JP4863168B2 - Glass substrate for flat panel display and manufacturing method thereof - Google Patents

Description

  The present invention relates to a glass substrate for a flat panel display, and more particularly to a glass substrate for a liquid crystal display (hereinafter referred to as LCD).

  Flat panel displays such as LCDs use glass as a substrate material. Generally, a glass substrate is manufactured by producing a glass original plate by an overflow downdraw method, a float method, or the like and then dividing the glass substrate into predetermined dimensions.

  Conventionally, the original glass plate is divided by using a diamond cutter or the like to place a scribe (crease) on the surface of the original glass plate and then fold the glass so that the tensile stress is concentrated at the scribe marks. It had been.

  In the glass substrate produced by this method, minute cracks and glass powder are inevitably generated in the vicinity of the edge where the front and back surfaces and the end surface (divided surface) intersect. That is, when a scribing is made on the surface of the glass original plate with a diamond cutter or the like, a minute region on the surface of the glass original plate is broken, and a minute crack (referred to as a median crack) is generated in the thickness direction from the surface of the glass original plate.

  In addition, when a scribe is put on the surface of the glass original plate with a diamond cutter or the like, a force that breaks the glass acts not only in the thickness direction but also in the horizontal direction on the surface of the glass original plate, and a minute crack of about 100 to 150 μm Occurs. This minute crack is called a lateral crack. Lateral cracks cause fine glass powder to adhere to the front and back surfaces of the glass substrate because fine glass pieces are peeled off from the surface of the glass original plate. When the minute glass powder adheres to the front and back surfaces of the glass substrate, it becomes a cause of disconnecting electrodes and wiring in the manufacturing process of the flat panel display, and as a result, the manufacturing efficiency and product characteristics of the flat panel display are impaired. Further, once the fine glass powder is attached to the front and back surfaces of the glass substrate, it is difficult to remove by fine cleaning or the like.

  Under such circumstances, the conventional glass substrate for flat panel display has been chamfered by polishing the front and back surfaces and end surfaces, particularly the edge region, of the glass substrate in order to remove minute cracks.

  Specifically, Patent Document 1 discloses a liquid crystal display device in which a connect pin is disposed in contact with an electrode terminal disposed at an end portion of a glass substrate and a molding agent is formed. There is disclosed a liquid crystal display device characterized in that at least one ridge line is chamfered with respect to a ridge line portion of a glass substrate of an electrode terminal to be contacted, and a chamfering amount of a glass substrate having a plate thickness of 1.1 mm is set to 300 μm. It is described.

  In addition, in paragraph [0017] of the specification of Patent Document 2, in order to remove minute glass powder, the edge region of the glass substrate is polished and chamfered into a convex curved surface (so-called R chamfering). Further, it is described that the front and back surfaces of the glass substrate are also polished.

  Further, in the paragraphs [0008], [0009] and FIG. 4 of Patent Document 3, the entire end surface of the glass substrate is formed in an R shape in order to prevent a situation where minute glass powder adheres to the display surface of the glass substrate. After rough polishing and chamfering in a semicircular shape, finish polishing is performed by press-contacting a corner portion of the rotating grindstone at a predetermined angle.

However, even if the edge region of the glass substrate is chamfered by the above method and the lateral cracks are completely removed, a large amount of fine glass powder is generated by the polishing process, and the fine glass powder is formed on the front and back surfaces of the glass substrate. Since it can adhere, after all, the above-mentioned problem caused by fine glass powder cannot be solved.
JP-A-5-2182 JP-A-7-140450 JP 2002-59346 A

  In recent years, in order to solve the above problems, as a method for dividing a glass original plate, a method in which minute cracks are hardly generated on the front and back surfaces of a glass substrate when a scribe is put on the surface of the glass original plate has been developed. That is, this method is a method in which a laser beam is irradiated on the surface of the glass original plate, a minute region of the glass original plate is heated and expanded, and then the minute region is cooled and contracted with a coolant, and a scribe is put on the surface of the glass original plate. There is a method (hereinafter referred to as “laser scribing”) in which a glass substrate is divided by using a stress generated by thermal expansion of the glass, and then the glass substrate is divided. Unlike the method of scribing with a diamond cutter or the like, laser scribing is unlikely to generate minute cracks, particularly lateral cracks, near the end face and the edge of the glass substrate, and the obtained end face is smooth.

  However, in the glass substrate divided by laser scribing, the angle at which the front and back surfaces of the glass substrate intersect with the end surface is substantially perpendicular, and the edge region of the glass substrate is in a very fragile state. When a glass substrate having a sharp edge region is brought into contact with a positioning device or the like in the manufacturing process of a flat panel display, the contact portion is lost or a minute crack is likely to occur.

  On the other hand, if the chamfering of about several hundred μm is conventionally applied to the edge region of the glass substrate, there is no problem that the edge region of the glass substrate is lost, but since the amount of chamfering of the glass substrate is large, Glass powder is generated and can adhere to the front and back surfaces of the glass substrate, and as a result, conventional problems arise.

  Therefore, the present invention presents an edge structure of a glass substrate for a flat panel display, that is, a chamfered shape, in which minute cracks and minute glass powder are hardly generated, and contributes to improvement of manufacturing efficiency and product characteristics of the flat panel display. Is a technical issue.

As a result of diligent efforts, the inventors have made a glass substrate formed by dividing the glass original plate after laser scribing, to a part or all of the edge where the front and back surfaces and the end surface of the glass substrate intersect. The above technical problem can be solved by forming a chamfered surface and limiting the dimension of the chamfered surface to 18 to 75 μm in the thickness direction of the glass substrate and the arithmetic average roughness Ra of the chamfered surface to 0.2 μm or less. Are proposed as the present invention. That is, in the glass substrate for flat panel display of the present invention, a chamfered surface is formed on part or all of the edge where the front and back surfaces of the glass substrate intersect with the end surface, and the dimension of the chamfered surface is the plate of the glass substrate. The thickness is 18 to 75 μm in the thickness direction, the arithmetic average roughness Ra of the chamfered surface is 0.2 μm or less, and the glass original plate is divided by laser scribing and then manufactured.

  The glass substrate for flat panel displays of the present invention forms a chamfered surface on part or all of the edge where the front and back surfaces of the glass substrate intersect with the end surface. As described above, the edge region where the front and back surfaces of the glass substrate intersect with the end surface is in a very fragile state, and if this region is chamfered, the probability that the glass substrate will be lost in the flat panel display manufacturing process. Can be reduced. Further, in the glass substrate for a flat panel display of the present invention, if a part of the edge where the front and back surfaces of the glass substrate intersect with each other is chamfered, the probability of the glass substrate being lost can be reduced to some extent, By chamfering all the edges where the front and back surfaces and the end surfaces intersect, the probability that the glass substrate is lost can be reliably reduced.

  If the dimension of the chamfered surface is regulated to 18 μm or more in the thickness direction of the glass substrate, it is difficult for the glass substrate to be lost in the flat panel display manufacturing process. On the other hand, if the dimension of the chamfered surface is regulated to 75 μm or less in the thickness direction of the glass substrate, the amount of chamfering of the glass substrate is small, so that it is difficult for fine glass powder to be generated during chamfering. It becomes difficult to adhere to the front and back surfaces of the glass substrate, and the chamfering of the glass substrate can be performed in a short time.

  Moreover, in the manufacturing process of a flat panel display, there exists a heat treatment process in which the glass substrate is heated during the manufacturing process. The glass substrate is not uniformly heat-treated in this heat treatment step, and usually a temperature gradient is generated from the surface of the glass substrate toward the inside of the glass substrate. When a temperature gradient occurs in the glass substrate, tensile stress acts on the front and back surfaces, the end surface, and the chamfered surface of the glass substrate. In such a case, if there are minute cracks in the glass substrate, the probability of the glass substrate being damaged increases. In that respect, according to the present invention, since minute cracks of the glass substrate can be reduced as much as possible, such a situation can be accurately prevented.

  FIG. 1 is a schematic cross-sectional view showing a flat panel display glass substrate before the chamfering process is performed, and a portion where the front and back surfaces 2 and the end surface 3 of the flat panel display glass substrate 1 intersect becomes an edge 4.

  FIG. 2 is a schematic cross-sectional view showing the glass substrate for flat panel display of the present invention. A chamfered surface 5 is formed at the edge where the front and back surfaces 2 and the end surface 3 of the glass substrate 1 for flat panel display intersect.

  FIG. 3A is a schematic cross-sectional view showing the glass substrate for flat panel display of the present invention, and is a schematic cross-sectional view for explaining the meaning of the terms of the present invention. Here, “the dimension of the chamfered surface in the thickness direction of the glass substrate” refers to the length of c in FIG.

  FIG. 4A is a schematic cross-sectional view showing an application example of the glass substrate for flat panel display of the present invention, and a chamfered surface 5 at the edge where the front and back surfaces 2 and the end surface 3 of the glass substrate 1 for flat panel display intersect. And the chamfered surface 5 is a convex curved surface. FIG. 4B is a schematic cross-sectional view for explaining the meaning of the terminology of the present invention. In this case, “the dimension of the chamfered surface in the thickness direction of the glass substrate” is c in FIG. Refers to the length.

  2ndly, the glass substrate for flat panel displays of this invention is characterized by being produced by dividing | segmenting, after laser-scribing a glass original plate. In this way, micro cracks, particularly lateral cracks, do not occur in the glass substrate, and it becomes difficult for the fine glass powder to adhere to the front and back surfaces of the glass substrate, and the end surface of the glass substrate becomes smooth. It is not necessary to polish the end face of the glass substrate, and the glass substrate manufacturing efficiency is improved.

  Third, the glass substrate for flat panel displays of the present invention is characterized in that the arithmetic average roughness Ra of the chamfered surface is 0.2 μm or less. Here, “arithmetic mean roughness Ra” refers to a value measured by a method according to JIS B0601: 2001 (hereinafter simply referred to as JIS B0601), evaluation length 8 mm, cutoff value λc = 0.8 mm, The value measured under the condition of the cutoff ratio λc / λs = 100. In this way, cracks starting from the chamfered surface of the glass substrate are less likely to occur. In order to reduce the arithmetic average roughness Ra of the chamfered surface to 0.2 μm or less, for example, the chamfered surface may be formed or polished with a tiremond film of # 1000 to # 3000.

Fourthly, in the glass substrate for flat panel display of the present invention, the end surface of the glass substrate is preferably an unpolished surface. If the end surface of the glass substrate is not polished, the polishing process is simplified and the manufacturing efficiency of the glass substrate is improved.

  If the glass substrate is scribed using a diamond cutter, etc., the end surface of the resulting glass substrate will be rough, so if the end surface of the glass substrate is not polished, cracks will occur in the glass substrate starting from the end surface of the glass substrate. It becomes easy. On the other hand, in the case of laser scribing, the end surface of the obtained glass substrate is a smooth surface, and cracks starting from the end surface of the glass substrate are unlikely to occur without polishing the end surface of the glass substrate.

Fifth, in the glass substrate for flat panel display of the present invention, the front and back surfaces of the glass substrate are preferably unpolished surfaces. If the front and back surfaces of the glass substrate are not polished, the polishing process is simplified, the production efficiency of the glass substrate is improved, and the probability of generation of minute glass powder is reduced. In addition, if a glass original plate is shape | molded by the overflow downdraw method, arithmetic average roughness Ra of a glass original plate will be 5 nm or less, and even if it does not grind | polish the front and back of a glass substrate, a smooth glass substrate can be obtained.

Sixth, in the glass substrate for flat panel display of the present invention, the intersection angle between the front and back surfaces of the glass substrate and the chamfered surface is 120 to 150 ° and / or the intersection angle between the end surface of the glass substrate and the chamfered surface is 120 to 150 °. Preferably there is . If it does in this way, the establishment that a glass substrate breaks in the manufacturing process of a flat panel display can be reduced significantly. To adjust the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface, and the crossing angle between the end surface of the glass substrate and the chamfered surface, adjust the contact angle of the rotating grindstone with diamond abrasive grains dispersed when chamfering the glass substrate. do it. In addition, if the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface and the crossing angle between the end surface of the glass substrate and the chamfered surface are all set to 120 to 150 °, the probability that the glass substrate is damaged in the manufacturing process of the flat panel display is ensured Can be reduced.

  FIG. 3B is a schematic cross-sectional view showing the glass substrate for flat panel display of the present invention, and is a schematic cross-sectional view for explaining the meaning of the terms of the present invention. Here, the “intersection angle between the front and back surfaces of the glass substrate and the chamfered surface” refers to the angle θ1 in FIG. Further, the “intersection angle between the end surface of the glass substrate and the chamfered surface” refers to the angle θ2 in FIG.

Seventh, it is preferable that the glass substrate for flat panel displays of the present invention has a glass substrate thickness of 0.2 mm or more. If it does in this way, the edge of a glass substrate can be chamfered reliably.

Eighth, in the glass substrate for flat panel display of the present invention, the glass substrate contains substantially no alkali metal oxide as a glass composition, and is SiO ₂ 50 to 70% by mass percentage, Al ₂ O _{3. 10~25%, B 2 O 3 3~20} %, 0~10% MgO, CaO 3~15%, BaO 0~10%, SrO 0~10%, 0~10% ZnO, TiO 2 0~5% , P ₂ O ₅ 0 to 5% is preferable . Here, “substantially no alkali metal oxide” refers to the case where the content of the alkali metal oxide in the glass composition is 0.1% by mass or less. If the glass composition of the glass substrate for flat panel displays is regulated in this way, it can be suitably used for LCDs.

Ninthly, in the glass substrate for flat panel display of the present invention, the flat panel display is preferably an LCD.

10thly, the manufacturing method of the glass substrate for flat panel displays of this invention is (1) dividing | segmenting a glass original plate after carrying out laser scribing to the glass original plate, extract | collecting a glass substrate, (2) front and back of a glass substrate, A chamfered surface is formed by chamfering a part or all of the edge where the end surfaces intersect, and the dimension of the chamfered surface is 18 to 75 μm in the thickness direction of the glass substrate, and the arithmetic average roughness Ra of the chamfered surface is 0. Characterized by chamfering to be 2 μm or less .

  In the glass substrate for a flat panel display of the present invention, the chamfered surface formed at the edge where the front and back surfaces of the glass substrate intersect with each other is not particularly limited in shape, but is in a flat state (uniform slope shape) , Also referred to as thread chamfering). If it does in this way, formation of a chamfered surface will become simple and it can improve the chamfering efficiency of a glass substrate. In the glass substrate for flat panel display of the present invention, the chamfered surface may be a convex curved surface. In this way, the chamfering efficiency is reduced, but even if the chamfered surface of the glass substrate comes into contact with a manufacturing apparatus or the like in the manufacturing process of the flat panel display, cracks starting from the chamfered surface of the glass substrate are unlikely to occur. Become.

In the flat panel glass substrate for a display of the present invention, the arithmetic average roughness Ra of the chamfer is at 0.2μm or less, 0.1 [mu] m or less favorable preferred, more preferably less 0.08 .mu.m, is 0.05μm or less Particularly preferred is 0.03 μm or less. When the arithmetic average roughness Ra of the chamfered surface is larger than 0.2 μm, the chamfered surface of the glass substrate becomes rough, and when the glass substrate comes into contact with the flat panel display manufacturing apparatus, the glass substrate cracks from the chamfered surface as a starting point. Is likely to occur.

  In the glass substrate for flat panel display of the present invention, the 10-point average roughness Rz of the chamfered portion is preferably 1 μm or less, more preferably 0.7 μm or less, further preferably 0.4 μm or less, and particularly preferably 0.25 μm or less. 0.15 μm or less is most preferable. Here, “ten-point average roughness Rz” refers to a value measured by a method based on JIS B0601. In this way, cracks starting from the chamfered surface of the glass substrate are less likely to occur. In order to set the 10-point average roughness Rz of the chamfered surface to 1 μm or less, for example, the chamfered surface may be uniformly polished with a tire diamond film of # 1000 to # 3000.

  In the glass substrate for flat panel display of the present invention, the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface is preferably 120 to 150 °, more preferably 130 to 140 °, and still more preferably 132 to 138 °. If the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface is less than 120 °, the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface will be small, and there will be chipping and cracks in the area where the front and back surfaces of the glass substrate and the chamfered surface intersect. It tends to occur. On the other hand, if the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface is larger than 150 °, the crossing angle between the end surface of the glass substrate and the chamfered surface tends to be small, and there is a chip or crack in the region where the end surface of the glass substrate and the chamfered surface intersect. It tends to occur.

  In the glass substrate for flat panel display of the present invention, the crossing angle between the end surface and the chamfered surface of the glass substrate is preferably 120 to 150 °, more preferably 130 to 140 °, and still more preferably 132 to 138 °. If the crossing angle between the end surface of the glass substrate and the chamfered surface is smaller than 120 °, the crossing angle between the end surface of the glass substrate and the chamfered surface becomes small, and chipping and cracking are likely to occur in the region where the end surface of the glass substrate and the chamfered surface intersect. Become. On the other hand, if the crossing angle between the end surface of the glass substrate and the chamfered surface is larger than 150 °, the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface tends to be small, Cracks are likely to occur.

  In the glass substrate for flat panel display of the present invention, the thickness of the glass substrate is preferably 0.2 mm or more, more preferably 0.2 to 2.0 mm, still more preferably 0.3 to 1.5 mm, 0.4 -1.0 mm is particularly preferred. If the thickness of the glass substrate is smaller than 0.2 mm, the dimension of the chamfered surface becomes too large with respect to the thickness of the glass substrate, and there is a possibility that the glass substrate cannot be accurately positioned in the manufacturing process of the flat panel display. . On the other hand, when the plate thickness of the glass substrate is larger than 2.0 mm, it becomes difficult to divide the glass original plate, and the production efficiency of the glass substrate decreases.

The glass substrate for flat panel displays of the present invention can be applied to glass substrates having various dimensions. For example, the dimensions are 0.1 m ² or more (specifically, 320 mm × 420 mm or more), 0.5 m ² or more ( Specifically, 630 mm × 830 mm or more), 1.0 m ² or more (specifically, 950 mm × 1150 mm or more), further 2.3 m ² or more (specifically, 1400 mm × 1700 mm or more), 3.5 m ^It can be applied to a glass substrate of ² or more (specifically, 1750 mm × 2050 mm or more), 4.8 m ² or more (specifically, 2100 mm × 2300 mm or more). The larger the size of the glass substrate is, the larger the edge region of the glass substrate is, so that the probability of breakage of the glass substrate is increased or the glass powder is liable to adhere, but according to the present invention, this is the case. However, generation | occurrence | production of a micro crack and micro glass powder can be suppressed exactly.

In the glass substrate for flat panel display of the present invention, the glass substrate contains substantially no alkali metal oxide as a glass composition, and is 50 to 70% SiO ₂ and 10 to 25% Al ₂ O _{3 by} mass percentage. , B ₂ O ₃ 3-20%, MgO 0-10%, CaO 3-15%, BaO 0-10%, SrO 0-10%, ZnO 0-10%, TiO ₂ 0-5%, P ₂ O It is preferable to contain _{5 to} 5%. If the glass composition is regulated in this way, it can be suitably used for a glass substrate for LCD. The reason for limiting the glass composition range will be described below.

  When the glass composition does not substantially contain an alkali metal oxide, it is possible to prevent a situation where alkali ions are diffused into the semiconductor material on which the film is formed during the heat treatment and the film characteristics are deteriorated.

SiO ₂ is a component that forms a glass network, and its content is 50 to 70%, preferably 55 to 70%, more preferably 58 to 68%, and still more preferably 59 to 66%. When the content of SiO ₂ is less than 50%, chemical resistance, particularly acid resistance is deteriorated, and it is difficult to reduce the density. On the other hand, when the content of SiO ₂ is more than 70%, the high-temperature viscosity becomes high, the meltability becomes poor, and defects of devitrified foreign matter (cristobalite) are likely to occur in the glass.

Al ₂ O ₃ is a component having an effect of increasing the strain point of glass, and its content is 10 to 25%, preferably 12 to 19%, more preferably 14.5 to 17%. If the content of Al ₂ O ₃ is less than 10%, it becomes difficult to make the strain point 600 ° C. or higher. In addition, Al ₂ O ₃ has a function of improving the Young's modulus of glass and increasing the specific Young's modulus. However, if the content of Al ₂ O ₃ is less than 10%, the Young's modulus tends to decrease, and the ratio The Young's modulus also tends to decrease. On the other hand, when the content of Al ₂ O ₃ is more than 25%, the liquidus temperature becomes high and the devitrification resistance tends to decrease.

B ₂ O ₃ is a component that acts as a flux, lowers viscosity, and improves meltability. On the other hand, glass substrates used in LCDs are required to have high acid resistance, but the acid resistance tends to decrease as the content of B ₂ O ₃ increases. Considering the above points, the content of B ₂ O ₃ is 3 to 20%, preferably 5 to 15%, more preferably 8.6 to 14%, and further preferably 9.5 to 12%. When the content of B ₂ O ₃ is less than 3%, the function as a flux becomes insufficient, and the buffered hydrofluoric acid resistance tends to deteriorate. On the other hand, when the content of B ₂ O ₃ is more than 20%, the strain point of the glass is lowered and the heat resistance is easily lowered, and the acid resistance is easily deteriorated. Furthermore, if the content of B ₂ O ₃ is more than 20%, the Young's modulus decreases and the specific Young's modulus tends to decrease.

  MgO is a component that lowers the viscosity at high temperature and improves the meltability of glass without lowering the strain point. MgO is a component having the effect of reducing the density most among the alkaline earth metal oxides. However, when MgO is contained in a large amount, the liquidus temperature rises and the devitrification resistance tends to decrease. Furthermore, MgO reacts with buffered hydrofluoric acid to form a product, which may adhere to the element on the surface of the glass substrate or adhere to the glass substrate and cause it to become cloudy. There is a limit. Considering the above points, the content of MgO is 0 to 10%, preferably 0 to 2%, more preferably 0 to 1%, and still more preferably 0 to 0.5%.

CaO is also a component that lowers the high-temperature viscosity and significantly improves the meltability of the glass without lowering the strain point, as in MgO, and its content is 3 to 15%, preferably 4 to 12%. Preferably it is 5 to 10%, more preferably 6 to 9%. This kind of alkali-free glass substrate is generally difficult to melt, and in order to supply a large amount of a high-quality glass substrate at a low cost, it is important to increase its meltability. In the above glass composition system can reduce the content of SiO _2, but is most effective for enhancing meltability, reducing the content of SiO _2, in addition to acid resistance is extremely lowered Further, the density and thermal expansion coefficient of the glass are likely to increase. From such a situation, when the content of CaO is less than 3%, it becomes difficult to improve the meltability of the glass. On the other hand, if the content of CaO is more than 15%, the buffered hydrofluoric acid resistance of the glass deteriorates and the surface of the glass substrate is easily eroded, and the reaction product adheres to the surface of the glass substrate. And the thermal expansion coefficient becomes too high.

  BaO is a component that improves the chemical resistance and devitrification resistance of glass. On the other hand, BaO is a component that greatly increases the density and thermal expansion coefficient of glass, and is preferably not contained as much as possible when reducing the density and expansion of the glass substrate. Further, BaO is not preferably contained in a large amount from the viewpoint of the environment. Considering the above points, the content of BaO is 0 to 10%, preferably 0 to 5%, more preferably 0 to 2%, still more preferably 0 to 1%, and particularly preferably 0 to 0.5%. is there.

  SrO is a component that improves the chemical resistance and devitrification resistance of glass, and its content is 0 to 10%, preferably 0 to 6%, more preferably 0 to 4.5%, and still more preferably 0. ~ 1.5%. When the SrO content is more than 10%, the density and the thermal expansion coefficient of the glass tend to increase.

  BaO and SrO are components having a property of particularly increasing the resistance to buffered hydrofluoric acid, and in order to improve the resistance to buffered hydrofluoric acid, the total amount of these components is 0.1% or more (preferably 0.3%). % Or more, more preferably 0.5% or more). However, as described above, when a large amount of BaO and SrO is contained, the density and the thermal expansion coefficient of the glass increase. Therefore, it is desirable to keep these components at 6% or less in total. Within that range, it is desirable to contain these total amounts as much as possible from the viewpoint of improving buffered hydrofluoric acid resistance and devitrification resistance, while reducing the density and thermal expansion coefficient, or environmental aspects. From the viewpoint of consideration, it is desirable to reduce as much as possible.

  ZnO is a component that improves the buffered hydrofluoric acid resistance of the glass substrate and improves the meltability. However, when it is contained in a large amount, the glass tends to devitrify, the strain point is lowered, and the density is increased. It becomes easy to do. Therefore, the content of ZnO is 0 to 10%, preferably 0 to 7%, more preferably 0 to 5%, still more preferably 0 to 3%, particularly preferably 0 to 0.9%, and most preferably 0 to 0%. 0.5%.

  By mixing MgO, CaO, BaO, SrO, and ZnO components, the liquidus temperature of the glass can be remarkably lowered, making it difficult to produce crystalline foreign matters in the glass. As a result, the melting property of the glass The moldability can be improved. However, if the total amount of these components is too small, the function as a flux is not sufficiently exhibited, and in addition to the deterioration of the meltability of the glass, the thermal expansion coefficient becomes too low, and the thermal expansion of the TFT material Coefficients are difficult to match. On the other hand, when the total amount of these components is too large, the density increases, the weight of the glass substrate cannot be reduced, and the specific Young's modulus tends to decrease. Therefore, the total amount of these components is 6 to 20%, preferably 6 to 15%, more preferably 6 to 14%.

TiO ₂ is a component that improves the chemical resistance of glass, particularly acid resistance, and lowers the viscosity at high temperature to improve the meltability. However, when it is contained in a large amount, the glass is colored and its transmittance is impaired. Therefore, it is not preferable as a glass substrate for LCD. Therefore, the content of TiO ₂ is 0 to 5%, preferably 0 to 3%, more preferably 0 to 1%.

P ₂ O ₅ is a component that improves the devitrification resistance of the glass, but if it is contained in a large amount, in addition to the occurrence of phase separation and milky white in the glass, the acid resistance tends to be remarkably deteriorated. Therefore, the content of P ₂ O ₅ is 0 to 5%, preferably 0 to 3%, more preferably 0 to 1%.

In addition to the above components, the glass composition may contain Y ₂ O ₃ , Nb ₂ O ₅ , La ₂ O ₃ in a total amount of up to about 5%. These components have a function of increasing the strain point, Young's modulus, etc., but if they are contained in a large amount, the density increases. Furthermore, as long as the glass properties are not impaired, a refining agent such as metal powder such as As ₂ O ₃ , Sb ₂ O ₃ , Sb ₂ O ₅ , F ₂ , Cl ₂ , SO ₃ , C, or Al, Si is combined. The amount can be contained up to 5%. Further, CeO ₂ , Fe ₂ O _{3 and the} like can be contained as a fining agent in a total amount of up to 5%. It is desirable that As ₂ O ₃ , Sb ₂ O ₃ and / or Sb ₂ O ₅ are not substantially used from the environmental viewpoint.

The manufacturing method of the glass substrate for flat panel displays of this invention is (1) dividing | segmenting a glass original plate after carrying out laser scribing to the glass original plate, extract | collecting a glass substrate, (2) The front and back of a glass substrate and an end surface cross | intersect. A chamfered surface is formed by chamfering part or all of the edge, and the dimension of the chamfered surface is 18 to 75 μm in the thickness direction of the glass substrate, and the arithmetic average roughness Ra of the chamfered surface is 0.2 μm or less . It is characterized by chamfering. In addition, in the manufacturing method of the glass substrate for flat panel displays of this invention, since a preferable aspect and an effect are described in the column of description of the glass substrate for flat panel displays of this invention, it is the description here for convenience. Is omitted.

  Glass raw material is prepared by putting glass raw material prepared to have a desired glass composition into a continuous melting furnace, heating and melting the glass raw material, defoaming it, and then supplying it to a molding device to form the molten glass into a plate shape. However, it can be manufactured by slow cooling.

  Various methods can be adopted as a method for forming the glass original plate. For example, various forming methods such as an overflow down draw method, a float method, a slot down draw method, a redraw method, and a roll out method can be adopted. . In the method for producing a glass substrate for a flat panel display of the present invention, it is preferable to form into a plate shape by a downdraw method, particularly an overflow downdraw method, from the viewpoint of producing a glass substrate having a good surface quality. The reason for this is that, in the case of the overflow downdraw method, the surface to be the surface of the glass substrate does not come into contact with the bowl-shaped refractory, and is molded in a free surface state, so that the glass original plate has good surface quality without polishing. This is because it can be molded. Here, the overflow down draw method is to melt the molten glass from both sides of the heat-resistant bowl-like structure and draw the overflowed molten glass downward while joining at the lower end of the bowl-like structure. This is a method for producing plate-like glass. The structure and material of the bowl-shaped structure are not particularly limited as long as the dimensions and surface accuracy of the glass substrate can be set to a desired state and a quality that can be used for a TFT-LCD glass substrate or the like can be realized. Moreover, in order to perform the downward extending | stretching shaping | molding, you may apply force with what kind of method with respect to a glass original plate. For example, a method may be adopted in which a heat-resistant roll having a sufficiently large width is rotated and stretched in contact with the glass original plate, or a plurality of pairs of heat-resistant rolls are only near the end face of the glass original plate. You may employ | adopt the method of making it contact and extending | stretching.

For laser scribing, a laser beam to be irradiated can be a CO ₂ laser, a CO laser, a YAG laser, or the like.

  When chamfering, chamfer the edges of the glass substrate while spraying a high-pressure water stream from the center of the surface of the glass substrate toward the chamfered surface so that minute glass powder does not adhere to the front and back surfaces of the glass substrate. Is preferred. If it does in this way, in the case of chamfering, the probability that minute glass powder will adhere to the front and back of a glass substrate can further be reduced.

  Hereinafter, the present invention will be described in detail based on examples.

  Sample No. described in Table 1 1-10 were prepared as follows.

  First, a glass original plate was prepared, and a laser scribe line was put on the surface of the glass original plate. The glass original plate used what was shape | molded by the overflow downdraw method, and the glass substrate used OA-10 by Nippon Electric Glass Co., Ltd. The front and back surfaces and end surfaces of the glass substrate were not polished.

  Next, the glass original plate was divided along the laser scribe line to obtain a glass substrate having a thickness of 550 mm × 650 mm × 0.7 mm. Thereafter, a substantially flat chamfered surface was formed on all the edges of the glass substrate so as to have the chamfered dimensions shown in Table 1. When chamfering, a # 3000 diamond polishing machine (resin base material with diamond abrasive grains dispersed) was used. The contact angle of the diamond polishing machine was adjusted so that the crossing angle between the front and back surfaces of the glass substrate and the chamfered surface was 135 °, and the crossing angle between the end surface of the glass substrate and the chamfered surface was 135 °.

  Using the above samples, chamfer dimensions, chamfering time, crack characteristics, and adhesion of glass powder were evaluated. The results are shown in Table 1. The chamfering time and crack characteristics were evaluated by preparing 10 glass substrates having similar chamfering dimensions, measuring 10 times each, and calculating the average value.

  “Chamfering time” was evaluated by measuring the time from chamfering start to chamfering end.

  “Crack characteristics” refers to the height at which a glass substrate is placed and 3.0 g of a spherical metal lump is dropped on the chamfered surface of the glass substrate from the thickness direction of the glass substrate to cause chipping or cracking. It evaluated by measuring. If the chamfered surface of the glass substrate is not cracked or chipped when the metal lump is dropped at a height of 4.5 cm, the crack or chipped due to the chamfered surface will occur in the flat panel display manufacturing process. It can be judged difficult.

  Evaluation of “adhesion of glass powder” is “◯” when glass powder of 10 μm or more is not adhered to the front and back surfaces of the glass substrate, and glass powder of 10 μm or more is adhered to the front and back surfaces of the glass substrate. Was evaluated with “×”.

  As is clear from Table 1, sample No. In Nos. 1 to 8, since the dimension of the chamfered surface in the thickness direction is regulated to 20 to 70 μm, the chamfering time is 1.6 seconds or less, and the chamfering can be performed in a short time. Sample No. In Nos. 1 to 8, the evaluation of the crack characteristics is 5 cm or more, and it can be determined that cracks and chips are hardly generated in the glass substrate in the production process of the flat panel display. Furthermore, sample no. In Nos. 1 to 8, since the amount of chamfering was small, glass powder was not attached to the front and back surfaces of the glass substrate.

  On the other hand, as apparent from Table 1, the sample No. Since No. 9 had a chamfered surface dimension of 10 μm in the thickness direction, the crack characteristics were poor. In addition, Sample No. In No. 10, since the dimension of the chamfered surface in the plate thickness direction was 80 μm, in addition to the chamfering time being unduly lengthened, adhesion of glass powder was observed on the front and back surfaces of the glass substrate.

  As is clear from the above description, the glass substrate for flat panel display of the present invention can be applied to various flat panel displays, such as LCD, plasma display panel (PDP), organic electroluminescence display, inorganic electroluminescence display. The present invention can be applied to various types of field emission displays (FED), fluorescent display tubes (VFD), and the like having various electron-emitting devices.

It is a cross-sectional schematic diagram which shows the glass substrate for flat panel displays before a chamfering process is performed. It is a section schematic diagram showing the glass substrate for flat panel displays of the present invention. It is a section schematic diagram showing the glass substrate for flat panel displays of the present invention, and is a section schematic diagram for explaining the meaning of the term of the present invention. (A) It is a cross-sectional schematic diagram which shows the application example of the glass substrate for flat panel displays of this invention. (B) It is sectional schematic which shows the application example of the glass substrate for flat panel displays of this invention, and is sectional schematic for demonstrating the meaning of the term of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate for flat panel displays 2 Front and back surfaces of glass substrate 3 End surface of glass substrate 4 Edge 5 where front and back surfaces of glass substrate intersect each other

Claims (8)

Chamfer part or all of the edges the front and back surfaces and the end surface of the glass substrate intersect is formed, and the dimensions of the chamfered surface, Ri 18~75μm der in the thickness direction of the glass substrate, the chamfered surface A glass substrate for a flat panel display, which has an arithmetic average roughness Ra of 0.2 μm or less and is manufactured by dividing a glass original plate after laser scribing . The glass substrate for a flat panel display according to claim 1, wherein an end surface of the glass substrate is an unpolished surface. The glass substrate for a flat panel display according to claim 1 or 2 , wherein the front and back surfaces of the glass substrate are unpolished surfaces. To any one of claims 1 to 3, wherein the crossing angle of the end surface and the chamfered surface of the crossing angle of the front and back surfaces and the chamfered surface of the glass substrate is 120 to 150 ° and / or the glass substrate is 120 to 150 ° The glass substrate for flat panel displays as described. The plate | board thickness of a glass substrate is 0.2 mm or more, The glass substrate for flat panel displays in any one of Claims 1-4 characterized by the above-mentioned. The glass substrate substantially does not contain an alkali metal oxide as a glass composition, and is SiO ₂ 50 to 70%, Al ₂ O ₃ 10 to 25%, B ₂ O _{3 3 to} 20%, MgO in mass percentage. 0~10%, CaO 3~15%, BaO 0~10%, SrO 0~10%, 0~10% ZnO, TiO 2 0~5%, and characterized in that it contains _P 2 O 5 _0~5% The flat panel display substrate according to any one of claims 1 to 5 . A flat panel display is a liquid crystal display, The glass substrate for flat panel displays in any one of Claims 1-6 characterized by the above-mentioned. (1) After laser scribing to the glass original plate, the glass original plate is divided, and the glass substrate is collected.
(2) front and back surfaces and the end surface of the glass substrate to form a chamfered surface by chamfering a portion or all of the edges that intersect, and the dimensions of the chamfered surface, 18～75Myuemu in the thickness direction of the glass substrate, chamfering A method for producing a glass substrate for a flat panel display, comprising chamfering so that an arithmetic average roughness Ra of the surface is 0.2 μm or less .