JPWO2013137329A1 - GLASS SUBSTRATE FOR ELECTRONIC DEVICE GLASS AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

A method for producing a glass substrate for a cover glass for an electronic device, which can form an intervening surface interposed between the main surface and the end surface while maintaining high mechanical strength for the glass substrate for the cover glass for electronic device, and A glass substrate for a cover glass for an electronic device is provided. The manufacturing method includes a pair of main surfaces, an end surface disposed along a direction orthogonal to the pair of main surfaces, and a pair of interposed surfaces disposed between the pair of main surfaces and the end surfaces. A method for manufacturing a glass substrate for a cover glass for electronic equipment, comprising: an etching process step for performing an etching process on a glass substrate so that an intervening surface and an end surface are mirror surfaces.

Description

  The present invention relates to an electronic device including a cover glass for a portable device used as a cover member for a portable device (portable electronic device) and a cover glass for a touch sensor used as a cover member for an internal substrate in a touch sensor such as a pointing device. The present invention relates to a glass substrate for a cover glass and a manufacturing method thereof.

  As an electronic device, for example, a cover glass for a mobile device (cover glass for an electronic device) is formed on a cover member that forms a part of the exterior of a mobile device such as a mobile phone, a PDA (Personal Digital Assistant), a digital still camera, and a video camera. It is used. In recent years, cover glasses of various shapes have been produced in order to correspond to the casings and display screens of various shapes of mobile devices devised from the viewpoint of design, in addition to thinning and high functionality of portable devices. .

  If the outer edge of the glass substrate that is the base material of such a cover glass for portable devices is not subjected to any treatment, the boundary line between the main surface and the end surface becomes sharp, and cracks and Since chipping (chips) easily occurs, the required mechanical strength may not be obtained. Therefore, it is known to form an interposed surface (chamfered surface) interposed between the main surface and the end surface of the glass substrate of the cover glass for portable devices. Conventionally, as a method for forming an interposition surface, a method of forming an interposition surface by machining using a rotating brush (polishing brush) is known (Patent Document 1). As another method for forming an intervening surface, a method of forming an interposing surface by etching a glass substrate and a spacer laminated with an etchant composed of a mixture of hydrofluoric acid and sulfuric acid is known (Patent Document). 2).

JP 2009-256125 A JP 57-34049 A

  In recent years, in portable devices, display screens have become larger and display screens having a touch panel function have become popular, and accordingly, cover glasses for portable devices that protect display screens (hereinafter referred to as “cover glasses” as appropriate). Therefore, a higher mechanical strength has been demanded so that it can withstand a pressing operation on a display screen by a user, a drop of a portable device, and the like.

  However, in the conventional method of forming the interposition surface by machining, for example, the wire material having a high hardness of the polishing brush damages the end surface of the glass substrate of the cover glass and the end portion including the interposition surface. In some cases, microcracks remain at the end of the glass substrate. In this case, for example, when an external force is applied in the direction of bending the glass substrate, there is a possibility that the required mechanical strength cannot be maintained due to the progress of microcracks at the end.

  Microcracks can be removed by applying conventional etching to the edge of the glass substrate where microcracks exist, but the etched surface after microcrack removal has a very small amount due to processing marks. Unevenness (pear ground) can be formed. The minute irregularities are formed by forming a plurality of spherical minute concave portions and forming convex portions by contacting edges of adjacent concave portions. If such minute unevenness remains on the surface of the edge of the glass substrate, for example, when an external force is applied to the glass substrate in the direction of bending the main surface of the glass substrate, the unevenness on the surface of the edge As a result, stress concentration tends to occur, so that the required mechanical strength may not be maintained.

  Therefore, in one aspect of the present invention, for an electronic device that can form an intervening surface interposed between a main surface and an end surface while maintaining high mechanical strength for a glass substrate of a cover glass for portable devices. It aims at providing the glass substrate of a cover glass, and its manufacturing method.

The inventor who has faced the above-mentioned problems is able to remove microcracks or minute irregularities by mirroring the end surface and the interposition surface of the glass substrate of the cover glass for electronic equipment, so that the specific part on the end surface and the interposition surface It was found that the stress concentration of the glass substrate can be avoided and the mechanical strength of the glass substrate of the cover glass can be improved. In addition, since the surface properties are made extremely smooth by mirroring the end face and the intervening face, there is an effect that the appearance quality is improved.
Accordingly, a first aspect of the present invention provides a pair of main surfaces, end surfaces disposed along a direction orthogonal to the pair of main surfaces, and disposed between the pair of main surfaces and the end surfaces. A method of manufacturing a glass substrate for a cover glass for an electronic device having an end including a pair of interposed surfaces, wherein the pair of interposed surfaces are disposed between the pair of main surfaces and the end surfaces of the glass substrate. An intervening surface forming step to be formed; and a mirroring treatment step of performing an etching process on the glass substrate so that a surface of the end portion is a mirror surface.

  In the method for manufacturing a glass substrate for a cover glass for an electronic device, the interposed surface forming step is a process using a mechanical processing means, and in the mirroring process step, the processing is performed using the mechanical processing means. Etching may be performed so as to remove a damage layer that may occur at the end.

  In the method for manufacturing a glass substrate for a cover glass for electronic equipment, the intervening surface forming step is an etching process, and etching liquids having different compositions are used in the intervening surface forming step and the mirroring process step. Good.

  In the method for producing a glass substrate for an electronic device cover glass, in the interposition surface forming step, hydrofluoric acid or an acid having a larger acid dissociation constant than hydrofluoric acid is used as an additive with respect to hydrofluoric acid. In the mirroring treatment step, an etching solution in which an acid having a larger acid dissociation constant than hydrofluoric acid is added as an additive to hydrofluoric acid is used in the mirroring treatment step. The concentration of the etchant additive in the step may be higher than the concentration of the etchant additive in the interposition surface forming step. Furthermore, it is preferable that the mixing ratio of the substance amounts of hydrofluoric acid and the additive in the etching solution in the mirror finishing process is in the range of 10: 3 to 10:20 per 1 kg of the etching solution.

  In the method of manufacturing a glass substrate for a cover glass for electronic equipment, in the mirror surface treatment step, the glass substrate is immersed in an etching solution, and the glass substrate is swung in parallel with the thickness direction of the glass substrate. May be.

  In the method for manufacturing a glass substrate for a cover glass for electronic equipment, an opening that is performed before the mirror-finishing process and penetrates in the thickness direction of the glass substrate is formed in the glass substrate using a mechanical processing means. An opening forming step, and in the mirror finishing step, an etching process may be performed so that a damage layer that may be generated on an inner wall portion of the opening is removed by the opening forming step using the mechanical processing means. .

  In the method for manufacturing a glass substrate for a cover glass for electronic equipment, the method further includes a chemical strengthening step that is performed after the etching treatment step and performs chemical strengthening by ion exchange, and the etching treatment step is present on the inner wall portion of the opening. An etching allowance may be determined in advance so as to suppress breakage of the glass substrate in the chemical strengthening step caused by a damaged layer.

  In the method for manufacturing a glass substrate for a cover glass for electronic equipment, the etching treatment may be performed in a state where a plurality of the glass substrates are laminated via a protective material having etching resistance.

  According to a second aspect of the present invention, a pair of main surfaces, an end surface disposed along a direction orthogonal to the pair of main surfaces, and the pair of main surfaces and the end surfaces are disposed. The glass substrate of the cover glass for electronic devices which has an edge part containing a pair of interposition surface, Comprising: The said interposition surface and the said end surface are mirror surfaces, It is characterized by the above-mentioned.

  In the glass substrate of the cover glass for electronic equipment, it is preferable that an isotropic surface roughness Ra of the end face in two directions orthogonal to each other is 1 μm or less.

  In the glass substrate of the cover glass for electronic equipment, an opening is formed in the glass substrate, and an interposition surface is formed between the inner wall surface which is the surface of the inner wall portion of the opening and the pair of main surfaces. The intervening surface and the inner wall surface may be mirror surfaces.

  In the glass substrate for cover glass for electronic devices, the glass substrate may be aluminosilicate glass that can be chemically strengthened by ion exchange.

The perspective view of the glass substrate of the cover glass of embodiment. The cross-sectional enlarged view of the edge part of the glass substrate of the cover glass of embodiment. The figure which shows each process in the manufacturing method of the cover glass of embodiment. The perspective view of the laminated body of the glass substrate after a cutting process. The perspective view of the laminated body of the glass substrate after a shape processing process. The figure which shows the outline of the etching apparatus used at an etching process process. The figure which shows the relationship between the density | concentration of the sulfuric acid added to hydrofluoric acid in etching liquid, and the width | variety of the chamfering in an interposition part. The figure which shows the time-dependent change of the edge part of the laminated body of the glass substrate in the etching process process of embodiment. The figure explaining the rocking | fluctuation effect | action with respect to a laminated body in the etching process process of embodiment.

(1) Cover glass for portable device (electronic device) of the embodiment (hereinafter referred to as “cover glass” as appropriate)
A preferred usage form of the cover glass of the present embodiment is, for example, a cover glass used for protecting a display screen of a portable electronic device, particularly a mobile phone (mobile device). The cover glass of the present embodiment may have a desired shape, and is produced by forming a multilayer printed layer on the main surface by a known printing method on a glass substrate having the same shape. The cover glass needs to be made of glass that is thin and has high mechanical strength in order to satisfy the specifications for device drop or operation input to the display screen (operation input as a touch panel function). Reinforcement has been made.

  In FIG. 1A and FIG. 1B, an example of the external appearance of the glass substrate of the cover glass of this embodiment is shown. FIG. 1A is a perspective view of an exemplary glass substrate 1, and FIG. 1B is an enlarged view of a cross section of an end (edge) of the glass substrate 1 shown in FIG. 1A. The thickness T of the glass substrate 1 is not particularly limited, but it is usually preferably 1 mm or less, and 0.7 mm or less, from the viewpoint of suppressing an increase in the weight of various devices to which the cover glass is assembled and reducing the thickness of the devices. It is more preferable that The lower limit value of the plate thickness T is preferably 0.1 mm or more from the viewpoint of ensuring the mechanical strength of the glass substrate. The outer shape of the glass substrate 1 can be appropriately set according to the portable device to be incorporated. As illustrated in FIG. 1A, the glass substrate 1 is formed with an opening 1h for voice input / output, such as a receiver and a microphone, as necessary. In addition, you may provide the recessed part (it is a notch shape of planar view) recessed in the edge part of a glass substrate to the surface direction center side of a main surface.

The glass substrate of the present embodiment is selected from, for example, (1) SiO ₂ and Al ₂ O ₃ , Li ₂ O, and Na ₂ O that are used for producing a sheet glass using a downdraw method, a float method, or the like. It is preferable to use a known glass material such as an aluminosilicate glass containing at least one alkali metal oxide and (2) soda lime glass used for producing a sheet glass using a float method or the like. A compressive stress layer is formed by chemical strengthening on the surface layer portions on the front side and the back side of the glass substrate, respectively. This compressive stress layer is an altered layer in which a part of the alkali metal originally contained in the glass material constituting the glass substrate is replaced with an alkali metal having a larger ionic radius. For example, sodium ions contained in the glass material constituting the glass substrate of this embodiment are replaced with potassium ions.

The aluminosilicate glass includes at least each of oxides of silicon, aluminum, and sodium from the practical viewpoints such as manufacturability of plate glass, mechanical strength, and chemical durability. It is more preferable that the glass contains a glass having a high content and a relatively small content of aluminum oxide. Examples of such an aluminosilicate glass, for example, SiO ₂ is 58 to 75 wt%, _Al 2 _{O 3} is 4-20 wt%, Li ₂ O is 0 to 10 wt%, Na ₂ O 4 to 20 Aluminosilicate glass containing wt% as a main component can be used.

  As shown in FIG. 1B, the glass substrate 1 of the present embodiment includes a pair of main surfaces 1p, an end surface 1t arranged along a direction orthogonal to the pair of main surfaces 1p, and a pair of main surfaces 1p. It has a pair of interposition surface 1c arrange | positioned between the end surfaces 1t. The intervening surface 1c is provided in order to avoid a decrease in mechanical strength due to the occurrence of microcracks during the manufacturing process of the cover glass or when the cover glass is assembled to a portable device. Similar to the intervening surface 1c, an interposing surface is also formed on the glass substrate 1 between the inner wall surface 1w of the opening 1h and the pair of main surfaces 1p.

The end surface 1t and the intervening surface 1c are mirror surfaces in order to maintain high mechanical strength with respect to the cover glass. In addition, the mirror surface is generally “a surface that is finished so as to be mirror-like on a pear ground having countless fine irregularities.” (Source: Cutting / Grinding / Polishing Glossary, Abrasive Grain Edited by the Processing Society, published by the Industrial Research Council (December 5, 1995)). For example, when the surface roughness (calculated average roughness Ra) in two directions orthogonal to each other on a certain surface is 0.1 μm or less, the surface may be defined as a mirror surface (or smooth surface). That is, it may be defined as a mirror surface if the isotropic surface roughness Ra in two directions orthogonal to each other is 0.1 μm or less.
Moreover, as shown in FIG. 1B, at the end portion of the cover glass of the embodiment, the boundary portions b11 and b12 between the main surface 1p and the interposed surface 1c, and the boundary portions b21 and b22 between the interposed surface 1c and the end surface 1t are Both are rounded. In addition, in order to suppress generation | occurrence | production of the stress concentration in these boundary parts, it is preferable that all have the curvature radius of boundary part b11, b12 and boundary part b21, b22 in the range of 30-200 micrometers.

(2) Manufacturing method of glass substrate of cover glass of embodiment Hereinafter, the manufacturing method of the glass substrate of the cover glass for portable devices of this embodiment is demonstrated. FIG. 2 is a diagram sequentially illustrating each step in the method for manufacturing the glass substrate of the cover glass for portable devices of the present embodiment. Hereinafter, each step will be described.

(2-1) Sheet glass laminating process The sheet glass laminating process is performed by laminating a large size sheet glass having a predetermined size, for example, produced by a downdraw method or a float method, with a protective material interposed therebetween. It is the process of producing the laminated body of glassy glass.

  The protective material interposed between the glass sheets is preferably a temporary material that has a predetermined adhesive strength and can be peeled later. As described above, by using a temporary attachment material as the protective material, it becomes difficult to separate the glass sheets constituting the laminate, so that the laminate can be handled easily. As such a temporary bonding material, for example, an ultraviolet curable resin (UV curable resin) is easily solidified by irradiation with ultraviolet rays having a predetermined wavelength, and thus has an advantage that the bonding operation is easy. As the ultraviolet curable resin, a resin that can easily peel off the glass sheet bonded with hot water, heat, or an organic solvent is preferable. In addition to the ultraviolet curable resin, a wax, a light curable resin, a visible light curable resin, or the like can be used as the temporary material. Since the wax softens at a predetermined temperature to become a liquid and becomes a solid at room temperature, it is easy to bond and separate.

  Such a temporary attachment material may be provided in a roll shape, and a temporary attachment roll is temporarily attached to the entire surface of the large-sized plate-like glass by rotating and temporarily cut, and then on the temporary attachment material. Repeat to place the next plate glass. The number of laminated sheet glasses is, for example, about 10 to 100. When the temporary attachment material is a UV curable resin, the temporary attachment material is cured by irradiating the laminated sheet of glass sheets with ultraviolet rays. In addition, when sticking a spacer instead of a temporary attachment material, the thin spacer of a resin material, a fiber material, a rubber material, a metal material, and a ceramic material can be used.

  Since the protective material comes into contact with the etching solution used in the etching process described later, the protective material is made of a material that is not dissolved or removed by the etching solution (that is, etching resistance). For example, when hydrofluoric acid is the main component as the etchant, the protective material is made of a material that is hardly soluble or insoluble in hydrofluoric acid.

  In addition, when the thickness of the temporary attachment material is too thick, for example, 200 μm or more, chipping (chips) in a subsequent cutting step or the like becomes a problem. On the other hand, when the thickness of the temporary bonding material is, for example, 10 μm or less, it may be difficult to peel off the glass substrate. Therefore, the thickness of the temporary bonding material is preferably 10 to 200 μm, more preferably 20 to 80 μm.

(2-2) Cutting process Next, the laminated body on which large-sized plate-like glass is laminated is divided (cut) horizontally and vertically by a disk cutter (diamond disk) to produce a laminated body of small glass substrates. The size of the glass substrate of this small piece is a little larger than the cover glass finally obtained. FIG. 3 shows a perspective view of a small glass substrate laminate 10A obtained by the cutting process. As shown in FIG. 3, the laminated body 10A has a structure in which a protective material 100A and a glass substrate 1A are sequentially laminated. On the side surface of the laminated body 10A after the cutting step, the end surfaces of the protective material 100A and the glass substrate 1A are on the same plane.

(2-3) Opening Formation Step Next, an opening corresponding to the opening 1h to be provided in the cover glass is formed by machining on the glass substrate laminate 10A. In addition, if an opening is unnecessary in the cover glass, an opening forming step is also unnecessary. In the opening forming step, an opening having a desired shape is formed by NC processing using a mechanical processing means such as a drill.

(2-4) Shape processing step Next, a shape processing step is performed. The shape processing step is a step of machining the laminated body 10A so that the outer shape of the laminated body 10A of the glass substrate becomes the outer shape of the cover glass. In the shape processing step, for example, the outer edge of the glass substrate laminate 10A is ground (NC processed) using a grinder or the like to obtain a desired outer shape. An exemplary perspective view of the glass substrate laminate 10B obtained by the shape processing step is shown in FIG. As shown in FIG. 4, the laminated body 10B has a structure in which a protective material 100B and a glass substrate 1B are sequentially laminated. On the side surface of the laminated body 10B after the cutting step, the end surfaces of the protective material 100B and the glass substrate 1B are on the same plane. The end surface of the glass substrate after the shape processing is a machined surface having a relatively rough surface property. In addition, in the laminated body 10B shown in FIG. 4, an example of the opening 10H formed by the opening formation process is shown.

(2-5) Etching treatment process (edge treatment process)
The etching process is a process in which an etching process is performed using an etching apparatus 20 shown in FIG. 5 on the end of each glass substrate 1B constituting the laminated body 10B.
The etching processing apparatus 20 will be described with reference to FIG. As shown in FIG. 5, in the etching processing apparatus 20, the liquid tank 3 filled with the etching liquid L1 is provided. The etching solution L1 is not particularly limited as long as it contains at least hydrofluoric acid, but if necessary, an acid having a larger acid dissociation constant than hydrofluoric acid, such as sulfuric acid or hydrochloric acid, is added as an additive. Also good.

  The liquid tank 3 includes a holding mechanism for holding the laminated body 10B of the glass substrate, a liquid circulating apparatus in the tank such as a bubbling mechanism, and an oscillation (not shown) for oscillating the laminated body 10B. A mechanism 5 is preferably provided. A preferable example of swinging of the laminated body 10B by the swinging mechanism 5 is as shown by an arrow in FIG. 5 in the stacking direction of the stacked body 10B (that is, in the thickness direction of the glass substrate). That is, the laminated body 10B is swung at a predetermined number of times of rocking.

In the laminated body 10B, etching proceeds from the end surface of the glass substrate in contact with the etching solution in the liquid tank 3, but as the reaction proceeds, an insoluble or hardly soluble salt (for example, M ₃ [AlF ₆ ]) as a reaction product. , M ₃ [AlF ₆ ] ₂ , M: alkali metal, alkaline earth metal). This insoluble or hardly soluble salt can be removed from the end face of the glass substrate by swinging the laminate 10B and further by the liquid circulation system of the etching processing apparatus 20. The liquid circulation system of the etching processing apparatus 20 includes an overflow tank 4 provided in the upper part of the liquid tank 3, a pipe 8, a filtering device 6 for removing reaction products from the etching liquid, and a circulation pump 7. ing.

In this liquid circulation system, the etching solution in the liquid tank 3 moves from the liquid tank 3 to the overflow tank 4 and is sent to the filtering device 6 through the pipe 8. Then, the reaction product by etching is captured and removed by the filtering device 6. The etching solution from which the reaction product has been removed is returned to the liquid tank 3 again from the bottom surface of the liquid tank 3 by the circulation pump 7.
Here, the filtering device 6 is a device for selectively removing the reaction product from the etching solution. The filtering device 6 preferably has a configuration capable of selectively removing reaction products from the etchant, for example, a device configuration capable of realizing selective removal by centrifugation, selective removal by a sedimentation tank, and the like. .

  By adopting the rocking mechanism 5 of the glass substrate laminate 10B and the liquid circulation system, it becomes difficult for the reaction product of the etching to be deposited on the edge of the glass substrate of the laminate 10B. No physical treatment such as scrub cleaning is required. Therefore, in this step, it is possible to eliminate the possibility of mechanical damage to the edge of the glass substrate that may occur due to physical processing such as hand scrub cleaning after etching.

  Hereinafter, as a preferable aspect of the etching process using the etching processing apparatus 20, a mirroring process for mirroring the end surface and the interposition surface and an interposition for forming the interposition surface are performed on the laminated body 10B after the shape processing step. An etching process including a two-stage process including a surface forming process (a two-stage etching process) will be described. In the two-stage etching process, the mirroring process and the intervening surface forming process are continuously performed using different etching processing apparatuses 20. The purpose is to achieve the formation of the intervening surface of the glass substrate and the mirroring of the end and intervening surface by performing two-stage etching.

As a result of trial and error of the degree of intervening surface formation (chamfering amount) and the degree of mirroring (for example, surface roughness) with respect to the composition of different etching solutions, the inventor found that the composition in the intervening surface forming step and the mirroring treatment step Have found that it is preferable to use different etching solutions. Specifically, it is preferable to change the mixing ratio of hydrofluoric acid and another acid (additive) between the etching solution for the intervening surface forming step and the etching solution for the mirror finishing process. Here, an example of the relationship between the amount of chamfering obtained by etching and the amount of sulfuric acid added in the etching solution is shown in FIG. The graph of FIG. 6 is a graph when hydrofluoric acid per kg of the etching solution is 10 [mol] and the amount of sulfuric acid (H ₂ SO ₄ ) added per kg of the etching solution is changed. From FIG. 6, it is understood that the amount of sulfuric acid to be added is preferably 3 to 4 [mol] or less, assuming that the chamfering amount required for the glass substrate of the cover glass for portable devices is at least about 60 μm.

  On the other hand, it was found that when the amount of sulfuric acid added to the etching solution is at least 3 to 4 [mol] or more, the end surface of the glass substrate is smoothed to become a mirror surface. In other words, it was found that the concentration of the etching solution additive in the mirror surface treatment step is preferably higher than the concentration of the etching solution additive in the intervening surface forming step. When the concentration of the acid as an additive in the etching solution is low, the interposition surface at the end of the glass substrate becomes good (that is, the chamfering amount of the interposition surface can be increased) and functions as chemical etching. On the other hand, when the concentration of the acid as an additive in the etching solution is high, the end surface of the glass substrate is smoothed and functions as a chemical polishing that provides a good end surface with almost no unevenness.

  More specifically, the mixing ratio (mol ratio) of hydrofluoric acid and the additive in the etching solution in the mirror finishing step is in the range of 10: 3 to 10:20 per kg of the etching solution. Is preferable, and it is more preferable to be within the range of 10: 4 to 10: 9. On the other hand, the mixing ratio of the hydrofluoric acid and the additive in the etching solution in the intervening surface forming step may be lower than that in the mirroring treatment step. Note that the etchant in the intervening surface forming step may be only hydrofluoric acid (that is, no additive may be added).

  Hereinafter, an example of the procedure of a specific two-stage etching process will be described with reference to FIG. Steps S1 to S4 in FIG. 7 conceptually show the change in the surface property of the end portion of the glass substrate 1B in the mirror finishing process and the change in the end shape of the glass substrate 1B in the interposition surface forming step in order. FIG. Step S1 in FIG. 7 shows the laminated body 10B in the initial state (that is, after the shape processing step), and the end surfaces of the protective material 100B and the glass substrate 1B constituting the laminated body 10B are the shape processing that is the previous step. The same surface (machined surface) is obtained by machining in the process.

First, in the mirror finishing process, the etching solution prepared so that the concentration of the additive becomes the above-described one fills the liquid tank 3 of the etching processing apparatus 20, and sets the laminate 10 </ b> B in the swing mechanism 5. Then, the laminate 10B is swung for a predetermined time (for example, 3 minutes) by the swing mechanism 5 with a predetermined swing amount and swing frequency. In this mirror finishing process, chemical polishing is performed to smooth the end face of the glass substrate and form a good end face with almost no unevenness. As a result, as shown in step S <b> 2 of FIG. 7, the end surface and the interposition surface of each glass substrate 1 </ b> B become mirror surfaces from which microcracks and minute irregularities are removed.
In addition, when the opening 10H is formed in the opening forming step, the etching liquid is filled in the opening, and therefore, the mirror surface treatment step causes the inside of the opening of each glass substrate 1B constituting the laminated body 10B. Etching is performed so that the wall surface and the intervening surface between the inner wall surface and the main surface are mirror surfaces.

  Next, in the intervening surface forming step, it was filled with an etching solution prepared so that the concentration of the additive was as described above (that is, an etching solution having a lower concentration of additive than in the case of the mirroring treatment step), The laminated body 10B is transferred to a liquid tank 3 different from that used in the mirror finishing process, and the laminated body 10B is moved for a predetermined time (for example, 3 minutes) by the rocking mechanism 5 with a predetermined rocking amount and the number of rocking times. Rock. In this intervening surface forming step, chemical etching is performed to polish the end surface of the glass substrate and form an interposing surface that interposes the main surface and the end surface. As a result, as shown in step S3 of FIG. 7, etching proceeds from the end face 1t of each glass substrate 1B constituting the laminated body 10B. That is, since the protective material 100B has etching resistance, it is not dissolved / removed, but the end surface 1t of the glass substrate 1B in contact with the etching solution is dissolved / removed more than in the state of step S2. As the etching progresses, for example, the end surface 1t of the glass substrate 1B is dissolved and removed to the inside of, for example, about 20 to 100 μm from the end surface of the protective material 100B. That is, as shown in step S3 of FIG. 7, a pair provided on each glass substrate 1B so that the position of the end surface 1t of each glass substrate 1B constituting the laminated body 10B changes inward in the plane direction of the main surface 1p. The glass substrate is dissolved in the etching solution between the protective materials 100B of each other, whereby a protruding portion 100j (a portion of the protective material 100B protruding outward from the end surface 1t of the glass substrate) is formed on the pair of protective materials 100B. It is formed.

Further, by the swinging action of the etching processing apparatus 20, the etching solution penetrates inward at the molecular level to the interface (indicated by BD in FIG. 7) between the protective material 100B and the glass substrate 1B, and thus in step S4 of FIG. As shown, an interposition surface 1c is formed. At this time, since substantially isotropic etching is performed, the boundary portion between the main surface 1p and the interposition surface 1c and the boundary portion between the interposition surface 1c and the end surface 1t are all rounded ( (See FIG. 1B).
In addition, when the opening 10H is formed in the opening forming step, the etching liquid is filled in the opening, so that the inside of the opening of each glass substrate 1B constituting the laminated body 10B is formed by the intervening surface forming step. An intervening surface is formed between the wall surface and the main surface.

The swinging action of the etching processing apparatus 20 is schematically shown in FIG. In the etching processing apparatus 20, when the rocking is performed in parallel with the stacked body 10B in the vertical direction, that is, the thickness direction of the glass substrate, the protrusion 100j of the protective material 100B is formed. As shown in FIG. 8, when the laminated body 10B moves downward, a flow F1 of the etching solution directed toward the end face 1t of the glass substrate is generated, and when the laminated body 10B moves upward, it faces the end face 1t of the glass substrate. A flow F2 of the etching solution is generated. As a result, the etching solution penetrates inward at the molecular level along the interface BD (see FIG. 7) between the protective material 100B and the glass substrate 1B, and dissolves and removes the portion interposed between the main surface 1p and the end surface 1t. As a result, an interposition surface 1c is formed between the main surface 1p and the end surface 1t. The width (chamfering amount) in the in-plane direction of the formed interposed surface 1c is, for example, about 70 to 100 μm.
In the etching processing apparatus 20, the rocking direction of the stacked body 10B is not limited to the above-described direction, and may be other rocking directions. For example, you may rock | fluctuate in the direction parallel to the main surface of the glass substrate 1B.

  Note that it is preferable to control the amount of oscillation of the stacked body 10B in the stacking direction in order to cause the etching solution to flow sufficiently in the opening 10H of the stacked body 10B so that the intervening surface in the opening is satisfactorily formed. For example, the rocking condition is at least twice the sum of the thicknesses of the glass substrate and the protective material to be etched (in the example shown in FIG. 5, the length in the stacking direction of the stacked body 10B). The number of movements is preferably 1 to 60 times / minute. Further, the number of oscillations is more preferably 10 to 30 times / minute in order to further enhance the circulation effect of the etching solution.

  In the etching processing apparatus 20, the rocking direction of the stacked body 10B is not limited to the above-described direction, and may be other rocking directions. For example, you may rock | fluctuate in the direction (namely, front-back, left-right direction) parallel to the main surface of the glass substrate 1B. What is necessary is just to move an etching liquid relatively with respect to a glass substrate or its laminated body, and the rocking | fluctuation direction is not ask | required. By moving the etching solution relative to the glass substrate, the etching solution flows toward the end surface, so that the etching solution penetrates into the interface between the protective material and the glass substrate, and an interposition surface is formed. .

  Note that the manufacturing method of the present embodiment is not limited to the two-stage etching process described above. For example, the intervening surface has already been subjected to mechanical processing by brush polishing on the laminated body 10B after the shape processing step (not shown; see, for example, the above cited reference 1) or mechanical grinding processing using a general-purpose grindstone. When the laminated body 10 </ b> B on which the is formed is an object to be etched, it is not necessary to form an intervening surface by etching. In that case, the etching process may be for the purpose of mirroring only the end face and the intervening surface. Similar to the mirroring process described above, hydrofluoric acid and an additive (with an acid dissociation constant). The mixing ratio (mol ratio) with the hydrofluoric acid is preferably in the range of 10: 3 to 10:20 per kg of the total amount of the etching solution, and in the range of 10: 4 to 1:12. More preferably. In addition, the rocking | fluctuation conditions of a mirror-finishing process are the same as the rocking | fluctuation conditions of an interposition surface formation process.

Moreover, in the said etching process process, although the case where a mirror-finishing process process and an interposition surface formation process were performed in that order was demonstrated, you may replace the order of a mirror-finishing process process and an interposition surface formation process. That is, the intervening surface forming step may be performed first, followed by the mirroring process step.
Here, in the etching process (mirror finishing process or intervening surface forming process), the etching process is performed so as to suppress the breakage of the glass substrate in the chemical strengthening process caused by the damaged layer that may exist on the inner wall portion of the opening. The takeover of is decided beforehand. The margin (dissolution amount) of the inner wall portion of the opening in this etching step may be 20 to 200 μm as in the case of the end face 1t of the glass substrate 1B. Moreover, it is preferable to set it as 50 micrometers or more in order to remove a damage layer more reliably, and to improve production efficiency, it is 100 micrometers or less.

(2-6) Peeling Step The peeling step is a step of peeling the glass substrate laminates 10B one by one and separating the individual glass substrates from the laminate 10B. The peeling method in the peeling process depends on the characteristics of the protective material. For example, in the protective material (temporary bonding material) made of an ultraviolet curable resin, the peeling method is performed in an environment of warm water (80 to 90 degrees Celsius). There is a protective material. In such a case, the laminated body 10B can be peeled (separated) on each glass substrate by immersing the laminated body 10B in a container containing warm water.

(2-7) Chemical strengthening process Next, a chemical strengthening process is performed.
In the chemical strengthening step, a plurality of glass substrates are loaded into a cassette (holder), and the cassette is immersed in a chemical strengthening treatment liquid containing a molten salt. Thereby, one or more kinds of alkali metals contained in the glass substrate are subjected to an ion exchange treatment with the alkali metal of the molten salt to form a compressive stress layer on the surface layer portion of the glass substrate.

The composition and temperature of the molten salt, and the immersion time can be appropriately selected according to the glass composition of the glass substrate, the thickness of the compressive stress layer formed on the surface layer portion of the glass substrate, etc., but the glass composition of the glass substrate has been described above. In the case of an aluminosilicate glass or soda lime glass, it is preferable to use a low-temperature ion exchange method in which the treatment temperature of the chemical strengthening treatment liquid is usually 500 ° C. or lower. This is because the high-temperature ion exchange method in which ion exchange is performed in the temperature range above the annealing point of the glass does not provide a mechanical strength as high as that of the low-temperature ion exchange method. This is because it is difficult to obtain a glass substrate that is suitable for a cover glass for portable devices because of the erosion of the glass and its transparency. For example, in the chemical strengthening step of the present embodiment, the composition and temperature of the molten salt and the immersion time are preferably selected from the ranges exemplified below.
-Composition of molten salt: Potassium nitrate or a mixed salt of potassium nitrate and sodium nitrate-Temperature of molten salt: 320 ° C to 470 ° C
・ Immersion time: 3 minutes to 600 minutes

(2-8) Final cleaning step In the final cleaning step, for example, acid cleaning, alkali cleaning, rinsing with pure water, or IPA (isopropyl alcohol) performed in a state where a plurality of chemically strengthened glass substrates are placed on a pallet. Including at least one of washing.

  In the following, the present invention is further illustrated by examples. However, this invention is not limited to the aspect shown in the Example.

  An aluminosilicate glass including a glass containing at least silicon, aluminum, and sodium oxides, and particularly containing a large amount of silicon oxide and a relatively small amount of aluminum oxide is formed by a downdraw method to obtain a thickness of 0. Molded into 5 mm plate glass. The surface roughness (arithmetic mean roughness Ra) of the main surface of the sheet glass formed by the downdraw method was 10 nm when examined by an atomic force microscope.

The plate-like glass is cut into a rectangular glass substrate having a size of 370 mm × 470 mm, and the cut glass substrate is laminated with an ultraviolet curable resin material as a temporary attachment material uniformly attached to the surface thereof to form a laminate. Produced. Furthermore, the laminated body was irradiated with visible light to cure the resin material so that the laminated glass substrates were not separated.
[Laminated bodies of Examples 1 to 5 and Comparative Examples 1 and 2]
-Number of laminated glass substrates: 20-Temporary material: UV curable resin material-Temporary material thickness: about 20 μm

After producing the laminates of the examples and comparative examples, the mirror treatment process and the intervening plane forming process are sequentially performed on the end portions of the glass substrates constituting the laminate using the etching processing apparatus shown in FIG. A staged etching process was performed. Different etching processing apparatuses were used in the mirror finishing process and the intervening surface forming process. Etching conditions were as follows. The mixing ratio of hydrofluoric acid (HF) in the etching solution and sulfuric acid (H ₂ SO ₄ ) as an additive in each step is as shown in Table 1.
[Etching conditions for mirror finishing process]
Etching solution temperature: 40 ° C
・ Circulated flow rate: 20 L / min ・ Oscillation time: 3 minutes ・ Oscillation amount: 120 mm (pp)
・ Oscillation frequency: 30 times / min [Etching condition of the intervening surface forming step]
-Etching solution temperature: 35 ° C
・ Circulating flow rate: 10 L / min ・ Oscillation time: 5 minutes ・ Oscillation amount: 20 mm (pp)
・ Oscillation frequency: 25 times / minute

Next, the laminated body was taken out from the etching processing apparatus, immersed in warm water (80 to 90 degrees Celsius), and separated into a plurality of glass substrates. At this time, no abnormality was found on the surface of each glass substrate. About the obtained glass substrate, the chamfering amount of the interposition surface and the surface roughness of the end surface and the interposition surface were measured and evaluated. The measuring method and evaluation criteria of the chamfering amount of the intervening surface, the end surface, and the surface roughness of the interposing surface were as follows.
The edge of the glass substrate is magnified 200 times with an optical microscope, and the amount of chamfering of the intervening surface is measured. When the thickness is 70-100 μm, “◯”, when 50-70 μm, “Δ”, when 50 μm or less Evaluated as “x”. “◯” or “Δ” is acceptable.

  Further, the surface roughness of the end surface and the intervening surface is represented by an arithmetic average roughness Ra defined by JIS B0601: 2001, for example, measured by a Keyence laser microscope (VK-9700), and defined by JIS B0633: 2001. Calculated by the method. At this time, the arithmetic average roughness Ra was calculated in two directions orthogonal to each other on each of the end face and the intervening face. As a result, “◯” was evaluated when 0.05 μm or less in both directions, “Δ” when 0.1 μm or less in both directions, and “X” when larger than 0.2 μm in at least one direction. . “◯” or “Δ” is acceptable.

（※１）ＨＦとＨ_２ＳＯ_４の混合比は、エッチング液総量１ｋｇ当たりの物質量（ｍｏｌ）の比である。

(* 1) The mixing ratio of HF and H ₂ SO _{4 is} the ratio of the amount of substance (mol) per 1 kg of the total amount of the etching solution.

From the evaluation results shown in Table 1, when the concentration of H ₂ SO ₄ in the etching solution in the mirror finishing process is higher than the concentration of H ₂ SO ₄ in the etching surface formation step (Examples 1 to 5) In addition, it can be seen that both the chamfering amount of the intervening surface and the surface roughness of the end surface and the interposing surface are improved. In particular, it was particularly favorable when the mixing ratio of HF and H ₂ SO ₄ was in the range of 10: 4 to 10:20. About the glass substrate in the case of Examples 1-5, when the end surface and the intervening surface were magnified 200 times with a laser microscope and observed, microcracks and minute irregularities were not observed, and the surface property that can be said to be extremely smooth and mirror surface. Met. On the other hand, in the comparative example, the concentration of H ₂ SO ₄ was not appropriate in any step, and the chamfered amount of the intervening surface, or the surface roughness of the end surface and the interposing surface did not become good.

  Furthermore, about the glass substrate of the comparative example 1 and Examples 1-5, the fracture | rupture load was measured with the 4-point bending test method according to, and the 4-point bending strength of the glass substrate was computed. The external size of the evaluation sample is 100.4 mm × 47.4 mm. As a result, in the case of Comparative Example 1, the breaking load was about 500 MPa, and in each of Examples 1 to 5, the breaking load exceeded 600 MPa. That is, it was confirmed that the mechanical strength was improved when the end surface and the intervening surface of the glass substrate were mirror surfaces as compared to the non-mirror surface.

[Comparative Example 3 and Examples 6 and 7]
Next, the manufacturing conditions of Example 1 were changed to create a glass substrate with an opening. Specifically, a glass substrate laminate was prepared in the same manner as in Example 1, and the edge of the glass substrate laminate was used with a brush and loose abrasive grains by the method described in JP-A-2009-256125. And polished. And a pair of interposition surface was formed in the edge part of the glass substrate in a laminated body, the laminated body was isolate | separated, and chemical strengthening was given, and the glass substrate of the comparative example 3 was obtained. In addition, in the manufacturing process of Comparative Example 3, before polishing the end portion, an opening having a long hole shape in plan view of 1.3 mm × 10.0 mm was formed at an interval of 30 mm from one end in the longitudinal direction of the cut laminate. It formed with the mechanical processing means, it grind | polished about the edge part and the inner wall part of opening using the brush and the loose abrasive grain, the laminated body was isolate | separated, and the glass substrate after isolation | separation was chemically strengthened. Thus, the glass substrate without an opening and the glass substrate with an opening were obtained as a glass substrate of the comparative example 3.

  Moreover, after changing the manufacturing process of the comparative example 3 in part and polishing the edge part of a laminated body using a brush and a loose abrasive grain, the same conditions as the mirror-finishing process of Example 3 are applied to the edge part of a laminated body. The mirror surface treatment was performed by etching. And the laminated body was isolate | separated and the glass substrate after isolation | separation was chemically strengthened and the glass substrate of Example 6 was obtained. In addition, in the manufacturing process of the glass substrate of Example 6, a 1.3 mm × 10.0 mm long hole in plan view was formed in a laminated state, and the inner wall of the opening was mirror-finished (etched). A glass substrate of Example 6 with an opening was obtained.

Further, a glass substrate of Example 7 was obtained under the same production conditions as in Example 3. Also, in the process of manufacturing the glass substrate of Example 7, a 1.3 mm × 10.0 mm long hole in plan view was formed in a laminated state, and the inner wall of the opening was mirror-finished (etched). A glass substrate of Example 7 with an opening was obtained.
And the breaking load was measured with respect to the glass substrate of Example 6, 7 and the comparative example 3 by the 4-point bending test method according to JIS-R1601, and the 4-point bending strength of the glass substrate was calculated | required. The results are shown in Table 2 below. The number of samples is 100, and Table 2 shows the range of values obtained by the four-point bending test.

  As shown in Example 6 and Comparative Example 3 in Table 2, even when a pair of intervening surfaces are formed at the end of the glass substrate by brush polishing, by performing a mirroring process by etching process thereafter, It was confirmed that the mechanical strength of the glass substrate could be improved. In addition, it was confirmed that the strength can be improved more remarkably in the case with an opening. Furthermore, as shown in Example 6 and Example 7, in place of brush polishing, the mechanical strength can be improved most when the interpolated surface is formed by the etching process after the mirroring process is performed in advance. Was confirmed.

[Comparative Examples 4 and 5 and Example 8]
Next, a pair of intervening surfaces was formed at the end portion of the glass substrate by a single-wafer method, which is a method of performing each process in units of one glass substrate, by grinding using a general-purpose grindstone. Thereafter, chemical strengthening was performed on the glass substrate after grinding, and a glass substrate of Comparative Example 4 was obtained. Moreover, in the manufacturing process of the comparative example 4, after grind | polishing the edge part of a glass substrate using a brush and a loose abrasive grain, the chemical treatment was given and the glass substrate of the comparative example 5 was obtained. In the manufacturing process of the glass substrates of Comparative Examples 4 and 5, respectively, using mechanical processing means, a 1.3 mm × 10.0 mm long hole in plan view was formed, chemically strengthened, and with an opening The glass substrates of Comparative Examples 4 and 5 were obtained.

  Moreover, after partially changing the manufacturing process of the glass substrate of Comparative Example 4 and performing grinding using a general-purpose grindstone, a mirror surface by etching under the same conditions as the mirroring treatment of Example 3 is applied to the end of the glass substrate. Was applied. And the glass substrate of Example 8 was obtained by chemically strengthening the glass substrate. Further, in the manufacturing process of the glass substrate of Example 8, an opening having a long hole shape in plan view of 1.3 mm × 10.0 mm was formed, and the inside of the opening was mirror-finished (etching process) to provide an example with an opening. 8 glass substrates were obtained.

  And about these samples, the fracture load was measured by the 4-point bending test method according to JIS-R1601, and the 4-point bending strength of the glass substrate was calculated | required. The results are shown in Table 3 below. The number of samples is 100, and Table 3 shows the range of values obtained by the four-point bending test.

  As shown in Example 8 and Comparative Examples 4 and 5 in Table 3, even when an intervening surface is formed at the end of the glass substrate by a single wafer method, by performing a mirroring process by an etching process thereafter It was confirmed that the mechanical strength of the glass substrate could be improved. Further, it was confirmed that the brush polishing method as in Comparative Example 5 could not sufficiently polish the inner wall portion of the opening, and the damaged layer present on the inner wall portion of the opening could not be removed.

  Here, in the glass substrate (with an opening) created by the method of Example 8, the yield in the chemical strengthening process was about 98%. On the other hand, in the glass substrate (with an opening) created by the method of Comparative Example 5, the yield in the chemical strengthening process was about 40%. Specifically, in the glass substrate prepared by the method of Comparative Example 2, it was confirmed that chipping and cracking around the slit occurred during the chemical strengthening process. This is due to the thermal expansion of the glass substrate during chemical strengthening and the change in stress associated with ion exchange during chemical strengthening, which causes microcracks in the damage layer on the inner wall of the opening when the opening is formed by machining such as a drill. This is because of progress. In addition, it was confirmed that the yield in the chemical strengthening process is significantly reduced by the influence of the damaged layer when the damaged layer is not removed not only on the inner wall portion of the opening but also on the outer periphery of the glass substrate.

  Therefore, in the case of performing at least one of outer shape processing and opening formation by a machining method, it is necessary to remove a damaged layer due to machining by an etching process, and by removing a damaged layer due to machining by an etching process. Not only the mechanical strength but also the yield can be improved.

  As mentioned above, although embodiment of this invention was described in detail, the manufacturing method of the glass substrate of the cover glass for electronic devices of this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, it is various improvement. Or you can change it.

  For example, in the above-described embodiment, the example in which the opening forming process, the shape processing process, and the etching process process are performed on a stacked body of a plurality of glass substrates has been described. However, the processing method of the present invention is not limited to such a lamination method, and may be a method (single wafer method) in which each process is performed in units of one glass substrate. Moreover, after performing at least one of an opening formation process and a shape processing process by a single wafer system, a glass substrate may be laminated | stacked and a laminated body may be etched.

  Moreover, in embodiment mentioned above, the example which applied this invention to the manufacturing method of the glass substrate of the cover glass for portable devices was demonstrated. However, you may apply this invention to the manufacturing method of the glass substrate of the cover glass for touch sensors used as a cover member of the internal substrate in a touch sensor.

Claims (13)

A pair of main surfaces, an end surface disposed along a direction orthogonal to the pair of main surfaces, and an end portion including a pair of interposition surfaces disposed between the pair of main surfaces and the end surfaces; A method for producing a glass substrate of a cover glass for electronic equipment having:
An intervening surface forming step of forming the pair of interposing surfaces between the pair of main surfaces and the end surface of the glass substrate;
A mirroring process step for performing an etching process on the glass substrate so that the surface of the end part becomes a mirror surface;
The manufacturing method of the glass substrate of the cover glass for electronic devices characterized by including. The interposed surface forming step is a process using a mechanical processing means,
2. The electronic device cover according to claim 1, wherein in the mirroring process, an etching process is performed so that a damage layer that may be generated at the end portion is removed by the process using the mechanical processing unit. Manufacturing method of glass substrate of glass. The interposition surface forming step is an etching process,
The manufacturing method of the glass substrate of the cover glass for electronic devices of Claim 1 using the etching liquid from which a composition each differs in the said interposition surface formation process and the said mirror-finishing process process. In the intervening surface forming step, an etchant in which an acid having an acid dissociation constant larger than hydrofluoric acid is added as an additive to hydrofluoric acid or hydrofluoric acid is used.
In the mirror surface treatment step, an etching solution in which an acid having an acid dissociation constant larger than that of hydrofluoric acid is added as an additive to hydrofluoric acid is used.
4. The cover glass for an electronic device according to claim 3, wherein the concentration of the additive of the etching solution in the mirror finishing process is higher than the concentration of the additive of the etching solution in the interposition surface forming step. A method for producing a glass substrate. The mixing ratio of the substance amounts of hydrofluoric acid and the additive in the etching solution in the mirror finishing step is in the range of 10: 3 to 10:20 per 1 kg of the total amount of the etching solution. Item 5. A method for producing a glass substrate of a cover glass for electronic equipment according to Item 4. 6. The glass mirror substrate according to claim 1, wherein the glass substrate is immersed in an etching solution and the glass substrate is swung in parallel with a thickness direction of the glass substrate in the mirror finishing process. The manufacturing method of the glass substrate of the cover glass for electronic devices as described in a term. An opening forming step for forming an opening penetrating in the thickness direction of the glass substrate in the glass substrate using a mechanical processing means, which is performed before the mirror-finishing step;
Further including
7. The etching process is performed so that a damage layer that may be generated on an inner wall portion of the opening is removed by the opening forming process using the mechanical processing means in the mirror finishing process. The manufacturing method of the glass substrate of the cover glass for electronic devices of any one. A chemical strengthening step that is performed after the etching treatment step and performs chemical strengthening by ion exchange;
In the etching treatment step, an etching allowance is determined in advance so as to suppress breakage of the glass substrate in the chemical strengthening step due to a damaged layer that may be present on the inner wall portion of the opening. The manufacturing method of the glass substrate of the cover glass for electronic devices of Claim 7. The cover for electronic equipment according to any one of claims 1 to 8, wherein the etching process is performed in a state where a plurality of the glass substrates are laminated via a protective material having etching resistance. Manufacturing method of glass substrate of glass. A pair of main surfaces, an end surface disposed along a direction orthogonal to the pair of main surfaces, and an end portion including a pair of interposition surfaces disposed between the pair of main surfaces and the end surfaces; , A glass substrate for a cover glass for electronic equipment,
The glass substrate of the cover glass for electronic devices, wherein the interposition surface and the end surface are mirror surfaces. The glass substrate of the cover glass for an electronic device according to claim 10, wherein an isotropic surface roughness Ra in two directions orthogonal to each other of the end face is 1 µm or less. An opening is formed in the glass substrate,
The interposition surface is formed between the inner wall surface which is the surface of the inner wall part of the said opening, and said pair of main surfaces, The said interposition surface and the said inner wall surface are mirror surfaces. The glass substrate of the cover glass for electronic devices as described in 2.   The said glass substrate is aluminosilicate glass which can be chemically strengthened by ion exchange. The glass substrate of the cover glass for electronic devices of any one of Claims 10-12 characterized by the above-mentioned.

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