Patent US 5,315,535

In an automatic router for use in automatically designing wiring paths among connection elements, such as via holes, terminals, on a wiring board, connection failures are previously detected by a connection failure detecting portion. Provisional wiring paths are successively selected by a path searching portion with reference to the connection failures to decide a new wiring path. The new wiring path is inserted among existing wiring paths by moving adjacent ones of the existing wiring paths in a predetermined direction. The connection failures may be specified, for example, by channel failures which appear when any wiring paths can fail to be arranged between the connection elements or by terminal network data signals produced on superposition of coordinate components of adjacent ones of the via holes.