JP2012006795A - Cutting method and cutting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method etc. capable of precisely cutting a plate to be processed by use of a simple structure and improving the efficiency of use of the plate to be processed.SOLUTION: The cutting method comprises relatively moving an irradiation target region 101 of a laser beam 100 along at least a portion of a scribe line 12 formed on a surface 11 of the plate to be processed 10 so that a crack 202 is extended from the scribe line 12 ahead of the irradiation target region 101, thereby cutting the plate to be processed 10. Near an edge 14 of the plate to be processed 10 where the thickness t (mm) of the plate to be processed 10 and the minimum distance M (mm) between a tip 203 of the crack 202 on the scribe line 12 and the edge 14 of the plate to be processed 10 satisfy the relation: 0.4t≤M≤4t, the irradiation target region 101 is formed so that its length A (mm) in the transfer direction and its length B (mm) in the width direction satisfy the relations: 1/5×t≤B≤1/2×M and 0.2<A/B≤3.

Description

  The present invention relates to a cleaving method and a cleaving apparatus.

  As a typical cleaving method for a plate to be processed (brittle plate such as a glass plate), a method of cleaving the plate to be processed along the scribe line by applying a bending stress after processing a scribe line on the surface of the plate to be processed It has been known. In this method, when the bending stress is applied, the fractured surfaces are rubbed with each other, so that a large amount of cullet (glass waste) is generated, and the quality of the fractured surface may be deteriorated. In this method, it is difficult to apply bending stress depending on the shape of the scribe line.

  In order to solve this problem, the laser beam irradiation area is moved along the scribe line formed on the surface of the plate to be processed, and the cooling source is moved behind the irradiation area to move the workpiece. A cleaving method for cleaving a plate with thermal stress has been studied (see, for example, Patent Document 1). In this cleaving method, a part of the laser beam is absorbed by the work plate as heat in the irradiation region of the laser beam, and the temperature becomes higher than that of the surroundings, so that a compressive stress acts due to thermal expansion. On the other hand, a cooling gas is blown from the cooling source behind the laser light irradiation area, and the temperature becomes lower than that of the surrounding area. Therefore, tensile stress acts in a direction perpendicular to the scribe line, and a crack is formed. . The tip of the crack moves following the irradiation area of the laser beam.

Japanese Patent No. 3027768

  However, the conventional cleaving method requires a cooling source, a moving device that moves the cooling source, a control device that controls the moving device, and the like, which complicates the cleaving device. Moreover, in the conventional cleaving method, since there is a time lag between heating and cooling, the generation range of thermal stress becomes wide. As a result, the thermal stress balance in the in-plane direction and thickness direction of the work plate is lost, and the cleaving accuracy is reduced.

  In particular, when the vicinity of the edge of the workpiece plate is cleaved for the purpose of increasing the use efficiency of the workpiece plate, the thermal stress balance is likely to be lost. In this case, the heat capacities are greatly different on both sides of the scribe line.

  The present invention has been made in view of the above problems, and provides a cleaving method and a cleaving apparatus capable of cleaving a processed plate with a simple configuration with high accuracy and improving the use efficiency of the processed plate. The purpose is to provide.

In order to solve the above object, the cleaving method of the present invention is:
A cleaving method for cleaving the processed plate by irradiating a processed plate formed of a brittle material with a laser beam,
Relatively moving the irradiation region of the laser light along at least a part of a scribe line formed in advance on the surface of the workpiece plate;
Extend the crack ahead of the irradiated area from the scribe line,
When the shortest distance between the tip of the crack on the scribe line and the edge of the processed plate is M (mm) and the thickness of the processed plate is t (mm), 0.4 t ≦ M ≦ 4 t When the laser beam irradiates the scribe line near the edge of the workpiece plate that satisfies the relationship, the irradiation area has a length in the moving direction as A (mm) and a length in the width direction as B (mm). Then, it is formed so as to satisfy the relationship of 1/5 × t ≦ B ≦ 1/2 × M and 0.2 <A / B ≦ 3.

Moreover, in order to solve the above-mentioned object, the cleaving device of the present invention is
A cleaving device for cleaving the processed plate by irradiating a processed plate formed of a brittle material with a laser beam,
A stage that supports the workpiece plate, a light source that emits the laser beam, and a control device that moves an irradiation area of the laser beam on the surface of the workpiece plate,
The control device relatively moves the irradiation region of the laser light along at least a part of a scribe line previously formed on the surface, and extends a crack in front of the irradiation region from the scribe line,
When the shortest distance between the tip of the crack on the scribe line and the edge of the processed plate is M (mm) and the thickness of the processed plate is t (mm), 0.4 t ≦ M ≦ 4 t When the laser beam irradiates the scribe line near the edge of the workpiece plate that satisfies the relationship, the irradiation area has a length in the moving direction as A (mm) and a length in the width direction as B (mm). Then, it is formed so as to satisfy the relationship of 1/5 × t ≦ B ≦ 1/2 × M and 0.2 <A / B ≦ 3.

  According to the present invention, it is possible to provide a cleaving method and a cleaving apparatus that can cleave a work plate with a simple configuration with high accuracy and can increase the use efficiency of the work plate.

It is a side view of the cleaving apparatus in a 1st embodiment of the present invention. It is explanatory drawing which shows the relationship between the laser beam 100 and the irradiation area | region 101. FIG. 1 is a plan view of a glass plate 10. FIG. It is a figure of the modification of FIG. It is explanatory drawing (1) of the cleaving method using the cleaving apparatus. It is explanatory drawing (2) of the cleaving method using the cleaving apparatus. 6 is an explanatory diagram of stress generated at a tip 203 of a crack 202. FIG. It is explanatory drawing of the evaluation method of cleaving precision.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not restrict | limited to the below-mentioned embodiment, A various deformation | transformation and substitution can be added to below-mentioned embodiment, without deviating from the scope of the present invention.

  For example, in the embodiments described later, a glass plate is used as the plate to be processed, but a metal plate such as a silicon substrate or a ceramic plate may be used instead of the glass plate.

  FIG. 1 is a side view of a cleaving apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the relationship between the laser beam 100 and the irradiation region 101. FIG. 3 is a plan view of the glass plate 10 and shows the shape of the scribe line 12.

  As shown in FIGS. 1 and 2, the cleaving apparatus 20 includes a stage 30 that supports the glass plate 10, a light source 40 that emits laser light 100, and an irradiation region 101 of the laser light 100 on the surface 11 of the glass plate 10. And a control device 50 to be moved.

  In this cleaving device 20, as will be described in detail later, by relatively moving the irradiation region 101 of the laser light 100 along at least a part of the scribe line 12 formed in advance on the surface 11 of the glass plate 10, The glass plate 10 can be cleaved by thermal stress.

  The use of the product obtained by cleaving the glass plate 10 is not particularly limited, and examples thereof include architectural window glass, vehicle window glass, glass substrate for liquid crystal display (LCD), glass substrate for plasma display (PDP), and the like. It is done.

  The glass used for the glass plate 10 is appropriately selected according to the use of the product. For example, soda lime glass is used for architectural window glass, vehicle window glass, and PDP glass substrates. Further, non-alkali glass is used for the LCD glass substrate.

  As shown in FIG. 3, scribe lines 12 are formed in advance on the surface 11 of the glass plate 10. For example, as shown in FIG. 3, the scribe line 12 may be linear, and the start and end thereof may be at the edge 14 of the glass plate 10 or in the vicinity thereof.

  In the present embodiment, the scribe line 12 is linear, but the shape is not particularly limited. For example, as shown in FIG. 4, the scribe line 12A may have a curved shape, and the end thereof may intersect the middle of the scribe line 12A.

  A method of forming the scribe line 12 may be a general method, for example, a method using a cutter or a method using a laser beam. When using a cutter, the tip of the cutter is moved against the surface 11 of the glass plate 10 to form the scribe line 12. In this case, cutting oil may be applied to the glass surface in order to prevent chipping due to friction and to protect the scribe line. Moreover, when using a laser beam, the laser beam is irradiated to the surface 11 of the glass plate 10, the irradiation area | region is moved relatively along a cutting planned line, and the scribe line 12 is formed with a thermal stress.

  The stage 30 supports the back surface 13 of the glass plate 10. The stage 30 may support the entire back surface 13 of the glass plate 10 or may support a part of the back surface 13. The glass plate 10 may be adsorbed and fixed to the stage 30 or may be adhesively fixed to the stage 30.

  The light source 40 is a light source that emits the laser light 100 under the control of the control device 50. The light source 40 may be a CW laser that continuously oscillates the laser light 100, or may be a pulse laser that intermittently oscillates the laser light 100, and its oscillation method is not limited.

  Although it does not specifically limit as CW laser, For example, a high output and highly efficient semiconductor laser is used. For example, an Al-free and long-life InGaAsP semiconductor laser (wavelength: 808 nm, 940 nm) is preferably used.

  A condensing lens 44 that condenses the laser light 100 emitted from the light source 40 is provided in the optical path between the light source 40 and the stage 30. Laser light 100 emitted from the light source 40 is incident on the surface 11 of the glass plate 10 via the condenser lens 44.

  A mask 46 that defines the shape of the irradiation region 101 of the laser light 100 (hereinafter simply referred to as “irradiation shape of the laser light 100”) may be provided between the light source 40 and the stage 30. The mask 46 is made of a thin plate having an opening. The shape of the opening (and thus the irradiation shape of the laser beam 100) is not particularly limited, and examples thereof include a circular shape, an elliptical shape, and a rectangular shape.

  The light source 40, the condenser lens 44, and the mask 46 are incorporated in one processing head 70. The machining head 70 stands by above the stage 30 and is moved in the in-plane direction and the vertical direction of the stage 30 under the control of the control device 50. Therefore, the irradiation region 101 of the laser beam 100 and the condensing position 102 can be moved.

  In this embodiment, since the irradiation region 101 of the laser beam 100 is moved relatively, the processing head 70 side is moved. However, the stage 30 side may be moved, or both sides may be moved. good.

  The control device 50 is constituted by a microcomputer or the like. The control device 50 includes a movement control unit 51 that moves the irradiation region 101 of the laser light 100 and an intensity control unit 52 that controls the irradiation intensity of the laser light 100.

  The movement control unit 51 moves the irradiation area 101 of the laser beam 100 by controlling the position of the processing head 70 and the like. The intensity controller 52 controls the irradiation intensity of the laser light 100 by controlling the output of the light source 40 and the like. The control device 50 controls various operations of the cleaving device 20 described below.

  Next, a cleaving method using the cleaving apparatus 20 having the above configuration will be described with reference to FIGS. 5-6 is explanatory drawing of the cleaving method using the cleaving apparatus of FIG.

  As shown in FIG. 5, when the glass plate 10 is cleaved, first, the laser beam 100 is irradiated to the start end of the scribe line 12 or the vicinity thereof for a predetermined time (for example, 0.1 second). Then, in the irradiation region 101 of the laser beam 100, the temperature is higher than that of the surrounding area, so that compressive stress acts due to thermal expansion. As a reaction, tensile stress acts in the direction orthogonal to the scribe line 12 in front of the irradiation region 101 of the laser beam 100. As a result, an initial crack 200 is formed along the scribe line 12 from the edge 14 of the glass plate 10 to the front of the irradiation region 101 of the laser beam 100. The initial crack 200 penetrates the glass plate 10 in the thickness direction at least at the edge 14 of the glass plate 10 and its vicinity.

  Subsequently, as shown in FIG. 6, the irradiation region 101 of the laser beam 100 is moved relatively along the scribe line 12, and the crack 202 is extended from the scribe line 12 “in front” of the irradiation region 101. The crack 202 is formed by extending from the tip 201 of the initial crack 200, and the tip 203 of the crack 202 is positioned in front of the irradiation region 101.

  Thereafter, when the irradiation region 101 of the laser beam 100 approaches the end of the scribe line 12, the crack 202 reaches the edge 14 of the glass plate 10 to divide the glass plate 10, and the cleaving of the glass plate 10 is completed.

  Thus, in this embodiment, since the cooling source used in the conventional general cleaving method, the moving device that moves the cooling source, the control device that controls the moving device, and the like are unnecessary, the cleaving device is simplified. be able to. Further, in the present embodiment, the glass plate 10 is cleaved by extending the crack 202 from the scribe line 12 “in front” of the irradiation region 101 of the laser beam 100, so that the generation range of the thermal stress becomes wide. Can be suppressed. Therefore, good cleaving accuracy can be obtained.

  In the present embodiment, the laser beam 100 is irradiated to the start end of the scribe line 12 or the vicinity thereof for a predetermined time to form the initial crack 200, but the present invention is not limited to this. By optimizing the irradiation shape and irradiation intensity of the laser light 100, the initial crack 200 and the crack 202 can be formed without stopping the movement of the laser light 100.

  Next, preferable conditions for the laser beam 100 will be described.

  The wavelength of the laser beam 100 is appropriately set according to the physical properties and shape of the glass plate 10. For example, when the glass used for the glass plate 10 is soda lime glass, the wavelength of the laser light 100 is preferably one or more predetermined wavelengths within the range of 795 to 1030 nm. If it is longer than 1030 nm, it is difficult to produce a semiconductor laser having a high output (for example, 100 W or more).

  If the wavelength of the laser beam 100 is too long, most of the laser beam 100 is absorbed as heat near the surface 11 of the glass plate 10. As a result, since glass generally has a low thermal conductivity, the surface 11 of the glass plate 10 is overheated and the interior of the glass plate 10 does not reach a sufficiently high temperature. Therefore, sufficient tensile stress is not generated inside the glass plate 10, and the cleaving accuracy is lowered.

  Moreover, when the surface 11 of the glass plate 10 is overheated, the cutting oil used when forming the scribe line 12 burns. Since the carbide after combustion absorbs most of the laser beam 100, it further promotes overheating of the surface 11 of the glass plate 10.

  Further, when the surface 11 of the glass plate 10 is overheated, cracks extend in a direction intersecting the scribe line 12 with a lateral crack generated when the scribe line 12 is formed as a base point. It occurs in large quantities and the cleaving accuracy decreases.

  On the other hand, if the wavelength of the laser beam 100 is too short, most of the laser beam 100 is transmitted through the glass plate 10, so that it is difficult to obtain a thermal stress sufficient for cleaving.

  The condensing position 102 of the laser light 100 is preferably shifted to the opposite side of the light source 40 or the light source 40 side as shown in FIG. 2 with respect to the surface 11 of the glass plate 10. Thereby, it can suppress that the surface 11 of the glass plate 10 is overheated.

  The irradiation intensity of the laser beam 100 is set according to the physical properties and shape of the glass plate 10, the dimensional shape of the scribe line 12, the irradiation position and irradiation shape of the laser beam 100, the moving speed, and the like. The irradiation intensity of the laser beam 100 is set so that the crack 202 extends, and the glass temperature in the irradiation region 101 of the laser beam 100 is set to be lower than the annealing point of the glass. When the temperature is higher than the annealing point, the glass flows in a viscous manner so as to relieve the thermal stress, so that it is difficult to cleave the glass plate 10.

  By the way, for the purpose of improving the use efficiency of the glass plate 10, the vicinity of the edge 14 of the glass plate 10 may be cleaved, for example, as shown in FIG. In this case, the presence of the edge 14 affects the cleaving accuracy.

Therefore, in this embodiment, when the shortest distance between the tip 203 of the crack 202 on the scribe line 12 and the edge 14 of the glass plate 10 is M (mm), and the thickness of the glass plate 10 is t (mm). In the vicinity of the edge 14 of the glass plate 10 that satisfies the relationship of 0.4t ≦ M ≦ 4t, the irradiation region 101 is formed so as to satisfy the relationship of the following formulas (1) and (2).
1/5 × t ≦ B ≦ 1/2 × M (1)
0.2 <A / B ≦ 3 (2)
In Equation (1) and Equation (2), the movement direction length of the irradiation region 101 is A (mm), and the width direction length of the irradiation region 101 is B (mm).

  As shown in the above formula (1), the thermal stress necessary for cleaving can be applied to the glass plate 10 by setting the width direction length B to 1/5 × t or more. On the other hand, when the width direction length B exceeds 1/2 × M, the edge 14 of the glass plate 10 is overheated, and an unintended crack is formed between the edge 14 and the scribe line 12. The length B in the width direction may be constant during the cleaving or may vary as long as the relationship of the above formula (1) is satisfied.

  When, for example, an automotive window glass is cut out from a work plate, a central product portion and an unused portion at the periphery of the central portion are generated as shown in FIG. In the cleaving, the beginning and end of the cleaving may be located in this discard margin area. The conditions of the above formulas (1) and (2) do not need to be applied when the start and end of the cleaving are located in the discard margin area. This is because there is no problem as a product even if the cleaving quality of the discarded part decreases. Therefore, the conditions of the above formulas (1) and (2) may be applied when cleaving at least the outer shape of the workpiece plate to be a product. In FIG. 3, for the purpose of explaining the present invention, only one straight line is cleaved, and the width direction length B is set near the cleaving start end and near the end with the shortest distance M as W1 as in the cleaving center vicinity. ing.

  By the way, the crack 202 mainly extends under the influence of three stresses shown in FIG. The stress shown in FIG. 7A is a tensile stress acting in a direction orthogonal to the scribe line 12. The stress shown in FIG. 7B is a shear stress acting in the in-plane direction of the glass plate 10. The stress shown in FIG. 7C is a shear stress that acts in the out-of-plane direction of the glass plate 10.

  Among these stresses, when the influence of the tensile stress shown in FIG. 7 (a) becomes dominant, the cut surfaces are not easily rubbed, so that cullet is hardly generated. Moreover, since the crack 202 is difficult to twist, it is difficult to come off from the scribe line 12.

  In particular, in the vicinity of the edge 14 of the glass plate 10, the difference in heat capacity between both sides of the scribe line 12 is large, and the thermal stress balance is likely to be lost. Therefore, it is necessary to make the influence of tensile stress dominant.

  Therefore, in this embodiment, A / B is set to 3 or less as shown in the above formula (2) so that the influence of tensile stress becomes dominant. When A / B exceeds 3, the thermal stress balance in the moving direction tends to be lost, and the influence of the shear stress shown in FIGS. 7B and 7C becomes dominant. A / B is appropriately set according to the thickness t and the like, but is preferably 2 or less, more preferably less than 1 and even more preferably less than 0.7.

  On the other hand, when A / B is 0.2 or less, the irradiation area of the laser beam 100 becomes too small. Therefore, when the thermal stress necessary for cleaving is applied to the glass plate 10, the surface 11 of the glass plate 10 is overheated. There is a problem that the cutting oil burns. Further, when A / B is 0.2 or less, when the thermal stress necessary for cleaving is applied to the glass plate 10, the surface 11 of the glass plate 10 is overheated and cracks are formed in the direction intersecting the scribe lines 12. There are problems such as extension. Therefore, A / B is preferably more than 0.2, more preferably 0.5 or more, as shown in the above formula (2).

  Further, in the vicinity of the edge 14 of the glass plate 10 that satisfies the relationship of 0.4t ≦ M ≦ 4t, the irradiation region 101 of the laser beam 100 may be formed to satisfy the relationship of 1 ≦ A ≦ 10. preferable. By setting the moving direction length A to 1 mm or more, it is possible to apply the thermal stress necessary for cleaving to the glass plate 10 and to suppress the surface 11 of the glass plate 10 from being overheated.

  On the other hand, if the moving direction length A exceeds 10 mm, the irradiation area is too wide, and the heating efficiency by the laser beam 100 is poor. Further, there is a problem that the thermal stress balance is easily lost in both the moving direction and the width direction, and the influence of the shear stress shown in FIGS. 7B and 7C becomes dominant.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Example 1)
In Example 1 (Example), the cleaving apparatus 20 shown in FIGS. 1 and 2 was used to cleave the glass plate 10 on which the scribe line 12 shown in FIG. 3 was formed by the cleaving method shown in FIGS. 5 and 6. . The glass plate 10 is made of green soda lime glass for vehicle window glass, and the shape of the glass plate 10 is 500 mm long × 500 mm wide × 5 mm thick.

  The scribe line 12 was formed by rolling at a moving speed of 100 mm / sec while pressing the tip (tip angle 155 °) of the diamond wheel cutter against the surface 11 of the glass plate 10 with a force of 90 N. The scribe line 12 was parallel to one side of the glass plate 10, and the widths W1 and W2 (see FIG. 3) of the glass on both sides of the scribe line 12 were 10 mm and 490 mm, respectively.

  A CW laser was used as the light source 40 of the laser light 100. Specifically, a semiconductor laser (laser light wavelength: 808 nm) was used. The output of the light source 40 was constant at 300W. The irradiation shape of the laser beam 100 was a rectangular shape symmetrical with respect to the scribe line 12, the moving direction length A was 7.5 mm, and the width direction length B was 3 mm.

  As shown in FIG. 5, the initial crack 200 was formed by irradiating the start end of the scribe line 12 with the laser beam 100 for 0.4 seconds. Next, as shown in FIG. 6, the irradiation region 101 of the laser light 100 is moved at a relative speed of 30 mm / second along the scribe line 12, so that the crack from the scribe line 12 is “frontward” of the irradiation region 101. 202 was extended and a cleaving test was conducted.

(Examples 2 to 9)
In Examples 2 to 7 (Example) and Examples 8 to 9 (Comparative Example), the type of the mask 46 is changed to adjust the irradiation shape of the laser light 100, and the moving speed of the laser light 100 is adjusted to 20 according to the adjustment. A cleaving test was conducted in the same manner as in Example 1 except that the range was changed within the range of ˜200 mm / sec.

(Example 10)
In Example 10 (comparative example), the irradiation shape and moving speed of the laser beam 100 and the output of the light source 40 are changed, and the crack 202 is extended from the scribe line 12 “backward” of the irradiation region 101 of the laser beam 100. Otherwise, the cleaving test was conducted in the same manner as in Example 1. Note that the irradiation shape of the laser light 100 was a circular shape having a diameter of 2 mm, and the moving speed of the laser light 100 was 70 mm / second. The output of the light source 40 was constant at 120W.

  Table 1 shows the conditions and results of these cleaving tests. In addition, the result was evaluated by the possibility of cleaving and the quality of the fractured surface. Those that could be cleaved were marked with ◯, and those that could not be cleaved were marked with x. The quality of the fractured surface was evaluated by the inclination S of the fractured surface 15 shown in FIG. A sample having an inclination S of 0.5 mm or less was evaluated as ◯, a sample having an inclination S exceeding 0.5 to 1.0 mm was evaluated as Δ, and a sample having an inclination S exceeding 1.0 mm was evaluated as ×.

表１から、レーザ光１００の照射領域１０１よりも「前方」でスクライブ線１２から亀裂をさせた場合、割断面の品質が良いことが分かる。また、比（Ａ／Ｂ）が０．２超〜３以下の範囲内にあると、割断面１５の品質がさらに良いことが分かる。なお、例９では、ガラス板１０の表面１１が過熱されて切削油が燃焼しないように、移動速度を２００ｍｍ／秒としたので、移動速度が速すぎ、割断に十分な熱量をガラス板１０に与えることができなかった。

From Table 1, it can be seen that when the crack is made from the scribe line 12 "in front" of the irradiation region 101 of the laser beam 100, the quality of the split section is good. Moreover, it turns out that the quality of the cut surface 15 is still better when the ratio (A / B) is in the range of more than 0.2 to 3 or less. In Example 9, since the moving speed was set to 200 mm / second so that the surface 11 of the glass plate 10 was not overheated and the cutting oil was not burned, the moving speed was too high and a sufficient amount of heat was applied to the glass plate 10 for cutting. Couldn't give.

10 Glass plate (work plate)
11 Front surface 12 Scribe line 13 Back surface 14 Edge 15 Split section 20 Cutting device 30 Stage 40 Light source 50 Control device 100 Laser light 101 Irradiation area 200 Initial crack 201 Initial crack tip 202 Crack 203 Crack tip

Claims (4)

A cleaving method for cleaving the processed plate by irradiating a processed plate formed of a brittle material with a laser beam,
Relatively moving the irradiation region of the laser light along at least a part of a scribe line formed in advance on the surface of the workpiece plate;
Extend the crack ahead of the irradiated area from the scribe line,
When the shortest distance between the tip of the crack on the scribe line and the edge of the processed plate is M (mm) and the thickness of the processed plate is t (mm), 0.4 t ≦ M ≦ 4 t When the laser beam irradiates the scribe line near the edge of the workpiece plate that satisfies the relationship, the irradiation area has a length in the moving direction as A (mm) and a length in the width direction as B (mm). Then, the cleaving method is characterized by being formed so as to satisfy the relationship of 1/5 × t ≦ B ≦ 1/2 × M and 0.2 <A / B ≦ 3.   When irradiating the scribe line near the edge of the processed plate with laser light that satisfies the relationship of 0.4t ≦ M ≦ 4t, the irradiation region is formed so as to satisfy the relationship of 1 ≦ A ≦ 10. The cleaving method according to claim 1. A cleaving device for cleaving the processed plate by irradiating a processed plate formed of a brittle material with a laser beam,
A stage that supports the workpiece plate, a light source that emits the laser beam, and a control device that moves an irradiation area of the laser beam on the surface of the workpiece plate,
The control device relatively moves the irradiation region of the laser light along at least a part of a scribe line previously formed on the surface, and extends a crack in front of the irradiation region from the scribe line,
When the shortest distance between the tip of the crack on the scribe line and the edge of the processed plate is M (mm) and the thickness of the processed plate is t (mm), 0.4 t ≦ M ≦ 4 t When the laser beam irradiates the scribe line near the edge of the workpiece plate that satisfies the relationship, the irradiation area has a length in the moving direction as A (mm) and a length in the width direction as B (mm). Then, the cleaving device is formed so as to satisfy the relationship of 1/5 × t ≦ B ≦ 1/2 × M and 0.2 <A / B ≦ 3.   When irradiating the scribe line near the edge of the processed plate with laser light that satisfies the relationship of 0.4t ≦ M ≦ 4t, the irradiation region is formed so as to satisfy the relationship of 1 ≦ A ≦ 10. The cleaving device according to claim 3.

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