Mold with compensating base

Abstract

The bottom mold portion for a transfer molding system is covered with a deformable material. During mold clamping, the deformable material contacts the bottom surface of the packaging substrate on which the integrated circuit die is mounted. Deformation of this relatively soft covering on the bottom mold portion accommodates thickness variations in the packaging substrate, as well as non-planarity of the adhesive layer between the integrated circuit die and packaging substrate in exposed active area integrated circuits.

1 . A mold for use in packaging integrated circuits comprising: 
 an upper mold portion and a lower mold portion adapted to receive an integrated circuit die mounted on an upper surface of a packaging substrate, the upper and lower mold portions contacting upper and lower surfaces of the packaging substrate, respectively, during mold clamping; and    a deformable material on at least a portion of a surface of the lower mold portion contacting the bottom surface of the packaging substrate during mold clamping.    
   
   
       2 . The mold according to  claim 1 , wherein the deformable material deforms during mold clamping to accommodate thickness variations in the packaging substrate.  
   
   
       3 . The mold according to  claim 1 , wherein the deformable material deforms during mold clamping to accommodate non-planarity of an adhesive between the integrated circuit die and the packaging substrate.  
   
   
       4 . The mold according to  claim 1 , wherein the upper mold portion includes a cavity receiving the integrated circuit die, the upper mold portion contacting the upper surface of the packaging substrate around a periphery of the cavity during mold clamping.  
   
   
       5 . The mold according to  claim 4 , wherein the upper mold portion includes a projection having a surface contacting an active area of the integrated circuit die during mold clamping.  
   
   
       6 . The mold according to  claim 5 , wherein the deformable material deforms during mold clamping to accommodate thickness variations in the packaging substrate, non-planarity of an adhesive between the integrated circuit die and the packaging substrate, or both.  
   
   
       7 . The mold according to  claim 1 , wherein the deformable material has a variable upper surface contacting the bottom of the packaging substrate during mold clamping.  
   
   
       8 . A mold for use in packaging integrated circuits comprising: 
 a hardened steel lower mold portion;    a hardened steel upper mold portion having a cavity for receiving an integrated circuit die therein, wherein the upper and lower mold portions are adapted to contact opposing surfaces of a packaging substrate on which the integrated circuit die is mounted during mold clamping; and    a deformable material on at least a portion of a surface of the lower mold portion contacting the bottom surface of the packaging substrate during mold clamping.    
   
   
       9 . The mold according to  claim 8 , wherein the deformable material deforms during mold clamping to accommodate thickness variations in the packaging substrate.  
   
   
       10 . The mold according to  claim 8 , wherein the deformable material deforms during mold clamping to accommodate non-planarity of an adhesive between the integrated circuit die and the packaging substrate.  
   
   
       11 . The mold according to  claim 8 , wherein the upper mold portion includes a cavity receiving the integrated circuit die, the upper mold portion contacting the upper surface of the packaging substrate around a periphery of the cavity during mold clamping.  
   
   
       12 . The mold according to  claim 11 , wherein the upper mold portion includes a projection having a surface contacting an active area of the integrated circuit die during mold clamping.  
   
   
       13 . The mold according to  claim 12 , wherein the deformable material deforms during mold clamping to accommodate thickness variations in the packaging substrate, non-planarity of an adhesive between the integrated circuit die and the packaging substrate, or both.  
   
   
       14 . The mold according to  claim 8 , wherein the deformable material has a variable upper surface contacting the bottom of the packaging substrate during mold clamping.  
   
   
       15 . A method of packaging integrated circuits comprising: 
 clamping an upper mold portion and a lower mold portion around an integrated circuit die mounted on an upper surface of a packaging substrate, the upper and lower mold portions contacting upper and lower surfaces of the packaging substrate, respectively, during clamping,    wherein a deformable material on a surface of the lower mold portion contacts the bottom surface of the packaging substrate during mold clamping.    
   
   
       16 . The method according to  claim 15 , wherein the deformable material deforms during mold clamping to accommodate thickness variations in the packaging substrate.  
   
   
       17 . The method according to  claim 15 , wherein the deformable material deforms during mold clamping to accommodate non-planarity of an adhesive between the integrated circuit die and the packaging substrate.  
   
   
       18 . The method according to  claim 15 , further comprising: 
 receiving the integrated circuit die within a cavity in the upper mold portion during clamping, wherein the upper mold portion contacts the upper surface of the packaging substrate around a periphery of the cavity during mold clamping.    
   
   
       19 . The method according to  claim 18 , further comprising: 
 bringing a surface on a projection within the upper mold portion into contact with an active area of the integrated circuit die during mold clamping.    
   
   
       20 . The method according to  claim 19 , wherein the deformable material deforms during mold clamping to accommodate thickness variations in the packaging substrate, non-planarity of an adhesive between the integrated circuit die and the packaging substrate, or both.