Semiconductor device having curved leads offset from the center of bonding pads

Abstract

A semiconductor device including: a substrate on which a plurality of leads are formed; and a semiconductor chip mounted on the substrate in such a manner that a surface of the semiconductor chip having a plurality of electrodes faces the substrate. Each of the leads includes a first portion that is bonded to one of the electrodes and a second portion that extends outward from the inner side of a region in the substrate that overlays the semiconductor chip. The second portion is entirely adhered to the substrate and curved.

1 . A method of fabricating a semiconductor device, the method comprising: 
 (a) heating a semiconductor chip and a substrate on which a plurality of leads are provided, the semiconductor chip having a plurality of electrodes;    (b) mounting the semiconductor chip on the substrate in such a manner that each of the leads faces one of the electrodes; and    (c) bonding each of the leads to one of the electrodes,    wherein the substrate is formed of a material having a linear expansion rate that is greater than a linear expansion rate of the semiconductor chip; and    wherein the substrate and the semiconductor chip are each heated in the step (a) at a temperature at which the rates of change of the lengths of the substrate and the semiconductor chip before and after the heating are the same.    
   
   
       2 . A method of fabricating a semiconductor device, the method comprising: 
 (a) heating and expanding a semiconductor chip and a substrate on which a plurality of leads are provided, the semiconductor chip having a plurality of electrodes;    (b) mounting the semiconductor chip on the substrate in such a manner that a first portion of each of the leads faces one of the electrodes;    (c) bonding the first portion to one of the electrodes; and    (d) radiating heat of the semiconductor chip and the substrate and causing the semiconductor chip and the substrate to shrink,    wherein each of the leads includes a second portion that continuously extends outward from the first portion and entirely adhered to the substrate; and    wherein the step (d) includes:    (d 1 ) causing the semiconductor chip to shrink at a shrinkage rate that is greater than a shrinkage rate of the substrate, applying a force of the shrinkage direction to the second portion through the first portion to curve the second portion; and    (d 2 ) causing the substrate to shrink at a shrinkage rate that is greater than a shrinkage rate of the semiconductor chip, applying a force of the shrinkage direction to the second portion that is adhered to the substrate to curve the second portion.    
   
   
       3 . The method of fabricating a semiconductor device as defined in  claim 2 , wherein: 
 the electrodes are arranged along one edge of the semiconductor chip;    the leads are disposed in the step (b) so as to intersect the edge;    a protruding portion is formed in the steps (d 1 ) and (d 2 ) to protrude in a direction parallel to the edge and away from the center of the edge;    the protruding portion includes a first curved portion that extends from the first portion and curves in the protrusion direction of the protruding portion and a second curved portion that curves in a direction back from the protrusion direction;    the first curved portion is formed in the step (d 1 ); and    the second curved portion is formed in the step (d 2 ).    
   
   
       4 . The method of fabricating a semiconductor device as defined in  claim 3 , 
 wherein the first portion facing corresponding one of the electrodes is disposed at a position displaced from the center of the corresponding electrode in a direction parallel to the edge and toward the center of the edge, in the step (b).    
   
   
       5 . The method of fabricating a semiconductor device as defined in  claim 4 , wherein: 
 the first portion is designed beforehand in such a manner that the first portion is disposed at a position displaced from the center of the corresponding electrode in a direction parallel to the edge and toward the center of the edge before the heating; and    the substrate and the semiconductor chip are heated in the step (a) at a temperature at which the rates of change of the lengths of the substrate and the semiconductor chip before and after the heating are the same.    
   
   
       6 . The method of fabricating a semiconductor device as defined in  claim 4 , wherein: 
 the first portion is designed beforehand in such a manner that the centers of the first portion and the corresponding electrode coincide with each other in the widthwise direction before the heating; and    the substrate and the semiconductor chip are each heated in the step (a) at temperatures at which the rates of change of the lengths of the substrate and the semiconductor chip before and after the heating are different, in such a manner that the first portion is disposed at a position displaced from the center of the corresponding electrode in a direction parallel to the edge and toward the center of the edge.