A lead frame strip has a plurality of unit lead frames. Each of the unit lead frames has a periphery structure connecting adjacent ones of the unit lead frames, a die paddle inside of the periphery structure, a plurality of leads connected to the periphery structure and extending towards the die paddle, and a molding compound channel in the periphery structure configured to guide liquefied molding material. The lead frame strip is processed by attaching a semiconductor die to each of the die paddles, electrically connecting each of the semiconductor dies to the leads, and forming a liquefied molding compound on each of the unit lead frames. The liquefied molding compound is formed such that the liquefied molding compound encapsulates the semiconductor dies and flows into the molding compound channels thereby forming molding extensions that extend onto the periphery structures.