PRINTED CIRCUIT BOARD RETURN ROUTE CHECK METHOD AND PRINTED CIRCUIT BOARD PATTERN DESIGN CAD DEVICE

摘要

A CAD apparatus for designing patterns of a printed board, includes: a signal wiring pattern detecting unit 22 for detecting a signal wiring pattern with reference to wiring information of the printed board; a guard ground detecting unit 23 for tracing the signal wiring pattern along the longitudinal direction thereof, to detect whether or not a guard ground exists within a distance from the signal wiring pattern to a predetermined first discriminant value GL, and for identifying a non-guard ground section in which no guard ground exists within the distance to the first discriminant value GL, and for detecting whether or not a guard ground exists within another distance from the signal wiring pattern to a second discriminant value GU, which is larger than the first discriminant value GL, in the non-guard ground section; and a return path judging unit 25 for judging an error of guard ground when no guard ground exists within the distance to the second discriminant value GU in the non-guard ground section, thereby quickly checking a return path without mistake.