Thermal Interface Materials

Abstract

The present invention relates to thermal interface materials comprising a filler dispersed in a polymer, wherein the filler has an average aggregate particle size of less than or equal to 1 micron. Preferably the filler is a synthetic alumina, such as fumed alumina.

What is claimed is: 
     
         1 - 25 . (canceled) 
     
     
         26 . A thermal interface material comprising:
 at least 27.65% by weight of either an epoxy polymer, a polysiloxane polymer, or both; and   a modified fumed alumina dispersed in the polymer, the modified fumed alumina having attached at least one organic group, the modified fumed alumina having an average aggregate particle size of less than or equal to 1 micron and a surface area of greater than or equal to about 30 m 2 /g.   
     
     
         27 . The thermal interface material of  claim 26  comprising greater than or equal to 10% by weight of the modified fumed alumina and wherein the viscosity of the thermal interface material consistently decreases with an increasing shear rate from 0.01/s to 100/s. 
     
     
         28 . The thermal interface material of  claim 26  wherein the at least one organic group is a silane group. 
     
     
         29 . The thermal interface material of  claim 26  wherein the at least one organic group comprises an alkyl group. 
     
     
         30 . The thermal interface material of  claim 26 , wherein the modified fumed alumina has a surface area of greater than or equal to about 40 m 2 /g. 
     
     
         31 . The thermal interface material of  claim 26 , wherein the modified fumed alumina has a surface area of greater than or equal to about 50 m 2 /g. 
     
     
         32 . The thermal interface material of  claim 26 , wherein the modified fumed alumina has a surface area of less than or equal to about 100 m 2 /g. 
     
     
         33 . The thermal interface material of  claim 26  wherein the polymer is a polysiloxane resin. 
     
     
         34 . The thermal interface material of  claim 26  wherein the polymer is an epoxy resin. 
     
     
         35 . The thermal interface material of  claim 26 , wherein the filler is dispersed in the polymer in an amount of between about 5% and about 80% by weight based on the total weight of the material. 
     
     
         36 . The thermal interface material of  claim 26 , wherein the filler is dispersed in the polymer in an amount of between about 30% and about 60% by weight based on the total weight of the material. 
     
     
         37 . The thermal interface material of  claim 26  further comprising at least one additional particulate material having an average aggregate particle size of greater than 1 micron. 
     
     
         38 . The thermal interface material of  claim 37 , wherein the additional particulate material is fused silica, finely divided quartz powder, amorphous silica, graphite, diamond, silicon carbide, aluminum hydrates, aluminum oxides, zinc oxides, aluminum nitrides, boron nitrides, coarse alumina, or combinations thereof. 
     
     
         39 . The thermal interface material of  claim 37 , wherein the additional particulate material and the modified fumed alumina are dispersed in the polymer in a total amount of between about 25% and about 90% by weight based on the total weight of the dispersed material. 
     
     
         40 . The thermal interface material of  claim 37 , wherein the second particulate material and the modified fumed alumina are dispersed in the polymer in a total amount of between about 30% and about 85% by weight based on the total weight of the material. 
     
     
         41 . An electronic component system comprising:
 a heat generating component;   a heat dissipating component; and   a thermal interface material disposed between the heat generating component and the heat dissipating component, the thermal interface material comprising:
 a modified fumed alumina having an average aggregate particle size of less than or equal to 1 micron and a surface area of greater than or equal to about 30 m 2 /g; and 
 a polymer selected from epoxy resins, polysiloxane resins or a combination thereof. 
   
     
     
         42 . The electronic component system of  claim 41  wherein the modified fumed alumina comprises a fumed alumina having an organic group attached thereto wherein the organic group is attached to the fumed alumina by a chemical reaction. 
     
     
         43 . A method comprising:
 dispersing greater than 10% by weight of a modified fumed alumina in a resin system to produce a dispersion, the modified fumed alumina having an aggregate particle size of less than one micron, and the resin system comprising at least one of an epoxy resin and a polysiloxane resin;   disposing the dispersion between a heat generating component and a heat dissipating component; and   crosslinking the resin system.   
     
     
         44 . The method of  claim 43  further comprising dispersing a second alumina in the resin system, the second alumina having an average aggregate particle size of greater than 1 micron. 
     
     
         45 . The method of  claim 43  comprising dispersing greater than 20% by weight of the modified fumed alumina in the resin system.