Microelectronic or optoelectronic package having a polybenzoxazine-based film as an underfill material

Abstract

Microelectronic and optoelectronic packaging embodiments are described with underfill materials including polybenzoxazine, having the general formula:

1 . A method of constructing an electronic assembly, comprising: 
 adhering an electronic die to a substrate with a film including polybenzoxazine.    
   
   
       2 . The method of  claim 1 , wherein the film includes a plurality of electrically conductive members, each member electrically connecting a respective contact on the die with a respective pad on the substrate.  
   
   
       3 . The method of  claim 1 , wherein the film is formed by reacting a cationic polymerization initiator with 2H-1,3,-dihydrobenzoxazine monomers at a temperature from about −100° C. to about 250 C.  
   
   
       4 . The method of  claim 3 , wherein the cationic polymerization initiator comprises PCl 5 , PCl 3 , POCl 3 , TiCl 5 , (C 6 H 5 ) 3 C + (SbCl 6 ) − , SbCl 5 , methyl triflate, methyl tosylate, triflic acid, or aluminum phthalocyanine chloride or combinations thereof.  
   
   
       5 . The method of  claim 3 , wherein the 2H-1,3,-dihydrobenzoxazine monomers forming the polymer comprise at least 25 mole percent of one or more monomers of the formula  
     
       
         
         
             
             
         
       
     
     wherein R 1  individually is hydrogen, one or more groups selected from alkyls of 1 to 10 carbon atoms, an aromatic, alkyl substituted aromatics, or aromatic substituted alkyls of 6 to 20 carbon atoms, aromatic ring and 6 to 20 carbon atoms mono or poly fluorine substituted alkyls of 1 to 20 carbon atoms, mono or poly fluorine substituted compound having at least one or a benzoxazine from a phenolic compound of 6 to 20, n is from 1 to 4; 
 wherein each R 2  is an alkyl of 1 to 10 carbon atoms, an aromatic, alkyl substituted aromatic, or aromatic substituted alkyl of 6 to 20 carbon atoms, or an amine of 1 to 10 carbon atoms, or a benzoxazine of 9 to 20 carbon atoms; and  
 wherein R 3  is H or R 2  and p is an integer from 0 to 3.  
 
   
   
       6 . The method of  claim 3 , wherein at least 20 mole % of the repeat units of the polymer arc of structure I.  
   
   
       7 . A method of constructing an electronic assembly, comprising: 
 locating a film between a substrate and an electronic die; and    curing the film by first heating the film and then allowing the film to cool, the film having less than 0.2% shrinkage during curing.    
   
   
       8 . The method of  claim 7 , wherein the film expands by at least 0% during curing.  
   
   
       9 . The method of  claim 7 , wherein the film has a modulus of at least 1 GPa, a strength of at least 80 MPa, and an impact strength of at least 15 J/m.  
   
   
       10 . The method of  claim 9 , wherein the film has a modulus of at least 4 GPa, a strength of at least 130 MPa, and an impact strength of at least 30 J/m.  
   
   
       11 . The method of  claim 7 , wherein the film, without any filler material, has a CTE of less than 70 ppm/° C.  
   
   
       12 . The method of  claim 7 , wherein the film includes a polybenzoxazine polymer.