A semiconductor device is provided that includes a substrate having a first side, a second side, and a through-hole. An external connection terminal is located on the first side of the substrate, and a chip connection terminal is located on the second side of the substrate. The chip connection terminal is electrically connected to the external connection terminal via the through-hole. In one preferred embodiment, the external connection terminal, the inner portion of the through hole, and a first portion of the chip connection terminal have a hard gold plating, and a second portion of the chip connection terminal has a soft gold plating. In another preferred embodiment, the chip connection terminal, the inner portion of the through hole, and a first portion of the external connection terminal have a soft plating, and a second portion of the external connection terminal has a hard gold plating. Thus, in the present invention, there is no plating boundary located within the through-hole, so the reliability of the interconnection that passes through the through-hole is improved. The present invention also provides a method of manufacturing such a device.