JP6931919B2 - Residual stress reduction method for glass substrate and residual stress reduction device for glass substrate - Google Patents

Description

The present invention relates to a method for reducing residual stress on a glass substrate and a device for reducing residual stress on 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 at the edge of the glass substrate has been conventionally developed. For example, in the method of reducing the residual stress of the glass substrate, slow cooling is performed after the temperature is raised. 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 at the edge 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. 22 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 reducing residual stress of a glass substrate according to the seemingly present invention includes the following steps.
◎ A laser beam scanning step that reduces the residual stress by scanning the laser beam on the part of the glass substrate where the residual stress is high.
In this method, since the portion of the glass substrate having a high residual stress is heated, the residual stress of the glass substrate integrated with a 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, if the area of the region where the residual stress is high is not extremely large, the residual stress reduction treatment can be completed within several tens of minutes, and the high residual stress usually causes fracture within several tens of minutes. Even for glass substrates, residual stress can be reduced before fracture occurs.
"The portion with high residual stress is heated" means that the glass substrate has a portion that is not heated.
“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 laser beam scanning step may scan a plurality of laser beams along a portion of the glass substrate where the residual stress is high.
In this method, the time required for the laser beam scanning step is shortened.
The laser beam scanning step may scan the laser beam along the portion 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 resin or the like 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, if the area of the region where the residual stress is high is not extremely large, the residual stress reduction treatment can be completed within several tens of minutes, and the high residual stress usually causes fracture within several tens of minutes. Even for glass substrates, residual stress can be reduced before fracture occurs.
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.

The laser beam scanning step may scan a plurality of laser beams along the portion near the end face of the glass substrate.
In this method, the time required for the laser beam scanning step is shortened.

The residual stress reducing device for a glass substrate according to another aspect of the present invention includes a laser device. The laser apparatus reduces the residual stress by scanning the laser beam on the portion of the glass substrate where the residual stress is high.
In this apparatus, since the portion of the glass substrate having a high residual stress is heated, the residual stress of the glass substrate integrated with a 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, if the area of the region where the residual stress is high is not extremely large, the residual stress reduction treatment can be completed within several tens of minutes, and the high residual stress usually causes fracture within several tens of minutes. Even for glass substrates, residual stress can be reduced before fracture occurs.

The laser apparatus may scan a plurality of laser beams along a portion of the glass substrate where the residual stress is high.
In this device, the time required for the laser beam scanning step is shortened.
The laser apparatus may scan the laser beam along the portion near the end face of the glass substrate.
In this device, 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 resin or the like 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, if the area of the region where the residual stress is high is not extremely large, the residual stress reduction treatment can be completed within several tens of minutes, and the high residual stress usually causes fracture within several tens of minutes. Even for glass substrates, residual stress can be reduced before fracture occurs.

The laser apparatus may scan a plurality of laser beams along a portion near the end face of the glass substrate.
With this device, the time required for laser beam scanning is shortened.

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. 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, according to the present invention, if the area of the region where the residual stress is high is not extremely large, the residual stress reduction treatment can be completed within several tens of minutes, and the high residual stress usually causes fracture within several tens of minutes. Residual stress can be reduced even for a glass substrate in which the above occurs before the fracture occurs.

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 a reference experiment. The schematic plan view which shows the variation of the shape of the laser spot S when carrying out a reference experiment. Schematic plan view showing variations in the shape of the laser spot S when conducting a reference experiment 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. 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 reducing the residual stress by heating a portion of the glass substrate G having a high residual stress.

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 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 As an example of processing in which residual stress is generated in the glass substrate G, an operation of melting chamfering the end face of the glass substrate G will be described with reference to FIGS. 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.

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.

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. 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 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 residual stress reduction treatment of FIG. 8, an Er fiber laser was used, and the spot size was 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 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 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 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 residual stress reduction treatment of FIG. 10, 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 0.4 mm, 4 mm / s, and a laser output of 4 to 6 W. In the case of a laser output of 4 W, no change was observed in the residual stress generated by the 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 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 was set high until the glass substrate was melted and deformed, the residual stress generated by the melt chamfer was hardly reduced, and the residual stress increased significantly in a part of the region where the residual stress was low by the melt chamfer. ..
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 residual stress reduction treatment was 0.2 mm / s in the first experimental example and 1 mm / s in the second experimental example, both of which gave good results. Obtained. 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 present inventors have also conducted the experiments described below to reach the present invention. In the experiment described below, 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. bottom. 13, 14 and 15 are schematic plan views showing variations in the shape of the laser spot S when heating is performed for a predetermined time.

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. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, 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 is also applied when melt chamfering is not performed.
The present invention is also applied when the residual stress generation region is not a portion near the end face of the glass substrate G, for example, a central portion.

The present invention can be widely applied to a method for reducing residual stress on a glass substrate and a device for reducing residual stress on 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: Near the end face G: Glass substrate S: Laser spot Z: Residual stress generation region

Claims (8)

It is a method of reducing residual stress on a glass substrate.
Wherein comprising a laser beam scanning step to reduce the residual stress without melting the glass substrate by the residual stress of the glass substrate is scanned with a laser beam to a high portion, wherein the laser beam is Ru mid-infrared light der, a glass substrate Residual stress reduction method. The method for reducing residual stress on a glass substrate according to claim 1, wherein the laser beam scanning step scans a plurality of laser beams along a portion of the glass substrate having a high residual stress. The method for reducing residual stress on a glass substrate according to claim 1, wherein the laser light scanning step scans the laser light along a portion near the end face of the glass substrate. The method for reducing residual stress on a glass substrate according to claim 3, wherein the laser beam scanning step scans a plurality of laser beams along a portion near the end face of the glass substrate. It is a residual stress reduction device for glass substrates.
The glass substrate is provided with a laser device that reduces the residual stress without melting the glass substrate by scanning the laser beam on the portion of the glass substrate having a high residual stress, and the laser beam is mid-infrared light. Reduction device. The device for reducing residual stress on a glass substrate according to claim 5, wherein the laser device scans a plurality of laser beams along a portion of the glass substrate having a high residual stress. The residual stress reducing device for a glass substrate according to claim 5, wherein the laser device scans a laser beam along a portion near an end surface of the glass substrate. The residual stress reducing device for a glass substrate according to claim 7, wherein the laser device scans a plurality of laser beams along a portion near the end face of the glass substrate.

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