WIRING METHOD FOR MULTILAYER INTERCONNECTION BOARD

PURPOSE:To improve degree of freedom of providing channels and improve a wiring capacity, by fretting, a second wiring pattern led from some pads, inside the region occupied by the parts mounted on a top face, when the arranging direction of the pads coincides with the traveling direction of a first wiring pattern, and by performing a multilayer wiring through several via holes. CONSTITUTION:The pattern of lead wires, led from a group of pads included in a pad group region 7 which are arranged in the same direction as the traveling direction of a main wiring pattern, is fretted in a pattern fretting region 9. The pattern fretting region 9 is the region surrounded by the pad group region 7 and a pad group region 8, i.e., the region existing inside the region occupied by the parts mounted on a top face. Moreover, the layer including the pattern fretting region 9 is not limited to the uppermost layer. By using several lower layers too, the pattern of lead wires can be fretted through several via holes. Therefore, the fretting region of a pattern 5 of lead wires led from a group 1 of pads, which are arranged in the same direction as the traveling direction of the main wiring pattern, can be set inside the region occupied by the parts mounted on the top face.