JP2013087030A - 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 comprises a shape forming step of forming sheet glass to a glass substrate having the form of the cover glass for portable devices by isotropic etching of the sheet glass and a chemical reinforcing step of performing chemical reinforcing of the glass substrate. A first correspondence relationship between the thickness of the sheet glass and the dimension of the glass substrate extracted by etching in the shape forming step, and a second correspondence relationship between the chemical reinforcing condition and the elongation of the dimension of the glass substrate caused by chemical reinforcing under the chemical reinforcing condition in the chemical reinforcing step are grasped beforehand, and the glass substrate is chemically reinforced in the chemical reinforcing step under a chemical toughening condition to make the dimension of the chemically reinforced glass substrate coincide with the demanded dimension of the cover glass for the portable device by referring the first and the second correspondence relationships based on the thickness of the sheet glass.

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 a sheet glass by isotropic etching, and then chemically reinforced 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, when the glass sheet is isotropically etched using the resist pattern formed on the main surface of the glass sheet to extract a small glass substrate, the size of the glass substrate extracted is the glass sheet. It has been found that it varies depending on the thickness of the plate. Moreover, it discovered that the dimension of a glass substrate extended with the chemical strengthening which immerses a glass substrate in a high temperature chemical strengthening process liquid. As a result of further investigation, the present inventors have found that the correspondence between the plate thickness of the glass sheet and the dimensions of the glass substrate extracted by isotropic etching, and the chemical strengthening condition and the chemical strengthening condition. While determining the chemical strengthening conditions based on the plate thickness of the sheet glass while referring to the corresponding relationship with the elongation of the dimensions of the glass substrate, the inventors found that the above problems can be solved and completed the present invention. It was.

  In order to solve the above-mentioned problems, a typical configuration of a method for manufacturing a cover glass for a portable device according to the present invention is an isotropic etching of a sheet glass using a resist pattern formed on the main surface of the sheet glass. By performing the shape processing step for processing into a glass substrate in the shape of a cover glass for portable devices, and by bringing the glass substrate into contact with the chemical strengthening treatment liquid, some ions contained in the glass substrate are obtained from the ions. A method of manufacturing a cover glass for a portable device, comprising: a chemical strengthening step for chemically strengthening a glass substrate by ion exchange with ions in a chemical strengthening treatment liquid having a large ion radius, The first correspondence between the thickness of the glass sheet and the dimensions of the glass substrate extracted by etching, the chemical strengthening conditions and the chemical strength in the chemical strengthening process The second correspondence relationship with the elongation of the dimension of the glass substrate when chemical strengthening is performed in advance is grasped in advance, and in the chemical strengthening step, the first correspondence relationship is based on the thickness of the sheet glass. With reference to the second correspondence relationship, the glass substrate is chemically strengthened under a chemical strengthening condition in which the size of the glass substrate after the chemical strengthening step becomes a size 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 plate thickness of the plate glass, the dimension of the glass substrate processed in the shape processing step changes. Therefore, in the above configuration, the dimensional accuracy of the glass substrate is improved by changing the chemical strengthening conditions.

  That is, in the shape processing step, when the plate glass has a different thickness, the dimensions of the glass substrate processed by isotropic etching change. In the chemical strengthening process, the dimensions of the glass substrate vary depending on the chemical strengthening conditions. Therefore, according to the above configuration, the first correspondence relationship between the plate thickness of the glass sheet and the dimension of the glass substrate extracted by isotropic etching, and the second relationship between the chemical strengthening condition and the elongation of the glass substrate dimension. Are previously grasped. The first correspondence relationship is established on the assumption that the resist pattern shape and etching conditions are constant. Thereafter, in the chemical strengthening step, referring to the first correspondence relationship and the second correspondence relationship based on the plate thickness of the sheet glass, the dimension after chemical strengthening is the dimension required for the cover glass for portable devices. The glass substrate is chemically strengthened under such chemical strengthening conditions. In this way, the dimensional error of the glass substrate extracted by isotropic etching caused by the plate thickness of the plate glass can be adjusted by chemical strengthening, so the dimensional accuracy of the glass substrate after chemical strengthening is improved. To do.

  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, in the aluminosilicate glass, Li ions contained in the glass are exchanged with Na ions, and Na ions are exchanged with K ions to be chemically strengthened. 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, by reducing the Li ion concentration as the dimension of the glass substrate after isotropic etching is smaller than the desired dimension, the degree of ion exchange during chemical strengthening is increased, and the glass substrate by chemical strengthening. The elongation of the dimension 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 time for contacting the glass substrate with the chemical strengthening treatment liquid is lengthened, the degree of ion exchange during chemical strengthening can be increased, and the elongation of the glass substrate due to chemical strengthening can be increased. Can do. On the other hand, if the time during which the glass substrate is brought into contact with the chemical strengthening treatment solution is shortened, the degree of ion exchange during chemical strengthening can be reduced, and the elongation of the dimension 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 of the chemical strengthening treatment liquid 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. On the other hand, if the temperature of the chemical strengthening treatment liquid is lowered, the degree of ion exchange during chemical strengthening can be lowered, and the elongation of the dimension 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 this embodiment, when manufacturing the cover glass, paying attention to the dimensions of the glass substrate being changed in the etching process and the chemical strengthening process described later, the dimensions of the glass substrate after the chemical strengthening are desired as a desired product. The purpose is to obtain a high dimensional accuracy that is the target dimension. Hereinafter, a cover glass manufacturing system capable of performing a series of steps including an etching step and a chemical strengthening step will be described.

  FIG. 2 is a functional block diagram of a system for manufacturing a cover glass for portable devices in the present embodiment. The control 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 plate thickness measuring device 150, a strengthening condition determining device 160, a grasping device 170, and a memory 180 that stores a first table and a second table. It has.

  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. In particular, an aluminosilicate glass containing SiO ₂ , Al ₂ O ₃ , Li ₂ O and / or Na ₂ O is preferable. 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 opening by etching, the end face of the outer shape and the inner wall surface of the opening have a very high smoothness on the mirror surface, and the microcrack that always occurs in machining does not occur, and the high strength required for the cover glass Can be obtained. Moreover, even a complicated shape difficult to machine can be easily formed.

  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. When the exposed resist material is developed, a resist pattern is formed in a region other than the region to be etched (remaining region) (negative type).

  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 melted so that the grooves are dug down from both sides, and eventually the grooves on both sides are connected at approximately the center of the plate thickness, thereby forming the outer shape or opening of the glass substrate. In this way, the etching process by the etching processing apparatus 130 is performed.

  The present inventors paid attention to the fact that the dimensions (outside dimensions) of the extracted glass substrate change when the plate glass 120 is different in isotropic etching (see FIG. 3). FIG. 3 is a view showing a cross section of a glass substrate extracted by isotropic etching. Here, the cross-sectional shapes of the glass substrates 100A and 100B when the plate-like glass 120 is isotropically etched by wet etching are shown. In the drawing, resist masks 204a and 204b formed on both main surfaces of the glass substrates 100A and 100B are indicated by hatching. Here, the dimensions (width in the main surface direction) of the resist masks 204a and 204b of the resist pattern formed in the exposure process using one type of photomask are La and Lb (where La = Lb), respectively. Is shown. Further, the thicknesses of the glass substrates 100A and 100B are indicated by Da and Db (where Da <Db), respectively, as shown.

  As shown in FIG. 3A, the end surface of the glass substrate 100A has a protruding portion 106a whose central portion protrudes outward, and from the protruding portion 106a toward both main surfaces, Inclined surfaces 106b and 106c are formed. Note that the boundaries between the inclined surfaces 106b and 106c and the main surface and the protruding portions 106a between the inclined surfaces 106b and 106c preferably 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. Similarly, as shown in FIG. 3B, the projecting portion 108a and the inclined surfaces 108b and 108c are also formed on the end surface of the glass substrate 100B by isotropic etching.

  The external dimensions of the glass substrates 100A and 100B are defined by the distance between the protruding portions 106a and 106a and the distance between the protruding portions 108a and 108a on both end faces, respectively. Here, the external dimensions of the glass substrates 100A and 100B are indicated by Wa and Wb (Wa <Wb), respectively, as shown.

  The reason why the external dimensions of the glass substrate extracted by isotropic etching differ depending on the plate thickness will be described. The reason is that the larger the plate thickness, the longer it takes for the glass substrate to separate from the plate glass, and the etching step ensures that the glass substrate with a large plate thickness is separated from the plate glass. For example, the processing time for the isotropic etching is set.

  For example, when isotropic etching is performed for a set processing time, after the glass substrate 100A having a small plate thickness is separated and the protruding portion is formed, it continues until the glass substrate 100B having a large plate thickness is separated. Continue to be etched. In other words, in the etching process, the smaller the plate thickness, the longer the time from the formation of the protruding portion to the end of etching, and the more the protruding portion and the inclined surface of the end face are etched, resulting in the substrate dimensions being reduced. Get smaller. Note that the plurality of arc shapes indicated by alternate long and short dash lines in FIG. 3A and FIG. 3B schematically show the progress of isotropic etching.

  The first table is stored in the memory 180 as shown in FIG. 2. For example, the correspondence relationship between the plate thickness D of the plate glass and the dimension W of the glass substrate extracted by isotropic etching (hereinafter referred to as the first table). , First correspondence relationship). In addition, although the 1st correspondence which a 1st table shows is explained in full detail in Table 1 of an Example, the dimension of the extracted glass substrate becomes large, so that the plate | board thickness of plate glass becomes large from the said reason. Become. In addition, the above first correspondence relationship is based on the premise that the resist mask shape and etching conditions are constant.

  After etching, resist stripping is performed. For example, as a stripping solution for stripping the resist material from the glass substrates 100A and 100B, 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 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 by 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 | wearing the portable terminal device with the glass substrate 100 shown in FIG. 1, and during use of a portable apparatus, 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, ions on the surface of the glass are exchanged with other ions having a larger ion radius, thereby forming a compressive stress layer on the glass surface. Since this compressive stress layer expands the glass substrate, the substrate size of the glass substrate increases.

  The elongation of the outer dimension of the glass substrate varies depending on the chemical strengthening conditions in the chemical strengthening process. Therefore, a second table is prepared that shows the correspondence relationship (hereinafter referred to as the second correspondence relationship) between the chemical strengthening conditions and the elongation of the outer dimensions of the glass substrate by chemical strengthening (the substrate dimension variation ratio for quantitatively expressing the elongation). do it. The second correspondence relationship indicated by the second table will be described in detail in Tables 2 and 3 of the embodiments.

  The second table is stored in the memory 180 as shown in FIG. 2, and shows a second correspondence between the chemical strengthening condition and the elongation of the outer dimension of the glass substrate due to the chemical strengthening. As chemical strengthening conditions, for example, the concentration of Li ions (ppm) contained in the chemical strengthening treatment liquid, the immersion time (hr) that is the time for contacting the glass substrate with the chemical strengthening treatment liquid, Temperature (° 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, so the degree of chemical strengthening decreases. The Li concentration can be changed by exchanging the chemical strengthening treatment liquid or adding molten salt.

  In chemical strengthening, the longer the immersion time and the higher the temperature of the chemical strengthening treatment liquid, the more the ion exchange proceeds and the larger the external dimension of the glass substrate tends to increase. However, the above-mentioned tendency regarding time and temperature may not monotonously increase the external 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 control system 110 will be described. The memory 180 stores the first table and the second table, and makes the grasping device 170 refer to the contents of the first table and the second table in response to a request from the grasping device 170 shown in FIG. The grasping device 170 grasps the first correspondence between the plate thickness of the glass sheet and the substrate dimensions in the etching process from the first table, and also determines the external dimensions of the glass substrate accompanying the chemical strengthening conditions and the chemical strengthening process. The second correspondence with the elongation is grasped from the second table. Furthermore, the grasping device 170 refers to the first and second correspondences in response to a request from the strengthening condition determining device 160.

  On the other hand, the plate thickness measuring device 150 measures the plate thickness of the sheet glass 120 and refers to the measurement data according to the request of the strengthening condition determining device 160. However, plate thickness measurement data may be acquired in advance from a supplier of the plate glass 120, and in this case, the plate thickness measuring device 150 is not necessary.

  The strengthening condition determination device 160 refers to the first correspondence relationship of the first table and the second correspondence relationship of the second table, for example, based on the measurement data of the plate thickness measured by the plate thickness measurement device 150, and performs chemical strengthening. The chemical strengthening conditions are determined so that the outer dimension of the glass substrate after the process becomes a desired outer dimension, that is, a target dimension required as a product. Note that the target dimensions of the glass substrate may be appropriately stored in the memory 180, for example.

  Specifically, the tempering condition determining device 160 refers to the first table based on the measurement data of the thickness of the sheet glass 120 that is actually used, thereby determining the outer dimensions of the glass substrate 100 after the etching process. To grasp. Next, the strengthening condition determination device 160 grasps the difference between the grasped outer dimension of the glass substrate 100 and the target dimension.

  Subsequently, the strengthening condition determining device 160 refers to the second table and selects and determines the chemical strengthening condition for obtaining the elongation of the outer dimension of the glass substrate for correcting the difference in the chemical strengthening step. And in the chemical strengthening processing tank 140, a glass substrate 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, the concentration of Li ions contained in the chemical strengthening treatment liquid, the chemical strengthening conditions such as the immersion time for bringing the glass substrate into contact with the chemical strengthening treatment liquid, the temperature of the chemical strengthening treatment liquid, and the glass by chemical strengthening The elongation (elongation amount) of the external dimensions of the substrate has a corresponding relationship. For this reason, the strengthening condition determination device 160 changes not only one chemical strengthening condition but also changes two or more chemical strengthening conditions selected from these groups, and adjusts the elongation of the outer dimensions of the glass substrate by chemical strengthening. Thereby, you may make it make the external dimension of the glass substrate after chemical strengthening approach a target 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 manufacturing method of the cover glass for portable devices in the present embodiment as described above, the first correspondence relationship between the plate thickness of the plate glass and the outer dimension of the glass substrate extracted by isotropic etching, and chemical strengthening The chemical strengthening condition is determined based on the plate thickness of the sheet glass with reference to the second correspondence relationship between the chemical strengthening condition in the process and the elongation of the outer dimension of the glass substrate. Therefore, the external dimension error of the glass substrate extracted by isotropic etching caused by the thickness of the sheet glass is adjusted by chemical strengthening, and the dimensional accuracy of the glass substrate after chemical strengthening is improved. it can.

  The above adjustment can be similarly applied to the opening size of the glass substrate. Therefore, the dimensional error of the glass substrate opening extracted by isotropic etching caused by the plate thickness of the glass sheet can be adjusted by chemical strengthening, improving the dimensional accuracy of the glass substrate opening. To do. 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 3 are examples showing experimental results for grasping the correspondence between the plate thickness of the sheet glass and the substrate dimensions after the etching process (substrate dimension variation ratio). This correspondence corresponds to the first table in the above embodiment.

First, the plate | board thickness of plate-like glass was measured and the plate-like glass of three types of plate | board thickness of Example 1-3 was prepared. Glass composition, and 62.5 to 64.5 wt% of SiO _2, and 13 to 15 wt% _Al 2 _{O 3,} and 5-7 wt% of Li ₂ O, 9.5 to 11.5 wt% and Na ₂ O of using glass material containing 5-7 wt% of ZrO _2.

  A resist was applied to both surfaces of each of the above plate-like glasses, and a predetermined pattern was exposed and developed using one type of 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.

  Then, the board | substrate dimension of the glass substrate cut out from each plate glass was measured. 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. The number of measurement sheets is 10 for each of Examples 1 to 3. Table 1 shows the results.

  According to Examples 1 to 3 in Table 1, the first correspondence relationship between the plate thickness of the glass sheet and the substrate dimensions was obtained. Here, the substrate dimension variation ratio is for quantitatively representing the elongation of the substrate dimension due to chemical strengthening. The substrate size variation ratio is a value obtained by dividing the substrate size of each plate thickness by the substrate size of 0.5 (mm) thickness, and is a plate-like glass substrate with a standard plate thickness of 0.5 (mm). The dimensional variation ratio is 1. In addition, the board | substrate dimension of each board thickness is an average value of 10 sheets measured. From the above experimental results, it was confirmed that the first correspondence relationship that the substrate dimension variation ratio increases when the plate glass is thick and the substrate dimension variation ratio decreases when the plate glass is thin.

  Examples 4 to 9 are examples showing experimental results for grasping the second correspondence relationship between the chemical strengthening condition and the substrate dimension (substrate dimension variation ratio). This correspondence corresponds to the second table in the above embodiment.

  In Examples 4 to 6, the dimensions of the glass substrate after the etching step of Example 2 were measured, and the Li concentration of the chemical strengthening treatment liquid was adjusted to 0 (ppm), 900 (ppm), or 1800 (ppm). It is a glass substrate that is chemically strengthened by setting three types. The chemical strengthening treatment liquid is a mixed salt of potassium nitrate and sodium nitrate, temperature 360 (° C.), and immersion time is 3 hours. The 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 measurement method of the substrate dimensions and the number of measurement are the same as in Examples 1-3. The results are shown in Table 2. The substrate dimension variation ratio due to chemical strengthening in the table is the substrate size after chemical strengthening / the substrate size before chemical strengthening. The substrate dimension variation ratio is an average value of 10 sheets measured.

  In Examples 7 to 9, the dimensions of the glass substrate after the etching process of Example 2 were measured, and the temperature of the chemical strengthening treatment liquid for the glass substrate was changed to 3 of 340 (° C.), 360 (° C.), and 380 (° C.). Chemical strengthening by setting the type. The chemical strengthening treatment liquid is a mixed salt of potassium nitrate and sodium nitrate, the Li concentration is 900 (ppm), and the immersion time is 3 hours. The method for measuring the Li concentration of the chemical strengthening treatment liquid is the same as in Examples 4 to 6. After chemical strengthening, predetermined cleaning was performed, and the glass substrate dimensions were measured. The method for measuring the substrate dimensions, the number of sheets to be measured, and the method for calculating the substrate dimension variation ratio by chemical strengthening are the same as in Examples 4-6. The results are shown in Table 3.

  From Example 4 to Example 6 in Table 2, the second correspondence relationship between the chemical strengthening condition (Li concentration) and the substrate dimensions was obtained. It can be seen that when the Li concentration of the chemical strengthening solution is small, the substrate size variation ratio (increase rate of the substrate size) due to chemical strengthening increases, and when the Li concentration is large, the substrate size variation ratio due to chemical strengthening decreases.

  From Example 7 to Example 9 in Table 3, the second correspondence relationship between the chemical strengthening conditions (temperature of the processing solution) and the substrate dimensions was obtained. It can be seen that the substrate size variation ratio due to chemical strengthening increases when the temperature of the chemical strengthening treatment solution is high, and the substrate size variation ratio due to chemical strengthening decreases when the temperature is low.

(Example)
In the examples, the first correspondence relationship between the plate thickness of the plate-like glass and the glass substrate size in Table 1, the Li concentration of the chemical strengthening treatment liquid in Tables 2 and 3, the temperature of the chemical strengthening treatment solution, and the glass substrate Chemical strengthening was performed by referring to the second correspondence relationship with the elongation of the outer dimensions.

  In this example, plate glass having a plate thickness of 0.515 (mm) with respect to a standard plate thickness of 0.5 (mm) was used. The plate thickness of the plate glass was distributed between 0.511 (mm) and 0.519 (mm), and the average value was 0.515 (mm). The glass composition of the sheet glass is the same as in Examples 1 to 3. By applying a negative resist on both sides of the plate glass and using a standard photomask (for standard plate thickness of 0.5 (mm) here), the resist is exposed and developed. A pattern was formed. Next, the resist pattern was cut into a glass substrate by etching, and the remaining resist was removed and washed.

  Here, the plate-like glass moving speed at the time of external processing by etching was set to 1.04 (m / min). The plate glass moving speed is the plate glass moving speed in the transport type etching processing apparatus, and means that the etching processing time becomes longer as the moving speed is lower. Then, with reference to Table 2 and Table 3, it chemically strengthened by Li concentration 1800 (ppm) of the chemical strengthening process liquid, and temperature 340 (degreeC). The immersion time for chemical strengthening is 3 hours. Table 4 shows the dimensions of the glass substrate after chemical strengthening. The dimension of the glass substrate was measured 700 sheets.

(Comparative example)
In the comparative example, a sheet glass having a plate thickness distribution similar to that of the example and a plate thickness of 0.515 (mm) having the same average value was used, and the outer shape was processed under the same etching conditions as in the example. Thereafter, chemical strengthening was performed without referring to the correspondence relationship between the Li concentration and temperature of the chemical strengthening treatment liquid and the elongation of the outer dimensions of the glass substrate. The chemical strengthening conditions are an Li concentration of 900 (ppm), a temperature of 360 (° C.), and an immersion time of 3 hours. Table 4 shows the dimensions of the glass substrate after chemical strengthening. The dimension of the glass substrate was measured 700 sheets.

  From Table 4, with reference to the first correspondence relationship in Table 1, when the thickness of the sheet glass is thicker than the standard, it is grasped that the substrate size after the cutting process becomes large, and the table is used to correct this. 2 and the second correspondence relationship of Table 3, the glass substrate of the example which was implemented under the condition that the elongation was smaller than the standard, specifically, the LI concentration was 1800 (ppm) and the temperature was 340 (° C.). The dimension was 48.004 (mm), which substantially coincided with the target dimension 48 (mm). On the other hand, the glass substrate of the comparative example which performed the chemical strengthening of the standard conditions when the plate | board thickness of plate-like glass was thicker than a standard, without referring the 1st correspondence of Table 1-3, and the 2nd correspondence The dimension was 48.028 (mm), which was shifted by 0.028 (mm) from the target dimension 48 (mm).

  As described above, in the embodiment in which the thickness of the glass sheet to be used is grasped and the chemical strengthening process is performed under the chemical strengthening condition in consideration of the elongation amount of the glass substrate, the dimensional accuracy of the glass substrate may be further improved. It was confirmed.

  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, and either the long side dimension or the opening dimension was measured. The chemical strengthening condition may be determined with reference to the first correspondence relationship with the thickness and the second correspondence relationship between the elongation due to chemical strengthening of the dimension and the chemical strengthening condition. 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 plate thickness / chemical strengthening conditions.

  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, 100B ... Glass substrate, 102 ... Outline part, 104 ... Opening, 106a, 108a ... Projection part, 106b, 106c, 108b, 108c ... Inclined surface, 110 ... Control system, 120 ... Sheet glass, 130 ... Etching Processing device 140 ... Chemical strengthening treatment tank 150 ... Plate thickness measuring device 160 ... Strengthening condition determining device 170 ... Grasping device 180 ... Memory

Claims (4)

A shape processing step for processing a glass substrate in a cover glass shape for a portable device by isotropically etching the plate glass using a resist pattern formed on the main surface of the plate glass;
By bringing the glass substrate into contact with the chemical strengthening treatment liquid, by ion exchange of some ions contained in the glass substrate with ions in the chemical strengthening treatment liquid having an ionic radius larger than the ions. A chemical strengthening step for chemically strengthening a glass substrate;
In the shape processing step, a first correspondence between the thickness of the sheet glass and the dimension of the glass substrate extracted by etching,
In the chemical strengthening step, grasp in advance the second correspondence relationship between the chemical strengthening condition and the elongation of the dimension of the glass substrate when chemical strengthening is performed under the chemical strengthening condition,
In the chemical strengthening step, the size of the glass substrate after the chemical strengthening step is determined to be a cover glass for portable devices by referring to the first correspondence relationship and the second correspondence relationship based on the plate thickness of the plate glass. A method for producing a cover glass for a portable device, wherein the glass substrate is chemically strengthened under chemical strengthening conditions having dimensions required for the above. The glass substrate is an aluminosilicate glass containing Li ions,
The said chemical strengthening condition is the density | concentration of Li ion contained in a chemical strengthening process liquid, The manufacturing method of the cover glass for portable devices of Claim 1 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 Claim 1 or 2 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 1-3 characterized by the above-mentioned.

Images