Production of semiconductor device

The method of easily producing a semiconductor device having multitude of pins, high reliability and where external connection terminals can be arranged with a high density, comprises the steps of: forming a recess (52) on one side of the metal substrate (40); forming a metal film (46), made of a metal that is not dissolved by an etchant solution which dissolves the metal substrate (40), on the inner surface of the recess (52); punch-pressing a region of the metal substrate (40) that corresponds to one region of the metal film (46) from the other side of the metal substrate (40) so that the region of the metal film formed on the bottom face of the recess (52) becomes substantially flush with the said one side of the metal substrate (40), thereby to form the bonding pad (42a) from an extending portion of the metal film that extends from the bottom face of the recess (52) over the surface of the metal substrate; mounting a semiconductor chip (10) on said one side of the metal substrate (40) whereon the bonding pad (42a) is formed; wire-bonding (20) the electrodes of the semiconductor chip and the bonding pads (42a); sealing with resin (12) said one side of the metal substrate that includes the semiconductor chip (10), the bonding wire (20), and the metal film (46); and dissolving and removing the metal substrate (40) by etching thereby to expose the metal film (46) formed on the inner surface of the recess.