Polishing pad
Patent 5177908 Issued on January 12, 1993. Estimated Expiration Date: 
January 22, 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.
January 22, 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. 468348 filed on 01/22/1990US Classes:451/41, Glass or stone abrading451/287, Planar surface abrading451/527, Interrupted or composite work face (e.g., cracked, nonplanar, etc.)451/548, Rotary disk451/550, Disk laps451/921, "PAD" FOR LENS SHAPING TOOLD15/122MATERIAL WORKING, ABRADING, OR FOUNDING MACHINERYExaminersPrimary: Schmidt, Frederick R.Assistant: Shideler, Blynn International ClassesB24B 007/22131.1-131.5 AbstractA polishing pad for semiconductor wafers, having a face shaped 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. The favored face shape is a sunburst pattern having nontapered rays, coaxial with the pad's rotation. | |
