JP5352642B2 - 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 having a compressive stress on its surface.

  As a method of forming a scribe groove for dividing a glass substrate, there is a method of forming a scribe groove using a laser beam. In this case, laser light is irradiated along the scribe line, and a part of the substrate is melted and evaporated to form a scribe groove. 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 part causes a reduction in the strength of the substrate end face.

  Therefore, as another method of forming the scribe groove, there is a method as shown in Patent Document 1 or 2. 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.

  Further, in the method of forming a scribe groove by irradiating a laser beam, the scribe groove has a tendency to deepen at the peripheral edge of the glass substrate. If the glass substrate is divided along the scribe groove in this state, there arises a problem that the quality of the divided section is deteriorated and a problem that the scribe groove is not formed straight.

  Therefore, Patent Document 3 discloses a laser scribing method in which a region where no scribe groove is formed is formed at the end of a scribe line. According to this method, it is described that the quality of a section after division at the terminal portion of the glass substrate can be improved without complicated control.

Japanese Patent Laid-Open No. 3-489 JP-A-9-1370 Republished patent WO2007 / 094348

  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 (strengthening layer) whose surface is given compressive stress by ion exchange treatment, and tensile stress exists inside. Such chemically tempered glass has recently been used for a cover glass such as a touch panel in which end face strength is particularly required.

  Among the tempered glass, the present inventor has recently developed the following phenomenon, particularly when the surface is formed with an initial crack in the tempered glass having high strength and the scribe groove is formed by the laser scribe method. I found out that there might be a natural division.

  First, if an initial crack is formed at the edge of the glass substrate, which is the starting end of the scribe line, the initial crack is deeply formed in the scribe groove forming step. Then, due to the deep crack, the glass substrate is naturally divided without performing a dividing step after the scribe groove is formed.

  Further, as a measure for avoiding natural division, even if the initial crack is formed by being offset from the start end (the edge of the substrate) to the inner side, natural division may occur in the same manner. The phenomenon in this case will be described in more detail. First, in the step of forming a scribe groove, the crack may progress from the initial crack toward the edge of the glass substrate, contrary to the scanning direction of the laser beam. And when a crack progresses from an initial stage crack to the edge of a glass substrate, the depth of the crack of the edge part of a glass substrate will become so deep that it covers the whole substrate thickness. The glass substrate is naturally divided along the scribe groove by the deep crack formed in the edge portion. When such natural separation occurs, it becomes difficult to process the subsequent process.

  Therefore, it is conceivable to increase the amount of offset. However, when the amount of offset is increased, useless portions (portions that cannot be secured as products) increase in the peripheral edge portion of the glass substrate, resulting in poor yield.

  An object of the present invention is to prevent natural breakage of tempered glass by a simple method.

A scribing method for a glass substrate according to a first invention is a method for scribing a glass having a reinforcing layer having a compressive stress on its surface, an initial crack forming step, a scribe groove forming step, and a crack regulating groove forming step. And including. In the initial crack forming step, at least a part of the reinforcing layer is removed from the surface of the glass to form an initial crack. In the scribe groove forming step, the surface of the glass is heated by irradiating a laser beam, the heated region is cooled, and an initial crack is propagated along the planned scribe line to form a scribe groove. In order to prevent the initial crack from developing in the direction opposite to the crack propagation direction in the scribe groove forming process, the crack restricting groove forming process is performed as an initial crack on the surface of the glass as a pre-treatment or a post-treatment in the initial crack forming process. A groove having a predetermined width is formed between the edge of the glass substrate and a direction intersecting with a direction in which a planned scribe line extends.

Here, an initial crack is formed in the vicinity of the start end of the scribe line. Further, a groove is formed between the initial crack and the edge of the glass substrate for restricting the crack from developing in the reverse direction in a direction intersecting with the direction in which the scribe planned line extends. Thereafter, the glass surface is irradiated with laser light and heated, and the heated region is cooled. By this heating and cooling treatment, cracks develop along the scribe line and scribe grooves are formed. At this time, the crack propagates toward the end of the scribe line, but may also develop in the opposite direction. However, the crack progressing in the opposite direction is stopped by a groove formed between the initial crack and the edge of the glass substrate.

  For this reason, it can be avoided that the initial cracks propagate in the reverse direction and deep cracks are formed at the edge portions of the glass substrate. Therefore, the natural division after the scribe groove formation can be suppressed.

  In addition, since the formation of a crack from the initial crack toward the substrate edge can be regulated, the portion that cannot be secured as a product between the initial crack and the substrate edge can be reduced, and the yield of the product can be improved.

  The glass substrate scribing method according to a second aspect of the present invention is the scribing method of the first aspect, wherein in the crack restricting groove forming step, the groove is formed so as to extend in a direction perpendicular to the planned scribe line.

  Here, since the crack restricting groove is formed in a direction perpendicular to the scribe line, the progress of the crack can be stopped more reliably.

  In the scribing method for a glass substrate according to the third invention, in the scribing method of the first or second invention, in the crack regulating groove forming step, the groove is formed shallower than the depth of the scribe groove formed in the scribe groove forming step.

  Here, when the crack growth stopping groove is deepened, the crack may spontaneously progress from the crack growth stopping groove due to the tensile stress inside the glass substrate, and the substrate may be separated by this crack.

  Therefore, in the third aspect of the invention, the crack growth stopping groove is made shallower than the depth of the scribe groove so as to avoid natural division of the substrate.

The scribing method for a glass substrate according to a fourth invention is the scribing method of any one of the first to third inventions, wherein the initial crack formed in the initial crack forming step and the groove formed in the crack restricting groove forming step are , Formed with a gap between them,
Here, since the initial crack and the crack regulating groove are formed apart from each other, it is possible to more reliably suppress the initial crack from extending to the edge of the glass substrate.

As mentioned above, in this invention, it can suppress that an initial stage crack progresses in the reverse direction toward the edge of a glass substrate with respect to the glass which has the reinforcement | strengthening layer which gave the compressive stress on the surface. Therefore, it is possible to prevent the glass to break spontaneously at the point of forming the scribe groove in the glass.

The schematic block diagram of the apparatus for enforcing the scribe method by one Embodiment of this invention. The figure which shows a mode that a board | substrate isolate | separates naturally when scribing is implemented by the conventional method. 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 unit 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.

<Scribe device>
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 moves the irradiation unit 2 and the nozzle 4 of the cooling unit 3 relative to the glass substrate G along the scribe line SL set on the glass substrate G.

The irradiation unit 2 includes a laser oscillator (for example, a CO ₂ laser) that irradiates a laser beam LB, and irradiates the laser beam LB on the glass substrate G as a beam spot LS via an optical system.

  Although not shown here, an initial crack forming means for forming an initial crack TR serving as a starting point for scribing is provided at the end of the glass substrate G. As the initial crack forming means, a mechanical tool such as a cutter wheel is used, but it is also possible to form the initial crack TR by irradiation with a laser beam.

[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 initial crack forming means such as a cutter wheel. At this time, the depth of the initial crack TR is set to such a depth that the reinforcing layer formed on the surface of the glass substrate (tempered glass) is peeled off. Specifically, the depth of the initial crack TR is set to 1.0 to 2.0 times the thickness of the reinforcing layer.

  As a pre-process or a post-process of the above initial crack formation process, in the scribe groove forming process, which is the next process, the crack progresses from the initial crack TR in the direction opposite to the crack propagation direction (scanning direction of the laser beam LB). In order to prevent the development of cracks, a crack restricting groove S is formed. The groove S is formed between the initial crack TR and the edge Ge of the glass substrate G on the surface of the glass substrate G. Further, the groove S is formed with a predetermined width in a direction orthogonal to the direction in which the planned scribe line SL extends. Further, it is preferable that the depth of the crack restricting groove S is shallower than the depth of the scribe groove formed in the subsequent process. The reason for this is that if the crack growth stopping groove S is too deep, the crack will naturally grow starting from the crack growth stopping groove S due to the tensile stress inside the glass substrate and the substrate will be separated by this crack. is there. Further, the depth of the crack growth stopping groove S is preferably deeper than the thickness of the reinforcing layer.

  The crack restricting groove S is formed corresponding to each of the plurality of scribe lines SL. However, the crack restricting groove S may be a single groove orthogonal to all the scribe planned lines SL. However, in order to reduce foreign matter such as dust generated when forming the groove, it is preferable to form a plurality of grooves locally.

  Next, the laser beam LB is irradiated from the irradiation unit 2 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 2 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, a vertical crack is formed along the scheduled scribe line SL starting from the initial crack TR formed at the end of the glass substrate G, and a desired scribe groove is formed.

  Here, in the process of forming the scribe groove, even if the crack progresses from the initial crack TR in the direction opposite to the scanning direction of the laser beam LB, the crack is regulated between the initial crack TR and the edge Ge of the glass substrate G. Since the groove S is formed, the crack stops at the crack restricting groove S. For this reason, it is possible to avoid a crack from extending from the initial crack TR to the edge Ge of the glass substrate G and forming a deep crack at the edge of the glass substrate G. Thereby, it is possible to prevent the glass substrate G from being naturally divided.

Experimental example

[Verification of glass substrate cutting]
<Experimental example by conventional example>
FIG. 2 shows an example of a conventional method, that is, a case where laser heating and cooling are performed from the start end to the end end of the scribe line without forming the crack regulating groove S. The substrate is a tempered glass having an overall thickness of 0.7 mm and a reinforced layer thickness of 18 μm. Further, the laser beam conditions are a laser output of 200 W and a scanning speed of 200 mm / sec. In addition, in FIG. 2, the edge part area | region of a glass substrate does not appear.

  FIG. 2A shows a state immediately after scribing. Here, the scribe groove is in a state where it does not extend over the entire depth of the substrate (hereinafter, this state is referred to as “half cut”), and is represented by a thin line in the drawing.

  FIG. 2B shows a state after 5 seconds from the scribing process. Here, the scribe line is fully cut (shown as a dark line in the figure) from the scribe start point side (right side of the figure) to the center of the figure.

  FIG. 2C shows a state after 20 seconds from the scribing process. Here, the scribe line is fully cut (shown as a dark line in the figure) in all the parts shown in the figure.

  Thus, when laser heating and cooling are performed over the entire scribe line from the start end to the end end to form the scribe groove, the substrate is naturally divided (full cut).

<Example>
Compared to the conventional example as described above, by forming a groove S for crack control between the initial crack TR and the edge Ge of the glass substrate G, the initial crack TR toward the substrate edge Ge. The formation of cracks was prevented, and a full cut of the substrate, that is, a natural division could be avoided. The groove S was formed shallower than the depth of the scribe groove to be formed.

[Discussion on initial cracks]
In the method of the present embodiment, the depth of the initial crack or the like greatly affects the manufacturing quality. Therefore, an experimental example regarding the depth of the initial crack is shown below.

<Experimental example 1>
FIG. 3 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. 3 shows the relationship between the pressing load on the glass of the tool at the time of initial crack formation and the groove depth at that time, and the scribe 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. As cooling conditions, a cooling nozzle is disposed 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. 4, 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. 5 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, it can be seen that if the groove depth of the initial crack is about 24 to 50 μm (1.14 to 2.38 times the thickness of the reinforcing layer), a desired scribe groove is formed along the planned 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. 6 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, it can be seen that if the groove depth of the initial crack is about 24 to 60 μm (0.71 to 1.76 times the thickness of the reinforcing layer), a desired scribe groove is formed along the planned 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 in order to form a desired scribe groove along the scribe line, it is desirable that the depth of the initial crack is 1.0 to 2.0 times the thickness of the tempered glass reinforced layer. . 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 preferably at most 7% of the glass thickness.

[Feature]
(1) Since a groove S for regulating a crack perpendicular to the planned scribe line SL is formed between the initial crack and the substrate edge at the start end of the planned scribe line SL, the initial crack is formed. It is possible to prevent the crack from progressing toward the edge of the substrate. For this reason, it is possible to avoid the formation of a deep crack in the edge portion of the substrate, and it is possible to avoid the natural division of the substrate due to the deep crack. Therefore, subsequent processing steps such as cross scribing are facilitated.

  (2) Since the formation of a crack from the initial crack toward the substrate edge can be regulated, the offset amount of the initial crack from the substrate edge can be reduced. Therefore, the portion of the substrate that cannot be secured as a product is reduced, and the yield of the product can be improved.

  (3) Since the groove is formed as a means for stopping the crack from the initial crack toward the edge of the substrate, natural separation of the substrate can be avoided by a simple method.

  (4) Since the initial crack and the crack regulating groove are formed apart from each other, the crack from the initial crack toward the substrate edge can be stopped more reliably.

  (5) Since the crack restricting groove is locally formed, generation of dust or the like can be suppressed as much as possible, and deterioration of the quality of the glass substrate can be avoided.

[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 groove for controlling the crack is preferably formed so as to be orthogonal to the planned scribe line, but may not be orthogonal if it is formed so as to intersect the planned scribe line.

G Glass substrate
LB laser beam
LS beam spot
SL scribe line
CP cooling spot
TR initial crack
S Crack control groove

Claims (4)

The glass having a reinforcing layer which gave a compressive stress on the surface a scribing method for a glass substrate to be scribed,
An initial crack forming step of forming an initial crack by removing at least a part of the reinforcing layer on the surface of the glass ;
A scribe groove forming step of irradiating the surface of the glass with laser light to heat, cooling the heated region, and forming the scribe groove by extending the initial crack along the scribe line,
To prevent the initial crack to crack propagation direction and the reverse direction in the scribe groove forming step progresses, as a pretreatment or post-treatment of the initial crack formation process, the initial crack and the glass substrate on the surface of the glass A crack regulating groove forming step for forming a groove having a predetermined width in a direction intersecting with a direction in which a scribe planned line extends between the edge and the edge,
A method for scribing a glass substrate.   2. The glass substrate scribing method according to claim 1, wherein in the crack restricting groove forming step, the groove is formed to extend in a direction perpendicular to a scribe line.   3. The glass substrate scribing method according to claim 1, wherein in the crack restricting groove forming step, the groove is formed to be shallower than a depth of the scribe groove formed in the scribe groove forming step.   The initial crack formed in the initial crack forming step and the groove formed in the crack restricting groove forming step are formed with an interval between them. A scribing method for a glass substrate.