Dressing apparatus, dressing method, and method of manufacturing device chips

Abstract

A dressing apparatus dresses grindstones for grinding a workpiece by causing the grindstones and a dresser board to slide abrasively against each other. The dressing apparatus includes a board holder for holding the dresser board, a moving mechanism for moving the board holder and the grindstones relatively to each other in a direction transverse to a plane along which the grindstones abrasively slide against the dresser board, and a measuring instrument for detecting a load applied to the dresser board.

What is claimed is: 
     
         1 . A dressing apparatus for dressing grindstones that grinds a workpiece by causing the grindstones and a dresser board to slide abrasively against each other, comprising:
 a board holder for holding the dresser board;   a moving mechanism for moving the board holder and the grindstones relatively to each other in a direction transverse to a plane along which the grindstones abrasively slide against the dresser board; and   a measuring instrument for detecting a load applied to the dresser board.   
     
     
         2 . The dressing apparatus according to  claim 1 , in which the moving mechanism includes a mechanism for moving the board holder with respect to the grindstones, further comprising:
 a measurement reference marker disposed in a path along which the dresser board is to be moved by the moving mechanism.   
     
     
         3 . The dressing apparatus according to  claim 1 , in which the moving mechanism includes an actuator for moving the board holder with respect to the grindstones, further comprising:
 a guide for limiting movement of the board holder in directions transverse to the directions in which the actuator moves the board holder.   
     
     
         4 . The dressing apparatus according to  claim 2 , in which the moving mechanism includes an actuator for moving the board holder with respect to the grindstones, further comprising:
 a guide for limiting movement of the board holder in directions transverse to the directions in which the actuator moves the board holder.   
     
     
         5 . The dressing apparatus according to  claim 1 , further comprising:
 a workpiece holder for holding the workpiece; and   a grinding actuator on which there is mounted a grinding wheel rotatable about its central axis, the grindstones being mounted on the grinding wheel, wherein   the grinding wheel is rotated to rotate the grindstones and the grinding actuator is operated to bring the grindstones into contact with the workpiece held by the workpiece holder thereby to grind the workpiece, and   the grinding wheel is rotated to rotate the grindstones and the grinding actuator is operated to bring the grindstones into contact with the dresser board held by the board holder thereby to dress the grindstones.   
     
     
         6 . The dressing apparatus according to  claim 2 , further comprising:
 a workpiece holder for holding the workpiece; and   a grinding actuator on which there is mounted a grinding wheel rotatable about its central axis, the grindstones being mounted on the grinding wheel, wherein   the grinding wheel is rotated to rotate the grindstones and the grinding actuator is operated to bring the grindstones into contact with the workpiece held by the workpiece holder thereby to grind the workpiece, and   the grinding wheel is rotated to rotate the grindstones and the grinding actuator is operated to bring the grindstones into contact with the dresser board held by the board holder thereby to dress the grindstones.   
     
     
         7 . The dressing apparatus according to  claim 1 , wherein the grinding wheel is rotated to rotate the grindstones and the grinding actuator is operated to bring the grindstones into contact with the dresser board thereby to dress the grindstones irrespectively of whether the grindstones are not grinding the workpiece or the grindstones are grinding the workpiece held by the workpiece holder. 
     
     
         8 . The dressing apparatus according to  claim 2 , wherein the grinding wheel is rotated to rotate the grindstones and the grinding actuator is operated to bring the grindstones into contact with the dresser board thereby to dress the grindstones irrespectively of whether the grindstones are not grinding the workpiece or the grindstones are grinding the workpiece held by the workpiece holder. 
     
     
         9 . The dressing apparatus according to  claim 1 , further comprising:
 a liquid supply nozzle for supplying a liquid to the dresser board held by the board holder.   
     
     
         10 . The dressing apparatus according to  claim 2 , further comprising:
 a liquid supply nozzle for supplying a liquid to the dresser board held by the board holder.   
     
     
         11 . The dressing apparatus according to  claim 1 , further comprising:
 a cleaning nozzle for supplying a fluid to the grindstones, wherein   the grinding wheel, the workpiece holder, and the board holder are disposed such that a path followed by the grindstones rotated by the grinding wheel when the grinding wheel is rotated overlaps a portion of the workpiece held by the workpiece holder and overlaps a portion of the dresser board held by the board holder as viewed in a direction transverse to a plane along which the grindstones are rotated, and   the cleaning nozzle is disposed to supply the fluid at a position out of contact with the workpiece held by the workpiece holder and the dresser board held by the board holder on the path followed by the grindstones as viewed in the direction transverse to the plane along which the grindstones are rotated.   
     
     
         12 . The dressing apparatus according to  claim 2 , further comprising:
 a cleaning nozzle for supplying a fluid to the grindstones, wherein   the grinding wheel, the workpiece holder, and the board holder are disposed such that a path followed by the grindstones rotated by the grinding wheel when the grinding wheel is rotated overlaps a portion of the workpiece held by the workpiece holder and overlaps a portion of the dresser board held by the board holder as viewed in a direction transverse to a plane along which the grindstones are rotated, and   the cleaning nozzle is disposed to supply the fluid at a position out of contact with the workpiece held by the workpiece holder and the dresser board held by the board holder on the path followed by the grindstones as viewed in the direction transverse to the plane along which the grindstones are rotated.   
     
     
         13 . A dressing method of dressing grindstones for grinding a workpiece, using a dressing apparatus including a board holder for holding a dresser board, in which the dressing apparatus causes the dresser board held by the board holder and the grindstones to slide abrasively against each other, the dressing method comprising:
 dressing the grindstones, using the dressing apparatus by
 measuring a load applied to the dresser board, and 
 pressing the board holder and the grindstones against each other in a direction transverse to a plane along which the grindstones and the dresser board slide abrasively against each other such that the measured load applied to the dresser board has a value falling within a predetermined numerical range. 
   
     
     
         14 . The dressing method according to  claim 13 , in which the dressing apparatus further includes a moving mechanism for moving the board holder with respect to the grindstones in the direction transverse to the plane along which the grindstones and the dresser board slide abrasively against each other, and a measurement reference marker disposed in a path followed by the dresser board when the board holder is moved by the moving mechanism, the dressing method further comprising:
 moving the board holder by the moving mechanism and recording information about a position of the board holder at the time the dresser board held by the board holder and the measurement reference marker contact each other; and   controlling a distance that the board holder is moved by the moving mechanism on the basis of the recorded information about the position of the board holder.   
     
     
         15 . The dressing method according to  claim 13 , in which the dressing apparatus further includes a moving mechanism for moving the board holder with respect to the grindstones in the direction transverse to the plane along which the grindstones and the dresser board slide abrasively against each other, the dressing method further comprising:
 moving the board holder by the moving mechanism and recording information about a position of the board holder at the time the board holder or the dresser board held by the board holder and the grindstones contact each other; and   controlling a distance that the board holder is moved by the moving mechanism on the basis of the recorded information about the position of the board holder.   
     
     
         16 . The dressing method according to  claim 13 , wherein
 the grindstones are dressed by using the dressing apparatus by either bringing the dresser board into contact with the grindstones while the grinding stones are grinding the workpiece or bringing the dresser board into contact with the grindstones while the grinding stones are not grinding the workpiece.   
     
     
         17 . A method of manufacturing device chips by dividing a workpiece, the method comprising:
 dressing grindstones for grinding a workpiece, using a dressing apparatus including a board holder for holding a dresser board, in which the dressing apparatus causes the dresser board held by the board holder and the grindstones to slide abrasively against each other;   grinding the workpiece by the grindstones dressed by using the dressing apparatus or grinding the workpiece by the grindstones while simultaneously the grindstones are being dressed by using the dressing apparatus; and   after the workpiece is ground, dividing the workpiece into device chips, wherein   the grindstones are dressed by using the dressing apparatus by
 measuring a load applied to the dresser board, and 
 pressing the board holder and the grindstones against each other in a direction transverse to a plane along which the grindstones and the dresser board slide abrasively against each other such that the measured load applied to the dresser board has a value falling within a predetermined numerical range. 
   
     
     
         18 . The method according to  claim 17 , wherein the workpiece is divided along division initiating points formed in the workpiece into the device chips.