A chronological review of production and applications of electret condenser microphone for consumer use

Mass production of electret condenser microphones (ECM) built into compact cassette tape recorders for consumer use started in 1970. The key issues were the FEP electret foil and the integrated circuit including FET and resistor. The production grew according to progress of applications which was widened to stereo equipments and to communication equipments. Materials and fabricating technologies have coped with the demands due to increasing quantity and diversifying requirements. The microphones have changed to smaller size and directional characteristics. The present dominant requirement is for higher temperature specifications for automated assembly systems.