KR20110106360A - Splitting apparatus and cleavage method for brittle material - Google Patents

Abstract

As a laser light source, a highly versatile CO ₂ laser light source can be used, and the splitting device of brittle material that can significantly cut the cutting speed and cut the full body in a straight straight line without bending the cut surface with respect to the cut schedule line. To provide. The rows of the first beam irradiation region 13, the second beam irradiation region 14, and the cooling point 15 are relatively moved along the cutting schedule line 12 of the glass substrate 11. The first beam irradiation region 13 is located in front of the second beam irradiation region 14 in the cutting direction, and the second beam irradiation region 14 is a thin and long beam along the cutting schedule line, and cooled. The point 15 is disposed at a position separated by a predetermined position from the rear end of the second beam irradiation area 14.

Description

Splitting device and cutting method of brittle material {SPLITTING APPARATUS AND CLEAVAGE METHOD FOR BRITTLE MATERIAL}

The present invention relates to a splitting apparatus and a cutting method of a brittle material for full-body cutting a brittle material, in particular a glass for a flat panel display. Hereinafter, although glass is mentioned as an example of a brittle material, this invention is generally applicable to brittle materials, such as quartz, a ceramic, a semiconductor, in addition to glass.

In the recent glass cutting, a thermal stress scribe method (hereinafter abbreviated as laser scribe) by laser light irradiation has been used instead of the mechanical method by diamond chips which has been used for the past century.

According to the laser scribe, it is possible to eliminate the inherent drawbacks of the mechanical method, namely, the decrease in the glass strength due to the generation of microcracks, the contamination due to the generation of cullets during cutting, the presence of the lower limit of the applied plate thickness, and the like.

The principle of the laser scribe is as follows. Only heating is locally generated on the glass, and laser light irradiation is performed so that vaporization, melting, and cracking do not occur. At this time, the glass heating part tries to thermally expand, but due to the reaction from the surrounding glass, sufficient expansion is impossible, and compressive stress occurs around the irradiation point. Even in the surrounding non-heating region, distortion is caused to the periphery further by being pushed by the expansion from the heating portion, and as a result, compressive stress occurs. This compressive stress is radial. By the way, when there is compressive stress in an object, the tensile stress which concerns on Poisson's ratio generate | occur | produces in the orthogonal direction. Here, the direction is a tangential direction. This state is shown in FIG.

Fig. 9 shows changes in the radial stress component σ _x and the tangential stress component σ _y when there is a temperature rise in the Gaussian distribution centered on the origin. The radial stress component (σ _x ) is the longitudinal compressive stress (negative value in FIG. 9), but the tangential stress component (σ _y ) is the compressive stress at the heating center (distance r = 0), but is out of the heating center. It is changed to the plane tensile stress (plus value in FIG. 9).

Among these stresses, tensile stress is related to cutting. When the tensile stress exceeds the fracture toughness value that is the material intrinsic value, fracture occurs everywhere and becomes uncontrollable. In the case of the laser cutting method, since the tensile stress is selected below this fracture toughness value, fracture does not occur.

By the way, when there exists a crack in the tensile stress presence position, a stress enlargement will generate | occur | produce in this crack tip, and a crack will expand when the stress intensity | strength coefficient by this stress exceeds the fracture toughness value of a material. That is, a controlled split is created. Therefore, the crack can be extended by scanning the laser irradiation point.

The laser scribing method of this glass was developed for the first time by Gondola Tenco, and the Japanese patent of patent document 1 is established. The principle of the laser cutting method by patent document 1 is shown to FIG. 10 (a). CO ₂ laser light is used as the laser light, and 99% of the energy in the beam spot 1 of the CO ₂ laser light is absorbed in the glass surface layer having a depth of 3.7 μm of the glass 2, Does not penetrate through the entire thickness. This is due to the absorption coefficient of the glass of the CO ₂ laser wavelength remarkably large. The depth by a laser scribe is about 100 micrometers normally, even if it helps with the heat conduction 4 in the glass 2.

The glass 2 is brittle and can be mechanically cut by applying a stress in accordance with this scribe line. The process of total cutting by application of this mechanical stress is called a brake. That is, in the case of employing the laser scribing method, a post-stroke called a brake is indispensable in order to break up the glass, and since the brake process is necessary, practicality is limited and diffusion is not necessarily perfect.

Considering the desire to completely separate the glass using a laser beam, a laser scribe is not always sufficient because a post-process called brake is added to the laser scribe. What is expected to be required here is the technique of full body splitting using a laser beam. However, in Patent Literature 1, there are some drawbacks as described later in the full body splitting, and the claim that the laser scribing technique is superior is made, indicating a negative position on the effectiveness of the full body splitting.

As another prior document regarding the technique of a laser scribe, in patent document 2, the laser beam is irradiated on a glass substrate, and the elliptical laser spot LS1 extended in the Y-axis direction along the scanning direction of a glass substrate, and the X-axis It is described that the elliptical laser spot LS2 elongated in the direction is formed to be separated by a predetermined distance. However, the purpose of the invention described in Patent Literature 2 is not intended to be a full body cutting at all, but is intended to perform stable laser scribing to the last.

On the other hand, when irradiated with laser light 5 which is transmitted through the glass 2 as shown in FIG. 10 (b) and a part thereof is absorbed, the transmitted light is divided by the total thickness of the glass 2 6. ), The glass 2 can be cut by only this process, and the brake is unnecessary. This split is called a full body split by a laser.

In addition to the technical features of the laser cutting method described above, the full body cutting results in a merit peculiar to the full body cutting, such that brakes are not required and free-cut cutting can be performed. You can make improvements. The applicant of this application proposes patent documents 3, 4, etc. about this full-body cutting technique.

Japanese Patent No. 3027768 Japanese international publication 03/008168 brochure Japanese Patent Publication No. 2007-76077 Japanese Patent Publication No. 2007-261885

Since the cutting according to Patent Literature 1 is not a full body cutting, it is necessary to apply a brake step to limit practicality as described above. In Patent Document 3, the full-body haldan by laser proposed in 4 technology, in the case where the high CO ₂ laser light versatility as a laser light source, it is not so discard most are absorbed by the surface of the glass can be directly applied . In addition, as pointed out in Patent Literature 1 in the full-body cutting technique, when the cutting position is separated from the work end by the so-called size effect, the cutting speed is remarkably decreased, and when the cutting position is close to the end of the glass, the cutting section is There is a drawback to bending. The defect by this size effect is demonstrated by FIG.

First, the low speed which is the 1st drawback of full-body cutting of glass is demonstrated. In FIG. 11A, the case where the glass plate 2 is cut in a state where the widths W ₁ and W ₂ are large is considered. When the laser light 5 is scanned in the dividing direction 3 along the dividing line 7, the tensile force is generated in the glass plate 2 by the above-described principle by heating by laser light irradiation, and the glass plate 2 is It is cut along the scanning trajectory of the laser light 5. In Fig. 11 (a), this deformation is exaggerated and the actual movement of the glass after cutting is about several microns.

At this time, when the widths W ₁ and W ₂ of the glass plates 2 on both sides of the cut line 7 are large, the scanning speed of the laser light 5 decreases remarkably. Firstly, the tensile stresses F ₀ and F ₁ necessary for cutting the glass plate 2 must overcome the resistance to the above-described deformation. This resistance will act on the area of the glass plate (2), and significantly increased in the case where the largest width (W ₁ and W ₂₎ of the glass plate (2). Since the cutting of the glass plate 2 must be performed in response to a large resistive force, it is necessary to make the scanning speed of the laser beam 5 small, and to increase the heating amount by the laser beam 5 relatively.

As a result, since the scanning speed of the laser beam 5 must be made low speed, the cutting speed is naturally limited. This tendency is more pronounced as the distance between the position of the cut line 7 and the end of the glass plate 2 is large, that is, the width W ₁ and W ₂ of the glass plate 2 after cutting in FIG. Do. For example, in the case where the widths W ₁ and W ₂ of the glass plate 2 after the cutting are a distance of 500 mm, if the scanning speed of the laser light 5 is not set to a significantly small speed of about 10 mm / s, the pull The body can not be divided.

Next, the fact that the cut surface of the brittle material, which is another drawback of the full body cut of the brittle material, is curved with respect to the predetermined cut position will be described. As described with reference to FIG. 11A, the splitting when the laser light 5 is scanned in the cutting direction 3 along the cutting line 7 causes the tensile stresses F ₀ and F ₁ to act on the glass plate 2. ) In the creeping direction. At this time, if there is an imbalance in the above-mentioned resistance to both sides, a force to bend the cutting section with respect to the cutting line. This aspect is shown to FIG. 11 (b). In Fig. 11 (b), when the width W ₃ is small, the resistance force on the width W ₃ side is small, so that the curved surface is largely curved, and the cut section after cutting is bowed and curved. This tendency is remarkable when the widths W ₁ and W ₃ of the glass plate 2 after cutting are unbalanced, especially when one width W ₃ is particularly small. Also in this case, as described above, the deformation of the work is markedly exaggerated than that of the actual few microns.

The present invention solves the problems of the prior art, while realizing the high quality of the thermal stress cutting by the laser, while significantly increasing the cutting speed, the cutting surface is straight without a curve to the cutting line. It is an object of the present invention to provide a device for dividing a brittle material capable of full body cutting and a cutting method.

The splitting apparatus of the brittle material according to the present invention heats the brittle material along the cut schedule line from the initial crack side formed on the cut schedule line, and the cut schedule line with respect to the cut schedule line assumed for the brittle material. An apparatus for dividing a brittle material by moving a position to be heated along a relatively, comprising: laser beam irradiation means for irradiating a laser beam to the brittle material along a cut line to generate a heated portion; And cooling means for locally cooling the brittle material at a position behind the heating portion with respect to the movement direction along the cut line, wherein the laser beam irradiation means is forward of the movement direction to the heating portion. A first beam irradiator that forms a first laser beam irradiated region located at and the first laser to the heated portion And a second beam irradiation part forming a second laser beam irradiation area having an elongated shape along the cutting line in the rear of the moving direction of the beam irradiation area.

In the apparatus for dividing brittle material according to the present invention, the laser power applied to the first laser beam irradiation area formed by the first beam irradiation part is directed to the second laser beam irradiation area formed by the second beam irradiation part. It is preferable that it is larger than the laser power provided. According to this structure, the heat energy necessary for segmenting a brittle material can be provided efficiently with respect to a brittle material.

Moreover, in the splitting apparatus of the brittle material which concerns on this invention, the laser power density of the 1st laser beam irradiation area | region formed by the said 1st beam irradiation part is the 2nd laser beam irradiation area | region formed by the said 2nd beam irradiation part. It is preferable that the laser power density is lower than. According to this structure, the surface energy of a brittle material does not melt but can provide the heat energy required in order to segment a brittle material.

Moreover, in the splitting apparatus of the brittle material which concerns on this invention, the position of the 1st laser beam irradiation area | region formed by the said 1st beam irradiation part is a position away from the rear end of the said 2nd laser beam irradiation area to the said cooling means. The distance in the direction along the above-mentioned cutting line may be variable with respect to the cooling position formed by cooling locally. According to this structure, the temporal state of the thermal diffusion inside the brittle material can be changed.

In this case, the distance between the position of the first laser beam irradiation area and the cooling position may be set based on at least one of the cutting speed and the thickness of the brittle material. According to this structure, the time until the brittle material heated in the 1st laser beam irradiation area | region is started to cool, and / or the time until the temperature conduction by thermal diffusion to the back surface of a brittle material can be adjusted and set.

Moreover, in the splitting apparatus of the brittle material which concerns on this invention, the shape of the said 1st laser beam irradiation area may be substantially circular. According to this structure, the laser beam irradiated from the 1st beam irradiation part can be used as it is or just changing the beam diameter.

Moreover, in the division | segmentation apparatus of the brittle material which concerns on this invention, the shape which divided | segmented the center part whose shape of the said 1st laser beam irradiation area | region is substantially circular into a predetermined width may be sufficient. According to this configuration, the linearity of the cut section can be improved.

In this case, the 1st laser beam which forms the said 1st laser beam irradiation area may be produced by arrange | positioning the shield of predetermined width in the center part of the optical path of the laser beam from the said 1st beam irradiation part. According to this structure, the irradiation area shape of the 1st laser beam can be made into the shape which divided | segmented the substantially circular center part by predetermined width in a very simple method.

Moreover, in the splitting apparatus of the brittle material which concerns on this invention, the 2nd laser beam which forms the said 2nd laser beam irradiation area is a laser beam from the laser light source of the said 2nd beam irradiation part. It may be produced by passing through a lens to shaping. According to this structure, the irradiation position shape of the 2nd laser beam can be made non-circular by a very simple method.

In addition, the apparatus for dividing a brittle material according to the present invention, further comprising: initial crack forming means for forming an initial crack at an end portion of the split schedule line of the brittle material, wherein the first beam irradiating portion and the second beam irradiating portion are initially cracked. You may move along the said cutting | disconnection predetermined line from the position of. According to this configuration, the start of crack expansion for cutting the brittle material can be performed at a low threshold.

Moreover, in the splitting apparatus of the brittle material concerning this invention, the said laser beam irradiation means distribute | distributes 50% or more of laser power to a said 1st beam irradiation part, and distributes less than 50% of laser power to a said 2nd beam irradiation part. A beam splitter may be included. According to this structure, one laser beam apparatus is enough and cost can be reduced.

The cutting method of the brittle material according to the present invention is a brittle material for heating the brittle material along the cutting schedule line of the brittle material, and moving the brittle material and the heating position relatively along the cutting schedule line to cut the brittle material. In the splitting method, an initial crack is formed at an end of a brittle material on the splitting schedule line, and heating of the brittle material is performed by a first laser beam and a second laser beam using the initial crack as a starting point. The laser beam is a beam located in the forward direction of the movement direction along the splitting line with respect to the second laser beam, and the second laser beam is an elongated beam along the splitting line, and the second And locally cool the position away from the rear end of the laser beam by a predetermined position.

As the first and second laser beams in the present invention, for example, a CO ₂ laser generally used for a surface laser scribe can be used. When the brittle material is cut by the second laser beam, the first laser beam heats the front of the predetermined cut position so that the heat energy of the second laser beam is efficiently conducted thermally in the thickness direction of the brittle material, and then the predetermined By cooling the position, cracks that extend to the rear surface of the brittle material directly under the cooling position occur. Therefore, by moving the first beam irradiator, the second beam irradiator, and the cooling means relatively along the predetermined cutting position of the brittle material, the brittle material is to be cut by heating by the first and second laser beams, followed by cooling. The full body can be split along the position.

In this manner, according to the present invention, the full-body cutting speed of the brittle material can be significantly increased as compared with the prior art while realizing the high quality of the thermal stress cutting by the laser. In addition, the brittle material can be separated over almost the entire length of the processing length only by the thermal stress caused by the laser, so that the generation of collites due to the brake process can be significantly suppressed. Further, the cut section can be cut in a straight line without being curved with respect to the cut schedule line.

1 is a conceptual diagram showing the positional relationship and temperature characteristics of a laser beam for explaining the principle of the method of cutting brittle material according to the present invention, (a) is the irradiation position of the first laser beam, the second laser beam The conceptual plan view which shows the mutual positional relationship of an irradiation position and a cooling position, (b) is when the heating by the 1st laser beam and 2nd laser beam in FIG. 1 (a) superimposed on the glass substrate surface. The figure which shows a temperature profile, (c) is a conceptual top view explaining the phenomenon by the position shift of the 1st laser beam and the 2nd laser beam in FIG. 1 (a).
2 is a conceptual perspective view of an essential part for explaining the principle of the cutting method of brittle material according to the present invention.
It is a conceptual diagram which shows the structure of the cutting device in Example 1 of the cutting method of the brittle material which concerns on this invention.
4 is a cross-sectional conceptual view of a main part for explaining in detail the principle of the brittle material cutting method according to the present invention, (a) is a cross-sectional conceptual view, (b) is a cross-sectional view taken along the line AA 'of FIG. .
It is a perspective view explaining the cut surface of the glass substrate cut | disconnected by the cutting method of the brittle material which concerns on this invention.
It is a conceptual diagram which shows the structure of the cutting device in Example 2 of the cutting method of the brittle material which concerns on this invention.
Fig. 7 is a conceptual diagram showing the positional relationship and temperature characteristics of the laser beam in the second embodiment of the method for cutting brittle materials according to the present invention, (a) is the irradiation position of the first laser beam and the second laser beam. The conceptual plan view which shows the mutual positional relationship of the irradiation position and cooling position of (b), when the heating by the 1st laser beam and the 2nd laser beam in FIG.7 (a) superposed on the glass substrate surface It is a figure which shows the temperature profile.
8 is a temperature plotting the state of the temperature change inside the glass over time when an initial heat amount is applied to one side of the non-alkali glass having a thickness of 0.7 mm in the embodiment of the method for cutting brittle materials according to the present invention. It is a distribution graph.
Fig. 9 illustrates the radial stress component (σ _x ) and the tangential stress component (σ _y ) in the case where there is a temperature rise of a Gaussian distribution centered on the origin for explaining the thermal stress generation principle of the laser cutting method. A characteristic diagram showing a change.
It is a conceptual perspective view explaining the laser cutting method of the conventional glass, (a) is a surface scribe, (b) is a schematic diagram at the time of a full cut.
Fig. 11 is a conceptual perspective view illustrating the size effect in the conventional laser cutting method of glass. (A) shows a case where the split widths on both sides of the glass plate are large, and (b) shows a case where the split width on one side of the glass plate is small. It is a figure which shows.
It is a figure which shows the processing test result of the full body cutting using the non-alkali glass of thickness 0.7mmt.

EMBODIMENT OF THE INVENTION Hereinafter, the principle and embodiment of this invention are demonstrated in detail with drawing. In the following description, a glass substrate is demonstrated as an example as a brittle material.

FIG. 3: shows typically the structure of the glass substrate full cut apparatus which is one Embodiment of this invention. The glass substrate 11 is mounted on the movable table 32, and the movable table 32 moves in an X-Y plane by an X-Y drive apparatus. In the figure, only the servo motor 33 and the shaft shaft for Y-axis drive which are the moving directions of glass are shown, and the illustration of the X-axis drive system is omitted.

In the present embodiment, two laser oscillators for heating the glass are used, a CO ₂ laser 21 and a CO ₂ laser 25. The laser beam 22 emitted from the CO ₂ laser 21 is vertically reflected by the reflector 23 and shaped to have a predetermined beam diameter through the condenser lens 24. Further, the beam passing through the condenser lens 24 is irradiated to the surface of the glass substrate 11 as it is. In some cases, the beam shield 35 (see FIG. 6) as a beam attenuating portion is placed on the beam transmission path. By arranging, the shape of a beam is partially changed. In any case, the first beam irradiation region by the first laser beam is formed on the glass substrate 11 by the laser beam 22. The position where the 1st beam irradiation area | region on the glass substrate 11 is formed is moved and the position of the reflection angle of the reflecting mirror 23 is adjusted. In FIG. 3, although the reflection angle of the reflecting mirror 23 is set near 90 degrees, the position of a 1st beam irradiation area | region is moved by moving the same angle from about 80 degrees to 110 degrees, and aligning the position of the condensing lens 24 at the same time. Adjustment is made. Alternatively, the position of the first beam irradiation area may also be obtained by combining one unit for fixing the relative positions of the reflector 23 and the condenser lens 24 and moving the unit horizontally along the optical axis direction of the laser beam 22. Adjustment is possible.

The laser beam 26 emitted from the CO ₂ laser 25 is reflected vertically downward by the reflector 28 via the beam expander 27. When the laser beam 26 of beam diameter 4mm passes through the beam expander 27, the beam diameter is enlarged about 4 times, and it becomes a beam of 16mm. The magnified beam passes through the diffractive optical element 29 to be shaped into an elongated beam, and forms a second beam irradiation region by the second laser beam on the glass substrate 11.

The cooling device 30 is provided behind the second beam irradiation area by the second laser beam. As the cooling device 30, a two-pipe-type cooling nozzle is used to inject water from the inner cylindrical pipe and air from the outer cylindrical pipe. The cooling medium is formed on the glass substrate 11 by spraying the mixed medium of water and air toward the glass. In front of the first laser beam, an initial crack forming apparatus 31 is provided. The initial crack formation apparatus 31 is equipped with the diamond cutter in the lower end part, and has the lifting mechanism which moves the diamond cutter up and down. By interlocking the lifting mechanism and the servo motor 33 for Y-axis drive, an initial stage crack can be formed in the edge part of the glass substrate 11.

Furthermore, in, and were using two CO ₂ laser, with only one CO ₂ laser may be performed for the beam split by the beam transmitted onto the transmission path arrangement of a beam splitter, and the second path in the present embodiment. In this case, the distribution ratio of energy by the beam splitter is such that energy of 50% or more is distributed to the first laser beam side irradiating the front side, and energy of less than 50% is distributed to the second laser beam side irradiating the rear side. Is preferred.

Fig.1 (a) is a mutual position of the irradiation position of a 1st laser beam, the irradiation position of a 2nd laser beam, and a cooling position on the glass substrate surface for demonstrating the principle of the cutting method of brittle material by this invention. A conceptual plan view showing the relationship, FIG. 1 (b) is a diagram showing a temperature profile when the heating by the first laser beam and the second laser beam in FIG. 1 (a) is superimposed on the glass substrate surface, FIG.1 (c) is a conceptual top view explaining the phenomenon by the position shift of the 1st laser beam and the 2nd laser beam in FIG. 1 (a). 2 is a conceptual perspective view of an essential part for explaining the principle of the cutting method of brittle material according to the present invention.

The basic principle of the cutting method of the brittle material according to the present invention is, as shown in Fig. 1 (a), along the cutting schedule line 12 of the glass substrate 11, from the front of the cutting to the first beam irradiation area ( 13) and 2nd beam irradiation area | region 14 and cooling point (or cooling position) 15 are arrange | positioned in order.

As shown in FIG. 3, the first beam irradiation area 13 reflects the laser beam 22 from the CO ₂ laser 21 in a predetermined direction by the reflector 23, and is predetermined through the condenser lens 24. It is produced by adjusting to the beam diameter of, the cross-sectional shape is circular or elliptical, collectively referred to as generally circular throughout the specification and claims. The 1st beam irradiation area | region 13 is a laser beam of the intensity | strength so that only heating may generate | occur | produce locally in the glass substrate 11 and neither melting nor a crack will arise.

The 2nd beam irradiation area | region 14 is located behind the 1st beam irradiation area | region 13, The cross-sectional shape is shape | shape-shaped in elongate shape in the direction along the dividing plan line 12 of the glass substrate 11. That is, the length of the 2nd beam irradiation area | region 14 in the width direction whose length (a) of the direction along the dividing line 12 of the glass substrate 11 along the cut line 12 of the glass substrate 11 is a right angle direction. It is a non-circular beam longer than (b). It is preferable that ratio (a / b) with respect to the width | variety (b) of the length (a) of the longitudinal direction along the cutting schedule line 12 in an elongate non-circular beam with respect to the width (b) of about 26-30 is preferable.

Such an elongate non-circular beam expands the laser beam 26 from the CO ₂ laser 25 to the diameter of a predetermined magnification with the beam expander 27, and reflects it in the predetermined direction by the reflector 28, and then diffracts it. It is produced by shaping through a beam shaping means 29, such as an optical element or planar cylindrical lens. The 2nd beam irradiation area | region 14 is also a laser beam of the intensity | strength so that only heating may generate | occur | produce locally in the glass substrate 11, and melt | fusion or a crack does not generate | occur | produce.

Next, the operation will be described. In FIG. 2, the initial stage crack 16 is first formed by the initial stage crack forming apparatus 31 in the edge part of the cut | disconnection planar line 12 of the glass substrate 11. In FIG. This initial crack 16 is the starting position of the cutting edge of the glass substrate 11. Next, the glass substrate 11 mounted on the table 32 is moved to the Y direction by the servo motor 33 for Y-axis drive, and the start position of the cut | disconnected scheduled line 12 of the glass substrate 11 is carried out. Heating of glass is started from the direction of the initial stage crack 16 corresponded to. As shown in FIG. 1A, the column directions of the first beam irradiation region 13, the second beam irradiation region 14, and the cooling point 15 are arranged side by side on a straight line. It is movable in accordance with the direction of 12). At this time, as shown in FIG. 1C, due to lack of adjustment, the center position of the first beam irradiation region 13 and the second beam irradiation region 14 with respect to the cutoff schedule line 12 of the glass substrate 11. If the center position of is misaligned by a small value Δd, the surface quality of the divided glass cross section deteriorates, so that the center position of the first beam irradiation region 13 and the center position of the second beam irradiation region 14 are divided by the cut line ( It is necessary to adjust the position precisely so as not to deviate with respect to 12).

Next, from the state where the position of the initial crack 16 formed in the glass substrate 11 and the column direction of the 1st beam irradiation area | region 13, the 2nd beam irradiation area | region 14, and the cooling point 15 corresponded, When the coolant is injected from the cooling device 30 while irradiating the laser beam 1 and the second laser beam, the glass substrate 11 placed on the table 32 is moved in the Y direction by the servo motor 33. Of the first beam irradiation region 13, the second beam irradiation region 14, and the cooling point 15 by the refrigerant along the split schedule line 12 of the glass substrate 11 placed on the table 32. Heat moves relatively to initiate cleavage.

The basic principle of the cutting method of the brittle material according to the present invention is, as shown in Fig. 1 (a), along the cutting schedule line 12 of the glass substrate 11, from the front of the cutting to the first beam irradiation area ( 13), the 2nd beam irradiation area | region 14 and the cooling point 15 are arrange | positioned in order. The 1st beam irradiation area | region 13 preheats the foremost part of the cutting edge of the glass substrate 11, and heats the position by the following 2nd beam irradiation area | region 14, and makes it into the state just before cutting | disconnection start. FIG.1 (b) is the temperature profile in the glass substrate 11 surface at this time. That is, the temperature profile 141 by the 2nd beam irradiation area | region 14 overlaps with the temperature profile 131 by the 1st beam irradiation area | region 13, and the 2nd beam in the surface of the glass substrate 11 The position to which the irradiation area 14 was irradiated is heated to the high temperature just before cut start. The heat by this heating conducts heat in the thickness direction of the glass substrate 11.

When a coolant is injected from the cooling device 30 to the glass substrate 11 in a preheated state in the first circular beam irradiation region 13 which is approximately circular and heated in the second elongated beam irradiation region 14, the refrigerant is shown in FIG. 2. As shown in the figure, the crack enlarged from the initial crack 16 immediately below the cooling point proceeds in the depth direction of the glass substrate 11, and the crack is formed of the glass substrate 11, the first beam irradiation region 13, and the first crack. The two-beam irradiation region 14 and the row of the cooling points 15 progress along the cutting schedule line 12 of the glass substrate 11 in accordance with the relative movement in the Y direction. As a result, the cut surface 17 is generated over the entire plate thickness of the glass substrate 11.

This state will be described in more detail with reference to FIG. 4. 4 is a cross-sectional conceptual view of a main part for explaining in detail the principle of the method of cutting brittle materials according to the present invention in FIG. 2, (a) is a cross-sectional conceptual view, and (b) is A- in FIG. A 'cross section.

When the rows of the first beam irradiation region 13, the second beam irradiation region 14, and the cooling point 15 are scanned in the Y direction with respect to the glass substrate 11, the glass substrate 11 is first made of first. It heats in the 1 beam irradiation area | region 13, and the heat by the heating conducts heat to the back surface direction of the glass substrate 11 according to the scan to a Y direction, and the heating area | region 130 is formed in the glass substrate 11. Next, the glass substrate 11 is heated in the 2nd beam irradiation area | region 14, and the heat by the heat conducts heat to the back surface direction of the glass substrate 11 according to the scan to a Y direction, and the glass substrate 11 The heating region 140 is formed within. The cooling by the cooling point 15 in the rear part of the 2nd beam irradiation area | region 14 similarly heat-conducts to the back surface direction of the glass substrate 11 according to the scan to the Y direction of the glass substrate 11, A cooling region 150 is formed in 11.

As a result, the heat distribution of the glass substrate 11 directly under the cooling point 15 is as shown in FIG. 4 (b), and the glass substrate 11 is formed by the first beam irradiation region 13. Cooling by the cooling point 15 acts on the heating region 130 heated by the vicinity of the back surface and the heating region 140 heated by the second beam irradiation region 14 subsequent thereto, and is directly below the cooling point. The crack progresses in the depth direction of the glass substrate 11, reaches the rear surface of the glass substrate 11, and cuts it over the entire plate thickness direction. This phenomenon advances along the cutting schedule line 12 of the glass substrate 11 along with the scanning of the glass substrate 11 in the Y direction, and reaches the rear surface of the glass substrate 11 along the cutting schedule line 12. One cut is in progress.

8 is a graph showing temperature distribution in the thickness direction of glass. In the above description using FIG. 4 (a), the state of heat propagation in the thickness direction of the glass was described as being simply propagated from the surface of the glass to the back surface at a constant speed in a linearly functional manner. . However, since the propagation of heat inside the glass should be actually calculated based on the heat diffusion equation, it illustrates one result obtained by applying the equation to non-alkali glass.

The graph of FIG. 8 calculates how the temperature distribution in the thickness direction changes when assuming that a uniform heat distribution of 20 J / cm 2 is applied to one side of a non-alkali glass having a thickness of 0.7 mm and an infinite size. The result is a graph. The horizontal axis of the graph represents the depth of heat propagation, that is, the thickness of the glass (mm), and the vertical axis represents the temperature rise, that is, how much the temperature rises from the initial state of the glass. The reason why the plurality of curves are described in the graph is because the state of elapsed time after the initial heating is changed as a parameter to display the plurality of graphs overlaid.

Only by initially applying a heat amount of 20 J / cm 2 to one side of the glass, the heated glass surface instantly exceeds 400 ° C., and then the surface temperature of the glass suddenly decreases. At the same time as the temperature of the heating surface decreases, heat from the surface is transmitted to the back surface side without heating, so that the temperature rises, and the temperature is slightly higher than 100 ° C. The elapsed time parameters are calculated by sampling 10 pieces of time up to 1.0 second, and from the one with the shortest elapsed time, T1 = 30 msec, T2 = 40 msec, T3 = 50 msec, T4 = 75 msec, T5 = 100 msec, and T6 = 200 msec, T7 = 300 msec, T8 = 400 msec, T9 = 700 msec, and T10 = 1000 msec. It can be seen from this graph that, after T1, that is, 30 msec, there is a large temperature difference of 400 ° C on the surface and the backside of the 0.7 mm thick glass, but after T6, that is, 200 msec, the temperature difference is relaxed to about 50 ° C. In addition, after T7 or 300 msec, it becomes about 30 degreeC of temperature differences, and it can be said that the surface and the back surface are about the same temperature.

In this embodiment using a CO ₂ laser, the heat energy supplied by the first laser beam irradiated to the front of the advancing direction propagates to the back surface of the glass, thereby being utilized as an energy source for full body cutting. There is this. In order to perform such full-body cutting, it is necessary for the heat energy absorbed at the glass surface to thermally spread to some extent in the glass. Then, one important item is how much distance L is to be set between the cooling point and the irradiation area of the first laser beam along the cutting schedule line. Here, if the moving speed of glass is set to V and the moving time taken for the glass surface irradiated by the first laser beam to move below the cooling point is τ, the relationship of L = V · τ is established. As mentioned above, in order for the temperature of the glass surface and the back surface to become substantially the same, time of 200 to 300 msec is required. That is, if the moving speed of glass is 180 mm / s, the distance of 36 mm in the elapsed time of 200 msec and 54 mm in the elapsed time of 300 msec will be moved. Therefore, the distance L between the cooling point and the irradiation area of the first laser beam needs to set a distance of at least 36 mm, preferably 54 mm or more.

Thus, how much distance L should be set between a cooling point and the irradiation area of a 1st laser beam depends on the movement speed of glass and the thickness of glass. More specifically, it also relates to the physical constants related to the thermal diffusion rate inside the glass, that is, the thermal conductivity, specific heat, and density of the glass. Moreover, it also relates to the boundary conditions in the back surface of glass. In other words, it is also affected whether the back surface of the glass is fixed by means of close contact with the metal table or by means of floating in air.

In the present embodiment, since the crack enlarged from the initial crack 16 directly under the cooling point proceeds in the depth direction of the glass substrate 11 essentially, an imbalance is caused in the tensile stress acting on the creepage direction of the glass substrate 11. It does not occur, and the cut section 17 does not curve with respect to the cut schedule line 12. In addition, there is no micro crack in the cut section 17 formed by advancing the crack only by the thermal stress by the laser, and the mechanical strength of the glass substrate 11 after the splitting is also high.

At the end portion on the cut scheduled line 12 opposite to the initial crack 16, the tensile stress sufficient to cut the glass to the full body is lost, so when the cut surface of the full body approaches the end on the opposite side, the cut portion 17 ) Stops. At this time, as shown in FIG. 5, the area | region 18 in which the cut surface 17 does not generate | occur | produce remains in the edge part of the glass substrate 15. FIG. The cut section 17 is not formed in this region 18, but a scribe groove 19 is formed on the surface. Therefore, if necessary, the glass can be completely broken down by using simple brake means. In this case, since the glass substrate 11 is already full-body cut | disconnected over almost the entire length of a process length, generation | occurrence | production of the collit by a brake process can be suppressed significantly.

Example 1

In the glass dividing apparatus shown in FIG. 3, in the first beam irradiation region 13, the laser beam 22 from the CO ₂ laser 21 having an output of 165 W is reflected vertically downward by the reflecting mirror 23 to collect light. The light was collected through the lens 24. As a result, on the glass substrate 11, the circular beam irradiation area | region near a Gaussian distribution of beam diameter 15mm is formed. The second beam irradiation region 14 in, and using the output 98W, a beam diameter 4㎜ laser beam 26 from the CO ₂ laser (25). The laser beam 26 extends to a beam diameter of 16 mm by way of the beam expander 27, and is further transmitted vertically downward by the reflector 28. When a laser beam having a beam diameter of 16 mm passes through the diffractive optical element 29, an elongated beam having a length a of 26 mm and a width b of 1 mm is formed on the glass substrate 11.

In this manner, 165 W is applied to the first beam irradiation region 13 by the first laser beam, and 98 W is applied to the second beam irradiation region 14 by the second laser beam. That is, even if the loss of beam transmission is considered on the glass substrate 11, the thermal energy provided to the 1st beam irradiation area | region 13 is set larger than the thermal energy provided to the 2nd beam irradiation area | region 14. FIG.

Moreover, regarding the laser power density, the laser power density of the 1st laser irradiation area | region 13 is 0.93W / mm <2>, and the laser power density of the 2nd laser irradiation area | region 13 is 3.77W / mm <2>. That is, the laser power density of the first beam irradiation area 13 is set lower than the laser power density of the second laser irradiation area 13.

As the glass substrate 11, non-alkali glass of thickness 0.7mm and full length 580mm was used. As a cooling device, water was blown from an inner cylinder pipe and air was blown from an outer cylinder pipe using a two-pipe cooling nozzle. The distance between the rear end of the second beam irradiation region 14 and the cooling point 15 was set to 5 mm. The glass substrate 11 and the first beam irradiation region 13, the second beam irradiation region 14, and the relative movement distance of the heat of the cooling point 15, that is, the cutting process speed of the glass to 180mm / s Done. As a result, full-body cutting became possible over the length of 540 mm except about 40 mm of the terminal parts of the glass substrate 11. At this time, the linearity accuracy of the cut was within ± 250 μm. On the same conditions, even when cutting the position of 290 mm wide and 580 mm copper glass 15 mm away from the end face, the linearity accuracy was ± 250 µm, and there was no influence of curvature due to the so-called size effect.

The beam diameter of the first beam irradiation region 13 was changed from 10 mm to 16 mm, and the distance between the rear end of the second beam irradiation region 14 and the cooling point 15 was changed to 3 to 7 mm. Was obtained. In addition, the scanning speed raises the power of the CO ₂ lasers 21 and 25, and at the same time, the distance between the cooling point and the second beam irradiation region 14, and the second beam irradiation region 14 and the first beam irradiation region. By increasing the distance of (13), it was confirmed that the speed can be further increased. Moreover, even if the ratio (a / b) with respect to the length (a) and width (b) of the elongate non-circular 2nd beam irradiation area | region 14 was changed in the range of 26-30, the same splitting result was obtained. .

Example 2

FIG. 6 is a conceptual diagram showing a cutting device for the brittle material in Example 2. FIG. 7 shows a beam profile for heating. This beam profile is obtained by shielding the center part of the output beam from the condensing lens 24 of the 1st beam irradiation area | region 13 with the beam shield 35 of predetermined width in the glass dividing apparatus shown in FIG. Beam profile. For example, a metal rod having a diameter of 2 mm is disposed on the beam path through which the beam is transmitted. Since a part of the first laser beam is then shielded by the metal rod, the part of the so-called shadow is projected on the glass substrate, so that part is not heated. In Example 2, the shape of the 1st beam irradiation area 130 becomes a shape which divided the substantially circular center part into predetermined width w as FIG.7 (a). If the blocking portion 133 of the predetermined width w in the first beam irradiation region 130 is set to be slightly larger than the beam width e of the second beam irradiation region 14, the surface of the glass The portion where the heating region by the first beam irradiation region 130 and the heating region by the second laser beam overlap does not exist. Therefore, the temperature profile on the glass substrate surface by the 1st beam irradiation area | region 13 and the 2nd beam irradiation area | region 14 becomes like FIG.7 (b), and is a heat used for heating a cut | disconnection scheduled line image. The energy 141 and the heat energy 131 which heats the parts of both sides which have the split schedule line between them can be distinguished.

The cutting process in the second embodiment was essentially the same as in the first embodiment, and full body cutting was possible in the same manner as in the first embodiment. In addition, in Example 1, the heat energy for heating the split schedule line image is the heat energy in which the 1st laser beam irradiates the split schedule line image, and the 2nd beam irradiation area | region 14 overlapped. Supplied as. However, according to the second embodiment, heat energy for heating the cut-off scheduled line is supplied only to the first laser beam 14, so that the setting of the laser power to be irradiated becomes easy. As a result, there is an advantage that the linearity accuracy is improved, and full-body cutting is possible with precision within ± 100 µm over the entire length of 540 mm.

FIG. 12 summarizes the results of whether full-body cutting is achieved in the case of the glass cutting experiment in the configuration of the processing apparatus shown in FIG. 3. As a beam profile, the substantially circular 1st beam irradiation method shown to Fig.1 (a) was used. The used glass is non-alkali glass of thickness 0.7mmt. As a procedure of a process, the method of dividing the glass of width 550mm of an external shape and the length of 290mm of processing directions from one end surface by the regular space | interval (30mm) in a long rectangular shape was employ | adopted.

As can be seen from the description in the table of FIG. 12, when the laser power P1 irradiated to the first beam irradiation region is set larger than the laser power P2 irradiated to the second beam irradiation region, the full body is provided. Cutting is achieved in good condition (see processing conditions # 1, # 5, # 6, # 9, # 10, # 11). In the case where the laser power P1 is set to be substantially the same as the laser power P2, the length of the remainder of the glass end portion tends to be somewhat longer (see processing conditions # 2 and # 7). On the other hand, when the laser power P1 is smaller than the laser power P2, full body cutting is not achieved, the remaining length of the glass end is long, or the surface quality of the cutting surface is deteriorated. Poor machining results were obtained (see machining conditions # 3, # 4, # 8). In particular, in order to achieve a fast processing speed (for example, 200 mm / s or more), it has proved effective to set the laser power P1 much larger than the laser power P2 (processing conditions # 9, # 10). , # 11). In addition, when the processing speed V was 230 mm / s, the distance L of a cooling position and a 1st beam irradiation area was set to 95 mm. Substituting these numerical values into the relational formula of L = V · τ yields a value of τ = 413 (msec). This value tau represents the elapsed time taken for the glass surface heated by the irradiation of the first laser beam to move to the cooling position. On the other hand, in the graph of the simulation result shown in FIG. 8 mentioned above, the result of the consideration that the graph becomes flat state and the elapsed time of 200 msec or 300 msec or more is required for time to reach thermal equilibrium is obtained. Since the value of this elapsed time (tau) = 413 (msec) is a value of 300 msec or more, it does not contradict with the examination result based on FIG. That is, when the processing speed V becomes faster, the distance L of a cooling position and a 1st beam irradiation area | region turned out to set the distance L longer accordingly.

Industrial availability

The glass used for flat panel displays, such as liquid crystal displays and plasma displays, is currently cut with a diamond cutter, and shows problems such as the necessity of a cleaning process after cutting due to the generation of cullet and a decrease in strength due to the presence of microcracks. have. The dividing apparatus and the cutting method of the brittle material according to the present invention can be used for cutting of various brittle materials such as glass, quartz, ceramics, semiconductors, etc., for use in flat panel displays such as liquid crystal displays and plasma displays. When the apparatus for dividing and cutting the brittle material according to the present invention is introduced into a manufacturing process such as a flat panel display, a great effect can be expected in improvement of processing speed, processing quality, economy, etc., overcoming weaknesses of the prior art, and the like.

11: glass substrate 12: cutout line
13: first laser beam 14: second laser beam
15 cooling point or cooling position 16 initial crack
17: cut section 18: area where the cut section does not occur
19: scribe groove 21: CO ₂ laser
22 laser beam 23 reflector
24: condenser lens 25: CO ₂ laser
26: laser beam 27: beam expander
28 reflector 29 beam shaping means
31 cooling device 31 initial crack forming device
32: Table 33: X-Y drive unit
131: temperature profile by the first laser beam
133: shielding part
141: temperature profile by the second laser beam

Claims (17)

By cutting the brittle material along the cut schedule line from the initial crack side formed on the cut schedule line, and moving the position along the cut schedule line relatively to the cut schedule line assumed for the brittle material. As a dividing device of brittle material for dividing brittle material,
Laser beam irradiation means for irradiating a laser beam to the brittle material along the cut schedule line to generate a heated portion;
And cooling means for locally cooling the brittle material at a position behind the heating portion with respect to the direction of movement along the cut line.
The laser beam irradiation means,
A first beam irradiator for forming a first laser beam irradiated area located in the heating direction, in front of the moving direction;
And a second beam irradiation part in the heating portion, forming a second laser beam irradiation area having an elongated shape along the cut line in the rear of the moving direction of the first laser beam irradiation area. Brittle material splitting device. The method according to claim 1,
The laser power provided to the 1st laser beam irradiation area formed by the said 1st beam irradiation part is larger than the laser power provided to the 2nd laser beam irradiation area formed by the said 2nd beam irradiation part, The brittle material characterized by the above-mentioned. Splitting device. The method according to claim 1 or 2,
The laser power density of the first laser beam irradiation area formed by the first beam irradiation part is lower than the laser power density of the second laser beam irradiation area formed by the second beam irradiation part. Device. The method according to claim 1,
The position of the first laser beam irradiation region formed by the first beam irradiation section is relative to the cooling position formed by locally cooling the position away from the rear end of the second laser beam irradiation region by the cooling means. A device for dividing brittle material, characterized in that the distance in the direction along the cut schedule line is variable. The method of claim 4,
A distance between the position of the first laser beam irradiation area and the cooling position is set based on at least one of a cutting speed and a thickness of the brittle material. The method according to claim 1,
And the first laser beam irradiation area is substantially circular in shape. The method according to claim 1,
And the first laser beam irradiation area has a shape in which a central portion having a substantially circular shape is divided into a predetermined width. The method according to claim 7,
The first laser beam forming the first laser beam irradiation region is generated by arranging a shield having a predetermined width in the center of the optical path of the laser light from the first beam irradiation unit. The method according to claim 1,
The second laser beam forming the second laser beam irradiation area is generated by passing the laser light from the laser light source of the second beam irradiation part through a diffractive optical element or a flat convex cylindrical lens and shaping it. Split device for brittle materials. The method according to claim 1,
And an initial crack forming means for forming an initial crack at an end portion of the breaking schedule line of the brittle material, and moving the first beam irradiation section and the second beam irradiation section from the position of the initial crack along the cutting schedule line. Split device of brittle material. The method according to claim 1,
The laser beam irradiating means includes a beam splitter for distributing 50% or more of the laser power to the first beam irradiator and distributing less than 50% of the laser power to the second beam irradiator. Splitting device. As a cutting method of a brittle material which cuts the brittle material by heating along the cut line of brittle material, and moving the brittle material and the said heating position relatively along the cut line.
An initial crack is formed at an end of the brittle material on the cut schedule line, and heating of the brittle material is performed by the first laser beam and the second laser beam using the initial crack as a starting point. A beam located in a forward direction of a moving direction along the splitting line with respect to the second laser beam, and the second laser beam is a thin elongated beam along the splitting schedule line, A method of cutting brittle material, characterized in that for cooling locally a position separated from the rear end by a predetermined position. The method of claim 12,
The laser power applied to the first laser beam irradiation area formed by the first laser beam is greater than the laser power applied to the second laser beam irradiation area formed by the second laser beam. Cutting method of brittle material. The method according to claim 12 or 13,
The laser power density of the first laser beam irradiation area formed by the first laser beam is lower than the laser power density of the second laser beam irradiation area formed by the second laser beam. Part way. The method of claim 12,
The position of the 1st laser beam irradiation area | region formed by the said 1st laser beam is based on the said cutting schedule line with respect to the cooling position formed by locally cooling the position away from the rear end of the said 2nd laser beam. The cutting method of the brittle material, characterized in that the distance in the direction is variable. The method according to claim 15,
The distance between the position of the first laser beam irradiation area and the cooling position is set based on at least one of the cutting speed and the thickness of the brittle material. The method of claim 12,
An initial crack is formed at an end portion of the cut schedule line of the brittle material, and the first laser beam and the second laser beam are moved from the position of the initial crack along the cut schedule line.

Images