STRUCTURE OF RAW MATERIAL SUBSTRATE USED TO MANUFACTURE INSULATING SUBSTRATE IN LINE HEATING BODY

摘要

PROBLEM TO BE SOLVED: To reliably crack the insulating substrate at an abnormal high temperature in a state of being not easily broken at handling time when manufacturing the insulating substrate by breaking a raw material substrate along scribe wires in a line heating body by forming a heating resistance film in a line shape on a slender paper strip-like insulating substrate. SOLUTION: The scribe wires 4 are constituted by carving the recessed parts 3 having the proper depth by irradiation of a laser beam in large numbers side by side in a row at a constant pitch interval along the boundary line, and in the middle of these scribe wires 4, the part by narrowing a pitch interval of the respective recessed parts 3 is arranged in the part of the proper length L' or the part by deepening the depth of the respective recessed parts 3 is arranged in the part of the proper length La'.