JP2009107301A - Full body cutting method for brittle material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a full body cutting method attaining high-speed thermal stress cutting and preventing a cut part from being curved with respect to a cutting predetermined line in cutting. <P>SOLUTION: Full body cutting is carried out by applying bending stress 14, 15 to both sides along the cutting predetermined line 12 of a glass substrate 11 and irradiating and scanning laser beams 17 serving as a local heat source along the cutting predetermined line 12 to which the bending stress 14, 15 is applied. An initial crack 13 is formed at one end of the cutting predetermined line 12, and cutting is advanced along the cutting predetermined line 12 from the initial crack 13. The cutting speed is controlled by the scanning speed of the laser beams 17. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a full-body cleaving method of a brittle material, in particular, a full-cut glass for a flat panel display. Hereinafter, glass will be described as an example of the brittle material, but the present invention can be applied to brittle materials such as quartz, ceramics, and semiconductors in addition to glass.

Recently, in the glass cleaving, a thermal stress cleaving method by laser light irradiation (hereinafter abbreviated as a laser cleaving method) has been used in place of the diamond chip mechanical method that has been used for the past century.

  According to the laser cleaving method, defects inherent in the mechanical method, that is, a decrease in glass strength due to the occurrence of microcracks, contamination due to the occurrence of cullet during cleaving, the presence of a lower limit value of the applied plate thickness, etc. can be eliminated.

According to this laser cleaving method, polishing and cleaning, which are subsequent steps of mechanical cleaving, are not required, a mirror surface having a surface roughness of 1 μm or less is obtained, and the product external dimension accuracy is ± 25 μm or more. Furthermore, it can be used for glass plates with a thickness of up to 0.05 mm, and can be used for future glass for liquid crystal displays.

  The principle of the laser cleaving method is as follows. Only glass is heated locally, and the laser beam is irradiated to such an extent that vaporization, melting and cracks do not occur. At this time, the glass heating portion tries to expand thermally, but cannot sufficiently expand due to the reaction from the surrounding glass, and compressive stress is generated in the heating region. Even in the peripheral non-heated region, the peripheral portion is further distorted by the expansion from the heating portion, and as a result, compressive stress is generated. These compressive stresses are radial. By the way, when the object has a compressive stress, a tensile stress related to the Poisson's ratio is generated in the orthogonal direction. Here, the direction is a tangential direction. This is shown in FIG.

FIG. 1 shows changes in the radial stress component σ _x and the tangential stress component σ _y when there is a temperature increase in the Gaussian distribution centered at the origin. The radial stress component σ _x is a compressive stress (negative value in FIG. 1) from beginning to end, while the tangential stress component σ _y is a compressive stress at the heating center (distance r = 0), but tensile stress when it is away from the heating center. (Positive value in FIG. 1).

Among these stresses, the tensile stress is related to the cleaving. When the tensile stress exceeds the fracture toughness value that is a material specific value, fracture occurs everywhere and is uncontrollable. In the case of the laser cleaving method, the tensile stress is selected below this fracture toughness value, so no fracture occurs.

However, when there is a crack at the position where the tensile stress is present, stress expansion occurs at the tip of the crack, and when the expanded stress exceeds the fracture toughness value of the material, the crack expands. That is, controlled cleaving occurs. Therefore, the crack can be extended by scanning the laser irradiation point. In this laser cleaving method, since the fractured surface is similar to the cleavage plane of the crystal, there is no generation of microcracks or cullet, the disadvantages of the mechanical method described above can be eliminated, and excellent properties as a glass processing method It is what you have.

This glass laser cleaving method was first developed by Kondratenko, and the Japanese Patent of Patent Document 1 was established.
Japanese Patent No. 3027768 FIG. 2A shows the principle of the laser cleaving method according to Patent Document 1. FIG. As the laser light, CO2 laser light is used, and 99% of the energy in the beam spot 1 of the CO2 laser light is absorbed in the glass surface layer having a depth of 3.7 μm on the glass plate 2, over the entire thickness of the glass plate 2. Not transparent. This is due to the extremely large absorption coefficient of glass at the CO2 laser wavelength. The depth of the cleaving by the laser (hereinafter referred to as “scribe”) is usually about 100 μm even if it is assisted by the heat conduction 4 in the glass plate 2. However, the glass plate 2 is highly brittle, and it is easy to mechanically cleave it by applying stress according to the scribe line. The process of cleaving by applying the bending stress is referred to as “break”. The laser beam is scanned in the cleaving direction 3. Although this method has advantages compared to the conventional mechanical method, its practicality is limited to the necessity of a break, and its diffusion has not necessarily been perfect.

  On the other hand, when the laser beam 5 is transmitted through the glass plate 2 as shown in FIG. 2B and a part of the glass plate 2 is absorbed, the transmitted light 6 reaches the entire thickness of the glass plate 2. On the other hand, since the cleaving is generated, the glass plate 2 can be cleaved only by this process, and the break becomes unnecessary. This cleaving is referred to as full body cleaving (or full cutting) by a laser.

By adopting full cut, in addition to the technical features of the laser cleaving method described above, a break is not required, free curve cleaving is possible, and selective cleaving from one direction of laminated glass is possible. A merit peculiar to cutting has arisen, and it has become possible to realize incredible improvements in the flat panel manufacturing process. Remi Co., Ltd. has proposed Patent Documents 2 to 6 for this full cut technology.
JP 2006-256944 A JP 2006-347793 A JP 2007-55072 A JP 2007-76077 A Japanese Patent Application No. 2007-261885

Since the cleaving according to Patent Document 1 is not a full cut, a break process is required and the practicality is limited as described above. Full cutting by laser proposed in Patent Documents 2 to 6 is an excellent technique, but if the cleaving position is separated from the end of the workpiece due to the so-called size effect, the cleaving speed is remarkably reduced or close to the end. There is a disadvantage that the split section is bent. The disadvantage due to the size effect will be described with reference to FIG.

First, the low speed property which is the first drawback of the brittle material full cut will be described. In FIG. 3 (a), consider a case where breaking the glass plate 2 in a large state width W ₁ and W _2. When the laser beam 5 is scanned along the cleaving line 7 in the cleaving direction 3, a tensile tension is generated on the glass plate 2 by the above-described principle due to heating by laser beam irradiation, and the glass plate 2 follows the scanning locus of the laser beam 5. It will be divided. In FIG. 3A, this deformation is exaggerated, and the actual movement of the glass after the cleaving is about several microns.

At this time, if the widths W ₁ and W ₂ of the glass plate 2 on both sides of the breaking line 7 are large, the scanning speed of the laser beam 5 is significantly reduced. First, the tensile stresses F ₀ and F ₁ necessary for cleaving the glass plate 2 must overcome the resistance to deformation described above. This resistance acts on the area of the glass plate 2 and increases remarkably when the widths W ₁ and W _{2 of} the glass plate ₂ are large. Since the cleaving of the glass plate 2 must be performed against a large resistance, it is necessary to reduce the scanning speed of the laser beam 5 and relatively increase the amount of heating by the laser beam 5.

As a result, the scanning speed of the laser beam 5 has to be low, so the cleaving speed is naturally limited. This tendency becomes more prominent as the distance between the position of the breaking line 7 and the end of the glass plate 2 is larger, that is, as the widths W ₁ and W _{2 of the} broken glass plate 2 in FIG. For example, when the breaking line 7 is at a distance of 500 mm from the end of the glass plate 2, full cutting cannot be performed unless the scanning speed of the laser beam 5 is set to a remarkably low speed of about 10 mm / s.

Next, the fact that the fractured surface of the brittle material, which is another drawback of the full cut of the brittle material, is curved with respect to the planned fracture position will be described. As described with reference to FIG. 3A, the cleaving when the laser beam 5 is scanned in the cleaving direction 3 along the cleaving line 7 is performed in the creeping direction by the tensile stresses F ₀ and F ₁ acting on the glass plate 2. . At that time, when there is an imbalance in the above-described resistance force on both sides, a force is exerted on the split section to bend with respect to the planned cutting line. This is shown in FIG. FIG. 3B shows that when the width W ₃ is small, the resistance on the side of the width W ₃ is small, so that the curve is greatly curved, and the split section after cleaving is curved in a bow shape. This tendency is remarkable when the width W ₁ and W ₃ of the glass plate 2 after cleaving imbalance, especially one having a width W ₃ is particularly small. Also in this case, as described above, the deformation of the workpiece is shown exaggerated more than the actual one of several microns.

The present invention solves these problems of the prior art, and has two drawbacks resulting from the size effect in the full-cut technique by laser, that is, the cleaving speed is low and the cleaving portion is curved with respect to the cleaving line. While eliminating this, and realizing the high quality of thermal stress cleaving by laser, the cleaving speed can be greatly increased, and the cleaved section can be cleaved in a straight line without being bent with respect to the cleaved planned line. The object is to provide a full body cleaving method.

Both the low speed and the curve characteristic of the full cut are caused by the fact that the deformation for realizing the full cut is realized as the movement in the work plate surface as shown in FIGS. 3 (a) and 3 (b). ing. The low speed property is attributed to the fact that the resistance force increases as the width on both sides of the cleaving position increases, and the bending characteristic is attributed to the fact that the resistance force on both sides also becomes unbalanced when the widths on both sides are unbalanced. Such a situation can be eliminated by causing the deformation for realizing the full cut to be performed not in the plane but in the direction perpendicular to the plane.

In order to achieve the above object, the present invention applies a deformation stress acting in the thickness direction along a planned fracture line of a brittle material, and a local heat source along the planned fracture line to which this deformation stress is applied. To cut the full body. Specifically, the following configuration is provided.

The full body cleaving method of the brittle material of the present invention according to the first configuration applies a deformation stress acting in the thickness direction of the brittle material along the planned fracture line of the brittle material, and locally along the planned fracture line. The brittle material is cleaved by scanning a heat source.
The full body cleaving method of the brittle material of the present invention according to the second configuration is the full body cleaving method of the brittle material according to the first configuration, in which the deformation stress acting in the thickness direction of the brittle material causes the brittle material to move in the thickness direction. It is characterized by a bending stress that bends in a straight line.
The full body cleaving method for a brittle material of the present invention according to the third configuration is characterized in that the deformation stress acting in the thickness direction of the brittle material is a shear stress in the full body cleaving method for the brittle material according to the first configuration. It is what.
A full body cleaving method for a brittle material according to a fourth aspect of the present invention is the full body cleaving method for a brittle material according to any one of the first to third configurations, wherein an initial crack is formed at one end of the planned fracture line of the brittle material. It is characterized by forming.
The full body cleaving method of the brittle material of the present invention according to the fifth configuration is the full body cleaving method of the brittle material according to any one of the first to fourth configurations, in which the scanning speed of the local heat source is lowered at the initial stage of cleaving, The speed is then increased.
The full-body cleaving method of the laminated glass of the present invention according to the sixth configuration selectively forms an initial crack that sets a starting point of cleaving only in the glass to be cleaved in the laminated glass in which a plurality of glass substrates are laminated, Applying bending stress that bends in the thickness direction along the planned cutting line in the glass to be cleaved, scans the local heat source along the planned cutting line of the glass substrate, and curves out of the laminated glass curved by the bending stress The glass substrate located on the innermost side of the surface is first cleaved, and then the glass substrate adjacent to the glass substrate located on the innermost side is cleaved.
The full body cleaving method of the brittle material of the present invention according to the seventh configuration is the same as the full body cleaving method of the brittle material according to the second configuration, at a position immediately below the planned fracture line of the brittle material on the table on which the brittle material is installed. A spacer is arranged so that the vicinity of the planned cutting line of the brittle material is curved upward.
The brittle material full body cleaving method of the present invention according to the eighth configuration is the brittle material full body cleaving method according to the second configuration, wherein the brittle material is pushed from below by a pin at a position immediately below the planned fracture line of the brittle material. The vicinity of the cleaved planned line is curved upward.
The full-body cleaving method of the brittle material of the present invention according to the ninth configuration is the position of both sides of the brittle material bent upward in the full-body cleaving method of the brittle material according to the seventh or eighth configuration. Is pressed downward.
The full-body cleaving method for a brittle material of the present invention according to a tenth configuration is characterized in that a laser beam is used as a local heat source in the full-body cleaving method for a brittle material according to any one of the first to ninth configurations. Is.
The full-body cleaving method for brittle material according to the eleventh configuration of the present invention is characterized in that, in the full-body cleaving method for brittle material according to the tenth configuration, the laser light is YAG laser light.
The full-body cleaving method for brittle material according to the twelfth aspect of the present invention is characterized in that, in the full-body cleaving method for brittle material according to the tenth structure, the laser light is CO ₂ laser light.
The full-body cleaving method of the brittle material of the present invention according to the thirteenth configuration is the same as the basic method of the laser beam oscillated by the Er: YAG laser or Ho: YAG laser as the laser beam in the full-body cleaving method of the brittle material according to the tenth configuration Or third to fifth harmonics of laser light oscillated by a laser selected from Nd: YAG laser, Yb: YAG laser, Nd: YVO ₄ laser and Nd: YLF laser It is characterized by.
According to a fourteenth configuration, the brittle material full body cleaving method of the present invention is the brittle material full body cleaving method according to any one of the first to ninth configurations, in which a rare earth element is added to the brittle material to the brittle material. The light emitted from a laser diode or a rare earth solid-state laser is used as the local heat source.
According to a fifteenth aspect of the present invention, there is provided a brittle material full-body cleaving method according to any one of the first to ninth aspects, wherein a brittle material full-body cleaving method is a local heat source from an optical parametric oscillator or a mixed crystal semiconductor laser. The emitted light is used.
The brittle material full body cleaving method of the present invention according to the sixteenth configuration is the electrode in contact with the front and back surfaces of the brittle material as a local heat source in the full body cleaving method of the brittle material according to any one of the first to ninth configurations. The dielectric loss based on the high frequency voltage applied between them is used.

According to the present invention, it is possible to significantly increase the cleaving speed as compared with the prior art while realizing the high quality of thermal stress cleaving. Further, the split section can be cut into a straight line without being bent with respect to the planned cutting line. Laser glass cleaving has many great technical advantages, but has failed to replace the mechanical method of diamond chips that has been used over the past century. The present invention changes such a situation.

According to the full-body cleaving method of the brittle material of the present invention, while realizing the high quality of thermal stress cleaving, the cleaving speed is greatly increased as compared with the prior art, and the cleaved section becomes the planned cleaving line. On the other hand, the following merits are given as the merit of the present invention by cleaving into a straight line without being curved.
(1) Full-body cleaving of brittle materials can be performed at a significantly higher speed than conventional methods.
(2) The brittle material can be cleaved in only one full cut and no break is required. In addition, post-processing such as polishing and cleaning is unnecessary.
(3) There is no generation of microcracks in the vicinity of the fractured surface, and the mechanical strength of the workpiece is high.
(4) The split section is not curved with respect to the planned cutting line, and further, there is no adhesion of cullet and it is clean.
(5) Curve cutting is possible.
(6) The cleaving position accuracy is high.
(7) The fractured surface is sufficiently perpendicular to the glass surface.
(8) The fractured surface is a mirror surface and the surface roughness is good.
(9) Selective cleaving of the laminated glass can be performed by laser beam irradiation from one direction, and operations such as inversion of the glass plate are unnecessary.
(10) The cleaving can be automated.

If the full body cleaving method of the brittle material according to the present invention having such characteristics is introduced into the flat panel display manufacturing process, the effect of improving the processing speed, processing quality, economy, etc., overcoming the weaknesses of the prior art, etc. There is something that cannot be measured.

The full-body cleaving method of a brittle material according to the first embodiment of the present invention applies a deformation stress acting in the thickness direction of the brittle material along the planned fracture line of the brittle material, and follows the planned fracture line. A brittle material is cut by scanning a local heat source. According to the present embodiment, it is possible to significantly increase the cleaving speed as compared with the prior art while realizing the high quality of thermal stress cleaving. Further, the split section can be cut into a straight line without being bent with respect to the planned cutting line.
The second embodiment of the present invention uses the bending stress as the deformation stress acting in the thickness direction of the brittle material in the full body cleaving method of the brittle material according to the first embodiment. According to the present embodiment, it is possible to significantly increase the cleaving speed as compared with the prior art while realizing the high quality of thermal stress cleaving. Further, the split section can be cut into a straight line without being bent with respect to the planned cutting line.
According to the third embodiment of the present invention, in the full body cleaving method for a brittle material according to the first embodiment, the deformation stress acting in the thickness direction of the brittle material is used as the shear stress. According to the present embodiment, it is possible to significantly increase the cleaving speed as compared with the prior art while realizing the high quality of thermal stress cleaving. Further, the split section can be cut into a straight line without being bent with respect to the planned cutting line.
According to a fourth embodiment of the present invention, in the full-body cleaving method for a brittle material according to any one of the first to third embodiments, an initial crack is formed at an end portion of a brittle material fracture line. It is. According to the present embodiment, it is possible to reduce the starting threshold for crack expansion that contributes to cleaving.
According to a fifth embodiment of the present invention, in the full-body cleaving method for a brittle material according to any one of the first to fourth embodiments, the scanning speed of the local heat source is lowered at the initial stage of cleaving and then increased. Is. According to the present embodiment, in the initial stage of cleaving, the progress of cleaving is made to follow the scanning of the local heat source, and then the cleaving speed is increased to make the cleaving progress fast and surely to be a straight line. Full body cleaving can be realized. Experiments have demonstrated that the full body breaking speed can be increased to 1000 mm / s or more, which is 10 to 100 times or more that of the prior art.
The full-body cleaving method for laminated glass according to the sixth embodiment of the present invention selectively forms an initial crack that sets the starting point of cleaving only in the glass to be cleaved in the laminated glass in which a plurality of glass substrates are laminated. First, the glass substrate on the innermost side of the curved surface of the laminated glass curved by the bending stress is applied by applying a bending stress along the planned cutting line of the glass substrate and scanning the local heat source along the planned cutting line of the glass substrate. Cleaving and then cleaving the glass substrate adjacent to the innermost glass substrate. According to the present embodiment, it is possible to cleave the laminated glass by significantly increasing the cleaving speed as compared with the prior art while realizing the high quality of thermal stress cleaving by the laser. Further, the split section can be cut into a straight line without being bent with respect to the planned cutting line.
According to a seventh embodiment of the present invention, in the full-body cleaving method for a brittle material according to the second embodiment, a spacer is disposed at a position immediately below the planned fracture line of the brittle material so that the vicinity of the planned fracture line of the brittle material is located. It is bent upward. According to the present embodiment, the application of bending stress to the brittle material can be realized by a very simple method of arranging the spacers. Further, the magnitude of the bending stress can be freely controlled by the height of the spacer.
According to an eighth embodiment of the present invention, in the full-body cleaving method for a brittle material according to the second embodiment, the position immediately below the planned cutting line of the brittle material is pushed up from below by a pin, and the vicinity of the planned cutting line is moved upward. To bend. According to the present embodiment, the application of bending stress to the brittle material can be realized by a very simple method of pushing upward from below with a pin. Further, the magnitude of the bending stress can be freely controlled by the position and quantity of the pins.
In the ninth embodiment of the present invention, in the full-body cleaving method for a brittle material according to the seventh or eighth embodiment, the positions on both sides across the curved position of the brittle material curved upward are pressed downward. Is. According to the present embodiment, a desired bending stress can be reliably applied to a position curved upward of the brittle material.
The tenth embodiment of the present invention uses a laser beam as a local heat source in the full body cleaving method of a brittle material according to any one of the first to ninth embodiments. According to the present embodiment, the size, shape, position, temperature distribution and the like of the spot of the local heat source can be precisely controlled.
The eleventh embodiment of the present invention uses a YAG laser beam as the laser beam in the full body cleaving method for a brittle material according to the tenth embodiment. According to the present embodiment, the local heat source device can be reduced in size and output, and the spot size, shape, position, temperature distribution, and the like of the local heat source can be precisely controlled.
The twelfth embodiment of the present invention uses CO ₂ laser light as the laser light in the full-body cleaving method for a brittle material according to the tenth embodiment. According to the present embodiment, the local heat source device can be reduced in size and output, and the spot size, shape, position, temperature distribution, and the like of the local heat source can be precisely controlled.
In a thirteenth embodiment of the present invention, in the full-body cleaving method for a brittle material according to the eleventh embodiment, the fundamental wave of the laser beam oscillated by an Er: YAG laser or Ho: YAG laser as the laser beam, or Nd : 3rd to 5th harmonics of laser light oscillated by a laser selected from any one of: YAG laser, Yb: YAG laser, Nd: YVO ₄ laser, and Nd: YLF laser. According to the present embodiment, since the laser beam as the local heat source is optimal for full-body cleavage, full-body cleavage can be reliably performed. In addition, the local heat source device can be downsized, and the spot size, shape, position, temperature distribution, and the like of the local heat source can be precisely controlled.
According to a fourteenth embodiment of the present invention, in the full body cleaving method for a brittle material according to any one of the first to ninth embodiments, a rare earth element is added to the brittle material and used as a local heat source for the brittle material. Light emitted from a laser diode or a rare earth solid-state laser is used. According to the present embodiment, since the combination of the brittle material and the local heat source is optimal for full body cleaving, full body cleaving can be reliably performed. In addition, the local heat source device can be downsized, and the spot size, shape, position, temperature distribution, and the like of the local heat source can be precisely controlled.
The fifteenth embodiment of the present invention uses light emitted from an optical parametric oscillator or a mixed crystal semiconductor laser as a local heat source in the full-body cleaving method for a brittle material according to any one of the first to ninth embodiments. To do. According to the present embodiment, since the local heat source is optimal for full body cleaving, full body cleaving can be reliably performed. In addition, the size, shape, position, temperature distribution and the like of the spot of the local heat source can be precisely controlled.
The brittle material full body cleaving method of the present invention according to the sixteenth configuration of the present invention is the full body cleaving method of the brittle material according to any of the first to ninth configurations, contacting the front and back surfaces of the brittle material as a local heat source. A dielectric loss based on a high frequency voltage applied between the electrodes is used. According to the present embodiment, scanning of the local heat source can be performed at high speed.

In order to apply the deformation stress acting in the thickness direction of the brittle material along the planned cutting line of the brittle material, a bending stress or a shear stress may be applied as the deformation stress. In order to apply the bending stress along the planned cutting line of the brittle material, the vicinity of the planned cutting line of the brittle material may be curved. Specifically, a spacer is placed on the table where the brittle material is placed, just below the planned cutting line of the brittle material, and the brittle material is bent upward. The brittle material can be curved upward by pushing it up, or the brittle material can be curved downward by gravity by dropping one end of the brittle material downward from the end of the table on which the brittle material is placed.

Thermal stress generation by a local heat source can be performed by laser light irradiation, dielectric heating, or other methods. As necessary conditions, high speed, a distribution that increases tensile stress, locality for realizing high position accuracy, and the like are required. For crack expansion, it is preferable to prepare an initial crack in order to lower the threshold of starting.

When laser light is used as the local heat source, it is preferable that the laser light is transmitted through the glass and absorbed to perform a full cut. As lasers for this purpose, the fundamental wave of laser light oscillated by the Er: YAG laser or Ho: YAG laser described in Patent Document 2, Nd: YAG laser, Yb: YAG laser, Nd: YVO ₄ laser, and Nd: A rare earth element is added to the brittle material described in the third to fifth harmonics of the laser light oscillated by the laser selected from any one of the YLF lasers, Patent Document 2 and Patent Document 3, and the brittle material is obtained. As the irradiation laser light, a laser diode or a rare earth solid laser, and an optical parametric oscillator or mixed crystal semiconductor laser described in Patent Document 5 are suitable. In the case where the brittle material is thin, the present invention can be realized by using a CO ₂ laser generally used for surface scribing as a local heat source and utilizing heat conduction in the thickness direction.

As another local heat source, dielectric loss based on a high-frequency voltage applied between electrodes brought into contact with the front and back surfaces of the brittle material can also be used.

The cutting speed can be controlled by the scanning speed of the local heat source. Therefore, by lowering the speed at the initial stage of the cleaving and then increasing the speed, the progress of the cleaving is made to follow the scanning of the local heat source in the initial stage of the cleaving, and then the cleaving speed is increased to 10 times that of the prior art. Full body cleaving can be performed at a high speed of 1000 mm / s or more, which is 100 times or more.

As the brittle material to be cleaved, not only a single plate of a brittle material but also a multiple brittle material such as laminated glass can be cleaved. In the case of laminated glass, an initial crack that sets the starting point of cleaving is selectively formed only in the glass to be cleaved, bending stress is applied to both sides along the cleaving line, and a local heat source is produced along the cleaving line. Of the laminated glass curved by bending stress, the glass substrate on the innermost side of the curved surface is first cleaved, and then the glass substrate adjacent to the glass substrate on the innermost side is cleaved. While realizing the high quality of thermal stress cleaving by laser, the cleaving speed can be greatly increased as compared with the prior art for cleaving.
Hereinafter, the principle and embodiments of the present invention will be described in detail with reference to the drawings. In the following description, glass will be described as an example of a brittle material.

FIG. 4 is a conceptual cross-sectional view for explaining the principle of the brittle material full body cleaving method according to the present invention. FIG. 4A is a cross-sectional view illustrating an example in which a shear stress is applied as a deformation stress acting in the thickness direction of the brittle material along the planned cutting line 12 of the brittle material.

The force F ₁ pushing up the glass substrate 11 upward on one side of the planned cutting line 12 (the left side in FIG. 4 (a)) of the glass substrate 11, a glass substrate 11 on the other side (in FIGS. 4 (a) the right) was a force F ₂ depressing downward to scan in the vertical direction to the paper surface while irradiating the laser beam as a local heat source along a preset cleaving line 12 of the glass substrate 11. Also in this case, the microscopic breaking itself of breaking the interatomic bond is realized by the tensile stress generated in the workpiece surface by the laser beam irradiation. However in practice as a macroscopic material movement, by the action of the force F ₂ pushing down force F ₁ and the lower push up the glass substrate 11 upward, will be fractured vertically as if devote paper on the glass substrate 11.

The force F ₁ that pushes up the glass substrate 11 and the force F ₂ that pushes down the glass substrate 11, that is, the shear stress, acts in the direction of the thickness t of the glass plate 11. This is a cleaving due to deformation, and the size effect caused by the cleaving due to the deformation in the conventional creeping direction described in FIG. 3 hardly occurs. Therefore, the scanning speed of the laser beam 17 can be increased and the split section is not curved. The size of the force F ₂ pushing down the glass substrate 11 is shear stress to the force F ₁ and the lower push upwards the deformation of about width 1000mm of resistant glass substrate in the case of the work plane for fracture On the other hand, when the deformation for cleaving occurs in the direction perpendicular to the surface, it occurs for a plate thickness of about 1 mm, so that an extremely small value is sufficient. Of course, a break process is unnecessary.

FIG. 4B is a cross-sectional view illustrating an example in which a bending stress is applied as a deformation stress acting in the thickness direction of the brittle material along the planned cutting line 12 of the brittle material. When a force F ₂ that pushes the glass substrate 11 upward is applied directly below the planned cutting line 12 of the glass substrate 11, the glass substrate 11 swells upward around the planned cutting line 12 and cracks downward from the upper surface of the glass substrate 11. There bending stress F ₃ is generated as helping to proceed. When scanned in the vertical direction to the paper surface while irradiating the laser beam as a local heat source along a preset cleaving line 12 of the glass substrate 11 in this state, the glass substrate 11 along the expected splitting line 12 by the action of the bending stress F ₃ It will be cleaved as if it were a rice cracker.

Again, the force F ₂ for pushing up a glass substrate 11 upward acts in the direction of the plate thickness t of the glass plate 11, cleaving of the glass substrate 11 is caused by the direction of deformation of the plate thickness t macroscopically since by bending stress F ₃ is cleaving, size effect produced by cleaving due to the deformation of the conventional creeping direction described in FIG. 3 hardly occurs. Therefore, the scanning speed of the laser beam 17 can be increased and the split section is not curved. Of course, a break process is unnecessary.
Next, examples of the present invention will be described.

FIG. 5 is a conceptual perspective view for explaining a full-body cleaving method for a brittle material in Example 1 of the present invention. A breaking line 12 is set on the glass substrate 11. An initial crack 13 for starting cleaving is formed at one end of the planned cutting line 12. The initial crack 13 can be formed by a mechanical method such as heating with a local heat source, which will be described later, or a cutter. Further, bending stresses 14 and 15 acting downward on both sides of the glass substrate 11 around the planned cutting line 12 are applied.
A laser unit 16 is disposed above the glass substrate 11, and the laser light 17 from the unit 16 is beam-shaped using an optical system 18 and irradiated onto a condensing point 19 on the surface of the glass substrate 11. This irradiation point 19 acts as a local heat source by the laser beam 17. The glass substrate 11 is placed on a table (not shown) that can move relative to the laser unit 16. By moving the laser unit 16 or the table, the irradiation point 19 of the laser light 17 is a glass substrate. 11 can be scanned. The scanning of the irradiation point 19 of the laser beam 17 is performed in the direction of arrow A along the planned cutting line 12 from the position of the initial crack 13 formed at one end of the glass substrate 11.

FIG. 6 is a cross-sectional view at the irradiation point 19 position when the laser light 17 is irradiated from the laser unit 16 to the glass substrate 11. The laser light 17 is transmitted in the glass substrate depth direction 20 at the irradiation point 19 position on the glass substrate 11, and a part of the laser light 17 is absorbed to cause heating and generation of thermal stress in the plate thickness direction. Microscopically, this tensile stress breaks interatomic bonds. Macroscopically, since the glass substrate 11 is bent by applying bending stresses 14 and 15 acting downward on both sides of the glass substrate 11 around the planned cutting line 12, the glass substrate 11 is first generated on the upper surface. The crack 21 is pulled on both sides of the crack 21, and the crack 21 instantaneously reaches the back surface of the glass substrate 11. In this state, as shown in FIG. 5, when the irradiation point 19 of the laser beam 17, that is, the local heat source is scanned in the direction of arrow A on the surface of the glass substrate 11, the glass plate 11 follows the scanning of the irradiation point 19 from the initial crack 13. It will be divided. At this time, the cleaving proceeds following the scanning of the irradiation point 19 which is a local heat source by the action of the bending stresses 14 and 15 applied to the glass substrate 11. The initial crack 13 can lower the starting threshold for the expansion of the crack 21 in the depth direction of the glass substrate 11 and the scanning direction of the irradiation point 19.

Since the cleaving follows the scanning of the irradiation point 19 which is a local heat source, the cleaving speed can be controlled by the scanning speed of the irradiation point 19 which is a local heat source. Therefore, the scanning speed of the local heat source is set low at the initial stage of cleaving, and in the initial stage of cleaving, the progress of cleaving is made to follow the scanning speed of the local heat source stably from the initial crack 13, and then the state where the cleaving has progressed to a certain extent By increasing the scanning speed of the material, the progress of the cleaving process is progressed at a high speed and stably, and while achieving the high quality of thermal stress cleaving, the cleaving speed is greatly increased as compared with the prior art and the cleaved section However, it is possible to perform full body cleaving in a straight line without bending with respect to the planned cleaving line. Here, stable cleaving means that the fractured surface has a high quality in terms of surface roughness and positional accuracy, and it has been experimentally verified that the same quality is improved when performing the above speed control. .

FIG. 7 is a conceptual cross-sectional view for explaining a full-body cleaving method for a brittle material in Example 2 of the present invention. In the second embodiment, the bending stress applied to the glass substrate 11 is generated by the spacer 31 arranged between the glass substrate 11 and the table 30. The glass substrate 11 is made of alkali-free glass having a total width of 580 mm and a plate thickness of 0.7 mm to which 3% by weight of Yb is added, and the cutting line 12 having a distance from the end of the glass substrate 11 set to a position of 10 mm. An initial crack 13 was formed at one end of the glass substrate and placed on a table 30 via a glass spacer 31 having a thickness of 5 mm and a width of 20 mm. The glass substrate 11 is bent upward at the position of the planned cutting line 12 by the glass spacer 31, whereby bending stresses 14 and 15 are applied to the glass substrate 11 along the planned cutting line 12 on both sides thereof. Positions on both sides of the curved position of the glass substrate 11 curved upward press the glass substrate 11 downward so that the glass substrate 11 does not float from the table 30. This pressing may be performed by placing weights 22 and 23 on the surface of the glass substrate 11 or sucking them from below by vacuum or electrostatic adsorption.

The glass substrate 11 to which the bending stresses 14 and 15 are applied is irradiated with a laser beam 17 (output 1 kW) having a wavelength of 976 nm from the laser unit 16 using a condensing optical system 18 at an irradiation point 19 at a planned cutting position of the glass substrate 11 ( (Rectangular of 0.5 × 2.5 mm ² ) and linearly scanned in the long side direction of the irradiation point 19. The linear scan in the long side direction of the irradiation point 19 is in the direction of arrow A along the planned cutting line 12 in FIG. The laser light energy absorbed by the glass substrate 11 was about 300 W, and 80 W, 240 W, was converted into heat. The scanning speed is set to 200 mm / s at the initial stage of the cleaving in order to follow the scanning speed of the local heat source stably from the initial crack 13, and the crushing has progressed to some extent, and the time is about 1000 mm after about 1 second has elapsed. Scanning was set to / s. This is about 10 to 100 times faster than the conventional laser full-body cleaving, and when cleaving a glass substrate for a flat panel display of about 37 to 60 inches, one side is cleaved within 1 second. We were able to. In addition, since the width of the spacer 31 is 20 mm, even if the irradiation point 19 is misaligned, it falls within the range of the width of the spacer 31, so that no problem occurs.

The straightness of the cut section is a very high straight line, and no bending or bending is observed. In the glass substrate 11 having a total width of 580 mm and a plate thickness of 0.7 mm, the distance from the end of the glass substrate 11 to the planned cutting line 12 is Even in the case of the position of 10 mm, the accuracy of the split section was as high as about ± 20 μm even in the worst case. Further, the quality of the cut section was basically the same as that of a laser full cut by the conventional method. Further, there was no generation of microcracks or cullet, and it was confirmed that this was an ideal glass processing method.

In Example 3, the bending stress applied to the glass substrate 11 was performed by pins arranged so as to extend from the table 30 toward the glass substrate 11. A plurality of pins corresponding to the length of the glass substrate 11 were arranged at intervals of 5 mm along the planned cutting line of the glass substrate 11 at intervals of 5 mm. With the plurality of pins, the glass substrate 11 was bent upward by pushing up the position immediately below the planned cutting line from below. Electrostatic chucking devices were provided on both sides of the plurality of pins, and the glass substrate 11 was pressed downward by electrostatically chucking the positions on both sides of the curved position of the glass substrate 11 curved upward. Examples of such electrostatic adsorption devices are described in, for example, Japanese Patent Application Laid-Open Nos. 2006-156550 and 2006-147926. Since other configurations and operations are the same as those in the second embodiment, the description thereof is omitted.

Also in the cleaving method according to this example, as in Example 2, the straightness of the fractured section was a very high straight line, and no bending or bending was observed. Further, the quality of the cut section was basically the same as that of a laser full cut by the conventional method. Moreover, there was no generation of microcracks or cullet. In addition, the application of bending stress to the brittle material can be realized by a very simple method of pushing upward from below by the pins, and the magnitude of the bending stress can be freely controlled by the position and quantity of the pins.

In Example 4, the bending stress applied to the glass substrate 11 is an example in which one end of the glass substrate 11 is suspended downward from the end of the table on which the glass substrate 11 is installed, and the glass substrate 11 is bent downward by gravity. is there. In this configuration, for example, in the configuration shown in FIG. 6 of Japanese Patent Application Laid-Open No. 2006-137268, the glass plate is applied as a downward applied stress 13 to be applied to the portion of the glass plate protruding from the end of the material support base 15. If the weight applied is applied to the portion of the glass plate that is supported by the end of the material support base 15 by the downward stress due to the weight of the glass plate, the weight applied to the glass plate is reduced. Good. Since other configurations and operations are the same as those in the second embodiment, the description thereof is omitted.

In this example as well as Example 2, the straightness of the fractured surface was a very high straight line, and no bending or bending was observed. Further, the quality of the cut section was basically the same as that of a laser full cut by the conventional method. Moreover, there was no generation of microcracks or cullet. Further, the magnitude of the bending stress can be freely controlled by the magnitude of electrostatic adsorption.

In Example 5, the bending stress applied to the glass substrate 11 was performed by forming a space below the planned cutting line position of the glass substrate 11 of the table on which the glass substrate 11 was placed. The glass substrate 11 was bent downward in the gap below the planned cutting line position due to the gravity. In this case, the laser diode unit 16 and the condensing lens 18 are disposed below the glass substrate 11 that is curved downward in the gap, and the laser light 17 needs to be irradiated from below the glass substrate 11. Other configurations and operations are the same as those in the second embodiment.

Also in this example, as in Example 2, the straightness of the fractured section was a very high straight line, and no bending or bending was observed. Further, the quality of the cut section was basically the same as that of a laser full cut by the conventional method. Moreover, there was no generation of microcracks or cullet.

FIG. 8 is a conceptual cross-sectional view for explaining a full-body cleaving method for a brittle material in Example 6 of the present invention. Example 6 is an example of full-body cleaving of laminated glass in which two glass substrates are stacked. In this example, two glass substrates 11 and 41 are stacked to form a laminated glass, and this laminated glass has the same configuration as that of Example 2, that is, a bending stress applied to the glass substrate 11 and the glass substrate 41. Is generated by the spacer 31 disposed between the glass substrate 11 and the table 30. The glass substrate 11 and the glass substrate 41 are made of non-alkali glass having a thickness of 0.7 mm to which 3% by weight of Yb is added. The initial crack 13 is formed at one end of the planned cutting line of the glass substrate 11. An initial crack 43 was formed at one end of the planned cutting line. The position of the planned cutting line of the glass substrate 11 and the planned cutting line of the glass substrate 41 is selectively set only to the glass to be cut, and an initial crack that sets the starting point of the cutting is set at one end of the planned cutting line of the glass to be cut. Selectively form. Therefore, the cleaving position is different in each of the laminated glasses, and therefore the position of the initial crack 13 and the position of the initial crack 43 are selectively set at positions shifted laterally as shown in the figure.

The laminated glass in which two glass substrates 11 and 41 were stacked was placed on a table 30 via a glass spacer 31 having a thickness of 5 mm. The glass substrate 11 causes the glass substrate 11 and the glass substrate 41 to bend upward at the position of the planned cutting line, whereby the glass substrate 11 follows the planned cutting line (the initial crack 13 is shown in FIG. 8). Bending stresses 14 and 15 are applied to both sides. Similarly, bending stresses 44 and 45 are applied to the glass substrate 41 along the planned cutting line (the initial crack 43 is shown in FIG. 8) on both sides thereof. Other configurations and operations are the same as those in the second embodiment.

For cleaving, the glass substrate on the inside of the curved surface of the laminated glass, in FIG. 8, the lower glass substrate 11 is cleaved first, and then the glass substrate on the outside of the curved surface, in FIG. 8, the upper glass substrate 41 is cleaved. To do. This is because if the upper glass substrate 41 is cleaved first, the cleaving shifts the position of the initial crack 13 of the lower glass substrate 11 and shifts the position of the preset planned cutting line. Note that this is not the case when the space between the glass substrate 11 and the glass substrate 41 is fixed with an adhesive with sufficient strength.

According to the present embodiment, each of the laminated glasses can be cleaved independently at an arbitrary position depending on whether or not the initial cracks 13 and 43 are present and their positions. Further, even when the laminated glass was cleaved as in this example, the straightness of each fractured section of the laminated glass was an extremely high straight line, and no bending or bending was observed. Further, the quality of the cut section was basically the same as that of a laser full cut by the conventional method. Moreover, there was no generation of microcracks or cullet.
As described above, according to the present embodiment, it is possible to cleave the laminated glass by significantly increasing the cleaving speed as compared with the prior art while realizing the high quality of thermal stress cleaving by the laser. Further, the split section can be cut into a straight line without being bent with respect to the planned cutting line.

FIG. 9 shows a seventh embodiment of the present invention. In this embodiment, a high frequency voltage e is applied from the power source 53 between the electrodes 51 and 52 brought into contact with the front and back surfaces of the glass substrate 11 without using a laser device as a local heat source, and dielectric generated in the glass substrate 11. The glass substrate 11 is locally heated by heat generated by the loss. In FIG. 9, 54 schematically shows the capacitance of the glass substrate 11, and 55 schematically shows the dielectric loss of the glass substrate 11. Other configurations and operations are the same as those in the second embodiment, and thus description thereof is omitted.

FIG. 9 shows a cross-sectional view at a certain position. When the electrodes 51 and 52 are made into a plurality of divided electrodes and the voltage applied to each of them is sequentially changed, the table 30 can be cut along the cutting line without moving. In this case, the cleaving can be realized at higher speed and more stably than in the case of laser light irradiation. Moreover, all the cleaving can also be performed collectively by making an electrode into a continuous body.

  Cutting of glass used for flat panel displays such as liquid crystal displays and plasma displays is currently performed with a diamond cutter, and the necessity of a cleaning process after cutting to generate cullet, and the strength reduction due to the presence of microcracks, etc. Presents the problem. The full body cleaving method of a brittle material according to the present invention can be used for cleaving glass used in flat panel displays such as liquid crystal displays and plasma displays, and cleaving various brittle materials such as quartz, ceramics, and semiconductors.

Characteristic diagram showing changes in radial stress component σ _x and tangential stress component σ _y when there is a temperature rise in the Gaussian distribution centered at the origin for explaining the principle of thermal stress generation in the laser cleaving method It is a conceptual perspective view explaining the conventional laser cleaving method of glass, (a) is a surface scribe, (b) is a schematic diagram in the case of full cut The conceptual perspective view explaining the size effect in the laser cleaving method of the conventional glass, (a) when the cleaving width on both sides of the glass plate is large, (b) is a diagram when the cleaving width on one side of the glass plate is small Conceptual cross-sectional view illustrating the principle of a full-body cleaving method for brittle materials according to the present invention The conceptual perspective view explaining the full body cleaving method of the brittle material in Example 1 of this invention Sectional view of the glass substrate in FIG. Conceptual sectional drawing explaining the full body cleaving method of the brittle material in Example 2 of this invention Conceptual sectional view for explaining a full body cleaving method of a brittle material in Example 3 of the present invention Conceptual sectional drawing explaining the full body cleaving method of the brittle material in Example 7 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Beam spot 2 Glass plate 3 Cleaving direction 4 Heat conduction 5 Beam spot 6 Transmitted light 7 Cleaving line 11 Glass plate 12 Cleavage line 13 Initial cracks 14 and 15 Bending stress 16 Laser unit 17 Laser light 18 Optical system 19 Irradiation point 20 Glass Substrate depth direction 21 Cracks 22, 23 Weight 30 Table 31 Spacer 41 Glass plate 43 Initial cracks 44, 45 Bending stress 51, 52 Electrode 53 Power supply 54 Capacitance 55 Dielectric loss

Claims (16)

A brittle material characterized by applying a deformation stress acting in a thickness direction of the brittle material along a planned fracture line of the brittle material, and scanning the brittle material by scanning a local heat source along the planned fracture line Full body cleaving method of material. The full-body cleaving method for a brittle material according to claim 1, wherein the deformation stress acting in the thickness direction of the brittle material is a bending stress that bends the brittle material in the thickness direction. The full body cleaving method for a brittle material according to claim 1, wherein the deformation stress acting in the thickness direction of the brittle material is a shear stress. The full-body cleaving method for a brittle material according to any one of claims 1 to 3, wherein an initial crack is formed at one end of the planned fracture line of the brittle material. The brittle material full body cleaving method according to any one of claims 1 to 4, wherein the scanning speed of the local heat source is lowered at the initial stage of cleaving and then increased. Bending that selectively forms an initial crack that sets the starting point of cleaving only in the glass to be cleaved in the laminated glass in which a plurality of glass substrates are laminated, and bends in the thickness direction along the cleaved planned line in the glass to be cleaved Applying a stress, scanning a local heat source along the planned cutting line of the glass substrate, and first cleaving the glass substrate on the innermost side of the curved surface of the laminated glass curved by the bending stress; A full-body cleaving method for laminated glass, which comprises cleaving a glass substrate adjacent to the innermost glass substrate. The brittle material according to claim 2, wherein a spacer is disposed at a position immediately below the planned cutting line of the brittle material on the table on which the brittle material is installed, and the vicinity of the planned cutting line of the brittle material is curved upward. Full body cleaving method. The full-body cleaving method for a brittle material according to claim 2, wherein a position immediately below the planned cutting line of the brittle material is pushed up from below by a pin and the vicinity of the planned cutting line of the brittle material is bent upward. The full-body cleaving method for a brittle material according to claim 7 or 8, wherein the positions of both sides of the brittle material curved upward are pressed downward. 10. A full-body cleaving method for a brittle material according to claim 1, wherein a laser beam is used as the local heat source. The full-body cleaving method for a brittle material according to claim 10, wherein the laser beam is a YAG laser beam. The full-body cleaving method for a brittle material according to claim 10, wherein the laser light is CO ₂ laser light. Laser fundamental wave of laser light oscillated by Er: YAG laser or Ho: YAG laser, or a laser selected from Nd: YAG laser, Yb: YAG laser, Nd: YVO ₄ laser and Nd: YLF laser The full-body cleaving method for a brittle material according to claim 11, wherein third to fifth harmonics of laser light oscillating is used. 10. A brittle material according to claim 1, wherein a rare earth element is added to the brittle material, and light emitted from a laser diode or a rare earth solid-state laser is used as a local heat source for the brittle material. Full body cleaving method. The full-body cleaving method for a brittle material according to any one of claims 1 to 9, wherein light emitted from an optical parametric oscillator or a mixed crystal semiconductor laser is used as a local heat source. 10. Full body cleaving of a brittle material according to any one of claims 1 to 9, wherein a dielectric loss based on a high-frequency voltage applied between electrodes in contact with the front and back surfaces of the brittle material is used as a local heat source. Method.