JPH11207636A - Cup-like grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cup-like grinding wheel wherein it is difficult for cut powders to stay between an abrasive grain part and a material to be ground and little fluctuation occurs in cutting quality caused by the deposition of cut powders. SOLUTION: A cup-like grinding wheel 10 includes, in one end surface of base metal 12, a plurality of segments 14 and 16 arrayed in a dual circle form. In this case, a distance from the center of the base metal 12 to the inner peripheral side segment 16 is 85 to 99% of a distance from the base metal center to the outer peripheral side segment 14, widths of the protruded parts 14A and 16A of the segments 14 and 16 are in the range of 1 to 3 mm, a separation distance in a base metal radial direction between the segments 14 and 16 is 1 to 15% of the distance of an outer periphery from the base metal center to a ring segment 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cup-type grindstone used for various types of surface grinding.

[0002]

2. Description of the Related Art A cup-shaped grindstone is formed by fixing a large number of curved rectangular abrasive grain layer segments on one end surface of a cup-shaped base along a circumference centered on the base metal axis. Used for various surface grinding.

[0003] Among these types of surface grinding, the one requiring particularly high planarity is wafer surface grinding. In general surface grinding of a wafer, as shown in FIGS. 12 and 13, one annular groove is formed on one end surface of the cup-shaped base 3 and a curved rectangular parallelepiped abrasive is formed in the groove. A cup-shaped grindstone 2 in which a number of layer segments 4 are fitted and fixed is used. Then, the wafer W was coaxially fixed on the lower platen 1 of the grinding device, and the cup-shaped grindstone 2 fixed to the upper platen was eccentric from the center of the lower platen 1 while rotating the lower platen 1 around the axis. The upper surface of the wafer W is surface-ground by rotating in this state and bringing the abrasive layer segment 4 into contact with the upper surface of the wafer W in parallel.

[0004]

By the way, in the conventional cup-type grindstone, even if the grinding is performed while the grinding fluid is continuously supplied, fine chips generated by the grinding remain in the abrasive layer segment 4 and the wafer W. And the sharpness fluctuates remarkably.
The same problem can be said when grinding a work material other than a wafer.

The present invention has been made in view of the above circumstances, and provides a cup-type grindstone in which chips are less likely to accumulate between an abrasive portion and a work material, and the variation in sharpness caused by the accumulation of chips is small. The challenge is to do.

[0006]

In order to solve the above-mentioned problems, a cup-shaped grindstone according to the present invention is provided on one end surface of a cup-shaped base along each of multiple imaginary or double circular imaginary lines. Wherein a plurality of abrasive grains are arranged.

According to such a cup-type grindstone, since the width of the abrasive portion can be reduced, chips are less likely to accumulate at the interface between the abrasive portion and the work material, and the sharpness caused by the accumulation of chips is reduced. Little fluctuation. Therefore, it is possible to improve and uniform the grinding accuracy.

In particular, for wafer grinding, the distance from the center of the base metal to the innermost peripheral abrasive portion is 85 to 99% of the distance from the center of the base metal to the outermost peripheral abrasive portion. The width of the abrasive portion in the radial direction of the base metal is 1 to 3 mm, and the separation distance in the radial direction of the base metal of the abrasive portions arranged along the imaginary lines adjacent to each other is located at the outermost periphery from the center of the base metal. Preferably, the distance is 1 to 15% of the distance to the abrasive grains.

[0009]

1 and 2 are a bottom view and a partial sectional view showing an embodiment 10 of a cup-type grindstone according to the present invention. The main characteristic of the cup-shaped grindstone 10 of this embodiment is that a plurality of abrasive grain layer segments 14 and 16 are arranged in a coaxial double circle on one end surface of an annular cup-shaped base 12. And

The base 12 of this embodiment is formed in an annular shape having a central hole 24, and an annular shallow recess 22 is formed coaxially with the center of the base over the entire circumference on the inner peripheral side of the lower surface thereof. ing. An outer circumferential groove 18 and an inner circumferential groove 20 having a fixed opening width and depth are formed coaxially with the center of the base metal on the lower end surface of the base metal 12 located outside the recess 22.
The outer segment 14 and the inner segment 16 are fixed to each other at equal intervals in the circumferential direction.

The shape and material of the metal base 12 are not limited to those shown in the figures, and may be any shape and material as long as it has been conventionally used for this type of cup-type grindstone. In this embodiment, a plurality of bolt holes 26 are formed in the upper end surface of the base metal 12 at intervals in the circumferential direction, and can be attached to an upper surface plate of a grinding device (not shown) via these bolt holes 26. Have been.

As shown in FIG. 2, each of the outer peripheral side segment 14 and the inner peripheral side segment 16 of this embodiment has an L-shaped cross section having protruding portions 14A, 16A, and is curved in a plan view. Has made. The projections 14A and 16A are L-shaped in cross section.
This is because, even when the width of the segment 14 is reduced, the mounting strength of the segments 14 and 16 to the base metal 12 can be sufficiently increased. However, the present invention is not limited to this structure. For example, the segments 14 and 16 may be rectangular in cross section, or may be trapezoidal in cross section in which the width decreases from the upper end to the lower end.

The depth of the outer peripheral groove 18 and the inner peripheral groove 20 is a value obtained by subtracting the height of the protrusions 14A, 16A from the height of the segments 14, 16, and
Are inserted into the grooves 18 and 20 and brazed or adhered. The height of the protrusions 14A and 16A is preferably about 0.5 to 1.5 times the width of the protrusions 14A and 16A in the base metal radial direction from the viewpoint of strength.

The radius of curvature of each of the segments 14 and 16 in a plan view is substantially equal to the radius of curvature of the outer peripheral groove 18 and the inner peripheral groove 20 into which they are fitted. The outer segment 14 and the inner segment 16 may have different curvatures from each other. However, if the base metal 12 has a sufficiently large diameter and the distance D between the segments is sufficiently small, the segments 14 and 16 may be the same. Segment 14,
The 16 projections 14A, 16A are arranged facing each other, whereby the segment 1
The separation distance D can be made sufficiently small while securing the fixing strength of 4,16.

In this embodiment, as shown in FIG. 1, the gap between the outer segments 14 and the inner segment 1
The arrangement of the segments 14 and 16 is shifted by about a half pitch so that the gap between the six does not coincide with the base metal radial direction. With this configuration, the grinding fluid supplied to the center side of the base metal 12 passes through the gap between the inner segments 16, passes through the gap between the segments 14 and 16, and further passes through the gap between the outer segments 14. It is designed to flow out, which enhances the cleaning and cooling effect of the segments 14,16. However, the present invention is not limited to only such alternate segment sequences.

The dimensions of the base metal 12 and the segments 14 and 16 are not limited, but if a preferable value for the wafer grinding is shown as an example, the distance from the center of the base metal 12 to the outer peripheral edge of the protrusion 16A of the inner peripheral side segment 16 is as follows. The distance from the center of the base metal 12 to the outer peripheral edge of the protrusion 14A of the outer peripheral side segment 14 is desirably 85 to 99%, more preferably 90 to 98%. Further, the width of the protrusions 14A and 16A in the base metal radial direction is desirably 1 to 3 mm,
More preferably, it is 1.5 to 2 mm. Furthermore,
The distance D between the adjacent protrusions 14A and 16A is preferably 1 to 15% of the distance from the center of the base metal to the outer peripheral edge of the outermost protrusion 14A, and more preferably 2 to 10%. It is said. Generally, the separation distance D is 2 to 5 m.
m, more preferably about 2.5 to 4 mm. Within such a range, the wafer can be accurately and efficiently ground.

The length of the segments 14 and 16 is not limited, but is preferably about 10 to 40 mm for wafer grinding. Furthermore, the circumferential gap between the segments 14 and 16 is not limited, but is preferably about 1 to 3 mm for wafer grinding.

The segments 14, 16 may be made of any conventionally used material. That is, super abrasive grains such as diamond and CBN or Si
A metal bond abrasive layer formed by hardening general abrasive grains such as C and Al ₂ O ₃ with a metal binder, or a resin bond abrasive layer formed by hardening the abrasive grains with various resin binders. Or
It may be a vitrified bond abrasive grain layer in which the abrasive grains are solidified with a glass binder or the like, or may be an electrodeposited abrasive grain layer in which the abrasive grains are fixed with an electrodeposited metal or an electroformed abrasive grain layer. However, when used for wafer grinding, a resin bonded abrasive layer in which superabrasives such as diamond and CBN are hardened with various resins is most preferable.

The materials of the segments 14 and 16 may be different from each other. For example, only the outer segment 14 having a higher rotational peripheral speed is formed by a relatively hard abrasive layer which is less likely to be worn than the inner segment 16. It may be formed.
Alternatively, the inner segment 16 is replaced with the outer segment 1
By forming with an abrasive layer containing abrasive grains smaller than 4, sharp preliminary grinding is performed on the outer peripheral side segment 14 and finish grinding is performed on the inner peripheral side segment 16 to obtain surface accuracy and surface quality. You may.

The segments 14 and 16 of this embodiment include:
It is fixed in the grooves 18 and 20 by brazing or bonding. However, the present invention is not limited to this mounting method, and may be brazed to the base metal 12 without forming the grooves 18 and 20, or another fixing method may be adopted. In addition,
The four corners of the segments 14 and 16 may be appropriately rounded, or four sides of the segments 14 and 16 may be chamfered in advance.

With the cup-shaped grindstone 10 as described above,
For example, to perform surface grinding of a wafer, first, as shown in FIG. 10, a wafer W to be polished is fixed coaxially on a lower surface plate 1 of a surface grinding device, and the lower surface plate 1 is rotated at a constant speed around an axis. Rotate. On the other hand, the cup-type grindstone 10 is fixed to an upper surface plate (not shown) and rotated around its axis. Then, the lower end surfaces of the projections 14A, 16A of the segments 14, 16 are brought into parallel contact with the surface to be ground of the wafer.

At this time, the relative position between the wafer W and the cup-type grindstone 10 is such that the center point of the wafer W is the grinding area 40 or 4 formed by the protrusions 14A and 16A as shown in FIG.
It is desirable to enter any of the two. When grinding is performed in such a positional relationship, the entire surface of the wafer W can be ground uniformly without leaving uncut portions at the center of the wafer W.

According to the cup-shaped grindstone having the above structure,
Since the width of each protruding portion 14A, 16A for shaving a wafer is smaller than that of a conventional cup-shaped grindstone in which the segments are arranged in a line, the dischargeability of chips from the grinding portion where the protruding portions 14A, 16A and the wafer abut. Is good, and the sharpness and the fluctuation of the grinding resistance due to the accumulation of the chips are less likely to occur.
It is possible to improve the uniformity of the grinding and the grinding efficiency.

Further, by arranging the segments 14 and 16 in two rows, even if the width of the segments 14 and 16 is reduced, the contact area between the segment and the wafer can be secured to the same level as in the conventional case. In addition, it is possible to prevent generation of streak-like grinding marks, and it is possible to improve planar accuracy.

Also, by arranging the segments 14 and 16 alternately, the grinding fluid supplied to the center side of the base metal 12 efficiently cleans and cools the segments 14 and 16. In addition, it is possible to prevent a decrease in grinding accuracy due to a rise in temperature.

[Second Embodiment] FIGS. 3 and 4 show a second embodiment of a cup-type grindstone according to the present invention. In the second embodiment, a liquid receiving groove 34 opening on the upper surface of the base 12 is formed, and a number of liquid supply holes 32 opening from the outer peripheral portion of the bottom surface 34B of the liquid receiving groove 34 to the lower end surface of the base 12 are formed. It is a new feature that it is formed.

The liquid receiving groove 34 is formed coaxially with the center of the base metal, and is located outside the bolt hole 26 and inside the inner peripheral side segment 16. The outer circumferential side surface of the liquid receiving groove 34 is a slope 34A extending downward and outward,
The grinding liquid supplied into the liquid receiving groove 34 during the grinding flows below the slope 34 </ b> A by centrifugal force and is efficiently introduced into the liquid supply hole 32.

The liquid supply hole 32 radially extends downward and outward from the liquid receiving groove 34, and is located inside the inner peripheral side segment 16.
In addition, it is opened at a position corresponding to substantially the center of the inner peripheral side segment 16. As a result, the grinding fluid discharged from the liquid supply hole 32 by centrifugal force first strikes the inner peripheral surface of the inner peripheral side segment 16, passes between the inner peripheral side segments 16, and passes through the gap between the segments 14 and 16. Then, it flows out through the gap between the outer peripheral side segments 14 to the outside.
Thereby, the cleaning and cooling effects of the segments 14 and 16 are enhanced.

[Third Embodiment] FIGS. 5 and 6 show a third embodiment of a cup-type grindstone according to the present invention. The third embodiment is characterized in that a liquid receiving groove 34 and a liquid supply hole 32 are formed on the outer peripheral side as compared with the second embodiment, and the lower end of the liquid supply hole 32 is opened between the segments 14 and 16. I do. Other configurations may be the same as in the second embodiment. According to this embodiment, the segments 14, 1 which are particularly easily clogged.
It is possible to circulate the grinding fluid intensively during 6.

Fourth Embodiment FIG. 7 shows a fourth embodiment of the cup-type grindstone according to the present invention. The fourth embodiment is characterized in that the segments 14, 16 are aligned in the base metal radial direction. In this case, between the outer peripheral segments 14 and between the inner peripheral segments 16.
It is possible to distribute the grinding fluid intensively between them.

[Fifth Embodiment] FIG. 8 shows a fifth embodiment of the cup-type grindstone according to the present invention. In the fifth embodiment, an abrasive layer segment 36 having a U-shaped cross section is used, and the protrusions 36A, 3A formed on the segment 36 are used.
6B is used as an abrasive part. In the case of adopting a segment arrangement in which the abrasive grains are aligned in the base metal radial direction as in the fourth embodiment, such a U-shaped segment 36 can also be used. The shape and size of each part except the segment 36 may be the same as in the second embodiment.

Sixth Embodiment FIG. 9 shows a sixth embodiment of the cup-type grindstone according to the present invention. In the sixth embodiment, the center point O1 of the arrangement line of the outer peripheral side segment 14 is set.
And the center point O2 of the arrangement line of the inner peripheral side segment 16 is different. That is, the center point O1 of the arrangement line of the outer peripheral side segment 14 is located on the opposite side to the center point O2 of the arrangement line of the inner peripheral side segment 16 with the center point O of the base metal 12 interposed therebetween.

When the center point O1 of the arrangement line of the outer peripheral segment 14 and the center point O2 of the arrangement line of the inner peripheral segment 16 are shifted from the center point O of the base metal as shown in FIG.
As shown in FIG. 10, while the protruding portions 14A and 16A swing in the base metal radial direction, the larger areas 44 and 46 than in the case of FIG.
Since the wafer W is ground in the inside, the uncut portion hardly occurs at the center of the wafer, and the flatness of the wafer can be improved.

The distance between the center point O1 and the center point O and the distance between the center point O2 and the center point O are both preferably about 0.5 to 6 mm, and more preferably about 1 to 4 mm. If it is too small, the effect cannot be obtained. If it is too large, the oscillating grinding ranges 44 and 46 become too wide.
Conversely, the planar accuracy of the wafer is reduced. When the segment arrangement line is eccentric as in this embodiment, the distance from the center of the base metal to the abrasive portion means the maximum value.

The present invention is not limited to the above embodiments, and the configurations of the embodiments may be combined with each other. Further, the segment arrangement may be changed to a triple circle or more, or each segment arrangement may be changed to an elliptical shape instead of a perfect circle. further,
The cup-type grindstone of the present invention is not only used for wafer grinding, but can also be used for grinding other workpieces.

[0036]

EXAMPLES Next, the effects of the present invention will be demonstrated with reference to examples. Example 1 corresponding to each of the first to sixth embodiments
6 were actually prepared, and a grinding test was performed together with a conventional cup-shaped grindstone (comparative example) to compare the grinding power, the wafer flatness, and the number of wafers ground before the burn was caused.

The dimensions common to all Examples and Comparative Examples are as follows. Outer diameter of outer peripheral surface of abrasive layer segment (outermost): 250 m
m Average particle diameter of diamond abrasive grains used: 6.2 μm Abrasive grain content in abrasive grain layer segment: 25 vol% Composition of binder: phenolic resin 75 vol% + CaF ₂
25 vol%

In Examples 1 to 6, the width of the abrasive grain layer segment was 2 mm, and the abrasive grain layer segments were arranged in a double circle. In Examples 1 to 5, the distance D between the outer segment and the inner segment was 3 mm. In Example 6 corresponding to Embodiment 6 (eccentric type) in FIG. 9, the outer diameter of the outer peripheral surface of the inner peripheral segment was 230 mm, the distance from the grinding wheel center O to the center O1 of the outer peripheral segment was 2.5 mm, The distance from the grinding wheel center O to the center O2 of the inner peripheral side segment was 2.5 mm. On the other hand, in the comparative example, the width of the abrasive grain layer segments was set to 4 mm, and they were arranged in a single circle coaxial with the center of the grindstone. In both the examples and the comparative examples, the distance between the segments adjacent in the circumferential direction was unified to 2 mm.

The conditions of the grinding test were as follows. Work material: 6 inch diameter silicon wafer after lapping Grinding wheel rotation speed: 2500 rpm (peripheral speed about 2000 m / mi)
n) Cutting depth: 80 μm / min Cutting allowance: 200 μm (wafer initial thickness average 630 μm)
m) Apparatus used: vertical surface grinder Grinding fluid: pure water (in the embodiment having a liquid supply path, also supplied from the liquid supply path)

Under the above-mentioned grinding conditions, ten wafers were ground, and the average value of the grinding power (A) and the average value of the wafer flatness (TTV) were measured. Thereafter, the grinding was further continued to determine the number of wafers to be ground until the burn was caused. Table 1 shows the results.

[0041]

[Table 1]

As is evident from Table 1, Examples 1 to 6 according to the present invention were superior in sharpness to Comparative Examples, and the grinding power was reduced. Also, the flatness of the wafer was improved. Furthermore, it was found that the number of wafers before the occurrence of grinding burn was significantly increased, so that clogging was difficult.

[0043]

As described above, according to the cup-type grindstone according to the present invention, individual abrasive grains for cutting a work material are compared with a conventional cup-type grindstone in which abrasive grains are arranged in a single circle. Since the width of the part can be made smaller, the discharge of chips from the grinding part where the abrasive part and the wafer are in contact is good, and the sharpness and the fluctuation of the grinding resistance due to the accumulation of the chips are less likely to occur. And the grinding efficiency can be improved.

Further, by arranging the abrasive grains in multiple circles, it is possible to ensure the same contact area between the abrasive grains and the work material as before even if the width of the abrasive grains is reduced. Since it is possible, it is possible to prevent local variation in the attraction of the chips and to prevent the occurrence of streaky grinding marks.

[Brief description of the drawings]

FIG. 1 is a bottom view showing a first embodiment of a cup-type grindstone according to the present invention.

FIG. 2 is a partial sectional view of the cup-type grindstone of the first embodiment.

FIG. 3 is a bottom view showing a second embodiment of the cup-type grindstone according to the present invention.

FIG. 4 is a partial sectional view of a cup-type grindstone according to a second embodiment.

FIG. 5 is a bottom view showing a third embodiment of the cup-type grindstone according to the present invention.

FIG. 6 is a partial sectional view of a cup-type grindstone according to a third embodiment.

FIG. 7 is a bottom view showing a fourth embodiment of the cup-type grindstone according to the present invention.

FIG. 8 is a partial sectional view of a fifth embodiment of the present invention.

FIG. 9 is a bottom view showing a sixth embodiment of the cup-type grindstone according to the present invention.

FIG. 10 is an explanatory diagram showing the operation of the first embodiment.

FIG. 11 is an explanatory diagram showing the operation of the sixth embodiment.

FIG. 12 is a side view showing a conventional wafer surface grinding method.

FIG. 13 is a plan view showing a conventional wafer surface grinding method.

[Explanation of symbols]

 W Wafer 10 Cup-type grindstone 12 Base metal 14 Outer peripheral segment 16 Inner peripheral segment 18 Outer peripheral groove 20 Inner peripheral groove 14A, 16A Projecting portion (abrasive portion) 28, 30 Segment gap D Separation distance 32 Liquid supply hole 34 Liquid receiving Groove 34A Slope O1 Center point O2 Center point 40, 42, 44, 46 Grinding area

Claims (7)

[Claims] 1. A cup-type grindstone having a plurality of abrasive grains arranged on one end surface of a cup-type base along respective imaginary lines forming a multi-circle. 2. A cup-type grindstone characterized in that a plurality of abrasive grains are arranged on one end surface of a cup-type base along respective imaginary lines forming a double circle. 3. The distance from the center of the base metal to the abrasive grain located at the innermost periphery is 85 to 99% of the distance from the center of the base metal to the abrasive grain located at the outermost periphery, The width of the abrasive grains in the metal shell radial direction is 1 to 3 mm, and the separation distance in the metal shell radial direction of the abrasive grains arranged along adjacent virtual lines is the outermost circumference from the center of the metal shell. 3. The cup-type grindstone according to claim 1, wherein the distance is 1 to 15% of the distance to the abrasive grain portion located at (1). 4. The abrasive grain portion according to claim 1, wherein each of the abrasive grain portions is formed by fitting an abrasive grain layer segment having an L-shaped cross section into an annular groove formed in the base metal. Item 4. The cup-type grindstone according to any one of Items 1 to 3. 5. A concave portion for receiving a grinding fluid supplied to the other end surface is formed in the other end surface of the base metal, and a liquid supply hole communicating with the concave portion is formed in one end surface of the base metal. The cup-shaped grindstone according to any one of claims 1 to 4, wherein is formed. 6. The cup mold according to claim 1, wherein one or more of the center points of the imaginary lines forming the multiple circles are offset from the axis of the base metal. Whetstone. 7. One or more of the center points of each of said imaginary lines forming a multi-circle are displaced in a first direction as viewed from said base metal axis, and the other one or more of said center points are connected to said platform. 7. The cup-type grindstone according to claim 6, wherein the wheel is displaced in a second direction opposite to the first direction when viewed from a gold axis.