Semiconductor device with wire including a surface metal layer covering a core metal

A semiconductor device comprising:

• a first circuit including a first semiconductor element;
• a second circuit including a third semiconductor element;
• a second semiconductor element that is electrically connected to each of the first semiconductor element and the third semiconductor element, the second semiconductor element relaying a mutual signal between the first circuit and the second circuit and insulating the first circuit and the second circuit from each other;
• a first terminal lead electrically connected to the first semiconductor element and included in the first circuit;
• a second terminal lead electrically connected to the third semiconductor element and included in the second circuit;
• a first wire connected to the first semiconductor element and the second semiconductor element and included in the first circuit;
• a second wire connected to the first semiconductor element and the first terminal lead and included in the first circuit;
• a third wire connected to the second semiconductor element and the third semiconductor element and included in the second circuit;
• a fourth wire connected to the third semiconductor element and the second terminal lead and included in the second circuit;
• and
• a sealing resin covering the first semiconductor element, the second semiconductor element, the third semiconductor element, the first wire, the second wire, the third wire and the fourth wire,
• wherein an electric potential of the second circuit is higher than an electric potential of the first circuit,
• each of the first wire and the third wire contains a first metal,
• the second wire includes a first core containing a second metal, and a first surface layer containing a third metal and covering the first core,
• the fourth wire includes a second core containing the second metal, and a second surface layer containing the third metal and covering the second core,
• an atomic number of the second metal is smaller than an atomic number of the first metal, and
• the third metal has a greater bonding strength with respect to each of the first terminal lead and the second terminal lead than the second metal.