Window manufacturing method

Abstract

To provide a manufacturing method of a window having improved compression stress characteristics and impact strength by optimizing a cleaning step.SOLUTION: A window manufacturing method of the present invention comprises a step of providing an initial window having a first compressive stress value, and a cleaning step for cleaning the initial window and providing a window with a second compressive stress value, in which the cleaning step has a pickling step of pickling the initial window, and an alkali cleaning step of alkali cleaning the pickled initial window, a linear relationship is proposed to a difference between the first compressive stress value and the second compressive stress value, the temperature and time of the pickling step, and a method to effectively controlling the mechanical properties of a window by controlling the process conditions of the pickling step is proposed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a window manufacturing method, and more particularly to a window manufacturing method including a cleaning step. [Background technology]

[0002] The electronic device includes a window, a housing, and electronic elements. The electronic device includes various elements that are activated by electrical signals, such as display elements, touch elements, or detection elements.

[0003] The window protects the electronic component and provides the user with an active area. Through this, the user can provide input to the electronic component or receive information generated by the electronic component via the window. Furthermore, the electronic component is reliably protected from external shocks through the window.

[0004] Recently, the trend towards slimmer electronic components has led to a demand for lighter and thinner windows. To compensate for the resulting structural weakness, research is being conducted on window manufacturing methods that possess excellent strength and surface durability. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Korean Published Patent Publication No. 10-2018-0055711 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above-mentioned prior art, and the object of the present invention is to provide a window manufacturing method in which the compressive stress characteristics and impact strength are improved by optimizing the cleaning step. [Means for solving the problem]

[0007] A window manufacturing method according to one aspect of the present invention, made to achieve the above objective, comprises the steps of: providing an initial window having a first compressive stress value; and cleaning the initial window to provide a window having a second compressive stress value, wherein the cleaning step includes an acid pickling step of acid pickling the initial window and an alkaline cleaning step of alkaline cleaning the acid pickled initial window, and the difference between the first compressive stress value and the second compressive stress value satisfies the following formulas 1 and 2. [Formula 1] ΔCS(MPa) = δ·t(min) + θ [Formula 2] ΔCS(MPa) = α·T(℃) + β In equation 1, 0 < δ ≤ 10 and -300 ≤ θ < 0; in equation 2, 0 < α ≤ 10 and 0 < β ≤ 50; in equations 1 and 2, ΔCS is the absolute value of the difference between the first compressive stress value and the second compressive stress value, T is the temperature of the pickling step, and t is the holding time of the pickling step.

[0008] The temperature T of the pickling step may be between 40°C and 70°C. The holding time t in the pickling step may be 1 minute (min) or more and 20 minutes (min) or less. The difference between the first compressive stress value and the second compressive stress value can satisfy the following equation 3. [Formula 3] ΔCS(MPa)=ν·T(℃)+ω·t(min)+γ In equation 3, 0 < ν ≤ 10, 0 < ω ≤ 20, -150 ≤ γ ≤ -50, and ΔCS, T, and t are as defined in equations 1 and 2. The difference between the first compressive stress value and the second compressive stress value can satisfy the following equation 3-1. [Formula 3-1] ΔCS(MPa) = 4T(℃) + 2t(min) + γ In equation 3-1, -150 ≤ γ ≤ -50, and ΔCS, T, and t are as defined in equations 1 and 2. The difference between the first compressive stress value and the second compressive stress value is proportional to the amount of cleaning in the cleaning step, and the amount of cleaning can be the amount removed per unit area of the initial window removed from the surface of the initial window. The amount of cleaning may satisfy the following formulas 4 and 5. [Formula 4] L AB (mg / cm 2 ) = δ’·t (min) + θ’ [Formula 5] L AB (mg / cm 2 ) = α’·T (℃) + β’ In Formula 4, 0 < δ’ ≤ 5, and −300 ≤ θ’ < 0. In Formula 5, 0 < α’ ≤ 0.05, and 0 < β’ ≤ 0.5. In Formulas 4 and 5, L AB is the amount of cleaning, and T and t are as defined in Formulas 1 and 2. The amount of cleaning may satisfy the following formula 6. [Formula 6] L AB (mg / cm 2 ) = ν·T (℃) + ω·t (min) + γ’ In Formula 6, 0 < ν’ ≤ 0.05, 0 < ω’ ≤ 0.1, and −50 ≤ γ’ < 0. L AB , T, and t are as defined in Formulas 4 and 5. The amount of cleaning may satisfy the following formula 6-1. [Formula 6-1] L AB (mg / cm 2 ) = 0.01T (℃) + 0.02t (min) + γ’ In Formula 6-1, −50 ≤ γ’ < 0. L AB , T, and t are as defined in Formulas 4 and 5. The amount of cleaning is the sum of the first cleaning amount in the pickling step and the second cleaning amount in the alkali cleaning step. The first cleaning amount is 30 wt% or more and 40 wt% or less based on the total weight of the amount of cleaning, and the second cleaning amount can be 60 wt% or more and 7 wt% or less based on the total weight of the amount of cleaning. The step of providing the initial window includes the steps of providing a base glass and strengthening the provided base glass, wherein the base glass may be LAS (Lithium Alumino-Silicate) glass or NAS (Sodium Alumino-Silicate) glass. The step of strengthening the base glass may be a step of chemical strengthening with a toughening molten salt containing at least one of KNO3 and NaNO3. The step of strengthening the base glass may be carried out at a temperature of 350°C to 450°C. The pickling step may be a step of providing a pickling solution containing at least one of nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl). The alkaline cleaning step may be a step of providing an alkaline cleaning solution containing at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

[0009] A window manufacturing method according to one embodiment comprises the steps of providing a chemically strengthened initial window, an acid pickling step of cleaning the initial window with an acid pickling solution to provide an intermediate window, and an alkaline cleaning step of cleaning the intermediate window with an alkaline cleaning solution to provide a window, wherein the first compressive stress value of the initial window and the second compressive stress value of the window satisfy the following relationships of Equations 1 and 2. [Formula 1] ΔCS(MPa) = δ·t(min) + θ [Formula 2] ΔCS(MPa) = α·T(℃) + β In equation 1, 0 < δ ≤ 10, -300 ≤ θ < 0, 1 ≤ t ≤ 20; in equation 2, 0 < α ≤ 10, 0 < β ≤ 50, 40 ≤ T ≤ 70; and in equations 1 and 2, ΔCS is the absolute value of the difference between the first compressive stress value and the second compressive stress value.

[0010] The intermediate window may include voids formed by the dissolution of alkali metals from the initial window. The intermediate window may include a base layer in which the silicon content ratio to alkali metal is substantially the same as that of the silicon content ratio to alkali metal in the initial window, and an intermediate layer formed on the surface of the base layer in which the silicon content ratio to alkali metal ions is higher than that of the base layer. The proportion of voids in the intermediate layer may be higher than the proportion of voids in the basic layer. The thickness of the initial window is 500 μm or more and 800 μm or less, and the thickness of the intermediate layer may be 0.2 μm or more and 0.5 μm or less. The aforementioned window may be formed by removing the intermediate layer of the intermediate window. The absolute value of the difference between the first compressive stress value and the second compressive stress value is proportional to the amount of cleaning, and the amount of cleaning may be the weight difference between the initial window and the window. The washing amount may satisfy the following equations 4 and 5. [Formula 4] L AB (mg / cm 2 ) = δ'·t(min)+θ' [Formula 5] L AB (mg / cm 2 ) = α'·T(℃)+β' In equation 4, 0 < δ' ≤ 5 and -300 ≤ θ' < 0; in equation 5, 0 < α' ≤ 0.05 and 0 < β' ≤ 0.5; and in equations 4 and 5, L AB is the washing amount, and T and t are as defined in equations 1 and 2 above. The difference between the first compressive stress value and the second compressive stress value can satisfy the following equation 3-1. [Formula 3-1] ΔCS(MPa) = 4T(℃) + 2t(min) + γ In equation 3-1, -150 ≤ γ ≤ -50, and ΔCS, T, and t are as defined in equations 1 and 2. [Effects of the Invention]

[0011] According to the window manufacturing method of the present invention, the pickling step can be controlled by presenting the relationship between the process temperature and the change in compressive stress value with respect to the process holding time in the pickling step, and the washing step can be easily controlled considering the final physical properties of the window by presenting the relationship between the process conditions and the amount of washing in the washing step. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of an electronic device according to one embodiment. [Figure 2] Figure 1 is an exploded perspective view of the electronic device shown. [Figure 3] This is a perspective view showing a window according to one embodiment. [Figure 4] This is a cross-sectional view showing a window according to one embodiment. [Figure 5] This is a flowchart illustrating a simplified window manufacturing method according to one embodiment. [Figure 6] This is a flowchart illustrating a simplified window manufacturing method according to one embodiment. [Figure 7a] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 7b] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 7c] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 7d] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 7e] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 7f] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 7g] This is a schematic cross-sectional view illustrating the steps of a window manufacturing method according to one embodiment. [Figure 8a] This graph shows the change in the amount of washing in relation to the process temperature during the pickling step. [Figure 8b] This graph shows the change in the amount of cleaning in relation to the process temperature during the alkaline cleaning step. [Figure 9] This graph shows the relationship between the amount of cleaning and the change in compressive stress value. [Figure 10] This graph compares the window intensity before and after the cleaning step. [Figure 11] This graph compares the window's breakage strength before and after the cleaning step. [Figure 12] This graph shows the impact strength of the window in relation to the change in compressive stress value. [Figure 13] This graph shows the change in compressive stress value with increasing pickling time at each pickling temperature. [Figure 14a] This graph shows the change in compressive stress value with respect to the process holding time during the pickling step. [Figure 14b] This graph shows the results of measuring the change in compressive stress value with respect to the process holding time during the pickling step under specific temperature conditions, along with the corresponding relationship. [Figure 15] This graph shows the results of measuring compressive stress values ​​in response to changes in process temperature during the pickling step, and the relationship between these values ​​and the amount of change. [Figure 16] This graph shows the amount of cleaning as the pickling time increases for each pickling temperature. [Figure 17] This graph shows the results of measuring the amount of washing relative to the process holding time in the pickling step under specific temperature conditions, along with the corresponding relationship. [Figure 18] This graph shows the results of measuring the amount of washing in response to changes in the process temperature during the pickling step, along with the corresponding relationship. [Modes for carrying out the invention]

[0013] Because the present invention can be modified in various ways and take on various forms, specific embodiments are illustrated in the drawings and described in detail herein. However, this should not be understood as limiting the present invention to any particular disclosure, but rather as including all modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0014] In this specification, when a component (or region, layer, part, etc.) is referred to as "on top of," "combined with," or "combined with" another component, it means that it is directly placed on top of, connected to, or combined with the other component, or that a third component may be placed between them.

[0015] On the other hand, in this specification, "directly arranged" means that there are no additional layers, films, regions, plates, etc. between one part and another. For example, "directly arranged" means that two layers or two members are arranged without using additional members such as adhesive members.

[0016] The same drawing symbol refers to the same component. Furthermore, in drawings, the thickness, proportions, and dimensions of components are exaggerated for the sake of effective explanation of the technical content.

[0017] "and / or" includes all combinations of one or more that are defined by the relevant configuration.

[0018] Terms such as "first," "second," etc., are used to describe various components, but the components are not limited to these terms. The terms are used solely for the purpose of distinguishing one structural element from other components. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. A singular expression includes plural expressions unless the context clearly indicates otherwise.

[0019] Furthermore, terms such as "below," "on the lower side," "above," and "on the upper side" are used to describe the relevant relationships of the configuration shown in the drawings. The terms are relative concepts and are described in reference to the directions shown in the drawings. In this specification, "placed on top of ~" indicates not only the top of any one member but also the bottom.

[0020] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art in the field to which the present invention pertains. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and, unless interpreted in an ideal or overly formal sense, as expressly defined herein.

[0021] Terms such as "includes" or "possesses" should be understood to mean that the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification exist, and do not preclude the existence or possibility of adding one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0022] Hereinafter, specific examples of embodiments for carrying out the window manufacturing method of the present invention will be described in detail with reference to the drawings.

[0023] Figure 1 is a perspective view showing an electronic device. Figure 1 is a perspective view of an electronic device according to one embodiment, and shows an example of an electronic device including a window manufactured by a window manufacturing method. Figure 2 is an exploded perspective view of the electronic device shown in Figure 1. Figure 3 is a perspective view showing a window according to one embodiment. Figure 4 is a cross-sectional view showing a window according to one embodiment.

[0024] An electronic device EA is a device that is activated by an electrical signal. The electronic device EA includes a variety of embodiments. For example, the electronic device EA includes tablets, notebooks, computers, smart televisions, and the like. In this embodiment, the electronic device EA is shown exemplary as a smartphone.

[0025] The electronic device EA displays an image IM in the direction of the third direction axis DR3 from a display surface IS parallel to the plane defined by the first direction axis DR1 and the second direction axis DR2. The display surface IS on which the image IM is displayed corresponds to the top surface (front surface) of the electronic device EA and corresponds to the top surface FS of the window CW. Furthermore, the electronic device EA has a three-dimensional shape with a predetermined thickness in the direction of the third direction axis DR3, which is perpendicular to the plane defined by the first direction axis DR1 and the second direction axis DR2.

[0026] On the other hand, in the electronic device EA of the embodiment shown in Figure 1, the display surface IS includes a display area DA and a non-display area NDA adjacent to the display area DA. The non-display area NDA is shown as being arranged surrounding the display area DA, but the embodiment is not limited to this. The display area DA is the part where the video IM is provided and corresponds to the active area AA of the electronic panel DP. The video IM includes not only dynamic video but also still images. In Figure 1, a date and weather window is shown as an example of a video IM.

[0027] In this embodiment, the upper (or front) and lower (or back) surfaces of each component are defined based on the direction in which the video IM is displayed. The upper and lower surfaces oppose each other with respect to the third directional axis DR3, and the normal directions of the upper and lower surfaces are parallel to the third directional axis DR3. On the other hand, the directions indicated by the first to third directional axes (DR1, DR2, DR3) are relative concepts and may be converted to other directions. Hereinafter, the first to third directions refer to the same drawing reference numerals in the directions indicated by the first to third directional axes (DR1, DR2, DR3).

[0028] The electronic device EA includes a window CW, an electronic panel DP, and a housing HAU. In the embodiment of the electronic device EA shown in Figures 1 and 2, the window CW and the housing HAU are coupled together to form the external appearance of the electronic device EA.

[0029] The upper surface FS of the window CW defines the upper surface of the electronic device EA as described above. The upper surface FS of the window CW includes the transmissive region TA and the bezel region BZA.

[0030] The transmission region TA is an optically transparent region. For example, the transmission region TA is a region with a visible light transmittance of approximately 90% or more.

[0031] The bezel region (BZA) is a region with relatively lower light transmittance compared to the transmission region (TA). The bezel region (BZA) defines the shape of the transmission region (TA). The bezel region (BZA) is adjacent to and surrounds the transmission region (TA).

[0032] The bezel region BZA has a predetermined color. The bezel region BZA covers the frequency variation region NAA of the electronic panel DP, blocking the peripheral region NAA from being visible from the outside. However, this is an illustrative illustration, and in the window CW according to this embodiment, the bezel region BZA may be omitted.

[0033] For example, the window CW is a tempered glass substrate. The window CW utilizes the light transmittance of the glass to provide a transparent area TA and, including its tempered surface, stably protects the electronic panel DP from external impacts.

[0034] The window CW is manufactured by the window manufacturing method according to this embodiment. The window manufacturing method according to this embodiment includes the steps of providing an initial window and cleaning the provided initial window, the initial window including a chemically strengthened glass substrate. In the window manufacturing method of this embodiment, the cleaning step includes a sequentially performed pickling step and an alkaline cleaning step. In the window manufacturing method of this embodiment, the process conditions of the cleaning step and the change in the compressive stress value of the window before and after cleaning satisfy a linear relationship. Thus, by using the linear relationship presented in this embodiment to derive the process conditions of the cleaning step that take into account the mechanical properties of the window that are ultimately required, the cleaning process can be easily controlled. A detailed explanation of the window manufacturing method of this embodiment will be given later.

[0035] The electronic panel DP is activated by an electrical signal. In this embodiment, the electronic panel DP is activated to display an image IM on the display surface IS of the electronic device EA. The image IM is provided to the user via a transparent area TA, and the user receives information via the image IM. However, this is an illustrative illustration, and the electronic panel DP may be activated to sense external inputs applied to its upper surface. External inputs include, but are not limited to, user touch, contact or proximity of intangible objects, pressure, light, or heat.

[0036] The display panel DP includes an active area AA and a peripheral area NAA. The active area AA is the area that provides the video IM. The transparent area TA superimposes at least a portion of the active area AA.

[0037] The peripheral area NAA is the area covered by the bezel area BZA. The peripheral area NAA is adjacent to the active area AA. The peripheral area NAA surrounds the active area AA. The peripheral area NAA contains drive circuits and drive wiring for driving the active area AA.

[0038] An electronic panel (DP) includes multiple pixels (PX). Each pixel (PX) displays light in response to an electrical signal. The light displayed by the pixels (PX) embodies an image (IM). Each pixel (PX) includes a display element. For example, the display element may be an organic light-emitting element, a quantum point light-emitting element, a liquid crystal capacitor, an electrophoretic element, or an electrolyzed element.

[0039] The housing (HAU) is positioned beneath the electronic panel (DP). The housing (HAU) contains a material with relatively high rigidity. For example, the housing (HAU) includes multiple frames and / or plates made of glass, plastic, or metal. The housing (HAU) provides a predetermined housing space. The electronic panel (DP) is housed within this housing space and protected from external impacts.

[0040] Figure 3 is a perspective view showing window CW-a according to one embodiment. Compared to window CW of the embodiment shown in Figure 2, window CW-a of the embodiment shown in Figure 3 includes a bending section BA that is bent around the bending axis BX. In this embodiment, window CW-a includes a flat section FA and a bending section BA.

[0041] In this embodiment, the bending axis BX extends along the second directional axis DR2 and is provided on the lower surface RS side of window CW-a. The flat portion FA is the portion parallel to the plane defined by the first directional axis DR1 and the second directional axis DR2. The bending portion BA is a curved portion having a curved shape adjacent to the flat portion FA. For example, referring to Figure 3, the bending portion BA is the portion adjacent to both sides of the flat portion FA and bent downward from the flat portion FA. However, the embodiment is not limited to this, and the bending portion BA may be located adjacent to only one side of the flat portion FA, or adjacent to all four sides of the flat portion FA on the plane.

[0042] On the other hand, the shape of the window manufactured by the window manufacturing method according to this embodiment is not limited to those shown in Figures 2 and 3. For example, the window is a folding window that is folded or unfielded around a folding axis. In other words, the window manufacturing method described later can be used to manufacture windows with a variety of shapes.

[0043] Figure 4 is a cross-sectional view of a window CW according to one embodiment. The window CW according to this embodiment includes a tempered glass substrate BS and a bezel layer BZ. The tempered glass substrate BS is optically transparent. In this specification, the tempered glass substrate BS refers to a substrate provided by strengthening a base glass by the window manufacturing method of this embodiment, which will be described later, and cleaning the strengthened base glass.

[0044] The upper surface FS of the tempered glass substrate BS is exposed to the outside of the electronic device EA and defines the upper surface FS of the window CW and the upper surface of the electronic device EA. The lower surface RS of the tempered glass substrate BS faces the upper surface FS in the direction of the third directional axis DR3.

[0045] The bezel layer BZ is positioned on the lower surface RS of the tempered glass substrate BS and defines the bezel region BZA. The bezel layer BZ has a relatively lower light transmittance compared to the tempered glass substrate BS. For example, the bezel layer BZ has a predetermined color. Thereafter, the bezel layer BZ selectively transmits or reflects only light of a specific color. Alternatively, for example, the bezel layer BZ is a light-blocking layer that absorbs incident light. The color of the bezel region BZA is determined according to the light transmittance of the bezel layer BZ.

[0046] The bezel layer BZ is formed on the lower surface RS of the tempered glass substrate BS by printing or deposition. In this case, the bezel layer BZ is formed directly on the lower surface RS of the tempered glass substrate BS. Alternatively, the bezel layer BZ is bonded to the lower surface RS of the tempered glass substrate BS via a separate adhesive material. In this case, the adhesive material comes into contact with the lower surface RS of the tempered glass substrate BS.

[0047] Figures 5 and 6 are flowcharts illustrating a simplified window manufacturing method according to one embodiment. Figures 7a to 7g are cross-sectional views illustrating the steps of a window manufacturing method according to one embodiment.

[0048] The window manufacturing method of this embodiment includes the step S100 of providing an initial window and the step S300 of cleaning the provided initial window. The cleaning step S300 also includes the step S310 of pickling the provided initial window with acid and the step S330 of alkaline cleaning the pickled initial window. The pickling step S310 and the alkaline cleaning step S330 are performed sequentially.

[0049] The initial window CW-P is supplied to window CW after the cleaning step S300. During the cleaning step S300, a portion of the surface FS-P of the initial window CW-P is removed, thereby reducing the second compressive stress value in window CW compared to the first compressive stress value of the initial window CW-P. On the other hand, the defects DFS of the surface FS-P of the initial window CW-P are removed in the cleaning step S300, and the mechanical properties of window CW after the cleaning step S300, such as surface strength and impact resistance, are improved compared to the initial window CW.

[0050] In the window manufacturing method of this embodiment, step S100, which provides an initial window, includes step S110, which provides a base glass, and base glass strengthening step S130, which strengthens the provided base glass.

[0051] In one embodiment of the window manufacturing method, the base glass provided in step S110 is manufactured by a float process. Alternatively, the provided base glass may be manufactured by a down draw process or a fusion process. However, the embodiment is not limited to these, and the provided base glass may be manufactured by a variety of methods not exemplified.

[0052] The base glass provided in step S110 is cut and provided before the tempering step S130, taking into account its intended use. However, the embodiment is not limited thereto, and the provided base glass may be provided in a size that does not match the size of the product to which it will ultimately be applied, and may be later cut and processed to the applicable size of the final product after the window manufacturing process of this embodiment.

[0053] The base glass is flat. Alternatively, the base glass can be bent. For example, a base glass cut to the size of the final product to which it will be applied may be bent so as to bulge or sink in relative to its center. Or, the base glass may include a bent portion in its outer perimeter. However, the embodiments are not limited to these, and the base glass can be provided in a variety of shapes.

[0054] The base glass provided in step S100 is LAS-based glass or NAS-based glass. For example, the base glass contains SiO2, Al2O3, and Li2O3. More specifically, the base glass contains 50 wt% to 80 wt% of SiO2, 10 wt% to 30 wt% of Al2O3, and 3 wt% to 20 wr% of Li2O3. In one embodiment, the base glass also contains SiO2, Al2O3, Li2O3, and Na2O. On the other hand, in addition to SiO2, Al2O3, Li2O3, and Na2O, the base glass further contains at least one of P2O5, K2O, MgO, and CaO. However, the embodiments are not limited to these, and any commercial glass can be used without limitation as the base glass in these embodiments.

[0055] The base glass strengthening step S130 is a step of chemically strengthening the base glass by providing it with a strengthening molten salt. Specifically, the base glass strengthening step S130 is a step of immersing the base glass in the strengthening molten salt and strengthening the surface of the base glass by an ion exchange method. The strengthening molten salt provided to the base glass contains one or more alkali ions.

[0056] The base glass strengthening step S130 is performed by replacing alkali metal ions with relatively small ionic radii on the surface of the base glass with alkali metal ions with larger ionic radii. For example, Li on the surface of the base glass + or Na + These ions are provided from the strengthened molten salt, respectively. + or K + Surface strengthening is performed by exchanging ions or the like. The window manufactured after the base glass strengthening step S130 has a compressive stress region on its surface. The compressive stress region is formed on at least one of the upper and lower surfaces of the base glass.

[0057] The strengthening molten salt provided from the base glass strengthening step S130 is a mixed salt or a single salt. A mixed salt is Li + na + , K + , Rb + , and Cs + It is a molten salt containing two or more ions selected from the group consisting of the following. Furthermore, a single salt is Li + na + , K + , Rb + , and Cs + It is a molten salt containing any one ion selected from the group consisting of the following. For example, the enhancement step of the window production method of one embodiment includes a molten salt of KNO3 and NaNO3 as a mixed salt, and a molten salt of KNO3 as a single salt.

[0058] The base glass strengthening step S130 is performed at a temperature between 350°C and 450°C. However, the embodiments are not limited to this, and the process temperature in the strengthening step S130 is adjusted according to the type of strengthening molten salt used.

[0059] The base glass provided in the base glass provision step S110 described above is provided to the initial window CW-P after undergoing the base glass strengthening step S130.

[0060] Figure 7a shows the initial window provisioning step. Figure 7b is a cross-sectional view showing a portion of the initial window. Figure 7b is a cross-sectional view showing an enlarged view of the "AA" region in Figure 7a.

[0061] In the window manufacturing method according to this embodiment, the initial window CW-P refers to the glass substrate from the strengthening step S130 onward. The initial window CW-P has a predetermined thickness t CWP The initial window CW-P after the strengthening step S130 contains an alkali metal oxide such as Na2O or K2O. For ease of explanation, alkali metal ions IN are shown as circles in this specification.

[0062] The initial window CW-P formed in the base glass strengthening step S130 includes a compressive stress layer formed adjacent to the surface FS-P, and the initial window CW-P exhibits a first compressive stress value in the region adjacent to the surface FS-P.

[0063] On the other hand, the initial window CW-P contains multiple defects DFS formed on the surface FS-P. The defects DFS of the initial window CW-P are scratches formed on the surface of the initial window CW-P or recessed portions from the surface FS-P. The defects DFS are formed during the process of forming the initial window CW-P or during the process of moving the initial window CW-P, by collision with the outside or contact with the external environment.

[0064] Furthermore, the surface FS-P of the initial window CW-P may have foreign matter SS attached to it. Foreign matter SS contains substances different from the initial window CW-P and may include organic and / or inorganic materials. Foreign matter SS is attached during the process of forming the initial window CW-P or during the process of moving the initial window CW-P.

[0065] The roughness of the initial window CW-P's surface FS-P may vary depending on the number or shape of the defects DFS formed on the surface FS-P. On the other hand, defects DFS formed on the outer surface FS-P of the initial window CW-P reduce the fracture strength of the initial window CW-P. In other words, defects DFS are areas where cracks may occur or cracks may be easily transmitted when external impacts are applied to the initial window CW-P, and thus defects DFS may reduce the impact and fracture strength of the initial window CW-P.

[0066] Thickness t where a defect DFS is formed on the cross-section DF The initial window thickness t CWP It is formed more finely compared to [another method]. For example, the thickness t of the DFS in which the defect is formed. DF The thickness is approximately 0.2 μm to 0.5 μm. On the other hand, the thickness t of the initial window CW-P is CWP It is 300 μm or more. For example, the thickness of the initial window CW-P. CWP The size is between 500 μm and 800 μm.

[0067] The provided initial window CW-P is supplied to window CW via the cleaning step S300. The cleaning step S300 includes the pickling step S310 and the alkaline cleaning step S330. Figures 7c to 7f show areas corresponding to area AA' in Figure 7b for ease of explanation. Figures 7c and 7d correspond to cross-sectional views of the pickling step S310, and Figures 7e and 7f correspond to cross-sectional views of the alkaline cleaning step S330. Figure 7g is a cross-sectional view showing the window supplied via the pickling step S310 and the alkaline cleaning step S330.

[0068] Referring to Figures 7c and 7d, the pickling step S310 is a step in which the initial window CW-P is provided to an acidic environment. An acidic environment means an environment with a hydrogen ion concentration (hydrogen exponent, hereafter referred to as pH) index of less than 7, and if it is acidic, it can be provided in various forms such as liquid, gas, or solid.

[0069] In the window manufacturing method of this embodiment, the pickling step S310 is performed by providing the pickling solution WS1 to the initial window CW-P. The pickling solution WS1 according to one embodiment of the present invention is a strong acid with a pH of 2 or less. For example, the pickling solution WS1 contains at least one of nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl). On the other hand, the pH index of the pickling solution WS1 is measured to be about 2.5 or less at room temperature.

[0070] The pickling solution WS1 reacts with the initial window CW-P, forming an intermediate layer L2 within the initial window CW-P. As a result, as shown in Figure 7d, the initial window CW-P is divided into an intermediate window CW-C, which consists of an intermediate layer L2 and a base layer L1, after the pickling step S310. The intermediate layer L2 is a surface layer located on top of the base layer L1 and is exposed to the outside. The intermediate layer L2 is formed surrounding the surface of the base layer L1.

[0071] The intermediate layer L2 is a layer in which at least some of the alkali metal ions IN from the initial window CW-P have been removed by reaction with the pickling solution WS1. In this process, voids PO are defined at the locations where the alkali metal ions IN were removed. Hydrogen ions provided by the pickling solution WS1 are also placed at the locations where the alkali metal ions IN were removed. As a result, the intermediate layer L2 of the intermediate window CW-C after the pickling step S310 exhibits porous properties compared to the base layer L1. Furthermore, the density of the intermediate layer L2 is lower than that of the base layer L1.

[0072] In the pickling step S310, alkali metal ions IN are removed, resulting in a higher silicon content in the intermediate layer L2 than in the base layer L1. The silicon content ratio to alkali metal ions in the intermediate layer L2 is higher than the silicon content ratio to alkali metals in the base layer L1. In other words, the intermediate layer L2 becomes a Si-rich layer compared to the base layer L1.

[0073] The silicon content ratio to alkali metals within the base layer L1 substantially corresponds to the silicon content ratio to alkali metal ions within the initial window CW-P. Therefore, in the pickling step S310, only the density of the intermediate layer L2, which contains defects DFS adjacent to the surface FS-P, is reduced, so that the portion containing defects DFS is effectively removed.

[0074] Thickness t of the intermediate layer L2 L2 The thickness t is such that at least the defect DFS shown in Figure 7b is formed. DF It is formed to be the same as or greater than the thickness of the intermediate layer L2. For example, the thickness t of the intermediate layer L2 L2 The particle size is approximately 0.2 μm to 0.5 μm. As a result, the intermediate layer L2 is removed by subsequently performing an alkaline cleaning step S330, etc., which ensures that defects (DFS) are also stably removed.

[0075] Figures 7e to 7g show the steps for producing window CW via the alkaline washing step S330. The alkaline washing step S330 is a step in which the intermediate window CW-C is provided to a basic environment. The basic environment means an environment with a pH greater than 7, and can be provided in various forms such as liquid, gas, or solid, as long as it is basic.

[0076] In the window manufacturing method of this embodiment, the alkaline cleaning step S330 is performed by providing the alkaline cleaning solution WS2 to the intermediate window CW-C. The alkaline cleaning solution WS2 according to one embodiment of the present invention is a strong base with a pH of 13 or higher. For example, the alkaline cleaning solution WS2 contains sodium hydroxide (NaOH) or potassium hydroxide (KOH).

[0077] The alkaline cleaning solution WS2 reacts with the intermediate window CW-C, causing the intermediate layer L2 to be removed from the intermediate window CW-C. By finally removing the intermediate layer L2 formed in the pickling step S310 in the alkaline cleaning step S330, a window CW from which defects DFS have been removed from the surface FS-P can be formed. That is, defects DFS and foreign matter SS that were present in the initial window CW-P are removed from the base layer L1 along with the intermediate layer L2.

[0078] As a result, window CW has a surface (top surface) FS that is free from residual defects DFS and foreign matter SS. The surface FS of window CW substantially corresponds to the surface of the base layer L1. The surface roughness of window CW is in the range of 0.2 nm to 3 nm. The surface roughness of window CW is lower than the surface roughness of the initial window CW-P and the intermediate window CW-C.

[0079] After the pickling step S310 and the alkaline washing step S330, the window CW finally provided has a predetermined thickness t CW It has a thickness t of the window CW. In this embodiment, the thickness t CW The initial window thickness t CWP Smaller than. Window CW thickness t CW This corresponds to the thickness of the base layer L1 in the intermediate window CW-C.

[0080] In the window manufacturing method of this embodiment, the cleaning amount corresponds to the weight removed in cleaning step S330 from the portion adjacent to the surface FS-P of the initial window CW-P. The cleaning amount is measured as the amount removed per unit area, and in this specification, the unit of cleaning amount is "mg / cm²". 2 "

[0081] Figures 8a and 8b are graphs showing the amount of cleaning in relation to the process temperature for each cleaning step. Figure 8a shows the amount of cleaning in the pickling step S310, and Figure 8b shows the amount of cleaning in the alkaline cleaning step S330. The amount of cleaning in the alkaline cleaning step S330 shown in Figure 8b represents the amount of cleaning when the pickling step S310 is performed at the same temperature, followed by the alkaline cleaning step S330. In Figures 8a and 8b, the process holding time for each cleaning step is fixed at 10 minutes.

[0082] In Figures 8a and 8b, "y" corresponds to the washing amount, "x" is the process temperature, and "R 2 This corresponds to the coefficient of determination. Referring to Figures 8a and 8b, it can be seen that the amount of cleaning in each cleaning step increases in proportion to the temperature of the cleaning step. However, it can be seen that the amount of cleaning in the alkaline cleaning step is larger than the amount of cleaning in the pickling step.

[0083] In the window manufacturing method of this embodiment, the total cleaning amount is represented by the sum of the first cleaning amount in the pickling step and the second cleaning amount in the alkaline cleaning step. Under the conditions of the window manufacturing method of this embodiment, the first cleaning amount is 30 wt% to 40 wt% of the total weight of the final cleaning amount, and the second cleaning amount is 60 wt% to 70 wt% of the total weight of the final cleaning amount. For example, approximately 1 / 3 of the total cleaning amount is the cleaning amount in the pickling step, and approximately 2 / 3 of the total cleaning amount is the cleaning amount in the alkaline cleaning step.

[0084] The window CW ultimately provided by the window manufacturing method of this embodiment includes a compressive stress layer adjacent to the surface FS, and the window CW exhibits a second compressive stress value in the region adjacent to the surface FS.

[0085] In the window manufacturing method of this embodiment, the difference between the first compressive stress value of the initial window CW-P and the second compressive stress value of the window CW after the cleaning step satisfies the following equations 1 and 2.

[0086] [Formula 1] ΔCS(MPa) = δ·t(min) + θ

[0087] [Formula 2] ΔCS(MPa) = α·T(℃) + β

[0088] In equations 1 and 2 above, ΔCS is the absolute value of the difference between the first compressive stress value and the second compressive stress value, T is the temperature of the pickling step, and t is the holding time of the pickling step. ΔCS corresponds to {(first compressive stress value) - (second compressive stress value)}.

[0089] In equations 1 and 2 above, the unit of the difference in compressive stress values ​​of ΔCS is "MPa", the variable of the relationship equation, the temperature T of the pickling step, is entered in "°C", and the process time t of the pickling step is entered in "min (minutes)".

[0090] In the following, the same definitions as those given in Equations 1 and 2 above apply to ΔCS (MPa), T (°C), and t (min) used in the relational equations described herein. Furthermore, in this specification, the absolute value of the difference between the first compressive stress value and the second compressive stress value has the same meaning as the difference between the first and second compressive stress values, and is also used in the same sense as the change in compressive stress value. That is, both the difference between the first and second compressive stress values ​​and the change in compressive stress value are represented by ΔCS.

[0091] Equation 1 above is a linear relationship showing the relationship between the process holding time t in the pickling step and the change in compressive stress value ΔCS. In Equation 1, 0 < δ ≤ 10 and -300 ≤ θ < 0. On the other hand, Equation 2 is a linear relationship showing the relationship between the process temperature T in the pickling step and the change in compressive stress value ΔCS. In Equation 2, 0 < α ≤ 10 and 0 < β ≤ 50.

[0092] On the other hand, Figure 9 is a graph showing the relationship between the amount of cleaning and the compressive stress value of a window manufactured by the window manufacturing method of one embodiment. In Figure 9, "ΔCS" is the change in the compressive stress value, and "L AB」 is the cleaning amount, and 「R 2 」 corresponds to the coefficient of determination. The change amount ΔCS of the compression stress value corresponds to the difference between the compression stress value in the region adjacent to the surface FS-P of the initial window CW-P and the compression stress value in the region adjacent to the surface FS of the window CW in the window manufacturing method described with reference to FIGS. 7a to 7g. In the window manufactured by the window manufacturing method according to an embodiment of the present invention, the change amount ΔCS of the compression stress value and the cleaning amount L AB satisfy the following relational expression. In the following relational expression A, G is a stress reduction coefficient, and 0 < G ≦ 1000. Z is a constant value, and -50 < Z ≦ 50.

[0093] [Equation A] ΔCS = G · L AB + Z

[0094] In FIG. 9, the relationship between the cleaning amount and the change amount of the compression stress value is measured and shown. Since the relational expression ΔCS = 172.48 · L AB + 17.762 is derived, it can be seen that the window manufactured by the window manufacturing method according to the present embodiment satisfies the relationship of the above formula A. That is, the change amount of the compression stress in the window manufacturing method of the present embodiment is linearly proportional to the cleaning amount. Therefore, by adjusting the cleaning amount in the cleaning step of the window manufacturing method of the present embodiment, the compression stress value of the window can be finally controlled.

[0095] On the other hand, the window manufactured by the window manufacturing method of the present embodiment exhibits improved strength characteristics. FIGS. 10 and 11 are graphs showing the measurement of the change in the strength characteristics of the window before and after the cleaning step, respectively.

[0096] In FIGS. 10 and 11, 「before cleaning (ref)」 is the result for the initial window CW, and 「after cleaning」 is the result for the window CW after the cleaning step S300 has been performed.

[0097] Figure 10 shows a comparison of BOR strengths. BOR strength is evaluated using the BOR (Ball on Ring) test method. The initial window CW-P and window CW, which are the test subjects, were placed on a circular ring of a predetermined size (a ring with a diameter of 30 mm and a radius of R of 2.5 mm, with an outermost diameter of 35 mm and an innermost diameter of 25 mm). A spherical test probe with a diameter of 10 mm was brought into contact with the initial window and the window, respectively, and the strength at which the initial window or the window broke was measured while applying a load. In the measurement, the strength at which the window broke is indicated by the BOR strength N.

[0098] Referring to the results in Figure 10, the average BOR strength before cleaning was 383.5 N, and the average BOR strength after cleaning was measured at 626.6 N, indicating that the strength characteristics of the window improved after the cleaning step. The window used for evaluation in Figure 10 was pickled at 65°C for 10 minutes and then alkaline cleaned at 65°C for 10 minutes.

[0099] On the other hand, the BOR strength of a window manufactured by the window manufacturing method of this embodiment is 500N or more. For example, the BOR strength of a window manufactured by the window manufacturing method of this embodiment is 500N or more and 1000N or less.

[0100] Figure 11 shows the results of the drop test. The results in Figure 11 were measured using a mock-up sample of the electronic device, including the window. In Figure 11, "Before cleaning (ref)" refers to the results for the mock-up of the electronic device, including the initial window CW-P, which had not undergone the cleaning step, and "After cleaning" refers to the results for the mock-up of the electronic device, including the window CW. The window CW used for evaluation in Figure 11 was pickled at 65°C for 10 minutes and then alkaline cleaned at 65°C for 10 minutes.

[0101] The drop test was conducted by dropping a model sample of an electronic device onto a granite substrate to check for damage. The measurements shown in Figure 11 indicate the drop height at which the window of the model electronic device was damaged. The drop height was increased by 10 cm increments, starting at 60 cm.

[0102] Referring to the results in Figure 11, the average drop height before cleaning was 70 cm, and the average drop height after cleaning was 130 cm. It was confirmed that the strength measured in the drop test was improved by approximately 1.8 times in the windows that underwent the cleaning process. In other words, it was confirmed that the window manufacturing method of this embodiment provides windows with improved impact resistance by including a cleaning step that includes an acid pickling step and an alkaline cleaning step.

[0103] Figure 12 is a graph showing the impact strength of the window against the change in compressive stress value. In Figure 12, the BDT strength (cm) corresponds to the evaluation result of the steel ball drop test, which is an impact resistance evaluation method. In the steel ball drop test, a 150g steel ball was dropped onto the window, and the height at which the window broke was measured for evaluation.

[0104] Referring to the results in Figure 12, it can be seen that the BDT strength improves with increasing ΔCS (change in compressive stress), but the degree of increase in BDT strength is small when ΔCS is greater than 120. It can be seen that when ΔCS is 120 or less, the BDT value increases approximately linearly with increasing ΔCS, and when ΔCS is greater than 120, the ΔCS value saturates.

[0105] In other words, in the window manufacturing method of this embodiment, the BDT strength of the window can be improved by changing the compressive stress value by performing a cleaning step, and it can be seen that the degree of improvement in impact resistance due to the cleaning process is particularly high when ΔCS is 120 or less.

[0106] As described above, the difference ΔCS between the first compressive stress value of the initial window and the second compressive stress value of the window after the cleaning step satisfies the relationship between Equations 1 and 2 above, and is linearly proportional to the temperature T of the pickling step and the process holding time t of the pickling step, respectively. By optimizing the temperature T and time t of the pickling step, the final compressive stress value obtained for the window can be acquired. That is, by optimizing the temperature T and time t of the pickling step, a window with the required impact resistance and fracture strength can be manufactured.

[0107] The window manufacturing method of this embodiment provides a window with improved impact resistance and fracture strength by performing a cleaning step including an acid pickling step and an alkaline cleaning step. On the other hand, the final compressive stress value of the window can be predicted by using the relationship between the change in compressive stress value (the absolute value of the difference between the first compressive stress value and the second compressive stress value) presented herein and the process temperature and process time of the acid pickling step. Furthermore, by using the relationship between the change in compressive stress value and the process temperature and process time of the acid pickling step presented herein, it is possible to easily specify and control the cleaning conditions required to obtain the strength characteristics desired for the final provided window.

[0108] The change in compressive stress value, ΔCS, satisfies the relationship between Equations 1 and 2 as described above, and ΔCS is proportional to the temperature T of the pickling step and the holding time t of the pickling step, respectively. Therefore, by using the relationship between Equations 1 and 2 presented herein, the change in compressive stress value, ΔCS, can be controlled by adjusting the temperature T of the pickling step or the holding time t of the pickling step.

[0109] On the other hand, ΔCS, which is the change in compressive stress value, is proportional to the combination of the temperature T of the pickling step and the holding time t of the pickling step. That is, ΔCS, which is the change in compressive stress value, can be expressed by a linear relationship in which both the temperature T of the pickling step and the holding time t of the pickling step are variables.

[0110] The relationship between ΔCS, which is the change in compressive stress value, the temperature T of the pickling step, and the holding time t of the pickling step satisfies the following equation 3.

[0111] [Formula 3] ΔCS(MPa)=ν·T(℃)+ω·t(min)+γ

[0112] In equation 3 above, 0 < ν ≤ 10, 0 < ω ≤ 20, and -150 ≤ γ ≤ -50.

[0113] For example, the difference between the first compressive stress value and the second compressive stress value satisfies equation 3-1 below.

[0114] [Formula 3-1] ΔCS(MPa) = 2T(℃) + 4t(min) + γ

[0115] In equation 3-1 above, the constant γ is such that -150 ≤ γ ≤ -50.

[0116] Figures 13 to 18 below are graphs showing the difference between the first and second compressive stress values ​​depending on the conditions of the cleaning step in the window manufacturing method of this embodiment. Figures 13 to 18 show the difference in compressive stress values ​​depending on the process conditions of the pickling step among the cleaning steps described above, and sulfuric acid solution is used as the pickling solution. However, the relational formula presented in the embodiment of the present invention, which will be explained below with reference to Figures 13 to 18, is not limited to the case where sulfuric acid solution is used, but is also applicable when a strong acid solution is used as the pickling solution.

[0117] Figure 13 is a graph showing the change in compressive stress value with respect to increasing pickling time at each pickling temperature. In Figure 13, "Measured Values" are the measured changes in compressive stress value at the relevant process temperature and process time, while "Calculated Values" are the values ​​calculated by inputting the process temperature and process time into the following formula 3-1a and shown in the graph.

[0118] [Formula 3-1a] ΔCS(MPa) = 2T(℃) + 4t(min) - 10⁸

[0119] In Figure 13, the pickling temperature conditions were set to 50°C, 60°C, and 65°C, respectively, and the process time was set to 1 to 20 minutes, showing both measured and calculated values.

[0120] Referring to Figure 13, it can be seen that, under the conditions of pickling temperature 50°C to 65°C and process holding time 1 minute to 20 minutes, the values ​​calculated from the relationship 3-1a presented herein are similar to the measured values. That is, the relationship between the difference between the first and second compressive stress values ​​presented herein and the temperature of the pickling step and the process holding time of the pickling step can be used to predict the actual cleaning process.

[0121] In the window manufacturing method of the embodiment described with reference to Figures 5 to 7g, the process temperature T in the pickling step S310 is 40°C or higher and 70°C or lower. At temperatures below 40°C, the reactivity between the pickling solution WS1 and the initial window CW-P decreases, and the cleaning process does not proceed smoothly. At temperatures above 70°C, organic matter contained in the pickling solution WS1 may vaporize into fume, which can cause problems with the stability of the cleaning process. In the above pickling step S310, the process holding time t is 1 minute (min) or higher and 20 minutes (min) or lower.

[0122] Figure 14a is a graph showing the change in compressive stress value ΔCS with respect to the process holding time t in the pickling step S310. Figure 14a shows the change in compressive stress value with respect to the washing time at a pickling temperature of 65°C. Referring to Figure 14a, it can be confirmed that the change in compressive stress value increases as the process holding time increases.

[0123] A washing time of 1 minute corresponds to the minimum washing time required for minimal cleaning. Furthermore, if the pickling process is held for more than 20 minutes, the effect of improving the strength of the window due to the passage of washing time does not increase. In other words, referring to Figure 14a, the change in compressive stress value during washing times exceeding 20 minutes is not as large as the change in compressive stress value during washing times up to 20 minutes. Therefore, considering the properties of the substrate during the process, it is preferable to perform the pickling process with a pickling time of 20 minutes or less.

[0124] Furthermore, if the pickling process is carried out for more than 20 minutes, the ΔCS value will increase to 120 MPa or more. However, considering the results shown in Figure 12 above, the improvement in impact strength due to the increase in the ΔCS value is negligible. Therefore, the appropriate processing time for the pickling step is between 1 minute and 20 minutes.

[0125] Figure 14b is a graph showing the results of measuring the change in compressive stress value ΔCS with respect to the process holding time t in the pickling step under specific temperature conditions, and the related equation. In Figure 14b, the difference in compressive stress value ΔCS with respect to the pickling process time t is measured when the process temperature T in the pickling step S310 is fixed at 50°C, 60°C, and 65°C, respectively, and the related equation is derived and shown. The pickling process time t is set to between 1 minute and 20 minutes.

[0126] The graph of measured values ​​shown in Figure 14b satisfies the relationship described in Equation 1 above. That is, from the process holding time of the pickling step and the change in compressive stress value derived from the measurement results shown in Figure 14a, it can be confirmed that there is a linear relationship between the holding time of the pickling step and the change in compressive stress value under the same process temperature conditions.

[0127] For example, the relationship between the process holding time t at a process temperature of 50°C and the change in compressive stress value ΔCS is given by the following equation 1-a. Equation 1-a corresponds to the case where δ is 2.4 and θ is 2.3 in the above equation 1.

[0128] [Formula 1-a] ΔCS(MPa) = 2.4t + 2.3

[0129] Furthermore, the process holding time t and the change in compressive stress value ΔCS at process temperatures of 60°C and 65°C are related by the following equations 1-b and 1-c, respectively.

[0130] [Formula 1-b] ΔCS(MPa) = 4.3t + 15

[0131] [Formula 1-c] ΔCS(MPa) = 5t + 19

[0132] Equation 1-b corresponds to the case in Equation 1 where δ is 4.3 and θ is 15, and Equation 1-c corresponds to the case in Equation 1 where δ is 5 and θ is 19. Equations 1-a to 1-c are relationships that satisfy the process time t within the range of 1 minute to 20 minutes.

[0133] From equations 1 and 1-a to 1-c described above, it is confirmed that the change in the compressive stress value of the window manufactured by the window manufacturing method of this embodiment can be controlled by adjusting the process holding time of the pickling step at a predetermined temperature. That is, since the change in the compressive stress value corresponds to the difference between the first compressive stress value of the initial window and the second compressive stress value of the window, the cleaning step can be performed by controlling the process temperature and process holding time of the pickling step, taking into account the final compressive stress value of the window.

[0134] Figure 15 is a graph showing the results of measuring the change in compressive stress value ΔCS with respect to a change in process temperature T, while fixing the process holding time t of the pickling step S310 in one embodiment of the window manufacturing method, and the relationship equations thereto. In Figure 15, the difference in compressive stress value with respect to a change in pickling process time T is measured while the process holding time t of the pickling step is fixed at 10 minutes and 20 minutes, respectively, and the relationship equations derived from these are shown. The measurement results shown in Figure 15 were measured within the process temperature range of 30°C to 70°C for the pickling step.

[0135] The graph of the measured values ​​shown in Figure 15 satisfies the relationship described in Equation 2 above. From the measured values ​​of the process temperature and the change in compressive stress value in the pickling step derived from the measurement results shown in Figure 15, it can be confirmed that there is a linear relationship between the temperature and the change in compressive stress value in the pickling step for the same process holding time.

[0136] For example, the relationship between the process temperature T and the change in compressive stress value ΔCS during a process holding time of 10 minutes is given by the following equation 2-a.

[0137] [Formula 2-a] ΔCS(MPa) = 2T - 66

[0138] Furthermore, the relationship between the process temperature T and the change in compressive stress value ΔCS during a process holding time of 20 minutes is given by the following equation 2-b.

[0139] [Formula 2-b] ΔCS(MPa)=6.5T-295

[0140] Equation 2-a corresponds to the case in Equation 2 where α is 2 and β is -66, and Equation 2-b corresponds to the case in Equation 2 where α is 6.5 and β is -295. Equations 2-a and 2-b are relational expressions that are satisfied when the process temperature is in the range of 40°C to 70°C.

[0141] From equations 2, 2-a, and 2-b described above, it is confirmed that the change in the compressive stress value of the window manufactured by the window manufacturing method of this embodiment can be controlled by adjusting the process temperature of the pickling step within a predetermined process holding time. That is, since the change in the compressive stress value corresponds to the difference between the initial first compressive stress value of the window and the second compressive stress value of the window, the cleaning step can be performed by controlling the process temperature and process holding time of the pickling step, taking into account the final compressive stress value of the window.

[0142] As explained in Figure 9 above, in a window manufactured using the window manufacturing method of this embodiment, the difference in compressive stress values ​​before and after the cleaning step is proportional to the amount of cleaning in the window cleaning step. In the window manufacturing method of the embodiment described with reference to Figures 5 to 7g, the amount of cleaning is the amount of material removed per unit area from the surface FS-P of the initial window CW-P. For example, in one embodiment, the amount of cleaning is the amount of material removed from the intermediate layer L2 of the intermediate window CW-C. Also, the amount of cleaning corresponds to the weight difference between the initial window CW-P and the window CW.

[0143] In the window manufacturing method of this embodiment, the washing amount LAB and the process conditions of the pickling step satisfy the following equations 4 and 5.

[0144] [Formula 4] L AB (mg / cm 2 ) = δ'·t(min)+θ'

[0145] [Formula 5] L AB (mg / cm 2 ) = α'·T(℃)+β'

[0146] In equations 4 and 5 above, L AB L is the washing amount, T is the temperature of the pickling step, and t is the holding time of the pickling step. AB This corresponds to the weight removed during the process of processing from the initial window CW-P to the window CW-P. In equations 4 and 5 above, the washing amount L AB The unit is "mg / cm 2 The variables in the relation are entered in units of °C for the temperature T of the pickling step and in units of min (minutes) for the process time t of the pickling step.

[0147] The L used in the relational formulas described herein below AB (mg / cm 2 For ), T(°C), and t(min), the same definitions as those given in equations 4 and 5 above apply.

[0148] Equation 4 above represents the process holding time t of the pickling step and the amount of washing L. AB This is a linear relationship showing the relationship between the process temperature T of the pickling step and the amount of washing L. In equation 4 above, 0 < δ' ≤ 5 and -300 ≤ θ' < 0. On the other hand, equation 5 above shows the process temperature T of the pickling step and the amount of washing L. AB This is a linear relation that shows the relationship between the two. In equation 5 above, 0 < α' ≤ 0.05 and 0 < β' ≤ 0.5.

[0149] Washing volume L AB The amount of cleaning L is proportional to the temperature T of the pickling step and the holding time t of the pickling step, respectively. Therefore, by using the relationships of Equations 4 and 5 presented herein, the amount of cleaning L can be adjusted by adjusting the temperature T of the pickling step or the holding time t of the pickling step. AB It can be controlled. Also, the washing volume L AB Using the proportional relationship between the amount of compressive stress ΔCS and the amount of cleaning L, AB By controlling this, the surface compressive stress value of the window CW can be changed, thereby improving the impact strength of the window.

[0150] On the other hand, the washing volume L AB The amount of washing L is proportional to the combination of the temperature T of the pickling step and the holding time t of the pickling step. AB This can be expressed as a linear relationship where the temperature T of the pickling step and the holding time t of the pickling step are both variables.

[0151] Washing volume L AB The temperature T of the pickling step and the holding time t of the pickling step satisfy the relationship shown in Equation 6 below.

[0152] [Formula 6] L AB (mg / cm 2 ) = ν·T(℃) + ω·t(min) + γ'

[0153] In equation 6 above, 0 < ν' ≤ 0.05, 0 < ω' ≤ 0.1, and -50 ≤ γ' < 0.

[0154] For example, washing volume L ABThe temperature T of the pickling step and the holding time t of the pickling step satisfy the following equation 6-1.

[0155] [Formula 6-1] L AB (mg / cm 2 ) = 0.01T(℃) + 0.02t(min) + γ'

[0156] In equation 6-1 above, the constant γ' is -50 ≤ γ < 0.

[0157] Figure 16 shows the relationship between the amount of washing L and the increase in pickling time at each pickling temperature. AB This graph shows the results. In Figure 16, "Measured Value" is the washing volume L at the relevant process temperature and process time. AB The "measured values" are shown, while the "calculated values" are graphs showing the values ​​calculated by inputting the process temperature and process time into the following formula 6-1a.

[0158] [Formula 6-1a] L AB (mg / cm 2 ) = 0.01T(℃) + 0.02t(min) - 0.583

[0159] In Figure 16, the pickling temperature conditions were set to 50°C, 60°C, and 65°C, respectively, and the process time was set to 1 to 20 minutes, with measured and calculated values ​​shown.

[0160] Referring to Figure 16, it can be seen that the values ​​calculated using the relational equation 6-1a presented herein are similar to the measured values ​​under the conditions of pickling temperature 50°C to 65°C and process holding time 1 minute to 20 minutes. In other words, the relational equations presented herein between the amount of cleaning, the temperature of the pickling step, and the process holding time of the pickling step can be used to predict the actual cleaning process.

[0161] Figure 17 shows the washing amount L as a function of the process holding time t in the pickling step under specific temperature conditions. ABThis graph shows the measured values ​​and the corresponding relationship. Figure 17 shows the washing amount L as a function of the pickling process time t, with the process temperature T in the pickling step S310 fixed at 50°C, 60°C, and 65°C, respectively. AB The measured values ​​are shown, and the resulting relationship equations are derived and presented. The pickling process time t is set to 1 to 20 minutes.

[0162] The graph of the measured values ​​shown in Figure 17 satisfies the relationship described in Equation 4 above. That is, from the process holding time and washing amount of the pickling step derived from the measurement results shown in Figure 17, it can be confirmed that there is a linear relationship between the holding time and washing amount of the pickling step under the same process temperature conditions.

[0163] For example, process holding time t and washing amount L at a process temperature of 50°C. AB This is related to the following equation 4-a. Equation 4-a corresponds to the case in equation 4 above where δ' is 0.01 and θ' is -0.005.

[0164] [Formula 4-a] L AB (mg / cm 2 ) = 0.01t - 0.005

[0165] Furthermore, the process holding time t and washing amount L at process temperatures of 60°C and 65°C. AB These have the following relationships, as shown in equations 4-b and 4-c.

[0166] [Formula 4-b] L AB (mg / cm 2 ) = 0.02t + 0.05

[0167] [Formula 4-c] L AB (mg / cm 2 ) = 0.02t + 0.1

[0168] The above formula 4-b corresponds to the case where in the above formula 4, δ' is 0.02 and θ' is 0.05, and the above formula 4-c corresponds to the case where in the above formula 4, δ' is 0.02 and θ' is 0.1. The above formulas 4-a to 4-c are relational expressions satisfied within the range where the process time t is 1 minute or more and 20 minutes or less.

[0169] It is confirmed that the cleaning amount of the window manufactured by the window manufacturing method of the present embodiment from the above-described formulas 4 and 4-a to 4-c is controlled by adjusting the process holding time in the pickling step at a predetermined temperature. That is, since the cleaning amount is proportional to the change amount of the compressive stress value, which is the difference between the first compressive stress value and the second compressive stress value of the window, the cleaning step can be performed by controlling the process temperature and the process holding time in the pickling step in consideration of the finally required compressive stress value of the window.

[0170] FIG. 18 is a graph showing the relationship between the cleaning amount L with respect to the change in the process temperature T while fixing the process holding time t in the pickling step S310 in the window manufacturing method of an embodiment. AB and the relational expression therefor. In FIG. 18, the measured values of the cleaning amount L with respect to the change in the pickling process temperature T are shown in a state where the process holding time t in the pickling step is fixed at 10 minutes and 20 minutes, respectively, and the relational expression derived therefrom is shown. The measurement results shown in FIG. 18 are the results measured within the range of the process temperature of 30°C to 70°C in the pickling step. AB

[0171] The graph of the measured values shown in FIG. 18 satisfies the relationship of the above-described formula 5. From the process temperature and the cleaning amount L in the pickling step derived from the measurement results shown in FIG. 18 AB values, it is confirmed that there is a linear relational expression between the temperature and the cleaning amount L in the pickling process at the same process holding time. AB

[0172] For example, the process temperature T and the cleaning amount L at the process holding time of 10 minutes AB have the relationship of the following formula 5-a.

[0173] [Formula 5-a] L​​AB (mg / cm 2 ) = 0.008T - 0.245

[0174] Also, the process temperature T and the cleaning amount L at a process holding time of 20 minutes AB have the relationship of the following formula 5-b.

[0175] [Formula 5-b] L AB (mg / cm 2 ) = 1.3T + 0.37

[0176] The above formula 5-a corresponds to the case where α' is 0.008 and β' is -0.245 in the above formula 5, and the above formula 5-b corresponds to the case where α' is 1.3 and β' is 0.37 in the above formula 5. The above formula 5-a and formula 5-b are relational expressions that are satisfied within the range where the process temperature is 40°C or higher and 70°C or lower.

[0177] It is confirmed that the cleaning amount of the window manufactured by the window manufacturing method of the present embodiment from the above-described formulas 5, 5-a, and 5-b is controlled by adjusting the temperature of the pickling step at a predetermined process holding time. That is, since the cleaning amount is proportional to the change amount of the compressive stress value, which is the difference between the first compressive stress value and the second compressive stress value of the window, the cleaning step can be performed by controlling the process temperature and the process holding time of the pickling step in consideration of the finally required compressive stress value of the window.

[0178] The window manufacturing method of the present embodiment includes a pickling step and an alkali cleaning step that are sequentially performed, thereby making it possible to provide a window having improved strength characteristics and impact resistance. Further, the present embodiment incorporates a relational expression between the process temperature and the process holding time of the cleaning step and the cleaning amount, or a relational expression between the process temperature and the process holding time of the cleaning step and the change amount of the compressive stress value, so that the cleaning process for providing a window having excellent impact resistance and mechanical strength can be easily controlled.

[0179] In other words, the window manufacturing method of this embodiment incorporates a pickling step and systematically manages the cleaning process by using a relational expression for the change in compressive stress value with respect to the temperature and process holding time of the pickling step, taking into account the physical properties ultimately required for the window, thereby improving the economic efficiency of the process.

[0180] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the embodiments described above, and can be modified and implemented in various ways without departing from the technical spirit of the present invention. [Explanation of symbols]

[0181] AA Active Area BA Bending Section BS tempered glass substrate BX Bending Axis BZ Bezel Layer BZA Bezel Area CW, CW-a window CW-P Initial Window CW-C Intermediate Window DA display area DFS defect DP Electronic Panel EA electronic equipment FA flat area FS window surface (top surface) FS-P initial window surface HAU enclosure IM video IN alkali metal ions IS display surface NAA Shuhen Area NDA Hidden Area PO Void PX pixels RS bottom surface SS Foreign object TA transmission area WS1 pickling solution WS2 Alkaline Cleaning Solution

Claims

1. The steps include providing an initial window having a first compressive stress value, The process includes a cleaning step of cleaning the initial window to provide a window having a second compressive stress value, The aforementioned cleaning step is The pickling step involves pickling the initial window, The process includes an alkaline cleaning step of alkaline cleaning the acid-pickled initial window, The absolute value of the difference between the first compressive stress value and the second compressive stress value satisfies ΔCS in the following equation 3-1a. A window manufacturing method characterized in that the cleaning step is a step in which the ΔCS in the following formula 3-1a is controlled to be 120 or less. [Formula 3-1a] ΔCS (MPa) = 2T (℃) + 4t (min) - 108 In formula 3-1a, T is the temperature of the pickling step, t is the holding time of the pickling step, and the words in parentheses represent the following units of the corresponding parameters. The unit of ΔCS is megapascal (MPa), the unit of T is Celsius (°C), and the unit of t is minutes (min). The holding time t in the pickling step is 1 minute or more and less than 20 minutes. The temperature T of the pickling step is 50°C or higher and 65°C or lower.

2. The difference between the first compressive stress value and the second compressive stress value is proportional to the amount of cleaning in the cleaning step. The window manufacturing method according to claim 1, characterized in that the cleaning amount is the amount of the initial window removed per unit area from the surface of the initial window.

3. The window manufacturing method according to claim 2, characterized in that the amount of washing satisfies the following formula 6-1a. [Formula 6-1a] L ＡＢ (mg / cm ２ )=0.01T(℃)+0.02t(min)-0.583 In formula 6-1a, LAB is the washing amount, and mg / cm² (milligrams / square centimeter) in parentheses represents the unit of LAB.

4. The washing amount is the sum of the first washing amount in the pickling step and the second washing amount in the alkaline washing step. The first washing amount is 30 wt% or more and 40 wt% or less based on the total weight of the washing amount. The window manufacturing method according to claim 2, characterized in that the second washing amount is twice the first washing amount.

5. The step of providing the initial window is, The steps include providing the base glass, The step of strengthening the provided base glass, The window manufacturing method according to claim 1, characterized in that the base glass is LAS (Lithium Aluminum-Silicate) glass or NAS (Sodium Aluminum-Silicate) glass.

6. The step of strengthening the base glass is KNO ３ and NaNO ３ The window manufacturing method according to claim 5, characterized by the step of chemically strengthening with a strengthening molten salt containing at least one of the following.

7. The window manufacturing method according to claim 6, characterized in that the step of strengthening the base glass is performed at a temperature of 350°C or higher and 450°C or lower.

8. The aforementioned pickling step involves nitric acid (HNO ３ ), sulfuric acid (H ２ SO ４ The window manufacturing method according to claim 1, characterized by the step of providing an pickling solution containing at least one of the following: ), and hydrochloric acid (HCl).

9. The window manufacturing method according to claim 1, characterized in that the alkaline cleaning step is a step of providing an alkaline cleaning solution containing at least one of sodium hydroxide (NaOH) and potassium hydroxide (KOH).

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