Pads are normally distributed around the edge of the IC. The pad should be large enough to have input or output circuitry. Figure below shows the pad frame. Here, the pad is built to a standard width and height. The pad has large VDD and ground lines. The pad includes large piece of metal. If the pad requires external circuitry, it is usually put on the side of the pad closest to the IC core. The IC core is the middle of the pad ring. The placement of pads around the ring is found in order of pins on the package. The wires to the package should not be crossed without the short¬ing. Therefore, if the package pins are required in a order, the pads must be arranged in the same order. VDD and ground pads are simple to design because they require no circuitry. This kind of pad is bigger than the single wire. Therefore, in this case the current is limited by the wire.
IO Architectures and Pad Design