PURPOSE: To obtain a lead frame having a function of high-sealing reliability by joining the lead frame and plastics through glass layers formed on both surfaces of the inner lead section of the lead frame in a plastic seal type IC.

CONSTITUTION: Bondability among a sealing resin 12 and lead frames 11 is improved by forming thin layers consisting of glass coatings 14 on both surfaces of inner lead sections 13 as sealing sections with plastics 12 of the lead frames 11, and the intrusion of moisture into a package from a joining interface is prevented. The glass layers 14 are used in order to improve bond-ability because glass has excellent adhesive properties with epoxy resin as the sealing resin and a Fe- Ni alloy (such as 42 alloy) or a copper alloy employed as the lead frames. Since variance under the state of oxidation of the surfaces of the lead frames due to chip bonding and wire bonding processes is eliminated and the properties of the surface are made constant at all times, a matching with the conditions of sealing is facilitated, and a leakage path is shortened particularly.