WO2014027546A1

WO2014027546A1 - Glass substrate and method for manufacturing glass substrate

Info

Publication number: WO2014027546A1
Application number: PCT/JP2013/069949
Authority: WO
Inventors: 正文伊藤; 祐介今里; 龍山口
Original assignee: 旭硝子株式会社
Priority date: 2012-08-13
Filing date: 2013-07-23
Publication date: 2014-02-20
Also published as: JP2015187042A; TW201410633A

Abstract

A glass substrate having a principal surface and an end face, wherein the level difference (Rk) of a core part of the end face, the arithmetic average inclination (RΔa) of the end face, and the cut level difference (Rδc) between a load length ratio of 35% and a load length ratio of 55% in the smoothed roughness curve of the end face are equal to or less than predetermined values.

Description

Glass substrate and method for manufacturing glass substrate

The present invention relates to a glass substrate and a method for producing the glass substrate.

In recent years, flat panel displays (FPD) such as liquid crystal displays (LCDs), plasma displays (PDPs), organic EL displays (OLEDs), field emission displays (FEDs) have become mainstream of image display devices.

The FPD has a configuration in which various wirings and elements are arranged on the main surface of a glass substrate. Since the manufacturing process of the glass substrate for FPD goes through processes such as polishing of the end face of the glass substrate, foreign matter such as minute glass pieces may adhere to the glass substrate, and the purpose of removing these deposits is A cleaning process has been applied. In recent years, a glass substrate is washed with a chemical solution having an etching property for the purpose of removing adhered substances that are firmly attached.
JP 2007-102843 A

However, if the glass substrate is washed with a chemical solution having an etching property, cracks of the glass substrate develop due to the etching. In particular, when cracks develop on the end face of the glass substrate, fine glass pieces (cullet and glass particles) may be generated from the end face.

Therefore, an object of the present embodiment is to provide a glass substrate that can suppress the generation of fine glass pieces after etching.

A glass substrate having a main surface and an end surface,
Provided is a glass substrate in which when the end face is etched with an etching amount of 0.5 μm or less, the level difference Rk of the core portion of the end face is 1.20 μm or less under the condition of a cutoff value of 0.8 mm. The

According to the present embodiment, it is possible to provide a glass substrate that can suppress dust generation after etching.

It is the schematic for demonstrating the example of the glass substrate of this embodiment. It is the schematic for demonstrating the mode of the progress of the crack by etching. It is the schematic for demonstrating a smoothing roughness curve and a load curve. It is an example of the laser micrograph of the glass substrate which concerns on this embodiment.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Main surface 3 End surface 4 Crack 10 Smoothing roughness curve 11 Load curve 12 Equivalent line

Hereinafter, the present embodiment will be described in more detail with reference to the drawings.

(Glass substrate)
The glass substrate of the present embodiment only needs to have an end surface. For example, a flat panel display such as a liquid crystal display (LCD), a plasma display (PDP), an organic EL display (OLED), a field emission display (FED), etc. Various glass substrates such as (FPD), touch panel, and solar cell are targeted.

Further, the glass base plate of the glass substrate of the present embodiment is produced by a method such as a float method, a fusion method, a redraw method, a press molding method, or a pulling method, but the present embodiment is not limited in this respect.

FIG. 1 shows a schematic diagram for explaining an example of the glass substrate of the present embodiment. The glass substrate 1 of this embodiment has the main surface 2 (front surface and back surface) normally comprised so that an image may be displayed, and the end surface 3 chamfered and finished. In FIG. 1, the end surface 3 is continuous with the main surface 2, but a structure in which a chamfered surface (not shown) is formed between the main surface 2 and the end surface 3 may be used.

Conventionally, various polishing treatments have been performed on the end surface 3 of the glass substrate for the purpose of increasing the strength of the glass substrate. Since foreign matters such as fine glass pieces remain attached to the main surface 2 and the end surface 3 (hereinafter also referred to as the glass substrate surface) of the glass substrate after the polishing treatment, a cleaning process is performed for the purpose of removing foreign matters. Has been applied.

As a cleaning process, scrub cleaning that removes foreign matters by pressing a brush roller or sponge roller that rotates with a motor against the glass substrate surface while supplying detergent or pure water to the glass substrate surface has been generally performed. . However, the scrub cleaning may not be able to remove the foreign matter firmly adhered to the glass substrate surface. Therefore, in recent years, foreign substances may be removed by cleaning the glass substrate with a chemical solution having etching properties.

As the chemical solution having etching properties in cleaning, an etching solution mainly containing any one of hydrofluoric acid, silicic hydrofluoric acid, ammonium fluoride, and sodium fluoride is usually used. Further, the etching solution may be a mixed acid solution (acidic solution) containing other acids such as hydrochloric acid, nitric acid, sulfuric acid, or an alkaline solution from the viewpoint of storage stability. good. In the present specification, the main component refers to a component that is contained most in the etching solution.

When a glass substrate is cleaned using the above-mentioned chemical solution having etching properties, the glass substrate is about 0.01 to 0.1 μm (maximum of 0.5 μm or less depending on the cleaning time and the type of the chemical solution). ) Wet etching. However, when the glass substrate is washed with a chemical solution having an etching property, a crack on the surface of the glass substrate develops due to the etching. In particular, on the end surface of the glass substrate, there are many scratches due to the polishing treatment from the main surface of the glass substrate, so that a small glass piece may be separated from the end surface and generate dust when cracks develop. .

FIG. 2 is a schematic diagram for explaining the progress of cracks caused by etching. More specifically, FIG. 2 is an enlarged view around the end face 3 of the glass substrate 1 of FIG. 2A is an example of the glass substrate 1 before etching, and FIG. 2B is an example of the glass substrate 1 after etching. Further, in FIG. 2B, a schematic diagram of the end face 3 before etching shown in FIG.

2A, the end surface 3 of the glass substrate 1 has micro-order cracks, scratches, and defects (collectively referred to as cracks 4) due to the polishing process. When tensile stress is applied to the glass substrate 1 in FIG. 2A, stress concentration occurs in the crack 4, and the crack 4 progresses and the glass substrate 1 is broken.

When the glass substrate 1 shown in FIG. 2 (a) is etched several μm isotropically from the surface of the end face 3 by, for example, an etching chemical in the cleaning liquid, as shown in FIG. 2 (b), Crack 4 expands. At this time, for example, in the region A, dusting of a small glass piece may occur due to an adjacent crack.

In this embodiment, when the end surface of the glass substrate is washed with a chemical solution having an etching property, the end surface of the glass substrate is preliminarily polished so that the end surface of the glass substrate has a predetermined surface property. It was found that it can be suppressed. Specifically, in this embodiment, the glass substrate after being etched with an etching amount of 0.5 μm or less using an etching solution mainly containing hydrofluoric acid, silicic hydrofluoric acid, ammonium fluoride, or sodium fluoride. The generation of cracks is suppressed by polishing the end surface of the glass substrate in advance so that the end surface has a predetermined surface property. In addition, the amount by which the end surface of the glass substrate is etched in the cleaning process using the chemical solution having an etching property is 0.5 μm or less at the maximum.

In another embodiment of the present embodiment, regarding the condition of the surface property of the end surface of the glass substrate before etching, which can suppress dust generation even when the end surface of the glass substrate is etched by a chemical solution having etching properties. I also found. Therefore, by polishing the end surface of the glass substrate in advance so as to have a predetermined surface property, even when the end surface is etched by a chemical solution having etching properties in the subsequent process, Generation of dust can be suppressed.

The polishing grindstone in the end surface polishing treatment usually has polishing abrasive grains and a bond for fixing the abrasive grains. In the present embodiment, a soft grindstone having a diamond grain having a small grain size with an average grain size of 40 μm or less is used, or cubic boron nitride (CBN), silicon carbide (SiC), or alumina is used as the abrasive grain. Using the polishing wheel having (Al ₂ O ₃ ), the end surface of the glass substrate is polished by applying the side surface of the polishing wheel to the end surface of the glass substrate under the polishing conditions shown as an example below. Thus, it has been found that even when the end surface is etched by cleaning with a chemical solution having etching properties, the generation of dust on the minute glass pieces is suppressed. As polishing conditions, for example, the rotational speed is 3000 to 10000 rpm, and the relative feed speed between the glass substrate and the polishing grindstone is 3 to 30 m / min.

The polishing of the end surface can be performed using a known glass substrate end surface polishing apparatus (glass substrate end surface grinding apparatus). The glass substrate end surface polishing apparatus is usually provided with a cylindrical polishing grindstone, and the polishing grindstone has a groove formed in the side surface along the circumferential direction. The end face can be polished by pressing the end face against the groove while rotating the polishing grindstone. At this time, the end face is polished according to the shape of the groove. The cross-sectional shape of the groove usually has a shape that gradually widens from the bottom side of the groove to the surface of the grinding wheel, but the size and detailed shape of the groove depends on the thickness of the glass substrate and the desired end face shape. Accordingly, those skilled in the art can select as appropriate.

The glass substrate end surface polishing apparatus may have a plurality of end surface polishing units such as a primary end surface polishing unit and a secondary end surface polishing unit from the upstream side in the glass substrate processing step. In the upstream end face polishing portion in the glass substrate processing step, a polishing grindstone having a larger average particle size (a larger grindstone count) than that used in the downstream end face polishing portion is usually used. A method of finishing the polished surface to a smooth surface is employed. Also in the present embodiment, within the above-described range of the average particle diameter, the polishing grindstone used in the upstream end face polishing section has a larger average particle diameter than the polishing grindstone used in the downstream end face polishing section. It is preferable.

In addition, the above-described polishing method suppresses the generation of minute glass pieces generated during glass polishing; suppresses the attachment of minute glass pieces to the glass substrate; suppresses stress concentration, and destroys the glass substrate. The pressure when the positioning pins contact when the glass substrate is transported is dispersed, damage to the glass substrate is reduced, and dust generation from the damaged portion is suppressed; Also has the effect of.

(Surface properties)
Next, the preferable surface property about an end surface which can suppress generation | occurrence | production of the dust of a minute glass piece is demonstrated.

First, how to obtain a cross-sectional curve and a smoothed roughness curve used for obtaining each surface property described later will be briefly described. In the present embodiment, the cutoff value λc (reference length Lr) is 0.025 mm, 0.08 mm, 0.25 mm, and 0.8 mm, and the evaluation length Ln is five times the cutoff value λc. It was the above length.

The stylus of the surface roughness measuring device was moved on the end surface of the glass substrate, and the locus of the center of the stylus tip was measured to obtain a measurement curve. The obtained measurement curve was A / D converted to obtain a measurement cross section curve. A low-pass filter having a predetermined cut-off value λc was applied to the obtained measurement cross-sectional curve to obtain a cross-sectional curve from which undulation was removed.

Also, a smoothing roughness curve was obtained by subjecting the cross-sectional curve obtained above to the following filter processing. The cross-sectional curve was filtered with a phase compensation filter, and the first average line was calculated. A portion below the first average line was removed to calculate a second average line, and the second average line was filtered with a phase compensation filter to calculate a third average line. Finally, a smoothed roughness curve was obtained by subtracting the third average line from the cross-sectional curve.

FIG. 3 is a schematic diagram for explaining the smoothed roughness curve 10 and the load curve 11. The horizontal axis in the smoothed roughness curve 10 in FIG. 3 is the coordinate in the direction of the third average line, and the vertical axis is the coordinate in the depth direction of the end face. The load curve 11 is a plot of the value of the load length rate tp on the horizontal axis and the height of the smoothed roughness curve 10 on the vertical axis. The load length ratio tp means that the smoothed roughness curve 10 is extracted by the reference length Ln in the horizontal axis direction, and the smoothed roughness curve 10 is extracted from the upper end to the lower end along a cutting line parallel to the horizontal axis. The sum of the cutting lengths at each cutting line obtained when cutting is expressed as a ratio in percentage to the reference length Ln. In addition, the reference length Ln is usually set to 5 times or more of the aforementioned cut-off value.

In the present embodiment, the level difference Rk, the arithmetic average slope RΔa, and the cutting level difference Rδc of the core portion were obtained by the method described below using a smoothed roughness curve and / or a load curve.

[Level difference Rk in the core]
In the load curve shown in FIG. 3, an equivalent straight line 12 having a length of 40% is drawn based on JIS B0671 (2002). The intersection between this equivalent line and 0% vertical line is the upper level of the core part, and the intersection of the equivalent line and 100% vertical line is the lower level of the core part, and the difference between the upper level and the lower level is obtained. Thus, the level difference Rk of the core portion was obtained.

In the present embodiment, when the end surface of the glass substrate is etched with an etching amount of 0.5 μm or less, the level difference Rk of the core part may be 1.20 μm or less under the condition of the cutoff value λc = 0.8 mm. Preferably, it is 1.00 μm or less, more preferably 0.48 μm or less, more preferably 0.30 μm or less under the condition of a cutoff value λc = 0.025 mm.

In the present embodiment, the level difference Rk of the core part before etching the end face of the glass substrate is preferably 1.00 μm or less under the condition of the cutoff value λc = 0.8 mm, and 0.70 μm or less. More preferably, it is preferably 0.40 μm or less, more preferably 0.13 μm or less under the condition of a cutoff value λc = 0.025 mm.

[Arithmetic mean slope RΔa]
The arithmetic average gradient at the reference length Lr of the smoothed roughness curve was obtained and used as the arithmetic average gradient RΔa of this embodiment.

In this embodiment, when the end surface of the glass substrate is etched with an etching amount of 0.5 μm or less, the arithmetic average gradient RΔa is preferably 0.13 or less under the condition of the cutoff value λc = 0.025 mm.

Moreover, in this embodiment, it is preferable that arithmetic mean inclination R (DELTA) a before etching the end surface of a glass substrate will be 0.10 or less on condition of cutoff value (lambda) c = 0.8mm, and will be 0.07 or less. Is more preferable, and is preferably 0.12 or less, more preferably 0.07 or less under the condition of a cutoff value λc = 0.025 mm.

[Cutting level difference Rδc]
The cutting level difference Rδc in this embodiment was defined as a cutting level difference between a load length ratio of 35% and a load length ratio of 55% in the smoothed roughness curve.

In the present embodiment, when the end surface of the glass substrate is etched with an etching amount of 0.5 μm or less, the cutting level difference Rδc is preferably 0.25 μm or less under the condition of the cutoff value λc = 0.8 mm. More preferably, it is 0.19 μm or less, preferably 0.09 μm or less, more preferably 0.06 μm or less under the condition of a cutoff value λc = 0.025 mm.

In the present embodiment, the cutting level difference Rδc before etching the end face of the glass substrate is preferably 0.20 μm or less and 0.14 μm or less under the condition of the cutoff value λc = 0.8 mm. Is more preferably 0.08 μm or less, and more preferably 0.03 μm or less under the condition of a cutoff value λc = 0.025 mm.

(Example)
Next, an embodiment in which the effect of having a predetermined surface property on the end surface of the glass substrate when the end surface of the glass substrate is etched with an etching amount of 0.5 μm or less will be described.

In this embodiment, the end surface of the glass substrate was polished using a known glass substrate end surface polishing apparatus provided with the following polishing grindstone. In this example, polishing was performed using a soft grindstone having diamond abrasive grains having an average particle diameter of 40 μm or less, or a grindstone having silicon carbide as the abrasive grains. Further, as a comparative example, polishing was performed using a polishing grindstone having diamond abrasive grains having an average particle diameter of about 50 μm.

For the polished glass substrate of each example or comparative example, the level difference Rk, arithmetic average slope RΔa, and cutting level difference Rδc of the core portion were determined by the method described above. Thereafter, the polished glass substrate was immersed in an etching solution containing a predetermined concentration of hydrofluoric acid for a predetermined time to be etched by about 0.1 μm. The surface properties described above were also obtained for the glass substrate after etching.

Table 1 and Table 2 show the parameters of each surface property in the glass substrate obtained in each Example or Comparative Example.

Table 1 shows the parameters of the surface properties when the cutoff value λc is 0.025 mm, and Table 2 shows the parameters of the surface properties when the cutoff value λc is 0.8 mm. In addition, the speed in Table 1 and Table 2 refers to the relative feed speed between the glass substrate and the polishing grindstone during polishing.

(Evaluation)
Evaluation of the glass substrate obtained by each Example and the comparative example was performed by surface observation of the glass substrate end surface using a laser microscope.

FIG. 4 shows an example of a laser microscope photograph of the glass substrate according to the present embodiment. 4 (a) is a laser micrograph after etching on the end face of the glass substrate of Example 3 in Table 1, and FIG. 4 (b) is on the end face of the glass substrate of Comparative Example 1 in Table 1. It is a laser micrograph after etching.

The photograph shown in FIG. 4 (a) has a larger white area than the photograph shown in FIG. 4 (b). The white part is because the light reaching the glass substrate end face from the laser microscope is reflected and displayed, which indicates that the glass substrate end face is flat. On the other hand, the black portion is because the light reaching the glass substrate end surface from the laser microscope is scattered and displayed, which indicates that the glass substrate end surface is not flat. Therefore, it can be seen that the end face of the glass substrate is flat even after etching. That is, the glass substrate of this embodiment can suppress dust generation even when it is etched. On the other hand, the glass substrate of the comparative example shown in FIG. 4B is not flat and has large irregularities after etching. Therefore, when the glass substrate of the comparative example is etched, dust generation may occur, and in the subsequent process, there is a high possibility that the glass substrate will be broken due to contact with other structures.

In addition, the glass substrates obtained in the respective examples and comparative examples were evaluated by measuring the occupancy ratio at the end face of the glass substrate.

Occupancy is the area ratio of glass particles adhering to the pressure-sensitive adhesive tape pressed against the glass end face (ratio of glass particle area per unit area of the pressure-sensitive adhesive tape = glass particle area / unit area of the pressure-sensitive adhesive tape × 100%).

In this embodiment, the occupation ratio is measured by pressing the glass end face against the adhesive tape, then observing the adhesive tape surface with a laser microscope and storing the image, and binarizing the area ratio of the glass particles. It went by.

In addition, as a criterion for occupancy rate,
A: Occupancy rate is less than 4% B: Occupancy rate is 4% or more and less than 8% C: Occupancy rate is 8% or more.

A glass substrate with an end face occupation ratio of A or B has few glass particles adhering to the end face. In other words, it can be said that the glass substrate has a flat end surface and can suppress the generation of dust from a minute glass piece.

As described above, the glass substrate of the present embodiment is a glass substrate having a main surface and an end surface, and when etched with an etching amount of 0.5 μm or less, the surface property of the end surface is a predetermined value or less. By being, generation | occurrence | production of dust can be suppressed.

(Glass substrate manufacturing method)
An embodiment for inspecting a glass substrate will be described as one step of the method for producing the glass substrate.

First, a plurality of FPD glass substrates on which a main surface and end surfaces are formed in advance are prepared. As described above, a plurality of (for example, 50) glass substrates can be obtained through a cutting process and an end face forming process using a glass base plate manufactured by, for example, a float process. The end surfaces of the prepared plurality of glass substrates are polished by a polishing apparatus. Polishing is performed using, for example, a soft grindstone having diamond abrasive grains having an average particle diameter of 40 μm or less or a grindstone having silicon carbide or alumina as the abrasive grains. At a relative feed speed of 6 to 12 m / min. Next, wet etching is performed on the end surfaces of one or more glass substrates among the polished glass substrates with an etching amount of 0.5 μm or less. About the end surface of the etched glass substrate, the surface property, for example, the level difference Rk of the core part is measured. If the measurement result regarding the measured surface texture is equal to or less than a predetermined value, it is determined that the remaining glass substrates of the plurality of glass substrates are non-defective products.

According to the method for manufacturing a glass substrate of the present embodiment, when the glass substrate has a main surface and an end surface and is etched with an etching amount of 0.5 μm or less, whether or not the surface property of the end surface is a predetermined value or less. The process of determining is included. Except for the glass substrate determined to be less than or equal to a predetermined value, the remaining glass substrate, even when washed with a chemical solution having etching properties in the subsequent cleaning step, because the surface properties of the end face is less than or equal to a predetermined value, A non-defective glass substrate, that is, a glass substrate that generates little dust or does not affect subsequent processes.

Also, as a modification of the glass substrate manufacturing method according to another embodiment, the glass substrate may be determined by measuring the surface properties of the end surface of the glass substrate before etching in the same manner. Specifically, first, a plurality of FPD glass substrates on which a main surface and end surfaces are formed in advance are prepared. As described above, a plurality of (for example, 50) glass substrates can be obtained through a cutting process and an end face forming process using a glass base plate manufactured by, for example, a float process. The end surfaces of the prepared plurality of glass substrates are polished by a polishing apparatus. Polishing is performed using, for example, a soft grindstone having diamond abrasive grains having an average particle diameter of 40 μm or less or a grindstone having silicon carbide or alumina as the abrasive grains. At a relative feed speed of 6 to 12 m / min. Next, with respect to the end surface of the polished glass substrate, the surface property, for example, the level difference Rk of the core part is measured. If the measurement result regarding the measured surface texture is equal to or less than a predetermined value, it is determined that all of the plurality of glass substrates are non-defective products.

According to the glass substrate manufacturing method of the present embodiment, the glass substrate has a main surface and an end surface, and includes a step of determining whether or not the surface property of the end surface is equal to or less than a predetermined value before etching. All glass substrates, including glass substrates determined to be a predetermined value or less, even when washed with a chemical solution having an etching property in a subsequent cleaning step, because the surface properties of the end face are less than a predetermined value, A non-defective glass substrate, that is, a glass substrate that generates little dust or does not affect subsequent processes.

This application claims priority based on Japanese Patent Application No. 2012-179620 filed with the Japan Patent Office on August 13, 2012. The entire contents of Japanese Patent Application No. 2012-179620 are incorporated herein by reference. To do.

Claims

A glass substrate having a main surface and an end surface,
A glass substrate in which, when the end face is etched with an etching amount of 0.5 μm or less, the level difference Rk of the core portion of the end face is 1.20 μm or less under the condition of a cutoff value of 0.8 mm.
A glass substrate having a main surface and an end surface,
A glass substrate in which, when the end face is etched with an etching amount of 0.5 μm or less, the arithmetic average slope RΔa of the end face is 0.13 or less under the condition of a cutoff value of 0.025 mm.
A glass substrate having a main surface and an end surface,
When the end face is etched with an etching amount of 0.5 μm or less, a cutting level difference Rδc between a load length ratio of 35% and a load length ratio of 55% of the smoothed roughness curve of the end face is: A glass substrate that is 0.25 μm or less under the condition of a cutoff value of 0.8 mm.
A glass substrate having a main surface and an end surface,
The glass substrate whose level difference Rk of the core part of the said end surface is 1.00 micrometer or less on condition of the cutoff value of 0.8 mm.
A glass substrate having a main surface and an end surface,
The glass substrate in which the arithmetic average slope RΔa of the end face is 0.10 or less under the condition of a cutoff value of 0.8 mm.
A glass substrate having a main surface and an end surface,
The cutting level difference Rδc between the load length ratio of 35% and the load length ratio of 55% of the smoothed roughness curve of the end face is 0.20 μm or less under the condition of a cutoff value of 0.8 mm. There is a glass substrate.
A method for producing a glass substrate having a main surface and an end surface,
Preparing a plurality of glass substrates having a main surface and an end surface;
Polishing the end faces of the plurality of glass substrates;
Etching the end face of one or more glass substrates among the polished glass substrates with an etching amount of 0.5 μm or less;
Measuring the surface properties of the end face after etching;
Determining whether the measurement result is a predetermined value or less;
A method for producing a glass substrate, comprising:
A method for producing a glass substrate having a main surface and an end surface,
Preparing a glass substrate having a main surface and an end surface;
Polishing the end face of the glass substrate;
Measuring the surface properties of the end face;
Determining whether the measurement result is a predetermined value or less;
A method for producing a glass substrate, comprising: