Thermally-conductive electrically-insulating polymer-base material

Abstract

An electrically-insulating polymer-based material with improved thermal conductivity so as to be suitable for use as an adhesive for mounting and conducting heat from electronic devices. The polymer-based material comprises metal particles dispersed in a matrix material. The metal particles are encapsulated by a dielectric coating so that they are electrically insulated from each other. The polymer-based material may also comprise dielectric particles dispersed in the matrix material and/or the dielectric coating for the purpose of further increasing the thermal conductivity of the polymer-based material. The material is also suitable for use as a potting compound or an encapsulation material for various electronic applications.

1 . A polymer-based material comprising: 
 a polymer matrix material; and    metal particles dispersed in the matrix material; and    a dielectric coating encapsulating each of the metal particles so as to electrically insulate the metal particles from each other, the dielectric coating being insoluble in the matrix material and having a softening temperature below the melting temperature of the metal particles.    
     
     
         2 . The polymer-based material according to  claim 1 , wherein the matrix material is formed of an epoxy, silicone, or polyurethane.  
     
     
         3 . The polymer-based material according to  claim 1 , wherein the metal particles are formed of copper, aluminum or silver.  
     
     
         4 . The polymer-based material according to  claim 1 , further comprising dielectric particles dispersed in the matrix material, the dielectric particles having a higher coefficient of thermal conductivity than the matrix material.  
     
     
         5 . The polymer-based material according to  claim 4 , wherein the dielectric particles are formed of a ceramic material.  
     
     
         6 . The polymer-based material according to  claim 4 , wherein the dielectric coating comprises second dielectric particles dispersed therein, the second dielectric particles being smaller than the dielectric particles dispersed in the matrix material.  
     
     
         7 . The polymer-based material according to  claim 6 , wherein the second dielectric particles are formed of a ceramic material having a higher coefficient of thermal conductivity than the matrix material.  
     
     
         8 . The polymer-based material according to  claim 1 , wherein the dielectric coating is a polymer having a softening temperature of at least 175° C.  
     
     
         9 . The polymer-based material according to  claim 1 , wherein the dielectric coating comprises dielectric particles dispersed therein.  
     
     
         10 . The polymer-based material according to  claim 1 , wherein the polymer-based material is an adhesive that bonds a heat-generating power device to a substrate.  
     
     
         11 . The polymer-based material according to  claim 1 , wherein the polymer-based material is an adhesive that bonds a heat-generating power device to a substrate.  
     
     
         12 . The polymer-based material according to  claim 1 , wherein the polymer-based material encases a heat generating power device.  
     
     
         13 . An adhesive material contacting a heat-generating electronic device, the adhesive material comprising: 
 about 50 to about 80 weight percent of metal particles having a melting temperature about a maximum operating temperature of the heat-generating electronic device;    a dielectric polymer coating individually encapsulating each of the metal particles so as to electrically insulate the metal particles from each other, the polymer coating having a softening temperature of at least the maximum operating temperature of the heat-generating electronic device but below the melting temperature of the metal particles;    about 0.5 to about 10 weight percent of dielectric particles; and    the balance essentially a polymeric gel in which the metal particles and the dielectric particles are dispersed, the dielectric particles having a higher coefficient of thermal conductivity than the gel.    
     
     
         14 . The adhesive material according to  claim 13 , wherein the dielectric particles are formed of alumina, boron nitride, aluminum nitride, silicon carbide and/or silicon nitride.  
     
     
         15 . The adhesive material according to  claim 13 , wherein the dielectric polymer coating comprises about 50 to 90 weight percent of second dielectric particles dispersed therein, the second dielectric particles having a higher coefficient of thermal conductivity than the gel.  
     
     
         16 . The adhesive material according to  claim 15 , wherein the second dielectric particles are formed of alumina, boron nitride, aluminum nitride, silicon carbide and/or silicon nitride.  
     
     
         17 . The adhesive material according to  claim 15 , wherein the second dielectric particles are smaller than the dielectric particles dispersed in the gel.  
     
     
         18 . The adhesive material according to  claim 13 , wherein the gel is an epoxy, silicone or polyurethane.  
     
     
         19 . The adhesive material according to  claim 13 , wherein the adhesive material bonds the heat-generating electronic device to a substrate.  
     
     
         20 . The adhesive material according to  claim 13 , wherein the adhesive material encases the heat-generating electronic device.  
     
     
         21 . A polymer-based material comprising: 
 a polymer matrix material; and    metal particles dispersed in the matrix material;    a dielectric coating encapsulating each of the metal particles so as to electrically insulate the metal particles from each other, the dielectric coating being insoluble in the matrix material and having a softening temperature below the melting temperature of the metal particles; and    dielectric particles dispersed in the matrix material, the dielectric particles having a higher coefficient of thermal conductivity than the matrix material.