PURPOSE: To diminish a bonding defect, by forming a step part on the surface of a bonding part at an end of an inner lead and by fitting a mounter head to the projected part while a semiconductor device is stuck to the rear side of a tape.

CONSTITUTION: An insulating tape 5 is stuck to the rear side of an inner lead 2 in an LOC(Lead On Chip) lead frame. In the lead frame assembly, a step part is provided on the surface of a bonding part 3 located at an end of the inner lead 2. Namely, a projected part 4 is formed at an end of the bonding part 3 for making the step part. Then, when a mounter head is used for pressing the inner lead onto a semiconductor device and the tape is bonded by compression with a semiconductor device, the mounter head is contacted with the projected part 4 so that the bonding is carried out with a bonding part 3 other than the projected part 4. By this means, there are no flaw, flaking off or defect due to attaching foreign matter of the inner lead 2.