Semiconductor package having a die pad with downward extended tabs

Abstract

A semiconductor package having a lead frame formed with a die pad and a plurality of conductive leads, wherein the die pad is formed with a plurality of tabs to impede the resin flow below the die pad such that a downward pressure is produced because the resin flow above the die pad moves at a speed faster than that below the die pad. As a result, the tab is urged against a bottom surface of a mold cavity during a transfer molding process so as to prevent the die pad from being exposed to an encapsulant for encapsulating the die pad and a semiconductor die mounted on the die pad.

What is claimed is:  
     
         1 . A semiconductor package comprising: 
 a semiconductor chip;    a lead frame having a die pad for bearing the semiconductor chip and a plurality of leads for electrically coupling to the semiconductor die, wherein the die pad is formed with a plurality of tabs downwardly extending from the plane of the die pad; and    an encapsulant for encapsulating the semiconductor chip, die pad, and inner portions of the leads.    
     
     
         2 . The semiconductor package of  claim 1 , wherein the leads are electrically coupled to the semiconductor chip by bonding wires.  
     
     
         3 . The semiconductor package of  claim 1 , wherein the tab has a height not more than the distance between a bottom surface of the die pad and a surface, facing the bottom surface of the die pad, of a mold cavity of an encapsulating mold used for a transfer molding.  
     
     
         4 . The semiconductor package of  claim 1 , wherein the tab has a height slightly higher than the distance between a bottom surface of the die pad and a surface, facing the bottom surface of the die pad, of a mold cavity of an encapsulating mold used for a transfer molding.  
     
     
         5 . The semiconductor package of  claim 1 , wherein the tab is formed on the die pad by punching.  
     
     
         6 . The semiconductor package of  claim 1 , wherein the tab is formed on the die pad by etching.  
     
     
         7 . The semiconductor package of  claim 1 , wherein the die pad has at least one opening formed in the center.  
     
     
         8 . The semiconductor package of  claim 1 , wherein the tab is integrally formed with the die pad.  
     
     
         9 . The semiconductor package of  claim 1 , wherein the die pad is positioned in the plane of the leads.  
     
     
         10 . The semiconductor package of  claim 1 , wherein the die pad is downset from the plane of the leads.