Moisture resistant, flexible epoxy/cyanate ester formulation

Abstract

Compositions having high moisture resistance and flexibility comprise an organic component and a filler. The organic component comprises a long-chain cycloaliphatic epoxy resin, a short-chain cycloaliphatic epoxy resin, a cyanate ester, and a lewis acid catalyst. Preferably the organic component further comprises a bronsted acid co-catalyst and/or a flexibilizing modifier. The compositions are useful in various semiconductor applications, including as die attach adhesives, underfills, encapsulants, via fills, prepreg binders, polymer solder masks and polymer bumps on flip chip or BGA assemblies.

1 - 93 . (canceled)  
     
     
         94 . A composition comprising an organic component and a filler, wherein the organic component comprises: 
 at least one long-chain cycloaliphatic epoxy resin,    at least one short-chain cycloaliphatic epoxy resin,    at least one cyanate ester,    at least one Lewis acid catalyst, and    at least one flexibilizing modifier.    
     
     
         95 . The composition of  claim 95 , wherein the composition further comprises at least one Bronsted acid co-catalyst.  
     
     
         96 . The composition of  claim 96 , wherein the at least one Bronsted acid co-catalyst is a weak Bronsted acid catalyst.  
     
     
         97 . The composition of  claim 95 , wherein the at least one Bronsted acid co-catalyst comprises phenol-based molecules, diketonates, diesters or ketoesters.  
     
     
         98 . The composition of  claim 95 , wherein the at least one Bronsted acid co-catalyst is present in an amount ranging from about 0.3% to about 0.8% by weight based on the total weight of the organic component.  
     
     
         99 . The composition of  claim 94 , wherein the at least one flexibilizing modifier comprises at least one functionalized flexible long-chain compounds.  
     
     
         100 . The composition of  claim 99 , wherein the at least one functionalized compound comprises epoxy-terminated siloxanes, epoxy/hydroxy functionalized polybutadiene, epoxidized oils, long-chain functionalized double bond compounds or a combination thereof.  
     
     
         101 . The composition of  claim 100 , wherein the epoxidized oils comprise epoxidized methyl linseedate.  
     
     
         102 . The composition of  claim 100 , wherein the long-chain funcationalized double bond compounds comprise acrylates, rubbers or a combination thereof.  
     
     
         103 . The composition of  claim 102 , wherein the acrylates comprise urethane acrylates or methacrylated polybutadiene acrylonitrile.  
     
     
         104 . The adhesive of  claim 94 , wherein said at least one long-chain cycloaliphatic epoxy resin is selected from the group consisting of cycloaliphatic mono- and di-epoxy oligosiloxanes.  
     
     
         105 . The adhesive of  claim 94 , wherein said at least one long-chain cycloaliphatic epoxy resin is selected from the group consisting of bis[3,4-epoxy-cyclo-hexyl-methyl]adipate, epoxidized α,ω-di-(3,4 cyclohexene-2-ethyl)-tetramethyl disiloxane, epoxidized α,ω-di-(3,4-cyclohexene-2-ethyl-hexamethyl trisiloxane, and epoxidized α-3,4-cyclohexene-2-ethyl pentamethyldisiloxane.  
     
     
         106 . The adhesive of  claim 94 , wherein said at least one long-chain cycloaliphatic epoxy resin is present the composition in an amount ranging from about 5% to about 20% by weight based on the total weight of the organic component.  
     
     
         107 . The adhesive of  claim 94 , wherein said at least one long-chain cycloaliphatic epoxy resin is present the composition in an amount ranging from about 12% to about 15% by weight based on the total weight of the organic component.  
     
     
         108 . The adhesive of  claim 94 , wherein said at least one short-chain cycloaliphatic epoxy resin has a short chain between the cycloaliphatic groups containing 2 or less carbon atoms.  
     
     
         109 . The adhesive of  claim 94 , wherein said at least one short-chain cycloaliphatic epoxy resin is selected from the group consisting of 3,4-epoxy-cyclohexylmethyl-3,4-carboxylate, vinyl cyclohexene dioxide, and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane meta-dioxane.  
     
     
         110 . The adhesive of  claim 94 , wherein said at least one cyanate ester has two or more isocyanate functional groups.  
     
     
         111 . The adhesive of  claim 94 , wherein said at least one cyanate ester comprises 1,1′-bis[4-cyanatophenyl]ethane, bis(4-cyanato-3,5-dimethylphenyl)methane, and 1,3-bis(cyanatophenyl-1-(1-methylethylethylidene))benzene.  
     
     
         112 . The adhesive of  claim 94 , wherein the Lewis acid catalyst comprises a compound selected from the group consisting of titanium-based compounds, organo-tin compounds, zirconium-based compounds, tantalum-based compounds, vanadium-based compounds, boron-amine complexes, boron complexes, boron halides, amino complexes of boron halides, and aluminum halides.