a printed circuit device including semiconductor ic chips on the surface of a printed circuit board made of insulating material . the printed circuit board includes on the surface thereof semiconductor mounting regions and conductive layers . the semiconductor ic chips are respectively fixedly mounted on the semiconductor element mounting regions disposed on the printed circuit board . thin metal wires interconnect electrodes of the ic chips with the conductive layers . a sealing cover plate having a plurality of recesses formed therein is fixedly mounted onto the surface of the printed circuit board with adhesive for hermetically sealing each of the ic chips and electric wires with a respective one of the recesses in the cover plate . the cover plate can comprise a composite of a thermoplastic resin material layer and a metal layer , such as aluminum or an aluminum alloy .