(a) providing a work substrate having a resin substrate and metal plates having rigidity equal to or higher than 100 GPa and formed on both surfaces of the resin substrate;

(b) removing an inner portion of each of the metal plates, corresponding to a product part which enables a plurality of unit printed circuit boards to be integrally connected to each other, through etching, thus simultaneously exposing the resin substrate of the product part and forming a dummy metal frame enclosing an outer periphery of the product part;

(c) forming through holes in the resin substrate of the product part;

(d) forming an inner circuit pattern on the resin substrate of the product part having the through holes;

(e) forming an insulating layer on the product part having the inner circuit pattern;

(f) forming via holes in the insulating layer;

(g) forming an outer circuit pattern on the insulating layer having the via holes; and

(h) forming a solder resist layer on the product part having the outer circuit pattern, and then exposing portions of the circuit pattern, corresponding to a bump pad for semiconductor mounting and a soldering pad for connection with an external component, through solder opening.