Abstract: A multilayered board data input unit inputs design data of a multilayered circuit board provided with through holes penetrating and mutually connecting solid-layer conductors disposed in a multilayer manner. A limitation rule setting unit sets a limitation rule for limiting the number of solid-layer conductors to be connected to the through holes. A separation processing unit separates connections of the solid-layer conductors to the through holes in the design data based on the limitation rule. At this time, when a solid-layer conductor to be separated from the through holes is selected as a candidate, the separation processing unit determines whether the solid-layer conductor is isolated by separation, when the solid-layer conductor is not isolated, determines isolation, and when the solid-layer conductor is isolated, stops separation.

Abstract: A multilayered board data input unit inputs design data of a multilayered circuit board provided with through holes penetrating and mutually connecting solid-layer conductors disposed in a multilayer manner. A limitation rule setting unit sets a limitation rule for limiting the number of solid-layer conductors to be connected to the through holes. A separation processing unit separates connections of the solid-layer conductors to the through holes in the design data based on the limitation rule. At this time, when a solid-layer conductor to be separated from the through holes is selected as a candidate, the separation processing unit determines whether the solid-layer conductor is isolated by separation, when the solid-layer conductor is not isolated, determines isolation, and when the solid-layer conductor is isolated, stops separation.