JP6379678B2 - Manufacturing method of glass substrate - Google Patents

Description

  The present invention is a glass substrate used for flat panel displays such as liquid crystal displays and organic EL displays, organic EL lighting, solar cells, lithium ion batteries, digital signage, touch panels, electronic paper, mobile phones and smartphones. It relates to the manufacturing method.

  In recent years, with the advent of smartphones and tablet-type terminals, flat panel displays (hereinafter referred to as FPD) have become thinner and lighter, and higher definition has been advanced.

  As a substrate for FPD, a glass substrate is widely used, and in response to the demands for reducing the thickness and weight, the reduction of the thickness of the glass substrate is promoted.

  There are various molding methods such as the float method and the rollout method as the glass substrate molding method. For reasons such as excellent smoothness of the glass substrate to be molded, the downdraw method represented by the overflow downdraw method is used. The law is widely used.

In the downdraw method, the current situation is that the glass substrate is made thinner by increasing the glass drawing speed.

  However, in the case of the downdraw method, since the long glass that is the base of the glass substrate is moved downward while passing through the slow cooling zone, if the drawing speed is increased, the residence time in the slow cooling zone is shortened. Solidifies in a rapidly cooled state. As a result, when such a glass substrate is used for FPD, there is a problem that the thermal shrinkage of the glass substrate increases during the heat treatment included in the manufacturing process.

  Specifically, when a thin film electric circuit is formed on the surface of the glass substrate in the FPD manufacturing process, the glass substrate is subjected to heat treatment at a high temperature. At this time, if the thermal contraction of the glass substrate is large, the circuit pattern formed on the surface of the glass substrate may be deviated from the design, which may cause a serious trouble that the desired electrical performance cannot be maintained.

  Therefore, Patent Document 1 below discloses that the formed glass substrate is slowly cooled again in a slow cooling furnace before the FPD manufacturing process. By increasing the heating temperature in the slow cooling furnace or securing a long slow cooling time, the thermal shrinkage rate generated in the glass substrate can be reduced.

JP-A-5-330836

  However, when the annealing temperature is increased or the annealing time is increased, the thermal shrinkage rate itself is reduced, but on the other hand, the glass substrate is thermally deformed and the warpage generated in the glass substrate is increased. There was a problem. The warpage generated in the glass substrate became particularly noticeable when the glass substrate was thinned. When the warp of the glass substrate is large, there is a high possibility that problems may occur in each process such as conveyance, exposure, and cell formation during FPD manufacturing.

  The present invention has been made to solve the above-described problems of the prior art, and provides a glass substrate that does not warp even if it is thinned, and can be used for high-definition FPD applications without any problem. With the goal.

  As a result of earnest research on the slow cooling of the glass substrate, the present inventor found that when the glass substrate is placed on the setter and heat-treated to perform the slow cooling, the warpage of the glass substrate that occurs after the heat treatment is the peripheral portion of the glass substrate. The present invention was found to be particularly prominent and found that the central portion other than the peripheral portion of the glass substrate hardly warped.

  That is, the present invention devised to solve the above problems is a method of manufacturing a glass substrate having a first dimension, and a glass substrate having a second dimension larger than the first dimension is placed on a setter. A laminated body production step for producing a laminated body by placing the laminated body, a heat treatment step in which the laminated body is placed in a heat treatment furnace to perform a heat treatment, and a measurement step for measuring a warpage amount of the glass substrate after the heat treatment; And a cutting step of cutting and removing a peripheral portion of the glass substrate after the measurement to obtain the first dimension.

  The said structure WHEREIN: It is preferable to determine the cutting width of the peripheral part of the said glass substrate on the basis of the said curvature amount obtained at the said measurement process at the said cutting process.

  The said structure WHEREIN: It is preferable to determine a said 2nd dimension on the basis of the said curvature amount obtained at the said measurement process at the said laminated body production process.

  The said structure WHEREIN: It is preferable to abbreviate | omit the said measurement process after the determination of the said cutting width and a said 2nd dimension.

  The said structure WHEREIN: It is preferable that the maximum temperature of the said heat processing process is lower than the annealing point of the said glass substrate.

  The said structure WHEREIN: It is preferable that the said cutting width is 5-50 mm from the glass substrate edge.

  The said structure WHEREIN: It is preferable that the temperature decreasing rate in the said heat processing process is 1 degree-C / min or more.

  The said structure WHEREIN: It is preferable that the plate | board thickness of the said glass substrate is 500 micrometers or less.

  According to the present invention, it is possible to produce a thin glass substrate having a small thermal shrinkage rate and no warpage.

1 shows a method for manufacturing a glass substrate according to the present invention. It is explanatory drawing of the manufacturing apparatus of a glass substrate and a setter. It is the figure which showed an example of the laminated body preparation apparatus. It is the figure which showed an example of the heat processing furnace. (A)-(c) is a top view for demonstrating the measurement procedure of the thermal contraction rate of a glass substrate.

  Hereinafter, a preferred embodiment of a method for producing a glass substrate according to the present invention will be described with reference to the drawings. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments.

  As shown in FIG. 1, the method for manufacturing a glass substrate according to the present invention includes a laminate production process for producing a laminate 10, a heat treatment process in which the laminate 10 is put into a heat treatment furnace 20 and heat treatment is performed, and a measuring means 30. The measuring process which measures the curvature amount of the glass substrate 11 after heat processing, and the cutting process which cuts and removes the peripheral part 11a of the glass substrate 11 after a measurement with the cutting | disconnection means 40 are made into the 1st dimension.

  The laminated body production process according to the present invention is a process for producing the laminated body 10 by placing a glass substrate 11 having a second dimension larger than the first dimension on the setter 12, as shown in FIG. .

  The glass substrate 11 is made of silicate glass or silica glass, preferably borosilicate glass or soda glass, and most preferably non-alkali glass. Here, the alkali-free glass is a glass that does not substantially contain an alkali component (alkali metal oxide), and specifically, a glass having an alkali component of 3000 ppm or less. The content of the alkali component in the present invention is preferably 1000 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less.

  The strain point of the glass substrate 11 is preferably 600 ° C. or higher, more preferably 650 ° C. or higher, further preferably 680 ° C. or higher, and most preferably 700 ° C. or higher. If the strain point is high, the thermal contraction rate can be reduced even if a high-temperature film-forming process is provided at the time of FPD fabrication. Here, the strain point refers to a value measured based on a method defined in “ASTM C336”.

  The thickness of the glass substrate 11 is preferably 500 μm or less, more preferably 5 μm to 300 μm, still more preferably 5 μm to 200 μm, and most preferably 5 μm to 100 μm. Thereby, the thickness of the glass substrate 11 can be made thinner, and the weight reduction of the electronic device used can be achieved.

  The dimension of the glass substrate 11 in a laminated body production process has a 2nd dimension larger than a 1st dimension. Here, the 1st dimension is a dimension of glass substrate 11 finally produced, and is a dimension of glass substrate 11 after a cutting process mentioned below. A 2nd dimension is a dimension which considered the peripheral part cut and removed at the time of the cutting process mentioned later to the 1st dimension.

  As for the 1st dimension of glass substrate 11, it is preferred that one side is 500 mm or more. As a result, a large number of electronic devices can be manufactured using a single glass substrate 11, and so-called multi-surface processing can be performed. The first dimension is more preferably 700 mm or more, and still more preferably 1000 mm or more.

The setter 12 can be made of a heat-resistant material such as glass, crystallized glass, ceramics, and metal. As with the glass substrate 11, the setter 12 is preferably made of silicate glass, silica glass, borosilicate glass, soda glass, alkali-free glass, or the like. About the setter 12, it is preferable to use the glass with the difference of the thermal expansion coefficient in 30-380 degreeC with the glass substrate 11 within 5 * 10 < ^-7 > / ^degreeC . As a result, even if heat treatment is performed during the heat treatment step described later, the glass substrate 11 and the setter 12 are rubbed with each other due to the difference in expansion coefficient between the glass substrate 11 and the setter 12, so that the glass substrate 11 is damaged. Can be prevented. Most preferably, the setter 12 and the glass substrate 11 use glass having the same composition.

  The thickness of the setter 12 is preferably 500 μm or more, and more preferably 700 μm or more. When the thickness of the supporting glass 12 is 500 μm or more, in the heat treatment step described later, the stage on which the stacked body 10 is placed is not a form that supports the entire lower surface of the stacked body 10 but a shelf plate that supports only the edge portion Even if it is a support pin etc. which perform point support, it can prevent that the laminated body 10 bends. The thickness of the setter 12 is more preferably 1 mm or more and 1.2 mm or more.

  The dimension of the setter 12 is preferably larger than the first dimension of the glass substrate 11 and more preferably larger than the second dimension. Since the size of the setter 12 is larger than the size of the glass substrate 11, it is possible to prevent sagging that occurs in the peripheral portion 11 a of the glass substrate 11 due to the glass substrate 11 protruding from the setter 12, and warping or the like occurs. It can be set as the glass substrate 11 with few. In addition, when the glass substrate 11 is heated or lowered after the heat treatment described later, the setter 12 supports the entire surface of the glass substrate 11, and temperature unevenness can be prevented from occurring in the glass substrate 11.

An inorganic thin film is preferably formed on the upper surface of the setter 12 (the surface on which the glass substrate 11 is placed). By forming the inorganic thin film, it is possible to prevent the glass substrate 11 and the setter 12 from being fixed after heat treatment, particularly when glass is used as the setter 12. As the inorganic thin film to be formed, ITO, Ti, Si, Au, Ag, Al, Cr, Cu, Mg, Ti, SiO, SiO ₂ , Al ₂ O ₃ , MgO, Y ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , Sc ₂ O ₃ , WO ₃ , HfO ₂ , In ₂ O ₃ , ITO, ZrO ₂ , Nd ₂ O ₃ , Ta ₂ O ₅ , CeO ₂ , Nb ₂ O ₅ , TiO, TiO ₂ , Ti ₃ It is preferably formed of one or more selected from O ₅ , NiO, ZnO, SiN, and AlN. In particular, the inorganic thin film is preferably formed of an oxide such as ITO. In the case of an oxide thin film, since it is thermally stable, the same setter 12 can be repeatedly used for a slow cooling process. Note that an inorganic thin film may be formed on the front and back surfaces of the setter 12 so that both the front and back surfaces of the setter 12 can be used.

  The thickness of the inorganic thin film formed on the upper surface of the setter 12 is preferably 5 nm to 500 nm, more preferably 5 nm to 400 nm, and most preferably 5 nm to 300 nm. If the thickness of the inorganic thin film is less than 5 nm, the glass substrate 11 may be difficult to peel from the setter 12 depending on the temperature in the heat treatment described later.

  As a method of forming the inorganic thin film on the setter 12, a known method can be used, for example, a sputtering method, a vapor deposition method, a CVD method, a sol-gel method, or the like can be used.

  The glass substrate 11 and the setter 12 used in the present invention are preferably formed by the down draw method, and more preferably formed by the overflow down draw method. In particular, the overflow downdraw method shown in FIG. 2 is a molding method in which both surfaces of the glass plate do not come into contact with the molded member at the time of molding, and the both surfaces (translucent surface) of the obtained glass plate are hardly scratched and polished. Even if not, high surface quality can be obtained. Of course, the glass substrate 11 and / or the setter 12 may be formed by a float method, a slot down draw method, a roll out method, an up draw method, a redraw method, or the like.

FIG. 2 is a view showing a method of manufacturing the glass substrate 11 and the setter 12 according to the present invention.
Inside the molding furnace 51 of the manufacturing apparatus 50, a molded body 52 having an outer surface shape with a wedge-shaped cross section is disposed, and glass (molten glass) melted in a melting furnace (not shown) is supplied to the molded body 52. Thus, the molten glass overflows from the top of the molded body 52. And the molten glass which overflowed passes along the both sides | surfaces which exhibit the cross-sectional wedge shape of the molded object 52, and joins by a lower end, The shaping | molding of the glass ribbon G is started from molten glass. The glass ribbon G immediately after joining at the lower end of the molded body 52 is drawn downward while being contracted in the width direction by the cooling roller (edge roller) 53, and thinned to a predetermined thickness. Next, the glass ribbon G having reached the predetermined thickness is sent out by a roller 54, and then gradually cooled in a slow cooling furnace (annealer) to remove the thermal distortion of the glass ribbon G, and the glass ribbon G that has been gradually cooled is heated to about room temperature. It is designed to cool sufficiently to the temperature. After the glass ribbon G that has passed through the slow cooling furnace is changed in the traveling direction from the vertical direction to the horizontal direction by the bending auxiliary roller 55, unnecessary portions (cooling roller 53, roller 54, etc.) that exist at both ends in the width direction of the glass ribbon G are used. The contacted part) is cut by the longitudinal cutting device 56. Then, the glass substrate 11 used by this invention can be obtained by cut | disconnecting for every predetermined width with the width direction cutting device 57. FIG. Alternatively, the glass substrate 11 may be manufactured by cutting and removing unnecessary portions of the glass film ribbon G with the longitudinal direction cutting device 56 after cutting in the width direction with the width direction cutting device 57. Further, in the manufacturing apparatus 50 described above, the method for producing the glass substrate 11 by the single wafer type has been described. However, the present invention is not limited to this, and the longitudinal cutting device 56 cuts unnecessary portions and then cuts in the width direction. Alternatively, a glass roll may be produced by winding the glass ribbon G into a roll shape through a slip sheet. Further, in the manufacturing apparatus 50 described above, the method of manufacturing the glass substrate 11 that is a flexible glass film has been described. However, in the case of manufacturing the glass substrate 11 and the setter 12 having a relatively large thickness, the bending aid is used. The glass substrate 11 and the setter 12 can be manufactured in a single-wafer type by cutting each predetermined width with the width direction cutting device 57 without providing the roller 55 in the vertical posture.

  FIG. 3 is a view showing an example of an apparatus for producing the laminate 10 according to the present invention.

  When the laminated body 10 is manufactured, it is preferable to place the glass substrate 11 on the setter 12 while the lower surface of the glass substrate 11 is supported by the support means 60 as shown in FIG. This is because it is not desirable to contact the upper surface of the glass substrate 11 with a suction pad or the like (not shown) because the upper surface of the glass substrate 11 is a guarantee surface for performing a film forming process or the like when the FPD is manufactured.

  In FIG. 3, the lower surfaces of two opposite sides of the glass substrate 11 are directly supported from below by a plurality of support rollers 42 provided on the support arm 61 of the support means 60. As a result, the glass substrate 11 is supported by the support roller 42 of the support arm 61 while being bent downward in a convex shape. Thereafter, the glass substrate 11 and the setter 12 are brought relatively close to each other so that the convex portion of the glass substrate 11 is brought into contact with the setter 12. The laminated body 10 is produced by placing the glass substrate 11 on the setter 12 by separating the supporting means 60 facing each other thereafter.

  As shown in FIG. 1, the heat treatment step of the present invention is a step of performing a slow cooling treatment for reducing the thermal shrinkage rate of the glass substrate 11 by putting the laminate 10 into a heat treatment furnace 20.

  The maximum temperature in the heat treatment step of the present invention is preferably lower than the annealing point of the glass substrate 11. Thereby, the quantity of the curvature which arises in the glass substrate 11 after heat processing can be reduced. On the other hand, the maximum temperature in the heat treatment step is preferably higher than a temperature that is 150 ° C. lower than the strain point of the glass substrate 11. Thereby, the thermal contraction rate of the glass substrate 11 can be reduced. The maximum temperature in the heat treatment process is preferably substantially the same as the maximum temperature in a process (such as a film forming process for FPD manufacturing) in which the manufactured glass substrate 11 is used. Thereby, since the highest temperature of a heat treatment process can be set most efficiently, the production efficiency of the glass substrate 11 will improve.

  The rate of temperature increase up to the maximum temperature in the heat treatment step of the present invention is preferably 3 ° C./min or more, more preferably 5 ° C./min or more, and further preferably 7 ° C./min or more. Thereby, the time of a heat treatment process can be shortened. The rate of temperature increase is preferably 20 ° C./min or less, more preferably 15 ° C./min or less, in order to reduce the probability that the glass substrate 11 is broken.

  The holding time at the maximum temperature in the heat treatment step of the present invention depends on the second dimension of the glass substrate 11 but is preferably 5 to 120 minutes. Thereby, the thermal contraction rate of the glass substrate 11 can be reduced.

  The rate of temperature decrease from the maximum temperature in the heat treatment step of the present invention is preferably 1 ° C./min or more. Thereby, the production efficiency of the glass substrate 11 can be improved. When the temperature lowering rate is increased, the glass substrate 11 tends to be warped. However, the glass substrate manufacturing method of the present invention cuts and removes the warped portion of the glass substrate 11 in the cutting step described later. The speed can be increased. The temperature lowering rate is more preferably 2 ° C./min or more, and further preferably 5 ° C./min or more. On the other hand, from the viewpoint of sufficiently reducing the thermal shrinkage rate of the glass substrate 11, the rate of temperature decrease is more preferably 20 ° C./min or less, and more preferably 15 ° C./min or less.

  The heat treatment process in the present invention may use an on-line heat treatment furnace 20 using a roller conveyor, a belt conveyor, a walking beam system, or the like. However, as shown in FIG. good.

  As shown in FIG. 4, the heat treatment furnace 20 includes a glass chamber 21, a glass shelf 22 disposed inside the glass chamber 21, an elevator 23 on which the glass shelf 22 is placed, and a periphery of the glass chamber 21. A surrounding furnace wall 24 and a heater 25 for heating the glass chamber 21 from the outside are provided. The heat treatment furnace 20 is preferably disposed in a clean room (not shown).

  The glass chamber 4 has a covered cylindrical shape formed by integrally molding quartz glass, and has a slow cooling space S therein. That is, the glass chamber 4 defines the slow cooling space S by a continuous continuous surface. Thereby, even if dust generation etc. arise from the furnace wall 24, it can prevent that the glass substrate 11 is contaminated. The glass chamber 4 may be formed on a continuous continuous surface by welding with a laser or the like.

  As shown in FIG. 4, the glass shelf 22 is disposed in the slow cooling space S provided in the glass chamber 21, and the setter 12 is provided on each of the shelf plates 27 provided in the accommodating portion 26 of the glass shelf 22. The laminated body 10 formed by laminating the glass substrate 11 is accommodated. Then, after that, the slow cooling space S is heated from the outside of the glass chamber 21 by the heater 25 to gradually cool each glass substrate 11 accommodated in each accommodating portion 26.

  According to this, since the glass chamber 21 defines the slow cooling space S by a continuous continuous surface, minute foreign matters such as dust enter the slow cooling space S from the outside of the glass chamber 21. Can be prevented.

  Here, since it accommodates in the state of the laminated body 10 which laminated | stacked the glass substrate 11 on the setter 12 in the accommodating part 26 of the glass shelf 22, it suppresses the bending by the dead weight of the glass substrate 11 at the time of slow cooling. Can do. As a result, generation | occurrence | production of the damage | wound by the contact between glass substrates 11 can be reduced as much as possible. In FIG. 4, since the entire surface of the glass substrate 11 is supported by the setter 12, it is easy to make the in-plane temperature distribution of the glass substrate 11 uniform.

  The glass substrate manufacturing method according to the present invention may include a cleaning step for the glass substrate 11 before the heat treatment step. Thereby, even if it is a case where a foreign material adheres to the glass substrate 11, it can prevent that the adhered foreign material is baked on the surface of the glass substrate 11 by a heat treatment process. The cleaning process of the glass substrate 11 may be performed before the laminate manufacturing process, or may be performed between the laminate manufacturing process and the heat treatment process.

  The measurement process of the present invention is a process of measuring the amount of warpage generated in the glass substrate 11 after the heat treatment, as shown in FIG.

  In the measurement process, as shown in FIG. 1, 100% inspection may be performed online, or the amount of warpage of the glass substrate 11 may be measured offline by sampling. As the measuring means 30 for the warpage amount of the glass substrate 11, a measuring device for measuring the optical warpage amount using a laser displacement sensor may be used, or it may be physically measured using a cinex gauge or the like. .

  The reason why the thermal deformation (warpage) becomes particularly large in the peripheral portion 11a of the glass substrate 11 is considered to be influenced by the temperature distribution in the surface of the glass substrate 11 when the temperature is lowered in the heat treatment step. That is, when the temperature of the glass substrate 11 is lowered, the glass substrate 11 is cooled from the peripheral portion 11a toward the central portion, so that when the central portion is sufficiently cooled and contracted, the peripheral portion 11a of the glass substrate 11 is warped. It is inferred that this will occur. For this reason, it is considered that the warpage generated in the glass substrate 11 can be reduced by using an expensive heat treatment furnace with extremely high temperature uniformity even when the temperature is lowered, or by setting the temperature lowering rate to be low. Increases or the production efficiency deteriorates. As a result of earnest research on the slow cooling of the glass substrate, the present inventor found that when the glass substrate is placed on the setter and heat-treated to perform the slow cooling, the warpage of the glass substrate that occurs after the heat treatment is the peripheral portion of the glass substrate. And it was found that the center portion other than the peripheral portion of the glass substrate was hardly warped. Therefore, by cutting and removing the peripheral portion 11a of the glass substrate 11 in which the warp has occurred by a cutting process described later, the glass substrate 11 having a small warp and a small thermal shrinkage rate is manufactured without deteriorating the manufacturing cost and the manufacturing efficiency. can do.

  It is preferable to determine the cutting width of the peripheral portion 11a of the glass substrate 11 in the cutting step to be described later on the basis of the warpage amount of the glass substrate 11 obtained in the measurement step. Thereby, the glass substrate 11 which has a 1st dimension which is a desired dimension can be extract | collected. The cutting width of the peripheral portion 11a of the glass substrate 11 is preferably from the edge of the glass substrate 11 to a region where the glass substrate 11 is warped (region spaced from the setter 12). If the amount of warpage of the glass substrate 11 is within the standard range, the cutting width may be determined so as to leave a region where some warpage has occurred. The cutting width is preferably 5 to 50 mm from the edge of the glass substrate. Since the region with the largest amount of warpage generated in the glass substrate 11 can be cut, the manufacturing cost of the glass substrate 11 can be reduced.

  The second dimension is preferably determined based on the amount of warpage of the glass substrate 11 obtained in the measurement process. That is, the second dimension is a dimension of the glass substrate 11 obtained by adding a cutting width to the first dimension. Thereby, it becomes possible to cut and remove a region having a large warp effectively.

  After determining the cutting width and the second dimension of the glass substrate 11, it is preferable to manufacture the glass substrate by omitting the measurement step. Thereby, the glass substrate 11 can be manufactured efficiently. Once the cutting width and the second dimension of the glass substrate 11 are determined, if the temperature conditions of the heat treatment process are the same, it is possible to consider that the warpage amount generated in the glass substrate 11 is the same in the same lot. Therefore, the measurement process can be omitted.

  The cutting step of the present invention is a step of cutting and removing the peripheral portion 11a of the glass substrate 11 after measurement as shown in FIG.

  As the cutting means 40, a scribe cleaving method, a laser cleaving method, a laser fusing method, a dicing method, a water jet method, an etching method, or the like can be used. When the thickness of the glass substrate 11 is small as the cutting means 40 (for example, a thickness of 300 μm or less), an initial crack is formed at the end of the glass substrate 11 while applying a bending stress on the planned cutting line of the glass substrate 11. Bending stress cleaving for cleaving the glass substrate 11 may be employed.

  After the cutting step, as shown in FIG. 1, the glass substrate 11 can be obtained by taking out the glass substrate 11 from the setter 12 and having a small thermal shrinkage rate and little warpage. In addition, after taking out the glass substrate 11 from the setter 12, you may perform a cutting process.

  End face processing may be performed on the cut end face after the cutting step. Thereby, it can prevent that glass powder etc. generate | occur | produce from a cut end surface. As the end surface processing, end surface processing may be performed by end surface processing using a grooved grindstone or by end surface etching using hydrofluoric acid or the like.

  You may perform the washing | cleaning process of the glass substrate 11 after a cutting process or an end surface process. Thereby, even if the glass powder etc. which arose at the time of a cutting process or an end surface process adhered to the surface of the glass substrate 11, it can be removed. The washing method is not particularly limited, and an alkaline detergent may be used or pure water washing may be performed.

  As described above, according to the present invention, it is possible to manufacture a glass substrate having both a low heat shrinkage rate and high flatness, and thus it is possible to manufacture a glass substrate particularly suitable for high-definition display applications. .

  Hereinafter, although the manufacturing method of the glass substrate of this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

(Measurement of warpage of glass substrate)
A rectangular transparent glass plate having a length of 700 mm, a width of 800 mm, and a thickness of 500 μm was used as a glass substrate. The glass substrate is an alkali-free glass manufactured by Nippon Electric Glass Co., Ltd. (Product name: OA-11, coefficient of thermal expansion at 30 to 380 ° C .: 38 × 10 ⁻⁷ / ° C., strain point 685 ° C., annealing point 740 ° C.) It was used. The amount of warpage of the 15 glass substrates was measured with a Toshiba glass substrate warpage measuring machine. The maximum amount of warpage was 20-30 μm.

(Measurement of thermal shrinkage of glass substrate)
The measurement of the thermal shrinkage rate of the 15 glass substrates was performed as follows. As shown in FIG. 5A, first, a 160 mm × 30 mm strip sample T is prepared as a glass substrate sample. A marking M is formed at a position 20 to 40 mm away from the edge using # 1000mp water-resistant abrasive paper on each of both ends in the long side direction of the strip-shaped sample T. Thereafter, as shown in FIG. 5B, the strip-shaped sample T on which the marking M is formed is folded in two along the direction orthogonal to the marking M, thereby preparing sample pieces Ta and Tb. Then, after heat-treating only one sample piece Tb under a predetermined condition, as shown in FIG. 5C, the sample piece Ta that has not been heat-treated and the sample piece Tb that has been heat-treated are arranged in parallel. The amount of positional deviation (ΔL1, ΔL2) of the marking M on the two sample pieces Ta and Tb is read with a laser microscope, and the thermal contraction rate is calculated by the following equation. Note that l ₀ in the equation is a distance between the initial markings M.

Thermal contraction rate = [{ΔL1 (μm) + ΔL2 (μm)} × 10 ³ ] / l ₀ (mm) (ppm)

The heat treatment conditions at the time of thermal shrinkage evaluation were performed by a temperature profile in which the temperature was raised from room temperature to 500 ° C. at 5 ° C./min, held at 500 ° C. for 1 hour, and then cooled from 500 ° C. to 5 ° C./min. The absolute value of the heat shrinkage obtained was in the range of 30 to 35 ppm.

(Heat treatment test)
15 rectangular transparent glass plates having a length of 800 mm, a width of 900 mm, and a thickness of 1.0 mm were used as setters. Also for the setter, non-alkali glass (product name: OA-11, thermal expansion coefficient at 30 to 380 ° C .: 38 × 10 ⁻⁷ / ° C., strain point 685 ° C., annealing point 740 ° C.) manufactured by Nippon Electric Glass Co., Ltd. used. Note that an ITO film having a thickness of 150 nm was formed on both surfaces of the setter by sputtering. The 15 glass substrates described above were each placed on a setter to produce 15 sets of laminates. The prepared laminate is put into a multi-stage heat treatment furnace, heated to 600 ° C. at 10 ° C./min, held at 600 ° C. for 90 minutes, and lowered from 600 ° C. to room temperature at 3 ° C./min. Heat treatment was performed in the profile. About the glass substrate after heat processing, the thermal contraction rate measurement and the measurement of the amount of curvature were performed similarly to the above. In all the glass substrates, the absolute value of the heat shrinkage rate was a very small value of 5 ppm or less. The maximum value of the warp amount was 80 to 120 μm, which was larger than before the heat treatment. When a region having a larger value than the warpage amount (20 to 30 μm) before the heat treatment was defined as a heat deformation region, the heat deformation region of the glass substrate after the heat treatment was in a range of 30 to 50 mm.

(Cutting test)
The peripheral part of the glass substrate after the heat treatment was cut and removed from the end by 5, 10, 30, 50 mm by a scribing method using a diamond wheel chip. The amount of warpage and thermal shrinkage of the glass substrate after cutting and removal were measured in the same manner as described above. The results are shown in Table 1.

  The glass substrate whose peripheral portion was cut after the heat treatment has a smaller amount of warpage than the glass substrate whose peripheral portion has not been cut after the heat treatment.

  The present invention is suitable for manufacturing electronic devices such as flat panel displays such as liquid crystal displays and organic EL displays, organic EL lighting, solar cells, lithium ion batteries, digital signage, touch panels, electronic paper, mobile phones and smartphones. Can be used for

10 Laminate
11 Glass substrate 11a Peripheral part 12 Setter 20 Heat treatment furnace 30 Measuring means 40 Cutting means 50 Molding device 60 Support means

Claims (7)

A method for producing a glass substrate having a first dimension,
A laminated body production step of producing a laminated body by placing a glass substrate having a second dimension larger than the first dimension on a setter;
A heat treatment step of performing heat treatment by putting the laminate into a heat treatment furnace;
A measuring step of measuring the amount of warpage of the glass substrate after the heat treatment;
Cutting the peripheral portion of the glass substrate after the measurement to the first dimension ,
The method for manufacturing a glass substrate, wherein the cutting step includes determining a cutting width of a peripheral portion of the glass substrate based on the warpage amount obtained in the measurement step . 2. The method for manufacturing a glass substrate according to claim 1 , wherein, in the laminate manufacturing step, the second dimension is determined based on the amount of warpage obtained in the measurement step. The method for manufacturing a glass substrate according to claim 2 , wherein the measuring step is omitted after the cutting width and the second dimension are determined. The method for producing a glass substrate according to any one of claims 1 to 3 , wherein the maximum temperature of the heat treatment step is lower than the annealing point of the glass substrate. The said cutting width is 5-50 mm from the said glass substrate edge, The manufacturing method of the glass substrate in any one of Claims 1-4 characterized by the above-mentioned. The method for producing a glass substrate according to any one of claims 1 to 5 , wherein the temperature lowering rate in the heat treatment step is 1 ° C / min or more. The thickness of the said glass substrate is 500 micrometers or less, The manufacturing method of the glass substrate in any one of Claims 1-6 characterized by the above-mentioned.