Patent ID: 7345246

Claim:
A wiring board, comprising: a board core comprising a main core body of a plate-like shape and comprised of a macromolecular material, and a sub-core portion, the main core body including, formed therein, a sub-core housing portion which is open at at least one end, the sub-core portion being of a plate-like shape and comprising a material with a smaller linear coefficient of expansion than that of the main core body, said sub-core portion being housed in the sub-core housing portion and having a thickness matched to that of the main core body; a filling coupled portion, comprised of a macromolecular material, disposed in, and filling, a gap between an inner peripheral surface of the sub-core housing portion and an outer peripheral surface of the sub-core portion; a first terminal array formed on a first main surface of the board core and comprised of a first side first type terminal and a first side second type terminal, one said terminal serving as a power source terminal and the other said terminal serving as a ground terminal, and said first terminal array further including a first side signal terminal; and a second terminal array formed on a second main surface of the board core and comprised of a second side first type terminal and a second side second type terminal which are conductively connected to the first side first type terminal and the first side second type terminal, respectively, and a second side signal terminal which is conductively connected to the first side signal terminal; the first terminal array being disposed in a position wherein the first terminal array overlaps a resultant projected area of the sub-core portion produced by an orthogonal geometric projection of the sub-core portion onto a reference surface parallel to a planar surface of the board core; and the sub-core housing portion having an inner peripheral edge of a cross section, in a plane parallel to a planar surface of the sub-core portion, of a quadrate shape with four corners, and having at the corners thereof one of (i) a radius portion and (ii) a chamfered portion, with a dimension of between 0.1 mm and 2 mm.