A semiconductor device of the ball grid array (BGA) type, the device having an electrode, and a process of forming the electrode are disclosed. The electrode includes an insulating film, a seed layer on the insulating film, a mound metal on the insulating film and an interconnection on the seed layer. The mound metal surrounds the seed layer without forming any gap therebetween. The interconnection, which is formed by electroless plating, is apart from the insulating film with the mound metal as an extension barrier for the plating.