JP5292420B2 - Glass substrate scribing method - Google Patents

Description

The present invention relates to a glass substrate scribing method, and more particularly to a glass substrate scribing method for scribing tempered glass having a tempered layer formed on the surface thereof.

As a method of forming a scribe groove for dividing in a glass substrate, there is a method of forming using a laser beam. In this case, a scribe groove is formed by irradiating a laser beam along a scribe line and dissolving and evaporating a part of the substrate. However, in this method, a part of the dissolved and evaporated substrate may adhere to the surface of the substrate, which may be accompanied by deterioration of quality. In addition, the scar formed in the melted and evaporated portion causes a reduction in the strength of the substrate end face.

Then, there exists a method as shown in patent document 1 or 2 as another scribe groove | channel formation method. Here, an initial crack is formed at a location that becomes the starting point of the scribe groove of the glass substrate, and the initial crack is irradiated with laser light. As a result, thermal stress is generated in the laser irradiation portion, and the crack progresses to form a scribe groove.

Japanese Patent Laid-Open No. 3-489 JP-A-9-1370

  In the latter scribe groove forming method, the initial crack is formed by using a hard tool such as an indenter or a diamond cutter, or by irradiating a laser beam.

By the way, in the recent FPD (flat panel display) industry, since the strength of the substrate end face is regarded as important, chemically tempered glass having a tempered layer formed on the surface is mainly used as a glass substrate. This chemically tempered glass has a layer (reinforced layer) whose surface is given a compressive stress by an ion exchange treatment, and has recently been used for a cover glass such as a touch panel particularly requiring end face strength.

Such tempered glass is highly durable and hardly scratched. Therefore, it is very difficult to form an initial crack stably on the end face of the tempered glass and form a scribe groove. For example, when the depth of the initial crack is shallow, the scribe groove is not formed. On the other hand, if the initial crack is too deep, the initial crack cannot be propagated along the scribe line, and a desired scribe groove cannot be formed.

An object of the present invention is to enable a desired scribe groove to be formed relatively easily and stably with respect to a tempered glass having a tempered surface.

The scribing method for a glass substrate according to the first invention is a method for scribing tempered glass having a tempered layer having a compressive stress on its surface, and includes a first step and a second step. In the first step, an initial crack having a depth exceeding the tempered layer is formed on the surface of the tempered glass. In the second step, the initial crack is heated by irradiating the initial crack with laser light, the heated region is cooled, and the crack is advanced along the scribe line.

Here, an initial crack having a depth exceeding the tempered layer is formed on the surface of the tempered glass. Thereafter, the initial crack is irradiated with laser light and heated, and the heated region is cooled. As a result, the initial crack propagates along the scribe line.

Here, an initial crack having a depth exceeding the reinforcing layer is formed, and a desired scribe groove can be stably formed relatively easily.

The scribing method of the glass substrate according to the second invention is the scribing method of the first invention,
In the first step, the depth of the initial crack is not less than 1.14 times and not more than 1.67 times the thickness of the strengthened layer of the tempered glass.

  Here, if the depth of the initial crack is less than 1.14 times the thickness of the tempered glass tempered layer, the tempered layer remains, and the crack is not removed even if heat treatment and cooling treatment by laser light irradiation in the subsequent process are performed. However, it is difficult to form a scribe groove. On the other hand, if the depth of the initial crack exceeds 1.67 times the thickness of the reinforcing layer, the crack is not intended by heating and cooling in the subsequent process, and in a direction different from the direction in which the scribe line was formed. It progresses and it becomes difficult to form a desired scribe groove.

  Therefore, in the present invention, the depth of the initial crack is 1.14 times or more and 1.67 times or less the thickness of the tempered glass tempering layer. For this reason, a desired scribe groove can be formed stably.

The scribing method of the glass substrate according to the third invention is the scribing method of the second invention,
In the first step, the initial crack is not deeper than 5.4% of the total thickness of the tempered glass.

  As described above, even if the depth of the initial crack is 1.14 to 1.67 times that of the reinforcing layer, if the total thickness of the glass substrate is thin, if the initial crack is deeply formed, the crack progresses along the scribe line. May not.

  Therefore, in the present invention, the depth of the initial crack is made not to exceed 5.4% of the total thickness of the tempered glass. For this reason, a desired scribe groove can be formed stably.

As described above, in the present invention, a desired scribe groove can be formed relatively easily and stably with respect to the tempered glass whose surface is strengthened.

The schematic block diagram of the apparatus for enforcing the scribe method by one Embodiment of this invention. The figure which shows the relationship between the pressing load and initial crack for the initial crack formation with respect to 0.55 mm of thickness tempered glass, and the scribe result. The expanded sectional view of a part of tempered glass in which the initial crack was formed. The figure which shows the relationship between the pressing load for initial crack formation with respect to the tempered glass whose thickness is 0.7 mm, and an initial crack, and a scribe result. The figure which shows the relationship between the pressing load for initial crack formation with respect to the tempered glass whose thickness is 1.1 mm, and an initial crack, and a scribe result.

[Device configuration]
FIG. 1 is a diagram showing a schematic configuration of a scribing apparatus for carrying out a method according to an embodiment of the present invention. The scribe device 1 is a device for dividing a mother glass substrate into a plurality of glass substrates used for an FPD (flat panel display), for example. As the glass substrate here, chemically strengthened glass having a tempered layer formed on the surface is mainly used. As described above, this chemically strengthened glass has a tempered layer having a compressive stress on the surface by an ion exchange treatment.

The scribing apparatus 1 includes an irradiation unit 2 that irradiates a laser beam toward the glass substrate G, a cooling unit 3, and a moving unit (not shown). The cooling unit 3 forms a cooling spot CP by injecting a refrigerant supplied from a refrigerant source (not shown) through the nozzle 4. The moving unit is the irradiation unit 2
The nozzle 4 of the cooling unit 3 is moved relative to the glass substrate G along the scribe line SL set on the glass substrate G.

The irradiation unit 1 includes a laser oscillator (for example, a CO ₂ laser) that irradiates a laser beam LB,
This laser beam LB is irradiated as a beam spot LS onto the glass substrate G through the optical system.

Although not shown here, an initial crack forming means for forming an initial crack serving as a starting point for scribing is provided at the end of the glass substrate G. As an initial crack formation means,
A mechanical tool such as an indenter or a cutter wheel is used, but an initial crack can be formed by laser ablation.

[Scribe method]
First, as shown in FIG. 1, an initial crack TR serving as a starting point for scribing is formed at the end of the glass substrate G using an initial crack forming means such as a cutter wheel. At this time, the depth of the initial crack is set to such a depth that the reinforced layer having compressive stress formed on the surface of the tempered glass is removed. Specifically, the depth of the initial crack is 1.14 times to 1.67 times the thickness of the reinforcing layer.

Next, the laser beam LB is irradiated from the irradiation unit 1 to the glass substrate G. This laser beam LB is irradiated onto the glass substrate G as a beam spot LS. Then, the laser beam LB emitted from the irradiation unit 1 is moved relative to the glass substrate G along the scribe line SL. The glass substrate G is heated to a temperature lower than the softening point of the glass substrate G by the beam spot LS. Further, the cooling spot CP is made to follow behind the moving direction of the beam spot LS.

As described above, compressive stress is generated in the vicinity of the beam spot LS heated by the irradiation of the laser beam LB, but immediately after that, the cooling spot CP is formed by the injection of the refrigerant, which is effective for forming vertical cracks. Tensile stress is generated. Due to this tensile stress, the glass substrate G
A vertical crack is formed along the scribe line SL starting from the initial crack TR formed at the end of the slab, and a desired scribe groove is formed.

[Experiment 1]
FIG. 2 shows Experimental Example 1 in which a scribe groove is formed in a tempered glass having an overall thickness of 0.55 mm and a reinforced layer thickness of 18 μm. Specifically, FIG. 2 shows the relationship between the pressing load on the glass of the tool (indenter) at the time of initial crack formation and the groove depth at that time, and the scribing result by the subsequent laser heating and cooling treatment. .

In this case, the laser output for the heat treatment is 200 W, and the processing speed is 230 mm / sec. Also,
The cooling condition is that a cooling nozzle is disposed at a height of 4 mm at the rear end of the beam, and cooling water and air are discharged to a portion heated by the beam spot.

From Experimental Example 1, it can be seen that when the groove depth of the initial crack is 19 to 30 μm (1.05 to 1.67 times the thickness of the reinforcing layer), a desired scribe groove is formed along the planned scribe line.
It can be seen that if the groove depth is less than 19 μm, the crack does not progress reliably (unstable), and if it exceeds 30 μm, a crack occurs and a crack is formed in addition to the scribe line.

An example of the groove depth of the initial crack is shown in FIG. As shown in FIG. 3, the depth to the deepest part where a predetermined area is secured is defined as “groove depth”, and cracks that partially reach the deep part are ignored. .

[Experiment 2]
FIG. 4 shows an experimental example 2 in which scribe grooves are formed in a tempered glass having an overall thickness of 0.7 mm and a reinforced layer thickness of 21 μm. The relationship between the horizontal axis and the vertical axis in the figure is the same as in FIG. In this case, the laser output for the heat treatment is 200 W, and the processing speed is 170 mm / sec. The cooling conditions are the same as in Experimental Example 1.

From Experimental Example 2, the depth of the initial crack is about 24 to 50 μm (1.14 to 2.38 times the thickness of the reinforcing layer).
Then, it can be seen that a desired scribe groove is formed along the scribe line. It can be seen that when the groove depth is less than 24 μm, the crack does not progress reliably (unstable), and when the groove depth exceeds 50 μm, the crack occurs and a crack is formed other than the planned scribe line. If the pressing load is about 6 to 24 N, a desired scribe groove is formed even if the groove depth exceeds 50 μm. However, when attention is paid only to the groove depth, the groove depth of the initial crack is about 24 to 50 μm is reasonable.

[Experiment 3]
FIG. 5 shows Experimental Example 3 in which a scribe groove was formed in a tempered glass having an overall thickness of 1.1 mm and a reinforced layer thickness of 34 μm. The relationship between the horizontal axis and the vertical axis in the figure is the same as in FIG. In this case, the laser output for the heat treatment is 200 W, and the processing speed is 170 mm / sec. The cooling conditions are the same as in Experimental Example 1.

From Experimental Example 3, the initial crack depth was about 24-60 μm (0.71-1.76 times the thickness of the reinforcing layer).
Then, it can be seen that a desired scribe groove is formed along the scribe line. When the groove depth is too shallow, the crack does not progress, and when it exceeds 60 μm, the crack progress is unstable. As in Experimental Example 2, if the pressing load is about 6N to 24N, a desired scribe groove is formed even if the groove depth exceeds 60 μm. The appropriate groove depth is about 24-60μm. [Summary]
From the above, it can be seen that the depth of the initial crack is desirably 1.14 times or more and 1.67 times or less the thickness of the tempered glass reinforced layer in order to form a desired scribe groove along the scribe line. The depth of the initial crack is 30 μm (5.5%) or less when the glass plate thickness is 0.55 mm, 50 μm (7.1%) or less when the glass plate thickness is 0.7 mm, and the glass plate thickness is 1.1 mm.
Then, it is understood that it is desirable to be 60 μm (5.4%) or less. This indicates that the depth of the initial crack is desirably 5.4% or less of the glass thickness.

[Feature]
(1) When forming the initial crack, the groove depth is set to a depth that exceeds the reinforcing layer on the surface having compressive stress. Specifically, since the depth of the initial crack is 1.14 times or more and 1.67 times or less the thickness of the tempered glass strengthening layer, a desired scribe groove can be formed stably.

  (2) Since the depth of the initial crack is 5.4% or less of the total thickness of the tempered glass, it is possible to prevent the crack from progressing in an unintended direction.

[Other Embodiments]
The present invention is not limited to the above-described embodiments, and various changes or modifications can be made without departing from the scope of the present invention.

In the embodiment, the case where the scribe groove is formed in the second step (laser irradiation and cooling treatment) has been described. However, the present invention is similarly applied to the case where the glass is divided in the second step. Can do.

1 Scribe device
G Glass substrate
LB laser beam
LS beam spot
SL scribe line
CP cooling spot

Claims (3)

A scribing method of a glass substrate for scribing a tempered glass having a tempered layer having a compressive stress on its surface,
A first step of forming an initial crack on the surface of the tempered glass at a depth exceeding the tempered layer;
A second step of irradiating and heating the initial crack with laser light, cooling the heated region, and developing the crack along a scribe line;
A method for scribing a glass substrate. 2. The glass substrate scribing method according to claim 1, wherein in the first step, the depth of the initial crack is 1.14 to 1.67 times the thickness of the tempered glass tempering layer.   The scribing method for a glass substrate according to claim 2, wherein in the first step, the initial crack has a depth not exceeding 5.4% of the total thickness of the tempered glass.

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