Patent ID: 8057723

Claim:
A method of manufacturing an insert-molded article comprising providing a manufacturing apparatus containing a lead frame in which a metal component is supported by tie bars, the manufacturing apparatus comprising: a first mold part; a second mold part combined with the first mold part to define a cavity and being separatable from the first mold part; pilot pins provided to the first mold for positioning the lead frame; the lead frame with tie bars disposed in the cavity resting on the first mold part; said tie bars having easily breakable low-strength portions which are notches or slits extending into the depth of the tie bars at the boundaries between the tie bars and the metal component, wherein the lead frame, metal component and tie bars have a common plane and the easily breakable low-strength portions extend perpendicularly to the common plane; and punches provided to the second mold for separating the tie bars from the metal component disposed to press against the tie bars in order to break the low-strength portions below the common plane to form a gap between the inner surfaces of the tie bar cutting punches and the cut planes of the tie bars, the punches being disposed so as to form the side walls of the cavity and the punches being disposed to be offset from the low-strength portions such that the innermost surface of the punches are further from the center of the apparatus than the low-strength portions, operating the tie bar cutting punches to break the low-strength portions below the common plane and separate the tie bars from the metal component, introducing molding resin around the metal component in the cavity such that the cut planes of the tie bars are buried in resin.