be adhered to the display panel. For example, the cover window (300) may be adhered to the display panel by a pressure-sensitive adhesive (PSA). The cover window (300) may be placed on the upper surface of the display panel to protect the display panel from external impact.

[0090] As such, the present invention has been described with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims. Explanation of the symbols

[0091] 100: Substrate TFT: Thin-film transistor 280: Display element 300: Cover Window

Claims

Claim 1 A method for manufacturing a cover window, comprising: a step of cutting a plate glass into a plate glass; a step of chamfering the plate glass; a step of etching the entire surface of the plate glass with a first etching solution containing a fluorine-based compound; a step of etching the entire surface of the plate glass with a second etching solution different from the first etching solution; and a step of cleaning the plate glass with a basic cleaning solution; wherein the first etching solution is an acidic solution and the second etching solution is a basic solution. Claim 2 delete Claim 3 A method for manufacturing a cover window according to claim 1, wherein the first etching solution comprises at least one of hydrofluoric acid (HF), ammonium fluoride (NH4F), and ammonium bifluoride (NH4HF2). Claim 4 A method for manufacturing a cover window according to claim 1, wherein the second etching solution has a pH of 12 or higher. Claim 5 A method for manufacturing a cover window according to claim 4, wherein the second etching solution comprises at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Claim 6 A method for manufacturing a cover window according to claim 1, wherein the step of etching with the second etching solution is performed after the step of etching with the first etching solution. Claim 7 A method for manufacturing a cover window according to claim 1, wherein the step of etching with the first etching solution is a step of etching the front surface of the separation glass by immersing the separation glass in the first etching solution, and the step of etching with the second etching solution is a step of etching the front surface of the separation glass by immersing the separation glass in the second etching solution. Claim 8 A method for manufacturing a cover window according to claim 1, wherein the ratio of the reduced thickness of the separation glass in the step of etching with the first etching solution to the reduced thickness of the separation glass in the step of etching with the second etching solution is 4:1 to 9:

1. Claim 9 A method for manufacturing a cover window according to claim 1, further comprising the step of cleaning the separation glass with an acidic cleaning solution; wherein the step of cleaning with the acidic cleaning solution is performed between the step of etching with the second etching solution and the step of cleaning with the basic cleaning solution. Claim 10 A method for manufacturing a cover window according to claim 9, wherein the acidic cleaning solution has a pH of 2 or less and does not contain fluorine. Claim 11 A method for manufacturing a cover window according to claim 9, wherein the basic cleaning solution has a pH of 12 or higher and comprises at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Claim 12 A method for manufacturing a cover window according to claim 11, wherein the second etching solution has a pH of 12 or higher and comprises at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH), and the temperature of the basic cleaning solution in the step of cleaning with the basic cleaning solution is lower than the temperature of the second etching solution in the step of etching with the second etching solution. Claim 13 A method for manufacturing a display device, comprising: a step of forming a thin-film transistor on a substrate; a step of forming a display element electrically connected to the thin-film transistor on the upper portion of the thin-film transistor; a step of manufacturing a cover window; and a step of placing the cover window on the upper portion of the display element; wherein the step of manufacturing the cover window comprises: a step of cutting a base glass into a separation glass; a step of chamfering the separation glass; a step of etching the front surface of the separation glass with a first etching solution containing a fluorine-based compound; a step of etching the front surface of the separation glass with a second etching solution different from the first etching solution; and a step of cleaning the separation glass with a basic cleaning solution; wherein the first etching solution is an acidic solution and the second etching solution is a basic solution. Claim 14 delete Claim 15 A method for manufacturing a display device according to claim 13, wherein the first etching solution comprises at least one of hydrofluoric acid (HF), ammonium fluoride (NH4F), and ammonium bifluoride (NH4HF2). Claim 16 In claim 13, the method for manufacturing a display device wherein the second etching solution has a pH of 12 or higher. Claim 17 A method for manufacturing a display device according to claim 16, wherein the second etching solution comprises at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Claim 18 A method for manufacturing a display device according to claim 13, wherein the step of etching with the second etching solution is performed after the step of etching with the first etching solution. Claim 19 A method for manufacturing a display device according to claim 13, wherein the step of etching with the first etching solution is a step of etching the entire surface of the separation glass by immersing the separation glass in the first etching solution, and the step of etching with the second etching solution is a step of etching the entire surface of the separation glass by immersing the separation glass in the second etching solution. Claim 20 A method for manufacturing a display device according to claim 13, wherein the ratio of the reduced thickness of the separation glass in the step of etching with the first etching solution to the reduced thickness of the separation glass in the step of etching with the second etching solution is 4:1 to 9:

1. Claim 21 A method for manufacturing a display device according to claim 13, further comprising the step of cleaning the separation glass with an acidic cleaning solution; wherein the step of cleaning with the acidic cleaning solution is performed between the step of etching with the second etching solution and the step of cleaning with the basic cleaning solution. Claim 22 A method for manufacturing a display device according to claim 21, wherein the acidic cleaning solution has a pH of 2 or less and does not contain fluorine. Claim 23 A method for manufacturing a display device according to claim 21, wherein the basic cleaning solution has a pH of 12 or higher and comprises at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH). Claim 24 A method for manufacturing a display device according to claim 23, wherein the second etching solution has a pH of 12 or higher and comprises at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH), and the temperature of the basic cleaning solution in the step of cleaning with the basic cleaning solution is lower than the temperature of the second etching solution in the step of etching with the second etching solution.

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