MANUFACTURING METHOD FOR LEAD FRAME

PROBLEM TO BE SOLVED: To provide a press-mark method capable of decreasing a sag occurring at punching for a reliable lead frame, related to manufacturing of a lead frame coping with higher integration and miniaturization by the press-working. SOLUTION: A lead frame is provided by press-working which comprises a plurality of inner leads so radially extending as to enclose a semiconductor chip mounting part and an outer lead extending through a dam-bar. Here, at least an inner lead root part and the vicinity of dam-bar are punched with a smaller punch so that the punching position in the inner lead direction is inside a mold line, then the inner lead, the dam-bar, and the outer lead are punched.