Flip chip package

Abstract

A flip chip package structure is provided. A chip is electrically connected to a substrate. A heat sink is attached to the backside of the chip. The heat sink has at least a through hole located at a peripheral region and laterally adjacent to the chip. A dispensing process is carried out to deliver an underfill material via the through hole such that the space between the chip and the substrate is filled. The underfill material also extends to cover a portion of the heat sink so that the heat sink and the substrate are connected together. The underfill material is cured to fix the heat sink, the substrate and the chip in position.

1 . A flip chip package structure, comprising: 
 a chip having an active surface and a corresponding backside, wherein the active surface comprises a plurality of bumps thereon;    a substrate, wherein the substrate is connected to the active surface of the chip through the bumps;    a heat sink attached to the backside of the chip, wherein the heat sink comprises at least a through hole located outside a perimeter of the chip; and    an underfill material that fills up a space between the active surface of the chip and the substrate and connects the heat sink and the substrate.    
     
     
         2 . The flip chip package structure of  claim 1 , wherein the through hole is positioned outside the perimeter and adjacent to the chip.  
     
     
         3 . The flip chip package structure of  claim 1 , wherein the heat sink has a coefficient of thermal expansion comparable to the substrate.  
     
     
         4 . The flip chip package structure of  claim 1 , wherein the heat sink has an upper surface and a lower surface, and wherein the lower surface further comprises at least a stopper on an outer edge of the through hole.  
     
     
         5 . The flip chip package structure of  claim 1 , further comprising a thermal conductive layer between the backside of the chip and the heat sink.  
     
     
         6 . The flip chip package structure of  claim 1 , wherein the underfill material comprises an epoxy resin.  
     
     
         7 . The flip chip package structure of  claim 6 , wherein the epoxy resin comprises a thermal-setting epoxy resin.  
     
     
         8 . The flip chip package structure of  claim 4 , wherein the stopper is downward protruded from the lower surface of the heat sink.  
     
     
         9 . The flip chip package structure of  claim 4 , wherein the stopper is located outside the perimeter of the chip.  
     
     
         10 . The flip chip package structure of  claim 1 , further comprising a stiffener connecting the substrate and the heat sink.  
     
     
         11 . The flip chip package structure of  claim 1 , wherein the underfill material fills the through hole.  
     
     
         12 . The flip chip package structure of  claim 1 , wherein the heat sink contacts with the substrate.