Polishing pad with uniform abrasion
Patent 5020283 Issued on June 4, 1991. Estimated Expiration Date: 
August 3, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
August 3, 2010. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2409953 3495362 3517466 Method for machining workpieces of brittle hard material into wafers Patent #: 4663890 InventorApplicationNo. 562288 filed on 08/03/1990US Classes:451/550, Disk laps451/527, Interrupted or composite work face (e.g., cracked, nonplanar, etc.)451/548, Rotary diskD15/122MATERIAL WORKING, ABRADING, OR FOUNDING MACHINERYExaminersPrimary: Schmidt, Frederick R.Assistant: Shideler, Blynn Attorney, Agent or FirmInternational ClassesB24B 007/22109 R DIG. 34 AbstractA polishing pad for semiconductor wafers, having a face shaped by a series of voids. The voids are substantially the same size, but the frequency of the voids increases with increasing radial distance to provide a constant, or nearly constant, surface contact rate to a workpiece such as a semiconductor wafer, in order to effect improved planarity of the workpiece. | |
