Method of using pre-applied underfill encapsulant

Abstract

The invention relates to a method for utilizing one or more encapsulant compositions containing an expandable or pre-expanded filler on an electronic component.

1 . A method of preparing one or more electronic components, comprising the steps of 
 a) applying encapsulant containing at least one expandable filler material to at least a portion of one or more electronic components;    b) B-stage processing the encapsulant on the one or more electronic components so that the encapsulant solidifies into a smooth, non-tacky coating; and    subjecting the one or more components to heat such that the expandable filler expands to form a closed-cell structure within the encapsulant.    
     
     
         2 . The method of  claim 1 , wherein the encapsulant is applied to the component via spin coating, screen-printing or stencil printing. Or as a patterned free standing film (a film with preformed holes)  
     
     
         3 . The method of  claim 1 , wherein the encapsulant is applied in the form of a patterned free-standing film.  
     
     
         4 . The method of  claim 1 , wherein the one or more expandable filler is selected from the group comprising microspheres, expandable balloons, and mixtures thereof.  
     
     
         5 . The method of  claim 1 , wherein the one or more expandable fillers comprises in the range of about 0.1 wt % to about 10 wt % of the encapsulant.  
     
     
         6 . The method of  claim 1 , wherein the one or more expandable fillers expand upon exposure to temperatures greater than about 150 C.  
     
     
         7 . The method of  claim 1 , wherein the encapsulant is provided in the form of a film.  
     
     
         8 . The method of  claim 1 , wherein the at least one component comprises a CSP.  
     
     
         9 . The method of  claim 1 , wherein the at least one component comprises a PCB.  
     
     
         10 . The method of  claim 1 , further comprising the step of providing an expanded filler material.  
     
     
         10 . A method of preparing one or more electronic components comprising the steps of: 
 a) applying an encapsulant containing at least one expandable filler material to at least a portion of the one or more components; and    b) subjecting the one or more components to heat such that the expandable filler expands to form a closed-cell structure within the encapsulant.    
     
     
         11 . A method of preparing one or more electronic components comprising the step of: 
 applying an encapsulant containing at least one pre-expanded filler material to at least a portion of the one or more components.    
     
     
         12 . The method of  claim 10 , wherein the at least one pre-expanded filler material comprises hollow particles.  
     
     
         13 . The method of  claim 10 , wherein the at least one pre-expanded filler material is formed by one or more blowing agents.  
     
     
         14 . A method of preparing an electronic component for application to a substrate, comprising the step of providing a non-tacky, free-standing underfill film on one or more electronic components.  
     
     
         15 . The method of  claim 14 , wherein the film is B-staged on the one or more electronic components to form a smooth, non tacky coating.  
     
     
         16 . The method of  claim 14 , wherein the film is applied as a patterned free standing film.  
     
     
         17 . The method of  claim 14 , wherein the film is applied to an electronic component that has one or more solder ball interconnects and the film has a thickness that is less than the height of the one or more solder ball interconnects.  
     
     
         18 . The method of  claim 14 , wherein the storage modulus of the film is less than 1000 MPa.  
     
     
         19 . The method of  claim 18 , wherein the storage modulus of the film is less than 100 MPa  
     
     
         20 . The method of  claim 19 , wherein the storage modulus of the film is less than 10 MPa.