Patent ID: 7523846

Claim:
A scribing method using a brittle material separation disk-shaped wheel having a central portion in a thickness direction protruding in a circumferential direction so as to form a blade edge at an edge line portion of the wheel, wherein the edge line portion of the disk-shaped wheel comprises at least one region (A) and at least one region (B), region (A) is a region where a plurality of grooves having a predetermined shape are formed in the edge line portion with a predetermined pitch, while region (B) is a region where grooves are not formed in the edge line portion, and in the brittle material separation disk-shaped wheel the ratio of a length of a region occupied by the plurality of grooves with respect to an entire perimeter of the edge line portion is equal to or smaller than ¾, comprising performing scribing along a scribe line on a brittle material using the wheel to form a vertical crack in the brittle material that varies periodically in depth along the scribe line without extending through the brittle material, wherein the scribe line is formed on the glass substrate, and the vertical crack is extended by applying a force to widen horizontally the vertical crack, the vertical crack being formed along the vertical direction of the scribe line on the glass substrate; and wherein the depth of the vertical crack is periodically varied according to the depth of the plurality of grooves under a constant load.