Three dimensional flip chip system and method

Abstract

Solder is simultaneously transferred from a mold to a plurality of 3D assembled modules to provide solder bumps on the modules. The mold includes cavities containing injected molten solder or preformed solder balls. A fixture including resilient pressure pads and vacuum lines extending through the pads applies pressure to the modules when they are positioned on the mold. Following reflow and solder transfer to the modules, the fixture is displaced with respect to the mold. The modules, being attached to the fixture by vacuum pressure through the pads, are displaced from the mold with the fixture.

1 . A system for forming solder bumps on three dimensional modules, comprising:
 a mold having a top surface and including a plurality of cavities, each of the cavities having an opening adjoining the top surface;   an injection head for injecting molten solder into the cavities, and   an assembly including a fixture, a plurality of resilient contact pads attached to the fixture, and a plurality of vacuum lines extending through the fixture and the resilient contact pads, the contact pads comprising vacuum openings communicating with the vacuum lines and positioned in opposing relation to the top surface of the mold.   
     
     
         2 . The system of  claim 1 , wherein the mold comprises a glass or silicon substrate, a polymer film on the substrate, the cavities being formed in the polymer film. 
     
     
         3 . The system of  claim 1 , further including a mechanism for raising and lowering the assembly with respect to the mold and for causing pressure to be applied by the contact pads in the direction of the mold. 
     
     
         4 . The system of  claim 1 , wherein the mold comprises a glass or silicon substrate, the cavities being formed in the substrate. 
     
     
         5 . The system of  claim 4 , wherein the mold further includes a polymer film lining the cavities. 
     
     
         6 . The system of  claim 1 , wherein the fixture comprises a rigid plate, the contact pads being attached to the rigid plate and being comprised of a deformable silicone material. 
     
     
         7 . A system comprising:
 a mold having a top surface and including a plurality of cavities, each of the cavities having an opening adjoining the top surface and containing solder;   an assembly including a fixture, a plurality of resilient contact pads attached to the fixture, and a plurality of vacuum lines extending through the fixture and the resilient contact pads, the contact pads comprising vacuum openings communicating with the vacuum lines and positioned in opposing relation to the top surface of the mold, and   a mechanism for raising and lowering the assembly with respect to the mold and for causing pressure to be applied by the contact pads in the direction of the mold.   
     
     
         8 . The system of  claim 7 , further including a plurality of electronic modules positioned on the mold, each of the modules engaging the top surface of the mold and overlying a plurality of the cavity openings, the solder having greater affinity for the modules than the mold, the mechanism for raising and lowering the assembly being configured for causing the contact pads to apply pressure to the plurality of electronic modules. 
     
     
         9 . The system of  claim 8 , wherein each of the electronic modules comprises an interposer wafer portion, the interposer wafer portions of the electronic modules engaging the top surface of the mold and overlying the plurality of cavity openings, the solder having greater affinity for the interposer wafer portions than the mold. 
     
     
         10 . The system of  claim 9 , wherein each of the electronic modules further comprises an integrated circuit chip electrically connected to the interposer wafer portion. 
     
     
         11 . The system of  claim 7 , wherein the mold comprises a glass or silicon substrate, a polymer film on the substrate, the cavities being formed in the polymer film. 
     
     
         12 . The system of  claim 7 , wherein the mold comprises a glass or silicon substrate, the cavities being formed in the substrate. 
     
     
         13 . The system of  claim 12 , wherein the mold further includes a polymer film lining the cavities. 
     
     
         14 . The system of  claim 7 , further including an injection head for injecting molten solder into the cavities. 
     
     
         15 . The system of  claim 7 , wherein the fixture comprises a rigid plate, the contact pads being attached to the rigid plate and being comprised of a deformable silicone material. 
     
     
         16 . The system of  claim 7 , wherein the contact pads are arranged in rows and columns. 
     
     
         17 . The system of  claim 1 , wherein the contact pads are comprised of a deformable silicone material.