JP6645577B2 - Method of cutting brittle substrate - Google Patents

Description

  The present invention relates to a method for cutting a brittle substrate.

  In the manufacture of electrical equipment, such as flat display panels or solar panels, it is often necessary to break brittle substrates. In a typical dividing method, first, a crack line is formed on a brittle substrate. As used herein, the term "crack line" means a crack that has partially progressed in the thickness direction of the brittle substrate and extends linearly on the surface of the brittle substrate. Next, a so-called break step is performed. Specifically, by applying stress to the brittle substrate, the cracks in the crack line are completely advanced in the thickness direction. Thereby, the brittle substrate is cut along the crack line.

  According to Patent Literature 1, the depression on the upper surface of the glass plate occurs at the time of scribing. In Patent Document 1, this depression is called a “scribe line”. At the same time as the engraving of the scribe line, a crack that extends directly downward from the scribe line occurs. As can be seen from the technique of Patent Document 1, in a conventional typical technique, a crack line is formed simultaneously with the formation of a scribe line.

  According to Patent Literature 2, a dividing technique that is significantly different from the typical dividing technique described above is proposed. According to this technique, first, plastic deformation is generated by sliding of a cutting edge on a brittle substrate, whereby a groove shape called “scribe line” in Patent Document 2 is formed. In the present specification, this groove shape is hereinafter referred to as “trench line”. When the trench line is formed, no crack is formed below the trench line. Thereafter, the cracks are formed by extending the cracks along the trench lines. That is, unlike a typical technique, a trench line without a crack is formed once, and then a crack line is formed along the trench line. Thereafter, a normal break process is performed along the crack line.

  The trench line without cracks used in the technique of Patent Document 2 can be formed by sliding the cutting edge with a lower load compared to a typical scribe line with simultaneous formation of cracks. When the load is small, damage applied to the cutting edge is reduced. Therefore, according to this dividing technique, the life of the cutting edge can be extended.

  In Patent Document 2, a cutting instrument having a cutting edge and a shank as a holder thereof is used. The cutting instrument has an axial direction and the shank extends along the axial direction. The trench line is formed by sliding the cutting edge on the brittle substrate. The cutting edge is held by a holder extending along the axial direction. The axial direction is inclined with respect to the upper surface of the brittle substrate. The direction in which the axial direction is projected onto the brittle substrate corresponds to the sliding direction of the cutting edge.

JP-A-9-188534 WO 2015/151755

  According to Patent Document 2, the direction in which the axial direction is projected onto the glass substrate corresponds to the sliding direction of the cutting edge. In other words, there is anisotropy in the action of the substrate cutting edge on the brittle substrate. Therefore, it is necessary to adjust the axial direction according to the sliding direction of the blade edge. Therefore, it is necessary to provide a mechanism for adjusting the posture of the blade edge in the brittle substrate cutting device so that the axial direction corresponds to the sliding direction. In particular, when the sliding direction of the cutting edge is not constant, it is necessary to provide a mechanism for controlling the attitude of the cutting edge. The necessity of adjusting and controlling the posture of the cutting edge can lead to disadvantages such as an increase in the cost of the cutting device, an increase in the time required for the process, and a decrease in the accuracy of the scribe position.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for cutting a brittle substrate, which does not require adjusting the posture of the cutting edge according to the sliding direction of the cutting edge. It is.

A method for cutting a brittle substrate according to one aspect of the present invention includes the following steps a) to e).
a) A brittle substrate having one surface and a thickness direction perpendicular to the one surface is prepared.
b) A tip having an axially symmetric tip in the axial direction is provided, and a tip having a radius of curvature of 3 μm or more and 40 μm or less and a dimension of the tip along the axial direction of 0.5 μm or more is prepared. You.
c) By sliding the tip of the cutting edge on one surface while making the axial direction of the cutting edge perpendicular to one surface of the brittle substrate, the trench line having the groove shape is deformed by plastic deformation. Formed on the surface of The trench line is formed so as to obtain a crackless state in which the brittle substrate is continuously connected below the trench line in a direction crossing the trench line.
d) Crack lines are formed by extending cracks in the brittle substrate in the thickness direction along the trench lines. The brittle substrate has a continuous connection in a direction crossing the trench line below the trench line due to the crack line.
e) The brittle substrate is cut along the crack line.

  Note that the alphabetic characters “a)” to “e)” are given for distinguishing the steps, and do not imply the order of performing the steps.

According to the present invention, when the cutting edge provided with the axially symmetrical tip is slid on one surface of the brittle substrate, the axial direction of the cutting edge is perpendicular to the one surface. As a result, the portion of the cutting edge that comes into direct contact with the brittle substrate is substantially included in the tip portion, and the relationship between the axial direction and the sliding direction is constant without depending on the sliding direction. Becomes Therefore, it is not necessary to adjust the attitude of the cutting edge according to the sliding direction of the cutting edge.

FIG. 2 is a perspective view schematically showing a configuration of a cutting instrument used for a method for cutting a brittle substrate according to Embodiment 1 of the present invention. It is a side view which shows roughly the structure of the cutting tool used for the cutting method of the brittle board in Embodiment 1 of this invention. FIG. 3 is a partial cross-sectional view of the vicinity of a tip end of the cutting edge in FIGS. FIG. 2 is a flowchart schematically showing a configuration of a method for cutting a brittle substrate according to Embodiment 1 of the present invention. FIG. 3 is a top view schematically showing a first step of the method for cutting a brittle substrate according to the first embodiment of the present invention. FIG. 6 is a schematic end view taken along line VI-VI of FIG. 5. FIG. 4 is a top view schematically showing a second step of the method for cutting a brittle substrate according to Embodiment 1 of the present invention. FIG. 8 is a schematic end view taken along line VIII-VIII in FIG. 7. FIG. 9 is a top view schematically showing a first step of a method for cutting a brittle substrate according to Embodiment 2 of the present invention. FIG. 10 is a diagram illustrating a sliding direction of a cutting edge on a brittle substrate in the process of FIG. 9. FIG. 13 is a top view schematically showing a second step of the method for cutting a brittle substrate according to the second embodiment of the present invention. FIG. 13 is a top view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 3 of the present invention. FIG. 13 is a diagram illustrating a sliding direction of a blade edge on a brittle substrate in the step of FIG. 12. FIG. 14 is a top view schematically showing a first step of a method for cutting a brittle substrate according to Embodiment 4 of the present invention. FIG. 15 is a diagram illustrating a sliding direction of a blade edge on a brittle substrate in the step of FIG. 14. FIG. 21 is a top view schematically showing a second step of the method for cutting a brittle substrate according to Embodiment 4 of the present invention. FIG. 15 is a top view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 5 of the present invention. FIG. 18 is a diagram illustrating a sliding direction of a blade edge on a brittle substrate in the step of FIG. 17. FIG. 21 is a side view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 6 of the present invention. FIG. 17 is a flowchart schematically showing a partial configuration of a method for cutting a brittle substrate according to Embodiment 7 of the present invention. FIG. 21 is a top view schematically showing a first step of a method for cutting a brittle substrate according to Embodiment 8 of the present invention. FIG. 22 is a schematic end view taken along line XXII-XXII in FIG. 21. FIG. 21 is a top view schematically showing a second step of the method for cutting a brittle substrate according to Embodiment 8 of the present invention. FIG. 21 is a top view schematically showing a third step of the method for cutting a brittle substrate according to Embodiment 8 of the present invention. FIG. 21 is a flowchart schematically showing a partial configuration of a method for cutting a brittle substrate according to Embodiment 9 of the present invention. FIG. 21 is a top view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 9 of the present invention. FIG. 27 is a schematic sectional view taken along the line XXVII-XXVII in FIG. 26. FIG. 27 is a schematic sectional view taken along the line XXVIII-XXVIII in FIG. 26. FIG. 27 is a schematic sectional view taken along line XXIX-XXIX in FIG. 26. FIG. 21 is a top view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 9 of the present invention. FIG. 31 is a schematic sectional view taken along the line XXXI-XXXI in FIG. 30. FIG. 31 is a schematic sectional view taken along lines XXXII-XXXII in FIG. 30. FIG. 21 is a top view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 9 of the present invention. FIG. 44 is a schematic sectional view taken along a line XXXIV-XXXIV in FIG. 33. FIG. 34 is a schematic sectional view taken along the line XXXV-XXXV in FIG. 33. FIG. 21 is a top view schematically showing one step of a method for cutting a brittle substrate according to Embodiment 9 of the present invention. It is a perspective view which shows roughly the structure of the cutting implement used for the cutting method of the brittle board in Embodiment 10 of this invention. FIG. 38 is a schematic sectional view taken along a line XXXVIII-XXXVIII in FIG. 37. 39 is an example of the surface shape of the tip of the blade along the line AA in FIG. 38. 39 is an example of the surface shape of the tip of the blade along the line AA in FIG. 38.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

<First Embodiment>
FIGS. 1 and 2 are perspective views schematically showing the configuration of a cutting tool 50 used in the method of cutting the glass substrate 4 (brittle substrate) in the present embodiment. FIG. 3 is a partial cross-sectional view of the vicinity of the tip end 51N of the cutting edge 51 in FIGS. 1 and 2.

  The cutting instrument 50 has a cutting edge 51 and a support portion 52. The blade edge 51 and the support portion 52 may be an integral member made of the same material.

  As shown in FIG. 3, the cutting edge 51 is provided with a tip portion 51N having axial symmetry in the axial direction AX. That is, the surface of the tip portion 51N is a surface obtained by rotating the curve around the axial direction AX. The surface of the tip portion 51N is a curved surface having a convex shape toward the outside. The surface of the tip portion 51N may be a part of a spherical surface. The radius of curvature of the tip portion 51N is preferably 3 μm or more and 40 μm or less. The surface of the tip 51N may be a conical surface, and the apex of the conical surface may be rounded. The dimension of the tip portion 51N along the axial direction AX is typically 0.5 μm or more, usually 1.0 μm or more is sufficient, and preferably 2.0 μm or more. Thus, a portion of the cutting edge 51 that comes into direct contact with the glass substrate 4 is generally substantially included in the distal end portion 51N. The above-mentioned “axial symmetry” is preferably an ideal geometrical axial symmetry, but may be a substantial axial symmetry in view of the action on the glass substrate 4. The latter is referred to as “pseudo-axial symmetry” in this specification, and details thereof will be described in a tenth embodiment described later.

  Preferably, the entire cutting edge 51 including the tip 51N has axial symmetry in the axial direction AX. In FIG. 3, the cutting edge 51 has a right-cone shape having axial symmetry in the axial direction AX, and a tip 51N is provided at a vertex of the right-cone shape. In the cross section including the axial direction AX (FIG. 3), if the shape of the distal end portion 51N is ignored, the angle of the apex of the right circular cone is preferably 120 ° or more, and more preferably 130 ° or more. This angle is preferably 160 ° or less, and more preferably 150 ° or less.

  It is preferable that the support part 52 extends along the axial direction AX. The entire cutting tool 50 may have axial symmetry in the axial direction AX.

  Next, a method of cutting the glass substrate 4 will be described below with reference to a flowchart shown in FIG.

  In step S10 (FIG. 4), a glass substrate 4 (FIG. 2) to be cut is prepared. The glass substrate 4 has an upper surface SF1 (one surface) and an opposite lower surface SF2 (other surface). An edge ED is provided on the upper surface SF1. The upper surface SF1 is typically flat. In the example shown in FIG. 5, the edge ED has a rectangular shape. The glass substrate 4 has a thickness direction DT perpendicular to the upper surface SF1. In step S20 (FIG. 4), the above-described cutting instrument 50 having the cutting edge 51 (FIGS. 1 to 3) is prepared.

  Referring to FIG. 5, in step S30 (FIG. 4), a trench line TL having a linear shape is formed. Specifically, the following steps are performed.

  First, the tip 51N of the blade 51 (FIGS. 1 to 3) is pressed against the upper surface SF1 at the position N1. Thereby, the tip portion 51N comes into contact with the glass substrate 4. The position N1 is preferably away from the edge ED of the upper surface SF1 of the glass substrate 4, as shown. In this case, when the sliding of the cutting edge 51 starts, the cutting edge 51 is prevented from colliding with the edge ED of the upper surface SF1 of the glass substrate 4.

  Next, the tip 51N of the cutting edge 51 is slid on the upper surface SF1 while making the axial direction AX of the cutting edge 51 perpendicular to the upper surface SF1 of the glass substrate 4 (see the arrow in FIG. 5). When sliding, a load is applied to the cutting edge 51 from outside. This load direction is perpendicular to the upper surface SF1. The sliding causes plastic deformation on the upper surface SF1.

  Due to this plastic deformation, a trench line TL having a groove shape (see FIG. 6) is formed on the upper surface SF1 of the glass substrate 4. The trench line TL is a crackless state in which the glass substrate 4 is continuously connected below the trench line TL in a direction DC (FIG. 6) crossing the extending direction of the trench line TL (the horizontal direction in FIG. 5). It is formed to obtain a state. In the crackless state, the trench line TL due to plastic deformation is formed, but no crack is formed along the trench line TL. In order to obtain a crackless state, the load applied to the cutting edge 51 is small enough not to cause cracking at the time of forming the trench line TL, and creates a state of internal stress capable of causing cracking in a later step. It is adjusted so as to be large enough to cause severe plastic deformation.

  The trench line TL is preferably generated only by the plastic deformation of the glass substrate 4, and in this case, no shaving occurs on the upper surface SF1 of the glass substrate 4. In order to avoid shaving, the load on the cutting edge 51 need not be excessively high. Since there is no scraping, it is possible to avoid generation of undesirable fine fragments on the upper surface SF1. However, some scraping can usually be tolerated.

  The formation of the trench line TL is performed by sliding the leading end 51N of the cutting edge 51 from the position N1 to the position N3e via the position N2 between the position N1 and the position N3e. The position N2 is apart from the edge ED of the upper surface SF1 of the glass substrate 4. The position N3e is located at the edge ED of the upper surface SF1 of the glass substrate 4. Therefore, the cutting edge 51 slid to form the trench line TL finally reaches the position N3e. The crackless state is maintained when the cutting edge 51 is located at the position N2, and is further maintained until the cutting edge 51 reaches the position N3e. When the cutting edge 51 reaches the position N3e, the cutting edge 51 cuts down the edge ED of the upper surface SF1 of the glass substrate 4.

  Referring to FIG. 7 and FIG. 8, the above-mentioned downcut causes minute destruction at position N3e. Starting from this destruction, cracks occur so as to release the internal stress near the trench line TL. Specifically, cracks in the glass substrate 4 in the thickness direction DT extend from the position N3e located at the edge ED of the upper surface SF1 of the glass substrate 4 along the trench line TL (see the arrow in FIG. 7). In other words, the formation of the crack line CL is started. Thereby, as step S50 (FIG. 4), a crack line CL is formed from the position N3e to the position N1. The direction in which the crack line CL extends along the trench line TL (arrow in FIG. 7) is opposite to the direction in which the trench line TL is formed (arrow in FIG. 5).

  In order to more reliably form the crack line CL, the speed at which the cutting edge 51 slides from the position N2 to the position N3e may be lower than the speed at the position N1 to the position N2. Similarly, the load applied to the cutting edge 51 from the position N2 to the position N3e may be larger than the load from the position N1 to the position N2 within a range where the crackless state is maintained.

  Below the trench line TL, the continuous connection of the glass substrate 4 in the direction DC (FIG. 8) intersecting with the extending direction of the trench line TL (the horizontal direction in FIG. 7) is broken by the crack line CL. Here, the “continuous connection” is, in other words, a connection that is not interrupted by a crack. Note that, in the state where the continuous connection is broken as described above, the portions of the glass substrate 4 may be in contact with each other through cracks in the crack lines CL. Further, a slightly continuous connection may be left directly below the trench line TL.

  Next, in step S60 (FIG. 4), the glass substrate 4 is cut along the crack line CL. That is, a so-called break step is performed. The breaking step can be performed by applying an external force to the glass substrate 4. For example, by pressing a stress applying member (for example, a member called “break bar”) on lower surface SF2 toward crack line CL (FIG. 8) on upper surface SF1 of glass substrate 4, cracks in crack line CL are formed. Is applied to the glass substrate 4. If the crack line CL completely advances in the thickness direction DT at the time of formation, the formation of the crack line CL and the division of the glass substrate 4 occur simultaneously.

  Thus, the glass substrate 4 is divided. The process of forming the crack line CL is essentially different from the so-called break process. The breaking step is to completely separate the substrate by further extending the cracks already formed in the thickness direction. On the other hand, the step of forming the crack line CL causes a change from a crackless state obtained by forming the trench line TL to a state having cracks. This change is considered to be caused by release of the internal stress of the crackless state.

  According to the present embodiment, when the blade edge 51 provided with the axially symmetrical tip portion 51N is slid on the upper surface SF1 of the glass substrate 4, the axial direction AX of the blade edge 51 with respect to the upper surface SF1 is changed. Vertical (FIG. 2). Accordingly, the relationship between the axial direction AX and the sliding direction DA becomes constant without depending on the direction DA in which the tip end portion 51N of the cutting edge 51 is slid. Therefore, it is not necessary to adjust the attitude of the cutting edge 51 according to the sliding direction DA of the cutting edge 51.

  In other embodiments described later, when the blade edge 51 is slid on the upper surface SF1 of the glass substrate 4 for forming the trench line TL, the axial direction AX of the blade edge 51 with respect to the upper surface SF1 is changed. Vertical. Therefore, the same effects as in the present embodiment can be obtained in other embodiments.

<Embodiment 2>
In the first embodiment, trench line TL has a linear shape. On the other hand, in the present embodiment, trench line TL includes a curved shape. Hereinafter, a process of forming the trench line TL will be described in detail.

  Referring to FIG. 9, in the present embodiment, trench line TL has a curved shape. Correspondingly, the step of forming the trench line TL includes a step of sliding the tip 51N of the cutting edge 51 in the direction DA1 (first direction), and thereafter, a step of sliding the tip 51N in the direction DA2 (second Direction).

  Referring to FIG. 10, direction DA2 is different from direction DA1. The sliding direction DA of the tip 51N of the cutting edge 51 continuously changes between the direction DA1 and the direction DA2, as shown by the broken line in the figure.

  Subsequently, a crack line is formed along the trench line TL. Referring to FIG. 11, glass substrate 4 is cut along this crack line.

  Since the configuration other than the above is substantially the same as the configuration of the above-described first embodiment, the same or corresponding elements have the same reference characters allotted, and description thereof will not be repeated.

  In the present embodiment, the sliding direction DA changes between the direction DA1 and the direction DA2. Since the tip end 51N of the cutting edge 51 has axial symmetry and the axial direction AX of the cutting edge 51 is perpendicular to the upper surface SF1 (FIG. 2), the change in the sliding direction DA described above is caused by the axial It does not affect the relationship between the direction AX and the sliding direction DA. Therefore, it is not necessary to adjust the attitude of the cutting edge 51 according to the sliding direction DA of the cutting edge 51. In other words, even when the trench line TL including the curved portion is formed, it is not necessary to adjust the attitude of the cutting edge 51 according to the sliding direction DA of the cutting edge 51.

<Embodiment 3>
Referring to FIG. 12, in the present embodiment, trench line TL substantially includes a closed curve. Correspondingly, as shown in FIG. 13, the sliding direction DA changes in all directions as shown by the broken lines in the figure. In other words, the tip 51N of the cutting edge 51 is slid in all directions. Since the configuration other than the above is substantially the same as the configuration of the second embodiment described above, the same or corresponding elements have the same reference characters allotted, and description thereof will not be repeated.

<Embodiment 4>
Referring to FIGS. 14 and 15, in the present embodiment, when trench line TL is formed, tip 51N of cutting edge 51 is brought into contact with upper surface SF1 of glass substrate 4 while tip 51N is formed. The heading direction DA is discontinuously changed from the direction DA1 to the direction DA2.

  Subsequently, a crack line is formed along the trench line TL. Referring to FIG. 16, glass substrate 4 is cut along the crack line.

  Since the configuration other than the above is substantially the same as the configuration of the second embodiment described above, the same or corresponding elements have the same reference characters allotted, and description thereof will not be repeated.

  At the moment when the direction DA changes discontinuously, the cutting edge 51 is almost stopped relative to the glass substrate 4. If the posture of the cutting edge 51 is adjusted in such a stopped state, the tip portion 51N of the cutting edge 51 or the glass substrate 4 is likely to be damaged. According to the present embodiment, it is not necessary to adjust the attitude of the cutting edge 51, so that the above-described damage can be avoided.

<Embodiment 5>
Referring to FIG. 17, trench line TL formed in the present embodiment includes a trench line TL1 and a trench line TL2 which are parallel to each other. The trench lines TL1 and TL2 are formed alternately. When the trench line TL1 is formed, the direction DA of the tip 51N while the tip 51N of the cutting edge 51 is in contact with the upper surface SF1 of the glass substrate 4 is defined as the direction DA1. When the trench line TL2 is formed, the direction DA of the tip 51N while the tip 51N of the cutting edge 51 is in contact with the upper surface SF1 of the glass substrate 4 is defined as the direction DA2. The direction DA1 and the direction DA2 are opposite to each other. Therefore, as shown in FIG. 18, the direction DA to which the distal end portion 51N is directed is either the direction DA1 or the direction DA2. In the formation of the trench line TL, the sliding direction DA is changed discontinuously between the direction DA1 and the direction DA2.

  Since the configuration other than the above is substantially the same as the configuration of the above-described fourth embodiment, the same or corresponding elements have the same reference characters allotted, and description thereof will not be repeated.

  Assuming that both the trench line TL1 and the trench line TL2 are formed by sliding in the direction DA1, the cutting edge 51 is moved from one edge (the left edge in the drawing) to the other edge (the right edge in the drawing). After the trench line TL1 is formed by moving the cutting edge 51, the operation only for returning the cutting edge 51 to the one edge is required. On the other hand, according to the present embodiment, trench line TL2 is formed during this operation. Thereby, the time required for the process is reduced. Therefore, productivity can be improved.

<Embodiment 6>
Referring to FIG. 19, in each of the above-described embodiments, when forming trench line TL, cutting edge 51 may be rotated around axial direction AX (see rotation RT in the drawing). The rotation RT may be performed while sliding the tip 51N of the cutting edge 51 on the upper surface SF1 of the glass substrate 4. The rotation RT may be performed all the time during the sliding, or may be performed intermittently. Alternatively, the rotation RT may be performed without sliding the tip end 51N of the cutting edge 51 on the upper surface SF1 of the glass substrate 4. In this case, the cutting edge 51 is rotated with the cutting edge 51 stopped or with the cutting edge 51 separated from the glass substrate 4.

  According to the present embodiment, local wear of the cutting edge 51 can be avoided. Therefore, the life of the cutting edge 51 can be extended.

<Embodiment 7>
In each of the above-described embodiments, when the trench line TL is formed, the lubricant may be supplied to a position where the tip 51N of the cutting edge 51 slides on the upper surface SF1 of the glass substrate 4. . In other words, in the step of forming the trench line TL (FIG. 4: step S30), as shown in FIG. 20, the step S31 of supplying the lubricant and the cutting edge 51 is slid at the position where the lubricant is supplied. Step S32 may be included. As the lubricant, for example, a lubricating oil that is liquid at room temperature or a solid lubricant at room temperature can be used.

  In each of the above-described embodiments, the cutting edge 51 that slides on the upper surface SF1 of the glass substrate 4 is easily worn when the trench line TL is formed. According to the present embodiment, such wear can be suppressed.

<Embodiment 8>
Referring to FIG. 21, in step S10 (FIG. 4), a glass substrate 4 similar to that of the first embodiment is prepared. However, in the present embodiment, assist line AL is provided on upper surface SF1 of glass substrate 4 in advance. Referring to FIG. 22, assist line AL has assist trench line TLa and assist crack line CLa. The assist trench line TLa has a groove shape. The assist crack line CLa is configured by a crack of the glass substrate 4 in the thickness direction DT extending along the assist trench line TLa.

  In the present embodiment, the assist line AL is provided on the upper surface SF1 of the glass substrate 4 by a process of simultaneously forming the assist trench line TLa and the assist crack line CLa. Such an assist line AL can be formed by a conventional typical scribing method. For example, such an assist line AL can be formed by the cutting edge riding over the edge ED of the upper surface SF1 of the glass substrate 4 and moving on the upper surface SF1, as shown by the arrow in FIG. It is preferable that the cutting edge is rotatably held (wheel type). In other words, it is preferable that the blade edge is not sliding on the glass substrate 4 but is rotating.

  The starting point of the assist line AL is the edge ED in FIG. 21, but may be away from the edge ED. Further, assist line AL may be formed by a method similar to the method of forming crack line CL in any of the first to seventh embodiments described above. Further, the above-described assist line AL may be formed using a blade that is slid on the glass substrate 4. Alternatively, the assist line AL described above may be formed using the cutting edge 51 in order to facilitate the preparation of the cutting edge for the assist line AL described above.

  Next, in step S20 (FIG. 4), the same cutting edge 51 as in the first embodiment is prepared.

  Referring to FIG. 23, next, in step S30 (FIG. 4), trench line TL is formed. In the present embodiment, the formation of trench line TL is performed by sliding blade edge 51 from position N1 to position N3a via position N2 between position N1 and position N3a. The position N3a is located on the assist line AL. The position N2 is arranged between the position N1 and the position N3a. Preferably, the cutting edge 51 is slid to a position N4 beyond the position N3a on the assist line AL. Position N4 is preferably remote from edge ED.

  The cutting edge 51 slid as described above to form the trench line TL intersects the assist line AL at the position N3a. This intersection causes minute destruction at the position N3a. Starting from this destruction, cracks occur so as to release the internal stress near the trench line TL. Specifically, cracks in the glass substrate 4 in the thickness direction extend from the position N3a located on the assist line AL along the trench line TL (see the arrow in FIG. 24). In other words, the formation of the crack line CL (FIG. 24) is started. Thereby, as step S50 (FIG. 4), a crack line CL is formed from the position N3a to the position N1.

  After reaching the position N3a, the cutting edge 51 is separated from the glass substrate 4. Preferably, the cutting edge 51 is separated from the glass substrate 4 after sliding over the position N3a to the position N4.

  Next, in step S60 (FIG. 4), similarly to the first embodiment, glass substrate 4 is cut along crack line CL. As described above, the method for cutting the glass substrate 4 of the present embodiment is performed.

  In the first embodiment, the cutting edge 51 cuts down the glass substrate 4 at the position N3e (FIG. 5). On the other hand, according to the present embodiment, such an undercut is not required. This can avoid damage to the cutting edge 51 or the glass substrate 4 that can occur when the cutting edge 51 cuts down.

  It should be noted that the start of the formation of the crack line CL may not be obtained simply by the intersection of the cutting edge 51 with the assist line AL. In such a case, the glass substrate 4 may be cut along the assist line AL after the trench line TL intersecting with the assist line AL is formed. Thereby, it is possible to obtain a trigger for starting the formation of the crack line CL.

<Embodiment 9>
Referring to FIG. 26, first, as in the other embodiments, glass substrate 4 is prepared (FIG. 4: step S10). Further, a cutting edge 51 is prepared (FIG. 4: step S20).

  Next, as in the other embodiments, the tip 51N of the cutting edge 51 is slid on the upper surface SF1 while the axial direction AX of the cutting edge 51 is perpendicular to the upper surface SF1 of the glass substrate 4. This sliding is performed from the start point N1 to the end point N3 via the intermediate point N2. Thereby, plastic deformation is generated on the upper surface SF1 of the glass substrate 4. As a result, a trench line TL extending from the start point N1 to the end point N3 via the intermediate point N2 is formed on the upper surface SF1 (FIG. 4: step S30).

  The step of forming each of the trench lines TL includes a step of forming a low load section LR as a part of the trench line TL (FIG. 25: step S30L) and a step of forming a high load section HR as a part of the trench line TL. (FIG. 25: Step S30H). In FIG. 26, a low load section LR is formed from the start point N1 to the middle point N2, and a high load section HR is formed from the middle point N2 to the end point N3. The load applied to the cutting edge 51 in the step of forming the high load section HR is higher than the load used in the step of forming the low load section LR. Conversely, the load applied to the cutting edge 51 in the step of forming the low load section LR is lower than the load used in the step of forming the high load section HR, for example, 30 to 50 times the load of the high load section HR. %. Therefore, the width of the trench line in the high load section HR is larger than the width of the low load section LR. Also, as shown in FIG. 27, the depth of the high load section HR is larger than the depth of the low load section LR. The cross section of trench line TL has, for example, a V-shape having an angle of about 150 °.

  Since a high load is applied to the cutting edge 51 in the high load section HR, it is preferable that the distance of the high load section HR is small in consideration of the life of the cutting edge 51. Further, when the load is changed during the formation of the trench line TL, the scribe speed is preferably reduced in the high load section HR in order to sufficiently increase the load in the high load section HR at a smaller distance. That is, since it is difficult to instantaneously increase the load on the cutting edge 51, scribing is performed while the load is increased in a certain section until the load reaches a predetermined value, starting from the position N2. . Therefore, by reducing the speed in the high load section HR, the load can be increased at a smaller distance, and the entire distance of the high load section HR can be reduced.

  In the step of forming the trench line TL, a crackless state in which the glass substrate 4 is continuously connected immediately below the trench line TL in the direction DC (FIGS. 28 and 29) crossing the trench line TL is obtained. Is done as follows. For this purpose, the load applied to the cutting edge is large enough to cause plastic deformation of the glass substrate 4 and small enough not to generate cracks starting from the plastically deformed portion.

  Next, a step of forming a crack line (FIG. 4: step S50) is performed as follows.

  Referring to FIGS. 30 to 32, first, an assist line AL that intersects high load section HR is formed on upper surface SF1 of glass substrate 4. The assist line AL involves a crack that penetrates in the thickness direction of the glass substrate 4. The assist line AL can be formed by a normal scribe method.

  Next, the glass substrate 4 is separated along the assist line AL. This separation can be performed by a normal breaking step. Triggered by this separation, cracks in the glass substrate 4 in the thickness direction extend along the trench line TL only in the high load section HR of the trench line TL.

  33 and 34, crack line CL is formed along part of trench line TL as described above. Specifically, a crack line CL is formed in a portion between the side newly generated by separation and the midpoint N2 in the high load section HR. The direction in which the crack line CL is formed is opposite to the direction DA (FIG. 26) in which the trench line TL is formed.

  Note that a crack line CL is not easily formed in a portion between a side newly generated by separation and the end point N3. This is presumably because the distribution of the internal stress generated near the trench line TL has anisotropy depending on the direction in which the trench line TL is formed.

  Referring to FIG. 35, immediately below the high load section HR of trench line TL by crack line CL, glass substrate 4 is disconnected from continuous connection in a direction DC intersecting with the extending direction of trench line TL. Here, the “continuous connection” is, in other words, a connection that is not interrupted by a crack. Note that, in the state where the continuous connection is broken as described above, the portions of the glass substrate 4 may be in contact with each other through cracks in the crack lines CL.

  Next, a breaking step of dividing the glass substrate 4 along the trench line TL is performed (FIG. 4: step S60). At this time, by applying a stress to the glass substrate 4, the crack is extended along the low load section LR starting from the crack line CL. The direction in which the cracks extend (the arrow PR in FIG. 36) is opposite to the direction DA (FIG. 26) in which the trench line TL is formed.

  Thus, the glass substrate 4 is divided.

  According to the present embodiment, when forming trench line TL (FIGS. 26 and 27) for defining the position where glass substrate 4 is to be divided, the cutting edge is lower in low load section LR than in high load section HR. The load applied to 51 (FIG. 1) is reduced. Thereby, damage to the cutting edge 51 can be reduced.

  When the low load section LR of the low load section LR and the high load section HR is in a crackless state (FIGS. 33 and 34), there is no crack in the low load section LR that is a starting point at which the glass substrate 4 is divided. . Therefore, when an arbitrary process is performed on the glass substrate 4 in this state, even if an unexpected stress is applied to the low load section LR, unintended division of the glass substrate 4 hardly occurs. Therefore, the above processing can be performed stably.

  When both the low load section LR and the high load section HR are in a crackless state (FIGS. 26 and 27), no crack serving as a starting point at which the glass substrate 4 is divided is present in the trench line TL. Therefore, when performing arbitrary processing on the glass substrate 4 in this state, even if an unexpected stress is applied to the trench line TL, unintended division of the glass substrate 4 hardly occurs. Therefore, the above processing can be performed more stably.

  The trench line TL is formed before the formation of the assist line AL. This can prevent the assist line AL from affecting the formation of the trench line TL. In particular, it is possible to avoid abnormal formation immediately after the cutting edge 51 passes over the assist line AL for forming the trench line TL.

<Embodiment 10>
In the present embodiment, a case where the tip of the cutting edge has the pseudo-axial symmetry mentioned in the first embodiment will be described.

  FIG. 37 is a perspective view schematically showing a configuration of a cutting instrument 150 in the present embodiment. The cutting instrument 150 has a cutting edge 151 provided with a tip 151N instead of the cutting edge 51 provided with a tip 51N (FIG. 2). The cutting edge 151 has a polygonal pyramid shape having a rounded vertex. The polygonal pyramid has a side surface SD and a ridge line RG. A tip 151N is provided at the apex of the polygonal pyramid.

  FIG. 38 is a schematic sectional view taken along the line XXXVIII-XXXVIII in FIG. 37 and perpendicular to the axial direction AX. A line XXXVIII-XXXVIII (FIG. 37) corresponds to a cross section perpendicular to the axial direction AX near the boundary between the tip portion 151N of the cutting edge 151 and other portions. Hereinafter, the shape of the distal end portion 151N in this sectional view will be described.

  The shape of the tip 151N is an n-sided polygon (n ≧ 3) corresponding to the polygonal pyramid, and is preferably a regular polygon. FIG. 38 illustrates a hexagon (n = 16). The tip portion 151N has n points PT corresponding to the n ridge lines RG (FIG. 37), and each of the points PT is in contact with the circumscribed circle CC. Further, the tip portion 151N has n sides SD corresponding to the n side surfaces SD (FIG. 37), and each of the sides SD has a dimension DS. With the size of the circumscribed circle CC constant, the larger the value of n, the smaller the dimension DS, and as a result, the cross-sectional shape of the tip 151N approaches a circle. Therefore, as n increases, the axial symmetry of the tip 151N in the axial direction AX approaches the ideal geometric symmetry. Therefore, if n is somewhat large, it can be said that the tip portion 151N has axial symmetry in its function. That is, it can be said that the tip portion 151N has the pseudo-axial symmetry described above. According to the study of the present inventor, if the dimension DS is 1 μm or less, it can be said that the tip portion 151N has pseudo-axial symmetry. N that satisfies this condition can be calculated, for example, from the angle of the tip 151N and the radius of curvature of the tip 151N near the axis AX. An example of this calculation will be described below.

  FIG. 39 corresponds to a cross-sectional view taken along line AA of FIG. 38, and illustrates surface shapes of tips 151Na to 151Nc having a radius of curvature R = 3 μm near axis AX as an example of tip 151N. I have. Each of the tip portions 151Na to 151Nc has a tip angle of 120 °, 130 °, and 140 °. Since the radius of curvature R near the axis AX is 3 μm, when the dimension of the tip 51N along the axial direction AX is 1 μm, each of the tips 151Na to 151Nc has a diameter of 5.08 μm, 5.62 μm and It has 6.56 μm. In other words, each of the tips 151Na to 151Nc has a circumference of 15.96 μm, 17.65 μm, and 20.60 μm. Therefore, n for setting the dimension DS (FIG. 38) to 1 μm or less is 16 or more for the tip 151Nb, 18 or more for the tip 151Nb, and 21 or more for the tip 151Nc.

  FIG. 40 corresponds to a cross-sectional view taken along line AA in FIG. 38 and illustrates, as an example of the tip 151N, the surface shapes of the tips 151Ni to 151Nk having a radius of curvature R = 5 μm near the axis AX. I have. Each of the tip portions 151Ni to 151Nk has a tip angle of 120 °, 130 °, and 140 °. Since the radius of curvature R near the axis AX is 5 μm, when the dimension of the tip 51N along the axial direction AX is 1 μm, each of the tips 151Ni to 151Nk has a diameter of 6.17 μm, 6.51 μm and 7.26 μm. In other words, each of the tips 151Ni to 151Nk has a circumference of 19.38 μm, 20.45 μm and 22.80 μm. Accordingly, n for setting the dimension DS (FIG. 38) to 1 μm or less is 20 or more for the tip 151Ni, 21 or more for the tip 151Nj, and 23 or more for the tip 151Nk.

  Based on the study results in FIGS. 39 and 40, for example, if n ≧ 16, pseudo axial symmetry may be obtained. Therefore, n is preferably 16 or more. If n ≧ 25, pseudo-axial symmetry can be obtained while using any tip angle and radius of curvature within a normally used range. In view of the workability and working time of the work for forming the tip, n is preferably not unnecessarily large, and therefore n is preferably 25 or less.

  In order to obtain the cutting edge 151, for example, a substantially polygonal pyramid shape may be given to the tip of the diamond piece by polishing the tip of a piece of material (for example, diamond piece) having a polygonal column shape a plurality of times. As a modified example, R chamfering may be performed on the ridgeline RG (FIG. 37). As a result, the straight portion of the side SD (FIG. 38) is shortened, so that the shape of the tip 151N becomes closer to a circle. That is, the axial symmetry of the tip 151N approaches a more ideal one. In this case, a pseudo-axial symmetry can be obtained even with a smaller n.

  In each of the above embodiments, the case where the edge of the upper surface SF1 is rectangular is illustrated, but another shape may be used. Although the case where the upper surface SF1 is flat has been described, the upper surface may be curved. Although the case where the trench line TL is linear has been described, the trench line TL may be curved. Although the case where the glass substrate 4 is used as the brittle substrate has been described, the brittle substrate may be made of a brittle material other than glass, and may be made of, for example, ceramics, silicon, a compound semiconductor, sapphire, or quartz.

AL Assist line CL Crack line AX Axial direction SF1 Upper surface (one surface)
HR High load section LR Low load section TL, TL1, TL2 Trench line 4 Glass substrate (brittle substrate)
50, 150 Cutting tool 51, 151 Cutting edge 51N, 151N, 151Na to 151Nc, 151Ni to 151Nk Tip 52 Support

Claims (9)

a) providing a brittle substrate having one surface and a thickness direction perpendicular to the one surface; and b) preparing a cutting edge provided with a tip having axial symmetry in the axial direction. And c) by sliding the tip of the cutting edge on the one surface while making the axial direction of the cutting edge perpendicular to the one surface of the brittle substrate. Forming a trench line on the one surface of the brittle substrate by plastic deformation, wherein the trench line is continuously formed in a direction in which the brittle substrate crosses the trench line below the trench line. And d) extending a crack in the brittle substrate in the thickness direction along the trench line. A step of forming a crack line, wherein the crack line disconnects the brittle substrate below the trench line continuously in a direction intersecting with the trench line. Comprising a step of dividing the brittle substrate along a line ,
The tip portion of the cutting edge, the radius of curvature is at 3μm or 40μm or less, the dimension along the axial direction Ru der than 0.5 [mu] m,
A method for cutting brittle substrates. The step c) includes:
c1) a step of sliding the tip of the cutting edge in a first direction;
c2) after the step c1), sliding the tip of the cutting edge in a second direction different from the first direction;
The method for cutting a brittle substrate according to claim 1, comprising:   In the step c), while the tip of the blade is in contact with the one surface of the brittle substrate, the direction of the tip of the blade is not equal to the second direction from the first direction. The method for cutting a brittle substrate according to claim 2, further comprising a step of continuously changing the brittle substrate.   The method for cutting a brittle substrate according to claim 1, wherein in the step (c), the tip of the cutting edge is slid in all directions.   5. The cutting edge according to claim 1, wherein the cutting edge has a right-cone shape having axial symmetry in the axial direction, and the tip of the cutting edge is provided at a vertex of the right-cone shape. 6. Method for dividing a brittle substrate.   The method for cutting a brittle substrate according to any one of claims 1 to 5, wherein the step c) includes a step of rotating the cutting edge around the axial direction.   The step of rotating the cutting edge around the axial direction includes a step of rotating the cutting edge around the axial direction while sliding the tip of the cutting edge on the one surface of the brittle substrate. 7. The method for cutting a brittle substrate according to item 6.   The step of rotating the cutting edge around the axial direction includes a step of rotating the cutting edge around the axial direction without sliding the tip of the cutting edge on the one surface of the brittle substrate. Item 8. The method for cutting a brittle substrate according to Item 6 or 7.   9. The method according to claim 1, wherein the step c) includes a step of supplying a lubricant to a position where the tip of the cutting edge slides on the one surface of the brittle substrate. 9. The method for cutting a brittle substrate according to the above.

Images