Semiconductor device, substrate for producing semiconductor device and method of producing them

A method of producing a substrate for use in production of a semiconductor device, comprising the steps of:

• preparing a metal foil;
• providing partially plating layers to portions corresponding to each electrically conductive portion of the metal foil as well as to a portion corresponding to a die pad of the metal foil;
• attaching the bottom face of the metal foil having the partially plating layers formed thereon to an adhesive layer side of an adhesive sheet having a base layer and the adhesive layer;
• forming electrically conductive portions by etching the metal foil using each partially plating layer as a resist, each electrically conductive portion including a metal foil and electrically conductive portion plating layers provided on both upper and lower ends of the metal foil, and
• forming a die pad having a die pad plating layer provided on the same plane as the lower electrically conductive portion plating layer of each electrically conductive portion;
• loading a semiconductor element having electrodes on the die pad, the die pad including a bank portion that has a concave portion formed therein, the bank portion being formed as a continuous portion so as to surround the semiconductor element as viewed from a top of the semiconductor device, and the bank portion including a metal foil and both upper and lower plating layers;
• and
• determining an outer shape of the adhesive sheet by processing the adhesive sheet, wherein
• the concave portion serves to receive the semiconductor element therein, and
• central portions of the metal foil in each of the electrically conductive portions and the bank portion are narrowed relative to both the upper and lower electrically conductive portion plating layers.