Abrasive tool making process – material – or composition – With carbohydrate or reaction product thereof
Patent
1976-01-20
1977-10-18
Whitehead, Harold D.
Abrasive tool making process, material, or composition
With carbohydrate or reaction product thereof
51 58, 51154, 51325, B24B 900
Patent
active
040540103
ABSTRACT:
An apparatus for grinding the edges of planar workpieces such as semiconductor wafers, wherein an abrasive material is provided on the side of a flexible substrate which is mounted in a cantilevered fashion. By virtue of the flexibility in the substrate, the grinding surface can move in and out, if necessary, in order to accommodate any eccentricities or out-of-round portions of the planar workpiece. In a preferred embodiment for semiconductor wafer processing, the wafer is rotated at a speed in excess of 3000 rpm and as high as, say, 10,000 rpm. The grinding surface is preferably established on a round disc which is centrally supported on a shaft; and loading on the grinding surface is typically in a direction that is generally parallel to the longitudinal axis of the shaft. In order to distribute wear of the abrasive surface evenly around the disc, the disc is permitted to have a relatively slow rotational speed; the rapidly rotating wafer is used to induce rotation of the disc, and a friction restraint is employed to prevent the disc (and its grinding surface) from rotating too fast, i.e., more than about 100 rpm. Preferably, the abrasive material on the grinding surface constitutes diamond bort having a size of about 100 microns. In order to obviate difficulties that might arise due to mechanical resonance in the grinding system, it is preferred that the relative speed between the workpiece and the grinding surface be varied during a grinding operation. Thus, the workpiece may be rotated at a varying speed between, say, 3000 rpm and 1,000 rpm, during a single cycle; any bouncing that may occur as a result of resonance in the system will inevitably be distributed around the workpiece and not concentrated in a single spot. The substrate material on which the abrasive material (diamond bort) is mounted may be a polycarbonate sheet material having a thickness of 20 or 30 mils. Another substrate may be a cloth-like material shaped to form a diaphragm and supported during grinding operations by pressurized fluid in a chamber below the diaphragm.
REFERENCES:
patent: 835964 (1906-11-01), Loesser
patent: 1210221 (1916-12-01), Shimans
patent: 2119954 (1938-06-01), Lippold
patent: 2612729 (1952-10-01), Walley
patent: 3355840 (1967-12-01), Bonning
patent: 3730134 (1973-05-01), Kadi
Headway Research, Inc.
McHugh Charles W.
Whitehead Harold D.
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