BigPatents India

An electret condenser microphone includes a case having a bottom provided with sound holes, a diaphragm electrically connected to the case and vibrated in accordance with sound pressure introduced through the sound holes, a fixed electrode plate disposed opposing the diaphragm with a spacer interposed therebetween. the fixed electrode plate being formed of a metal plate coated with a polymer film on which an electret is formed, an insulating ring for insulating the fixed electrode plate from the case. a printed circuit board in which a circuit component is embedded, the printed circuit board defining a back chamber with the fixed electrode plate, and an integrated base for supporting the fixed electrode plate and the printed circuit board and electrically connecting the fixed electrode plate to the circuit component embedded in the printed circuit board through a connecting terminal. The integrated base inc1udes a hollow cylindrical insulating body having a top and a bottom. and first and second metal plating layers formed on the top and bottom of the hollow cylindrical insulating body. respectively. Outer diameters of the first and second metal plating layers are less than that of the insulating body and the first and second metal plating layers being conducted each other by a conductor. (FIG.1).