Cutter wheel for brittle sheets

#1. Field of the Invention

#The present invention relates to a cutter wheel for forming scribe lines to cut a brittle sheet such as a semiconductor wafer, a glass plate or a ceramic plate.

#2. Description of Prior Art

#These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, and in which:

#FIGS. 1A and 1B are a side view and a sectional view of a cutter wheel of an embodiment;

#FIGS. 2A, 2B and 2C are sectional views of grooves of cutter wheels;

#Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, FIG. 1A is a side view of a cutter wheel 1a according to an embodiment of the invention, and FIG. 1B is a sectional view along line A—A in FIG. 1A. The cutter wheel 1a has a disk with two side planes, and it has a circumference with a generally V-shaped edge and a shaft hole 2 at the center thereof into which a rotation shaft for the cutter wheel 1a is inserted. Thus, the wheel 1a has an outer diameter and an inner diameter. Further, at the inner peripheral plane of the shaft hole 2, eight grooves 3a (represented by solid lines) of a predetermined length are formed with an equal circumferential distance between them and along the axial direction (or a direction of the thickness of the wheel) extending from a first side plane to a second one. On the other hand, eight additional grooves 3a (represented as dashed lines) of the predetermined length are similarly formed at an equal circumferential distance between them and extending in the opposite axial direction from the second side plane to the first one. In FIG. 1A, the first grooves 3a represented as solid lines and the second grooves 3a represented as dashed lines observed from the first side plane of the wheel are located in a state having inverted phases between them. That is, a first groove 3a is located at the center between two second grooves, or vise versa, when observed from a side plane of the wheel. The depth of the grooves 3a in the radial direction decreases from the surface of the side plane to the inside thereof.

#The grooves 3a, as observed along section C—C of FIG. 1A, have a U-character shape as shown in FIG. 2A. However, they may have a V-character-like shape as shown in FIG. 2B or a rectangular shape as shown in FIG. 2C. The grooves of different shapes may have similar functions and advantages.

#The width of the groove 3a is, for example, {fraction (1/48)} to ½ of the circumference of the shaft hole 2, depending on the outer diameter of the cutter wheel 1a. The depth (T) of the groove 3a in the radial direction from the axial center of the cutter wheel is selected so that {fraction (1/20)}<T/S<1 wherein S denotes a difference between the outer radius and the inner radius of the cutter wheel.