JP2001130920A - Glass substrate for display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glass substrate for a display, preventing pattern discrepancy in lamination by suppressing substrate deformation occurring in cutting. SOLUTION: This glass substrate is an approximately rectangular plane having >=300 mm short side, <=3,000 mm long side and >=0.3 mm and <=6 mm thickness and has <=1 Mpa deviation stress in the substrate plane, due to residual strain in the glass substrate, in all positions in the substrate and measured in the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a glass substrate for a display, and more particularly, to a liquid crystal display (TFT-type).
LCD, STN-LCD), plasma display (P
DP), plasma assisted liquid crystal display (PAL)
C), electroluminescent display (E
L), Field Emission Display (FE)
D) and the like, and relates to a glass substrate for a flat panel display (a flat display).

[0002] In flat panel displays, usually 2
Glass substrates are used, and these glass substrates are TF
In a T liquid crystal display, it is called an array side substrate and a color filter side substrate, and in a plasma display, it is called a front plate and a back plate. The present invention relates to these glass substrates.

[0003]

2. Description of the Related Art In a flat panel display, usually 2
Two glass substrates are used, and a light emitting mechanism and a light transmission control mechanism are formed between these two glass substrates. The glass used as the glass substrate is typically a non-alkali borosilicate glass (for example, manufactured by Asahi Glass Co., Ltd. [trade name: AN635,
AN100 etc.), soda lime glass (for example, Asahi Glass Co., Ltd. [trade name: A
S]) and the like, high strain point glass (for example, [trade name: PD200] manufactured by Asahi Glass Co., Ltd.) is used in the plasma display.

[0004] These glass substrates are manufactured by a method such as a float method, a fusion method, and a slit down draw method. The glass ribbon formed into a certain thickness by these manufacturing methods is cut into a surface shape having a predetermined dimension and supplied as a glass substrate. Some glass substrates are subjected to annealing (annealing) in order to control the heat shrinkage (compaction) to a constant value after molding.

[0005] In the production of a flat panel display using the above glass substrate, there are cases where multiple panels are formed in order to increase production efficiency. That is, a plurality of panel patterns such as two, four, six, and eight panels are formed in one glass substrate, and a panel with a plurality of panels is manufactured at the same time. The panel on which the pattern of the plurality of surfaces is formed is cut into a size corresponding to one surface before or after the two substrates are bonded to each other to have the dimensions of a product panel.

[0006]

In the above-mentioned multiple substrate, when a glass substrate has a strain in a plane direction, the glass substrate is deformed as shown in FIG. 1 by cutting. Here, arrow 2 in the figure indicates the direction of the residual stress. That is, FIG.
FIGS. 3A and 3B are schematic diagrams illustrating deformation due to cutting of the glass substrate 1, wherein FIG. 3A is a schematic diagram illustrating a state of residual stress of the glass substrate 1 before cutting, and FIG. Is a schematic diagram showing a shape after cutting, FIG. 3C is a schematic diagram illustrating a state of residual stress of the glass substrate 1 before cutting, and FIG.
FIG. 3C is a schematic view showing the shape after cutting the glass substrate of FIG.

When such deformation occurs, a deviation occurs in the formed pattern when two glass substrates are bonded to each other, but such deviation of the pattern causes a problem in quality. For example, in a manufacturing process of a TFT liquid crystal display, display unevenness due to a decrease in luminance occurs due to a pattern shift of several μm to several tens of μm.

[0008] The deformation of the glass substrate due to the above cutting also depends on the size of the glass substrate, and is more remarkable for a glass substrate having a larger planar dimension. That is, when the strain is uniformly distributed in the plane of the glass substrate, the residual stress increases as the plane size of the glass substrate increases. Further, when the glass substrate is deformed in a certain shape (similar shape), the larger the planar dimension of the glass substrate, the larger the amount of deformation in the peripheral portion of the substrate. In particular, deformation of the glass substrate due to cutting is a problem that occurs significantly in a rectangular glass substrate having a short side of 300 mm or more.

Here, the relationship between the distortion of the glass substrate and the warpage of the glass substrate will be described. The glass substrate is internally distorted due to heat history during cooling, and generates residual stress. Physically strengthened glass is known as a glass utilizing this phenomenon. That is, a method of forming a compressive stress layer on the glass surface by blowing air or the like onto the surface when cooling the glass and forcibly cooling the surface.

[0010] Distortion of glass occurs not only in the stress distribution in the cross-sectional direction of glass known as tempered glass but also in the plane direction. That is, when the temperature of the peripheral part is lower than that of the central part of the glass substrate during cooling of the glass substrate, a stress in the compression direction is generated along the periphery in the surface of the glass substrate. Conversely, when the temperature of the peripheral part is higher than that of the central part during cooling of the glass substrate, a tensile stress is generated along the periphery in the surface of the glass substrate.

FIG. 1 schematically shows the deformation of a substrate that occurs when a substrate in which stress due to strain remains around the substrate is cut. In the case of a substrate having a compressive stress applied to its periphery, the substrate is deformed inward because the compression strain is released and stretched after cutting (the state shown in FIG. 1B). In a substrate having a tensile stress applied to its surroundings, the substrate is deformed outward because the tensile strain is released and shrunk after cutting (the state shown in FIG. 1D).

As described above, if there is a distortion in the glass substrate, the substrate is deformed at the time of cutting. Therefore,
There has been a demand for a glass substrate having no distortion or a glass substrate having a distortion equal to or less than a certain value that does not deform the substrate.

[0013]

According to the present invention, the short side is 300.
mm, a glass substrate having a substantially rectangular surface shape having a long side of 3000 mm or less and a plate thickness of 0.3 mm or more and 6 mm or less, when measured in the plate thickness direction due to residual strain in the glass substrate. The present invention provides a display glass substrate having a deviation stress in the substrate plane of 1 MPa or less at all positions in the substrate. Such a glass substrate having a small deviation stress due to residual strain in the substrate does not cause deformation of the substrate at the time of cutting, or has a level almost negligible, and is desirable as a glass substrate for a display. Note that the glass substrate of the present invention is substantially rectangular, and includes a glass substrate in which peripheral corners are cut off (corner cut).

Further, the present invention provides a method for manufacturing a semiconductor device, comprising:
A glass substrate of 6 mm or less, which is cut into a substantially rectangular surface shape having a short side of 300 mm or more and a long side of 3000 mm or less, then subjected to heat treatment of heating and slow cooling, and due to residual strain in the glass substrate. The deviation stress in the substrate plane measured in the thickness direction is 1 MPa at all positions in the substrate.
The following glass substrate for a display is provided. Deviation stress due to residual strain in the substrate is large, even if the glass substrate is not desirable as a display glass substrate,
By performing such processing, the deviation stress due to the residual strain in the substrate can be reduced.

Further, according to the present invention, the sheet thickness is 0.3 mm or more,
A glass substrate of 6 mm or less, which is cut into a substantially rectangular surface shape with a short side of 300 mm or more and a long side of 3000 mm or less, is not subjected to heat treatment of heating / gradual cooling, and has residual strain in the glass substrate. The deviation stress in the substrate plane when measured in the thickness direction is 1MP at all positions in the substrate.
a glass substrate for a display which is equal to or less than a. It is most desirable if a glass substrate having a small deviation stress due to the residual strain in the substrate can be manufactured by optimizing the manufacturing conditions at the time of molding the glass substrate, since heat treatment of heating and slow cooling is unnecessary.

Further, according to the present invention, the short side is 500 mm or more,
Provided is a display glass substrate having a thickness of 1.1 mm or less and used for a liquid crystal display panel. A glass substrate having the above thickness is usually used for the liquid crystal display panel. With such a thickness, distortion is unlikely to occur in the forming process, and heat treatment such as heating and slow cooling is unnecessary.

Further, according to the present invention, the short side is at least 500 mm,
Provided is a display glass substrate having a thickness of 1.5 mm or more and used for a plasma display panel. Generally, a glass substrate having the above-mentioned thickness is used for the plasma display panel. With such a thickness, heating and
Slow cooling heat treatment is effective in reducing residual strain in the substrate.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, strain and stress in a glass substrate are measured by the following methods. The distortion in the glass substrate can be estimated by measuring the optical birefringence, that is, by measuring the optical path difference between the orthogonal linearly polarized waves. Assuming that the optical path difference is R (nm), the deviation stress F generated due to the strain
(MPa) is expressed as F = R / CL. Here, L is the distance (c
m), and C is a proportionality constant determined by glass and is called a photoelastic constant, and is usually 20 to 40 (nm / cm) / (M
Pa).

When there is no strain in the glass, that is, when there is no stress or isotropic stress, the two orthogonal linearly polarized waves pass through the glass at the same speed.
If there is a strain in the glass surface, the polarized wave will pass faster in the direction of compressive stress and will slowly pass in the direction of tensile stress. That is, an optical path difference occurs between two orthogonal linearly polarized waves. By taking an optical path perpendicular to the plane of the substrate and measuring the azimuth at which the optical path difference is maximized and its magnitude, the directionality and magnitude of the strain in the glass substrate can be measured. This value is defined as the deviation stress.

The deviation stress F is a stress value measured from the optical path difference of the polarized wave, and is an index indicating the anisotropy of the stress existing in the plane. The deviation stress F is an average value of the distance that the polarized light has passed in the glass substrate, and is determined as the direction in which the stress difference becomes maximum and the stress difference in any two axes orthogonal to each other in a plane perpendicular to the optical path. In the case where a compressive stress remains in a certain direction (for example, the X direction) in the surface of the glass substrate, and in the case where a tensile stress having the same magnitude remains in a direction perpendicular thereto (the Y direction), the deviation stress is measured. Have the same result.
Further, if the same amount of compressive or tensile stress remains in two orthogonal axes directions (X direction and Y direction), the deviation stress becomes zero.

The measurement of glass strain using a linearly polarized wave is as follows.
The Senarmont method and the like are known, and an optical path difference of several tens nm can be detected. Conventionally, strain measurement of glass mainly targets a stress of several tens MPa remaining in tempered glass or the like, and the Senarmont method has sufficient analysis accuracy for such strain measurement.

However, the stress remaining on the glass substrate for a flat panel display in the plane direction is 0.1 MPa.
It is a size of a to 5 MPa and cannot be sufficiently detected by the conventional measuring method. Therefore, the present inventors used an ABR-10A birefringence meter manufactured by Uniopt Corporation as a strain detection device. The ABR-10A birefringence measuring device is a device that measures a birefringent optical path difference and a principal axis direction by irradiating a transverse Zeeman laser beam and detecting a phase difference between orthogonal linearly polarized waves. The resolution has an optical path difference of 0.01 nm and a main axis azimuth of 0.1 degree.

The residual strain of the glass substrate is generated depending on the temperature distribution in the slow cooling after forming the glass ribbon. That is, a compressive stress is formed in a portion that has been cooled earlier, and a tensile stress is formed in a portion that is cooled later. This is well known as the principle of physical strengthening or air cooling of glass. In the tempered glass, a compression stress layer is formed on the surface by rapidly cooling the glass surface.

Although the tempered glass utilizes the stress distribution in the thickness direction of the glass, the glass also has a stress distribution in the plane direction. The present inventors have found that a substrate in which the stress distribution in the plane direction of the glass substrate causes deformation at the time of glass cutting, and a substrate whose deformation is suppressed by controlling the residual stress due to the strain to a certain value or less. Gained,
I found

The stress distribution in the plane direction of the glass substrate is generated by the temperature distribution at the time of cooling after forming the glass ribbon. Generally, a glass substrate for a flat panel display is continuously manufactured by a manufacturing method such as a float method, a fusion method, and a slit down draw method.
Therefore, it is governed by the temperature distribution at the time of cooling, particularly the temperature distribution in the plate width direction perpendicular to the flow of the glass ribbon at the time of manufacturing.

FIG. 2 schematically shows the temperature distribution in the width direction of the glass ribbon and the stress distribution of the cut glass substrate 1. Here, arrow 2 in the figure indicates the direction of the residual stress. When the temperature of the peripheral portion is lower than that of the central portion, that is, in the state of (a) in the figure, the residual stress of the compression enters the peripheral portion and becomes the state of (b) in the diagram, and the temperature of the peripheral portion is lower than that of the central portion. When it is high, that is, when it is in the state of (c) in the figure, the residual stress of the tensile force enters the peripheral portion, and the state of (d) is obtained.

The present inventors have verified the relationship between the temperature distribution in the width direction of the glass ribbon and the residual stress of the glass substrate, and have determined the conditions under which the residual stress of the glass substrate becomes extremely small by manipulating the temperature distribution. I found it.

Further, in order to reduce the residual stress of the glass substrate, in the glass substrate manufacturing process, an annealing process of a substantially rectangular glass substrate cut into a predetermined size, that is, a heat treatment process of reheating and slow cooling is performed. Is valid. Thus, when performing an annealing process on a glass substrate,
The glass substrate may be heated to a temperature near the gradual cooling point temperature and then gradually cooled to a temperature near the strain point temperature.

In general, many plasma display panels are 50-inch (about 1270 mm diagonally) or larger, and the size and thickness of the display glass substrate used are large. Therefore, distortion is likely to occur in the sheet glass forming process, and there is an effect of performing an annealing treatment after forming the glass substrate. However, as described above, by controlling the temperature distribution in the annealing process at the time of forming the glass substrate, the residual stress of the glass substrate can be extremely reduced, and the annealing process after forming the glass substrate can be eliminated.

On the other hand, the liquid crystal display panel is strongly required to be reduced in weight, so that the thickness of the display glass substrate used is generally small. Therefore, distortion is unlikely to occur during the forming process, and there is little need to perform an annealing treatment after forming the glass substrate.

From the viewpoint of production cost, it is preferable that the annealing treatment after the formation of the glass substrate is not carried out, since this leads to an increase in cost. When the annealing treatment is not performed after the glass substrate is formed, a horizontal drawing method such as a float method that can secure a long annealing zone at the time of forming the glass substrate is preferable.

As described above, the optically measured residual stress is exactly a deviation stress. That is, the stress difference in two directions orthogonal to each other in a plane perpendicular to the optical axis is measured. In the peripheral portion of the glass substrate, since the substrate is cut at the side, no stress is applied in a direction perpendicular to the side, and a stress due to strain remains only in a direction parallel to the side. Therefore, the deviation stress near the side becomes substantially equal to the residual stress. On the other hand, the stress due to strain is applied to the deviation stress in the central portion of the substrate from all directions in the plane and is relatively canceled in the orthogonal direction. Therefore, a value smaller than the true residual stress is measured. Therefore, in the present invention, the deviation stress was measured at, for example, 50 mm intervals horizontally and vertically within the glass substrate surface, and the maximum value of the deviation stress at all the measurement points was used as an index.

As a result, it has a substantially rectangular surface shape with a short side of 300 mm or more and a long side of 3000 mm or less, and a plate thickness of 0.3 mm or more and 6 mm or less. When the deviation stress in the substrate plane when measured in the direction is measured by an optical method by irradiating a light beam, when it is 1 MPa or less at all positions in the substrate, more preferably 0.6 MPa or less, It has been found that when the glass substrate is used for fine applications or the like at a pressure of 0.3 MPa or less, the amount of deformation due to cutting becomes small enough to cause no practical problem.

When the substrate area is small, the amount of deformation due to residual stress is small, so that even if deformation occurs, there is no substantial problem. When the substrate dimensions are rectangular, the short side is 300 mm or more, more remarkably when the short side is 500 mm or more,
Since the amount of deformation increases, it is necessary to control the residual stress.
If the short side of the board dimension exceeds 3000 mm in a rectangle,
Due to the problem of weight and substrate deflection, handling of the glass substrate becomes difficult and impractical, so there is no point in controlling the residual stress.

When the thickness of the glass substrate is less than 0.3 mm, the glass substrate is not practical because of a problem in that the strength of the glass substrate is reduced and the deflection is increased. 30 such as plasma display panel
In the case of a substrate for a large display having a mold (about 762 mm diagonally) or more, the thickness is preferably 1.5 mm or more from the viewpoint of strength. If the plate thickness exceeds 6 mm, the weight of the glass substrate becomes too heavy, which is not suitable. In applications where weight reduction is important such as a liquid crystal display, the plate thickness is preferably 1.1 mm or less. Therefore, 1.5 mm or more and 6 mm or less are used for applications such as a plasma display, and 0.3 mm or more and 1.
1 mm or less is preferable.

[0036]

EXAMPLE The amount of deformation caused by cutting a glass substrate is determined by the dimensions of the glass substrate, the cutting position, the residual stress in the glass substrate,
Depends on the longitudinal modulus of glass. In the following, the longitudinal elastic coefficient is 7500 kg / mm ² and the photoelastic constant is 27.6 (n
m / cm) / (MPa) glass substrate was used. The glass substrate is formed to a thickness of 0.7 mm by the float method,
550mm x 670m rectangular glass substrate for test
m was cut out. At this time, the side of 550 mm was in the width direction of the glass ribbon, and the side of 670 mm was in the flow direction of the glass ribbon.

During the production of the test glass substrate, the temperature distribution in the width direction of the glass ribbon was controlled so as to be as uniform as possible, so that residual stress due to strain was reduced. The deviation stress was determined by using the above-mentioned ABR-10A birefringence measuring instrument manufactured by Uniopt Co., Ltd. and converting it from the optical path difference of the birefringence.
The measurement was performed at a distance of 50 mm in each of the vertical and horizontal directions for a total of 143 points on one glass substrate.

A black matrix for a color filter was formed on the glass substrate on which the stress was measured, and the positions of the corners of the black matrix were measured with a precision length measuring machine (UMIC800 manufactured by Sokia Corporation). Specifically, a rectangle (size: 244.494 mm × 18) is formed on the glass substrate.
(3.893 mm) Six rectangular patterns were formed, and the X and Y coordinates of the vertices of each rectangle were measured. The arrangement of the rectangles is the positional relationship shown in FIGS. 5 and 6, and the interval between adjacent rectangles is 27 mm in both the X and Y directions.

The glass substrate was cut in half in a direction parallel to the side of 670 mm, that is, cut into a size of 275 mm × 670 mm, and the corners of the black matrix were measured again to evaluate the amount of deformation before and after cutting.

Table 1 shows the direction of the deviation stress and the maximum stress of the substrate, and the direction of deformation after cutting and the maximum amount of deformation. The optical path difference is also shown. In the table, samples 1 to 6 are examples and sample 7 is a comparative example. That is, samples 1 to 6
This is a sample in which the temperature distribution in the width direction of the glass ribbon is controlled to be as uniform as possible. Among them, samples 1 to 3
It is presumed that the temperature of the central portion of the glass ribbon was slightly higher than that of the peripheral portion, and that the temperature of the central portion of the glass ribbon of Samples 4 to 6 was slightly lower than that of the peripheral portion.

[0041]

[Table 1]

The glass substrates of Samples 1 to 3 have a stress distribution in the compression direction along the periphery, and are deformed inward because the compressed portion is opened and stretched by cutting. on the other hand,
The glass substrates of Samples 4 to 6 have a stress distribution in the tensile direction along the periphery, and the tensile portions are opened and shrunk by cutting, and thus are deformed outward. FIGS. 3 and 4 show the measurement results of the deviation stress for the substrates of Samples 1 and 4, respectively, and FIGS. 5 and 6 show the deformation behavior after cutting.

FIGS. 3 and 4 show ABR-1 manufactured by Uniopt.
As a result of measurement using a 0A birefringence measuring instrument, the center of each circle indicates the measurement point, the length of the diameter of the circle is the magnitude of the deviation stress, and the line drawn as the diameter of the circle is the relative tensile stress. The direction perpendicular to the direction and diameter line indicates the direction in which the compressive stress is relatively generated. In FIG. 3, it can be seen that the line having the circular diameter faces the center of the glass substrate, and the periphery of the glass substrate is in the compression direction. On the other hand, in FIG. 4, the line having the circular diameter is turned around the periphery of the substrate, and it can be seen that the periphery of the glass substrate is in the tensile direction.

FIGS. 5 and 6 show the results of measurement by the above-described precision length measuring machine (UMIC800 manufactured by Sokia Corporation). X,
The unit of the Y axis is mm, and indicates the positional relationship of each rectangle as described above. However, since the displacement amount is small compared to the size of the glass substrate and the rectangle, only the displacement amount is used for easy discrimination. The difference before and after the cutting is enlarged to 10,000 times and displayed.

Each of FIGS. 5 and 6 fixes the measurement point at the lower left corner of the lower left rectangle, and has a length of 27 mm from the fixed point.
With the direction of the 5 mm side (X coordinate) as the immovable direction, the displacement amounts of other points are displayed. The glass substrate having a stress distribution in the compression direction along the periphery is deformed inward (FIG. 5), and the glass substrate having a stress distribution in the tensile direction along the periphery is deformed outward (FIG. 6). I have.

The glass substrate of Sample 7 in Table 1 above is a comparative example. The glass substrate was gradually cooled while heating both ends of the glass ribbon in the width direction of the glass ribbon to generate a tensile stress around the glass ribbon. Glass substrate. A stress of 1 MPa or more remains at the maximum, and the deformation amount is extremely large at 12.6 μm.

[0047]

According to the present invention, the amount of deformation when a glass substrate is cut can be controlled within a range that does not substantially cause a problem.
With the glass substrate of the present invention, when manufacturing a flat panel display, it is possible to easily perform multi-panel formation in which a plurality of patterns are formed on one substrate.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic diagrams illustrating deformation of a glass substrate due to cutting, wherein FIG. 1A is a schematic diagram illustrating a state of residual stress of the glass substrate before cutting, and FIG. FIG. 3C is a schematic diagram illustrating a shape after cutting the substrate, FIG. 3C is a schematic diagram illustrating a state of residual stress of the glass substrate before cutting, and FIG.
(C) is a schematic diagram showing the shape after cutting the glass substrate.

FIGS. 2A and 2B are schematic diagrams of a temperature distribution in a width direction of a glass ribbon and a stress distribution of a cut glass substrate, in which FIG. 2A shows a temperature distribution when a peripheral portion is higher in temperature than a central portion, and FIG.
(A) is a schematic diagram for explaining the state of residual stress after cutting the glass ribbon, (c) is a temperature distribution when the temperature of the peripheral part is lower than that of the central part, and (d) is (c) FIG. 4 is a schematic diagram illustrating a state of residual stress after cutting the glass ribbon of FIG.

FIG. 3 is a diagram showing an example of measuring a deviation stress of a glass substrate whose surrounding is a compressive stress.

FIG. 4 is a diagram illustrating an example of measuring a deviation stress of a glass substrate whose periphery is a tensile stress.

FIG. 5 is a view showing a modified example of cutting a glass substrate having a compressive stress in the periphery.

FIG. 6 is a view showing a modified example of cutting a glass substrate whose surroundings are tensile stress.

[Explanation of symbols]

 1: glass substrate before cutting 2: direction of residual stress 3: glass substrate after cutting

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 HA01 HA08 HA12 HA14 JA05 JA13 MA20 2H090 JA09 JB02 KA05 KA08 LA04 LA05 LA15 4G015 CA01 CA10 CB02 EA03 5C040 GA09 GA10 JA21 KB29 MA23 MA24

Claims (5)

[Claims] 1. The short side is 300 mm or more and the long side is 3000 m.
m is a substantially rectangular surface shape with a thickness of 0.3 mm or less.
As described above, in a glass substrate having a size of 6 mm or less, the deviation stress in the substrate surface as measured in the thickness direction due to the residual strain in the glass substrate is 1 M at all positions in the substrate.
A glass substrate for display having a pressure of Pa or less. 2. A glass substrate having a thickness of 0.3 mm or more and 6 mm or less, which is cut into a substantially rectangular surface shape having a short side of 300 mm or more and a long side of 3000 mm or less, and then heating and cooling. A glass substrate for a display which is subjected to a heat treatment and has a deviation stress in a substrate plane measured in a thickness direction due to residual strain in the glass substrate of 1 MPa or less at all positions in the substrate. 3. A glass substrate having a thickness of 0.3 mm or more and 6 mm or less, which is cut into a substantially rectangular surface shape having a short side of 300 mm or more and a long side of 3000 mm or less, and then heating and cooling. A glass substrate for a display which is not heat-treated and has a deviation stress in the substrate plane as measured in the thickness direction due to residual strain in the glass substrate of 1 MPa or less at all positions in the substrate. 4. The short side is 500 mm or more, and the plate thickness is 1.1 mm.
The following is used for a liquid crystal display panel.
Or the glass substrate for display according to 3. 5. The short side is 500 mm or more, and the plate thickness is 1.5 mm.
The display glass substrate according to claim 1 or 2, which is used for a plasma display panel.