Semiconductor package having exterior plating films formed over surfaces of outer leads

Abstract

A semiconductor device having an improved whisker resistance in an exterior plating film is disclosed. The semiconductor device includes a tab with a semiconductor chip fixed thereto, plural inner leads, plural outer leads formed integrally with the inner leads, a plurality of wires for coupling electrode pads of the semiconductor chip and the inner leads with each other, and a sealing body for sealing the semiconductor chip. The outer leads project from the sealing body and an exterior plating film, which is a lead-free plating film, is formed on a surface of each of the outer leads. In the exterior plating film, the number of grains not larger than 1 μm in diameter and present on an interface side in the thickness direction of the exterior plating film is larger than the number of grains not larger than 1 μm and present on a surface side of the exterior plating film, whereby the difference in linear expansion coefficient between the exterior plating film and the outer lead is made small, thus making it possible to suppress the growth of whisker.