PRE-PLATED LEADFRAME FOR SEMICONDUCTOR PACKAGE AND PRE-PLATING METHOD TO AVOID CRACK OF OUTER LEAD AND SHORT-CIRCUIT PHENOMENON OF LEADFRAME CAUSED BY WHISKER

摘要

PURPOSE: A pre-plated leadframe for a semiconductor package is provided to avoid a crack of an outer lead and a short circuit of a leadframe caused by whisker by maintaining a relatively high composition ratio of an alloy element in a tin plate layer adjacent to a metal base material. CONSTITUTION: A metal base material for a leadframe has portions corresponding to inner leads(22) and outer leads(23). A tin plate layer(32) is formed in the portion of the metal base material corresponding to the outer leads by using a tin alloy. The alloy element included in the tin plate layer has a consecutive concentration gradient. The density of the alloy element decreases consecutively as it goes to the outside.