Fabrication method of semiconductor integrated circuit device

A method of manufacturing a semiconductor device comprising the steps of:

• (a) preparing a printed circuit board having a first surface and a second surface which is opposite to said first surface, said printed circuit board having a plurality of chip device forming regions on said first surface;
• (b) mounting a plurality of semiconductor chips on said plurality of chip device forming regions respectively;
• (c) disposing said printed circuit board together with said plurality of semiconductor chips at a mold such that said plurality of semiconductor chips are in a cavity defined by an upper mold part and a lower mold part of said mold, and such that said printed circuit board is clamped by said upper and lower mold parts;
• (d) setting depths of air vents communicating with said cavity of said mold to a value by a movable air vent portion due to a thickness of said printed circuit board;
• (e) after the step (d), injecting a resin material in said cavity to form a resin body sealing said plurality of semiconductor chips;
• and
• (f) after the step (d), dividing said printed circuit board into pieces corresponding to said plurality of chip device forming regions.