JP6608604B2 - Chamfered substrate and method for manufacturing liquid crystal display device - Google Patents

Description

  The present invention relates to a substrate and a liquid crystal display device in which end surfaces of various materials such as silicon, sapphire, compound, glass, etc., in particular, a plate-like workpiece such as a semiconductor wafer, a cover glass, etc. are chamfered with high accuracy. It is suitable for those having a straight portion other than a circle in the planar shape.

  In recent years, there has been a strong demand for wafer quality improvement, and the processing state of the wafer end face (edge part) has been regarded as important, and semiconductor wafers such as silicon wafers used in the manufacture of semiconductor devices and the like prevent chipping due to handling. A chamfering process is performed by grinding the edge, and a mirror chamfering process is performed by polishing. That is, in the semiconductor manufacturing process, the quality improvement of the edge characteristics is an indispensable process from the wafer manufacturing to the device manufacturing.

  Silicon and other materials are hard and brittle, and if the edge of the wafer remains sharp during slicing, it can easily crack or chip during handling such as transport and alignment in subsequent processing steps, and fragments can damage or contaminate the wafer surface. Or In order to prevent this, the end face of the cut wafer is chamfered with a chamfering grindstone coated with diamond. At this time, the diameter of the outer periphery with variations is matched to match the width of the orientation flat (OF), and the size of a small notch called a notch is also matched.

  In addition, a structure in which a touch sensor glass is sandwiched between a conventional liquid crystal panel and a cover glass has been increasingly integrated with a cover glass. In this case, a large glass substrate was cut into a predetermined cover glass size, then chamfered, and then chemically strengthened, followed by masking printing and sensor electrode formation.

  Further, in normal grinding, the chamfered portion is ground in a state where the main surface of the wafer is perpendicular to the rotation axis of the resin grindstone. In this case, circumferential chamfer marks are likely to be generated in the chamfered portion. Therefore, it is known to perform so-called helical grinding in which a chamfered portion of a wafer is ground by tilting a resin bond grindstone (resin grindstone) with respect to the wafer, for example.

  When the helical grinding is performed, not only the processing distortion of the chamfered portion is reduced as compared with the normal grinding, but also an effect that the contact area between the chamfered portion of the wafer and the grindstone is increased and the surface roughness of the chamfered portion is improved.

  Furthermore, when the chamfered portion of a semiconductor wafer is helically ground with a resin grindstone or the like, if the chamfered portion is continuously processed, the vertical angle of the groove of the resin grindstone gradually changes, resulting in a further vertical asymmetry of the chamfered portion of the wafer. growing. Therefore, the edge of the disc-shaped truer is ground with the groove of the first grindstone formed with the groove of the asymmetrical shape up and down to form the edge of the truer into the asymmetrical groove shape, and the second A groove is formed around the second whetstone by relatively tilting the whetstone, and a wafer is tilted relative to the groove direction by the second whetstone to obtain a substantially symmetrical resin whetstone, and chamfered. It is known to finely grind parts, and is described in Patent Document 1, for example.

  Further, in a chamfering method in which the rotation axis of the chamfering grindstone is inclined at a predetermined angle with respect to the rotation axis of the wafer, it is known to form a wafer outer peripheral portion and a processing groove for the OF portion on the outer peripheral grinding grindstone. It is described in Document 2.

  Furthermore, in order to make the chamfer width of the notch portion constant, it is known that the grindstone is relatively moved in the thickness direction of the wafer during chamfering, and is described in Patent Document 3.

JP 2007-165712 A JP 2007-21586 A JP 2005-153129 A

In the above-described conventional technology, in a smartphone or tablet that has been reduced in thickness and weight, the chamfering process is performed after cutting a large glass substrate into a predetermined cover glass size, and then the method of performing chemical strengthening is cut. Each glass substrate must be chemically strengthened and the next step, printing and sensor electrode formation, must be performed, and production efficiency must be significantly reduced. However, by masking and printing on a large glass substrate that has been chemically strengthened to form a sensor electrode, and then cutting and chamfering, the chamfering quality, surface roughness, and generation of microcracks are the glass substrate. This has a direct effect on the strength of the end face of the steel and is difficult to perform with normal chamfering.
Moreover, in the thing of patent document 1, the 1st grindstone in which the groove | channel of the asymmetrical shape of an up-down direction was formed is required, and the determination of the shape is difficult. In the case of a circular wafer, the same shape can be used for the entire circumference, so it can be determined uniquely, but it can be determined by using a wafer substrate with an OF, a rectangular or polygonal wafer with an arc at a corner, a substrate, a cover glass, etc. If there is a part and a non-circular part, it is not only more difficult, but also the change in the vertical angle of the groove of the resin grindstone becomes larger at the position where it moves from the circular part to the non-circular part, and the entire circumference is helically ground. It was extremely difficult to do. In other words, at the corner portion of the substrate (work) having a corner, one-side contact with only one of the upper surface and the lower surface of the grindstone groove occurred, and good chamfering could not be performed.

  The one described in Patent Document 2 is good when the grinding process is complicated and the main part is a circular part and the number of non-circular parts is small, but application is difficult in the case of a rectangle or a polygon.

  In the thing of patent document 3, since it must carry out, moving a grindstone relatively in the thickness direction of a wafer during chamfering, in order to raise the accuracy of chamfering, control of the thickness direction of a wafer or a grindstone is required. It was complicated and difficult.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to easily perform helical grinding of end faces and chamfered slopes even with rectangular or polygonal wafers, substrates, cover glasses and the like having circular and non-circular portions. It is to realize end chamfering after chemical strengthening by improving end face strength, reducing shape collapse and generation of microcracks.

In order to achieve the above object, the present invention provides a substrate manufacturing method in which a planar shape is rectangular, and the end surface is chamfered with a grinding groove formed on a grinding wheel. The central portion in the thickness direction is helically ground at 3 to 15 °, and the upper and lower portions of the end face are helically ground at a chamfer angle.

In the above, it is desirable that the chemical strengthening process is performed on the large substrate, then the substrate is cut into a predetermined shape and the helical grinding is performed.

Further, in the above, the upper part of the end face is ground by the upper surface slope of the grinding groove , and then the substrate is lowered relative to the grinding wheel in the thickness direction and again ground.
Alternatively, it is desirable to grind the lower part of the end face with the lower slope of the grinding groove , and then raise the substrate relative to the grinding wheel in the thickness direction and grind again .

Further, in the above, the upper or lower portion of the end face is ground so as to make one round with the grinding groove over the entire circumference, and then the substrate is lowered relative to the grinding wheel in the thickness direction or It is desirable to raise and grind one more round .

Further, in the above, it is preferable that the processing of the end face is performed by grinding the upper part of the end face, grinding the central part, and grinding the lower part, respectively .

Further, in the above, it is preferable that the upper grinding, the central grinding, and the lower grinding are performed so that each of the end faces makes one round with the grinding groove over the entire circumference .

Further, in the above, it is desirable that the substrate is subjected to masking printing and sensor electrode formation on the plane .

The present invention also provides a method for manufacturing a liquid crystal display device comprising a cover glass having a rectangular planar shape, chamfered with a grinding groove formed on a grinding wheel, and a touch sensor incorporated in the liquid crystal panel. Then, the cover glass is helically ground at a central portion in the thickness direction of the end face at 3 to 15 ° over the entire circumference, and the upper and lower portions are helically ground at a chamfer angle.

  According to the present invention, the substrate has a rectangular planar shape, and the central portion in the thickness direction of the end surface is helically ground at 3 to 15 ° over the entire circumference, and the upper and lower portions of the end surface are chamfered. Since it is helically ground at an angle, even if it is a rectangular or polygonal workpiece, the surface roughness can be improved and the shape collapse can be reduced. As a result, the end face strength of the glass substrate is improved, and it is possible to perform cutting and chamfering after chemical strengthening, thereby improving the production efficiency of an in-cell type liquid crystal display device and the like.

The top view which shows the principal part of the chamfering apparatus which concerns on one Embodiment of this invention. The perspective view which shows the structure of the process part in one Embodiment. (Work material is circular and straight part) The top view in FIG. The perspective view which shows the structure of the process part in one Embodiment. (Work material is mainly straight part) The top view in FIG. The side view which shows the relationship between the grinding groove | channel and workpiece in one Embodiment. (Top surface processing) The side view which shows the relationship between the grinding groove | channel and workpiece in one Embodiment. (Processing of the bottom surface) The top view explaining contact | abutting with a workpiece and the upper-lower-end part of a grinding wheel. The perspective view which shows the helical grinding of the end surface processing of the conventional board | plate material. The side view explaining the difference between the conventional grinding and grinding by one embodiment. The side view which shows the end surface of the workpiece processed by the chamfering method by one Embodiment. The side view which shows the procedure of the chamfering method by other embodiment. The side view which shows the detail of the grinding wheel and workpiece which concern on embodiment of this invention. Sectional drawing which shows the basic structure of the touchscreen which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The invention is not limited to the embodiments, and constituent elements in the embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  FIG. 1 is a plan view showing a main part of a chamfering apparatus according to an embodiment of the present invention. The chamfering apparatus mainly includes a supply / recovery unit 20 and a processing unit 10, and includes a pre-alignment unit, a cleaning unit, a post-measurement unit, a transport unit, and the like, although not shown.

  The wafer processing step is performed in the order of slicing → chamfering → lapping → etching → donor killer → fine chamfering, and various cleanings are used to remove dirt between the processes. Silicon and other materials are hard and brittle, and if the edge of the wafer remains sharp during slicing, it can easily crack or chip during handling such as transport and alignment in subsequent processing steps, and fragments can damage or contaminate the wafer surface. Or In order to prevent this, in the chamfering process, the end surface of the cut wafer is chamfered with a chamfering grindstone coated with diamond.

  The chamfering process may be performed after the lapping process. At this time, the diameter of the outer periphery with variations is matched to match the width of the orientation flat (OF), and the size of a small notch called a notch is also matched.

  The supply / recovery unit 20 supplies the wafer W to be chamfered from the wafer cassette 30 to the processing unit 10 and collects the chamfered wafer to the wafer cassette 30. This operation is performed by the supply / recovery robot 40. The wafer cassette 30 is set on a cassette table 31 and stores a large number of wafers W to be chamfered. The supply / recovery robot 40 takes out the wafers W one by one from the wafer cassette 30 and stores the chamfered wafers in the wafer cassette 30.

  The supply / recovery robot 40 includes a three-axis rotation type transfer arm 50, and the transfer arm 50 includes a suction pad (not shown) on an upper surface thereof. The transfer arm 40 holds the wafer W by vacuum-sucking the back surface of the wafer W with a suction pad. That is, the transfer arm 50 of the supply / recovery robot 40 can move up and down, move up and down, and turn while holding the wafer W, and the wafer W is transferred by combining these operations.

  The processing unit 10 is disposed in the front portion of the wafer chamfering apparatus, and performs all processing of the outer peripheral chamfering of the wafer W, that is, roughing to finishing. The processing unit 10 includes a wafer feeding device 60, an outer periphery rough grinding device 62, a transfer arm 63 that conveys the wafer W, and an outer periphery fine grinding device 61.

  FIG. 2 is a perspective view showing the configuration of the processing unit 10, FIG. 3 is a plan view, and the wafer feeding device 60 has a chuck table (wafer table) 66 that holds the wafer W by suction. The chuck table 66 is driven by driving means (not shown) to move in the front-rear direction (Y-axis direction), the left-right direction (X-axis direction), and the vertical direction (Z-axis direction). By being driven by the table drive motor 65, it rotates around the central axis (θ axis).

  The outer peripheral rough grinding device 62 is disposed at a position separated from the chuck table 66 of the wafer feeding device 60 by a predetermined distance in the Y-axis direction. This outer peripheral rough grinding device 62 has an outer peripheral rough grinding spindle 68 that is driven by an outer peripheral rough grinding motor 67 to rotate. The outer periphery roughing spindle 68 is configured to be movable in the front-rear direction (Y-axis direction) and the vertical direction (Z-axis direction) by being driven by a driving unit (not shown).

  A peripheral rough grinding spindle 69 for roughing (rough grinding) the outer periphery of the wafer W is mounted on the peripheral rough grinding spindle 68, and serves as a rotation axis thereof. The outer peripheral rough grinding wheel 69 has a plurality of outer peripheral rough grinding grooves formed on the outer peripheral surface thereof (general shape grindstone). By pressing the outer periphery of the wafer W against this groove, the outer periphery of the wafer W is roughened ( Rough grinding).

  The peripheral grinding device 61 is disposed at a position away from the chuck table 66 of the wafer feeding device 60 by a predetermined distance in the X-axis direction. The outer peripheral fine grinding device 61 has an outer peripheral fine grinding spindle 71 that is driven by the outer peripheral fine grinding motor 70 to rotate. The outer peripheral precision spindle 71 is configured to be movable in the left and right direction (X-axis direction) and the vertical direction (Z-axis direction) by being driven by a driving means (not shown). The outer peripheral fine grinding spindle 71 is equipped with an outer peripheral fine grinding wheel 72 for finishing the outer periphery of the wafer W (fine grinding), and serves as a rotating shaft thereof.

  The peripheral grinding wheel 72 has a circumferential grinding groove formed on its outer peripheral surface (total grinding wheel), and the outer circumference of the wafer W is finished by pressing the outer circumference of the wafer W against this groove.

  At this time, the wafer is subjected to helical grinding performed by tilting the rotation axis of the outer peripheral fine spindle 71 with respect to the rotation axis of the chuck table 66 in the tangential direction of the outer periphery of the wafer W by 3 to 15 °, preferably 6 to 10 °. Finish the outer chamfering of W.

  As a result, the movement direction of the abrasive grains intersects with the movement direction of the outer periphery of the wafer W, the contact area increases, etc., so that the wear of the grinding wheel is suppressed and the shape deformation of the outer periphery can be reduced. As a result, the roughness of the processed surface (grind surface) is improved.

  Next, the operation of the processing unit 10 will be described. In the standby state before the start of processing, the wafer W held on the chuck table 66 is arranged so that the center thereof coincides with the rotation axis of the chuck table 66. At this time, the OF portion of the wafer W is disposed so as to face a predetermined direction (in this example, the Y-axis direction).

  Further, the outer peripheral rough grinding wheel 69 and the outer peripheral fine grinding wheel 72 are located at positions away from the wafer W by a predetermined distance. Specifically, the rotation center of the outer peripheral rough grinding wheel 69 is disposed at a position separated from the rotation center of the wafer W by a predetermined distance in the Y-axis direction, and the rotation center of the outer peripheral grinding wheel 72 is relative to the wafer W. It is arranged at a position separated by a predetermined distance in the X-axis direction.

  First, an alignment operation is performed. In this alignment operation, the relative positional relationship between the wafer W held on the chuck table 66, the outer peripheral rough grinding wheel 69, and the outer peripheral fine grinding wheel 72 in the vertical direction (Z-axis direction) is adjusted.

  When the alignment operation is completed, the outer periphery roughing motor 69 is driven. Next, grinding (rough machining) by the outer periphery rough grinding wheel 69 is started. Specifically, a Y-axis motor (not shown) of the outer peripheral rough grinding device 62 is driven, and the outer peripheral rough grinding spindle 68 is fed toward the chuck table 66 along the Y-axis direction.

  As the outer peripheral rough grinding grindstone 69, for example, a diamond bond metal bond grindstone having a diameter of 202 mm and having a particle size of # 800 can be used. The outer peripheral grinding wheel spindle 68 is a built-in motor driven spindle using a ball bearing and is rotated at a predetermined rotational speed, for example, a rotational speed of 8,000 rpm.

  When the outer periphery roughing spindle 68 is fed toward the chuck table 66, the outer periphery of the wafer W comes into contact with the outer peripheral rough grinding grinding groove formed on the outer peripheral rough grinding wheel 69, and the outer periphery of the wafer W is outer peripheral rough grinding. After being ground by the grindstone 69, rough machining of the outer peripheral chamfer of the wafer W is started.

  Since the wafer W in FIG. 2 is initially circular after the rough machining by the outer peripheral rough grinding wheel 69 is started, the wafer W held on the chuck table 66 starts to rotate in the arrow direction at a constant speed. When this rotational angle, that is, the OF portion where the machining point is a straight line portion, the feed amount in the direction toward the chuck table 66 in the Y direction is increased, and the outer periphery spindle 68 is moved in the X direction. Move the straight line in the direction to process the straight part. Thereafter, when the processing of the linear portion is finished, the plate-like wafer W held on the chuck table 66 is rotated again in the direction of the arrow at a constant speed, the remaining circular portion is ground, and rough processing by the outer peripheral rough grinding wheel 69 is performed. Exit.

  Next, the finishing process by the outer peripheral grinding wheel 72 is performed in the same manner. As the outer peripheral grinding wheel 72, a resin bond grinding wheel of diamond abrasive grains is suitable. Further, the outer peripheral chamfering of the wafer W is performed with the rotation axis of the outer peripheral fine spindle 72 inclined to the tangential direction of the outer periphery of the wafer W with respect to the rotation axis of the chuck table 66 by 3 to 15 °, preferably 6 to 10 °. Finishing is performed.

  Furthermore, the chamfering groove of the outer peripheral grinding wheel 72 is formed by a truer, but detailed description thereof is omitted. Further, as the outer peripheral rough grinding grindstone 69, for example, a material which is mainly composed of metal powder such as Fe, Cr, Cu or the like and mixed with diamond abrasive grains is used. As the material of the truer, a material which can be processed by the outer peripheral rough grinding wheel 69 and can grind the outer peripheral grinding wheel 72 is adopted.

  For example, it is desirable that abrasive grains made of silicon carbide be bonded with a phenol resin with a filler or the like if necessary, and molded into a disk-shaped truer. As the material of the outer peripheral fine grinding stone 72, a material capable of finely grinding a chamfered portion such as a silicon wafer by the formed polishing while the grinding groove 74 can be formed around by grinding with a truer. For example, it is desirable to use a material mainly composed of phenol resin, epoxy resin, polyimide resin, polystyrene resin or polyethylene resin, and formed by mixing diamond abrasive grains or cubic boron nitride abrasive grains.

  Further, as the peripheral fine grinding stone 72, for example, a resin bond grindstone of diamond abrasive grains having a diameter of 50 mm and having a grain size of # 3000 is used. The outer peripheral precision spindle 71 is a built-in motor driven spindle using an air bearing and is rotated at a rotational speed of 35,000 rpm.

  FIG. 4 is a perspective view showing a configuration of a processing portion when the workpiece is not circular but rectangular, and FIG. 5 is a plan view similarly. When the workpiece is not a circle but a rectangle, as shown in FIGS.

  As smartphones and tablets become thinner and lighter, glass substrates, cover glass, sapphire, and ceramics are used on the surface, and end face strength is important. In mirror grinding, chipping suppression and good surface roughness are achieved. Is required. Chamfering processing quality, processing surface roughness, microcracking, etc. directly affect the end face strength of the glass substrate.

  4 and 5 show chamfering processing of a rectangular cover glass in a smartphone or tablet, and a structure in which a touch sensor is integrated with a cover glass, masking printing on a glass substrate, forming a sensor electrode, and then cutting, Chamfering is performed. Then, the chamfering is started by driving a Y axis motor (not shown) of the outer peripheral grinding device 61 and feeding the outer peripheral spindle 71 toward the chuck table 73 along the Y axis direction.

  When the outer periphery precision spindle 71 is fed toward the chuck table 73, the straight portion of the cover glass (or wafer) W comes into contact with the outer periphery fine grinding groove, which is a chamfering groove formed on the outer periphery fine grinding wheel 72. Then, the outer peripheral portion of the cover glass W is helically ground by the outer peripheral fine grinding stone 72, and the processing of the outer peripheral chamfering of the cover glass W is started. After the processing by the peripheral grinding wheel 72 is started, the cover glass W in FIGS. 4 and 5 is rectangular, and therefore the cover glass W held on the chuck table 73 starts moving at a constant speed in the X-axis direction. When the processing point reaches the corner, the chuck table 73 is rotated by 90 °, and linear movement is started in the X-axis direction to process the next linear portion. Thereafter, the entire outer periphery of the cover glass W is processed similarly.

  Also, the grinding wheel is supplied with a saturated fatty acid solution and a lubricant to a chamfering wheel material having a porous surface, and the surface is dried to form a lubricant-impregnated grinding wheel. The grinding wheel containing this lubricant is cooled with water during grinding and used. It is desirable to do. Thereby, the lubricant can be reliably supplied to the cutting point of the grindstone, and the cutting point temperature can be set to a predetermined temperature or lower. Moreover, since the coolant is water, it is possible to prevent environmental pollution due to the coolant. Furthermore, in the wafer chamfering apparatus, since the grindstone is impregnated with the lubricant, the lubricant can be supplied to the cutting point over a long period of time, and the coolant is water, so that processing can be performed at low temperature and in consideration of the environment.

  The chuck table 73 has the same shape as that of the rectangular cover glass W as shown in FIG. 5, but the chuck table 73 is more elastic than the cover glass W so that the cover glass W itself is slightly elastically deformed when processed by the outer peripheral grinding wheel 72. The cover glass W is held sufficiently in an overhanging manner from the chuck table 73.

  Specifically, the size of the chuck table 73 is Q = (1) where Q is the distance from the center of the cover glass W in the X-axis direction and P is the distance from the center of the chuck table 73 in the X-axis direction. .3 to 1.7) P, more preferably, Q = 1.5P is preferable from the viewpoint of fixing and grinding by adsorption of the cover glass W. That is, while avoiding the influence on the processing accuracy such as deformation, bending, and distortion of the cover glass W, the workpiece, the cover glass W itself is slightly elastically deformed during processing, and the outer peripheral grinding wheel 72 is a soft resin bond wheel. Combined with this, it reduces the impact of such vibration. The same applies to the Y-axis direction, and it is desirable to set N = (1.3 to 1.7) H in FIG. 5, more preferably N = 1.5H. That is, the shape of the chuck table 73 is smaller than the outer peripheral shape of the workpiece, and is preferably 0.6 to 0.8 times larger than the planar shape of the cover glass W in both length and width. The rectangular cover glass W is preferably about 80 mm × 40 mm in the rectangular chuck table 73 when the length × width is about 120 mm × 60 mm and the thickness is about 0.5 to 1.5 mm.

  Since the rotation axis of the outer peripheral fine spindle 72 is inclined with respect to the chuck table 73 in the tangential direction of the outer periphery of the cover glass W by θ = 3 to 15 °, preferably 6 to 10 °, the cover glass W is precisely polished on the outer periphery. The grindstone 72 contacts the grinding groove 74 at this angle θ, and the movement direction of the abrasive grains intersects the movement direction of the cover glass W. Further, if the inclination angle is too large, it is not preferable in terms of increase in grinding resistance, chipping of upper and lower corners on the end face, scratches, and the like.

  FIG. 6 is a side view showing the relationship between the grinding groove 74 of the peripheral grinding wheel 72 and the workpiece W. As shown in FIG. When the grinding groove 74 of the grinding wheel 72 is inclined at an angle θ, the lower surface of the workpiece W comes closest to the lower end of the grinding groove 74 from the position where the upper end of the grinding groove 74 contacts the upper surface of the workpiece W. The distance to the non-contact position, that is, the apparent thickness of the workpiece W when the grinding groove 74 is inclined by the angle θ, is larger than the dimension y0 from the right end to the left end in FIG. 6, and y> y0. . y0 is approximately Dtan θ + t / cos θ, where D is the diameter of the grinding groove 74 and t is the thickness of the workpiece W. The method of widening the width of the grinding groove 74 may be to widen the transfer groove when tooling in advance, or the grinding groove 74 may be processed widely by moving the tooling tool up and down in the Z-axis direction. May be.

Next, the processing procedure of helical grinding will be described below.
FIG. 6 is a side view showing a state in which the upper surface of the cover glass W is being processed. When the outer peripheral precision spindle 71 is fed toward the chuck table 73, the upper surface slope 72u at the upper right end portion of the grinding groove 74 is shown. The upper surface of the cover glass W, the upper right end portion in FIG. 6 abuts, starts processing, and then the cover glass W held on the chuck table 73 moves at a constant speed in the X-axis direction to perform chamfering.

  Since the grinding groove 74 is wider than the apparent thickness of the cover glass W, the lower surface of the cover glass W does not contact. The central part and the main part of the cover glass W in the thickness direction are helically ground by contacting the circumferential part of the grinding groove 74 of the outer peripheral fine grinding stone 72. When the processing point reaches the corner R of the cover glass W, the chuck table 73 rotates to process the corner R. At this time, it becomes the same as grinding of the circular portion, and the contact area becomes small. Therefore, the contact of the upper surface slope of the grinding groove 74 becomes weak, and the central portion in the thickness direction is mainly ground. Hereinafter, similarly, the cover glass W is processed until it goes around once.

  FIG. 7 is a side view showing a state in which the lower surface of the cover glass W is being processed. At the point where the above processing is performed once, the outer peripheral grinding wheel 72 is raised in the Z-axis direction from the state of FIG. The table 73 is lowered in the Z-axis direction so that the lower surface slope of the grinding groove 74 is in contact with the lower surface of the cover glass W and the lower surface slope 72d at the lower left end in FIG. That is, the grinding wheel is raised relative to the workpiece in the thickness direction. Thereafter, the cover glass W held on the chuck table 73 moves at a constant speed in the X-axis direction to perform chamfering on the second round.

  Since the grinding groove 74 is wider than the apparent thickness of the cover glass W, the upper surface of the cover glass W does not contact. The central part and the main part of the cover glass W in the thickness direction are helically ground by contacting the circumferential part of the grinding groove 74 of the outer peripheral fine grinding stone 72.

  As described above, the grinding groove 74 of the outer peripheral fine grinding wheel 72 is brought into contact with the cover glass W while being inclined at an angle θ so that the movement direction of the abrasive grains intersects the movement direction of the cover glass W, and The width of the grinding groove 74 of the outer peripheral grinding wheel 72 is made wider than the apparent thickness of the workpiece when the outer circumferential grinding wheel 72 is tilted at an angle θ with respect to the workpiece. By moving up and down in the axial direction, helical grinding can be applied to chamfering of a linear portion such as OF or a material such as a rectangle or a polygon. Thereby, the surface roughness and processing distortion of the end face can be reduced, and even a high-quality grindstone can be used for a long time.

  Here, the inventor increases the angle θ in FIG. 6 so that the upper right end portion of the upper surface of the cover glass W comes into contact with the upper surface inclined surface 72u, and the lower surface inclined surface is in contact with the lower left end portion of the lower surface of the cover glass W. An evaluation was performed in which grinding was performed so that 72d abuts. Then, when grinding the corners of the cover glass W, it has been found that there is always a situation where the cover glass W can contact only one of the upper surface slope 72u and the lower surface slope 72d. For this reason, in the corner | angular part of the cover glass W, it turned out that the part which grinding | polishing is not enough in either the upper surface or the lower surface generate | occur | produces.

  Therefore, when the present inventor performs helical polishing, the relationship between θ, y, and the thickness t of the cover glass W in FIG. 6 is “only one of the upper surface or the lower surface of the cover glass W is the grinding groove 74. It has been found that θ, y, and t must be selected so as to contact one end (upper surface inclined surface 72u or lower surface inclined surface 72d) and the other does not contact the end portion (condition 1). Therefore, if any of these parameters is determined, the above condition 1 must be satisfied by adjusting the changeable parameters. At this time, it was found that it is preferable that y0 in FIG. This is because most of the grinding groove 74 can be used, so that the life of the grindstone is extended.

  FIG. 8 is a plan view for explaining the difference in contact between the outer peripheral precision grinding wheel 72 and the grinding groove 74 at the upper and lower ends in the thickness direction of the cover glass W between the processing of the circular portion and the processing of the straight portion. The contact area between the cylindrical portion of the grinding groove 74 of the fine grinding wheel 72 and the linear workpiece W1 is not only larger than the contact area between the cylindrical portion and the circular workpiece W2, but also the upper surface slope 72u or the lower surface slope 72d at the upper and lower ends of the grinding groove 74. The contact area L of the straight workpiece W1 is larger than the contact area M of the circular workpiece W2.

  Therefore, not only the grinding resistance of the linear workpiece W1 is larger than the grinding resistance of the circular workpiece W2, but also the chamfering of the linear workpiece W1 can be performed by chamfering the width in the thickness direction of the grinding groove 74 to the circular workpiece W2. become unable. Even if the grinding groove 74 is formed so that the chamfering can be performed symmetrically with respect to the circular workpiece W2, if the chamfering is performed on the straight workpiece W1, the shapes of the upper and lower surfaces are different.

  FIG. 9 shows an example of helical grinding by an axis inclination method in which one axis is added to the surface grinder 80 in contrast to the conventional end face processing of a plate material. As shown in FIG. 9, the precision stage 81 is arranged at an inclination angle α so that the workpiece 83 passes through the lowest point of the grindstone 82. The grindstone 82 is wider than the workpiece 83, and both surfaces are fixed to the vicinity of the machining surface by the vise 84.

  In this method, as shown in FIG. 10 (a), the grindstone 82 is fixed because the workpiece 83 is firmly fixed by the vise 84, the rotation axis of the grindstone 82 is horizontal with the machining surface, and the like. When pressed as indicated by the arrow V, the wobbling of the grindstone 82 impacts the workpiece 83 and damages the processed surface. Further, since the ground metal falls to the processed surface, scratches and scratches due to the scratch are generated on the processed surface.

  On the other hand, as shown in FIGS. 6 and 7, in the present invention, the grinding groove 74 of the outer peripheral grinding wheel 72 is inclined at an angle θ with respect to the workpiece W. The chuck table 73 is mounted with a flat surface of the cover glass W, and the surface of the chuck table 73 is decompressed by an air compressor, a blower or the like, and the cover glass W is adsorbed and fixed. In the case of FIG. 10B in which the cover glass W overhangs from the chuck table 73 and is sucked and held in the vertical direction, the grinding groove 74 of the outer peripheral grinding wheel 72 comes into contact with the processing surface perpendicularly, The pressing force by the grinding wheel 72 works as shown by an arrow H.

  Therefore, a workpiece, for example, the cover glass W itself is slightly elastically deformed during processing, and coupled with the fact that the outer peripheral fine grinding stone 72 is a soft resin bond grinding stone, the impact such as runout is reduced. Therefore, there is no damage such as scratches on the machined surface, and the ground metal is discharged as shown by the arrow, and it does not fall on the machined surface, causing scratches and scratches on the machined surface. There is no.

  FIG. 11 is a side view showing the end face of the workpiece processed by the above-described chamfering method, and the state of the streak after grinding with the outer peripheral grinding wheel 72 which is a resin grindstone is indicated by oblique lines. The grinding groove 74 has a sufficiently large width with respect to the thickness of the workpiece (substrate, workpiece) and is brought into contact with the workpiece at an oblique angle of 6 to 10 °. Chamfering was performed so that only one side was in contact with the work and not the other side. Actually, grinding with the upper surface abutting was performed once for the entire circumference of the end surface of the workpiece, then the lower surface was abutted, and further one round was performed for a total of two rounds of polishing and chamfering. .

  In conventional chamfering by helical grinding, a workpiece having a corner and a straight part was hit by only one of the upper and lower surfaces of the grinding groove of the grindstone, and good chamfering was not possible. In this way, the central portion C in the thickness direction becomes a characteristic streak of helical grinding according to the angle at which the grindstone is inclined, and the shape is not deformed with good surface roughness.

  In addition, both the upper and lower ends are symmetrical in angle and size. In the figure, the width of the upper chamfered portion Tu and the lower chamfered portion Td is uniform, and the corners of the end surface of the workpiece are helically ground at the ends of the grinding grooves. The streak, the angle, and the direction are different as much as the end of the grinding groove hits, and this clearly appears.

  Furthermore, along with the thinning and weight reduction of smartphones and tablets, conventionally, the glass substrate was cut into a predetermined size and then chemically strengthened, followed by masking printing to form sensor electrodes. . Chemical strengthening is general strengthening by chemical treatment of the glass surface. As a general method, the alkali ions in the glass are replaced with other alkali ions having a larger molecular size. This ion exchange method is performed to generate a compressive stress on the glass surface by ion exchange, and to eliminate the disadvantages of brittle materials that are brittle and easy to break.

  On the other hand, according to the above chamfering process, even after performing chemical strengthening treatment with a large glass substrate, masking printing, forming a sensor electrode, and then performing cutting and chamfering, that is, on the end face Even when not chemically strengthened, good surface roughness can be obtained, and the occurrence of microcracks can be suppressed. As a result, in the production of a two-layer OGS (One Glass Solution) capacitive touch panel in which a touch sensor is integrated with a single cover glass, production efficiency is extremely improved, which is practically sufficient. End face strength can be obtained.

  Further, FIG. 14 is a cross-sectional view showing a basic structure of a liquid crystal display device provided with a capacitive touch panel having a two-layer structure. A sensor electrode of the touch sensor 102 is formed under the cover glass W, and the liquid crystal display 104 The touch sensor 102 is incorporated in a liquid crystal panel, that is, a so-called in-cell type liquid crystal display device.

  Furthermore, not only the surface roughness and shape symmetry, but also after the grinding groove is corrected once (tooling), it continues until the grinding ability decreases, the predetermined outer peripheral surface width, outer peripheral angle, and outer peripheral shape are not satisfied. The number of sheets that can be processed can be increased. Further, when the chamfering process is repeated by repeating the tooling of the outer peripheral grinding wheel 72 which is a resin grindstone, the number of sheets that can be machined before the resin grindstone becomes smaller than a predetermined diameter due to wear and becomes unusable is increased. be able to.

  As described above, in FIGS. 6 and 7, the helical grinding using the outer peripheral fine grinding wheel 72 has been described. However, during the rough grinding, that is, when the outer peripheral coarse grinding wheel 69 is used, the helical grinding that makes two rounds may be performed similarly. . According to this, at the time of fine grinding, it is possible to prevent wear and clogging of the grinding groove 74 of the outer peripheral precision grinding wheel 72 and to prevent deformation of the groove shape, and to perform better chamfering.

  Further, the upper part of the end surface of the workpiece is ground so as to make one round with the grinding groove 74 over the entire circumference (upper grinding), and then the grinding wheel 69 or 72 is relatively relative to the thickness direction of the workpiece. In this case, the lower part is ground once (lower part grinding), but this order may be reversed, and the upper surface slope which is the end part of the grinding groove 74 at the upper part and the lower part of the end face of the workpiece. You may grind separately the center part which neither 72u nor the lower surface inclined surface 72d touches.

  FIG. 12 shows center grinding (a), upper grinding (b), and lower grinding (c). In the central grinding (a), when the chuck table 73 is fed toward the outer peripheral precision spindle 71, the upper surface slope 72u at the upper right end portion and the lower surface slope 72d at the lower left end portion of the grinding groove 74 are both cover glass. Machining is started without contacting the upper and lower surfaces of W, and then the cover glass W held on the chuck table 73 is moved at a constant speed in the Y-axis direction to perform chamfering. When the grinding groove 74 has an apparent thickness of the cover glass W, and when the grinding groove 74 of the outer peripheral grinding wheel 72 is tilted at an angle θ, the thickness of the grinding groove 74 is considered in consideration of both the diameter D and the thickness t of the cover glass W. More than at least 20-30% wider.

  The central part and the main part of the cover glass W in the thickness direction are helically ground by contacting the circumferential part of the grinding groove 74 of the outer peripheral fine grinding stone 72. When the processing point reaches the corner R, the chuck table 73 is rotated to process the corner R. Since the end portion in the thickness direction of the cover glass W is not ground by the upper and lower slopes (or upper and lower end portions) of the grinding groove 74, it is suitable for processing regardless of the outer peripheral shape of the cover glass W without affecting the vertical asymmetry. It is convenient to cut out the shape when the circular part as shown in 2 is the main part and there is a straight part such as the OF part.

    FIG. 12B shows the upper grinding. From the state of FIG. 12A, the outer peripheral grinding wheel 72 is lowered in the Z-axis direction or the chuck table 73 is raised in the Z-axis direction, and the upper right end of the grinding groove 74 is shown. The upper surface of the cover glass W, the upper right end in the figure, is brought into contact with the upper surface slope 72u of the portion. That is, the grinding wheel is lowered relative to the workpiece in the thickness direction. Thereafter, the cover glass W held on the chuck table 73 is moved at a constant speed in the Y-axis direction, and chamfering is performed by helical grinding.

  FIG. 12C shows the grinding of the lower part. From the state of FIG. 12B, the outer peripheral grinding wheel 72 is raised in the Z-axis direction or the chuck table 73 is lowered in the Z-axis direction, and the lower surface slope of the grinding groove 74 Is in contact with the lower surface of the cover glass W, that is, the lower surface slope 72d of the lower left end in the figure. That is, the grinding wheel is raised relative to the workpiece in the thickness direction. Thereafter, the cover glass W held on the chuck table 73 moves at a constant speed in the Y-axis direction, and chamfering on the third round is performed following FIGS. 12A and 12B.

  Although FIG. 12 demonstrated center part grinding (a), upper part grinding (b), and lower part grinding (c) in this order, it is not restricted to this, Upper part grinding (b), Central part grinding ( The order of a) and lower grinding (c) may be arbitrary. However, the point that grinding (a) at the center portion can be performed first, the shape can be cut out first, and then the upper portion grinding (b) and the lower portion grinding (c) can be performed more carefully and accurately. Is excellent.

  Further, as the work material, particularly when the circular portion as shown in FIG. 2 is mainly used and there is a straight portion such as the OF portion, the grinding of the central portion (a), the grinding of the upper portion (b), Each grinding (c) does not require one round of the outer periphery of the workpiece. For example, if the circular portion is subjected only to the upper grinding (b) and the lower grinding (c), the straight portion is subjected to the central grinding (a), the upper grinding (b), and the lower grinding (c). The surface roughness is good, the processing time is shortened without causing the shape collapse, and the grinding groove 74 can be prevented from being worn, clogged and deformed.

  6, 7, and 12 describe the rising or lowering in the thickness direction of the workpiece, but FIG. 13 illustrates the relationship between the upper surface inclined surface 72 u and the lower surface inclined surface 72 d of the grinding groove 74 of the outer peripheral grinding wheel 72. The relationship between the slope of the grinding groove 74 and the chamfer angle will be described. FIG. 13A shows a state in which the peripheral grinding wheel 72 is not tilted but is in contact with the workpiece W, and the chamfering angles coincide with the angles of the upper and lower slopes 72u and 72d of the grinding groove 74. FIG. .

  In order to perform helical grinding, the state in which the outer peripheral grinding wheel 72 is tilted is shown in FIG. 13B, which is 3 to 15 °, preferably 6 to 10 °. The contact area between 72u and the upper surface of the workpiece W is not significantly different from FIG. Therefore, as already shown in FIG. 11, the upper and lower ends (Tu and Td regions) which are the upper and lower parts of the workpiece W are also inclined in different directions as compared to the central part C. The effect of helical grinding is sufficiently obtained, and the processing distortion and surface roughness are improved in the same manner as the central part. It is also a feature of the above embodiment that the three streaks appear and that the upper and lower portions are formed symmetrically with respect to the center line in the thickness direction of the end face.

  In order to make the explanation easy to understand, by not tilting the peripheral grinding wheel 72 of FIG. 13A, the peripheral grinding wheel 72 is tilted with reference to the fact that the slope of the grinding groove 74 coincides with the chamfering angle. This is shown in FIG. On the contrary, the inclined surface may be matched with the chamfering angle of the workpiece W in FIG. Thereby, even when the amount of grinding is small at the start of processing, the contact area between the upper surface slope 72u and the upper surface of the workpiece W is increased, and the surface roughness of the upper and lower ends of the workpiece W is improved.

DESCRIPTION OF SYMBOLS 10 ... Processing part, 20 ... Supply / recovery part, 30 ... Wafer cassette, 31 ... Cassette table, 40 ... Supply / recovery robot, 50 ... Transfer arm, 60 ... Wafer feeder, 61 ... Fine outer peripheral grinding device, 62 ... Coarse peripheral grinding 65, chuck table drive motor, 66 ... chuck table, 67 ... outer periphery roughing motor, 68 ... outer periphery roughing spindle (rotating shaft), 69 ... outer periphery roughing grinding wheel, 70 ... outer periphery fine grinding motor, 71 outside ... Spindle (rotating shaft), 72 ... outer peripheral fine grinding wheel, 72d ... lower surface slope, 72u ... upper surface slope, 73 ... chuck table, 74 ... grinding groove, 80 ... surface grinder, 81 ... precision stage, 82 ... grinding wheel, 83 ... Work material, 84 ... Vise, 102 ... Touch sensor, 104 ... Liquid crystal display, W ... Wafer, cover glass, work material, y0 ... Appearance of work material Thickness

Claims (8)

A method for manufacturing a substrate, wherein the planar shape is rectangular, and the end face is chamfered with a grinding groove formed on a grinding wheel,
Hold a rectangular substrate on a chuck table of the same shape as the substrate,
As for the size of the chuck table, Q is the distance from the center in the X-axis direction of the substrate, and P is the distance from the center in the X-axis direction of the chuck table. .Times.7, where N is the distance from the center in the Y-axis direction of the substrate and H is the distance from the center in the Y-axis direction of the chuck table, N is 1.3 to 1.7 times H. And
While holding the substrate on the chuck table, the central portion in the thickness direction of the end surface is helically ground at 3 to 15 ° over the entire circumference of the substrate, and the upper and lower portions of the end surface are helically chamfered at a chamfer angle. A method for producing a chamfered substrate, characterized by grinding. In the manufacturing method of the chamfered board | substrate of Claim 1,
A method for producing a chamfered substrate, comprising subjecting a large substrate to chemical strengthening treatment, cutting into a predetermined shape, and performing the helical grinding. In the manufacturing method of the chamfered board | substrate of Claim 1 or 2,
Grinding the upper part of the end surface with the upper surface slope of the grinding groove, and then lowering the substrate in the thickness direction relative to the grinding wheel and grinding again;
Alternatively, the lower end of the end face is ground by the lower slope of the grinding groove, and then the substrate is raised relative to the grinding wheel in the thickness direction and then ground again. A manufacturing method of a substrate. In the manufacturing method of the chamfered board | substrate of any one of Claim 1 to 3,
Grinding the upper or lower portion of the end face to make one round with the grinding groove over the entire circumference, and then lowering or raising the substrate relative to the grinding wheel in the thickness direction; A method for producing a chamfered substrate, characterized by grinding one round. In the manufacturing method of the chamfered board | substrate of any one of Claim 1 to 4,
The method of manufacturing a chamfered substrate, wherein the processing of the end face is performed by grinding the upper part of the end face, grinding the central part, and grinding the lower part, respectively. The method for manufacturing a chamfered substrate according to claim 5,
The method for producing a chamfered substrate, wherein the upper grinding, the central grinding, and the lower grinding are performed so that the end face makes one round with the grinding groove over the entire circumference. In the manufacturing method of the chamfered board | substrate of any one of Claim 1 to 6,
A method of manufacturing a chamfered substrate, wherein the substrate is subjected to masking printing and formation of a sensor electrode on the plane. A method for manufacturing a liquid crystal display device in which a planar shape is rectangular, a cover glass chamfered with a grinding groove formed in a grinding wheel on an end surface, and a touch sensor is incorporated in a liquid crystal panel,
Hold the rectangular cover glass on the chuck table of the same shape as the cover glass,
The size of the chuck table is such that Q is the distance from the center of the cover glass in the X-axis direction and P is the distance from the center of the chuck table in the X-axis direction. When the distance from the center of the cover glass in the Y-axis direction is N and the distance from the center of the chuck table in the Y-axis direction is H, N is 1.3 to 1. 7 times,
While the cover glass is held on the chuck table, the cover glass is helically ground at a central portion of the end surface in the thickness direction of 3 to 15 °, and the upper and lower portions are helically ground at a chamfer angle. A method for manufacturing a liquid crystal display device.