JP2018086785A - Scribing wheel and scribing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To scribe a sapphire substrate with a high degree of quality, in a scribing wheel formed of diamond.SOLUTION: A scribing wheel has a cutting edge which has a V-shaped cross-section along a circumferential part, has a ridge line formed in the center, and comprises the ridge line and inclined planes on both the sides of the ridge line. At least a cutting edge part is made of diamond. The scribing wheel is formed as above. In a ridge line part, a groove 15 with a groove length of 9-12 μm, a ridge line length of 5-9 μm and a groove depth of 1.5-4 μm is provided around the entire perimeter. In the case where a thin sapphire substrate is scribed by using the scribing wheel, a cross-section having few crevasses can be obtained even when the thin sapphire substrate is parted.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a scribing wheel and a scribing method for scribing a thin sapphire substrate.

  Conventionally, when a sapphire substrate is scribed and broken, a method is proposed in which a scribe groove is formed by irradiating a sapphire substrate with a laser beam as shown in Patent Documents 1 and 2 and the like, and a break is made along the scribe groove. ing.

  A scribing method using a scribing wheel for cutting glass is also widely used. A conventional scribing wheel uses, as a base material, a disc made of cemented carbide or polycrystalline sintered diamond (hereinafter referred to as PCD) as disclosed in Patent Document 3 and the like. PCD is obtained by sintering diamond particles together with cobalt or the like. The scribing wheel is formed by cutting the circumferential edges obliquely from both sides of a disk as a base material to form a V-shaped cutting edge on the circumferential surface. The scribing wheel formed in this way is rotatably attached to a scribing head of a scribing device, pressed against the brittle material substrate with a predetermined load, and moved along the surface of the brittle material substrate to roll it. You can scribe while.

JP 2012-106279 A JP 2013-51298 A International Publication WO2003 / 51784

  However, the conventional scribing method using laser light has a problem that the surface of the sapphire substrate is easily damaged and the quality of the substrate is impaired. Further, the scribing method using the scribing wheel has a problem that when the thickness of the sapphire substrate is reduced, an irregular crack called a crevasse is likely to occur in the cross section after breaking.

  The present invention has been made in view of such problems, and an object thereof is to provide a scribing wheel suitable for scribing a sapphire substrate and a scribing method thereof.

  In order to solve this problem, the scribing wheel of the present invention has a cutting edge formed of a V-shaped cross section along the circumferential portion and a ridge line formed in the center, and the ridge line and inclined surfaces on both sides of the ridge line, A scribing wheel in which at least the cutting edge portion is formed of diamond, and has grooves formed at predetermined intervals on the entire circumference of the ridge line portion, and the length of the groove is 9 μm or more and 12 μm or less, and the ridge line between the grooves The length is 5 μm or more and 9 μm or less, and the depth of the groove is 1.5 μm or more and 4 μm or less.

  Here, the ratio of the groove length to the ridge line length may be made larger than 1.0.

  In order to solve this problem, the scribing method of the present invention is a scribing method using a scribing wheel, which presses the scribing wheel against a sapphire substrate and rolls the scribing wheel.

  According to the present invention having such characteristics, at least the cutting edge portion of the scribing wheel is made of diamond, and a predetermined groove is formed in the ridge line portion. By scribing the sapphire substrate using the scribing wheel having such a shape, it is possible to generate a vertical crack having a sufficient depth and to suppress the generation of a crevasse after division.

FIG. 1 is a front view and a side view of a scribing wheel according to an embodiment of the present invention. FIG. 2 is an enlarged view of a ridge line portion of the cutting edge according to the present embodiment. FIG. 3 is a diagram showing dimensions of scribing wheels according to Examples 1 to 7 and Comparative Examples 1 to 4 of the present invention. FIG. 4 is a diagram showing the evaluation after scribing using the scribing wheel according to Examples 1 to 7 and Comparative Examples 1 to 4, and after breaking. FIG. 5 is a schematic view showing a state in which a sapphire substrate on which a scribe line is formed is viewed. FIG. 6A is a diagram showing a case where a horizontal crack is not generated in the scribe line in the sapphire substrate on which the scribe line is formed. FIG. 6B is a diagram showing a case where a horizontal crack is generated in the scribe line on the sapphire substrate on which the scribe line is formed. FIG. 7A is a diagram showing a state of a cross section broken along a scribe line, and shows a state without a crevasse. FIG. 7B is a diagram showing a state of a cross section broken along a scribe line, and shows a state where there is a slight crevasse. FIG. 7C is a diagram showing a state of a cross section broken along a scribe line, and shows a state where there are many crevasses.

  FIG. 1 is a front view and a side view of a scribing wheel according to an embodiment of the present invention. When manufacturing a scribing wheel, for example, first, a through hole 12 serving as a shaft hole is formed in the center of a disk 11 serving as a scribing wheel base material such as cemented carbide as shown in FIG. Next, a shaft such as a motor (not shown) is connected to the through hole 12 to rotate the central axis of the through hole 12 as the rotation shaft 12a, and the entire circumference of the disk 11 is connected to the rotation shaft 12a from both sides of the disk. On the other hand, as shown in FIG. 1 (b), the ridgeline and the inclined surfaces on both sides of the ridgeline are formed in a V-shaped vertical section by polishing obliquely. The V-shaped slope formed in this way is defined as a polishing surface 13.

  First, the V-shaped polished surface 13 is roughened in advance so that the diamond film can be easily attached. Next, after forming diamond as a core having a particle size of submicron or less on the slope portion, a diamond thin film is grown by chemical vapor deposition. In this way, the diamond film 14 having a film thickness of, for example, 20 to 30 μm is formed on the polished surface of the V-shaped slope of the scribing wheel by chemical vapor deposition (CVD).

  Next, the tip of the diamond film is polished to form a polished region including a ridgeline. Subsequently, minute grooves are formed at regular intervals in the ridge line portion of the polishing region of the diamond film. Details of the groove will be described with reference to FIG. FIG. 2 is an enlarged view of the ridge line portion of the cutting edge indicated by the alternate long and short dash line S in FIG. 1. As shown in this figure, the length of the ridge line between the groove and the ridge line portion where the polishing surface of the scribing wheel intersects is constant. The groove 15 to be formed is formed on the entire circumference. The groove may be formed by partially removing the cutting edge of a scribing wheel having a diamond film by laser processing. Here, the length A of each groove 15 is preferably 9 μm or more and 12 μm or less. Further, the depth B of the groove is preferably 1.5 μm or more and 4 μm or less, more preferably 2 μm or more and 3 μm or less. The length C of the ridge line is preferably 5 μm or more and 9 μm or less, more preferably 5 μm or more and 7 μm or less. The ratio A / C between the groove length A and the ridgeline length C is preferably greater than 1, more preferably 1.4 or more. If scribing is performed using a scribing wheel in which such grooves are formed all around, suitable scribing can be performed. And when it breaks along this scribe line, a cross section with few crevasses can be obtained.

  In this embodiment, the grooves are formed by laser processing. However, instead of laser processing, the diamond film may be formed by electric discharge machining, or the grooves may be formed by polishing. .

  Alternatively, a scribing wheel may be formed by forming a groove in a V-shaped cutting edge portion of a scribing wheel base material, and coating and polishing the scribing wheel base material with a diamond film by a CVD method.

  Further, in this embodiment, the scribing wheel base material is coated with a diamond film and polished, but the scribing wheel base material itself is made of a diamond material such as single crystal diamond or polycrystalline diamond not containing a binder. It may be.

  Next, an embodiment will be described with reference to FIG. In FIG. 3, the scribing wheels according to Examples 1 to 7 are prepared based on the above-described embodiment. Here, as shown in FIG. 3, the groove length A is 9 or 12 μm, the groove depth B is 1.5, 2, 3, or 4 μm, the ridge line length C is 6 or 8.5 μm, and the edge angle The scribing wheel which set D as 115 degrees is set as Examples 1-7. The groove ridge line ratio A / C was 1.06 to 2.00. At the same time, as Comparative Examples 1 to 4, the groove length A was 6, 9 or 12 μm, the groove depth B was 3 μm, the ridge line length C was 6, 8.5 or 12 μm, and the edge angle D was A scribing wheel at 115 ° was created. The groove ridge line ratio A / C of Comparative Examples 1 to 4 was 0.71 to 1.00.

  Then, using the scribing wheel of each of Examples 1 to 7 and the scribing wheel of Comparative Examples 1 to 4, the scribe load was changed from 1.20 N to 2.22 N, and the sapphire substrate having a thickness of 0.1 mm was pushed. Scribing by rolling and rolling. Furthermore, this sapphire substrate was cut along a scribe line. FIG. 4 is a table showing the results of evaluating the scribe state in three stages and the cross-sectional state in two stages. When evaluating the scribe line, illumination was applied to the sapphire substrate 21 on which a large number of scribe lines were formed in parallel as shown in FIG. 5, and the scribe lines were visually confirmed. Here, when the scribing is good “◯” and “×”, it indicates a state of medium penetration where the scribe line shines evenly as a whole. In addition, “Δ” is thin and shining, but is broken in some places, and indicates that the scribe has low penetration. FIG. 6A shows the quality of the scribe line, showing a state in which there is no horizontal crack in medium penetration (◯) or low penetration (Δ), and FIG. 6B shows a state in which horizontal crack is generated (×). . In FIG. 6B, a horizontal crack is generated on the side of the scribe line.

  Next, the sapphire substrate 21 on which such a scribe line was formed was broken using a breaking device. As for the cross-section, those having no crevasse as shown in FIG. 7A and those having a short crevasse as shown in FIG. 7B and almost no crevice are good (◯), and exceed half the thickness of the substrate as shown in FIG. 7C. A large number of large crevasses were evaluated as bad (x). From these results, it is preferable that the groove length A is 9 to 12 μm and the ridge line length C is 5 to 9 μm as shown in the figure. By properly selecting the scribe load, a good scribe line and cross section can be obtained. Can be obtained. In particular, in Examples 1 and 2, good scribe lines and cross sections could be obtained at a plurality of loads. The same tendency is obtained when the blade edge angle D is 110 to 125 °.

  The scribing wheel of the present invention can provide a scribing wheel for a sapphire substrate that can cut the sapphire substrate with a cross section having almost no crevasse, and can be suitably used for a scribing apparatus.

DESCRIPTION OF SYMBOLS 10 Scribing wheel 11 Disc 12 Through-hole 13 Polishing surface 14 Diamond film 15 Groove 21 Sapphire substrate

Claims (3)

A scribing wheel having a V-shaped cross section along the circumference, a ridge line formed in the center, a blade edge formed of the ridge line and inclined surfaces on both sides of the ridge line, and at least a blade edge portion formed of diamond,
Grooves formed at predetermined intervals on the entire circumference of the ridge line portion, the length of the groove being 9 μm or more and 12 μm or less, the length of the ridge line between the grooves being 5 μm or more and 9 μm or less, and the depth of the groove being A scribing wheel having a size of 1.5 μm to 4 μm.   The scribing wheel according to claim 1, wherein a ratio of the groove length to the ridge line length is larger than 1.0. A scribing method using the scribing wheel according to claim 1 or 2,
Press the scribing wheel against the sapphire substrate,
A scribing method for scribing by rolling the scribing wheel.