Morphing fillers and thermal interface materials

Abstract

A thermally conductive mechanically compliant pad including a quantity of gallium and/or indium alloy liquid at temperatures below about 120° C. and a boron nitride particulate solid blended into the liquid metal alloy to form a paste. The paste is then combined with a quantity of a matrix forming flowable plastic resin such as microwax, silicone wax, or other silicone polymer to form the thermally conductive mechanically compliant pad, the compliant pad comprising from between about 10% and 90% of metal alloy coated particulate, balance flowable plastic resin.

1. A method of preparing thermally conductive mechanically compliant pads comprising the steps of:
 (a) selecting a quantity of an indium containing alloy which has a melt temperature of between about 40° C. and 120° C.  
 (b) treating said alloy to cause dispersal into divided form;  
 (c) combining said dispersed alloy with a compatible surface active agent and thermally conductive particles and blended to form a paste; and  
 (d) combining said dispersed alloy containing paste with a quantity of a flowable plastic resin material to form a thermally conductive mechanically compliant pad with said thermally conductive mechanically compliant pad comprising from between about 10% and 90% by volume of the combined dispersed metal alloy and thermally conductive particulate, balance flowable plastic resin.  
 
     
     
       2. The method of  claim 1  wherein the particles making up said thermally conductive particulate solid have a diameter of between about 1 and 40 microns. 
     
     
       3. The method of  claim 1  wherein said liquid alloy substantially encapsulates said thermally conductive particles to form a coating thereon, and wherein the liquid metal to thermally conductive particle volume ratio is at least 3:1. 
     
     
       4. The method of  claim 1  wherein said blended paste is further blended with microwax or silicone wax to form a conformable pad, with the pad comprising between about 10% and 90% by volume of homogeneous paste, balance microwax or silicone wax. 
     
     
       5. The method of  claim 1  being particularly characterized in that said liquid metal alloy is in liquid state at temperatures above 60° C. 
     
     
       6. The compliant thermally conductive pad prepared in accordance with the steps of  claim 1 . 
     
     
       7. A method of preparing thermally conductive mechanically compliant pads comprising the steps of:
 ( a )  selecting a quantity of an indium containing alloy which has a melt temperature of between about  40 ° C. and  120 ° C.;      ( b )  treating said alloy to cause dispersal into divided form;      ( c )  combining said dispersed alloy with thermally conductive particles and blending the combination to form a paste; and      ( d )  combining said dispersed alloy containing paste with a quantity of a flowable plastic resin material to form a thermally conductive mechanically compliant pad with said thermally conductive mechanically compliant pad comprising between about  10   %  and  90   %  by volume of the combined dispersed metal alloy and thermally conductive particulate, balance flowable plastic resin.     
     
     
       8. A thermally conductive electrically- resistive mechanically compliant pad comprising a mixture of:    ( a )  between about  10   %  and  90   %  by volume of a paste, which paste includes a blend of:  
 ( i )  an indium containing alloy having a melt temperature of between about  40 ° C. and  120 ° C.;    
 ( ii )  thermally conductive particles, at least a portion thereof being dispersed within at least a portion of said indium containing alloy; and    
   ( b )  balance flowable plastic resin.     
     
     
       9. A thermally conductive electrically- resistive mechanically compliant pad comprising:    ( a )  an indium containing alloy having a melt temperature of between about  40 ° C. and  120 ° C., and being in divided particulate form of between about  1  and  100  μm in diameter; and      ( b )  a polymeric resin material having a melt temperature of between about  40 ° C. and  120 ° C.     
     
     
       10. A thermally conductive mechanically compliant pad as in  claim 9 , including a compatible surface active agent. 
     
     
       11. A thermally conductive mechanically compliant pad as in  claim 9  wherein the melt temperature of said polymeric resin material is about  10 ° C. lower than the melt temperature of said indium containing alloy.