Abstract: A method for producing a completed base cap for a plastic package sealing a semi-conductor therein includes the steps of forming the initial body of a plastic base cap including a centrally located hollow recess on one side thereof, placing lead frames on said base cap body in such a manner that the terminal end portions of said individual leads rest on the peripheral land of said base cap body surrounding said central recess, and forming outer side sections to the base cap including a step shoulder on the top side thereof by molding the same integrally with said lead frame and said initial body such that an intermediate portion of each of said leads adjacent their inner terminal end portions is embedded within said outer side sections of the base cap. A liquid honing step is provided on the base cap shoulder after the formation thereof, and to the inner terminal end portions of the leads.

Abstract: The external lead frame for a plastic sealed, cavity molded type semi-conductor device is formed of Phospor bronze, with the bronze lead frame liquid honed, it is pre-heated and supported in a mold cavity so as to be embedded into a powder epoxy resin molded header with improved sealing between the Phospor bronze lead frame in the header molded thereabove.