JP2015174777A - tempered glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tempered glass substrate having excellent strength even when a reinforcing layer is not formed on an end surface.SOLUTION: A tempered glass substrate 10 has: front and rear principal surfaces having an area where a compressive stress remains; and an end surface positioned between the front and rear principal surfaces and having an area where a compressive stress remains and an area where a tensile stress remains. The area where the tensile stress remains has first and second curved surface parts 18 and 18 having a predetermined curvature radius and has a straight part 19 having 1.7 mm or more of a curvature radius larger than the predetermined curvature radius between the first and second curved surface parts 18.

Description

  One embodiment of the present invention relates to a tempered glass substrate.

  A touch panel (so-called cover glass integrated touch panel) in which a sensor is formed on a cover glass substrate and the cover glass substrate and the sensor glass substrate are integrated has attracted attention. In the cover glass-integrated touch panel, the optical transparent adhesive and the sensor glass substrate in the touch panel are not necessary, so that the thickness and weight can be reduced.

  Cutting of tempered glass is more difficult than non-tempered glass. Therefore, in the manufacturing process of the cover glass substrate used for the conventional touch sensor, chemical strengthening is performed after cutting to the product shape. On the other hand, in the manufacturing process of the cover glass substrate used for the cover glass integrated type touch panel, from the viewpoint of improving production efficiency, the large glass substrate having a short side of 1000 mm or more is chemically strengthened and the large glass substrate is cut into a medium glass substrate. . After performing various processes such as forming a light-shielding film, a transparent conductive film, a metal wiring, an organic insulating layer, and a protective layer on the chemically strengthened medium-sized substrate, it is cut into a product shape (see, for example, Patent Document 1) .)

  Since the medium glass substrate is manufactured by cutting a chemically strengthened large glass substrate, the end surface is a substrate that is not strengthened. In the various processing steps described above, due to the necessity for alignment and the like, there is a problem that the end surface of the glass substrate inevitably hits a jig in the processing / film forming apparatus and the glass substrate is damaged.

JP 2011-197708 A

  An object of the present invention is to provide a tempered glass substrate having excellent strength even when a reinforced layer is not formed on the end face.

  The tempered glass substrate according to an aspect of the present invention includes a front and back main surface having a region where compressive stress remains, a region located between the front and back main surfaces, and a region where compressive stress remains and a region where tensile stress remains. A tempered glass substrate having an end surface, wherein the region where the tensile stress remains has a first curved surface portion and a second curved surface portion having a predetermined radius of curvature, and the first and second curved surface portions. Between the two, a straight portion having a radius of curvature larger than the predetermined curvature radius and 1.7 mm or more is provided.

  According to one embodiment of the present invention, a tempered glass substrate having excellent strength can be provided even if a tempering layer is not formed on the end face.

It is sectional drawing of the tempered glass substrate which concerns on embodiment of this invention. It is sectional drawing which showed typically the edge part of the tempered glass substrate of this embodiment. It is sectional drawing which showed typically the edge part of the tempered glass substrate of the comparative example of this embodiment. It is a graph showing the change of the impact strength by the difference in the end surface shape of a tempered glass substrate. It is the schematic diagram which showed an example of the strength measuring method of the tempered glass substrate which concerns on this embodiment. It is a graph showing the change of the flaw strength by the difference in the end surface shape of a tempered glass substrate. It is sectional drawing of the cover glass integrated touch panel using the tempered glass board | substrate 10 of this embodiment. It is a flowchart for demonstrating the manufacturing method of the tempered glass board | substrate which concerns on this embodiment.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

  First, a tempered glass substrate according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a tempered glass substrate 10 according to an embodiment of the present invention. In FIG. 1, the direction of the arrow indicates the direction of action of the residual stress, and the size of the arrow indicates the magnitude of the stress. As shown in FIG. 1, the tempered glass substrate 10 includes a surface layer 13 and a back surface layer 15, and an intermediate layer 17 provided between the surface layer 13 and the back surface layer 15, and an end surface of the tempered glass substrate 10. The intermediate layer 17 is exposed. Compressive stress remains on the front surface layer 13 and the back surface layer 15 by the following chemical strengthening method. Further, as a reaction, tensile stress remains in the intermediate layer 17.

  The tempered glass substrate 10 is produced by a chemical tempering method. As the glass for strengthening, alkali aluminosilicate glass or soda lime glass is used. In the chemical strengthening method, the front and back surfaces of glass are ion-exchanged, and ions having a small ion radius (for example, Li ions and Na ions) contained in the glass are replaced with ions having a large ion radius (for example, K ions). Thus, the front surface layer and the back surface layer in which the compressive stress remains are formed.

Further, the internal residual tensile stress CT (MPa) of the tempered glass substrate is usually measured by measuring the surface compressive stress CS (MPa) and the thickness DOL (μm) of the surface layer 13 and the back surface layer 15, and the measured value and strengthening. It can be calculated from the thickness t (μm) of the glass substrate using the following formula 1.
CT = (CS × DOL) / (t−2 × DOL) Equation 1

The maximum residual compressive stress CS, the internal residual tensile stress CT, and the thickness DOL of the surface layer 13 and the back surface layer 15 can be adjusted by the strengthening process conditions. In the case of the chemical strengthening method, since the glass is immersed in a treatment liquid (for example, KNO ₃ molten salt) for ion exchange, it can be adjusted by the concentration, temperature, immersion time, etc. of the treatment liquid.

  The thickness t (mm) of the tempered glass substrate 10 is preferably 0.1 to 1.1 mm. In the case of chemically strengthened glass, if the thickness t (mm) exceeds 1.1 mm, the mass of the substrate becomes large. On the other hand, when the thickness t (mm) is less than 0.1 mm, it is difficult to perform chemical strengthening treatment on the glass. The thickness t (mm) of the tempered glass substrate 10 is more preferably 0.3 to 0.7 mm.

  FIG. 2 is a cross-sectional view schematically showing an end portion of the tempered glass substrate 10 of the present embodiment. As shown in FIG. 2, the end surface of the tempered glass substrate 10 of this embodiment is processed into a shape in which a curved surface portion 18 and a linear portion 19 are combined. By combining the curved surface portion and the straight portion, the strength of the end surface can be improved even if the intermediate layer 17 where the tensile stress remains is a glass plate exposed on the end surface. In addition, the end surface of the tempered glass substrate 10 of this embodiment does not need to have a smooth straight portion in a strict sense, and an effect can be expected as a straight portion if the curvature radius R is suppressed to 1.7 mm or more. It does n’t matter.

  In other words, the end portion of the tempered glass substrate 10 of the present embodiment has a linear portion having a radius of curvature larger than the radius of curvature of the first and second curved surface portions between the first curved surface portion and the second curved surface portion. The curvature radius R is 1.7 mm or more. In this embodiment, since the end portion of the substrate has a straight portion, even if a positioning jig or the like contacts the end portion in the processing step, the impact is widely dispersed on the contact surface, so that high strength is maintained. Can do.

  FIG. 3 is a cross-sectional view schematically showing an end portion of the tempered glass substrate 20 of the comparative example of the present embodiment. As shown in FIG. 3, the end face of the tempered glass substrate 20 of the comparative example is processed into a shape including only the curved surface portion 18 without having a straight portion. In the case where the end portion has a shape including only the curved surface portion 18, the impact concentrates on only one point located on the outermost side, so that the strength of the tempered glass substrate is higher than the shape combining the curved surface portion and the straight portion. It will be lower.

  FIG. 4 is a graph showing the change in impact strength due to the difference in the end face shape of the tempered glass substrate. In FIG. 4, the upper and lower ends of the line segment in each sample represent the maximum value and the minimum value, and the wide region represents the region including the values of the first quartile to the third quartile. Yes. The vertical axis represents the breaking energy at which each sample was damaged. FIG. 5 is a schematic view showing an example of a method for measuring the strength of the tempered glass substrate according to the present embodiment. As shown in FIG. 5, a 5 mmφ carbide pin 51 was collided horizontally against the end face of the tempered glass substrate 10 fixed on the base 50, and the breaking energy at which cracking occurred was defined as impact strength.

  FIG. 6 is a graph showing a change in scratch strength due to a difference in the end face shape of the tempered glass substrate. A 10 mmφ PEEK material was collided horizontally at 180 mJ to the end face of the tempered glass substrate, and then the collided portion was placed downward, and a four-point bending test was performed. The method of collision of the PEEK material was the same as in the case of the impact strength measurement described above. Note that, for both measurements of impact strength and scratch strength, a tempered glass substrate sample having a thickness of 0.56 mm, a surface compressive stress of 700 MPa, and a compressive stress layer depth of 18 μm was used.

  The 4-point bending test was measured using a vertical 4-point bending test apparatus (Autograph AG-X, manufactured by Shimadzu Corporation). FIG. 10 is a schematic diagram of a vertical four-point bending test apparatus. Support part interval = 60 mm, load part interval = 20 mm, and crosshead (load part) speed = 1 mm / min. The end face whose fracture strength is measured in the test piece is the lower end face supported by the support portion.

  Then, with reference to FIG. 7, the cover glass integrated touch panel suitable for the use of the tempered glass board | substrate 10 of this embodiment is demonstrated. FIG. 7 is a cross-sectional view of a cover glass integrated touch panel using the tempered glass substrate 10 of the present embodiment. The cover glass integrated touch panel in FIG. 7 is a capacitive touch panel.

  As shown in FIG. 7, a light shielding film 31 such as a black matrix film is formed on the peripheral edge portion of the cover glass substrate 30 made of the tempered glass substrate 10. A pair of metal wirings 35 are formed on both sides of the light shielding film 31 so as not to be seen from the outside of the cover glass substrate 30 (the lower surface side of the cover glass substrate 30 in FIG. 7). In addition, the color of the light shielding film 31 is not particularly limited, and may be white, for example.

  Transparent conductive films 34 a and 34 b are formed at the center of the cover glass substrate 30. The transparent conductive film 34a extends in the x-axis direction in FIG. 7, and the transparent conductive film 34b extends in the y-axis direction in FIG. That is, the transparent conductive films 34a and 34b are extended so as to be orthogonal to each other. That is, in a plan view, the transparent conductive films 34a and 34b are formed in a lattice shape (not shown). In FIG. 7, only two transparent conductive films 34b are shown. Actually, however, a large number of transparent conductive films 34a and 34b are provided. Here, as shown in FIG. 7, the transparent conductive film 34a is formed so as to straddle between the metal wirings 35 on both sides.

As shown in FIG. 7, the organic insulating layer 36 is formed between the transparent conductive films 34a and 34b in order to insulate the transparent conductive films 34a and 34b from each other.
The protective layer 37 is formed on substantially the entire surface of the cover glass substrate 30 so as to cover the light shielding film 31, the transparent conductive films 34 a and 34 b, the metal wiring 35, and the organic insulating layer 36.

  By the way, the tempered glass substrate according to the present embodiment is obtained by chemically strengthening a large glass substrate having a short side of 1000 mm or more, and cutting it into a plurality of pieces. That is, the intermediate layer 17 having the internal residual tensile stress CT is exposed at the end face of the tempered glass substrate 10. Therefore, if the internal residual tensile stress CT becomes too large, cracks are likely to extend from the end face of the tempered glass substrate 10, and handling in the sensor forming process becomes difficult. Further, the larger the internal residual tensile stress CT, the more difficult the cutting itself. Therefore, the internal residual tensile stress CT is preferably 35 MPa or less. Further, the internal residual tensile stress CT is more preferably 30 MPa or less, still more preferably 20 MPa or less.

  Next, with reference to FIG. 8, the manufacturing method of the tempered glass substrate which concerns on this embodiment is demonstrated. FIG. 8 is a flowchart for explaining a method for manufacturing a tempered glass substrate according to this embodiment. In FIG. 8, in addition to the manufacturing flow (steps S1 to S3) of the tempered glass substrate indicated by the solid line, the subsequent flow (steps S4 to S8) indicated by the broken line is also described. FIG. 8 also shows the glass substrate size in each step together with the manufacturing flow. In addition, since the glass substrate size is a standard, it is not necessarily limited to implementation with a substrate of this size.

  First, as shown in FIG. 8, a large glass substrate having a short side whose end face is chamfered and whose short side is 1000 mm or more is chemically strengthened (step S1). As a large glass substrate, a so-called G6 size (long side: 1850 mm × short side: 1500 mm) having a rectangular shape can be used. Since the present invention is suitable for a large glass substrate having a short side of 1000 mm or more, a large glass substrate having a G5 size (long side 1200 mm × short side 1000 mm) may be used. Of course, as long as it is a large glass substrate having a short side of 1000 mm or more, it may be a size other than G5 and G6.

  Next, the chemically strengthened large glass substrate is cut and divided into a plurality of medium-sized glass substrates (step S2). As medium-sized glass substrates, so-called G1 size (long side 400 mm × short side 300 mm), G2 size (long side 470 mm × short side 370 mm), G3 size (long side 650 mm × short side 550 mm), G4 size (long side 880 mm × Short side of 680 mm). These sizes are due to device limitations in the sensor formation process. The medium size glass substrate is a rectangular glass substrate having a long side of less than 1000 mm, and may have a size other than the above as long as a plurality of cover glass integrated touch panels can be formed. In addition, you may test | inspect the end surface of the large sized glass substrate chemically strengthened before step S2.

  As a method for cutting a chemically strengthened large glass substrate, for example, a method of introducing a scribe line on a large glass substrate with a cutter wheel and breaking it, a method of cutting by irradiating a laser beam on the large glass substrate, etc. Can be used.

  Next, the end surface of the tempered glass substrate 10 is chamfered (step S3). In this chamfering process, the entire end surface of the tempered glass substrate 10 may be ground. The tempered glass substrate of this embodiment may be processed into a combination of a curved surface portion and a straight portion using C brushing or the like after polishing with a brush, or a combination of a plurality of grindstones to polish the curved surface portion. You may process into the shape which combined the linear part.

Below, the sensor formation process which forms a sensor in the manufactured tempered glass board | substrate 10 is demonstrated.
First, a light shielding film such as a black matrix film is printed on a tempered glass substrate (step S4).
Next, the wiring which consists of a transparent conductive film (for example, ITO film | membrane) is formed on a tempered glass board | substrate by sputtering method (step S5). Subsequently, metal wiring is formed on the tempered glass substrate by sputtering (step S6). Thus, the touch sensor is formed on the tempered glass substrate.

Thereafter, the tempered glass substrate on which the touch sensor is formed is cut to a product shape (step S7), and the end surface of the glass substrate of each product shape is chamfered (step S8).
The cover glass integrated touch panel is obtained as described above.

  In this embodiment, since the edge part of the tempered glass substrate is processed into a shape in which the curved surface part and the straight line part are combined, the substrate handling in the sensor forming step (steps S4 to S8) for forming the sensor on the tempered glass substrate. A tempered glass substrate having a high impact strength can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

10, 20, 30 Tempered glass substrate 13 Surface layer 15 Back layer 17 Intermediate layer 18 Curved portion 19 Linear portion 31 Light-shielding films 34a and 34b Transparent conductive film 35 Metal wiring 36 Organic insulating layer 37 Protective layer 50 Base 51 Carbide pin

Claims (1)

A tempered glass substrate having a front and back main surface having a region where compressive stress remains, and an end surface located between the front and back main surfaces and having a region where compressive stress remains and a region where tensile stress remains,
The region where the tensile stress remains has a first curved surface portion and a second curved surface portion having a predetermined radius of curvature,
A tempered glass substrate comprising a linear portion having a radius of curvature greater than the predetermined radius of curvature and not less than 1.7 mm between the first and second curved surface portions.

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