JPH11189423A - Production of glass base plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for glass base plates that can shorten the production steps and can inexpensively provide glass base plate of high dimensional accuracy by increasing the forming accuracy of the glass base plate. SOLUTION: In a production process for glass base plate by pressing molten glass into plates, the press-forming step comprises the direct press step where the molten glass is molded and solidified to a prescribed shape and the repressing step where the glass base plate from the direct press step is repressed under heating conditions to effect fine adjustment of the shape or deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass substrate used as a substrate for a hard disk mainly used as an information recording medium for a computer, and more particularly to a method for manufacturing a glass substrate by improving the molding accuracy of the glass substrate. The present invention relates to a method for manufacturing a glass substrate capable of shortening a process.

[0002]

2. Description of the Related Art In recent years, the spread of computers has rapidly advanced, and the capacity of OS software such as an operation system which affects the operability of the computer and various kinds of program software operating on the OS tend to be increased. In addition, data created by using these programs also tends to have a high capacity.

Accordingly, in the development of a hard disk as an information recording medium capable of recording / reading such a large amount of information at a high speed, hardness and smoothness have been changed in place of a conventional substrate using aluminum metal. There is an increasing movement to use glass substrates that are excellent in quality, particularly glass substrates using crystallized glass.

Generally, a method for manufacturing a glass substrate is divided into a blanking process and a substrate process, as shown in a flowchart of FIG. Here, in the blanking step, first, a molten glass material prepared to have a specific composition is poured into a press mold and press-molded.

In this press molding, as shown in FIG. 11, molten glass 52 extruded from nozzle 51
Is cut by a certain amount with a shear 53, and the periphery is dropped onto a lower mold 55 surrounded by a cylindrical wall of a trunk mold 54. After the upper mold 56 covers the upper surface of the trunk mold 54, the lower mold 55 is pushed up. Upper mold 5
6, a space surrounded by the lower mold 55 and the body mold 54 is densely filled with the molten glass 52 to produce a disk-shaped glass substrate 57.

The glass substrate thus obtained is subjected to a crystallization treatment, and thereafter, the inner hole of the glass substrate is cut to open an inner hole, and the presence or absence of a surface defect such as a chip or a crack is inspected. The glass substrate thus manufactured is called a blank.

Next, in the substrate process,
After lapping (primary lapping) the surface of the blank with an abrasive such as SiC fine powder, the inner and outer diameters are processed into a predetermined size and a predetermined shape (chamfering), and the surface is further wrapped (secondary lapping) and washed. The blank thus obtained is polished using cerium oxide fine powder,
After finishing to a predetermined smoothness, ultrasonic cleaning and IPA cleaning are performed, and finally, the presence or absence of a surface defect or the like is inspected. The blank that has gone through the above steps is called a substrate. By applying a magnetic recording film to the substrate thus obtained, a glass disk is manufactured.

[0008]

As described above, the conventional method for manufacturing a glass substrate (substrate) is composed of many steps, and requires a long processing time such as lapping and polishing. In addition, there is a problem that the processing cost is high because the method includes many steps that require high processing consumable material cost. In addition, there is also a problem that the cost of raw materials required for forming the glass substrate increases because there are many useless portions removed by lapping or the like.

Further, the working environment, that is, the amount of the molten glass extruded, the timing of cutting the extruded molten glass, or the adjustment of the viscosity of the molten glass (so that the molten glass is always supplied to the press die by a certain amount) ( If conditions such as (temperature control) are not constant, glass substrates having different thicknesses are formed each time.

[0010]

Means for Solving the Problems The present invention has been made in view of the above-mentioned problems of the related art, that is,
According to the present invention, in a method for producing a glass substrate including a step of press-molding molten glass into a plate shape, the press-forming step includes a direct press step of solidifying and molding the molten glass into a predetermined shape, and the direct press step. A method for manufacturing a glass substrate, comprising: a reheat pressing step of finely adjusting or deforming the shape by repressing the obtained glass substrate under heating conditions.

In the method for manufacturing a glass substrate of the present invention, in the press forming step,
It is preferable to use a press upper and lower mold having a contact portion that can be directly fitted. In the press forming step, it is preferable to use an upper and lower press die having a space for extruding the surplus volume of the glass to be processed to the outer periphery of the glass to be processed. Further, in the press molding step, at the boundary between the inner hole and / or the outer periphery and the glass substrate,
Preferably, a chamfer is formed.

Further, in the glass substrate obtained after the reheat pressing step in the method for manufacturing a glass substrate of the present invention, the thickness of the inner hole portion and / or the outer peripheral portion of the glass substrate is smaller than that of the glass substrate portion. A trapezoidal shape is preferred. Alternatively, it is also preferable that the glass substrate obtained after the reheat pressing step has a wedge shape in which a notch is formed at a boundary portion between the inner hole portion and / or the outer peripheral portion and the glass substrate portion in the glass substrate,
A shape combining a trapezoidal shape and a wedge shape is also suitably adopted.

[0013] Regardless of whether the process is a direct press process or a reheat press process, the upper and lower press dies used are either trapezoidal, or both wedge-shaped, or one of them is trapezoidal. And the other is wedge-shaped. At this time, there is no restriction as to which shape of the upper die and the lower die to use. In addition, the combination of the direct press process and the upper and lower press dies used in the subsequent reheat press process is trapezoidal or wedge-shaped for a flat plate, or trapezoidal or flat for a trapezoid,
Alternatively, it is preferable to use either a wedge shape or a wedge shape.

Even when the above various press upper and lower dies are used, when a notch is formed in the glass substrate in the reheat press step, a thermal shock is applied to the notch, so that the inner hole is formed in the notch. It is preferable that the part and / or the outer peripheral part be separated from the glass substrate part because unnecessary parts as a product can be easily removed. In addition, as the glass substrate, SiO ₂ —Al ₂ O ₃ −
Li ₂ O-based crystallized glass is preferably used.

[0015]

DETAILED DESCRIPTION OF THE INVENTION As described above, according to the method for manufacturing a glass substrate of the present invention, the post-processing step is greatly shortened, and the convenience is improved, particularly by improving the forming accuracy in the forming step of the glass substrate. Be transformed into Therefore, the production efficiency is improved, and the glass substrate can be supplied at low cost.

The method for manufacturing a glass substrate according to the present invention is not limited to the above-described method for manufacturing a glass substrate for a hard disk, and it goes without saying that the method can be used for manufacturing various other glass substrates. Production of a glass substrate having a flat ring shape used as a glass substrate for a hard disk or the like will be mainly described.

FIG. 1 is an explanatory view showing a method for forming a glass substrate in the method for manufacturing a glass substrate of the present invention. First, the molten glass 2 is extruded or dropped from the nozzle 4 toward the lower die 1 for direct press, and the molten glass is cut by the shear 3 so that a fixed amount is supplied. The glass substrate 11 having a predetermined shape is pressed by being pressed against the lower die 1 for direct press.
Is prepared. This press step is called a direct press step, and such press processing is called a direct press.

Next, the solidified and formed glass substrate 11
Is sucked by the suction plate 6 disposed at the end of the transfer arm 7 and transferred to the lower die 8 for reheat press. Then, the upper die 9 for reheat press is replaced with the lower die 8 for reheat press.
By pressing against and deforming to a predetermined shape. The pressing process at this time is called a reheat pressing process, and such press working is called a reheat pressing. Subsequently, the glass substrate 12 formed into a predetermined shape by the reheat press is transferred by the transfer arm 10 to the next step.

As described above, according to the present invention, in the method for producing a glass substrate including the step of press-forming molten glass into a plate shape, the press-forming step includes a step of solidifying and forming the molten glass into a predetermined shape. And a reheat press step of performing fine adjustment or deformation of the shape by repressing the glass substrate obtained by the direct press step under heating conditions. Hereinafter, the press forming step will be described in detail.

First, in producing the molten glass 2,
A mixture of predetermined raw material powders having a predetermined composition, or a pre-synthesized glass powder or pellets is suitably used as a molten raw material. Furthermore, it is also possible to reuse a portion such as an inner hole portion and an outer peripheral portion separated from the glass substrate once formed by post-processing described later.
The type and composition of the glass used are not particularly limited. However, as the glass substrate for a hard disk, SiO ₂ −
Al ₂ O ₃ -Li ₂ O system crystallized glass is preferably used.

The molten glass 2 is supplied to the direct press lower mold 1 as being extruded or dropped from the nozzle 4. Here, in order to prevent rapid cooling and solidification of the molten glass 2 and occurrence of a large thermal stress accompanying the rapid cooling and solidification of the molten glass 2, the lower die 1 for direct pressing has an appropriate glass transition point and the like of the molten glass 2. It is preferred that the temperature be maintained. Then, the upper mold 5 for direct press, which is maintained at the same temperature as the lower mold 1 for direct press, is pressed against the lower mold 1 for direct press to press the molten glass 2 to be formed into a predetermined shape. The shape design of the upper and lower dies 1 and 5 for direct press will be described later.

FIGS. 2A to 2C are radial cross-sectional views showing various embodiments of the shape of the glass substrate 11 produced by the direct press. Is a typical example. Here, the glass substrate 11 having any shape is formed by extruding the glass substrate portion 11A to be the final glass substrate and the surplus supplied glass of the supplied molten glass 2 to the outer periphery. When producing a glass substrate having an outer peripheral portion 11C and having a shape such as a flat ring shape having an inner hole, it is preferable to provide the inner hole portion 11B in the glass substrate.

The flat plate shape shown in FIG. 2A is not only a glass substrate having no need to form inner holes such as a flat ring shape, but also a flat plate shape.
It is widely used as a precursor shape suitable for producing glass substrates of various shapes such as a flat ring shape by a combination with a reheat press process as a next process. Here, in order to reduce the processing load when the outer peripheral portion 11C is separated from the glass substrate portion 11A in the post-processing step, the outer peripheral portion 1C is removed.
It is preferable that the shape of the upper and lower dies 1.5 for direct press and the supply amount of the molten glass 2 are adjusted so that 1C is formed thinner than the glass substrate portion 11A.

The trapezoidal shape shown in FIG. 2B is an embodiment suitable for producing a flat ring-shaped glass substrate having an inner hole, and the inner hole portion 11 B has an outer peripheral portion in the above-described flat plate shape. As in the case of 11C, it is preferable that the thickness is set to be thinner than the glass substrate portion 11A in order to facilitate separation processing by post-processing.

Further, in the wedge shape shown in FIG. 2C, a notch 13 is formed at a boundary between the inner hole 11B and / or the outer peripheral portion 11C and the glass substrate 11A. By applying a thermal shock to the notch 13, the inner hole 11B and the outer peripheral portion 11C can be easily separated from the glass substrate 11A at the notch 13.

In the shape of the glass substrate 11 illustrated in FIG. 2, a chamfer 14 and a chamfer 14 are formed at the boundary between the inner hole 11B and / or the outer periphery 11C and the glass substrate 11A.
That is, a chamfer is provided. Such a chamfer 14 is used as a product glass substrate (hereinafter, “product”).
It is written. ) Is important in preventing chipping and maintaining mechanical strength, but in the present invention, it is important in omitting a chamfering step which is indispensable in a method of manufacturing a glass substrate according to the prior art. Very high degree.
That is, by forming the chamfer 14 having a certain degree of processing accuracy in a direct press state, the processing accuracy is further increased by a reheat press as a post-process, and the inner hole portion 11B and / or the outer peripheral portion 11C are formed. By separating from the glass substrate portion 11A, it is possible to substantially omit the chamfering (chamfering) step.

The glass substrate 11 thus produced by the direct press is then subjected to a reheat press. Here, when manufacturing a flat ring-shaped glass substrate, the glass substrate 11 is
For example, from the flat plate shape of FIG. 2A or the trapezoidal shape of FIG. 2B to the trapezoidal shape of FIG.
3B is pressed from the flat plate shape or the wedge shape of FIG. 3C to the wedge shape of FIG.

It is needless to say that a reheat press for improving dimensional accuracy from the flat plate shape of FIG. 2A to a similar flat plate shape is also suitably adopted, and as shown in FIG. The trapezoidal glass substrate 1 shown in FIG.
It is also preferable to form a trapezoidal wedge having a notch 13 at the boundary between the inner hole 11B and the outer peripheral portion 11C and the glass substrate 11A in FIG. Thus, similarly to the glass substrate 11, the glass substrate 12A, the inner hole portion 12B, the outer peripheral portion 12C, the notch 13, and the chamfer 14 are formed on the glass substrate 12.

Here, the upper and lower dies 8 and 9 used in the reheat press are heated and maintained at a temperature high enough to soften the glass substrate 11 once formed by the direct press under the pressure of the reheat press. Need to be For this reason, in the reheat press step, the glass substrate 11 to be treated is placed on the lower die 8 for reheat press maintained at a predetermined reheat press temperature, and the upper die 9 for reheat press also maintained at a predetermined temperature. Is pressed to press the glass substrate 11, and then the formed glass substrate 12 is moved to a predetermined position using the transfer arm 10 to be gradually cooled.

The upper and lower press dies used for forming the glass substrates 11 and 12 having various shapes shown in FIGS. 2 and 3 described above may be either a direct press process or a reheat press process. Instead, either a trapezoidal shape or a wedge shape, or one of the trapezoidal shapes and the other is a wedge shape is suitably adopted. So, for example,
One surface of the glass substrate may be trapezoidal, and the other surface may be wedge-shaped, and there is no restriction on which shape of the upper and lower molds is used.

The trapezoidal mold in the press upper and lower molds is used for producing the trapezoidal glass substrates 11 and 12, and the shape of the press surface is complementary to the trapezoidal glass substrates 11 and 12. Needless to say, Therefore, the trapezoidal press surface is formed by the glass substrate portions 11A and 1A of the trapezoidal glass substrates 11 and 12.
2A and a deep groove for forming the inner holes 11B and 12B.
B and shallow groove portions forming the outer peripheral portions 11C and 12C, and a portion where the chamfer 14 is formed between these groove portions.

The flat plate type and the wedge type in the press upper and lower molds are also defined in the same manner as the trapezoidal mold, and therefore,
The flat press surface has a deep groove forming the glass substrate portions 11A and 12A, a shallow groove forming the outer peripheral portions 11C and 12C, and a portion where the chamfer 14 is formed between these grooves. The wedge-shaped press surfaces are formed between the glass substrate portions 11A and 12A and the inner hole portions 11B and 12B in the grooves forming the glass substrate portions 11A and 12A, the inner hole portions 11B and 12B, and the outer peripheral portions 11C and 12C. There is a convex portion that forms a notch 13 between the glass substrate portions 11A and 12A and the outer peripheral portions 11C and 12C.

As the combination of the upper and lower press dies used in the direct press step and the subsequent reheat press step, various combinations shown in Table 1 can be mentioned. In the process, it is a flat plate type, in a reheat press process, in a trapezoidal shape or a wedge shape, or in a direct press process, in a trapezoidal shape, in a reheat press process, in a trapezoidal shape or a flat plate type, or in a direct press process. In particular, it is particularly preferable that the shape is wedge-shaped even in the reheat press step.

[0034]

[Table 1]

The upper and lower dies 1 and 5 for direct press and the upper and lower dies 8 and 9 for reheat press are preferably made of ceramics such as tungsten carbide or metal carbide or metal nitride having good thermal conductivity. Is preferably used. At present, the thickness of the glass substrate for hard disks is 0.645 mm ± 0.0% as a product.
It is required to have a shape of 03 mm, a parallelism of 6 μm or less, a flatness of 5 μm or less, and a surface roughness of 0.1 μm or less in Ra. later,
The thickness is 0.9 mm ± 0.02 mm, the parallelism is 20 μm or less, the flatness is 100 μm or less, and the surface roughness Ra is 0.
A glass having a shape of 5 μm or less and a thickness of 0.7 mm ± 0.01 mm, a parallelism of 10 μm or less, a flatness of 10 μm or less, and a surface roughness of 0.2 μm or less in Ra after reheat pressing. A substrate can be obtained.

Further, the crystallization treatment of the glass substrate
By performing in a range of about 0 ° C. to 800 ° C. in a range of about 3 hours to 12 hours, the thickness becomes 0.69 mm ± 0.01.
Thus, a glass substrate having a shape with a parallelism of 10 μm or less, a flatness of 5 μm or less, and a surface roughness Ra of 0.2 μm or less can be obtained. Finally, if the specifications required for the product are 0.645 mm ± 0.003 mm, the parallelism is 6 μm or less, the flatness is 5 μm or less, and the surface roughness is Ra and 0.1 or less, the rating of # 600 is satisfied. By precision polishing with a resin grindstone, it becomes possible to obtain a glass substrate that satisfies the required shape for the product.

As described above, in the method for manufacturing a glass substrate of the present invention, a thickness and a degree of parallelism very close to the product shape can be obtained in the press forming step of the glass substrate. The lapping process of the glass substrate surface, which was indispensable for the method of manufacturing the substrate and was a major cause of the high cost of the product, can be omitted, and the polishing allowance in the final polishing process can be made shallower than before. As a result, the processing time and the equipment cost can be reduced.

The method of forming a glass substrate according to the present method using the direct press and the reheat press described above, the upper and lower press dies 1.5, 8.9, and 9 used for the method, and the shapes of the glass substrates 11 and 12 formed thereby Is an inner hole portion 11B to be separated from the glass substrate portions 11A and 12A.
It has a close relationship with the separation method of 12B and / or the outer peripheral portions 11C and 12C.

As the method of separating the inner hole portion and the outer peripheral portion in the production of the flat ring-shaped glass substrate, that is, the method of processing the inner diameter and the outer shape, a method using an inner / outer diameter concentric cup whetstone or a separate whetstone for inner diameter processing It is preferable to use either a method using a grinding wheel for external diameter processing or a method using chill cutting. In the case of using the former method using a grinding stone, the glass substrate is preferably trapezoidal in FIG. When the glass substrate is formed into a shape and the latter method is used, the glass substrate is preferably formed as shown in FIG.
In the shape of a wedge. Hereinafter, each of these cases will be described.

FIG. 4 shows a trapezoidal glass substrate 21.
Inner and outer diameter concentric cup grindstone 22 (hereinafter simply referred to as “cup grindstone”)
That. It is explanatory drawing which shows the state processed using ().
In the cup grindstone 22, the inner grindstone 22A and the outer grindstone 22B are arranged concentrically.
2 is pressed against the glass substrate 21 while rotating, whereby the inner hole portion 21B and the outer peripheral portion 21C of the glass substrate 21 are cut from the glass substrate portion 21A.

Here, the inner hole portion 21 B and the outer peripheral portion 21
Since C is formed thinner than the glass substrate portion 21A, the processing time is shortened by a smaller cutting margin than when a single flat glass substrate is cut.
The wear of No. 2 is also reduced, and the processing cost can be suppressed. Further, since the chamfer 23 is formed at the boundary between the inner hole portion 21B and the outer peripheral portion 21C and the glass substrate portion 21A, it is not necessary to perform the chamfering again after the inner and outer diameter processing. Further, since the inner hole 21B and the outer peripheral portion 21C separated from the glass substrate 21A are obtained in a state of a lump of glass, they can be easily separated and washed, and therefore, a glass substrate is manufactured. It can be reused as a raw material at the time.

In order to enable inner / outer diameter processing with such a cup grindstone 22, a trapezoidal glass substrate 2
FIG. 5 shows the detailed shape of the upper and lower dies 31 for direct press or reheat press used in the molding of No. 1. Here, unlike the one shown in FIG. 11, the upper and lower dies 31 are directly fitted without using the glass to be processed, that is, the molten glass 2 or the glass substrate 11 after direct pressing, respectively. part,
That is, it has a contact portion 32.

That is, in the conventional press molding,
As shown in FIG. 11, since the upper and lower molds 55 and 56 for pressing are in contact with each other via the glass to be processed (molten glass 52), the thickness of the glass substrate 57 after pressing is reduced.
56 depends on the amount of glass filled, and
It is necessary to strictly control the weight of the molten glass 52 supplied to the glass 5. In contrast, in the present method,
The glass substrate 21 having a constant thickness by the contact of the upper and lower dies 31
The molten glass supplied excessively or the glass of the excess volume generated by the deformation by the reheat press is extruded into the space 33, and the outer periphery formed by the glass extruded into the space 33 Part 21
C is also formed to a constant thickness.

It is to be noted that the direct press when the amount of the supplied molten glass is too large and the reheat press of the glass substrate having a large outer peripheral portion due to the excessive amount of the supplied molten glass are also applicable. It is preferable that the space portion 33 is not completely filled so that surplus glass does not enter the contact portion 32, and is set to have a size in which a certain amount of space remains.

Thus, in the present method, the upper and lower dies 3
There is an advantage that a glass substrate 21 having high press working accuracy according to the shape accuracy of 1 can be obtained. As a result, the step of polishing the thickness of the glass substrate 21 formed in the subsequent step can be omitted, or even if polishing is performed, the polishing allowance can be made extremely thin, and the processing cost can be reduced. It becomes possible.

Next, the setting of the dimensions of each part of the upper and lower molds 31 will be described. First, the final gradient θ of the chamfer 23 is generally 45 °, but is not limited thereto. The thickness of the glass substrate 21A is determined in consideration of the thickness of the product and the processing allowance when the post-processing includes a polishing step. Further, the thickness of the inner hole 21B and the outer peripheral portion 21C is determined by the allowable width of the chamfer dimension required for the product and the inner and outer diameter machining accuracy using the cup grindstone 22 described above. Was.

In FIGS. 6A and 6B, the gradient θ of the gradient portion is set to 45 °. Here, FIG.
In (a), a position where the gradient portion is hardly processed, that is, a position where the gradient portion is deleted to a minimum, using a line AA ′ which is a boundary between the inner hole portion 21B or the outer peripheral portion 21C and the glass substrate portion 21A as a reference line. The distance between the reference line AA ′ and the reference line AA ′ is defined as the minimum value Amin of the processing, and the distance between the position where a large portion of the slope is deleted and the reference line AA ′ is defined as the maximum value Amax of the processing. On the other hand, as shown in FIG. 6B, a boundary line BB ′ between the inclined portion and the flat portion in the glass substrate portion 21A.
, The distance between the shortest chamfer standard position and the reference line BB ′ among the allowable dimensions of the chamfer required as a product is Cmin, while the distance between the longest chamfer standard position and the reference line BB ′ is Let the distance be Cmax.

Assuming that the thickness of the inner hole portion 21B or the outer peripheral portion 21C is Th and the maximum thickness of the chamfer portion, that is, the thickness of the flat plate portion is Tc, (Tc−Th) / 2 = Cmax + Amin = Cmin +
Amax holds. Here, when the thickness of the inner hole portion 21B and the outer peripheral portion 21C in each of the upper and lower dies 31 is T2, Th = 2 × T2, so that T2 = Tc / 2− (Cmax + Amin) = Tc / 2− (Cmin + Amax), that is, T2 is determined depending on the allowable width of the chamfer dimension of the product and the machining accuracy of the inner and outer diameters.

The dimensions R 2 and R 3 of the upper and lower molds 31 that determine the radius and the inner diameter of the glass substrate 21 are determined by the standard dimensions of the product. The outer radius R 1 of the portion of the upper and lower molds 31 that can be filled with glass is It is determined by the variation in the amount of glass supplied to the upper and lower dies 31. That is, the volume of the space 33 is (the maximum value of the glass supply amount) − (the minimum value of the glass supply amount).
/ Glass density <2 × (R1 ² −R2 ² ) × π × T2, whereby the outer radius R1 can be determined. In this case, the space 3
The radial length E of No. 3 is obtained from the difference between R1 and R2.

Subsequently, FIG. 7 shows a wedge-shaped glass substrate 2.
4 is an explanatory diagram showing a state in which No. 4 is processed by chill cut. Here, FIG. 7 is a cross-sectional view in the radial direction of the glass substrate 24. The glass substrate 24 has a trapezoidal wedge shape in which a notch 25 is formed in the trapezoidal glass substrate 21 described above. Note that the chamfer 26 is also formed on the glass substrate 24.

The chill cut is a method in which a cooled metal or the like is brought into contact with a glass substrate heated to a high temperature, and the glass is cut into a predetermined size by utilizing thermal strain generated there. There is an advantage that machining can be performed in a short time as compared with the inner / outer diameter machining method using.
Thus, in FIG. 7, at the notch 25 provided on the glass substrate 24, the metal jig 27 having the cooled concentric inner diameter processing blade 27 </ b> A and the outer diameter processing blade 27 </ b> B is brought into contact to apply a thermal shock to the notch 25. , Notches 25, causing cracks in inner hole 24 </ b> B and outer peripheral portion 2.
4C is separated from the glass substrate 24A. Therefore,
Since the method of performing chill cutting needs to be performed while the glass substrate 24 is being heated, it is performed at any stage after the direct press, after the reheat press, or during the slow cooling step after the reheat press. be able to.

FIG. 8 shows an example of the upper and lower molds 35 used for producing a glass substrate having a shape suitable for chill cutting, such as the glass substrate 24. As the upper and lower molds 35, it is common to use those having the same shape facing each other, and it is preferable that the upper and lower molds 35 have various glass substrate shapes shown in FIG. 2 or FIG. A mold having a shape in which one surface is a flat plate, or a mold in which the shapes of these molds are combined may be used.

The upper and lower molds 35 are the upper and lower molds 31 used for manufacturing the trapezoidal glass substrate 21 shown in FIG.
It has the same features as. Further, the upper and lower molds 35 are provided with contact portions 36 which are in contact with each other without the glass substrate 24 interposed therebetween.
Therefore, since the processing accuracy for keeping the thickness G between the deep portions of the opposed notches 25 formed on both surfaces of the glass substrate 24 constant is maintained, the inner and outer diameter processing shapes in the chill cut are also controlled to be constant. Becomes possible.

As described above, for the glass substrate on which the inner and outer diameter processing by the cup grindstone 22 or the chill cut is completed, if the glass substrate material is crystallized glass, a crystallization process is subsequently performed. Since the crystallization process causes a slight change in the volume of the glass substrate, the volume change causes the concentricity processing of the inner and outer diameters of the final glass substrate (hereinafter referred to as “concentricity processing”). )
In order not to increase the machining allowance in
Alternatively, it is preferable to set inner and outer diameter processing positions by chill cut. If the glass substrate material does not require crystallization, concentricity processing is performed after inner and outer diameter processing.

The concentricity processing is a step of finishing the concentricity with higher precision while grinding with a fine grindstone so that the edge of the processing end face formed by the cup grindstone 22 or the chill cut does not stand. Accordingly, an end surface polishing step is added by a nylon brush using cerium oxide as an abrasive. Finally, both surfaces of the glass substrate are finely polished so as to satisfy the glass substrate characteristics required for the product, thereby producing a glass substrate as a product, that is, a substrate. As a method of fine polishing, # 60
Using a 0 resin whetstone, 1000 rpm to 5000 r
It is preferable that the rotation is performed at a rotation speed of pm.

FIG. 9 is a flowchart showing the above-described method for manufacturing a glass substrate according to the present invention, and the process up to the completion of a substrate as a product is extremely shortened as compared with FIG. In addition, the processing time is the longest during the manufacturing process of the glass substrate, and the lapping process which increases the equipment cost is omitted. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0057]

(Example 1) SiO ₂ was used as molten glass.
There 77wt%, Al ₂ O ₃ is 5wt%, Li ₂ O is 5wt
%, The balance being SiO ₂ —Al ₂ O ₃ —L
i ₂ O-based glass was used. This glass was melted at 1400 ° C. in a glass melting furnace, and was extruded from a nozzle held at 1300 ° C. into a lower die for direct press which gave a trapezoidal glass substrate shown in FIG. 5 preheated to 600 ° C. . At this time, the molten glass extruded by the shear provided near the nozzle end was cut so that the weight of the molten glass supplied to the lower mold became about 15 g.

Subsequently, the molten glass was heated to 120 kg / cm by an upper die for direct press preheated to 600 ° C.
Pressing was performed for about 1 second at ² , and a direct press was performed. Usually, the glass substrate after direct pressing is sent to the next step, a reheat pressing step, without cooling, but according to another test, the glass substrate formed at this stage has a thickness of 0.9 mm ± 0.02 mm. It was confirmed that the parallelism was finished to 20 μm or less.

Next, after direct pressing, the upper die is removed from the formed glass substrate, and the glass substrate is transferred to the lower die for reheat pressing by the transfer arm. Here, as the lower die for the reheat press, similarly to the upper and lower dies for the direct press, one having a shape that gives a trapezoidal glass substrate is used, the preheating temperature is set to 700 ° C., and similarly, 700 ° C.
The glass substrate was subjected to press molding at a pressure of 30 kg / cm 2 for 9 seconds using an upper mold for reheat press preheated to ° C.

After removing the upper mold, the glass substrate after the reheat press was transferred from the lower mold for the reheat press to the annealing furnace set at 450 ° C. by the transfer arm. In this way, the glass substrate which has been gradually cooled has a thickness of 0.7 mm ± 0.01 mm and a parallelism of 10 μm or less at this stage. Next, the glass substrate is subjected to inner and outer diameter processing using an inner and outer diameter concentric cup grindstone to separate an inner hole portion and an outer peripheral portion, and has an inner diameter of 23.8 mm ± 0.15 mm and an outer diameter of 8 mm.
Finished to 5.2 mm ± 0.15 mm.

Further, the glass substrate is crystallized at 770 ° C. for 4 hours in a nitrogen atmosphere to have a thickness of 0.68 m.
m ± 0.01 mm, parallelism 7 μm, flatness 5 μm,
A glass substrate having a surface roughness Ra of 0.02 μm or less was obtained, and concentricity processing was performed to reduce the concentricity to 7 μm or less. Finally, the thickness was reduced to 0. 645mm ± 0.003mm, parallelism is 5μ
m, a flatness of 4 μm, and a surface roughness of 0.08 μm in Ra, satisfying the required standard as a product were obtained.

(Example 2) In the same manner as in Example 1, the molten glass was extruded by a predetermined amount into a lower die for direct press which gives the shape of a wedge-shaped glass substrate shown in FIG.
At this time, the preheating temperature of the lower mold is 600 ° C. continue,
The molten glass was pressed at 20 kg / cm ² for about 1 second by an upper die for direct press having the same shape as the lower die preheated to 600 ° C. to perform direct press.

The glass substrate after the direct press is further subjected to 30 kg / cm by the upper and lower dies for reheat press provided by the same wedge-shaped glass substrate as in the direct press.
Press molding was performed for about 9 seconds at a pressure of ² and then transferred to a slow cooling furnace set at 450 ° C. During the slow cooling, a chill cut by a cooled metal jig was applied to a notch formed in the glass substrate, and a separation between an inner hole portion and a diplomatic portion, that is, inner and outer diameter processing was performed. The dimensions of each part of the glass substrate after the slow cooling is 0.645 mm ± 0.002 mm, the parallelism is 5 μm or less, the flatness is 5 μm or less, and the surface roughness is R.
a was 0.05.

[0064]

As described above, according to the method for manufacturing a glass substrate of the present invention, the glass substrate is formed with higher precision than before, so that the post-processing step is shortened. The cost, processing consumable material cost, processing time, and the like can be greatly reduced, and as a result, an excellent effect can be achieved in that the product price of the glass substrate can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for forming a glass substrate in a method for manufacturing a glass substrate of the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a shape of a glass substrate formed by direct press in the method for manufacturing a glass substrate of the present invention.

FIG. 3 is a cross-sectional view showing one embodiment of a shape of a glass substrate formed by reheat pressing in the method for manufacturing a glass substrate of the present invention.

FIG. 4 is an explanatory diagram of inner and outer diameter processing of a glass substrate using a cup grindstone used in the method of manufacturing a glass substrate of the present invention.

FIG. 5 is an explanatory diagram relating to the shape design of the upper and lower press dies used in the method for producing a glass substrate of the present invention.

FIG. 6 is an explanatory diagram related to the design of the shape of the glass substrate chamfer according to the glass substrate manufacturing method of the present invention.

FIG. 7 is an explanatory diagram of chill cut in the method for manufacturing a glass substrate of the present invention.

FIG. 8 is another explanatory diagram related to the shape design of the upper and lower press dies used in the method for producing a glass substrate of the present invention.

FIG. 9 is a flowchart showing a method for manufacturing a glass substrate of the present invention.

FIG. 10 is a flowchart showing a conventional method for manufacturing a glass substrate.

FIG. 11 is an explanatory view showing a conventional glass substrate forming method.

[Description of Signs] 1 ... Lower mold for direct press, 2 ... Molten glass, 3 ... Shear, 4 ... Nozzle, 5 ... Upper mold for direct press, 6 ...
Suction board, 7: transport arm, 8: lower die for reheat press,
9: Upper die for reheat press, 10: Transfer arm, 11
12: glass substrate, 11A, 12A: glass substrate part, 1
1B / 12B: inner hole, 11C / 12C: outer peripheral, 13
... Notch, 14 ... Chamfer, 21 ... Glass substrate, 2
1A: glass substrate portion, 21B: inner hole portion, 21C: outer peripheral portion, 22: inner and outer diameter concentric cup grindstone (cup grindstone), 22
A: inner diameter whetstone, 22B: outer diameter whetstone, 23: chamfer, 24: glass substrate, 24A: glass substrate part, 24B
... inner hole, 24C ... outer peripheral part, 25 ... notch, 26 ... chamfer, 27 ... metal jig, 27A ... inner diameter processing blade, 27
B: Outer diameter processing blade, 31: Vertical type, 32: Contact part, 33
... space part, 35 ... vertical type, 36 ... contact part, 51 ... nozzle, 52 ... molten glass, 53 ... shear, 54 ... body type, 5
5 lower mold, 56 upper mold, 57 glass substrate.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideto Sandaiji 2-56 Sudacho, Mizuho-ku, Nagoya-shi, Aichi Japan Inside Nihon Insulator Co., Ltd.

Claims (10)

[Claims] 1. A method for producing a glass substrate, comprising a step of press-forming molten glass into a plate shape, wherein the press-forming step is obtained by a direct pressing step of solidifying and forming the molten glass into a predetermined shape; A method for producing a glass substrate, comprising: re-pressing the obtained glass substrate under heating conditions to fine-tune or deform the shape. 2. The method of manufacturing a glass substrate according to claim 1, wherein in the press forming step, an upper and lower press die having a contact portion that can be directly fitted without using a glass to be processed is used. 3. The press forming step comprises using an upper and lower press die having a space for extruding an excess volume of the glass to be processed to an outer peripheral portion of the glass to be processed. Method for producing a glass substrate. 4. The press forming step, wherein a chamfer is formed at a boundary portion between the inner hole portion and / or the outer peripheral portion and the glass substrate portion.
4. The method for producing a glass substrate according to any one of items 3 to 3. 5. The glass substrate obtained after the reheat pressing step has a trapezoidal shape in which the thickness of an inner hole portion and / or an outer peripheral portion of the glass substrate is smaller than that of the glass substrate portion. The method for producing a glass substrate according to any one of claims 1 to 4. 6. The glass substrate obtained after the reheat pressing step is formed in a wedge shape in which a notch is formed at a boundary portion between an inner hole portion and / or an outer peripheral portion of the glass substrate and the glass substrate portion. A method for producing the glass substrate according to claim 1. 7. The method according to claim 1, wherein the upper and lower molds for pressing are used in any of a trapezoidal shape, a wedge shape, or a combination of one of a trapezoidal shape and the other being a wedge shape. The method for producing a glass substrate according to any one of the preceding claims. 8. The combination of the upper and lower press dies used in the direct press step and the subsequent reheat press step is such that the trapezoidal or wedge type for the flat type, or the trapezoidal shape for the trapezoidal type. The method for producing a glass substrate according to any one of claims 1 to 7, wherein the shape is one of a mold, the flat plate shape, and the wedge shape with respect to the wedge shape. 9. The method according to claim 6, wherein a thermal shock is applied to the notch to separate the inner hole and / or the outer peripheral portion from the glass substrate at the notch. The method for producing a glass substrate according to any one of the preceding claims. 10. A glass substrate comprising SiO ₂ —Al ₂ O
₃ -Li ₂ O system a method for manufacturing a glass substrate according to any one of claims 1-9, characterized by using a crystallized glass.