Four-sided lead edge flat package. One of the surface mount packages, the pins are led out from four sides in a seagull wing (L) shape. There are three kinds of substrates: ceramic, metal and plastic. In terms of quantity, plastic packaging accounts for the vast majority. When the material is not specifically indicated, it is plastic QFP in most cases. Plastic QFP is the most popular multi-pin LSI package. Not only used in digital logic LSI circuits such as microprocessors and door displays, but also in analog LSL circuits such as VIR signal processing and audio signal processing.