TWI609754B - Fragmentation method of brittle substrate - Google Patents

Abstract

An object of the present invention is to predetermine a position at which a brittle substrate is to be broken, and to prevent the brittle substrate from being unexpectedly broken earlier than a time point at which the fragile substrate should be broken. In the present invention, the blade point 51 having the protruding portion PP and the protruding side portion PS extending from the protruding portion PP and having a convex shape on the first surface SF1 of the brittle substrate 4 slides in a direction from the protruding portion PP toward the side PS. Plastic deformation occurs on one side SF1, and a trench line TL having a trench shape is formed. The crack line CL is formed by extending a crack of the brittle substrate 4 along at least a part of the trench line TL. The brittle substrate 4 is cut along the crack line CL. The step of forming the trench line TL is performed as follows: In the step of forming the crack line CL, the direction in which the crack line CL extends along the trench line TL is the same as the direction in which the trench line TL is formed.

Description

Breaking method of brittle substrate

The invention relates to a method for breaking a brittle substrate.

In the manufacture of electrical devices such as flat display panels and solar cell panels, it is often necessary to break brittle substrates such as glass substrates. First, a scribe line is formed on the substrate, and then the substrate is divided along the scribe line. The scribe line can be formed by machining a substrate using a milling cutter. By sliding or rolling the milling cutter on the substrate, a groove is formed on the substrate by plastic deformation, and at the same time, a vertical crack is formed below the groove. Thereafter, a stress application called a breaking step is performed. The crack is completely advanced in the thickness direction by the breaking step, thereby breaking the substrate. The step of breaking the substrate is mostly performed immediately after the step of forming a scribe on the substrate. However, a step of processing a substrate between the step of forming a scribe line and the step of breaking is also proposed. The step of processing the substrate is, for example, a step of disposing a plurality of members on the substrate. For example, according to the technology of International Patent Publication No. 2002/104078, in a method of manufacturing an organic EL (Electroluminescence) display, a scribe line is formed on a glass substrate in each area that becomes each organic EL display before a sealing cover is installed. . Therefore, it is possible to avoid contact between the sealing cover and the glass milling cutter, which becomes a problem when a scribe is formed on the glass substrate after the sealing cover is provided. In addition, for example, according to the technology of International Patent Publication No. 2003/006391, in a method for manufacturing a liquid crystal display panel, two glass substrates are bonded after forming a scribing line. Thereby, two fragile substrates can be fractured simultaneously in a single fracture step. [Prior Art Literature] [Patent Literature] [Patent Literature 1] International Patent Publication No. 2002/104078 [Patent Literature 2] International Patent Publication No. 2003/006391

[Problems to be Solved by the Invention] According to the above-mentioned prior art, the processing of the fragile substrate is performed after the scribing is formed, and thereafter the fracture step is performed by stress application. This means that vertical cracks already exist when processing a fragile substrate. Because the further extension of the vertical crack in the thickness direction occurs unexpectedly during processing, it may lead to a brittle substrate that should be integrated in the cutting process. In addition, when the substrate processing step is not performed between the step of forming the scribing line and the step of breaking the substrate, it is usually necessary to transport or store the substrate after the step of forming the scribing line and before the step of breaking the substrate. The substrate is unexpectedly broken at this time. Therefore, it is extremely useful if the position where the fragile substrate is broken can be specified by a line that does not accompany a vertical crack (in other words, a line that is in a "crack-free state" described below). In addition, when there is no need to worry about the unexpected breaking as described above, as long as the position of breaking the fragile substrate can be specified by a line not accompanied by a vertical crack, the blade tip is pressed against the fragile substrate even in the line forming step. Further reduction of the load is sufficient. The reduction of the tip load is useful for reducing the wear of the tip or the damage to the surface of the fragile substrate. However, the technique of forming a line that does not accompany a vertical crack that can specify the position of a brittle substrate by sliding the blade tip has not yet been fully studied. Of course, such a line that is not accompanied by a vertical crack is generally considered to be a simple line that is caused by insufficient load on the tool tip. The present invention has been made in order to solve the problems as described above, and an object thereof is to provide a method for cutting a brittle substrate which can specify a position where the brittle substrate is to be broken by a line not accompanied by a vertical crack. [Technical Means for Solving the Problem] A method for breaking a fragile substrate according to one aspect of the present invention includes the following steps a) to c). a) It is formed by sliding a tip of a protruding portion and a side portion extending from the protruding portion and having a convex shape on one surface of the fragile substrate in a direction from the protruding portion toward the side portion to cause plastic deformation on one surface to form A trench line having a trench shape. The trench line is formed in a manner to obtain a state that, below the trench line, the state where the brittle substrate is continuously connected in a direction crossing the trench line is a crack-free state. b) A crack line is formed by extending a crack of the brittle substrate along at least a portion of the trench line. The crack line is below the trench line to continuously connect the fragile substrate in a direction crossing the trench line. c) Break the brittle substrate along the crack line. Step a) is performed in step b) in such a manner that the direction in which the crack line extends along the groove line is the same as the direction in which the groove line is formed. The method for breaking a brittle substrate according to another aspect of the present invention has the following steps a) to c). a) It is formed by sliding a tip of a protruding portion and a side portion extending from the protruding portion and having a convex shape on one surface of the fragile substrate in a direction from the side portion toward the protruding portion to cause plastic deformation on one surface to form A trench line having a trench shape. The trench line is formed in a manner to obtain a state that, below the trench line, the state where the brittle substrate is continuously connected in a direction crossing the trench line is a crack-free state. b) A crack line is formed by extending a crack of the brittle substrate along at least a portion of the trench line. The crack line is below the trench line to continuously connect the fragile substrate in a direction crossing the trench line. c) Break the brittle substrate along the crack line. Step a) is performed in step b) in such a manner that the direction in which the crack line extends along the groove line is opposite to the direction in which the groove line is formed. [Effects of the Invention] According to the present invention, as a line defining a position for breaking a brittle substrate, a groove line without a crack is formed below it. The crack line used as a direct opportunity for breaking is formed by extending the crack along the groove line after it is formed. Thereby, the position where the brittle substrate is broken can be specified by a line not accompanied by a vertical crack.

Hereinafter, embodiments of the present invention will be described based on the drawings. Moreover, in the following drawings, the same or equivalent parts are marked with the same reference numerals, and the description thereof will not be repeated. <Embodiment 1> (Configuration of Cutting Apparatus) Referring to FIG. 1, first, the configuration of the cutting apparatus 50 used in the groove line forming step in the cutting method of the glass substrate 4 (brittle substrate) according to this embodiment will be described. The cutting tool 50 includes a blade tip 51 and a handle 52. The tool tip 51 is held by being fixed to a tool holder 52 serving as a holder thereof. A top surface SD1 (first surface) and a plurality of surfaces surrounding the top surface SD1 are provided on the blade tip 51. The plurality of surfaces include a side surface SD2 (a second surface) and a side surface SD3 (a third surface). The top faces SD1, the side faces SD2, and SD3 (the first to third faces) face different directions and are adjacent to each other. The cutting edge 51 has a vertex where the top surface SD1, the lateral surfaces SD2, and SD3 meet, and the apex of the cutting edge 51 constitutes the protrusion PP of the cutting edge 51. In addition, the side surfaces SD2 and SD3 form a ridge line forming the side portion PS of the blade edge 51. The side portion PS extends linearly from the protrusion portion PP. In addition, since the side portion PS is a ridge line as described above, it has a convex shape extending linearly. The cutting edge 51 is preferably a diamond cutting head. That is, from the viewpoint of reducing the hardness and the surface roughness, the cutting edge 51 is preferably made of diamond. More preferably, the blade tip 51 is made of single crystal diamond. Furthermore, from the viewpoint of crystallography, the top surface SD1 is preferably a {001} surface, and the side surfaces SD2 and SD3 are each a {111} surface. In this case, although the side faces SD2 and the side faces SD3 have different orientations, they are crystallographically equivalent crystal planes. Furthermore, diamonds other than single crystals can be used, for example, polycrystalline diamonds synthesized by a CVD (Chemical Vapor Deposition) method can also be used. Alternatively, sintered diamond may be used in which polycrystalline diamond particles sintered from particulate graphite or non-graphite-like carbon from a bonding material not containing an iron group element are bonded by a bonding material such as an iron group element. The tool holder 52 extends along the axial direction AX. The tool tip 51 is preferably mounted on the tool holder 52 such that the normal direction of the top surface SD1 is substantially along the axial direction AX. (Glass substrate cutting method) In this embodiment, the glass substrate 4 cutting method including the step of sliding the blade 51 (FIG. 1) on the upper surface SF1 of the glass substrate 4 in the direction DA (FIG. 2) )Be explained. The glass substrate 4 to be broken has an upper surface SF1 (one surface) and an opposite lower surface SF2 (the other surface). Referring to FIG. 3, the edge surrounding the upper surface SF1 includes an edge ED1 (first edge) and an edge ED2 (second edge) facing each other. In the example shown in FIG. 3, the edges are rectangular. Therefore, the edges ED1 and ED2 are parallel to each other. In the example shown in FIG. 3, the sides ED1 and ED2 are rectangular short sides. The glass substrate 4 has a thickness direction DT perpendicular to the upper surface SF1. Referring to FIGS. 2 and 3, a trench line TL is formed in step S30. Specifically, the following steps are performed. First, the protruding portion PP and the side portion PS of the blade point 51 are pressed on the upper surface SF1 to the position N1. Details of position N1 will be described later. The pressing of the knife edge 51 refers to FIG. 1 (A), so that the protruding portion PP of the knife edge 51 is arranged between the edge ED1 and the side portion PS on the upper surface SF1 of the glass substrate 4, and the side portion of the knife edge 51 is disposed. PS is performed so that it may be arrange | positioned between the protrusion part PP and the side ED2. Next, the pressed blade point 51 is slid on the upper surface SF1 of the glass substrate 4 (see the arrow in FIG. 3). The blade point 51 (FIG. 1) slides on the upper surface SF1 in a direction DA from the protruding portion PP toward the side portion PS. In other words, the blade point 51 slides in the direction DA that projects the direction from the protruding portion PP toward the side portion PS onto the upper surface SF1. The direction DA is a direction in which the extending direction of the side portion PS near the protrusion PP is projected on the upper surface SF1. The sliding causes plastic deformation on the upper surface SF1. Thereby, a trench line TL (five lines in the figure) having a trench shape is formed on the upper surface SF1. As such, the groove line TL is generated by plastic deformation of the glass substrate 4, and the plastic deformation is sufficiently formed with a lower load that does not cut the surface of the glass substrate, but the glass substrate 4 may be slightly cut. However, it is preferable that such cutting does not generate fine fragments, which are undesirable. The formation of the trench line TL is performed between the position N1 and the position N3. Position N2 is between positions N1 and N3. Therefore, the trench line TL is formed between the positions N1 and N2 and between the positions N2 and N3. The positions N1 and N3 may be located apart from the edge of the upper surface SF1 of the glass substrate 4 as shown in FIG. 3, or one or both of them may be located at the edge of the upper surface SF1. The trench line TL to be formed is separated from the edge of the glass substrate 4 in the former case, and is in contact with the edge of the glass substrate 4 in the latter case. Among the positions N1 and N2, the position N1 is closer to the edge ED1; and among the positions N1 and N2, the position N2 is closer to the edge ED2. Furthermore, in the example shown in FIG. 3, the position N1 is closer to the edge ED1 in the edges ED1 and ED2, and the position N2 is closer to the edge ED2 in the edges ED1 and ED2. Close to either edge ED1 or ED2. When the groove line TL is formed, in this embodiment, the cutting edge 51 is displaced from a position N1 to a position N2, and further from a position N2 to a position N3. That is, referring to FIG. 1, the blade point 51 is displaced in the direction DA from the side ED1 to the side ED2. The direction DA corresponds to a direction in which the axial direction AX extending from the tool tip 51 is projected on the upper surface SF1. In this case, the tool tip 51 is dragged on the upper surface SF1 by the tool holder 52. Referring to FIG. 4, the step of forming the trench line TL can be performed as follows: obtained below the trench line TL, the glass substrate 4 is in a direction DC crossing the extending direction of the trench line TL (lateral direction of FIG. 3 (B)) The state of continuous connection is the state without cracks. In the crack-free state, although the groove line TL is formed by plastic deformation, no crack is formed along it. Therefore, even if an external force such as a bending moment is simply applied to the glass substrate 4 as in the previous breaking step, a break along the groove line TL is not easily generated. Therefore, the breaking step along the trench line TL is not performed in a state without a crack line. In order to obtain a crack-free state, the load applied to the blade tip 51 is adjusted to be small enough to cause no cracks when scribed, and plastic deformation occurs such as to create a state of internal stress that can cause cracks in subsequent steps. degree. The crack-free state can be maintained for a desired time. In order to maintain a crack-free state, as long as operations such as applying excessive stress to the glass substrate 4 in the trench line TL are avoided, for example, avoiding applying a large external stress that may cause damage to the substrate or heating accompanied by a large temperature change, that is, can. During this period, the glass substrate 4 can be transported, stored, or processed. The processing of the glass substrate 4 may be, for example, a step of providing a member (not shown) on the glass substrate 4. Referring to FIG. 5, in step S50 (FIG. 2) after step S30 (FIG. 2), the crack of the glass substrate 4 extends along at least a part of the trench line TL in the thickness direction DT. In FIG. 5, the crack of the glass substrate 4 is extended along a portion between the position N2 and the position N3 in the formed trench line TL (FIG. 3). Thereby, a crack line CL is formed. In this embodiment, the formation of the crack line CL is started with the formation of the auxiliary line AL that intersects the groove line TL at the position N2. The auxiliary line AL may be a general scribe line accompanied by a crack in the thickness direction DT, and may be a strain that releases the internal stress near the trench line TL. The method for forming the auxiliary line AL is not particularly limited, but may be formed using the edge of the upper surface SF1 as a base point as shown in FIG. 5. Referring to FIG. 6, through the crack line CL, below the trench line TL, the glass substrate 4 is continuously connected and disconnected in a direction DC crossing the extending direction of the trench line TL (lateral direction in FIG. 5). Here, the so-called "continuous connection", in other words, the connection without being cut by a crack. Furthermore, in a state of being continuously connected and disconnected as described above, portions of the glass substrates 4 may be in contact with each other through the cracks of the crack line CL. In addition, directly below the trench line TL, there may be a slight residual continuous connection. In this embodiment, the direction in which the crack line CL (FIG. 5) extends along the trench line TL (FIG. 3) (the dotted arrow in FIG. 5) is set to the direction in which the trench line TL is formed (FIG. 3 Solid arrows) are the same. In order to select the extension direction of the crack line CL in this manner, a method for forming the trench line TL may be appropriately selected. According to the study by the inventor, when the groove line TL is formed by sliding the blade tip 51 (FIG. 1) in the direction DA as in this embodiment, if the axial direction AX of the blade tip 51 is relative to the glass substrate 4. The upper surface SF1 is close to vertical, so the extending direction of the crack line CL is the same as that of the trench line TL. Furthermore, in the case where the groove line TL is formed by sliding the blade tip 51 (FIG. 1) in the direction DA as in this embodiment, if the axial direction AX is opposite to the above from the surface SF1 of the glass substrate 4 When the normal line is greatly inclined, the extending direction of the crack line CL is opposite to that of the trench line TL. If the axial direction AX is such an intermediate angle, the extension direction of the crack line CL is unstable and difficult to predict. Therefore, in order to set the extension direction of the crack line CL to be more exactly the same as the formation direction of the groove line TL, as long as the angle of the axial AX (FIG. 1) is adjusted to be closer to the vertical surface SF1, the blade tip 51 is adjusted Just pose. In other words, by increasing the angle AG1 between the upper surface SF1 and the side surface SD3 and reducing the angle AG2 between the upper surface SF1 and the top surface SD1, the extension direction of the crack line CL can be more reliably set to the groove line The extension direction of TL is the same. When the posture of the blade tip 51 (FIG. 1) is adjusted as described above, the angle AG1 increases and the angle AG2 decreases. According to the first experiment using the cutting edge 51 having an angle of 158 ° between the top surface SD1 and the side PS, if the angle AG1 = 5 ° and the angle AG2 = 17 °, the extension direction of the crack line CL and the groove line The TL stretches in the opposite direction. By adjusting the axial direction AX, if the angle AG1 = angle AG2 = 11 ° is set, the extension direction of the crack line CL is the same as the extension direction of the groove line TL. According to the second experiment using the cutting edge 51 with an angle of 165 ° between the top surface SD1 and the side PS, if the angle AG1 = 5 ° and the angle AG2 = 10 °, the extension direction of the crack line CL and the groove line The TL stretches in the opposite direction. By adjusting the axial direction AX, if the angle AG1 = 7 ° and the angle AG2 = 8 °, the extension direction of the crack line CL is the same as that of the groove line TL. In addition, since the protruding portion PP of the blade point 51 is expected to be sharp to some extent, the angle between the top surface SD1 and the side portion PS is preferably about 160 ° or less. Under such conditions, in order to set the extension direction of the crack line CL to be the same as the extension direction of the groove line TL, it is preferable that the angle AG2 ≦ the angle AG1. When the extension direction of the crack line CL is selected as described above, along the groove line TL from the position N2 to the position N3 (see the dotted arrow in FIG. 5), the crack of the glass substrate 4 is in the thickness direction DT (FIG. 6 )stretch. Furthermore, compared with the direction from the position N2 to the position N3, it is difficult to form the crack line CL from the position N2 to the position N1. That is, the easiness of extension of the crack line CL has a direction dependency. Therefore, a crack line CL may be formed between the positions N2 and N3, but may not be formed between the positions N2 and N1. This embodiment is for the purpose of breaking the glass substrate 4 along the positions N2 and N3, and not for separating the glass substrate 4 along the positions N2 and N1. Therefore, the crack line CL must be formed between the positions N2 and N3. On the other hand, the difficulty of forming the crack line CL between the positions N2 and N1 is not a problem. Next, in step S60 (FIG. 2), the glass substrate 4 is cut along the crack line CL. That is, a so-called breaking step is performed. The breaking step can be performed, for example, by applying an external force to the glass substrate 4. For example, the stress applying member is pressed against the lower surface SF2 toward the crack line CL (FIG. 6) on the upper surface SF1 of the glass substrate 4 to apply stress to the glass substrate 4 by cutting the crack line CL. Furthermore, when the crack line CL is completely advanced in the thickness direction DT when it is formed, the formation of the crack line CL and the breaking of the glass substrate 4 may occur simultaneously. The glass substrate 4 is divided as described above. Furthermore, the above-mentioned step of forming the crack line CL is substantially different from the so-called fracture step. The breaking step is to extend the crack that has been formed in the thickness direction to completely separate the substrate. On the other hand, the step of forming the crack line CL is to change the crack-free state obtained by forming the trench line TL to a state having a crack. This change is considered to be caused by the internal stress of the open and crack-free state. Considering the state of plastic deformation when forming the trench line TL, and the magnitude or directionality of internal stress generated when the trench line TL is formed, when using a rotary blade for rolling, the blade tip is used as in this embodiment. The situation of sliding is different. When the sliding of the blade is used, cracks are likely to occur under a wider scribe line. Moreover, it is necessary to apply stress as an opportunity to open the internal stress. In this embodiment, the formation of the auxiliary line AL functions as such an opportunity. Furthermore, although the case where the upper surface SF1 is flat has been described above, the upper surface may be curved. In addition, although the case where the groove line TL is linear has been described, the groove line may be curved. In addition, the case where the glass substrate 4 is used as a brittle substrate has been described. However, the brittle substrate can be made of a brittle material other than glass, for example, ceramic, silicon, compound semiconductor, sapphire, or quartz. (Effect) According to the present embodiment, as a line defining a position where the glass substrate 4 is cut, a groove line TL (FIG. 4) without a crack is formed below it. The crack line CL (FIG. 6) used as a direct opportunity for breaking is formed by forming the trench line TL and extending the crack along it. Thereby, the position where the glass substrate 4 is broken can be specified by the groove line TL which is a line not accompanied by a vertical crack. As described above, the groove line TL, which is a line not accompanied by a vertical crack, is easier to form even if the blade 51 is pressed against the glass substrate 4 with a smaller load than a normal scribe line accompanied by a vertical crack. Reducing the load of the blade tip 51 helps reduce the wear of the blade tip 51 or damage to the upper surface SF1 of the glass substrate 4. In addition, when the blade tip 51 is slid in the direction DA (FIG. 1) as in this embodiment, the local wear of the blade tip 51 is less likely to occur than when the blade tip 51 is slid in the direction DB. Thereby, the life of the blade tip 51 is extended. In addition, the glass substrate 4 (FIG. 3) after the formation of the trench line TL and before the formation of the crack line CL is not easy because the crack line CL has not yet been formed by the groove line TL. Breaking state. By using this state, even if the position where the glass substrate 4 is to be broken is specified in advance, the glass substrate 4 can be prevented from being broken unexpectedly before the time point at which the glass substrate 4 should be broken. For example, it is possible to prevent the glass substrate 4 from being unexpectedly broken during the transportation. In addition, it is possible to prevent the glass substrate 4 from being unexpectedly broken while the glass substrate 4 is being processed several times. In this embodiment, which is different from the second embodiment described below, at the time point when the trench line TL has been formed (FIG. 3), the auxiliary line AL (FIG. 5) has not been formed yet. Therefore, the crack-free state can be maintained more stably without being affected by the auxiliary line AL. (First Variation) Referring to FIG. 7, the first variation relates to a case where the auxiliary line AL and the groove line TL intersect at a position N2 and the opportunity for the crack line CL (FIG. 5) to be formed is insufficient. Referring to FIG. 8, by applying an external force such as a bending moment to the glass substrate 4, the crack extends along the auxiliary line AL in the thickness direction DT, and as a result, the glass substrate 4 is separated. Taking this as an opportunity, the crack line CL started to form. According to this modified example, the crack line CL can be more reliably formed from the trench line TL. Furthermore, in this modification, the strain of the internal stress in the vicinity of the trench line TL is released by separating the glass substrate 4, thereby starting to form the crack line CL. Therefore, the auxiliary line AL itself may be a crack line CL formed by applying a stress to the trench line TL. In FIG. 7, the auxiliary line AL is formed on the upper surface SF1 of the glass substrate 4, but may be formed on the lower surface SF2. In this case, the auxiliary line AL and the trench line TL are in a plan layout and cross each other at the position N2, but they are not in direct contact with each other. (Second Variation) Referring to FIG. 9, in the second variation, in step S30 (FIG. 2), when the trench line TL is formed, it is at position N2 compared with position N3 on the upper surface SF1 of the glass substrate 4. Press the blade tip 51 with greater force. Specifically, the position N4 is taken as the position between the positions N3 and N2, and at the time point when the groove line TL is formed to reach the position N4, the load of the cutting edge 51 is reduced. In other words, compared with the position N3, the load of the cutting edge 51 is increased between the positions N1 and N4, which are the beginning ends of the groove line TL. With this, the load other than the start end portion is reduced, and the crack line CL can be more easily caused to form from the position N2. <Second Embodiment> Hereinafter, a method for cutting the glass substrate 4 according to this embodiment will be described using FIGS. 10 to 12. Referring to FIG. 10, in this embodiment, unlike the first embodiment, the auxiliary line AL is formed before the formation of the trench line TL. The method of forming the auxiliary line AL itself is the same as that shown in FIG. 5 (Embodiment 1). Referring to FIG. 11, the blade point 51 is pressed against the upper surface SF1 in step S20 (FIG. 2), and then, the trench line TL is formed in step S30 (FIG. 2). The method of forming the trench line TL itself is the same as that of FIG. 3 (Embodiment 1). The auxiliary line AL and the groove line TL cross each other at a position N2. Referring to FIG. 12, the glass substrate 4 is then separated along the auxiliary line AL by applying a normal breaking step that generates an external force such as a bending moment to the glass substrate 4. Thereby, as step S50 (FIG. 2), the same crack line CL (see the dotted arrow in the figure) as the first embodiment is started to be formed. Furthermore, in FIG. 10, the auxiliary line AL is formed on the upper surface SF1 of the glass substrate 4, but the auxiliary line AL to separate the glass substrate 4 may be formed on the lower surface SF2 of the glass substrate 4. In this case, the auxiliary line AL and the trench line TL cross each other at the position N2 on the planar layout, but do not directly contact each other. The configuration other than the above is substantially the same as the configuration of the first embodiment. A modification will be described with reference to FIG. 13. In this modification, in step S30 (FIG. 2), when forming the trench line TL, the blade tip 51 is pressed with a stronger force at the position N2 than at the position N3 of the upper surface SF1 of the glass substrate 4. Specifically, the position N4 is taken as the position between the positions N3 and N2, and at the time point when the formation of the groove line TL reaches the position N4, the load of the blade 51 is reduced. In other words, compared with the position N3, the load of the cutting edge 51 is increased between the positions N1 and N4, which are the beginning ends of the groove line TL. With this, the load other than the start end portion is reduced, and the crack line CL can be more easily caused to form from the position N2. <Third Embodiment> In this embodiment, different from the first and second embodiments, the groove line TL has a cutting edge 51 (FIG. 1) on the upper surface SF1 of the glass substrate 4, instead of the direction DA in the direction DB. Formed by sliding. Specifically, the following steps are performed. Referring to FIG. 14, first, the protruding portion PP and the side portion PS of the blade tip 51 are pressed on the upper surface SF1 at the position N3. The pressing of the knife edge 51 refers to FIG. 1 (A), so that the protrusion PP of the knife edge 51 is arranged between the side ED1 and the side portion PS on the upper surface SF1 of the glass substrate 4, and the side portion of the knife edge 51 PS is performed so that it may be arrange | positioned between the protrusion part PP and the side ED2. Next, the pressed blade point 51 slides on the upper surface SF1 of the glass substrate 4 (see the arrow in the figure). The blade point 51 (FIG. 1) is slid on the upper surface SF1 in a direction DB from the side portion PS toward the protruding portion PP. In other words, the blade point 51 (FIG. 1) is slid in a direction DB that projects the direction from the side portion PS toward the protruding portion PP on the upper surface SF1. The direction DB is substantially along the direction in which the extending direction of the side portion PS near the protrusion PP is projected onto the upper surface SF1. By this sliding, the trench line TL is formed in the same manner as in the first embodiment. When the groove line TL is formed, in this embodiment, the cutting edge 51 is displaced from a position N3 to a position N2, and further from a position N2 to a position N1. That is, referring to FIG. 1, the blade point 51 is displaced in a direction from the side ED2 to the side ED1, that is, the direction DB. The direction DB corresponds to a direction opposite to the direction in which the axial direction AX extending from the tool tip 51 is projected on the upper surface SF1. In this case, the tool tip 52 is pushed on the upper surface SF1 by the tool holder 52. Next, as in the first embodiment (FIG. 5), a crack line CL is formed. The extending direction of the crack line CL is the same as that of the first embodiment (the dotted arrow in FIG. 5). Therefore, in this embodiment, the direction in which the crack line CL (FIG. 5) extends along the trench line TL (FIG. 14) (the dotted arrow in FIG. 5) and the direction in which the trench line TL is formed (the solid line in FIG. 14). Arrow) instead. In order to select the extension direction of the crack line CL in this manner, a method for forming the trench line TL may be appropriately selected. Specifically, the posture of the blade tip 51 may be selected in the same manner as in the first embodiment. According to the inventor's research, the extension direction of the crack line CL is not the formation direction of the groove line TL, but is mainly determined by the posture of the blade tip 51. Furthermore, in this embodiment, the same modification examples as the first modification example (FIG. 7 and FIG. 8) and the second modification example (FIG. 9) of the first embodiment may be applied. Also, as in Embodiment 2 and its modification, the auxiliary line AL can be formed before the trench line TL is formed. Next, a modification will be described. First, as in the present embodiment described above, the groove line TL is formed by passing the blade point 51 in the direction DB (FIG. 1) from position N3 through N2 to N1. Thereafter, in this modification, the sliding of the blade tip 51 is turned back at the position N1. Next, at the position N1 to the position N2, the blade point 41 is slid again on the already formed groove line TL. In other words, on the terminal portion of the groove line TL formed by sliding the blade tip 51 in the direction DB, the blade tip 51 is slid in the direction DA again. Taking this re-sliding as an opportunity, the part of the crack line CL from the groove line TL subjected to the above-mentioned re-sliding of the blade tip 51 extends toward the position N3. According to the present modification example, it is not necessary to form the auxiliary line AL (FIG. 5) and the like, and the glass substrate 4 can easily be given an opportunity to start the formation of the crack line CL. This re-sliding can be performed in the direction DB in the same manner as the position N3 to the position N1, but the blade point 51 is not separated from the upper surface SF of the glass substrate 4 at the position N1 (that is, the state where the blade point 51 is in contact with the upper surface SF) Furthermore, it can be turned back and slide in the opposite direction, so that the blade point 51 can be surely moved from the position N1 to the position N2 again on the already formed groove line TL. Furthermore, in this modified example, when the groove line TL is formed by the sliding of the blade edge 51 and the portion subjected to the sliding of the blade edge 51 again is formed, the load of the blade edge 51 can be increased. Specifically, compared with the load from the position N3 to the position N2, the load from the position N2 to the position N1 can be increased. Thereafter, when the blade tip 51 is folded back at the position N1 and slid to the position N2, it is preferable to also maintain the increased load. Thereby, the load of the blade tip 51 in a section other than the section where the blade point 51 is repeatedly slid (that is, the section between the position N1 and the position N2) can be reduced, and the crack line CL is more likely to be caused from the section where the blade point 51 is repeatedly slid. form. <Embodiment 4> Referring to FIG. 15, in this embodiment, when the groove line TL is formed by sliding the blade 51 in the direction DB (FIG. 1), the blade 51 passes through the edge of the glass substrate 4 Position N0 of edge ED1. Thereby, the blade edge 51 cuts the edge of the glass substrate 4 at the position N0. Taking this as an opportunity, as shown in FIG. 16, the crack line CL extends from the position N0 toward the position N3. According to this embodiment, it is not necessary to form the auxiliary line AL (FIG. 5) and the like, and the glass substrate 4 can be easily given an opportunity to start the formation of the crack line CL. In addition, the formation of the crack line CL is started by applying a stress such as a strain that releases the internal stress near the trench line TL to the glass substrate 4 due to a specific portion on the trench line TL. The application of stress is not limited to forming the auxiliary line AL or separating the glass substrate along the line described in Embodiments 1 to 3, or cutting the edge of the glass substrate 4 as described in Embodiment 4. For example, the knife can be used again. It is carried out by pressing a point on or near the formed trench line TL to apply external stress, or by applying heat such as laser light irradiation. <Supplementary note> In the above embodiments, when the sliding direction of the blade edge 51 (FIG. 1) forming the groove line TL is the direction DA, the crack line CL is formed in the same direction as the direction in which the groove line TL is formed. . When the sliding direction of the blade edge 51 (FIG. 1) forming the groove line TL is the direction DB, the crack line CL is formed in a direction opposite to the direction in which the groove line TL is formed. In either case, if the axial direction AX of the blade tip 51 is further inclined from the normal direction of the upper surface SF1 of the glass substrate 4, the extension direction of the crack line CL can be set to the opposite of the above. That is, when the sliding direction of the blade edge 51 (FIG. 1) forming the groove line TL is the direction DA, the crack line CL may be formed in a direction opposite to the direction in which the groove line TL is formed. Moreover, when the sliding direction of the blade edge 51 (FIG. 1) forming the groove line TL is the direction DB, the crack line CL may be formed in the same direction as the direction in which the groove line TL is formed. In this case, it is preferable to set the angle AG2> the angle AG1 in FIG. 1. It should be noted that the position to which the stress is applied as an opportunity to form the crack line CL along the trench line TL may be selected in consideration of the extension direction of the crack line CL. For example, in the case where the auxiliary line AL is formed as a stress application, the position where the auxiliary line AL and the groove line TL intersect is selected in consideration of the extending direction of the crack line CL. Based on the above, a method for dividing a glass substrate (brittle substrate) described in (1) or (2) below can be performed. (1) A method for breaking a first fragile substrate includes the following steps a) to c). a) By causing the tip of the protruding portion and the side portion extending from the protruding portion to have a convex shape on one surface of the fragile substrate, sliding from the protruding portion toward the side portion causes plastic deformation on one surface, thereby A trench line having a trench shape is formed. The trench line is formed as follows: a state where the brittle substrate is continuously connected in a direction intersecting the trench line, that is, a crack-free state is obtained below the trench line. b) A crack line is formed by extending a crack of the brittle substrate along at least a portion of the trench line. With the crack line below the trench line, the brittle substrate is continuously connected and disconnected in a direction crossing the trench line. c) Break the brittle substrate along the crack line. Step a) is performed in a manner that the direction in which the crack line extends along the groove line in step b) is opposite to the direction in which the groove line is formed. (2) A method for breaking a second fragile substrate includes the following steps a) to c). a) The blade tip having a protruding portion and a side portion extending from the protruding portion and having a convex shape is slid in a direction from the side portion toward the protruding portion on one surface of the brittle substrate, thereby causing plastic deformation on one surface, thereby A trench line having a trench shape is formed. The trench line can be formed as follows: obtained under the trench line, a state in which the brittle substrate is continuously connected in a direction crossing the trench line, that is, a crack-free state. b) A crack line is formed by extending a crack of the brittle substrate along at least a portion of the trench line. With the crack line below the trench line, the brittle substrate is continuously connected and disconnected in a direction crossing the trench line. c) Break the brittle substrate along the crack line. Step a) is performed in the same manner as in the direction in which the crack line extends along the groove line in step b) and the direction in which the groove line is formed.

4‧‧‧ glass substrate (brittle substrate)
50‧‧‧ cutting appliances
51‧‧‧Blade
52‧‧‧Handle
AL‧‧‧Auxiliary line
AG1‧‧‧angle
AG2‧‧‧angle
AX‧‧‧Axial
CL‧‧‧ crack line
DA‧‧‧ Direction
DB‧‧‧ Direction
DC‧‧‧ direction
DT‧‧‧thickness direction
ED1‧‧‧side
ED2‧‧‧side
ED3‧‧‧side
ED4‧‧‧Edge
IB‧‧‧Arrow
N0‧‧‧Location
N1‧‧‧Location
N2‧‧‧Location
N3‧‧‧Location
N4‧‧‧Location
SD1‧‧‧Top (first side)
SD2‧‧‧ side (second side)
SD3‧‧‧side (3rd side)
SF1‧‧‧upper surface (one side)
SF2‧‧‧ lower surface (the other side)
S30‧‧‧step
S50‧‧‧step
S60‧‧‧step
TL‧‧‧Trench line
PP‧‧‧ protrusion
PS‧‧‧Side

FIG. 1 (A) is a side view schematically showing the configuration of an apparatus used in the method for cutting a brittle substrate according to the first embodiment, and (B) is a view schematically showing the point of view of an arrow IB in FIG. A plan view of the structure of the blade tip of the appliance. FIG. 2 is a flowchart schematically showing the configuration of a method for cutting a brittle substrate according to the first embodiment of the present invention. 3 is a plan view schematically showing a first step of a method for cutting a fragile substrate according to the first embodiment of the present invention. FIG. 4 is an end view schematically showing a configuration of a groove line formed in a method for cutting a brittle substrate according to Embodiment 1 of the present invention. Fig. 5 is a plan view schematically showing a second step of the method for cutting a fragile substrate according to the first embodiment of the present invention. FIG. 6 is an end view schematically showing a configuration of a crack line formed in a method for breaking a brittle substrate according to Embodiment 1 of the present invention. FIG. 7 is a plan view schematically showing a first step of a method for cutting a fragile substrate according to a first modification of the first embodiment of the present invention. 8 is a plan view schematically showing a second step of a method for breaking a fragile substrate according to a first modification of the first embodiment of the present invention. FIG. 9 is a plan view schematically showing one step of a method for breaking a brittle substrate according to a second modification of the first embodiment of the present invention. FIG. 10 is a plan view schematically showing a first step of a method for cutting a brittle substrate according to Embodiment 2 of the present invention. FIG. 11 is a plan view schematically showing a second step of the method for cutting a fragile substrate according to the second embodiment of the present invention. FIG. 12 is a plan view schematically showing a third step of the method for cutting a fragile substrate according to the second embodiment of the present invention. FIG. 13 is a plan view schematically showing one step of a method for cutting a fragile substrate according to a modification of the second embodiment of the present invention. FIG. 14 is a plan view schematically showing a step of a method for breaking a brittle substrate according to Embodiment 3 of the present invention. FIG. 15 is a plan view schematically showing a first step of a method for cutting a brittle substrate according to Embodiment 4 of the present invention. FIG. 16 is a plan view schematically showing a second step of the method for cutting a fragile substrate according to the fourth embodiment of the present invention.

4‧‧‧ glass substrate (brittle substrate)

AL‧‧‧Auxiliary line

CL‧‧‧ crack line

ED1‧‧‧side

ED2‧‧‧side

ED3‧‧‧side

ED4‧‧‧Edge

N1‧‧‧Location

N2‧‧‧Location

N3‧‧‧Location

SF1‧‧‧upper surface (one side)

TL‧‧‧Trench line

Claims (3)

A method for breaking a fragile substrate, which comprises the following steps: a) by making a blade point having a protruding portion and a side portion extending from the protruding portion and having a convex shape on one surface of the fragile substrate, facing from the protruding portion; The side portion slides in the direction, plastic deformation occurs on the surface, and a groove line having a groove shape is formed. The groove line is formed in a manner to obtain a state below the brittle substrate below the groove line. The state of being continuously connected in the direction crossing the groove line is a crack-free state; b) a crack line is formed by extending a crack of the fragile substrate along at least a part of the groove line; Below the groove line, continuously connecting and disconnecting the fragile substrate in a direction crossing the groove line; and c) breaking the fragile substrate along the crack line; and the step a) is based on the above Step b) is performed in a manner that the direction in which the crack line extends along the groove line is the same as the direction in which the groove line is formed. A method for breaking a fragile substrate, comprising the following steps: a) by making a blade point having a protruding portion and a side portion extending from the protruding portion and having a convex shape on one surface of the fragile substrate, facing from the side portion; The protruding portion slides in the direction, plastic deformation occurs on the surface, and a groove line having a groove shape is formed. The groove line is formed in a manner to obtain a state below the brittle substrate below the groove line. The state of continuous connection in the direction crossing the above-mentioned trench line is a state without cracks; b) forming a crack line by extending a crack of the brittle substrate along at least a part of the groove line; and placing the brittle substrate and the groove line under the groove line by the crack line Continuous connection and disconnection in the direction of crossing; c) breaking the brittle substrate along the crack line; and the above step a) is in step b) in the direction in which the crack line extends along the groove line and the above The trench lines are formed in the opposite direction. For example, the method for breaking a fragile substrate according to claim 1 or 2, wherein the blade edge has adjacent first to third faces, vertices where the first to third faces meet, and the second and third faces described above. The ridgeline is formed, and the protruding portion of the blade tip is formed by the apex, and the side portion of the blade tip is formed by the ridgeline.