JPH061323Y2 - Inner circumference whetstone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to an inner peripheral edge grindstone used for cutting semiconductor wafers and the like, and more particularly to an improvement for preventing damage to a base metal during grinding.

"Prior Art" FIG. 3 is a cross-sectional view showing a state in which a conventional inner peripheral edge grinding wheel 1 is mounted on a fixing jig 2 for mounting on a grinding wheel driving device.

This inner peripheral edge grindstone 1 is formed by forming a diamond abrasive grain layer 4 on the inner peripheral edge of a thin annular base metal 3. On the other hand, the fixing jig 2 includes an annular base portion 6 having a pressing portion 5 formed on the inner peripheral portion thereof, and a clamp ring 7 for sandwiching and fixing the entire outer peripheral edge of the grindstone base metal 3. By pressing the pressing portion 5 against the base metal 3 and tightening the clamp ring 7 to the base portion 6 with the bolts 8, tension is applied to the base metal 3 to improve the plane accuracy.

As a fixing jig of this type, there is a type shown in FIG. The fixing jig 10 is composed of an upper ring 12 and a lower ring 13 which are fixed by bolts 11 by sandwiching the outer peripheral edge of the base metal 3, and a tension ring 14 accommodated in the upper ring 12 is fixed by a bolt 15 to the base metal 3. It is configured to press against and apply tension to it.

"Problems to be solved by the invention" By the way, recently, in order to further improve the plane accuracy of the semiconductor wafer, the tensile strength of the base metal is increased to increase its rigidity, and the tension applied to the base metal by the jig is higher than before. Attempts have also been made to increase the diameter of the grindstone to reduce runout of the grindstone during cutting.

However, in the conventional grindstone 1, if the tensile force of the jig 2 (10) is simply increased by increasing the tensile strength of the base metal 3, the base portion 3 is pressed by the pressing portion 5 (14). The base metal 3 was frequently damaged, and the service life was extremely short, so that the base metal 3 could not be used.

The inventors have made a detailed examination of this fact,
The following findings were obtained. That is, when the conventional grindstone 1 is fixed to the jig 2 (10), the base metal 3 having high rigidity is strongly pressed and deformed, so that a large stress is locally generated in the pressed portion, and the base is also used during grinding. The base metal 3 and the pressing portion 5 (14) rub against each other as the gold 3 vibrates, and the stress generated thereby further accumulates in the pressed portion, eventually causing metal fatigue and breaking.

"Means for Solving Problems" The present invention has been made to solve the above-mentioned problems, and the tensile strength of the portion of the base metal in contact with the jig pressing portion is 80 to 90 times the tensile strength of the inner peripheral portion of the base metal. %, Which allows the stretch of the pressed portion of the base metal to some extent to prevent stress concentration on this portion.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view showing an inner peripheral edge grinding wheel 20 of one embodiment. This grindstone 20 is a thin ring-shaped stainless steel base metal 2
A diamond abrasive grain layer 22 is formed on the inner peripheral edge of the base metal 1, and mounting holes 23 for mounting on a fixing jig are formed near the outer peripheral edge of the base metal 21.

The base metal 21 is processed so that the total tensile strength is 180 kgf or more, preferably 190 kgf or more, and then only the portion 21A on the outer peripheral side of the predetermined boundary line 24 is annealed or the like. The tensile strength of the portion 21A is reduced to 80 to 90% of the tensile strength of the inner peripheral portion 21B. If this ratio is less than 80%, it becomes difficult to apply sufficient tension to the base metal 21, while if it exceeds 90%, a satisfactory effect cannot be obtained. The boundary line 24
As shown in FIG. 2, is set slightly inside the pressed portion P with which the pressing portion 5 of the jig 2 abuts. In addition,
At the time of the above-mentioned annealing treatment, a low-frequency heating device (not shown) having a ring-shaped heating portion is used to cool the inner peripheral portion 21B of the base metal 21 while only the outer peripheral portion 21A is heated to about 10%.
For example, a method of heating to 450 to 600 ° C. for minutes is adopted.

In the inner peripheral edge grindstone 20 having such a configuration, the tensile force of the pressed portion P of the base metal 21 is smaller than that of the inner peripheral portion 21B and is relatively flexible. Even when strongly pressed by the pressing portion 5 of the tool 2 and further rubbed against the pressing portion 5 during grinding, the pressed portion P expands and contracts a little to disperse the stress in a wide range, which causes metal fatigue caused by stress concentration. It is possible to suppress the generation of the base metal, prevent the base metal 21 from breaking, and extend the life.

Further, since the inner peripheral portion 21B of the base metal 21 has a tensile strength higher than that of the conventional grindstone base metal (tensile strength 160 to 180 kgf), it is possible to reduce the runout of the abrasive grain layer 22 during grinding and improve the grinding accuracy. You can

Further, since it can be easily carried out only by heating the outer peripheral portion of the conventional inner peripheral edge grinding stone, there is an advantage that the cost is low.

Although the tensile strength of the entire outer peripheral portion 21A of the base metal 21 is reduced in the above embodiment, the present invention is not limited to this, and by cooling the outer peripheral edge of the base metal 21 during annealing,
A configuration may be adopted in which the tensile strength of only the pressed portion P and its vicinity is reduced.

Further, the inner peripheral edge grinding stone of the present invention can be mounted on any fixing jig by appropriately changing the position where the annealing treatment is performed.

"Effect of the Invention" As described above, the inner peripheral edge grinding stone of the present invention allows the stretch of the pressed portion to some extent by reducing the tensile strength of the pressed portion of the base metal compared to the inner peripheral portion of the base metal. Because it was done,
Even when this part is strongly pressed by the pressing part of the jig and is further rubbed against the pressing part, the stress can be dispersed in a wide range by slightly expanding and contracting the pressed part, which results from stress concentration. It is possible to suppress metal fatigue and prevent breakage of the base metal.

Further, due to the above effect, the tensile strength of the inner peripheral portion of the base metal can be increased as compared with the conventional grindstone, so that the substantial rigidity of the base metal is increased and the runout of the abrasive grain layer during grinding is reduced, It is possible to improve accuracy.

[Brief description of drawings]

FIG. 1 is a plan view of an inner peripheral edge grinding wheel according to an embodiment of the present invention, and FIG.
The figure is a sectional view showing a state in which the whetstone is mounted on a fixing jig. Further, FIG. 3 and FIG. 4 are cross-sectional views showing a state in which conventional inner peripheral edge grindstones are mounted on fixing jigs of different types. 2 ... Fixing jig, 5 ... Jig pressing part, 21 ... Base metal, 21A ... Outer peripheral part, 21B ... Inner peripheral part, P ... Pressed part (pressed part), 22 ... Diamond abrasive grain layer, 23 … Mounting holes, 24… Boundary lines.

Claims (1)

[Scope of utility model registration request] Claims: 1. An abrasive grain layer is formed on the inner peripheral edge of an annular base metal, and its outer peripheral edge is fixed by a fixing jig, and the base metal is pressed by a pressing portion of the fixing jig to tension the base metal. In the inner peripheral edge grindstone, the tensile strength of the portion of the base metal pressed by the jig pressing portion is 80 to 90% of the tensile strength of the inner peripheral part of the base metal. .