Abrading – Machine – Rotary tool
Reexamination Certificate
1998-03-31
2001-10-02
Butler, Rodney A. (Department: 3725)
Abrading
Machine
Rotary tool
Reexamination Certificate
active
06296553
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a grinding method and a surface grinder for minutely grinding single or both surfaces of a workpiece, such as a thin-plate-like hard wafer to be used for a semiconductor, with extremely high accuracy.
In addition, the present invention relates to a workpiece support mechanism, and a work rest.
Further, the present invention also relates to a surface grinder having a contact preventing apparatus for preventing the workpiece supporting member from being contacted with a grinding wheel.
Conventionally, after having been sliced off from an ingot through use of an inner blade saw or wire saw, a wafer, such as a silicon wafer, is ground by a lapping machine.
The wafer sliced off from the ingot is rough in terms of surface roughness and accuracy of geometry. It takes very long time to lap the wafer sliced off from the ingot, resulting in deterioration of working efficiency. At the time of grinding of one surface of the wafer, another surface of the wafer is held by a vacuum chuck. For this reason, although the wafer sliced off from the ingot is plane in shape while being held, the wafer tends to become warped after removal of the workpiece from the vacuum chuck.
In a case where, with a view to improving the efficiency and accuracy of a lapping operation, an attempt is made to grind the wafer, a required degree of accuracy is obtained in a very short time. However, if the wafer is held by the vacuum chuck as a conventional matter, a required degree of accuracy cannot be obtained. This is a problem.
Conventional grinding method for a wafer is, however, known and described in, e.g., Japanese Utility Model No. 3028734; “Machines and Tools,” July, 1996, pp. 60-64; and “Proceedings of Abrasive Engineering Society”, July, 1995, vol. 3, No. 4, pp. 20-23.
Generally, a conventional double disc surface grinder comprises upper and lower rotary spindles rotatively arranged in alignment with each other. Grinding wheels (so called grindstone) are held and secured to the respective ends of the rotary spindles which are opposite to each other by upper and lower grinding wheel holders. The grinding wheels are positioned so as to be opposite to each other such that the grinding surfaces of the grinding wheels are arranged in parallel with each other. A workpiece hold mechanism for supporting a workpiece is provided between the grinding wheels so as to be movable, and a workpiece support plate is provided for the workpiece hold mechanism. While the workpiece is retained by the workpiece support plate, both grinding wheels are rotated and moved close to the workpiece. Both surfaces of the workpiece are ground so as to be parallel to each other by grinding surfaces of the grinding wheels. At that time, the surface grinder is operated in such a manner that the workpiece is only ground by the upper and lower grinding wheels without grinding of the workpiece support plate.
On the other hand, in many cases, the workpiece support plate becomes warped by its dead weight. At the time of grinding of the workpiece, it has been difficult to retain the workpiece support plate while being kept from contact with the grinding wheels.
It is conceivable that the workpiece support plate is stretched in the form of a very thin sheet. However, in such a case, it is difficult for the workpiece support sheet to stand the grinding torque exerted on the workpiece during a machining operation.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problem in the conventional techniques, and to provide a grinding method, a surface grinder, a work support mechanism or a work rest in which required surface roughness and accuracy of geometry are achieved in a short time.
In addition, it is also an object of the present invention to provide a surface grinder having a contact preventing apparatus for preventing a workpiece supporting element from being contacted with a grinding wheel.
The above-mentioned object can be attained by a surface grinder, according to the present invention, comprises:
a rotary disk having one of a recess and a through hole into which a workpiece having an engaged portion can be loosely fitted with a fine clearance, and also having a workpiece drive section provided with the one so as to be engaged with the engaged portion of the workpiece;
a grinding wheel for grinding the surface of the workpiece loosely fitted in the one of the recess and the through hole while the end face of the grinding wheel is directed towards the workpiece;
a spindle for rotating the grinding wheel;
a support member for rotatively supporting the rotary disk; and
rotational drive means for rotating the rotary disk,
wherein when the rotary disk is rotated, a torque developing in the rotary disk is transferred to the workpiece drive section so as to rotate the workpiece relative to the support member.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously, the grinding wheel is an upper grinding wheel which is arranged so as to be opposite to the upper surface of said workpiece in the vertical direction of the surface grinder, and
the recess is formed in the rotary disk.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously,
the grinding wheel comprises upper and lower grinding wheels arranged so as to respectively face both surfaces of the workpiece in the vertical direction of the surface grinder; and
the through hole is formed in the rotary disk.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously,
In the above-mentioned construction of the surface grinder according to the present invention, advantageously,
the upper and lower grinding wheels are different from each other in terms of magnitude of grinding ability.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously,
the grinding wheel is a cup-shaped grinding wheel;
the workpiece is substantially circular; and
the center of the workpiece is arranged so as to permit overlap between the center and the grinding surface of the cup-shaped grinding wheel.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously, the rotational drive means comprises:
a motor supported on the support member; and
a torque transfer mechanism interposed between the motor and the rotary disk.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously, the support member comprises:
a slide table for rotatively supporting the rotary disk; and
guide member, along which the slide table is movable, extended in a direction perpendicular to the rotational axis of the grinding wheel.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously,
the workpiece drive section is formed from a material which is softer than that of the workpiece.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously, the rotary disk comprises:
a substantially-annular rotary metal plate body; and
a workpiece loosely fitting member provided along the internal periphery of the rotary body and formed from a material which is softer than that of the workpiece.
In the above-mentioned construction of the surface grinder according to the present invention, advantageously, the workpiece drive section is integrally formed from the rotary disk.
In addition, the above-mentioned object can be attained by a workpiece support mechanism, according to the present invention, comprises:
a rotary disk having one of a recess and a through hole into which a workpiece having an engaged portion can be loosely fitted with a fine clearance, and also having a workpiece drive section provided with the one so as to be engaged with the engaged portion of the workpiece;
a support member for rotatively supporting the rotary disk; and
rotational d
Murai Shirou
Nakajima Kazuo
Nishi Kenichiro
Nukui Mitsuru
Wada Toyotaka
Butler Rodney A.
Nippei Toyama Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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