Methods for vacuum assisted underfilling

Abstract

Methods for applying an underfill with vacuum assistance. The method includes receiving a substrate with the surface at least partially covered by a glass-like film that has a top surface of reduced roughness relative to the surface of the substrate, providing the underfill on the top surface of the glass-like film along an exterior edge of the electronic device, evacuating the space to provide a vacuum condition in the open portion of the space, and heating the underfill to cause flow of the underfill toward the exterior edge and into the open portion of the space, wherein the glass-like film reduces trapping of gas under the underfill.

What is claimed is: 
     
         1 . A method of providing an underfill on a substrate having a surface to which an electronic device is mounted by electrically conductive joints and is separated from the substrate by a space, the space having an open portion that is unoccupied by the conductive joints, the method comprising:
 receiving the substrate with the surface at least partially covered by a glass-like film that has a top surface of reduced roughness relative to the surface of the substrate;   providing the underfill on the top surface of the glass-like film along an exterior edge of the electronic device;   evacuating the space to provide a vacuum condition in the open portion of the space; after evacuating the space to provide the vacuum condition, heating the underfill to cause flow of the underfill toward the exterior edge and into the open portion of the space,   wherein the glass-like film reduces trapping of gas under the underfill.   
     
     
         2 . The method of  claim 1  wherein obtaining the substrate with the surface at least partially covered by a glass-like film further comprises:
 depositing the glass-like film on the substrate. 
 
     
     
         3 . The method of  claim 2  further comprising:
 after depositing the glass-like film on the substrate, plasma activating a surface of the glass-like film. 
 
     
     
         4 . The method of  claim 1  further comprising:
 after depositing the glass-like film on the substrate, mounting the electronic device by the electrically conductive joints on the surface of the substrate. 
 
     
     
         5 . The method of  claim 1  providing the underfill on the top surface of the glass-like film further comprises:
 dispensing the underfill onto the top surface of the glass-like film. 
 
     
     
         6 . The method of  claim 1  wherein providing the underfill on the top surface of the glass-like film further comprises:
 placing a solid underfill onto the top surface of the glass-like film.