JP2013087031A - Method for producing cover glass for portable device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a cover glass for portable devices capable of improving dimensional accuracy of a glass substrate after chemical reinforcing treatment.SOLUTION: The method for producing the cover glass for portable devices includes a chemical reinforcing step of performing chemical reinforcing of the glass substrate by bringing the glass substrate 100 into contact with a chemical reinforcing treatment liquid to perform ion exchange of a part of ions in the glass substrate 100 with ions in the chemical reinforcing treatment liquid having an ionic radius larger than the ions in the glass substrate. The chemical reinforcing of the glass substrate 100 is carried out under a chemical reinforcing condition giving a chemically reinforced glass substrate 100 having a dimension coinciding with the demanded dimension of the cover glass for portable device based on the dimension of the glass substrate 100 before chemical reinforcing treatment.

Description

  The present invention relates to a method for manufacturing a cover glass for a mobile device used for protecting a display screen of a mobile terminal device such as a mobile phone, a smartphone, or a PDA (Personal Digital Assistant).

  In a portable terminal device such as a mobile phone, a smartphone, or a PDA, a transparent protective plate is disposed outside the display device in order to protect the display device such as a liquid crystal. As the protective plate, a resin such as acrylic is often used. However, since the protective plate made of resin is easy to bend, it is necessary to increase the thickness of the plate or to leave a large gap with the display device.

  Therefore, in order to protect the display device of the portable terminal device, it is preferable to use a cover glass made of a glass material. Since glass has high hardness, there is little bending and it can contribute to thickness reduction.

  In general, a cover glass is manufactured by extracting a plurality of glass substrates of an arbitrary shape from a large single plate-like glass and processing the extracted glass substrates. Thereby, productivity higher than the case where one cover glass is manufactured one by one is obtained. As a method for extracting a glass substrate from plate-like glass, not only machining but also a method using etching is known (for example, Patent Document 1).

  In Patent Document 1, a plate-like glass having a resist pattern formed on the main surface is etched with an etchant, and a glass substrate having a desired shape is extracted from the plate-like glass. By forming the outer shape by etching in this way, the end surface becomes a mirror surface and has very high smoothness, and microcracks that are inevitably generated in machining are not generated. For this reason, the high intensity | strength calculated | required by the cover glass for portable terminals can be obtained. Further, there is an advantage that even a complicated shape difficult to machine can be easily processed by etching.

  However, since glass has the property of breaking, it is necessary to improve the strength. On the other hand, Patent Document 2 proposes to chemically strengthen the extracted glass substrate by ion exchange after extracting the outer shape of the cover glass. According to Patent Document 2, it is said that a cover glass for a portable terminal that is suppressed in bending and hardly damaged can be manufactured by chemically strengthening and forming an ion exchange layer on which a compressive stress acts. Patent Document 2 describes that chemical strengthening is performed at a temperature of 400 ° C. to 550 ° C. using a chemical strengthening treatment liquid such as potassium nitrate or sodium nitrate for chemical strengthening.

JP 2009-167086 A JP 2007-99557 A

  By the way, with the increase in demand for portable devices, the demand for cover glasses for portable devices is also increasing rapidly. Under such a background, the cover glass for mobile devices is required not only to increase the strength but also to have higher dimensional accuracy, for example, to protect the display screen of the mobile device. In order to satisfy such a requirement, the present inventors extracted a small glass substrate from the plate-like glass and then chemically strengthened it to produce a cover glass for portable devices. However, the produced cover glass for portable devices has a problem that it may not satisfy the desired dimensions required as a product.

  An object of this invention is to provide the manufacturing method of the cover glass for portable devices which can improve the dimensional accuracy of the glass substrate after chemical strengthening in view of said subject.

  The present inventors diligently studied to solve the above problems. As a result, it has been found that in the chemical strengthening step of immersing the glass substrate in a high-temperature chemical strengthening treatment liquid, the dimensions of the glass substrate increase according to the state of the chemical strengthening treatment liquid, that is, the chemical strengthening conditions. As a result of further studies, the present inventors have found that the above-mentioned problems can be solved by determining the chemical strengthening conditions based on the dimensions of the glass substrate before chemical strengthening, and have completed the present invention.

  In order to solve the above-described problems, a typical configuration of a method for manufacturing a cover glass for a portable device according to the present invention is to bring a glass substrate into contact with a chemical strengthening treatment liquid, thereby including a part of the glass substrate. A method for manufacturing a cover glass for a portable device comprising a chemical strengthening step of chemically strengthening a glass substrate by ion exchange of ions with ions in a chemical strengthening treatment liquid having an ion radius larger than that of the ions. Based on the dimensions of the glass substrate before the process, the glass substrate is chemically strengthened under a chemical strengthening condition in which the dimension of the glass substrate after the chemical strengthening process becomes a dimension required for the cover glass for portable devices.

  Here, the dimension of the cover glass for portable devices required as a product is determined for each product. However, due to the chemical strengthening conditions in the chemical strengthening process, the dimensions of the glass substrate change.

  So, according to the said structure, based on the dimension of the glass substrate before a chemical strengthening process, the chemical strengthening conditions that the dimension of the glass substrate after a chemical strengthening process becomes a dimension calculated | required by the cover glass for portable devices are determined. . Furthermore, the dimensional accuracy of the glass substrate after chemical strengthening is improved by performing chemical strengthening under the determined chemical strengthening conditions.

  Know the correspondence between the chemical strengthening conditions and the amount of change in the dimensions of the glass substrate that has been chemically strengthened under the chemical strengthening conditions, and refer to the correspondence based on the dimensions of the glass substrate before the chemical strengthening process. Thus, it is preferable to determine the chemical strengthening conditions. In this case, first, the difference from the target dimension of the glass substrate after the chemical strengthening process is grasped from the dimension of the glass substrate before the chemical strengthening process. Next, by referring to the correspondence relationship between the chemical strengthening conditions and the amount of change in the size of the glass substrate, the amount of change in the size of the glass substrate in the chemical strengthening process is almost the same as the difference from the target size. Strengthening conditions can be determined. By performing chemical strengthening under the determined chemical strengthening conditions, the dimensional accuracy of the glass substrate after chemical strengthening can be improved.

  Prior to the chemical strengthening step, the shape processing step of processing into a glass substrate in the shape of a cover glass for portable devices by isotropic etching of the plate glass using a resist pattern formed on the main surface of the plate glass In the chemical strengthening step, it is preferable to determine the chemical strengthening conditions based on the dimensions of the glass substrate after the shape processing step, with the dimensions of the glass substrate after the shape processing step as the dimensions of the glass substrate before the chemical strengthening step. In this case, since the glass substrate is extracted from the sheet glass by isotropic etching, unlike the machining, microcracks are not generated, and high strength required for the cover glass for portable terminals can be obtained.

  The glass substrate is an aluminosilicate glass containing Li ions, and the chemical strengthening condition is preferably the concentration of Li ions contained in the chemical strengthening treatment liquid. In this case, the aluminosilicate glass performs chemical strengthening by exchanging Li ions contained in the glass with Na ions and exchanging Na ions with K ions. Therefore, the higher the concentration of Li ions contained in the chemical strengthening treatment liquid, the more fatigued the chemical strengthening treatment liquid, and the smaller the degree of chemical strengthening. Therefore, for example, the smaller the desired dimension of the glass substrate after isotropic etching, the lower the Li ion concentration, thereby increasing the degree of ion exchange during chemical strengthening and Dimensional elongation can be increased. Thus, the dimensional accuracy of the glass substrate after chemical strengthening can be improved.

  The chemical strengthening condition is preferably a time for bringing the glass substrate into contact with the chemical strengthening treatment liquid. In this case, for example, if the contact time is increased, the degree of ion exchange during chemical strengthening can be increased, and the elongation of the dimension of the glass substrate due to chemical strengthening can be increased. If the contact time is shortened, the degree of ion exchange at the time of chemical strengthening can be lowered, and the elongation of the glass substrate due to chemical strengthening can be reduced. Thus, the dimensional accuracy of the glass substrate after chemical strengthening can be improved.

  The chemical strengthening condition is preferably the temperature of the chemical strengthening treatment solution. In this case, for example, if the temperature is increased, the degree of ion exchange at the time of chemical strengthening can be increased, and the elongation of the dimension of the glass substrate due to chemical strengthening can be increased. Also, if the temperature is lowered, the degree of ion exchange during chemical strengthening can be lowered, and the elongation of the glass substrate due to chemical strengthening can be reduced. Thus, the dimensional accuracy of the glass substrate after chemical strengthening can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the cover glass for portable devices which can improve the dimensional accuracy of the glass substrate after chemical strengthening can be provided.

It is a figure explaining the glass substrate to which the manufacturing method of the cover glass for portable devices in this embodiment is applied. It is a functional block diagram of the manufacturing system of the cover glass for portable devices in this embodiment. It is a figure which shows the cross section of the glass substrate extracted by isotropic etching.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a view for explaining a glass substrate to which a method for manufacturing a cover glass for a portable device in the present embodiment is applied. The glass substrate 100 is used as a cover glass for a portable device (hereinafter referred to as a cover glass) that protects a display screen of a mobile terminal. The glass substrate 100 has a plate shape having a rectangular outer portion 102. The glass substrate 100 is provided with an opening 104 for a microphone or a speaker. The glass substrate 100 becomes a cover glass by performing decoration such as printing as necessary. Since the cover glass is attached to a frame of a portable terminal and the like to protect the display screen, not only strength but also high dimensional accuracy is required.

  In the present embodiment, when manufacturing the cover glass, paying attention to the change in the size of the glass substrate in the chemical strengthening step described later, the size of the glass substrate after the chemical strengthening is a desired target size required as a product and It aims at obtaining such high dimensional accuracy. A cover glass manufacturing system capable of performing a series of steps including a chemical strengthening step will be described below.

  FIG. 2 is a functional block diagram of a system for manufacturing a cover glass for portable devices in the present embodiment. In the figure, thick arrows indicate the flow of manufacturing, and thin arrows indicate the flow of information. The manufacturing system 110 extracts the small glass substrate from the large sheet glass 120, and then chemically strengthens the glass substrate 100 used for the cover glass. The manufacturing system 110 includes an etching processing device 130, a chemical strengthening treatment tank 140, a strengthening condition determining device 150, a grasping device 160, and a memory 170 that stores a table.

  The sheet glass 120 is formed directly from a molten glass into a sheet shape, or a glass body molded to a certain thickness is molded to a predetermined thickness, and the main surface is polished to a predetermined thickness. Things can be used. In particular, when molding directly from molten glass into a sheet, it is preferable because the main surface of the sheet glass 120 is in a surface state free from microcracks. Examples of the method for directly forming a sheet from molten glass include a downdraw method and a float method. Moreover, you may form plate glass by a press method.

Examples of the plate glass 120 include aluminosilicate glass, soda lime glass, borosilicate glass, and the like, and aluminosilicate glass is more preferable from the viewpoint of forming a strong compressive stress. Among _them, it is preferable that the aluminosilicate glass containing _{SiO 2, Al 2 O 3,} Li 2 O and / or Na ₂ O. Al ₂ O ₃ is useful for improving ion exchange performance in chemical strengthening described later. Li ₂ O is a component for ion exchange with Na + ions in chemical strengthening. Na ₂ O is a component for ion exchange with K + ions in chemical strengthening. ZrO ₂ is useful for increasing the mechanical strength.

  The etching processing apparatus 130 performs an etching process of extracting a small glass substrate having a cover glass shape from the sheet glass 120 by isotropic etching. In the etching step, a resist pattern is formed on the main surface of the plate-like glass 120, and the resist pattern is used to etch with an etchant to form the outer shape and opening of the small glass substrate. By forming the outer shape and the opening by etching, the end face of the glass substrate and the inner wall surface of the opening have a very high smoothness on the mirror surface, and microcracks that are inevitably generated by machining are not generated, and the high required for the cover glass Strength can be obtained. Moreover, even a complicated shape difficult to machine can be easily processed.

  When forming a resist pattern, first, a resist material is coated on both main surfaces of the sheet glass 120. Any resist material may be used as long as it is resistant to an etchant used for etching. As an example, when the glass sheet 120 is etched by isotropic etching by wet etching (wet etching) of an aqueous solution containing hydrofluoric acid, a resist material having excellent hydrofluoric acid resistance can be used.

  Next, a photomask having a desired mask pattern is arranged in parallel with both main surfaces of the plate glass 120, and exposure is performed by irradiating light from both sides of the resist material. Here, the resist material is a negative type, and when exposed to light, the resist material changes in quality and does not dissolve in the developer. When the resist material after exposure is developed, a resist pattern is formed in a region other than the region to be etched (remaining region).

  The etchant used for wet etching may be any material that can etch the plate-like glass 120. For example, an acidic solution containing hydrofluoric acid as a main component or a mixed acid containing at least one of sulfuric acid, nitric acid, hydrochloric acid, and silicic hydrofluoric acid in hydrofluoric acid can be used.

  In the wet etching, the plate glass 120 is etched isotropically. Therefore, the region not masked by the resist pattern is dissolved so that the grooves are dug down from both sides, and eventually, the grooves on both sides are connected to each other at approximately the center of the plate thickness, so that the regions are separated and opened. In this way, the etching process by the etching processing apparatus 130 is performed.

  FIG. 3 is a view showing a cross section of a glass substrate extracted by isotropic etching. Here, the cross-sectional shape of the glass substrate 100A when the plate-like glass 120 is isotropically etched by wet etching is shown. In the drawing, resist masks 204a formed on both main surfaces of the glass substrate 100A are indicated by hatching. A dimension (width in the main surface direction) of the main surface of the resist mask 204a of the resist pattern formed in the exposure process using the photomask is indicated by La. Further, the thickness of the glass substrate 100A is indicated by Da as shown in the figure.

  As shown in FIG. 3, the end surface of the glass substrate 100A is formed with a protruding portion 106a whose central portion protrudes outward, and gently curves from the protruding portion 106a toward both main surfaces. Inclined surfaces 106b and 106c are formed as described above. In addition, it is preferable that the boundary between the inclined surfaces 106b and 106c and the main surface and the protruding portion 106a have a rounded shape with a radius of several tens of μm. By adopting such an end face shape, when the cover glass is attached to the frame or the like of the mobile terminal device, it can be easily attached without causing galling or chipping.

  Further, the outer dimension of the glass substrate 100A is defined by the distance between the protruding portions 106a and 106a on both end faces. Here, the external dimensions of the glass substrate 100A are indicated by Wa as shown in the figure.

  After etching, resist stripping is performed. For example, as a stripping solution for stripping the resist pattern from the glass substrate 100A, it is preferable to use an alkaline solution such as KOH or NaOH. Note that the types of the resist material, the etchant, and the stripping solution can be appropriately selected according to the material of the plate glass 120 that is the material to be etched.

  Next, the chemical strengthening process performed with respect to the glass substrate of the small piece after an etching process is demonstrated. The chemical strengthening treatment tank 140 shown in FIG. 2 performs chemical strengthening by ion exchange processing on the glass substrate extracted from the sheet glass 120 after the shape processing step by etching. Chemical strengthening is a process of further increasing mechanical strength by forming a compressive stress layer on the glass surface by exchanging ions on the surface of the glass with other ions having a large ionic radius. For the chemical strengthening, for example, a chemical strengthening treatment liquid such as potassium nitrate or sodium nitrate is used, and the treatment is performed at a temperature of 300 to 450 (° C.) for 1 to 30 hours. Thereby, Li + ions in the glass are exchanged with Na + ions in the chemical strengthening treatment liquid, and Na + ions in the glass are exchanged with K + ions in the chemical strengthening treatment liquid.

  The compressive stress layer formed by chemical strengthening may be 5 (μm) or more. Preferably, the thickness of the compressive stress layer is 35 (μm) or more, more preferably 50 (μm) or more, and still more preferably 100 (μm) or more. Moreover, the end surface of a glass substrate is also chemically strengthened by performing chemical strengthening after extracting a glass substrate. For this reason, when mounting the glass substrate 100 shown in FIG. 1 to a portable terminal device, it can suppress that the chip | tip and crack of the glass substrate 100 arise.

  The glass substrate after chemical strengthening is taken out from the chemical strengthening treatment tank 140, cooled in the air and water, and then washed to remove the molten salt and other deposits adhering to the glass substrate. It becomes the glass substrate 100 shown. As a cleaning method, a method of washing away with a cleaning solution such as water, a dipping method of immersing in a cleaning solution, a scrub cleaning method of contacting a rotating roll body with a glass substrate while flowing the cleaning solution, or the like can be used. The dipping method may be performed in a state where ultrasonic waves are applied to the cleaning liquid. Then, a cover glass is manufactured by giving decoration, such as printing, to the glass substrate 100 as needed.

  Here, the inventors focused on the fact that the outer dimensions of the glass substrate 100 change depending on the chemical strengthening conditions in the chemical strengthening step. In chemical strengthening, a compressive stress layer is formed on the glass surface by exchanging ions on the surface of the glass with other ions having a large ion radius. Since this compressive stress layer expands the glass substrate, the substrate size becomes large.

  That is, the dimensional change amount (degree of elongation) of the glass substrate 100 due to chemical strengthening varies depending on the chemical strengthening conditions accompanying the chemical strengthening. Therefore, a table showing the correspondence between the chemical strengthening conditions and the elongation of the outer dimensions of the glass substrate by chemical strengthening may be prepared. The correspondence relationship indicated by the table will be described in detail in Tables 1 and 2 of the embodiment.

  The table is stored in the memory 170 as shown in FIG. 2, and shows the correspondence between the chemical strengthening conditions accompanying chemical strengthening and the elongation of the outer dimensions of the glass substrate. As chemical strengthening conditions, for example, the concentration (ppm) of Li ions contained in the chemical strengthening treatment liquid, the immersion time (hour) which is the time for contacting the glass substrate with the chemical strengthening treatment liquid, the temperature of the chemical strengthening treatment liquid ( ° C).

  In the chemical strengthening step, Li ions contained in the glass substrate are exchanged with Na ions, and Na ions are exchanged with K ions. For this reason, the higher the concentration of Li ions contained in the chemical strengthening treatment liquid, the more the chemical strengthening treatment liquid becomes fatigued and the rate of ion exchange decreases, thereby reducing the degree of chemical strengthening. The Li concentration can be changed by exchanging the chemical strengthening treatment liquid, adding molten salt, or the like.

  Further, in the chemical strengthening step, the longer the immersion time and the higher the temperature of the chemical strengthening treatment liquid, the more the ion exchange proceeds, and the elongation of the outer dimensions of the glass substrate tends to increase. However, the above-mentioned tendency regarding time and temperature may not monotonously increase the outer dimension due to the stress relaxation phenomenon of the glass substrate. The temperature can be changed by adjusting the heater of the chemical strengthening treatment tank.

  Next, the flow of information in the manufacturing system 110 (see thin line arrows) will be described. The memory 170 storing the above-described table refers to the contents of the table in response to a request from the grasping device 160 shown in FIG. The grasping device 160 grasps the correspondence relationship between the chemical strengthening conditions associated with the chemical strengthening process and the elongation of the outer dimensions of the glass substrate from the table. Furthermore, the grasping device 160 refers to the correspondence relationship in response to a request from the strengthening condition determining device 150.

  The strengthening condition determination device 150 refers to the correspondence relationship of the table based on the dimensions of the glass substrate after the etching process by the etching processing device 130, and the outer dimension of the glass substrate after the chemical strengthening process is a desired outer dimension, that is, a product. The chemical strengthening conditions are determined so as to achieve the target dimensions required. Note that the target dimensions of the glass substrate may be appropriately stored in the memory 170, for example.

  Specifically, the strengthening condition determining device 150 acquires the outer dimensions of the glass substrate 100 after the etching process measured by a dimension measuring device (not shown), and further reads the target dimensions of the glass substrate from the memory 170. Thus, the difference between the outer dimension of the glass substrate 100 and the target dimension is grasped. The difference here assumes a shortage of the outer dimension relative to the target dimension.

  Subsequently, the strengthening condition determination device 150 refers to the table and selects and determines the chemical strengthening conditions for obtaining the dimensional change amount of the glass substrate that substantially matches the difference in the chemical strengthening step. And in the chemical strengthening processing tank 140, the glass substrate 100 is chemically strengthened on the determined chemical strengthening conditions. If it does in this way, the external dimension of the glass substrate after a chemical strengthening process will come to correspond substantially with a target dimension.

  In the chemical strengthening process, as shown in the table, the Li ion concentration, the immersion time of the glass substrate in the chemical strengthening treatment liquid, the temperature of the chemical strengthening treatment liquid, and the extension of the external dimensions of the glass substrate correspond to each. Have a relationship. For this reason, the strengthening condition determination device 150 changes not only one chemical strengthening condition among Li concentration, immersion time, and temperature, but also changes two or more chemical strengthening conditions selected from these groups, and the outer shape of the glass substrate. You may make it the external dimension of the glass substrate after chemical strengthening approach the target dimension by adjusting the extension of a dimension.

  Here, selection criteria for chemical strengthening conditions will be described. Since the concentration of Li ions affects the life of the chemical strengthening treatment liquid, if the concentration of Li ions is not adjusted in consideration of the life of the chemical strengthening treatment liquid, either the immersion time or the temperature is used as the chemical strengthening condition. Either one or both may be adjusted.

  In addition, since the end time of chemical strengthening changes by adjusting the immersion time, considering the time control of the entire manufacturing process, when the immersion time is not adjusted, the Li concentration and One or both of the temperatures may be adjusted.

  Furthermore, since the heating temperature is restricted by the usable temperature of the chemical strengthening treatment tank 140 and the chemical strengthening treatment liquid, when the heating temperature is not adjusted, either the Li concentration or the immersion time is used as the chemical strengthening condition. Or both may be adjusted.

  In the method for manufacturing a cover glass for mobile devices in the present embodiment as described above, the dimensions of the glass substrate before chemical strengthening are referred to by referring to the correspondence relationship between the chemical strengthening conditions accompanying chemical strengthening and the elongation of the outer dimensions of the glass substrate. Based on the above, the chemical strengthening conditions are determined. Therefore, the variation in the external dimension of the glass substrate before chemical strengthening is adjusted by chemical strengthening, and the dimensional accuracy of the glass substrate after chemical strengthening can be improved.

  The above adjustment can be similarly applied to the opening size of the glass substrate. Therefore, the variation of the opening dimension of the glass substrate before chemical strengthening can be adjusted by chemical strengthening, and the dimensional accuracy of the opening of the glass substrate is improved. In addition to this, by adjusting both the outer dimensions and opening dimensions of the glass substrate, the dimensional change that can occur between the outer peripheral end surface of the glass substrate and the inner wall surface of the opening can be reduced, and the positional deviation of the opening can be reduced. Therefore, the positional accuracy of the opening is improved.

[Example]
Examples of the present invention will be described below, but the present invention is not limited to the following examples.

  Examples 1 to 6 are examples showing experimental results for grasping the correspondence between chemical strengthening conditions and substrate dimensions. This correspondence corresponds to the table in the above embodiment.

Glass composition of the plate-like glass, and SiO ₂ of from 62.5 to 64.5 wt%, 13 to 15 and the weight% _Al 2 _{O 3,} and 5-7 wt% of Li ₂ O, 9.5 to 11 .5% by weight of Na ₂ O, is intended to include the ZrO ₂ 5-7 wt%.

  In the sample of this example, first, a resist was applied to both surfaces of a plate-like glass having the above composition, and exposure and development were performed using a predetermined photomask to form a resist pattern. Then, using this resist pattern as a mask, wet etching was performed on each plate glass using an etching solution for etching a glass material (an acidic solution containing hydrofluoric acid). A glass substrate was cut out from each plate glass by wet etching, and the remaining resist was removed and washed.

  Next, the substrate dimensions of the glass substrate were measured before the chemical strengthening step. The target dimensions required for the product in the rectangular glass substrate used for the cover glass for portable devices are the long side 101 (mm) and the short side 48 (mm). In this example, the short side dimension was measured. For the measurement, a CNC image measurement system “NEXIV” manufactured by Nikon Corporation was used.

  In Examples 1 to 3, the chemical strengthening step was performed under the conditions of 0 (ppm), 900 (ppm), and 1800 (ppm) of the Li concentration of the chemical strengthening treatment liquid. The chemical strengthening treatment liquid is a mixed salt of potassium nitrate and sodium nitrate, temperature 360 (° C.), and immersion time is 3 hours. Li concentration was measured by ion chromatography (ICS-2000 manufactured by Dionex). The exchange column used was CS-12A, and the eluent was methanesulfonic acid. After chemical strengthening, predetermined cleaning was performed, and the glass substrate dimensions were measured. The number of measured substrate dimensions is 10 for each of Examples 1-3. The results are shown in Table 1. The substrate dimension variation ratio in the table is a ratio for representing the amount of dimensional change of the glass substrate due to chemical strengthening. Moreover, a board | substrate dimension fluctuation ratio is a board | substrate dimension after chemical strengthening / the board | substrate dimension before chemical strengthening, and is the average value of 10 measured. All subsequent chemical strengthening is performed with a mixed salt of potassium nitrate and sodium nitrate, and the immersion time is 3 hours.

  Examples 4-6 used the glass substrate after the etching process created similarly to Examples 1-3. After measuring the dimensions of the glass substrate before the chemical strengthening step, the glass substrate was chemically strengthened under three conditions of 340 (° C.), 360 (° C.), and 380 (° C.). Here, the Li concentration is 900 (ppm). After chemical strengthening, predetermined cleaning was performed, and the glass substrate dimensions were measured. The number of measured substrate dimensions is the same as in Examples 1-3. The results are shown in Table 2. The board | substrate dimension fluctuation ratio in a table | surface is the board | substrate dimension after chemical strengthening / the board | substrate dimension before chemical strengthening, and is the average value of 10 measured.

  From Example 1 to Example 3 in Table 1, a correspondence relationship between the Li concentration of the chemical strengthening treatment liquid and the substrate dimension variation ratio was obtained. It can be seen that when the Li concentration of the chemical strengthening treatment solution is small, the elongation of the substrate dimension due to chemical strengthening increases, and when the Li concentration is large, the elongation of the substrate dimension decreases.

  Further, from Example 4 to Example 6 in Table 2, the correspondence relationship between the temperature of the chemical strengthening treatment liquid and the substrate dimension variation ratio was obtained. It can be seen that when the temperature of the chemical strengthening treatment solution is high, the elongation of the substrate dimension due to chemical strengthening increases, and when the temperature is low, the elongation of the substrate dimension decreases.

(Example)
In the examples, based on the dimensions of the glass substrate before the chemical strengthening step, the Li concentration of the chemical strengthening treatment liquid in Tables 1 and 2, the temperature of the chemical strengthening treatment liquid, and the elongation of the substrate dimensions of the glass substrate due to the chemical strengthening The chemical was strengthened by referring to the relationship.

  The Example measured the dimension of the glass substrate before a chemical strengthening process. And, the size of the glass substrate before the chemical strengthening process is sorted into three stages (sorting: less than 47.97 (mm), 47.97 (mm) or more and less than 4799 (mm), or 47.9 (mm) or more. )did.

  In Example 1, the glass substrate sorted according to the above dimensions was chemically strengthened by adjusting (selecting) the Li concentration with reference to Table 1. For glass substrates with large substrate dimensions before the chemical strengthening process, chemical strengthening is performed under conditions where the elongation of the substrate dimensions is small, and for glass substrates with small substrate dimensions before the chemical strengthening process, conditions for increasing the substrate dimension are large. With chemical strengthening. Specifically, a glass substrate having a substrate dimension of less than 47.97 (mm) was chemically strengthened at a Li concentration of 0 (ppm). The glass substrate having a substrate size of 47.97 (mm) or more and less than 47.99 (mm) was chemically strengthened at a Li concentration of 900 (ppm). Furthermore, a glass substrate having a substrate size of 47.99 (mm) or more was chemically strengthened at a Li concentration of 1800 (ppm). Here, the temperature of the chemical strengthening treatment liquid is 360 (° C.). Table 3 shows the dimensions of the glass substrate after chemical strengthening. The number of dimensional measurements of the glass substrate is 700 for every three stages of sorting, for a total of 2100.

  In Example 2, the glass substrate sorted according to the above substrate dimensions was chemically strengthened by adjusting (selecting) the temperature of the chemical strengthening treatment liquid with reference to Table 2. The glass substrate having a large dimension before the chemical strengthening process was chemically strengthened under a condition that the elongation was small, and the glass substrate having a small dimension before the chemical strengthening was chemically strengthened under a condition that the elongation was large. Specifically, a glass substrate having a substrate dimension of less than 47.97 (mm) was chemically strengthened at a temperature of 380 (° C.) of the chemical strengthening treatment liquid. Moreover, the glass substrate whose board | substrate dimension was 47.97 (mm) or more and less than 47.99 (mm) was chemically strengthened at 360 (degreeC). Further, a glass substrate having a substrate size of 47.99 (mm) or more was chemically strengthened at 340 (° C.). Here, the Li concentration of the chemical strengthening treatment liquid is 900 (ppm). Table 3 shows the dimensions of the glass substrate after chemical strengthening. The number of dimensional measurements of the glass substrate is 700 for every three stages of sorting, for a total of 2100.

(Comparative example)
In the comparative example, the glass substrates sorted according to the above dimensions are all chemically strengthened under the same chemical strengthening conditions, specifically, the Li concentration of the chemical strengthening treatment liquid is 900 (ppm) and the temperature of the chemical strengthening treatment liquid is 360 (° C.). did. Table 3 shows the dimensions of the glass substrate after chemical strengthening. The number of dimensional measurements of the glass substrate is 2100.

  From Table 3, based on the dimensions of the glass substrate before the chemical strengthening step, Example 1 in which the chemical strengthening conditions were adjusted with reference to the correspondence between the chemical strengthening conditions in Tables 1 and 2 and the changes in the dimensions of the glass substrate, and The standard deviation values of the dimensions of the glass substrate of Example 2 were 0.013 (mm) and 0.014 (mm). On the other hand, the standard deviation value of the glass substrate size of the comparative example in which the chemical strengthening was performed without referring to the correspondence relationship between the chemical strengthening condition and the change in the size of the glass substrate was 0.027 (mm). Therefore, it can be seen that Examples 1 and 2 have less variation than the comparative example.

  Thus, based on the dimensions of the glass substrate before the chemical strengthening process, in the example in which the chemical strengthening process was performed with reference to the previously known chemical strengthening conditions and the dimensional change amount of the glass substrate, the dimensional accuracy of the glass substrate was It was confirmed that it improved more.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  In particular, the measurement results of the short side dimension were shown in the examples, but in addition to this, the long side dimension and the opening dimension of the glass substrate were measured as necessary. The chemical strengthening condition may be determined with reference to the correspondence with the dimensional change amount of the glass substrate (the elongation of the dimension of the glass substrate) accompanying the chemical strengthening process of dimensions. Alternatively, the chemical strengthening conditions may be determined by combining a plurality of various dimensions and referring to the correspondence between the combination and the dimensional change amount of the glass substrate accompanying the chemical strengthening process of various dimensions.

  The present invention relates to protection of a display screen of a mobile device (portable electronic device) such as a mobile terminal device such as a mobile phone, a smartphone, or a PDA, or a digital still camera, or a cover glass for a mobile device used for a casing of the mobile device. It can be used for manufacturing methods.

DESCRIPTION OF SYMBOLS 100, 100A ... Glass substrate, 102 ... Outer part, 104 ... Opening, 106a ... Projection part, 106b, 106c ... Inclined surface, 110 ... Manufacturing system, 120 ... Sheet glass, 130 ... Etching processing apparatus, 140 ... Chemical strengthening process Tank, 150 ... Strengthening condition determination device, 160 ... Grasping device, 170 ... Memory

Claims (6)

By bringing the glass substrate into contact with the chemical strengthening treatment liquid, some ions contained in the glass substrate are ion-exchanged with ions in the chemical strengthening treatment liquid having an ionic radius larger than the ions. A method for manufacturing a cover glass for a portable device including a chemical strengthening step for chemically strengthening a substrate,
Based on the dimensions of the glass substrate before the chemical strengthening step, the glass substrate after the chemical strengthening step is chemically strengthened under the chemical strengthening conditions that are the dimensions required for the cover glass for portable devices. A method for manufacturing a cover glass for portable devices.   The correspondence relationship between the chemical strengthening condition and the amount of change in the dimension of the glass substrate chemically strengthened under the chemical strengthening condition is grasped in advance, and the correspondence relationship is based on the dimension of the glass substrate before the chemical strengthening step. The method for producing a cover glass for a portable device according to claim 1, wherein the chemical strengthening condition is determined with reference to FIG. Prior to the chemical strengthening step, isotropic processing of the sheet glass using a resist pattern formed on the main surface of the sheet glass to form a cover glass-shaped glass substrate for portable devices Including steps,
In the chemical strengthening step, the dimensions of the glass substrate after the shape processing step are taken as the dimensions of the glass substrate before the chemical strengthening step, and the chemical strengthening conditions are determined based on the dimensions of the glass substrate after the shape processing step. The manufacturing method of the cover glass for portable devices of Claim 1 or 2. The glass substrate is an aluminosilicate glass containing Li ions,
The said chemical strengthening conditions are the density | concentrations of Li ion contained in a chemical strengthening process liquid, The manufacturing method of the cover glass for portable devices of any one of Claims 1-3 characterized by the above-mentioned.   The said chemical strengthening conditions are the time which makes a glass substrate contact with a chemical strengthening process liquid, The manufacturing method of the cover glass for portable devices of any one of Claims 1-4 characterized by the above-mentioned.   The said chemical strengthening condition is the temperature of a chemical strengthening process liquid, The manufacturing method of the cover glass for portable devices of any one of Claims 1-5 characterized by the above-mentioned.

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