JP6931918B2 - Glass substrate end face treatment method and glass substrate end face treatment device - Google Patents

Description

The present invention relates to an end face treatment method for a glass substrate and an end face treatment device for a glass substrate.

In order to cut a glass substrate into product dimensions, a scribe line is formed on the glass substrate by a wheel, and the glass substrate is divided along the scribe line by bending the glass substrate (see, for example, Patent Document 1). ).
However, residual stress remains in the scribe line due to the force applied by the wheel blade and the stress applied during the break. Therefore, cracks are likely to occur naturally on the surface of the glass substrate in the horizontal direction, and the cracks further grow due to moisture or the like over time.

Further, there is known a technique for improving the strength of the end face of a glass substrate by irradiating the end face (edge) of the glass substrate with a laser beam to perform melt chamfering (see, for example, Patent Document 2). In this melt chamfering, fine cracks on the edge of the substrate disappear and the end face strength is improved.
However, in this method, residual stress is generated in the vicinity of the molten portion. Then, the residual stress increases the possibility that the substrate will crack. Specifically, the possibility of internal defects growing over time and fracture due to subsequent scratches increases, and fracture may occur within several tens of minutes depending on the magnitude of residual stress.

Japanese Unexamined Patent Publication No. 6-144875 Japanese Patent No. 5245819

In consideration of the above, a method for reducing the residual stress on the end face of the glass substrate has been conventionally developed. For example, in the method for reducing residual stress of a glass substrate, slow cooling is performed after raising the temperature. Specifically, first, the entire glass substrate is uniformly heated to a temperature equal to or higher than the glass transition point, then it is held for a certain period of time, and finally it is slowly cooled to room temperature. Generally, it takes several hours or more for the heating, holding, and slow cooling steps.
This method has an advantage that the residual stress on the end face of the glass substrate can be almost completely removed. In addition, there is an advantage that a plurality of glass substrates can be processed simultaneously in the furnace.

However, since the entire substrate is heated above the glass transition point, it cannot be applied to glass products integrated with a material having low heat resistance such as resin. FIG. 46 shows a glass product in which resin materials P1 and P2 are integrally formed on a glass substrate G.
Further, since it takes several hours or more for one residual stress reduction process, it is not possible to reduce the residual stress immediately after the residual stress is generated. Therefore, it is difficult to apply it to a glass substrate having a high probability of fracture within several tens of minutes due to high residual stress.

A first object of the present invention is to make it possible to reduce the residual stress of a glass substrate integrated with a material having low heat resistance such as resin.
A second object of the present invention is to make it possible to reduce the residual stress before the fracture occurs even for a glass substrate which is usually fractured within several tens of minutes due to a high residual stress.

Hereinafter, a plurality of aspects will be described as means for solving the problem. These aspects can be arbitrarily combined as needed.

The method for treating the end face of the glass substrate according to the seemingly present invention is a method for treating the end face after cutting the glass substrate, and has the following steps.
◎ Melting chamfering step to melt chamfer the end face of the glass substrate.
◎ Residual stress reduction step that reduces residual stress by heating the part near the end face of the glass substrate.
In this method, since the portion near the end face of the glass substrate is heated, the residual stress of the end face of the glass substrate integrated with the material having low heat resistance such as resin can be reduced. This is because the entire glass substrate is not heated, so that the resin and the like are less likely to be affected by heat.
Further, in this method, by heating the glass substrate for about 1 picosecond to 100 seconds, the residual stress is reduced in the heating region, so that even a glass substrate that normally breaks within several tens of minutes is broken. Residual stress can be reduced before
The "end face near portion" is a portion corresponding to the end face and its vicinity.
"The portion near the end face is heated" means that there is a portion that is not heated on the center side of the portion near the end face.
“Reducing the residual stress” means that the growth of internal defects over time is suppressed, and the residual stress is reduced to the extent that the glass substrate to which no external force is applied does not crack within a predetermined time.
The residual stress reducing means is, for example, a device capable of partial heating, and the heat source for performing partial heating is, for example, a laser or various heaters.
The residual stress reduction step may be started in the middle of the melt chamfering step, and both steps may be performed at the same time thereafter. Alternatively, the residual stress reduction step may be started after the melt chamfering step is completed.

The residual stress reduction step may include a laser beam scanning step for scanning the laser beam along the end face in a portion near the end face of the glass substrate.

The residual stress reduction step may include a laser beam irradiation step of irradiating each of a plurality of locations near the end face of the glass substrate with the laser beam.

In the laser beam irradiation step, a plurality of laser beams may be repeatedly irradiated to a plurality of locations at the same time or in a short time.

The end face treatment device for a glass substrate according to another aspect of the present invention is a device for treating the end face after cutting of the glass substrate, and includes a melt chamfering device and a residual stress reducing device.
The melt chamfering device melt chamfers the end face of the glass substrate.
The residual stress reducing device heats a portion near the end face of the glass substrate to reduce the residual stress.
In this device, since the portion near the end face of the glass substrate is heated, the residual stress in the portion near the end face of the glass substrate integrated with the material having low heat resistance such as resin can be reduced. This is because the entire glass substrate is not heated, so that the resin and the like are less likely to be affected by heat.
Further, in this device, by heating the glass substrate for about 1 picosecond to 100 seconds, the residual stress is reduced in the heating region, so that even a glass substrate that normally breaks within several tens of minutes is broken. Residual stress can be reduced before

The residual stress reducing device may scan the laser beam along the end face in the vicinity of the end face of the glass substrate.

The residual stress reducing device may irradiate each of a plurality of locations near the end face of the glass substrate with laser light.

The residual stress reducing device may repeatedly irradiate a plurality of laser beams at a plurality of locations at the same time or in a short time.

According to the present invention, the residual stress of a glass substrate integrated with a material having low heat resistance such as resin can be reduced.
Further, according to the present invention, even for a glass substrate which is usually broken within several tens of minutes due to high residual stress, the residual stress can be reduced before the failure occurs. This is because the residual stress is reduced in the heating region by heating the glass substrate for about 1 picosecond to 100 seconds.

The schematic diagram of the laser irradiation apparatus of 1st Embodiment of this invention. The schematic diagram of the glass substrate which shows the movement of a laser spot. A cross-sectional photograph of a glass substrate that has been melt-chamfered. The graph which shows the change of the retardation from the end face of the melt chamfered glass substrate toward the center side. The schematic plan view which shows the part where the residual stress of a glass substrate is high. The schematic cross-sectional view which shows the part where the residual stress of a glass substrate is high. The schematic diagram of the glass substrate which shows the movement of a laser spot. A graph for comparing the change in retardation from the end face of the melt-chamfered glass substrate toward the center side before and after the residual stress reduction treatment. A graph for comparing the change in retardation from the end face of the melt-chamfered glass substrate toward the center side before and after the residual stress reduction treatment. A graph for comparing the change in retardation from the end face of the melt-chamfered glass substrate toward the center side before and after the residual stress reduction treatment. Simulation results showing the temperature distribution when the scanning speed is different in the residual stress reduction process. Simulation results showing the temperature distribution when the scanning speed is different in the residual stress reduction process. The schematic plan view which shows the variation of the shape of the laser spot S when carrying out 2nd Embodiment. The schematic plan view which shows the variation of the shape of the laser spot S when carrying out 2nd Embodiment. The schematic plan view which shows the variation of the shape of the laser spot S when carrying out 2nd Embodiment. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of the laser spot of 2nd Embodiment. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic plan view which shows an example of the order of heating positions. The schematic plan view which shows an example of the order of heating positions. The schematic diagram of the laser irradiation apparatus of the modification of 2nd Embodiment. The schematic diagram of the glass substrate which shows the movement of the laser spot of 3rd Embodiment. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. The schematic diagram of the glass substrate which shows the movement of a laser spot. Schematic plan view showing variations in the spacing of heating regions. Schematic plan view showing variations in the spacing of heating regions. The schematic diagram which shows the branching of a laser spot using a diffractive optical element or a transmission type spatial light modulator. The schematic diagram which shows the branching of a laser spot using a reflection type spatial light modulator. The schematic diagram which shows the beam formation by a cylindrical lens. The schematic diagram which shows the beam formation by a galvano scanner. The schematic diagram which shows the beam formation by a polygon mirror. The schematic plan view which shows the positional relationship between a shielding plate and a glass substrate. The schematic front view which shows the positional relationship between a shielding plate and a glass substrate. The schematic plan view of the laser irradiation apparatus of the 2nd modification of 3rd Embodiment. Schematic front view of the laser irradiation device. The schematic diagram which shows the formation of the beam of 3 points using a galvano scanner. A graph showing changes in laser pulse and ray angle over time. Schematic plan view of a conventional glass product integrated with a material with low heat resistance.

1. 1. First Embodiment (1) Laser Irradiation Device FIG. 1 shows the overall configuration of the laser irradiation device 1 according to one embodiment of the present invention. FIG. 1 is a schematic view of the laser irradiation device according to the first embodiment of the present invention.
The laser irradiation device 1 has a function of melting and chamfering the end face of the glass substrate G and a function of reducing the residual stress of the portion near the end face by heating the portion near the end face of the glass substrate G.

The glass substrate G includes one made of only glass and one in which other members such as resin are combined with glass. Typical examples of the types of glass include soda glass and non-alkali glass used for displays and instrument panels, but the types are not limited to these. Specifically, the thickness of the glass is 3 mm or less, for example, in the range of 0.004 to 3 mm, preferably in the range of 0.2 to 0.4 mm.
The portion near the end face means a portion near the end face and the portion near the end face, and includes a portion near the end face of the outer peripheral edge and a portion near the end face at the edge of the hole.

The laser irradiation device 1 includes a laser device 3. The laser device 3 includes a laser oscillator 15 for irradiating the glass substrate G with laser light, and a laser control unit 17. The laser control unit 17 can control the drive of the laser oscillator 15 and the laser power.
The laser device 3 has a transmission optical system 5 that transmits laser light to the mechanical drive system side, which will be described later. The transmission optical system 5 includes, for example, a condenser lens 19, a plurality of mirrors (not shown), a prism (not shown), and the like.
The laser irradiation device 1 has a drive mechanism 11 that changes the size of a spot of laser light by moving the position of the lens in the optical axis direction.

The laser irradiation device 1 has a processing table 7 on which the glass substrate G is placed. The processing table 7 is moved by the table drive unit 13. The table drive unit 13 has a moving device (not shown) that moves the machining table 7 in the horizontal direction with respect to the head (not shown). The moving device is a known mechanism having a guide rail, a motor, and the like.

The laser irradiation device 1 includes a control unit 9. The control unit 9 has a processor (for example, a CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.), and various interfaces (for example, an A / D converter, a D / A converter, a communication interface, etc.). It is a computer system. The control unit 9 performs various control operations by executing a program stored in the storage unit (corresponding to a part or all of the storage area of the storage device).
The control unit 9 may be composed of a single processor, or may be composed of a plurality of independent processors for each control.

The control unit 9 can control the laser control unit 17. The control unit 9 can control the drive mechanism 11. The control unit 9 can control the table drive unit 13.
Although not shown, the control unit 9 is connected to a sensor for detecting the size, shape, and position of the glass substrate G, a sensor and a switch for detecting the state of each device, and an information input device.

(2) Melt chamfering operation The operation of melting chamfering the end face of the glass substrate G will be described with reference to FIGS. 2 to 4. FIG. 2 is a schematic view of a glass substrate showing the movement of a laser spot. FIG. 3 is a cross-sectional photograph of a glass substrate that has been melt chamfered. FIG. 4 is a graph showing the change in retardation from the end face of the melt-chamfered glass substrate toward the center side.

First, the glass substrate G is set at a predetermined position on the processing table 7.
Next, as shown in FIG. 2, the glass substrate G is irradiated with a laser beam to the portion 21 near the end face of the glass substrate G, and the laser spot S is further scanned along the end face 20 of the glass substrate G. At this time, the laser spot S is set so as to be at a position, for example, 10 μm to 150 μm away from the end surface 20 of the glass substrate G toward the inside (center side) of the substrate.

By irradiating and scanning the laser spot S as described above, the portion 21 near the end face of the glass substrate G is heated. In particular, by irradiating the laser beam of mid-infrared light, the laser beam is absorbed while being transmitted to the inside of the glass substrate G. Therefore, the end surface 20 of the glass substrate G is heated relatively uniformly not only on the front surface side which is the irradiation surface of the laser beam but also on the entire inside and the back surface side of the glass substrate G. Therefore, the end face 20 of the glass substrate G is melted so that the central portion of the substrate thickness bulges outward, and as a result, the end face 20 is chamfered as shown in FIG.

However, the method of melt chamfering is not particularly limited. As another example, the laser beam is irradiated from both or one of the front surface and the back surface of the glass substrate G, and the laser beam is irradiated from the direction orthogonal to the end surface 20 of the glass substrate G to make the end surface 20 of the glass substrate G. It may be melted and chamfered. You may irradiate a laser beam of far infrared light.
As a result of the above, as shown in FIG. 4, the retardation (nm) is high in the portion near the end face of the glass substrate G (for example, the region of the end face 20 to 200 μm). The retardation is a phase difference generated in the light transmitted through the object, and is a value proportional to the stress acting in the object. High retardation of an object to which no external force is applied means high residual stress.

(3) Residual stress reduction treatment The residual stress reduction treatment for heating the portion near the end face of the glass substrate G will be described with reference to FIGS. 5 to 7. FIG. 5 is a schematic plan view showing a portion of the glass substrate where the residual stress is high. FIG. 6 is a schematic cross-sectional view showing a portion of the glass substrate where the residual stress is high. FIG. 7 is a schematic view of a glass substrate showing the movement of the laser spot.

As shown in FIG. 7, the glass substrate G on the processing table 7 is irradiated with a laser beam to the portion 21 near the end face of the glass substrate G, and the laser spot S is further applied along the portion 21 near the end face of the glass substrate G. And scan. The portion 21 near the end face here corresponds to the residual stress generation region Z (hatched region) in which the residual stress is generated by the melt chamfering.
At this time, the laser spot S is smaller than the glass substrate G, and is set to a size of, for example, about 4 μm to 20 mm. As a result, the portion 21 near the end face of the glass substrate G is heated by the laser spot S.

The present inventors have found that in the residual stress reduction treatment, it is necessary to suppress the region where the temperature becomes high to a narrow range in the direction along the end face 20, and have arrived at the present invention. The grounds for this will be described later. That is, the scanning speed of the laser spot S is set to be slow, and the glass substrate G is heated to a temperature equal to or higher than the glass transition point. As a result, the high temperature region does not expand in the direction along the end face 20, and therefore the effect of reducing the residual stress is enhanced. Conversely, setting a faster scanning rate increases the output required to heat above the glass transition point. When the high-power laser spot S is scanned at a high speed, the high-temperature region expands in the direction along the end face 20, and as a result, the effect of reducing the residual stress becomes low.
The scanning speed may be 20 mm / s or less, preferably 10 mm / s or less, and more preferably less than 5 mm / s.

As a result of the above, the portion 21 near the end face of the glass substrate G (that is, the residual stress generation region Z) is heated to the glass transition point or higher, and as a result, the residual stress is reduced.
In this method, the portion 21 near the end face of the glass substrate G is heated (that is, the entire glass substrate G is not heated), so that the portion near the end face of the glass substrate G integrated with a material having low heat resistance such as resin is heated. The residual stress of 21 can be reduced. This is because the resin and the like are less likely to be affected by heat. Further, if the area of the residual stress generation region Z is not extremely large, the residual stress reduction treatment can be completed within several tens of minutes, and the glass substrate which is usually broken within several tens of minutes due to the high residual stress. However, the residual stress can be reduced before the fracture occurs.

The type (wavelength) of the laser is not particularly limited.
The required laser output is an output that can heat the glass substrate G to the glass transition point or higher. Therefore, when a laser having a low light absorption rate for glass is used, a higher laser output is required.
Further, the heat source is not limited to the laser, and may be, for example, an infrared heater or a contact heater.
When the temperature of the heating portion of the glass substrate G is about the glass transition point, deformation of the heating portion is hardly confirmed. When the temperature of the heating portion is higher, the heating portion melts and the shape changes. The higher the laser output, the lower the viscosity of the heated part, and the greater the deformation in a short time. According to the present invention, the residual stress is reduced even when the laser output is high and the shape of the glass substrate G is deformed. However, when the present invention is applied to a product in which the allowable amount of deformation of the glass substrate G is limited, the upper limit of the laser output is set so that the viscosity of the glass substrate G does not decrease and the amount of deformation does not exceed the allowable value. Should be set.

The direction of heat input to the glass substrate G is not particularly limited. The heat may be input from the front surface of the glass substrate G, the heat may be input from the back surface, or the heat may be input from the end surface 20.
In the above embodiment, the residual stress reduction treatment is performed after the melt chamfering is completed, but the melt chamfering treatment and the residual stress reduction treatment may be performed in parallel on one glass substrate G. Specifically, by using two laser beams, the residual stress reduction treatment is started in the middle of the melt chamfering operation, and after that, both treatments are performed at the same time. In that case, the total processing time is shortened.
In order to use a plurality of laser beams, a plurality of laser oscillators may be prepared, or the laser beam may be branched from one laser oscillator.

(4) Experimental Example An experimental example of residual stress reduction processing by laser scanning will be described with reference to FIGS. 8 to 10. 8 to 10 are graphs for comparing the change in retardation from the end face of the melt-chamfered glass substrate (non-alkali glass having a thickness of 200 μm) toward the center side before and after the residual stress reduction treatment. ..
The residual stress reduction treatment was possible with either a mid-infrared laser (Er fiber laser) or a far-infrared laser (CO _{2 laser).} The specifications of the Er fiber laser are a wavelength of 2.8 μm, a maximum output of 10 W, a light absorption rate of about 30%, and a real heat input of a maximum of 3 W. The specifications of the CO ₂ laser are a wavelength of 10.6 μm, a maximum output of 250 W, a light absorption rate of about 80%, and a real heat input of a maximum of 200 W.

(4-1) First Experimental Example In the first heating (melt chamfering) of FIG. 8, an Er fiber laser was used, and the spot size was 200 μm, 5 W, and 3 mm / s.

In the second heating (residual stress reduction treatment) of FIG. 8, an Er fiber laser was used, and the substrate subjected to melt chamfering under the above conditions was heated under the conditions of a spot size of 2 mm, 4 W, and 0.2 mm / s.
As is clear from FIG. 8, the maximum value of the residual stress is significantly reduced.

(4-2) Second Experimental Example In the first heating (melt chamfering) of FIG. 9, an Er fiber laser was used, and the spot size was 200 μm, 5 W, and 3 mm / s.
In the second heating (residual stress reduction treatment) of FIG. 9, an Er fiber laser was used, and the substrate subjected to melt chamfering under the above conditions was heated under the conditions of a spot size of 1 mm, 3.5 W, and 1 mm / s. As is clear from FIG. 9, the maximum value of the residual stress is reduced.

In both the experimental examples of FIGS. 8 and 9, before the residual stress reduction treatment was performed, the melt-chamfered glass substrate had a high probability of spontaneously cracking within a few minutes to a few days, whereas it remained. After the stress reduction treatment, it did not crack even after 1 month. In the residual stress reduction treatment, the power density of the laser beam is adjusted so that the glass does not melt and change its shape. That is, the residual stress was reduced and the probability that the glass substrate was spontaneously cracked was reduced without changing the shape of the end face of the glass substrate that had been melt-chamfered.

(4-3) Third Experimental Example In the first heating (melt chamfering) of FIG. 10, an Er fiber laser was used, and the spot size was 200 μm, 5 W, and 3 mm / s.
In the second heating (residual stress reduction treatment) of FIG. 10, an Er fiber laser was used, and a substrate subjected to melt chamfering under the above conditions was subjected to conditions of a spot size of 0.4 mm, 4 mm / s, and a laser output of 4 to 6 W. It was heated. In the case of a laser output of 4 W, no change was observed in the residual stress generated by the first heating (melt chamfering). This is because the laser output is low and the temperature of the glass substrate G does not exceed the glass transition point. In the case of a laser output of 5.5 W, the maximum value of residual stress was slightly reduced. In addition, the residual stress increased significantly in a part of the region where the residual stress was low in the first heating (melt chamfering). In the case of a laser output of 6 W, the glass substrate G was melted and deformed as a result of the high laser output. Even if the laser output is set high until the glass substrate melts and deforms, the residual stress generated by the first heating (melt chamfering) is hardly reduced, and the residual stress is low in the first heating (melt chamfering). The residual stress increased significantly in a part of.
As can be seen from FIG. 10, in this experimental example, the residual stress reduction effect was low even if the laser output was adjusted.

(4-4) Discussion As described above, the scanning speed of the second heating (residual stress reduction treatment) is 0.2 mm / s in the first experimental example and 1 mm / s in the second experimental example. Good results were obtained for both. However, as can be seen from the comparison of the graphs, the faster the scanning speed, the lower the residual stress reduction effect. In the third experimental example, as a result of setting the scanning speed to 4 mm / s, the residual stress was hardly reduced. From the above, in the case of the laser scanning method of the present embodiment, it is preferable that the scanning speed is slow. Specifically, the scanning speed may be 20 mm / s or less, preferably 10 mm / s or less, and more preferably less than 5 mm / s.

Based on experiments and temperature simulation of the glass substrate, the present inventors have found that it is necessary to suppress the high temperature region to a narrow range in the direction along the end face 20 in the residual stress reduction treatment. It led to the invention. The rationale for this is explained, for example, by FIGS. 11 and 12. 11 and 12 are simulation results showing temperature distributions in different scanning speeds in the residual stress reduction process.
FIG. 11 shows a case where the scanning speed of the laser spot S is as slow as 0.2 mm / s and the residual stress reducing effect is high. Since the scanning speed is set to be slow, the high temperature portion (for example, the region exceeding 300 ° C.) is not lengthened along the end face.
On the other hand, FIG. 12 shows a case where the scanning speed is as high as 20 mm / s and the residual stress reducing effect is low. However, the laser output is set high so that it is heated to the same temperature as in FIG. It can be seen that the high temperature portion is longer along the end face as compared with FIG.
These results are one of the grounds for showing that the residual stress reducing effect is reduced when the high temperature portion becomes long along the end face.

Furthermore, the second experimental example relating to the second embodiment described later also shows the grounds for reaching the present invention. In the second experimental example, instead of scanning the laser spot S along the end face near portion 21, one point in the end face near portion 21 is heated for a predetermined time to reduce the residual stress in the heated region. .. 13, 14 and 15 are schematic plan views showing variations in the shape of the laser spot S when the second embodiment is implemented.

FIG. 13 shows a circular laser spot S100 and an elliptical laser spot S101 long in the direction orthogonal to the end face 20. FIG. 14 shows long elliptical laser spots S102 and S103 along the end face 20. FIG. 15 shows a long laser spot S104 along the end face 20 that covers the entire end face 20. When the laser spots S100, S101, S102, and S103 were used, the residual stress in the heating region was reduced by adjusting the laser output and the predetermined time for heating. However, the residual stress reducing effect was higher in the order of S100≈S101>S102> S103. When the laser spot S104 was used, the residual stress was not reduced even if the predetermined time for laser output and heating was adjusted.
In view of the simulation results and experimental results shown above, the present inventors have found that in the residual stress reduction treatment, it is necessary to suppress the high temperature region to a narrow range in the direction along the end face 20. , The present invention has been reached.

(5) First Modification Example In the first embodiment, the single beam scanning process for reducing the residual stress on one side of the glass substrate G has been described, but a plurality of beams for irradiating each of a plurality of locations near the end face of the glass substrate with laser light. Residual stresses on a plurality of sides may be reduced at the same time by simultaneous scanning.
Such an embodiment will be described as a first modification with reference to FIGS. 16 to 18. 16 to 18 are schematic views of a glass substrate showing the movement of the laser spot.

As shown in FIG. 16, the residual stress generation region Z is formed in the vicinity of the end face, which is the four sides of the glass substrate G.
As shown in FIG. 17, the four laser spots S scan each of the four sides.
As a result, as shown in FIG. 18, the residual stress of the glass substrate G is reduced. In this case, the processing time is shorter than that of the single beam scanning process. The number of laser spots may be 2, 3, 5 or more.

(6) Second Modification Example In the first embodiment, the glass substrate G is a quadrangle and has a plurality of straight sides, but the present invention can also be applied to a glass substrate G having sides such as a curved line.
Such an embodiment will be described as a second modification with reference to FIGS. 19 to 21. 19 to 21 are schematic views of a glass substrate showing the movement of the laser spot.

As shown in FIG. 19, the glass substrate G is circular, and the portion near the end face, which is the entire outer peripheral edge, is the residual stress generation region Z.
As shown in FIG. 20, the four laser spots S scan each of the four outer peripheral edges in the circumferential direction. As a modification, the glass substrate G may be rotated.
As a result, as shown in FIG. 21, the residual stress of the glass substrate G is reduced.
The number of laser spots may be 2, 3, 5 or more. Further, the same method can be applied to the case where the portion 21 near the end face of the edge of the hole of the glass substrate G in which the circular hole is formed is the residual stress generation region Z.

2. 2nd Embodiment (1) Basic Principle In the 1st embodiment, the laser beam is scanned on the end face as the residual stress reduction treatment, but the irradiation method of the laser beam is not limited to this.
Other irradiation methods of the laser beam will be described as the second embodiment with reference to FIGS. 22 to 25. 22 to 25 are schematic views of a glass substrate showing the movement of the laser spot of the second embodiment. The basic configuration and basic operation of the laser irradiation device are the same as those in the first embodiment.

In FIG. 22, the laser spot S1 is irradiated to one point of the end face vicinity portion 21.
In FIG. 23, the laser spot S2 is irradiated to another point at a different position in the end face vicinity portion 21.
In FIG. 24, the laser spot S3 is irradiated to another point at a different position in the end face vicinity portion 21.
In FIG. 25, the laser spot S4 is irradiated to another point at a different position in the end face vicinity portion 21.

When a laser spot is irradiated to one point on the residual stress generation region Z for a predetermined time and heated to a temperature equal to or higher than the glass transition point, the residual stress is reduced in that region. Therefore, as is clear from FIGS. 22 to 25, by sequentially heating one point for a predetermined time, the laser spots S1 to S4 are continuously irradiated to adjacent positions in the end face direction, and as a result, the laser spots S1 to S4 are irradiated to the adjacent positions. The portion 21 near the end face is irradiated as a whole.
However, the number of laser spots, the position, the order of irradiation, and the proportion of the laser spots in the vicinity of the end face 21 are not limited to this embodiment.

In this embodiment, by repeating heating one point for a predetermined time and shifting the position and heating one point for a predetermined time, the residual stress generation region Z is set to a temperature equal to or higher than the glass transition point and is near the end face. The residual stress of the entire portion 21 is reduced.
In this embodiment, the laser spot S is finally irradiated to the entire end face vicinity portion 21 to reduce the residual stress of the entire end face vicinity portion 21. However, when the residual stress is reduced only in a part of the end face near portion 21, the laser spot S may irradiate only a specific region of the end face near portion 21, or the end face near portion 21 may be irradiated. Only about half of the whole area may be irradiated.

The predetermined time for heating depends on the temperature of the heating region during heating. That is, the higher the output, the higher the temperature in the heating region, and the shorter the residual stress is reduced. The higher the output, the shorter the predetermined time for heating and the shorter the takt time.
The predetermined time for heating is preferably, for example, about 1 picosecond to 100 seconds. The minimum predetermined time is 1 picosecond, which is known as the minimum value of the time required for structural relaxation of glass (relaxation time). The lower the temperature in the heating region, the longer the relaxation time. When the temperature in the heating region is about the glass transition point, it is preferable that the predetermined time for heating is about 100 seconds, which is the relaxation time.
In order to extremely shorten the predetermined time for heating, it is necessary to heat the glass substrate G to a high temperature in a short time, and the required output is greatly increased. Therefore, in practical use, the merit of shortening the tact time and the increase in output are obtained. The heating conditions are determined in consideration of the cost increase due to the above.

When the laser spot S is circular, it is preferable that the laser spot S has a diameter of, for example, 4 μm to 20 mm. In this second embodiment, the larger the diameter of the laser spot S, the larger the processing area per heating, and the shorter the time required to reduce the residual stress in the predetermined area. As shown in FIGS. 13 and 14, the laser spot S may be elliptical. However, the longer the width in the direction along the end face 20 of the laser spot S with respect to the width in the direction intersecting the end face 20 of the laser spot S, the lower the residual stress reduction effect. The width in the direction along the end face 20 of the laser spot S is preferably 10 times or less the width in the direction intersecting the end face 20 of the laser spot S.

The laser output needs to be a value that can heat up to the glass transition point or higher. This is appropriately set according to the size of the laser spot, the laser wavelength, the type of glass, and the plate thickness. When the temperature of the heating portion is high, the heating portion melts and the shape changes. According to the present invention, the residual stress is reduced even when the laser output is high and the shape of the glass substrate G is deformed. However, when the present invention is applied to a product in which the allowable amount of deformation of the glass substrate G is limited, the upper limit of the laser output is set so that the viscosity of the glass substrate G does not decrease and the amount of deformation does not exceed the allowable value. Should be set.
An example of conditions for heating a non-alkali glass having a thickness of 200 μm for a predetermined time will be described. _{3W, 20s using a CO 2} laser (wavelength 10.6 μm) with a spot size of 4 mm. The conditions of 4W and 4s may be used. The conditions may be 6W and 2s.
Further, the heat source is not limited to the laser, and may be, for example, an infrared heater or a contact heater.

(2) Laser spot shift irradiation method When the above predetermined time heating method is performed while shifting the position, heating is performed sequentially for a predetermined time, such as the first heating, the second heating by shifting, the third heating by shifting, and so on. It is said. At this time, in order to shorten the tact time, it is necessary to shorten the time interval between the heating operations. However, for example, in the order of the heating positions shown in FIG. 26, the region adjacent to the immediately preceding heating region is the next heating region. In this case, for example, the second heating needs to wait until the temperature of the first heating portion drops. The reason is, for example, when the second heating region is combined with the first heating region and the above-mentioned "when the high temperature portion of the case where the portion near the end face of the glass substrate G is heated becomes longer along the end face". Because it corresponds.

(2-1) First Method When the above-mentioned staggered irradiation is performed, there is a heating position order devising method as a first method for shortening the time interval between heating operations. In this method, specifically, as shown in FIG. 27, the region adjacent to the immediately preceding heating region is skipped, and the distant region is set as the next heating region.

(2-2) Second Method As a second method for shortening the time interval between heating operations, there is a substrate cooling method. FIG. 28 shows a substrate cooling device 35 that cools the substrate with jet air from the front side or the back side of the glass substrate G. FIG. 28 is a schematic view of a laser irradiation device of a modified example of the second embodiment.
In this case, the first heating region is cooled by air cooling or the like, and then the second heating is performed. As a result, the time interval can be shortened even when heating is performed in the order shown in FIG.

The reason why the time interval can be shortened as described above is that the next laser beam is irradiated after the heated portion is cooled by being irradiated with the laser beam, so that the next laser beam is in the vicinity of the previously heated portion. This is because the region that becomes hot does not expand in the direction along the end face due to cooling even if the laser is irradiated. That is, in this case, it corresponds to the above-mentioned "case where the high temperature portion of the case where the portion near the end face of the glass substrate G is heated is suppressed to be narrow along the end face".

The cooling medium for cooling is not particularly limited.
The substrate cooling device may be realized by making the table on which the glass is placed a water-cooled table.
A substrate cooling mechanism may be mounted on the laser irradiation device 1.

3. 3. Third Embodiment The predetermined time heating method of the second embodiment employs a one-point heating method in which each point is irradiated with a laser, but the laser irradiation may irradiate a plurality of points at the same time.
Such an example will be described as a third embodiment with reference to FIGS. 29 to 32. In this multi-point simultaneous irradiation method, the processing speed is substantially increased. 29 to 32 are schematic views of a glass substrate showing the movement of the laser spot of the third embodiment.

In FIG. 29, the two laser spots S1 irradiate the end face vicinity portion 21.
FIG. 30 shows a situation in which the residual stress is reduced in the portion near the end face 21 by the operation of FIG. 29.
In FIG. 31, the two laser spots S2 irradiate the end face vicinity portion 21. At this time, the two laser spots S2 are irradiated at different positions from the previous two laser spots S1, that is, they are shifted. Further, the two laser spots S2 correspond to the remaining residual stress generation region Z.
FIG. 32 shows a situation in which the residual stress is reduced in the portion near the end face 21 by the operation of FIG. 31.

In the multi-point simultaneous heating method, when the number of heating regions is n points, n times the output is required as compared with the one-point heating method of the second embodiment. Further, in the shielding method described later, a higher output is required depending on the area of the shielding portion.
The heating conditions per point are the same as in the second embodiment.

The interval between the heating regions is preferably 0.5 times or more the width of one heating region. If the spacing between the heating regions is too narrow, the plurality of heating regions will be connected, which is equivalent to irradiating one long laser spot along the end face 20. That is, the effect of reducing the residual stress is reduced in response to the above-mentioned "when the high temperature portion becomes longer along the end face in the case where the portion near the end face of the glass substrate G is heated". 33 and 34 are used to show variations in the shape and spacing of the heating regions. 33 and 34 are schematic plan views showing variations in the shape and spacing of the heating regions.
FIG. 33 shows three circular laser spots S105. The laser spot S105 has the same shape as the laser spot S100 of FIG. 13, and has a high residual stress reducing effect. Further, the interval between the laser spots S105 is set to be about the same as the width of the laser spots S105.
FIG. 34 shows three elliptical laser spots S106 that are long in the direction intersecting the end face 20. The laser spot S106 has the same shape as the laser spot S101 of FIG. 13, and has a high residual stress reducing effect. Further, the interval of the laser spots S106 is set to be about the same as the width of the laser spots S106.
There are many combinations of laser spot shapes and intervals other than the above.

The processing speed of the residual stress reduction treatment depends on the number of heating regions. For example, when the width of the heating region is 8 mm, 10 points are simultaneously heated, the heating time is 1 s, and the residual stress reduction width per heating region is 4 mm, the processing speed for one irradiation is 4 mm × 10 / 1s = 40 mm / s.

A method of simultaneously heating at multiple points using an optical branching element will be described with reference to FIGS. 35 and 36. FIG. 35 is a schematic view showing branching of a laser spot using a diffractive optical element or a transmissive spatial light modulator. FIG. 36 is a schematic diagram showing branching of a laser spot using a reflective spatial light modulator.
In FIG. 35, a diffractive optical element (DOE) 31 or a transmissive spatial light modulator (SLM) 31 is shown.
In FIG. 36, a reflective spatial light modulator (SLM) 33 is shown. Two mirrors 34 are also shown.

When the multi-point simultaneous heating method as shown in FIGS. 29 to 32 is performed while shifting the position, the heating is sequentially performed for a predetermined time, such as the first heating, the second heating by shifting, the third heating by shifting, and so on. Will be done. At this time, in order to shorten the tact time, it is necessary to shorten the time interval between the heating operations. However, for example, when any of the second heating regions at a plurality of locations is adjacent to any of the first heating regions at a plurality of locations, the temperature of the first heating portion is lowered in the second heating. You have to wait until you do. The reason is, for example, when the second heating region is combined with the first heating region and the above-mentioned "when the high temperature portion of the case where the portion near the end face of the glass substrate G is heated becomes longer along the end face". Because it corresponds.

As the first method of shortening the time interval between heating operations, in the above case, the time interval is set by devising the heating position order so that the second heating region is located away from the first heating region. Can be shortened.
As a second method for shortening the time interval between heating operations, there is a substrate cooling method. In this method, as shown in FIG. 28 of the second embodiment, a substrate cooling device 35 that cools the substrate with jet air from the front side or the back side of the glass substrate G is used. In this case, the first heating region is cooled by air cooling or the like, and then the second heating is performed. Thereby, for example, even when the second heating region becomes a region adjacent to the first heating region, the time interval can be shortened.

The reason why the time interval can be shortened as described above is that the next laser beam is irradiated after the heated portion is cooled by being irradiated with the laser beam, so that the next laser beam is in the vicinity of the previously heated portion. This is because the region that becomes hot does not expand in the direction along the end face due to cooling even if the laser is irradiated. That is, this is because it corresponds to the above-mentioned "case where the high temperature portion of the case where the portion near the end face of the glass substrate G is heated is suppressed to be narrow along the end face".
Cooling may be performed at all times, or may be performed after laser light irradiation.
Similar to the second embodiment, the configuration of the cooling device, the cooling means, and the arrangement position are not particularly limited.

(1) First Deformation Example A method of simultaneously heating multiple points by a shielding method will be described with reference to FIGS. 37 to 41. FIG. 37 is a schematic view showing beam formation by a cylindrical lens. FIG. 38 is a schematic view showing beam formation by a galvano scanner. FIG. 39 is a schematic view showing beam formation by a polygon mirror. FIG. 40 is a schematic plan view showing the positional relationship between the shielding plate and the glass substrate. FIG. 41 is a schematic front view showing the positional relationship between the shielding plate and the glass substrate.
A cylindrical lens 41 (FIG. 37), a galvano scanner 43 (FIG. 38), a polygon mirror 45 (FIG. 39), or the like forms an elongated beam along the end face 20.

Then, as shown in FIGS. 40 and 41, a plurality of laser spots S are formed by partially shielding the laser beam B using the shielding plate 47. The shielding plate 47 has a plurality of shielding portions 47a arranged with a gap in the end face direction.
The shielding plate 47 needs to reflect or absorb the laser beam. When absorbing, it is necessary to have heat resistance. If it absorbs laser light but does not have sufficient heat resistance, it is necessary to provide a forced cooling mechanism for the shielding plate.
A mechanism (not shown) for moving the shielding plate 47 along the end face portion 21 of the glass substrate G may be provided. In this case, the positions of the plurality of laser spots S can be changed, and by repeating this, the laser spots S can be irradiated to the entire end face vicinity portion 21.

(2) Second Modified Example With reference to FIGS. 42 to 45, a method of performing simultaneous heating at multiple points by a method of scanning laser light one pulse at a time will be described. FIG. 42 is a schematic plan view of the laser irradiation device of the second modification of the third embodiment. FIG. 43 is a schematic front view of the laser irradiation device. FIG. 44 is a schematic view showing the formation of three laser spots using the galvano scanner 43. FIG. 45 is a graph showing changes in the laser pulse and the ray angle with time.
As shown in FIGS. 42 and 43, the laser irradiation device 1A includes a laser oscillator 15, a beam expander 49, a condenser lens 19, and a galvano scanner 43. Then, the laser irradiation device 1A uses the galvano scanner 43 to control the irradiation position of each pulse of the laser light, and irradiates the laser light to a plurality of points at the same time in a pseudo manner to create a state in which multiple points are heated at the same time. ..

In the example of FIG. 44, the position of the laser spot is moved by 10 mm on the sample surface by changing the beam angle of the laser beam by 1 ° by the galvano scanner 43. When the light beam angle is changed in synchronization with the laser pulse oscillating at 500 Hz as shown in FIG. 45, the laser beam reciprocates once in a 20 mm region with a period of 12 milliseconds, and each of the three laser spots has one cycle (1 cycle (1 cycle). The laser beam is irradiated only for 2 milliseconds out of 12 milliseconds). Further, the region between the three laser spots is not irradiated with the laser beam. In this case, since the period in which the laser beam is scanned is sufficiently fast, if this operation is repeated for a predetermined time (for example, 1 second), the three points are simultaneously heated for a predetermined time.
In the second modification, the substrate cooling device 35 is provided as shown in FIG. 43. However, the substrate cooling device may not be provided.

4. Other Embodiments Although the plurality of embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. In particular, the plurality of embodiments and modifications described herein can be arbitrarily combined as needed.

The present invention can be widely applied to an end face treatment method for a glass substrate and an end face treatment device for a glass substrate.

1: Laser irradiation device 3: Laser device 5: Transmission optical system 7: Processing table 9: Control unit 11: Drive mechanism 13: Table drive unit 15: Laser oscillator 17: Laser control unit 19: Condensing lens 20: End face 21: End face vicinity 35: Substrate cooling device 41: Cylindrical lens 43: Galvano scanner 45: Polygon mirror 47: Shielding plate G: Glass substrate S: Laser spot Z: Residual stress generation region

Claims (8)

It is a method of treating the end face after cutting the glass substrate.
A melt chamfering step of melt chamfering the end face of the glass substrate, and
A residual stress reduction step of heating the portion near the end face of the glass substrate to reduce the residual stress,
With
The residual stress reduction step has a laser light scanning step of scanning the laser beam along the end face portion near the glass substrate on the end face, the end face processing method of the glass substrate. It is a method of treating the end face after cutting the glass substrate.
A melt chamfering step of melt chamfering the end face of the glass substrate, and
A residual stress reduction step of heating the portion near the end face of the glass substrate to reduce the residual stress,
With
The residual stress reduction step has a laser beam irradiation step of irradiating a laser beam at a plurality of positions each of said end face portion near the glass substrate, the end face processing method of the glass substrate. The end face treatment method for a glass substrate according to claim 2 , wherein the laser beam irradiation step irradiates the plurality of laser beams simultaneously or repeatedly in a short time. The method for treating an end face of a glass substrate according to any one of claims 1 to 3, wherein the laser beam is a mid-infrared laser or a far-infrared laser. A device that processes the end face of a glass substrate after cutting.
A melt chamfering device that melt chamfers the end face of the glass substrate,
A residual stress reducing device that heats the portion near the end face of the glass substrate to reduce the residual stress.
With
The residual stress reduction device scans the laser light near the end surface portions of the glass substrate along the end face, the end face processing apparatus of the glass substrate. A device that processes the end face of a glass substrate after cutting.
A melt chamfering device that melt chamfers the end face of the glass substrate,
A residual stress reducing device that heats the portion near the end face of the glass substrate to reduce the residual stress.
With
The end face treatment device for a glass substrate according to claim 5 , wherein the residual stress reducing device irradiates a plurality of locations near the end face of the glass substrate with laser light. The end face treatment device for a glass substrate according to claim 6 , wherein the residual stress reducing device irradiates the plurality of laser beams simultaneously or repeatedly in a short time. The method for treating an end face of a glass substrate according to any one of claims 5 to 7, wherein the laser beam is a mid-infrared laser or a far-infrared laser.

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