Method for grinding plate-formed workpiece and grinding apparatus

Abstract

A method for grinding a plate-formed workpiece having a raised center with a grindstone is provided. The method includes a first holding process including suctioning and holding the plate-formed workpiece against a holder surface of a first chuck table, which is in a shape where a center is raised with respect to an outer circumference thereof; a reaction-force reducing grinding process including grinding a central part of the plate-formed workpiece with the grindstone to reduce a reaction force against a flattening force to be applied to the plate-formed workpiece; a second holding process including suctioning and holding the plate-formed workpiece against a holder surface of a second chuck table, which spreads in parallel to a lower surface of the grindstone; and a finish-grinding process including grinding to finish the plate-formed workpiece with the grindstone.

What is claimed is: 
     
         1 . A method for grinding a plate-formed workpiece having a raised center with a grindstone, comprising:
 a first holding process including suctioning and holding the plate-formed workpiece against a holder surface of a first chuck table, the holder surface of the first chuck table being in a shape where a center is raised with respect to an outer circumference thereof;   a reaction-force reducing grinding process including grinding a central part of the plate-formed workpiece with the grindstone to reduce a reaction force against a flattening force to be applied to the plate-formed workpiece;   a second holding process including suctioning and holding the plate-formed workpiece against a holder surface of a second chuck table, the holder surface of the second chuck table spreading in parallel to a lower surface of the grindstone; and   a finish-grinding process including grinding to finish the plate-formed workpiece with the grindstone.   
     
     
         2 . A grinding apparatus configured to grind the plate-formed workpiece in the method according to  claim 1 , comprising at least:
 the first chuck table including the holder surface where the center is raised toward the lower surface of the grindstone;   the second chuck table including the holder surface spreading in parallel to the lower surface of the grindstone; and   a grinding assembly configured to grind the plate-formed workpiece suctioned and held with one of the first chuck table or the second chuck table.   
     
     
         3 . A method for grinding a plate-formed workpiece having a raised center with a grindstone, comprising:
 a first holding process including suctioning and holding the plate-formed workpiece, in a state where a center of the plate-formed workpiece is raised, against a holder surface of a chuck table, the holder surface spreading in parallel to a lower surface of the grindstone;   a reaction-force reducing grinding process including grinding a central part of the plate-formed workpiece with the grindstone to reduce a reaction force against a flattening force to be applied to the plate-formed workpiece;   a second holding process including suctioning and holding the plate-formed workpiece against the holder surface of the chuck table without forming a gap between the holder surface and a lower surface of the plate-formed workpiece; and   a finish-grinding process including grinding to finish the plate-formed workpiece with the grindstone.   
     
     
         4 . A grinding apparatus configured to grind the plate-formed workpiece in the method according to  claim 3 , comprising at least:
 the chuck table including the holder surface;   a suction path connecting the holder surface and a suction source;   a pressure adjuster device arranged in the suction path, the pressure adjuster device being configured to adjust a negative pressure value of the holder surface; and   a grinding assembly configured to grind the plate-formed workpiece suctioned and held with the chuck table.   
     
     
         5 . A grinding apparatus configured to grind the plate-formed workpiece in the method according to  claim 3 , comprising at least:
 the chuck table having at least two holder surfaces including a central holder surface and an outer circumferential holder surface, the central holder surface and the outer circumferential holder surface being concentric;   a central suction path connecting the central holder surface and a suction source;   an outer circumferential suction path connecting the outer circumferential holder surface and the suction source;   an area changeable device configured to change an area of the at least two holder surfaces; and   a grinding assembly configured to grind the plate-formed workpiece suctioned and held with the chuck table.