Method of Manufacturing a Semiconductor Device

Abstract

The quality of a non-leaded semiconductor device is to be improved. The semiconductor device comprises a sealing body for sealing a semiconductor chip with resin, a tab disposed in the interior of the sealing body, suspension leads for supporting the tab, plural leads having respective to-be-connected surfaces exposed to outer edge portions of a back surface of the sealing body, and plural wires for connecting pads formed on the semiconductor chip and the leads with each other. End portions of the suspending leads positioned in an outer periphery portion of the sealing body are not exposed to the back surface of the sealing body, but are covered with the sealing body. Therefore, stand-off portions of the suspending leads are not formed in resin molding. Accordingly, when cutting the suspending leads, corner portions of the back surface of the sealing body can be supported by a flat portion of a holder portion in a cutting die which flat portion has an area sufficiently wider than a cutting allowance of the suspending leads, whereby it is possible to prevent chipping of the resin and improve the quality of the semiconductor device (QFN).

1 . A semiconductor device comprising: 
 a semiconductor chip having a main surface, a back surface, a semiconductor element and a plurality of electrodes, the semiconductor element and the plural electrodes being formed over the main surface of the semiconductor chip;    a sealing body for sealing the semiconductor chip with resin;    a chip mounting portion disposed in the interior of the sealing body and connected to the semiconductor chip;    suspending leads for supporting the chip mounting portion;    a plurality of leads exposed partially to outer edge portions of a back surface of the sealing body and arranged side by side in the outer edge portions; and    a plurality of wires for connecting the plural electrodes of the semiconductor chip and the plural leads corresponding thereto with each other,    wherein end portions of the suspending leads positioned in an outer periphery portion of the sealing body are covered with the sealing body on the back surface side of the sealing body.    
     
     
         2 . A semiconductor device according to  claim 1 , wherein a projecting portion is formed over a back surface opposite to the chip mounting side of the chip mounting portion, the projecting portion being exposed to the back surface of the sealing body.  
     
     
         3 . A semiconductor device according to  claim 1 , wherein projecting portions are formed over back surfaces opposite to the chip mounting side of the suspending leads, the projecting portions being exposed to the back surface of the sealing body.  
     
     
         4 . A semiconductor device according to  claim 1 , wherein a projecting portion is formed centrally of a back surface opposite to the chip mounting side of the chip mounting portion, and projecting portions are formed over back surfaces opposite to the chip mounting side of the suspending leads, the projecting portions of the chip mounting portion and the suspending leads being exposed to the back surface of the sealing body.  
     
     
         5 . A semiconductor device according to  claim 1 , wherein a projecting portion is formed over a back surface opposite to the chip mounting side of the chip mounting portion, and projecting portions are formed over back surfaces opposite to the chip mounting side of the suspending leads at positions corresponding to corner portions of the semiconductor chip, the projecting portions of the chip mounting portion and the suspending leads being opposed to the back surface of the sealing body.  
     
     
         6 . A semiconductor device according to  claim 1 , wherein a plurality of projecting portions are formed over a back surface opposite to the chip mounting side of the chip mounting portion, and projecting portions are formed over back surfaces opposite to the chip mounting side of the suspending leads, the projecting portions of the chip mounting portion and the suspending leads being exposed to the back surface of the sealing body.  
     
     
         7 . A semiconductor device according to  claim 6 , wherein the chip mounting portion and the suspending leads are half-etched in other areas than the respective projecting portions.  
     
     
         8 . A semiconductor device according to  claim 1 , wherein back surfaces opposite to the chip mounting side of the suspending leads are covered with the sealing body and not exposed to the back surface of the sealing body.  
     
     
         9 . A semiconductor device according to  claim 1 , wherein the area of the chip mounting portion is smaller than the area of the semiconductor chip.  
     
     
         10 . A method of manufacturing a semiconductor device, comprising the steps of: 
 (a) providing a lead frame, the lead frame including a chip mounting portion, a plurality of leads arranged around the chip mounting portion, and suspending leads for supporting the chip mounting portion;    (b) mounting a semiconductor chip over the chip mounting portion;    (c) connecting electrodes formed over the semiconductor chip and the leads corresponding thereto with each other through wires;    (d) disposing the lead frame over a sealing sheet disposed over a die surface of a resin molding die, thereafter clamping the resin molding die in such a manner that the plural leads of the lead frame come into close contact with the sealing sheet, then sealing the semiconductor chip and the wires with a sealing resin to form a sealing body in such a manner that the sealing resin is allowed to lap over back surfaces of the chip mounting portion and the suspending leads and portions of the back surfaces of the suspending leads corresponding to outer edge portions of the sealing body are covered with the sealing body; and    (e) separating the leads and the suspending leads from the lead frame.    
     
     
         11 . A method according to  claim 10 , wherein the sealing with the sealing resin is carried out by injecting the sealing resin into a cavity of the resin molding die in the step (d) in such a manner that the sealing resin is injected into the cavity through gaps each corresponding to the thickness of each of the leads and formed on both sides of each of the suspending leads while pressing down the outside of an end portion of the suspending lead by a gate portion of the resin molding die.  
     
     
         12 . (canceled)  
     
     
         13 . (canceled)  
     
     
         14 . A semiconductor device comprising: 
 a lead frame, the lead frame including a chip mounting portion, suspending leads connected to the chip mounting portion, and a plurality of leads arranged around the chip mounting portion;    a semiconductor chip disposed over the chip mounting portion, the semiconductor chip including a plurality of semiconductor elements and a plurality of electrodes;    a plurality of wires for electrically connecting the plural electrodes of the semiconductor chip and the plural leads with each other; and    a resin body for sealing the semiconductor chip, the chip mounting portion, the plural wires and the plural leads, the resin body having a surface, a back surface opposite to the surface and side faces located between the surface and the back surface;    wherein one end portions of the plural leads are exposed from the back surface of the resin body,    wherein at the side faces of the resin body the plural leads and the suspending leads have cut surfaces created by cutting the lead frame, and    wherein the cut surfaces of the suspending leads do not reach the back surface of the resin body.    
     
     
         15 . A semiconductor device according to  claim 14 , wherein the length of the cut surface of each of the suspending leads in the thickness direction of the resin body is shorter than the length of the cut surface of each of the plural leads in the thickness direction of the resin body.