JP5636022B2 - Glass substrate for cover glass for electronic equipment and method for manufacturing the same - Google Patents

Description

  The present invention relates to a glass substrate for a cover glass for electronic devices and a method for producing the same, and more particularly to a glass substrate for a cover glass for electronic devices that has been chemically strengthened and a method for producing the same.

  In a portable electronic device equipped with an image display panel such as a liquid crystal panel or an organic EL panel such as a mobile phone, a cover glass for a display or a glass for a casing of a portable electronic device is used to protect the image display panel. Cover glass for electronic devices (hereinafter collectively referred to as MCG).

  Such MCG is produced as follows, for example. First, a glass substrate containing a metal oxide is cut into a predetermined shape to produce a small plate-like glass substrate.

Next, the fragmented glass substrate is immersed in the molten salt. This molten salt contains, for example, metal ions K ⁺ having a radius larger than the metal ions Na ⁺ of the metal oxide contained in the glass substrate (FIG. 2 (a)). By immersing the glass substrate in the molten salt, exchange of metal ions is performed in the vicinity of the surface of the glass substrate. Then, many metal ions K ⁺ having a relatively large ion radius are present in the vicinity of the surface of the glass substrate (FIG. 2B). As a result, a layer with improved compressive stress is formed near the surface of the glass substrate as compared to before immersion in the molten salt.

  In this specification, this technique is also referred to as “chemical strengthening” in consideration of the functional aspect of improving compressive stress. In addition, the above process is referred to as a “substitution process” or an “ion exchange process”.

  After this replacement step, the surface of the chemically strengthened glass substrate is washed with water or an aqueous solution. Then, various functional films such as an antireflection film are formed on the surface of the chemically strengthened glass substrate as necessary.

  In this way, the MCG is formed. Patent Documents 1 to 3 are already known as specific prior art documents disclosing this technology.

On the other hand, when washing is performed after the substitution step, a large number of metal ions K ⁺ existing near the surface of the glass substrate are ion-exchanged with hydronium ions having an ion radius smaller than K ⁺ due to ion exchange during chemical strengthening. End up. As a result, a hydrated layer is formed near the surface of the glass substrate by hydronium ions.

  This hydrated layer has a tensile stress, and even if a layer with improved compressive stress is formed by chemical strengthening, the effect will be offset, resulting in a decrease in the strength of MCG. There is a risk.

Therefore, the present applicant has found a technique of removing a portion where K ⁺ is excessively present in the vicinity of the surface of the chemically strengthened glass substrate after the substitution step (see, for example, Patent Document 4). . More specifically, this technique reduces the chance of ion exchange with hydronium ions in the first place by removing the portion where K ⁺ is excessively present and reducing the number of K ⁺ in advance. Thereby, formation of the hydration layer which a tensile stress works can be suppressed, As a result, high intensity | strength can be exhibited in MCG.

JP 2007-99557 A International Publication Number WO2009 / 078406 JP 2009-167086 A JP 2010-168270 A JP-A-8-180402

  On the other hand, when the etching process is performed on the vicinity of the surface of the chemically strengthened glass substrate, the surface of the glass substrate is removed, and accordingly, a new surface that has not been touched by the etching solution or etching gas until now is formed on the glass substrate. It will be formed.

This new surface is in a substantially gel state, for example, and is in a state where ion diffusion is intense in the vicinity of the new surface (hereinafter, this state is also referred to as “active state” and “surface is activated”). It has become. If this state is left as it is, a step of forming various functional films such as an antireflection film is performed while maintaining the above-mentioned state. However, during the process, the state where ion diffusion is intense is maintained, and Na ⁺ may move excessively near the surface of the glass substrate. As a result, the surface of the glass substrate may be burned, which may cause stress relaxation or reduce the strength of the glass substrate.

As a technique for improving the weather resistance in the surface state of a glass substrate, a technique for a glass substrate for a magnetic recording medium is known instead of a technique for MCG (see, for example, Patent Document 5). This technique is to suppress the elution of K ⁺ of the glass substrate for a magnetic recording medium after chemical strengthening from the glass substrate.

This technique will be specifically described with reference to FIG. 6 showing a surface portion of a glass substrate for a magnetic recording medium.
First, in order to chemically strengthen the glass substrate for magnetic recording media, a replacement process of Na ⁺ in the glass substrate and K ⁺ in the molten salt is performed, and then the alkali-free metal treatment is performed by immersing the glass substrate in warm water. (FIG. 6A). In order to fill in the presence of K ⁺ removed by this dealkalizing metal treatment, a large amount of Zn ²⁺ having an ionic radius smaller than K ⁺ is implanted in the vicinity of the surface of the glass substrate (FIG. 6B). By this injection of ^{Zn 2+, Zn 2+} is a barrier layer of ^{K +} elution (so to speak lid), is a technique called.

FIG. 6C shows the relationship between the distance in the thickness direction from the main surface of the glass substrate and the ion concentration. You see, in situations where K ⁺ is removed, Zn ²⁺ is possible substitute for the cover, in the vicinity of the surface it can be seen that Zn ²⁺ is abundant.

However, when K ⁺ is removed by dealkalizing metal treatment and Zn ²⁺ having an ionic radius smaller than Na ⁺ is injected so much, the compressive stress acquired by the chemical strengthening eventually returns to its original state, or chemical strengthening. There is no denying the possibility of deterioration.

  In addition, a static pressure strength test peculiar to MCG, which is one of the uses of the present invention, was carried out on the glass substrate for magnetic recording medium described in Patent Document 5 (details are described in detail in Examples). In such a case, the deterioration may be remarkable.

  Therefore, an object of the present invention is to suppress deterioration of the glass substrate of the cover glass for electronic equipment accompanying activation of the surface of the glass substrate.

This inventor examined the glass substrate of the cover glass for electronic devices which can achieve the above-mentioned object, and its manufacturing method. At that time, the reason why the new surface was activated by removing the portion where K ⁺ excessively exists by etching treatment was examined.

As a result of repeated studies by the present inventors, it has been found that the main factor among the activation factors is a hydroxyl group bonded to Si in the glass substrate (hereinafter referred to as OH group). That is, the present inventors have found that ion diffusion in the glass substrate is excessively caused mainly by the presence of OH groups. Based on this knowledge, the present inventor has conceived a means of suppressing activation of the surface of the glass substrate by making the OH group unable to contribute to ion diffusion.
In the present specification, “electronic device cover glass (ie, MCG)” refers to a glass substrate that is finally attached to an electronic device. The “glass substrate” refers to a glass substrate in a state before becoming an MCG.

Aspects of the present invention based on the above findings are as follows.
The first aspect of the present invention is:
In the vicinity of the surface of the glass substrate containing the metal oxide, a substitution step of substituting the metal ion α of the metal oxide with a metal ion β having an ionic radius larger than the metal ion α;
An implantation step of performing a surface deutilization ion γ implantation treatment on the chemically strengthened layer formed in the vicinity of the surface of the glass substrate by the substitution step;
Have
In the chemical strengthening layer, the ion concentration of the surface depleted ions γ is equal to or less than the ion concentration of the metal ions β in the relationship between the thickness direction distance from the main surface of the glass substrate and the ion concentration. This is a method for producing a glass substrate of a cover glass for electronic equipment.
A second aspect of the present invention is the invention according to the first aspect,
The metal ion α is Na ⁺ , the metal ion β is K ⁺ , and the surface deutilization ion γ is Zn ²⁺ .
A third aspect of the present invention is the invention according to the first or second aspect,
The method further includes a removal step of removing a portion of the chemical strengthening layer located near the surface between the replacement step and the implantation step.
A fourth aspect of the present invention is the invention according to any one of the first to third aspects,
The method further includes an acid cleaning step of performing acid cleaning on the chemical strengthening layer between the replacement step and the implantation step.
The fifth aspect of the present invention is:
A substitution step of substituting the metal ion Na ⁺ of the metal oxide with the metal ion K ⁺ in the vicinity of the surface of the glass substrate containing the metal oxide;
For the chemical strengthening layer formed in the vicinity of the surface of the glass substrate by the replacement step, a removal step of removing a portion located in the vicinity of the surface by etching,
An acid cleaning step for performing acid cleaning on the chemically strengthened layer formed in the vicinity of the surface of the glass substrate by the replacement step;
After the removing step and the acid cleaning step, the chemical strengthening layer has an implantation step of implanting surface deutilized ions Zn ²⁺ ,
In the chemical strengthening layer, the ion concentration of the surface deutilized ions Zn ²⁺ is less than or equal to the ion concentration of the metal ions K ⁺ in the relationship between the distance in the thickness direction from the main surface of the glass substrate and the ion concentration. A method for producing a glass substrate for a cover glass for electronic equipment.
The sixth aspect of the present invention is
The chemically strengthened layer formed in the vicinity of the surface of the glass substrate containing a metal oxide is
A metal ion α of the metal oxide;
A metal ion β having a larger ion radius than the metal ion α, and
A surface deactivating ion γ for deactivating the surface of the glass substrate,
In the chemical strengthening layer, the ion concentration of the surface deutilized ions γ is equal to or less than the ion concentration of the metal ions β in the relationship between the distance in the thickness direction from the main surface of the glass substrate and the ion concentration. It is the glass substrate of the cover glass for electronic devices characterized by these.

  ADVANTAGE OF THE INVENTION According to this invention, deterioration of the glass substrate of the cover glass for electronic devices accompanying the activation of the surface of a glass substrate can be suppressed.

It is a figure which shows the manufacturing method of the glass substrate of the cover glass for electronic devices by this embodiment in order of a process, (a) thru | or (i) is the cross-sectional schematic diagram. It is a schematic sectional drawing of the surface part of a glass substrate which shows the mode of the ion exchange in the substitution process performed in FIG.1 (b). It is a schematic sectional drawing of the surface part of a glass substrate which shows the mode of the removal process currently performed in FIG.1 (c). It is a figure which shows the mode of the bridge | crosslinking performed in the injection | pouring process performed in FIG.1 (d). In this embodiment, a schematic cross-sectional view (FIGS. 5A and 5B) of the surface portion of the glass substrate of the electronic device cover glass, and the distance in the thickness direction from the main surface of the glass substrate of the electronic device cover glass It is the figure (FIG.5 (c)) which described the relationship between ion concentration. In the technique described in Patent Document 5, a schematic cross-sectional view (FIGS. 6A and 6B) of a surface portion of a glass substrate for a magnetic recording medium, and a thickness direction from the main surface of the glass substrate for a magnetic recording medium It is the figure (FIG.6 (c)) which described the relationship between distance of and ion concentration.

[Embodiment 1]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, FIG. 1 is used as a diagram illustrating the basic steps of a method for manufacturing a glass substrate for a cover glass for electronic equipment, and the description will be given in the following order. In addition, the same code | symbol is used for the part common to each figure.
1. Manufacturing method of glass substrate of cover glass for electronic equipment A) Preparation process of glass substrate B) Replacement process for chemical strengthening C) Removal process by etching D) Implantation process of surface depleted ions E) Formation process of resist layer F ) Patterning step for resist layer G) Cutting step by etching H) Step for forming decorative layer I) End face treatment step 2. Explanation about MCG Effects of the Embodiments Modifications are described in Embodiments 2 to 4.

<1. Manufacturing Method of Glass Substrate for Cover Glass for Electronic Equipment>
A) Preparatory process of glass substrate First, the outline of the whole process in this embodiment is described. In the present embodiment, a chemical strengthening layer 2 is formed as a part of the glass substrate 1 near the surface of the glass substrate 1 in FIG. Thereafter, the main surface of the chemically strengthened layer 2 is deactivated, and then the glass substrate 1 is cut into a predetermined outer peripheral shape. The decorative layer 5 is provided so as to cover the chemically strengthened layer 2 (and thus the surface deutilized ion-implanted layer 3) of each cut glass substrate 1.

As the glass material constituting the glass substrate 1 of the present embodiment, any glass material can be used as long as it is a glass material containing an alkali metal oxide capable of ion exchange treatment. If you want to illustrate glass materials,
(1) At least one alkali metal oxide selected from SiO ₂ , Al ₂ O ₃ , Li ₂ O, and Na ₂ O used for the production of the plate-like glass substrate 1 using a downdraw method or the like And, including aluminosilicate glass,
(2) Soda lime glass used for the production of the plate-like glass substrate 1 using the float method,
It is preferable to use a known glass material.

  In addition, when the plate-shaped glass substrate 1 is produced using the down draw method, scratches on the surface of the glass substrate 1 are extremely reduced compared to the float method and the like, and the smoothness is reduced to a nanometer order roughness. stay. For this reason, the mirror polishing process for forming the main surface during the production of the glass substrate 1 can be omitted, and the occurrence of microcracks existing on the main surface can be extremely reduced.

The glass substrate 1 is preferably made of aluminosilicate glass, soda lime glass, borosilicate glass, or the like. Among them, the glass substrate 1 _is preferably formed of a aluminosilicate glass containing at least one selected from the group consisting of _{SiO 2, Al 2 O 3,} Li 2 O and Na ₂ O.

In particular, the aluminosilicate glass preferably contains the following compounds in the following ranges.
SiO _2: 62wt% ~75wt%
_{Al 2 O 3: 5wt% ~15wt} %
Li ₂ O: 0wt% ~8wt%
Na ₂ O: 4 wt% to 16 wt%
ZrO ₂ : 0 wt% to 12 wt%
MgO: 0 wt% to 6 wt%

SiO ₂ is a main component that forms a glass skeleton. The ratio of SiO ₂ is preferably 62 wt% to 75 wt% in view of chemical durability and melting temperature.

Al ₂ O ₃ is contained in order to improve the ion exchange performance on the glass surface. The ratio of Al ₂ O ₃ is preferably 5 wt% to 15 wt% in view of chemical durability and the like.

Li ₂ O is a component that is a source of Li ⁺ that is ion-exchanged with Na ⁺ in the vicinity of the surface of the glass substrate 1. The ratio of Li ₂ O is preferably 0 wt% to 8 wt% in consideration of ion exchange performance and chemical durability.

Similarly, Na ₂ O is a component that is a source of Na ⁺ that is ion-exchanged with K ⁺ in the vicinity of the surface of the glass substrate 1. The ratio of Na ₂ O is preferably 4 wt% to 16 wt% in consideration of mechanical strength and chemical durability.

ZrO ₂ has the effect of increasing the mechanical strength. The ratio of ZrO ₂ is preferably 0 wt% to 12 wt% in consideration of chemical durability and stable production of homogeneous glass.

  Similarly, MgO has the effect of increasing the mechanical strength. The MgO ratio is preferably 0 wt% to 6 wt% in consideration of chemical durability and stable production of homogeneous glass.

B) Substitution process for chemical strengthening In the substitution process for chemical strengthening, as shown in FIG. 1B, a glass substrate 1 containing one or more kinds of alkali metals is melted containing one or more kinds of alkali metals. Contact with salt. Thereby, an ion exchange process is performed. In this replacement step, the glass substrate 1 is usually immersed in the molten salt so that both surfaces of the glass substrate 1 are subjected to ion exchange treatment. Of course, the ion exchange treatment may be performed only on the other side with one side protected. Hereinafter, “main surface” refers to at least part of the outer surface of the glass substrate. Further, “near the surface” means at least a part of the layered region of the glass substrate including the “main surface”.

  Here, the ion exchange process will be described again with reference to FIG. 2 showing the state of ion exchange in the substitution step performed in FIG.

The molten salt contains, for example, a metal ion β (here, K ⁺ ) having a radius larger than that of the metal ion α (here, Na ⁺ ) of the metal oxide contained in the glass substrate 1 (FIG. 2 (a)). By immersing the glass substrate 1 in this molten salt, exchange of metal ions is performed in the vicinity of the surface of the glass substrate 1. Then, many metal ions K ⁺ having a relatively large ion radius exist near the surface of the glass substrate 1 (FIG. 2B).

  That is, in the vicinity of the surface of the glass substrate 1 containing the metal oxide, the metal ion α of the metal oxide is replaced with the metal ion β having an ion radius larger than the metal ion α. As a result, a layer having improved compressive stress is formed near the surface of the glass substrate 1 as compared to before immersion in the molten salt.

  The “chemically strengthened layer 2” in the present embodiment refers to a part of the glass substrate 1 that is chemically strengthened and is located near the surface of the glass substrate 1. At the same time, it contains a compound that is the source of the metal ion α, which is a portion where the metal ion α is replaced by the metal ion β and has improved compressive stress.

Here, the types of metal ions α and β are not particularly limited as long as they have the relationship of the size of the ion radius as described above. However, the metal ion α is preferably derived from a compound originally contained in the glass substrate 1. Specific examples of the metal ion α include alkali metal ions, particularly Li ⁺ and Na ⁺ among them. In the present embodiment, a case where the metal ion α is Na ⁺ will be described.

The metal ion β is preferably not originally contained in the glass substrate 1 or derived from a small amount of compound even if it is contained. This is because when ion exchange is performed, the compressive stress in the chemically strengthened layer 2 is dramatically improved before and after the replacement step. Specific metal ions β include, for example, alkali metal ions, particularly K ⁺ among them. In the present embodiment, the case where the metal ion β is K ⁺ will be described.

The composition of the molten salt, the temperature of the molten salt, and the immersion time can be appropriately selected according to the composition of the glass substrate 1, the thickness of the chemically strengthened layer 2 in which the compressive stress in the glass substrate 1 is improved, and the like. For example, if the composition of the glass substrate 1 is the aluminosilicate glass or soda lime glass described above, the composition of the molten salt, the temperature of the molten salt, and the immersion time are generally selected from the ranges exemplified below. It is preferable to do.
(1) Composition of molten salt: potassium nitrate or a mixed salt of potassium nitrate and sodium nitrate (2) Temperature of molten salt: 320 ° C to 470 ° C
(3) Immersion time: 3 minutes to 600 minutes

  In addition, it is preferable that this substitution process is performed at the temperature below the glass point transfer of the material which comprises the glass substrate 1 using the molten salt of potassium nitrate and / or sodium nitrate. By performing such chemical strengthening at a low temperature, alkali ions on the surface can be exchanged with ions having a large ion radius.

  In addition, after chemically strengthening the glass substrate 1, in order to remove the molten salt and other deposits adhering to the glass substrate 1, it is preferable to wash the glass substrate 1. 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 roll body rotating while flowing the cleaning solution in contact with the glass substrate 1 can be used. The dipping method may be performed in a state where ultrasonic waves are applied to the cleaning liquid.

  Regarding the size of the chemically strengthened layer 2, for example, when a glass substrate 1 having a thickness of 0.5 mm to 1.1 mm is used, the chemically strengthened layer 2 has a thickness from the main surface of the glass substrate 1. It is formed in layers in the range of 30 to 150 μm in the direction.

C) Removal step by etching After the substitution step for chemical strengthening, as shown in FIG. 1 (c), it was a part of the chemically strengthened layer 2 in which ion exchange was performed near the surface of the glass substrate 1 by chemical strengthening. Then, a removal step of removing the portion located on the most surface by etching is performed.

The reason for performing the above removal step is as described in the prior art, but will be described again.
First, after performing the substitution step for chemical strengthening, B) in the chemical strengthening layer 2, in the vicinity of the surface of the glass substrate 1 (for example, the region from the outermost layer to a depth of several μm) Due to the strengthening, a layer having a very high ion concentration of K ⁺ is formed.

When the glass substrate 1 in a state in which a layer having a very high ion concentration of K ⁺ exists in this way is washed with water or an aqueous solution, K ⁺ put into the chemical strengthening layer 2 by ion exchange at the time of chemical strengthening, It is ion-exchanged with hydronium ions (H ₃ O ⁺ ) having an ionic radius smaller than K ⁺ . Therefore, the portion closest to the surface becomes a hydrated layer.
As a result, in the vicinity of the surface of the chemically strengthened layer 2 of the glass substrate 1, a hydrated layer on which tensile stress acts is formed by cleaning.

  In particular, the tendency to form this hydrated layer becomes remarkable when an acidic solution is used as the cleaning liquid. Moreover, since the glass substrate 1 shape | molded by the down draw method shape | molds by the press method, and ion exchange advances rapidly compared with the glass substrate 1 obtained by grinding | polishing after that, this tendency becomes remarkable.

Therefore, as shown in FIG. 3, in the vicinity of the surface of the chemically strengthened glass substrate 1, a portion where K ⁺ is excessively present (hatched portion) is removed by etching. That is, by removing the portion where K ⁺ is excessively present and reducing the number of K ⁺ in advance, the opportunity for ion exchange with hydronium ions is reduced in the first place. Thereby, formation of the hydration layer which a tensile stress works can be suppressed, As a result, high intensity | strength can be exhibited in MCG.

  In addition, as a method for removing a part of the chemical strengthening layer 2, etching, polishing, or the like can be given. However, in the case where the glass substrate 1 is directly formed into a sheet shape from the molten glass, it is preferable to select etching so as not to damage the main surface.

A treatment liquid used for removing a portion where K ⁺ is excessively present by etching is at least one selected from the group consisting of hydrofluoric acid, hexafluorosilicic acid (H ₂ SiF ₆ ), and buffered hydrofluoric acid. It is preferable that the solution contains one.

  In this case, the etching temperature is in the range of 20 ° C to 60 ° C, more preferably 30 ° C to 50 ° C. The etching time is preferably 3 minutes to 60 minutes. In addition, as a processing mode at the time of etching, a mode in which the etching solution is circulated by a pump while the glass substrate 1 is immersed in the etching solution may be used, and the glass substrate 1 is moved up and down while the glass substrate 1 is immersed in the etching solution. Alternatively, the glass substrate 1 may be brought into contact with the etching solution in a shower shape.

After removing the portion where K ⁺ is excessively present by etching, deposits may be adhered to the surface of the glass substrate 1, and in order to remove such deposits, the glass is applied with ultrasonic waves applied. The substrate 1 may be cleaned. Examples of the cleaning liquid at this time include aqueous solutions such as water, sulfuric acid, hydrochloric acid, and nitric acid, and a commercially available cleaning agent (neutral detergent, surfactant, alkaline cleaner, etc.) may be used in combination.

The glass substrate 1 obtained in this way has a chemically strengthened layer 2 that has been chemically strengthened to improve the compressive stress. And the K ^<+> density | concentration in the surface vicinity of the chemical strengthening layer 2 is 5000 ppm or less. That is, the glass substrate 1 has a portion near the surface of the chemically strengthened layer 2 having a K ⁺ concentration exceeding 5000 ppm.

It can be determined by the following method that the K ⁺ concentration in the vicinity of the surface of the chemically strengthened layer 2 is 5000 ppm or less. For example, a wavelength dispersive X-ray analyzer (WDX) that irradiates a sample with an electron beam, selects X-rays having an arbitrary set wavelength from various signals excited from the irradiated site, and measures them with a detector. ), Or by irradiating the sample with an electron beam, and amplifying all the various signals excited from the irradiated part with a semiconductor detector and distributing the signals according to energy, and measuring with an energy dispersive X-ray analyzer (EDX) . Other specific measurement methods include secondary ion mass spectrometry (SIMS) and ion chromatography (IC). For example, a substance (Zn ⁺ , K) obtained by dissolving the glass substrate 1 in an acid to form an aqueous solution, and then diffusing the aqueous solution on the surface using an IC or an inductively coupled plasma emission spectrometer (ICP-AES). ⁺ Etc.) may be analyzed. By doing so, it can be confirmed that the K ⁺ concentration in the vicinity of the surface of the chemically strengthened layer 2 is 5000 ppm or less.

D) Surface depletion ion implantation step After the portion where K ⁺ is excessively present is removed by etching, in this embodiment, the main surface of the glass substrate 1 (that is, the main surface of the chemical strengthening layer 2) is deactivated. Therefore, an implantation process is performed for injecting the surface depleted ions γ into the chemically strengthened layer 2. One of the main features of this embodiment is this implantation step. Details will be described below.

  First, when etching is performed on the vicinity of the surface of the chemically strengthened glass substrate 1, the vicinity of the surface of the glass substrate 1 (that is, the portion near the surface of the chemically strengthened layer 2) is removed. A new surface that has not been exposed to the etching solution or the etching gas is formed on the glass substrate 1.

  This new surface is in a substantially gel state, for example, and is in an active state where ion diffusion is intense in the vicinity of the new surface. This active state may cause burns on the surface of the glass substrate 1, which may cause stress relaxation, or may reduce the strength of the glass substrate 1.

  Therefore, the present inventor has obtained the knowledge that the main factor in the activation of the surface of the chemical strengthening layer 2 is an OH group bonded to Si in the glass substrate 1. That is, the present inventors have found that ion diffusion in the glass substrate 1 is caused excessively mainly due to the presence of OH groups.

Based on the knowledge, in the implantation step, the chemical strengthening layer 2 is subjected to a surface depletion ion γ (for example, Zn ²⁺ ) implantation treatment. At that time, in the chemical strengthening layer 2, in the relationship between the distance in the thickness direction from the main surface of the glass substrate 1 and the ion concentration (FIG. 5C), the ion concentration of the surface deutilized ions γ is set as follows. , The ion concentration of the metal ion β is set below.

  As an example of this specific method, C) This step can be carried out by immersing the glass substrate 1 after the removal step by etching in an aqueous solution having surface deutilized ions γ.

  By performing the immersion described above, surface deutilized ions γ are implanted near the surface of the chemical strengthening layer 2. Then, as shown in FIG. 1 (d), the “surface deutilized ion implantation layer 3” is formed as a part of the chemical strengthening layer 2 in the glass substrate 1.

  In addition, the “surface deutilized ion implantation layer 3” in the present embodiment is a part of the chemical strengthening layer 2 in the glass substrate 1 and the surface deutilized ions located in the vicinity of the surface of the glass substrate 1 are Refers to the injected part. At the same time, it refers to the portion where the OH groups present in the vicinity of the surface of the chemically strengthened layer 2 are deactivated.

Here, the deactivation mechanism of the OH group existing in the vicinity of the surface of the chemically strengthened layer 2 will be described with reference to FIG.
First, before the implantation step, when the surface of the chemical strengthening layer 2 is activated, as shown in FIG. 4A, an OH group is bonded to Si in the glass substrate 1. Therefore, as shown in FIG. 4B, the implantation step crosslinks the OH groups separated from each other with the surface deutilized ions γ interposed therebetween, thereby eliminating the state of the OH groups. In the present embodiment, changing the OH group in this way is also referred to as “deactivation”.

  As the surface deutilization ion γ, any ion can be used basically as long as it can crosslink OH groups. However, ions that are not originally contained in the glass substrate 1 are preferable. This is because when the types of ions originally contained in the glass substrate 1 are implanted, the active state of the surface may be suppressed to some extent by the ions originally contained, but ions that are not originally contained are used. This is because, in some cases, a more remarkable surface deactivation effect can be expected.

  Further, as described later, the dealkalizing metal treatment as in Patent Document 5 is not performed in this embodiment. Therefore, the process for removing the metal ions α and β from the glass substrate 1 is not performed, and the metal ions α and β are removed and no space is generated. As a result, surface deutilized ions γ must be implanted where there is no such space.

  In order to perform this implantation promptly, it is preferable to make the ion radius of the surface deutilized ions γ as small as possible. Specifically, it is preferably smaller than the metal ion β, and more preferably smaller than the metal ion α.

  However, it is necessary to prevent the surface depletion ions γ from being excessively injected into the chemical strengthening layer 2 because the surface deutilization ions γ are too small and the surface deactivation ions γ are easily implanted. Specifically, in the relationship between the distance in the thickness direction from the main surface of the glass substrate 1 and the ion concentration (Fig. 5 (c)) under the condition of the surface deutilized ion γ aqueous solution described later, the surface deutilized ions. It is preferable that the surface deutilization ions γ have an ion radius having a magnitude such that the γ ion concentration is equal to or lower than the ion concentration of the metal ions β.

If an example is given about this surface deutilization ion (gamma), Zn2 ⁺ will be mentioned. The compound which is the source of ^{Zn 2+,} include zinc nitrate hexahydrate _{(Zn (NO 3) 2 ·} 6H 2 O) is. In this embodiment, the case where the surface deutilized ions γ are Zn ²⁺ will be described.

The glass substrate 1 is immersed in a zinc nitrate hexahydrate aqueous solution in which the zinc nitrate hexahydrate is dissolved in water. The concentration of the aqueous solution, the immersion temperature, and the immersion time may be changed as needed depending on the composition of the glass substrate 1, the type of metal ions β used in the substitution step, the type of surface depleted ions γ, and the like. However, if an example is given for the case of using zinc nitrate hexahydrate, the following conditions may be mentioned.
Concentration of aqueous solution: 0.3 wt% to 10 wt%
Immersion temperature: 52.5 ° C to 54.9 ° C
Immersion time: 1 minute to 1 hour

  As described above, it is possible to make the OH group unable to contribute to ion diffusion by performing the step of implanting D) surface depleted ions. Thereby, activation of the surface of the glass substrate 1 can be suppressed.

Hereinafter, it will be described that the technique of the present embodiment is completely different from the technique (Patent Document 5) for the glass substrate 1 for a magnetic recording medium, including the reason for the existence of the D) surface deutilization ion implantation step. In this description, FIGS. 5 and 6 are used.
FIG. 5 is a schematic cross-sectional view (FIGS. 5A and 5B) of the surface portion of the glass substrate 1 for MCG in the present embodiment, and the distance in the thickness direction from the main surface of the glass substrate for MCG. It is the figure (FIG.5 (c)) which described the relationship with ion concentration.
6 is a schematic cross-sectional view (FIGS. 6A and 6B) of a surface portion of a glass substrate 1 for a magnetic recording medium in the technique of Patent Document 5, and a main surface of the glass substrate for a magnetic recording medium. It is the figure (FIG.6 (c)) which described the relationship between the distance of a thickness direction, and ion concentration.

As described above, in Patent Document 5, after performing the replacement step of Na ⁺ in the glass substrate 1 and K ⁺ in the molten salt to chemically strengthen the glass substrate 1 for magnetic recording medium, The alkali-free metal treatment is performed by immersing the glass substrate 1 in warm water (FIG. 6A). In order to fill in the presence of K ⁺ removed by this dealkalizing metal treatment, a large amount of Zn ²⁺ having an ionic radius smaller than K ⁺ is implanted near the surface of the glass substrate 1 (FIG. 6B). By this injection of ^{Zn 2+, Zn 2+} is in the barrier layer of the ^{K +} elution (so to speak lid). As evidence, as shown in FIG. 6 (c), Zn ²⁺ is the main factor of chemical strengthening in the vicinity of the surface so that Zn ²⁺ can replace the lid in the situation where K ⁺ is removed. A large amount exists compared to K ⁺ .

On the other hand, in this embodiment, the dealkalizing metal treatment as described in Patent Document 5 is not performed. In the first place, MCG, which is one of the uses of the present invention, does not require alkali elution resistance as required for magnetic recording media, and it is necessary to perform dealkalizing metal treatment as described in Patent Document 5. Absent.
In any case, in this embodiment, D) surface deutilization ion implantation step is performed without performing dealkalizing metal treatment.

In this embodiment, C) a removal process by etching is performed. This is completely different from the removal of only alkali metal such as dealkalization metal treatment described in Patent Document 5. In other words, in the present embodiment and BR> A, as shown in FIGS. 5A and 5B, a part of the chemical strengthening layer 2 located near the surface (that is, K ⁺ is excessively present). Part to be removed). That is, a part (shaded portion) of the glass substrate 1 itself is removed.

In this embodiment, after performing the removal step by C) etching in this way, D) the step of implanting surface deutilized ions is performed. Then, as shown in FIG. 6C, the ion concentration of Zn ²⁺ is equal to or lower than the ion concentration of K ⁺ even in the vicinity of the surface of the chemical strengthening layer 2.
On the other hand, in Patent Document 5, the ion concentration of Zn ²⁺ is very high in the vicinity of the surface of the chemically strengthened layer 2 as compared with the ion concentration of K ⁺ .
The difference between this embodiment and the technique described in Patent Document 5 in this respect will be described below.

In Patent Document 5, since dealkalizing metal treatment is performed, K ⁺ and Na ⁺ are desorbed near the surface of the chemically strengthened layer 2. As a result, an empty space is formed in the vicinity of the surface of the chemically strengthened layer 2 where K ⁺ and Na ⁺ existed (FIG. 6A).

Then, Zn ^<2+> is inject ^| poured with respect to the glass substrate 1 for magnetic recording media by immersing the glass substrate 1 for magnetic recording media in the zinc nitrate aqueous solution. Here, Zn ²⁺ is mainly injected into the vacant space (FIG. 6B).
As a result, a glass substrate 1 for a magnetic recording medium having a relationship as shown in the graph of FIG.

  On the other hand, in this embodiment, since the dealkalizing metal treatment is not performed, the empty space as described above is not formed. The same applies to the removal process by C) etching (FIGS. 5A and 5B). Further, as shown in FIG. 5C, even if the shaded portion is removed in the removal step by C) etching, many metal ions α and β are already present in the vicinity of the surface of the chemically strengthened layer 2. .

Therefore, even if the glass substrate 1 is immersed in the zinc nitrate hexahydrate aqueous solution, no empty space is formed in the glass substrate 1, so that only a small amount of Zn ^{2+ with} respect to K ⁺ is chemically enhanced layer 2. Can not be injected into.

Therefore, in this embodiment, this feature is used to maintain the compressive stress obtained by chemical strengthening. In other words, a technique in which only a small amount of Zn ²⁺ is intentionally injected into the chemical strengthening layer 2 is used so as not to cancel the work of improving the compressive stress by K ⁺ .
As a result, a glass substrate 1 having a relationship as shown in the graph of FIG.

Comparing FIG. 5C and FIG. 6C, it can be seen that the Zn ²⁺ ion concentration in the vicinity of the surface of the chemically strengthened layer 2 is equal to or lower than the K ⁺ ion concentration. By having such a relationship, Zn ²⁺ can be kept at an ion concentration substantially equal to or less than K ⁺ which is a main factor of chemical strengthening in the vicinity of the surface. As a result, the compressive stress acquired by chemical strengthening can be maintained.

  In the present embodiment, “dealkali metal treatment is not performed” means that “in the relationship between the distance in the thickness direction from the main surface of the glass substrate 1 and the ion concentration, It is also clear from the fact that the concentration is made equal to or lower than the ion concentration of the metal ion β. Furthermore, even if dealkalizing metal treatment is performed, if the treatment is performed to such an extent that the ion concentration of the surface deutilized ions γ is equal to or lower than the ion concentration of the metal ions β, the present invention The idea can be applied.

E) Resist layer forming step A dehydration baking process is performed on the glass substrate 1 into which the surface depleted ions γ have been implanted. Then, as shown in FIG.1 (e), the photosensitive resist liquid is apply | coated so that the main surface of the glass substrate 1 may be covered. In the present embodiment, the case of applying to only one surface will be described, but it may be applied to a plurality of surfaces.

  In the present embodiment, a positive resist is used as the photosensitive resist solution. In addition, a well-known thing may be used for the positive resist in this embodiment. As an example, a positive resist material includes azide, diazo, and quinonediazo.

  As a coating method, in this embodiment, a spin coating method is used in which the photosensitive resist solution is dropped onto the main surface of the glass substrate 1 and then the glass substrate 1 is rotated at a predetermined rotational speed. Next, the glass substrate 1 on which the photosensitive resist solution is spin-coated on the main surface is baked at a predetermined temperature and time on a hot plate. Then, for example, it is transferred onto a cooling plate kept at room temperature, cooled, and dried to form a photosensitive resist layer 4. Hereinafter, the photosensitive resist layer 4 is also simply referred to as the resist layer 4.

F) Patterning step for resist layer a) Exposure step After the coating step, a photomask 6 was provided to transfer a predetermined pattern of the photomask 6 to the resist layer 4 as shown in FIG. The resist layer 4 is exposed using an exposure apparatus. In the present embodiment, as described above, the resist layer 4 in the present embodiment is a positive resist. Therefore, the exposed resist layer 4 (exposed portion 4a) becomes a dissolved portion in the development step described later. On the contrary, the resist layer 4 (non-exposed part 4b) of the part not exposed becomes a non-dissolved part.

  In the present embodiment, a portion of the glass substrate 1 corresponding to the exposed portion 4a is removed by wet etching (a cutting step by G described later). This removal is used to cut the glass substrate 1 to produce a plurality of glass substrates 1, drilling using etching or processing to a predetermined outer peripheral shape for each of the plurality of glass substrates 1. Also used for.

  The photomask 6 used at this time may be a known one. For example, it is composed of a transparent substrate such as quartz glass, soda glass, and a plastic film, and a masking thin film for patterning such as a chromium film or an emulsion film.

  Note that pre-exposure baking and / or post-exposure baking may be performed as necessary.

b) Development Step i) Development After exposure to a predetermined shape, the resist layer 4 made of a positive resist is developed with a predetermined developer. As a result, the exposed portion 4a (dissolved portion) exposed in the resist layer 4 is removed, and a resist pattern 4 ′ that is a pattern corresponding to the pattern of the photomask 6 and has unevenness is formed. At this time, a known developer may be used according to the type of resist.

ii) Rinsing and drying Immediately after stopping the dropping of the developer, the rinse agent is dropped and supplied from above the glass substrate 1 while rotating the glass substrate 1 in order to wash away the developer. Then, a drying process is performed with respect to the glass substrate 1 which performed said rinse process. At this time, as the rinsing agent, it is preferable to use a substance having a low surface free energy such as a fluorine-based compound in order to prevent the resist pattern 4 ′ from falling.

  The resist layer 4 exposed in this way is developed, the exposed portion 4a is removed, and a resist pattern 4 'having convex portions and concave portions corresponding to the pattern of the photomask 6 is created. In addition, you may perform a baking process with respect to the glass substrate 1 in which the resist pattern 4 'was formed as needed.

  Thus, a resist pattern 4 ′ having a predetermined uneven shape is formed, and the glass substrate 1 on which the resist pattern 4 ′ is formed on the main surface is obtained.

  Note that baking may be performed as necessary during or after the development step.

G) Cutting step by etching Subsequently, wet etching using hydrofluoric acid is performed on the glass substrate 1. Thus, as shown in FIG. 1G, the glass substrate 1 is cut corresponding to the resist pattern 4 ′. At this time, a plurality of glass substrates 1 are taken out from one glass substrate 1, and at the same time, holes are made in the glass substrate 1 or processed into a predetermined outer peripheral shape.
As a result, the glass substrate 1 after the chemical strengthening and the implantation of the surface depleted ions γ and the resist pattern 4 ′ remaining on the outermost surface is produced.

  Etching in this step is usually performed by immersing the glass substrate 1 in an etching solution. The etching solution is not particularly limited as long as it contains at least hydrofluoric acid, but other acids such as hydrochloric acid and various additives such as a surfactant may be added as necessary.

  Thereafter, the remaining resist pattern 4 'is removed by a stripping solution composed of a mixed solution of sulfuric acid and hydrogen peroxide solution, and the resist pattern 4' is completely stripped. Next, the glass substrate 1 is dried by the same method as the above drying process.

  Specifically, the resist pattern 4 ′ is peeled off by immersing the glass substrate 1 in the stripping solution for a predetermined time, and then washing off the stripping solution with a rinse agent. As the rinse agent, a known rinse agent may be used, and isopropyl alcohol or pure water may be used.

  The stripping solution used here may be appropriately selected according to the type of resist constituting the resist layer 4 and may be any compound that can be stripped and removed by swelling and dissolving or chemically decomposing the resist.

H) Decoration layer forming step After the glass substrate 1 is cut into small pieces by the above G) etching cutting step, as shown in FIG. 1 (h), at least one surface of the ion-exchanged plate glass The decoration layer formation process which forms the one or more decoration layers 5 is implemented.

  As a film forming method for the decorative layer 5, a known film forming method can be appropriately used according to the material constituting the decorative layer 5, the film thickness, and the like. For example, various printing methods such as screen printing, dipping method, spraying, etc. Known liquid phase film forming methods such as a coating method, a sol-gel coating method, and a plating method, and known vapor phase film forming methods such as a vacuum deposition method, a sputtering method, and a CVD (Chemical Vapor Deposition) method can be used.

In addition, as the decoration layer 5 in this embodiment, what is well-known as a decoration layer may be used. For example, decorative printing (epoxy, polyester, urethane, etc.), AR coating, ITO coating, antifouling coating, decorative film, anti-scattering film and the like can be mentioned.
In this embodiment, high strength can be maintained in the glass substrate 1 even after the step of forming the decorative layer 5.

I) End surface treatment process Then, as shown in FIG.1 (i), G) At least one part of the cut surface formed through the cutting process by an etching is grind | polished. Here, the cut surface means an end surface made of a curved surface having a convex shape formed by wet etching. By carrying out this end face processing step, the end face can be flattened by the polishing process.

  After passing through the above steps, the glass substrate 1 is cleaned as necessary. Thus, the glass substrate 1 of the cover glass (MCG) for electronic devices in this embodiment is completed.

<2. Explanation about MCG>
An example of the glass substrate 1 manufactured using the above method will be described.
The glass substrate 1 manufactured in the present embodiment has the following configuration. That is, the chemical strengthening layer 2 formed in the vicinity of the surface of the glass substrate 1 containing a metal oxide includes a metal ion α of the metal oxide, a metal ion β having a larger ion radius than the metal ion α, and the above It contains the surface deactivating ions γ for deactivating the surface of the metal oxide-containing glass substrate 1. In the chemical strengthening layer 2, the ion concentration of the surface depleted ions γ is the ion concentration of the metal ions β in the relationship between the thickness direction distance from the main surface of the glass substrate 1 and the ion concentration. It is as follows.

By having the configuration described above in relation to the thickness direction of the distance and the ion concentration in the main surface of the glass substrate 1, Zn ²⁺ in the vicinity of the surface, and K ⁺ that is a main cause of chemical strengthening The ion concentration can be kept at almost the same or lower. As a result, the compressive stress acquired by chemical strengthening can be maintained.

  In addition, the glass substrate 1 produced by this embodiment can be made into arbitrary shapes according to a use. For example, a glass substrate manufactured according to the present invention can be used as a portable electronic device including at least an image display panel and an MCG provided on the image display surface side of the image display panel, particularly as an MCG for a mobile phone. preferable. The glass substrate according to the present invention can also be used as a casing of a portable electronic device. Portable electronic devices, particularly mobile phones, are often required to have various design characteristics in addition to the main surface portion of the MCG being often exposed to mechanical shocks from the aspect of use. However, the glass substrate in this embodiment can easily meet both needs as described above.

<3. Advantages of the embodiment>
In the glass substrate of the cover glass for electronic devices mentioned here, and its manufacturing method described so far, there exist the following effects.
That is, OH groups bonded to Si in the glass substrate 1 are implanted in the vicinity of the surface of the chemically strengthened layer 2 by injecting surface deutilized ions γ into the vicinity of the surface of the chemically strengthened layer 2 in the active state. Can be deactivated.

As a result, the ion diffusion can be returned from the intense state to the normal state, and the fear that Na ⁺ moves excessively near the surface of the glass substrate 1 can be eliminated. Thereby, it is possible to suppress the occurrence of burns on the surface of the glass substrate 1, and thus it is possible to suppress the occurrence of stress relaxation.

  As a result, the deterioration of the glass substrate 1 of the cover glass for electronic equipment accompanying the activation of the surface of the glass substrate 1 can be suppressed. As a result, it is possible to maintain the strength and scratch resistance of the glass substrate 1 of the cover glass for electronic devices, and consequently the cover glass for electronic devices (MCG), at a high level.

[Embodiment 2]
In the second embodiment, the case where the removal step by C) etching is omitted will be described.
As described above, when the removal step by C) etching is performed, a new surface is formed on the main surface of the glass substrate 1, and the vicinity of the surface becomes active. However, the idea of the present invention can also be applied to the case where the removal step by C) etching is not performed. Furthermore, if the main surface of the glass substrate 1 is in an active state even a little, it can be applied to all cases where D) surface depletion ion implantation step is performed in order to deactivate the active state.

[Embodiment 3]
In the third embodiment, the step of removing by C) is omitted as in the case of the second embodiment, and then, between the step of B) the substitution step for chemical strengthening and the step of D) the surface depletion ion implantation step. The case where acid cleaning is performed on the chemically strengthened layer 2 will be described.

  For this acid cleaning step, the cleaning method described in the removing step by C) etching can be used. That is, an acidic aqueous solution such as sulfuric acid, hydrochloric acid, or nitric acid is used as the cleaning liquid. At this time, the glass substrate 1 may be cleaned in a state where an ultrasonic wave is applied.

[Embodiment 4]
The technical scope of the present invention is not limited to the above-described embodiment, and various modifications and improvements are added within the scope of deriving specific effects obtained by the constituent elements of the invention and combinations thereof. Including.
In the present embodiment, modifications other than those described above are listed.

  In the present embodiment, the glass substrate may be a single glass substrate, or a plurality of glass substrates 1 may be laminated in advance and processed as a single glass substrate. .

  In this embodiment, a positive resist is used, but a negative resist may be used. Specific negative resist materials include photopolymerizable ones such as unsaturated polyester, acrylate, nylon, En addition reaction, and cationic polymerization, metal ion dichromate, and photodimerized light. Those in which cross-linking occurs can be used.

  Moreover, the resist in this embodiment may be other than a resist solution, and a film-like resist may be used.

  In addition, the resist in this embodiment may be any resist that has reactivity when exposed by irradiation with an energy beam. That is, in addition to performing exposure using an exposure apparatus, direct drawing using an energy beam may be performed. Specifically, it may be a resist that needs to be developed with a developer, and may be a resist having sensitivity to ultraviolet rays, X-rays, electron beams, ion beams, proton beams, and the like.

  Further, although the resist is used in the first embodiment, G) means other than the resist may be used as long as a film that can withstand the cutting process by etching can be formed on the glass substrate 1.

  In addition, although wet etching is performed in the etching in this embodiment, a part or all of the etching may be dry etching. Further, an etching method may be selected according to the processing accuracy at the time of etching.

  In the present embodiment, etching is used for processing for taking out a plurality of glass substrates 1 from one glass substrate 1, drilling, and outer shape processing. However, machining may be performed according to circumstances.

  Further, the idea of this embodiment is that at least B) a replacement step for chemical strengthening → D) a step of implanting surface depleted ions may be provided before and after these steps. Applicable. For example, E) a resist layer forming step to G) a cutting step by etching may be performed before the above step. That is, chemical strengthening may be performed on the glass substrate that has been fragmented. Further, B) Substitution process for chemical strengthening → D) Even if another process is included during the process of implanting surface depleted ions, the main surface becomes active. If a good glass substrate 1 can be produced by deactivating the main surface, another step may be further provided.

Example 1
A) Preparation of glass substrate First, SiO ₂ is 62.2 wt%, Al ₂ O ₃ is 13.0 wt%, Li ₂ O is 0.95 wt%, Na ₂ O is 10.7 wt%, and MgO is 5.1 wt%. , Aluminosilicate glass containing 3.9 wt% of ZrO ₂ was molded into a plate-like glass substrate 1 (sheet-like glass) having a long side of 80 mm, a short side of 45 mm, and a plate thickness of 0.5 mm by the downdraw method (FIG. 1 ( a)).

B) Substitution process for chemical strengthening Next, this glass substrate 1 was immersed in a treatment bath of a mixed salt of potassium nitrate (KNO ₃ ) 60 wt% and sodium nitrate (NaNO ₃ ) 40 wt% maintained at 360 ° C. for 6 hours. And chemically strengthened (FIG. 1B, FIG. 2). Subsequently, in order to remove deposits, such as molten salt adhering to this glass substrate 1, it wash | cleaned with water.

C) Removal step by etching Next, the glass substrate 1 is immersed in a 3 wt% H ₂ SiF ₆ aqueous solution kept at 35 ° C., and the glass substrate 1 is vertically rocked to perform etching for 10 minutes. The main surface was etched by about 1 μm (FIGS. 1C, 3 and 5A. The two-dot chain line in FIG. 1C and the hatched portion in FIGS. 3 and 5A were removed). Thereafter, this glass substrate 1 was immersed in a 15 wt% H ₂ SO ₄ aqueous solution kept at 40 ° C. and washed for 5 minutes while applying an ultrasonic wave of 40 kHz.

D) Surface depletion ion implantation step Next, the glass substrate 1 is placed in a 0.3 wt% zinc nitrate hexahydrate (Zn (NO ₃ ) ₂ .6H ₂ O) aqueous solution kept at 52.5 ° C. for 1 hour. It was immersed (FIG. 1 (d), FIG. 4, FIG. 5 (b)). Thereafter, the glass substrate 1 was taken out from the zinc nitrate hexahydrate aqueous solution, washed in a normal temperature running water shower, and dried.
As described above, a sample for evaluation of this example was produced. Moreover, in order to evaluate each with respect to a some sample, the some sample was produced with said method.

  In the examples and comparative examples in this specification, E) is omitted in the resist layer forming step to I) the end face processing step.

(Example 2)
In Example 2, a sample was prepared in the same manner as in Example 1 except for the following points.
Concentration of aqueous solution: 3wt%
Immersion temperature: 54.9 ° C

Example 3
In Example 3, a sample was prepared in the same manner as in Example 1 except for the following points.
Concentration of aqueous solution: 10 wt%
Immersion temperature: 53.0 ° C

(Comparative Example 1)
In Comparative Example 1, D) the step of implanting surface depleted ions was not performed. In addition, the following points (evaluation methods) were also changed from the past. Other than that, a sample was prepared in the same manner as in Example 1.

(Evaluation method)
The static pressure strength test peculiar to MCG was performed on the samples prepared in the above-described examples and comparative examples.
In this static pressure strength test, the MCG is set on a support base that abuts at the outer peripheral edge 3 mm on the main surface of the MCG, and applied to the center of the MCG from the opposite main surface side that abuts the support base. A static pressure strength test was conducted by pressing with a pressure member. The pressurizing member was made of a stainless alloy having a tip of φ10 mm. The pressing speed was 10 mm / min.

  Conventional bending tests for glass for displays and tests using an annular line load such as a magnetic recording medium are based on the premise that the processed glass ends are subjected to maximum stress. This is due to the fact that the glass and magnetic recording media for conventional displays mainly hold the glass substrate itself at the glass edge. That is, the strength test is performed in consideration of an actual usage mode.

  However, the MCG, which is an application of the glass substrate 1 of the present embodiment, is also used for a portable electronic device such as a cellular phone. In particular, if the portable electronic device is of a touch panel type, high strength is required at the central portion of the glass substrate 1. Therefore, with the conventional evaluation method, there is a possibility that the function as the MCG cannot be properly evaluated. That is, with the conventional evaluation method, the strength of the glass edge may be evaluated as the strength of the entire glass substrate, although the strength of the central portion is required. As a result, although it is a glass substrate that does not actually have sufficient strength in the central portion, it may be evaluated as an appropriate glass substrate as MCG.

  In addition, when processing such as cutting glass is performed, fine defects (roughness, microcracks, chipping, and the like) on the outer periphery of the glass are likely to become a starting point for fracture during a conventional static pressure strength test. Therefore, it is difficult to obtain an accurate strength, and it may be difficult to perform an evaluation reflecting the actual use of MCG.

  Therefore, when the evaluation method of the present embodiment is used, it is possible to perform a center concentrated load strength test specialized for the central portion of the glass substrate 1. In this case, the stress is concentrated immediately below the press and the stress at the outer peripheral portion is relatively very small. For this reason, defects on the outer periphery of the glass caused by glass cutting or the like are unlikely to become a starting point of destruction, and the strength of the glass itself and the glass surface is strongly reflected. As a result, evaluation reflecting the actual use of MCG can be performed.

  In the above-described evaluation method, the support base is in contact with the outer peripheral edge portion of 3 mm. However, the support base can be set to be in contact with the outer peripheral edge portion of about 2 to 5 mm.

(Evaluation results)
The above-mentioned static pressure strength test was performed on each sample produced in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 1. In Example 1, the results for each of the two samples are shown, and in Examples 2 to 3, the results for each of the four samples are shown. In Comparative Example 1, the results for each of the five samples are shown.
As a result, when the average value of the intensity of each sample in Examples 1 to 3 and Comparative Example 1 was determined, the average value of Examples 1 to 3 was higher than the average value of Comparative Example 1. In particular, all results for the sample of Example 2 were better than Comparative Example 1.

Hereinafter, preferred embodiments in this embodiment will be additionally described.
[Appendix 1]
The method for producing a glass substrate, wherein the time for performing the implantation step is 1 minute or more and 60 minutes or less.
[Appendix 2]
The glass substrate is characterized in that one or more decorative layers are provided on the chemical strengthening layer.
[Appendix 3]
The glass substrate is used in at least one aspect selected from a cover glass for protecting a display panel and a touch panel.
[Appendix 4]
The glass substrate is a cover glass having a planar shape that substantially matches the contour shape in the planar direction of the image display area,
An image display panel having a substantially rectangular image display area;
An image display device comprising: the cover glass provided on the image display surface side of the image display panel.
[Appendix 5]
The glass substrate is a cover glass;
An image display panel having a substantially rectangular image display area;
A portable electronic device comprising: the cover glass provided on the image display surface side of the image display panel.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Chemical strengthening layer 3 Surface utilization ion implantation layer 4 Resist layer 4a Exposed part 4b Non-exposed part 4 'Resist pattern 5 Decorating layer 6 Photomask

Claims (9)

In the vicinity of the surface of the glass substrate containing the metal oxide, a substitution step of substituting the metal ion α of the metal oxide with a metal ion β having an ionic radius larger than the metal ion α;
An implantation step of performing a surface deutilization ion γ implantation treatment on the chemically strengthened layer formed in the vicinity of the surface of the glass substrate by the substitution step;
Have
In the chemical strengthening layer, at an arbitrary distance in the thickness direction from the main surface of the glass substrate, the ion concentration of Zn ²⁺ which is the surface depleted ions γ is set to be equal to or lower than the ion concentration of the metal ions β. The manufacturing method of the glass substrate of the cover glass for electronic devices characterized by these. The metal ion α is Na ^+, method of manufacturing a glass substrate for a cover glass for an electronic device according to claim 1, wherein the metal ions β is K ^+.   3. The electron according to claim 1, further comprising a removal step of removing a portion of the chemical strengthening layer located near the surface between the substitution step and the implantation step. A method for producing a glass substrate of a cover glass for equipment.   4. The cover glass for an electronic device according to claim 1, further comprising an acid cleaning step of performing an acid cleaning on the chemical strengthening layer between the replacement step and the injection step. 5. A method for producing a glass substrate. A substitution step of substituting the metal ion Na ⁺ of the metal oxide with the metal ion K ⁺ in the vicinity of the surface of the glass substrate containing the metal oxide;
For the chemical strengthening layer formed in the vicinity of the surface of the glass substrate by the replacement step, a removal step of removing a portion located in the vicinity of the surface by etching,
An acid cleaning step for performing acid cleaning on the chemically strengthened layer formed in the vicinity of the surface of the glass substrate by the replacement step;
After the removing step and the acid cleaning step, the chemical strengthening layer has an implantation step of implanting surface deutilized ions Zn ²⁺ ,
In the chemical strengthening layer, the ion concentration of the surface depleted ions Zn ²⁺ is set to be equal to or lower than the ion concentration of the metal ions K ⁺ at an arbitrary distance in the thickness direction from the main surface of the glass substrate. The manufacturing method of the glass substrate of the cover glass for electronic devices made into. The chemically strengthened layer formed in the vicinity of the surface of the glass substrate containing a metal oxide is
A metal ion α of the metal oxide;
A metal ion β having a larger ion radius than the metal ion α, and
An ion for deactivating the surface of the glass substrate, including a surface deactivating ion γ having a smaller ion radius than the metal ion β,
In the chemical strengthening layer, at an arbitrary distance in the thickness direction from the main surface of the glass substrate, the ion concentration of Zn ²⁺ which is the surface deutilization ion γ is equal to or lower than the ion concentration of the metal ion β. A glass substrate for a cover glass for electronic equipment.   The glass substrate of the cover glass for an electronic device according to claim 6, wherein the surface deutilized ions γ have an ion radius smaller than that of the metal ions α. The metal ion α is Na ^+, the glass substrate of the cover glass for an electronic device according to claim 6 or 7, wherein the metal ions β is K ^+. The glass substrate of a cover glass for an electronic device according to claim 8, wherein the K ⁺ concentration in the vicinity of the surface of the chemically strengthened layer is 5000 ppm or less.

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