JP6049848B2 - Glass substrate cutting method - Google Patents

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 glass substrate dividing method according to the first invention is a method for dividing a tempered glass having a compressive stress on the surface and a tensile stress inside, and includes a processing mark forming step, an intermediate step, and a dividing step. ,including. In the processing trace forming step, the processing mark is formed inside the substrate by condensing the laser at the first depth position in the region having the tensile stress inside the substrate and scanning the laser along the planned dividing line. In the intermediate process, the laser is condensed at a second depth position on one surface side of the front surface or the back surface of the substrate from the first depth position, and the laser is scanned only in a partial region along the planned dividing line. Form cracks inside. In the dividing step, after the intermediate step, the laser is condensed at a depth position on one surface side of the substrate from the immediately preceding laser condensing position, and the laser is scanned only on at least a part of the partial region, and one side of the substrate is scanned. A crack reaching the surface of the substrate is formed, and the formed crack is developed along a line to be divided to divide the substrate.

  Here, first, a processing mark is formed at the first depth position inside the substrate along the planned division line inside the substrate. Next, the laser condensing position is set at the second depth position on the one surface side of the front surface or the back surface of the substrate from the first depth position, and the laser is irradiated only to a partial region on the planned dividing line. . Thereby, a crack is formed inside the substrate. Further, the laser is condensed at a depth position on one surface side of the substrate from the previous laser condensing position, and the laser is irradiated only to at least a part of the partial region. As a result, a crack that reaches one surface of the substrate is formed, and the formed crack propagates along the planned dividing line, thereby dividing the substrate.

  Here, it is possible to prevent the substrate from being unintentionally divided at the end of the previous step by performing the dividing 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. Further, in this method, the laser irradiation is performed three times or more, and the substrate can be reliably divided particularly when the substrate is thick.

  The glass substrate dividing method according to a second aspect of the invention is the dividing method of the first invention, wherein in the dividing step, the laser is condensed at a third depth position on one surface side of the substrate from the second depth position.

  Here, similarly to the first invention, even a thick substrate can be divided stably and reliably. In addition, since damage to the substrate surface can be suppressed, a decrease in strength of the substrate can be suppressed.

  The glass substrate dividing method according to the third aspect of the present invention is the dividing method of the first or second aspect, wherein the thickness of the substrate is 1.1 mm or more.

  The glass substrate cutting method according to a fourth aspect of the present invention is the glass substrate cutting method according to any one of the first to third aspects of the invention, wherein the first depth position in the processing mark forming step is the laser irradiation surface side from the center position in the thickness direction of the substrate. Is 185 μm or less on the opposite side and 135 μm or less on the opposite side.

  In the process trace formation process, if a process trace is formed in a region biased to the front or back surface of the substrate, the substrate may be divided at the end of the process trace formation process or in the middle of this process. Can not.

  Therefore, in the fourth invention, the first depth position in the processing mark forming step is the central portion in the thickness direction of the substrate, and the processing marks are 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 present invention is the glass substrate dividing method according to any one of the first to fourth aspects, wherein the distance between adjacent depth positions is not less than 225 μm and not more than 472 μm.

  By setting the interval between the adjacent depth positions to the above interval, the crack reaches the processing trace and one surface of the substrate, and the substrate can be stably divided.

  A glass substrate dividing method according to a sixth invention is the method according to any one of the first to fifth inventions, wherein the laser condensing position closest to the laser irradiation surface side of the substrate in the dividing step is 140 μm or more from the laser irradiation surface of the substrate. It is within the range of 365 μm or less.

  Here, by setting the final laser focusing position in the above-mentioned range in the dividing step, a crack can be formed between the processing mark formed in the previous step and the substrate surface, and the crack is scheduled to be divided. You can make progress along the line.

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

  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 laser irradiation after the intermediate step 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 an eighth aspect of the present invention is the dividing method according to any one of the first to seventh inventions, wherein in the intermediate step and the dividing step, the irradiation of the laser to the substrate is stopped except in the laser irradiation region. .

  The glass substrate dividing method according to a ninth aspect of the present invention is the method according to any one of the first to eighth aspects, wherein the laser irradiation region in the dividing step is narrower than a partial region in the intermediate step.

  Here, the time required for the dividing step can be shortened.

  According to a tenth aspect of the present invention, there is provided the glass substrate dividing method according to any one of the first to ninth aspects, wherein the laser output is 4 W or more and 8 W or less and the scanning speed is 150 mm / s or more. 500 mm / s or less.

  The glass substrate dividing method according to the eleventh aspect of the invention is the dividing method of the tenth invention, wherein the laser output is 6 W or more and 8 W or less in the intermediate step and the dividing step, and the scanning speed is 300 mm / s or more and 800 mm / s or less. It is.

  As described above, according to the present invention, the tempered glass having a tempered layer having a compressive stress on the surface thereof is easily and stably reduced in strength, particularly when the substrate is thick. Splitting can be performed without causing them to occur.

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 cross section of the board | substrate divided | segmented by laser irradiation twice. 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. The typical explanatory view of the cutting method by one embodiment of the present invention.

[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 the tempered glass as described above (hereinafter sometimes simply referred to as “substrate”) is divided, the following steps are executed.

<First step: process mark formation step>
A laser is condensed at a first depth position in a region having a tensile stress inside the substrate, and the laser is irradiated from the surface of the substrate to scan along a line to be cut. As a result, a processing mark is formed inside the substrate along the division line. Here, the processing mark is a region where the substrate is once softened or melted by the laser and solidified again.

<Second step: Intermediate step>
After completion of the first step, the laser is focused at a second depth position on the substrate surface side shallower than the first depth position, and is scheduled to be divided only within a predetermined range from the substrate end surface (laser scanning start end on the substrate surface). Scan the laser along the line. At this time, the second depth position and the laser intensity are set so that a crack can be propagated to a previously formed processing mark by laser irradiation.

<Third step: Cutting step>
After the end of the second step, the laser is focused on the third depth position on the substrate surface side shallower than the second depth position, and the line is scheduled to be divided in the range irradiated with the laser in the second step or in a shorter range. A laser is scanned along. The third depth position and the laser intensity at this time are set so that the crack reaches the substrate surface by laser irradiation and the crack can be propagated as a whole along the line to be divided.

Experimental example

  The experimental results for setting the conditions for each process are shown below. In each experiment, the object to be divided is all high-tempered glass (see FIG. 1 for the cross-sectional configuration).

[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. Here, the thickness of the substrate is 1.1 mm.

“○”: 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 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. The thickness of the substrate is 1.1 mm.

<First step>
・ Repetition frequency: 3MHz
・ Laser output: 4.0W
・ Scanning speed: 300mm / s
-Processing position (focal position): 535 μm (substrate surface is 0 μm)
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 (substrate surface is 0 μm)

[Experiment 3: Irradiation position in the second step]
FIG. 4 shows a result of an experiment in which a laser is irradiated only to a part of the planned dividing line in the second step of the substrate. 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 Experiment 3, in the second step, it is possible to divide the substrate by irradiating only a part of the planned cutting line with a laser so that a crack develops along the processing mark formed in the first step. I understand that.

  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: Damage to substrate surface]
Experiment 4 was conducted based on the results of Experiments 1 to 3 above. The result is shown in FIG. FIG. 5A is a micrograph (left of the figure) of the substrate surface of the cut-in part (the part irradiated with the laser twice) and a micrograph of the corresponding cross section (right of the figure). FIG. 5B shows a micrograph (left in the figure) of the substrate surface at the center of the substrate (the part irradiated with the laser only once) and a micrograph of the corresponding cross section (right in 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 (substrate surface is 0 μm)
Second step:
・ Repetition frequency: 3MHz
・ Laser output: 8.0W
・ Scanning speed: 500mm / s
Processing position (focal position): 213 μm (substrate surface is 0 μm)
・ 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 twice has a chip of about 200 μm in size on the substrate surface, but the shielded portion (laser is irradiated only once) has a chip on the substrate surface. It turns out that it has not occurred. In addition, the straight advanceability of the crack (deviation from the parting planned line) was within ± 50 μm (measurement sample: n = 3) in the shielding part.

  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]
The laser processing position in the first step can be changed in the range of 365 to 998 μm (substrate surface is 0 μm), and the laser processing position in the second step can be changed in the range of 140 to 998 μm (substrate surface is 0 μm) to divide the substrate. FIG. 6 shows the experimental results of investigating the conditions. Each processing condition here is as follows.

First step:
・ Repetition frequency: 3MHz
・ Laser output: 4.0W
・ Scanning speed: 300mm / s
Second step:
・ Repetition frequency: 3MHz
・ Laser output: 8.0W
・ Scanning speed: 500mm / s
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, it is understood that when the processing position in the first step is 365 to 685 μm, the second step is naturally divided if the processing position in the second step is 365 μm or less from the substrate surface. Further, it is understood that the processing position in the second step needs to be moved to the surface side by 225 (365-140) μm or more and 472 (685-213) μm or less from the processing position in the first step.

  The processing position in the first step is preferably 185 μm (365 μm) or more on the front surface side and 135 μm (685 μm) or less on the back surface side from the central position (550 μm) of the substrate thickness. 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 365-685 micrometers (a board | substrate surface is 0 micrometer) from the back surface of a board | substrate. 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, the crack that has progressed toward the back surface is bent after the execution of the second step, and the dividing line on the back surface is broken. This is because it deviates from the planned line.

[When the substrate is thick]
In all the above experiments, the thickness of the substrate is 1.1 mm. Therefore, from the above experimental results, when the thickness of the substrate is 1.1 mm or more, as shown in FIG. 7, the same process as the second process (third process: cutting process) is performed under the processing conditions of the second process. It turns out that it only needs to be executed repeatedly.

  Specifically, when the processing position is 140 μm or less from the substrate surface by repeatedly executing laser irradiation to a partial region while maintaining the distance from the processing position in the immediately preceding process within the range of 225 to 472 μm, The substrate is naturally divided by the laser irradiation.

<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: 4.0W (4W to 8W)
・ Scanning speed: 200-300mm / s (150mm / s or more and 500mm / s is acceptable)
Second step and third step:
・ Repetition frequency: 3MHz
・ Laser output: 8.0W (6W to 8W is acceptable)
・ Scanning speed: 500mm / s (300mm / s or more and 800mm / s or less is acceptable)
<Processing position>
With respect to the processing position, each process can be divided by the method of the present invention under the following conditions.

First step: A range of 365 to 685 μm from the substrate surface
Range from +185 to −135 μm from the center position of the substrate (0 μm).

            “+” Is the front surface side (laser irradiation surface side), and “−” is the back surface side.

  Second step: The substrate surface side is 225 to 472 μm from the processing position of the first step.

  Third step: 225 to 472 μm from the immediately preceding processing position, and the last processing position is in the range of 140 to 365 μm from the substrate surface.

[Feature]
(1) In the dividing 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 laser irradiation in the intermediate process and the cutting process 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 deterioration of the product can be eliminated by performing the second and subsequent laser irradiations on the discarded parts 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.

[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.

  The laser irradiation position in the intermediate process and the dividing process is set to the back surface side (surface opposite to the laser irradiation surface) from the first depth position, and a crack reaching the back surface of the substrate is formed in the dividing process. Also good.

  Moreover, in the said embodiment, although the partial area | region (area | region used as the origin of a crack) irradiated with a laser in the intermediate | middle process and the cutting process was made into the edge part area | region of a board | substrate, what kind of thing will be used if it is on a dividing line It may be a position. 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.

  In the dividing step, the laser irradiation region may be the same region as the intermediate step, or may be a region narrower than the laser irradiation region in the intermediate step.

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 processing mark forming step of forming a processing mark inside the substrate by condensing the laser at a first depth position in a region having a tensile stress inside the substrate and scanning the laser along a scheduled cutting line;
The laser is condensed at a second depth position on one side of the front surface or the back surface of the substrate from the first depth position, and the laser is scanned only in a partial region along the planned dividing line to enter the inside of the substrate. An intermediate process to form cracks;
After the intermediate step, the laser is focused on the third depth position on the one surface side of the substrate from the second depth position , and the laser is scanned only on at least a part of the partial region. A splitting step of splitting the substrate by forming a crack that reaches the one surface and advancing the formed crack along the planned split line;
Only including,
In the intermediate step, the second depth and the laser intensity are set so that a crack can be developed in a processing mark previously formed by laser irradiation,
In the dividing step, the third depth and the laser intensity are set by laser irradiation so that the crack reaches the one surface of the substrate and the crack can propagate to the entire dividing line. Yes,
Glass substrate cutting method. The method for dividing a glass substrate according to claim 1 , wherein the thickness of the substrate is 1.1 mm or more. Said first depth position in the working mark forming step, the following 185μm from the center position in the thickness direction of the substrate on the laser irradiation surface, is within the following 135μm on the opposite side, the glass according to claim 1 or 2 Substrate dividing method. The glass substrate cutting method according to any one of claims 1 to 3 , wherein an interval between adjacent depth positions is not less than 225 µm and not more than 472 µm. The glass substrate dividing method according to any one of claims 1 to 4 , wherein a laser condensing position closest to a laser irradiation surface of the substrate in the dividing step is within a range of 140 µm to 365 µm from the laser irradiation surface of the substrate. . Wherein in an intermediate step, a partial area to be laser irradiated is a portion within 10mm from the substrate edge of the scanning start side, cutting method of a glass substrate according to any one of claims 1 to 5. The glass substrate cutting method according to any one of claims 1 to 6 , wherein in the intermediate step and the dividing step, irradiation of the laser to the substrate is stopped except in a region irradiated with the laser. The method for dividing a glass substrate according to any one of claims 1 to 7 , wherein a laser irradiation region in the dividing step is a region narrower than a partial region in the intermediate step. In the processing marks forming step, the laser output is less than 4W or 8W, scanning speed is less than 150 mm / s or more 500 mm / s, cutting method of a glass substrate according to any one of claims 1 to 8. The method for dividing a glass substrate according to claim 9 , wherein in the intermediate step and the dividing 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 800 mm / s or less.