JP2013227175A - Method of dividing glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of dividing reinforced glass easily, safely and reducing deterioration of its strength.SOLUTION: There is provided a method of dividing reinforced glass having a compression stress on the surface and a tensile stress inside. In a first process, a laser is focused at a first depth location inside a substrate, and the laser is scanned along a predetermined dividing line to form machining marks inside the substrate along the predetermined dividing line, and in a second process, a location of starting point of a crack for division is set on the predetermined dividing line, and the laser is focused at a second depth location between the first depth location and the surface of the substrate in a part of a region including the location of the starting point of the crack on the predetermined dividing line, and the laser strong enough to develop cracks on the machining marks and on the surface of the substrate is irradiated to form cracks, and the resultant cracks are developed along the predetermined dividing line to divide the substrate.

Description

  The present invention relates to a method for dividing a glass substrate, and more particularly to a method for dividing a glass substrate for dividing a tempered glass having a compressive stress on its surface and a tensile stress inside.

As a technique for dividing a glass substrate with a laser, there is a method in which a glass substrate is irradiated with a CO ₂ laser to cause thermal stress to divide the glass substrate. Even when the tempered glass whose surface is strengthened is divided, it is possible to divide by using such a conventional technique.

  However, if the degree of strengthening of the surface of the glass substrate is increased, the conventional technology as described above cannot be divided. Therefore, as a method for dividing high-strength glass, a method for dividing as shown in Patent Document 1 is provided.

  In the method disclosed in Patent Document 1, first, a first damage line as a modified layer is formed in an internal region where a reinforcing layer is not formed on a glass substrate. Similarly, the second damage line is formed in a region shallower than the first damage line in the inner region where the reinforcing layer is not formed. By forming these damage lines, cracks develop along the planned dividing line, and the glass substrate is divided. In addition, it is described that a mechanical force is applied by pressing both sides of the damage line by mechanical scribe forming a groove by a cutter or by manual or mechanical operation at the time of the division.

WO2010 / 096359A1 (paragraphs 0024, 0026, 0027, 0031, 0032, etc.)

  In the cutting method described in Patent Document 1, the damage line is formed in a relatively shallow region from the substrate surface. For this reason, it may be naturally divided at the time when the damage line is formed, while a dividing step as a subsequent step may be required after the formation of the damage line. That is, in the method disclosed in Patent Document 1, it is impossible to predict whether the cut will be full cut or half cut at the time when the damage line is formed, and the division processing becomes unstable.

  Further, when the dividing step is necessary after the damage line is formed, as described above, mechanical scribe, treatment for applying a bending force to both sides of the damage line, and the like are necessary. In this case, there is a problem that damage such as chipping occurs on the substrate surface, leading to a decrease in strength.

  An object of the present invention is to make it possible to divide the tempered glass easily and stably while suppressing a decrease in strength.

  The method for dividing a glass substrate according to the first invention is a method for dividing a tempered glass having a compressive stress on its surface and a tensile stress inside, and includes a first step and a second step. In the first step, a laser beam is condensed at a first depth position inside the substrate, and the laser is scanned along the planned division line, thereby forming a processing mark in the substrate along the planned division line. In the second step, a position to be a starting point of a crack for splitting is set on the planned cutting line, and a first depth position between a first depth position and a substrate surface in a partial region on the planned cutting line including the crack starting point position is set. Condensing the laser at two depth positions and irradiating the laser with the intensity that can develop cracks on the processing traces and the substrate surface to form cracks, and propagating the formed cracks along the planned cutting line Divide the board.

  Here, first, a processing mark is formed along the planned dividing line inside the substrate. Next, a crack starting position is set at a certain position on the planned dividing line, and the laser is focused between a processing mark and a substrate surface in a partial region including the crack starting position and irradiated with the laser. By this laser irradiation, cracks develop on the processing marks and the substrate surface, and further cracks develop along the line to be divided. Thereby, a board | substrate is parted.

  Here, it is possible to prevent the substrate from being unintentionally divided at the end of the first step by executing the second step. That is, a stable division process can be executed. Further, since mechanical scribing or the like is not required at the time of division, processing is simplified, and damage to the substrate surface can be suppressed, so that a decrease in strength of the substrate can be suppressed.

  The glass substrate dividing method according to the second invention is the glass substrate dividing method according to the first invention, wherein the first depth position in the first step is 365 μm or more and 685 μm or less from the surface of the substrate.

  When the depth of the processing mark formed in the first step is shallow from the substrate surface, the substrate may be naturally divided at the end of the first step, and the dividing process becomes unstable. Conversely, if the depth of the processing marks formed in the first step is too deep from the substrate surface, the substrate is not stably and stably divided even if the second step is executed.

  Therefore, in the first step, it is necessary to focus the laser to a depth of 365 μm or more and 685 μm or less to form a processing mark. Thereby, it is possible to prevent the substrate from being unintentionally divided at the end of the first step, and it is possible to favorably divide the substrate in the second step.

  The glass substrate dividing method according to the third aspect of the invention is the dividing method of the second invention, wherein the second depth position in the second step is within the range of 140 μm or more and 365 μm or less from the substrate surface.

  Here, by setting the laser condensing position in the second step in the above range, a crack can be formed between the processing trace formed in the first step and the substrate surface, and the crack is scheduled to be divided. You can make progress.

  The glass substrate dividing method according to a fourth invention is the dividing method according to the second invention, wherein the first depth position in the first step is 185 μm or less on the front surface side and 135 μm or less on the back surface side from the center position in the thickness direction of the substrate. Is within the range.

  In the first step, if a processing mark is formed in a region biased to the front surface or the back surface of the substrate, the substrate may be divided at the end of the first step or in the middle of the first step, and stable division cannot be performed. .

  Therefore, in the fourth invention, the first depth position in the first step is the central portion in the thickness direction of the substrate, and a processing mark is formed in the region. For this reason, the stable parting process can be performed.

  The glass substrate dividing method according to a fifth aspect of the invention is the dividing method of the second invention, wherein the first depth position in the first step is within a range of 415 μm or more and 735 μm or less from the back surface of the substrate.

  Here, in the first step, if a laser beam is focused on a region away from the back surface of the substrate to form a processing mark, a crack that has progressed toward the back surface is bent after the second step is performed, so that the separation on the back surface is interrupted. The line deviates from the line to be divided.

  Therefore, in the fifth invention, the first depth position in the first step is set within a predetermined range from the back surface of the substrate, and a processing mark is formed in the region. As a result, high-accuracy division can be performed.

  The glass substrate dividing method according to a sixth aspect of the present invention is the dividing method according to any one of the first to fifth aspects of the invention, wherein in the second step, the partial region irradiated with the laser is a portion within 10 mm from the substrate edge on the scanning start side. is there.

  Here, when the glass substrate is divided, generally, the substrate end is often discarded without being used as a final product. Therefore, by setting the portion that is easily damaged by the second laser irradiation as the substrate end on the scanning start side, a final product with good quality can be obtained.

  The glass substrate dividing method according to a seventh aspect of the present invention is the dividing method of the sixth aspect, wherein in the second step, the substrate surface is covered with a shielding object except for a partial region irradiated with the laser.

  The glass substrate dividing method according to an eighth aspect of the present invention is the dividing method of the sixth aspect, wherein in the second step, the irradiation of the laser to the substrate is stopped except for a partial region irradiated with the laser.

  The glass substrate dividing method according to the ninth invention is the dividing method of the first to eighth inventions, wherein in the first step, the laser output is 4 W or more and 8 W or less, and the scanning speed is 200 mm / s or more and 500 mm / s or less. is there.

  A glass substrate dividing method according to a tenth invention is the dividing method according to the ninth invention, wherein, in the second step, the laser output is 6 W or more and 8 W or less, and the scanning speed is 300 mm / s or more and 500 mm / s or less.

  As described above, in the present invention, the tempered glass having a tempered layer having a compressive stress on the surface can be easily and stably divided without reducing the strength of the glass substrate. .

The typical sectional view of tempered glass to which the parting method by one embodiment of the present invention is applied. The figure which shows the experimental result for investigating the process conditions (laser output and scanning speed) of the 1st process of the cutting method which concerns on this invention. The figure which shows the experimental result for investigating the process conditions of the 2nd process of the cutting method which concerns on this invention. The microscope picture which shows the mode of the dividing surface of the board | substrate by two times of laser irradiation. The microscope picture which shows the surface and divided surface of the board | substrate cut | disconnected by the cutting method by one Embodiment of this invention. The figure which shows the experimental result which investigated the conditions which can change the process position of the laser in a 1st process and a 2nd process, and can board | substrate parting.

[Glass substrate]
FIG. 1 shows an example of a cross-sectional configuration of a glass substrate as a part to be divided. This glass substrate is a tempered glass having a compressive stress on the surface and a tensile stress inside. Specifically, in the vicinity of the front and back surfaces, the closer to the front and back surfaces, the greater the compressive stress (CS). And inside the board | substrate which reaches predetermined depth from the surface and the back surface, it has a tensile stress (CT) conversely. In FIG. 1, “DOL” indicates the depth of the reinforcing layer having compressive stress on the substrate surface.

[Division method]
When dividing the tempered glass as described above (hereinafter sometimes simply referred to as “substrate”), the following two steps are executed.

<First step>
The laser is focused on a region having a tensile stress inside the substrate, and the laser is scanned along a line to be cut. As a result, a processing mark is formed inside the substrate along the division line. The processing mark is an area where the substrate is once softened or melted by the laser and solidified again.

<Second step>
After completion of the first step, the laser is focused between the processing trace formed in the first step and the substrate surface, and the line is scheduled to be divided over a predetermined range from the substrate end surface (laser scanning start end on the substrate surface). A laser is scanned along. At this time, the intensity of the laser is set such that a crack can propagate on the processing trace and the substrate surface, and the formed crack can propagate along the entire line to be cut.

Experimental example

  The experimental results for setting the conditions for each process are shown below. In each experiment, the object to be divided is high-tempered glass having a thickness of 1.1 mm (see FIG. 1 for the cross-sectional configuration). Laser irradiation was performed from the surface side of the substrate. Here, the surface of the substrate irradiated with laser is referred to as “front surface”, and the surface opposite to “front surface” is referred to as “back surface”.

[Experiment 1: Setting conditions for the first step]
FIG. 2 shows the experimental results for setting the laser irradiation conditions in the first step. The table shown in FIG. 2 shows the processing results of one laser irradiation, and the meaning of each symbol in the table is as follows.

“○”: Can be divided by two laser irradiations “△”: Divided by one laser irradiation “△ ×”: Divided off from the planned dividing line “XX”: Cannot be divided by two laser irradiations ( There is a processing mark by one laser irradiation)
"-": Cannot be divided by two laser irradiations (no processing marks after one laser irradiation)
The laser irradiation conditions are as follows.

・ Repetition frequency: 3MHz
・ Laser output: 2.0-8.0W
・ Scanning speed: 50-500mm / s
・ Processing position (condensing position): 535 μm from the surface of the substrate
From the results of Experiment 1 above, it can be seen that as the processing conditions in the first step, it is preferable to set the laser output to 4 W and set the scanning speed in the range of 200 to 300 mm / s.

[Experiment 2: Condition setting for the second step]
FIG. 3 shows the results of an experiment in which the laser irradiation conditions in the first step are set as follows, and the laser irradiation conditions (scanning speed and processing position) in the second step are variously changed to investigate the conditions that can be divided. Yes. In Experiment 2, in the second step, the laser was scanned over the entire parting line rather than partly.

<First step>
・ Repetition frequency: 3MHz
・ Laser output: 4.0W
・ Scanning speed: 300mm / s
・ Processing position (focal position): 535 μm from the surface of the substrate
The meaning of each symbol in the table of FIG. 3 is as follows.

"○": Can be divided (After laser irradiation, along the line)
“△”: Can be divided (several minutes after laser irradiation)
"□": Can be divided (parting off the line)
“×”: Processing mark (cannot be divided)
From the results of Experiment 2, when the laser irradiation conditions in the first step are set as described above and the processing position is set to 535 μm, the second step can be reliably divided by processing under the following conditions. I know that there is.

<Second step>
・ Repetition frequency: 3MHz
・ Laser output: 8.0W
・ Scanning speed: 500mm / s
Processing position (focal position): 140 to 365 μm from the surface of the substrate
[Experiment 3]
FIG. 4 shows a result of an experiment in which a laser is irradiated to only a part of a division planned line in the substrate dividing step (second step). FIG. 4A shows a state of a divided cross section when the laser is irradiated along a planned dividing line at a position 20 mm away from the laser scanning start end in the first step. FIG. 4B shows a state of a divided cross section when the laser is irradiated along the planned dividing line at a position 20 mm away from the end of the laser scanning in the first step. FIG. 4C shows a state of a divided cross section when the laser is scanned along the planned dividing line within a range of 20 mm from the laser scanning start end of the first step. The processing conditions are the same as the conditions obtained in Experiment 2. Even if the laser irradiation position in the second step is changed to the center portion of the substrate or the laser scanning end portion in the first step, the division is possible.

  From the result of this experiment 3, in the second step, it is possible to divide the substrate by cracking along the processing marks formed in the first step by irradiating only a part of the planned cutting line with laser. I understand.

  Although not shown here, the laser irradiation region in the second step could be divided even by irradiating the laser within a range of 1 mm along the planned division line.

[Experiment 4: Example]
The state of the sectional surface of the substrate processed in Experiment 3 was confirmed. The result is shown in FIG. FIG. 5A is a micrograph (left in the figure) of the substrate surface of the portion irradiated with the laser in the second step, and a micrograph of the corresponding cross section (right in the figure). FIG. 5B is a micrograph of the substrate surface at the center of the substrate (the portion not irradiated with the laser in the second step) (left of the figure) and a micrograph of the corresponding cross section (right of the figure). . The processing conditions in each step here are as follows.

First step:
・ Repetition frequency: 3MHz
・ Laser output: 4.0W
・ Scanning speed: 300mm / s
・ Processing position (focal position): 535 μm from the surface of the substrate
Second step:
・ Repetition frequency: 3MHz
・ Laser output: 8.0W
・ Scanning speed: 500mm / s
Processing position (focal position): 213 μm from the surface of the substrate
・ Laser irradiation part: scanning start edge (cut-in part) in the range of 10mm (other than shielding)
From the result of Experiment 4, the portion irradiated with the laser in the second step has a chip of about 200 μm in size on the substrate surface, but the portion not irradiated with the laser in the second step has chipped on the substrate surface. It turns out that does not occur. The straight advanceability of the cracks on the surface of the substrate in the portion not irradiated with the laser in the second step (deviation from the line to be divided) was better than the portion irradiated with the laser in the second step.

  From the above, it can be seen that the region to be irradiated with the laser in the second step is preferably a region (for example, the edge of the substrate) that is discarded when the final product is obtained.

[Experiment 5: Specification of machining position]
FIG. 6 shows an experimental result in which the laser processing position in the first step was changed in the range of 365 to 998 μm, and the laser processing position in the second step was changed to investigate the conditions for dividing the substrate. Each processing condition here is as follows.

First step:
・ Repetition frequency: 3MHz
・ Laser output: 4.0W
・ Scanning speed: 300mm / s
Processing position (condensing position): 365 to 998 μm from the surface of the substrate
Second step:
・ Repetition frequency: 3MHz
・ Laser output: 8.0W
・ Scanning speed: 500mm / s
Processing position (condensing position): 140 to 998 μm from the surface of the substrate
The meaning of each symbol in the table of FIG. 6 is as follows.

"○": Can be divided (After laser irradiation, along the line)
"□": Dividing from the line "X": Processing trace (cannot be divided)
From this experimental result, when the processing position in the first step is set to 365 to 857 μm, it is necessary to move the processing position in the second step to the surface side by 225 to 472 μm from the processing position in the first step. Recognize.

  The processing position in the first step is preferably 185 μm or less on the front surface side and 307 μm or less on the back surface side from the central thickness position (550 μm from the front surface) of the substrate. This is because if a processing mark is formed in a region biased to the front surface or the back surface of the substrate, the substrate may be divided at the end of the first step or in the middle of the first step, and stable division cannot be performed.

  Moreover, it is preferable that the processing position in a 1st process exists in the range of 415-735 micrometers from the back surface of a board | substrate. In the first step, if the laser is focused on a region away from the back surface of the substrate to form a processing mark, the crack that has progressed toward the back surface is bent after the second step is performed, and the dividing line on the back surface is broken. This is because it deviates from the planned line.

[Summary of experimental example]
<Processing method>
In the first step, a processing position (laser condensing position) is set in a portion where tensile stress is present inside the substrate, and the laser is irradiated over the entire parting line. Thereby, a processing mark is formed inside the substrate.

  In the second step, the laser is irradiated only to a partial region of the planned dividing line, the crack reaching the processing trace and the substrate surface is developed, and the crack is propagated along the planned dividing line. As a result, the substrate is naturally divided along the division line. Note that chipping or the like may occur on the substrate surface due to the second laser irradiation, leading to a decrease in strength. Therefore, it is desirable that the region to be irradiated with the laser in the second step is a portion (for example, an end portion of the substrate) that is discarded in the final product state.

<Laser irradiation conditions>
Regarding the laser irradiation conditions, in each step, if the following conditions are satisfied, it can be divided by the method of the present invention.

First step:
・ Repetition frequency: 3MHz
Laser output: 4.0 W (preferably 4 W or more and 8 W or less)
Scanning speed: 200 to 300 mm / s (preferably 200 mm / s or more and 500 mm / s or less)
Second step:
・ Repetition frequency: 3MHz
Laser output: 8.0 W (preferably 6 W or more and 8 W or less)
Scanning speed: 500 mm / s (preferably 300 mm / s to 500 mm / s)
<Processing position>
With respect to the processing position, each process can be divided by the method of the present invention under the following conditions.

  1st process: The range of 365-685 micrometers from a substrate surface.

            A range of 185 or more on the front side and 135 μm or less on the back side from the center position of the substrate.

            The range from 415 to 735 μm from the back surface of the substrate.

  Second step: A position in the range of 140 to 365 [mu] m from the substrate surface and a position on the substrate surface side of 225 to 472 [mu] m from the processing position in the first step (which is also a position where processing marks are formed).

[Feature]
(1) In the second step, the substrate can be divided by irradiating a partial region of the substrate with laser. Therefore, it is possible to prevent the substrate from being naturally divided unintentionally, and a stable division process can be executed.

  (2) Since the laser irradiation in the second step is only part of the substrate, damage to the substrate surface can be minimized, degradation of the cutting quality can be suppressed, and a reduction in the strength of the substrate can be prevented. In particular, the quality degradation of the product can be eliminated by performing the second laser irradiation on the discarded part in the final product.

  (3) Since mechanical scribing or the like is not required at the time of dividing, the processing is simplified, and a decrease in the strength of the substrate can be suppressed as described above.

  (4) By appropriately setting the processing positions in the first step and the second step, stable division processing can be performed.

[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.

  As a method for shielding the laser irradiation in the second step, a laser reflecting material such as aluminum may be disposed on the substrate surface, or the laser irradiation may be performed in a region other than the laser irradiation region.

  Moreover, in the said embodiment, although the partial area | region (area | region used as the origin of a crack) irradiated with a laser in a 2nd process was made into the edge part area | region of a board | substrate, as long as it is on the division | segmentation planned line, it will be in any position. Good. For example, the center position of the substrate or the intersection position at the time of cross scribing may be set as the crack starting position.

Claims (10)

A method for dividing a glass substrate for dividing a tempered glass having a compressive stress on the surface and a tensile stress inside,
A first step of forming a processing mark inside the substrate along the planned dividing line by condensing the laser at a first depth position inside the substrate and scanning the laser along the planned dividing line;
A position to be a starting point of a crack for splitting is set on the planned cutting line, and a second depth between the first depth position and the substrate surface in a partial region on the planned cutting line including the crack starting point position. The laser beam is focused at a certain position, and the crack is formed by irradiating the processing trace and the laser beam with a strength capable of propagating a crack on the substrate surface, and the formed crack is allowed to propagate along the division line. A second step of dividing the substrate,
Glass substrate cutting method.   The glass substrate cutting method according to claim 1, wherein the first depth position in the first step is 365 μm or more and 685 μm or less from the surface of the substrate.   The second depth position in the second step is condensed within a range of 140 μm or more and 365 μm or less from the substrate surface and within a range of 225 μm or more and 472 μm or less from the processing mark formed in the first step. 2. The method for dividing a glass substrate according to 2.   3. The glass substrate cutting method according to claim 2, wherein the first depth position in the first step is within a range of 185 μm or less on the front surface side and 135 μm or less on the back surface side from the center position in the thickness direction of the substrate.   The glass substrate cutting method according to claim 2, wherein the first depth position in the first step is in a range of 415 μm to 735 μm from the back surface of the substrate.   6. The glass substrate cutting method according to claim 1, wherein in the second step, the partial region irradiated with the laser is a portion within 10 mm from the substrate edge on the scanning start side.   The method for dividing a glass substrate according to claim 6, wherein in the second step, the substrate surface is covered with a shielding object except for the partial region irradiated with the laser.   The glass substrate cutting method according to claim 6, wherein, in the second step, irradiation of the laser to the substrate is stopped except for the partial region irradiated with the laser.   The glass substrate cutting method according to any one of claims 1 to 8, wherein, in the first step, the laser output is 4 W or more and 8 W or less, and the scanning speed is 200 mm / s or more and 500 mm / s or less.   The glass substrate cutting method according to claim 9, wherein in the second step, the laser output is 6 W or more and 8 W or less, and the scanning speed is 300 mm / s or more and 500 mm / s or less.