Abrasive blade having a polycrystalline ceramic core

#1. Field of the Invention

#This invention relates to abrasive cutting blades having a polycrystalline structural ceramic core, which are useful in the cutting or dicing of silicon wafers and other hard, and/or brittle materials. The cutting discs of this invention are particularly useful in the die-separation phase of the production of semi-conductor chips, magnetic heads and other components for use in the electronics industry.

#2. Description of the Prior Art

#The above and other objects and the attendant advantages of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

#FIG. 1 is a plan view of a resin-bonded abrasive blade of the prior art.

#FIG. 2 is a section of FIG. 1 taken along line A--A.

#This invention will be described by reference to the drawings. FIG. 3 is a plan view of the cutting blade of this invention. Core 4 is an annular disc formed from a low porosity, polycrystalline structural ceramic. An abrasive matrix 5 is firmly adhered to the circumference of disc 4. Hole 6 is provided for mounting to a flange and/or spindle. FIG. 4 is a cross-section of the abrasive cutting blade of this invention showing the comparative widths of the core and abrasive matrix.

#FIG. 1 is a plan view of the prior art showing disc 1, abrasive 2 and mounting hole 3. FIG. 2 is a cross-section of the blade of FIG. 1, showing the relative widths of the disc and abrasive matrix. As can readily be seen from the comparison of FIGS. 2 and 4, applicants' blade has a cutting edge which is wider than the disc.

#FIG. 5 is a cross-sectional view of the cutting blade of this invention mounted upon a flange or spacer 7. A shaft or arbor 8 passes through the blade and flange. A flange is normally used when a single blade is used. Spacers or multiple flanges are used when a number of blades are ganged so that the multiple cuts may be made in the substrate. The exposure of the blade is defined as the distance from the circumference of the flange or spacer to the edge of the blade 5. The flange or spacer is required to maintain rigidity of the blade, especially very thin blades, and the wobble or run-out of a cutting blade is inversely proportional to the exposure. For a given exposure, run-out is proportional to the rigidity of the exposed portion of the blade.