Abstract: A lead frame includes a base, a substantially rectangular device hole formed in the base, an island formed in the device hole and offset a predetermined distance from the base, a plurality of inner leads arranged at predetermined intervals to extend toward a pair of opposing edges of the island, and suspension pins formed to extend toward a pair of edges of the island not opposing the end portions of the inner leads. The island is used to mount a semiconductor chip, and the suspension pins connect the island and the base. A pair of dummy leads extended from the base toward the island is formed on the both sides of at least one suspension pin. The distance from the side edge of the suspension pin to the side edge of the dummy lead is equal to or smaller than the distance from the end portions of the inner leads to the side edge of the island.

Abstract: A method and apparatus for determining the thickness of at least one layer superimposed on a substrate, at least one of the layers or the substrate being a conductor of electricity. The method includes the steps of generating an electromagnetic alternating field in the vicinity of the outer most layer with a coil in order to cause any currents to be generated in the conductor which act upon the alternating field. The frequency of the alternating field is adjusted to at least two different frequencies and is measured at these frequencies. The thickness of the layers is then determined based on the measurements and the electromagnetic properties of the substrate and the layers.