Thermal conductive sheet with conductive foil

Abstract

A thermal conductive sheet with conductive foil is obtained by press bonding a magnetic foil to a thermal conductive layer via a primer layer. Since the primer layer contains a thermal conductive filler, it has high thermal conductivity and does not interrupt thermal conduction from the thermal conductive layer to the magnetic foil. It also spontaneously destroys a skin layer on the surface of the thermal conductive layer upon the press bonding. Accordingly, the thermal conductive sheet with conductive foil of the present invention improves thermal conduction from the thermal conductive layer to the conductive foil, eliminating the unfavorable effects of the skin layer and the primer layer, and thus improves heat radiation of the thermal conductive sheet with conductive foil.

What is claimed is:  
     
         1 . A thermal conductive sheet comprising a thermal conductive layer press bonded to a conductive foil via a primer layer into which a thermal conductive filler in the form of powder, chop, whisker or fiber is mixed.  
     
     
         2 . The thermal conductive sheet as set forth in  claim 1 , wherein said conductive foil is magnetic foil.  
     
     
         3 . A thermal conductive sheet for use as a thermal conductive layer between a heat producing element and a heat dissipating element, the thermal conductive sheet comprising: 
 a conductive foil;    a thermal conductive layer; and    a primer layer situated between the conductive foil and the thermal conductive layer to facilitate the adherence and thermal conductivity between the conductive foil and the thermal conductive layer.    
     
     
         4 . The thermal conductive sheet as set forth in  claim 3  wherein the primer layer comprises a thermal conductive filler material in the form of powder, chop, whisker or fiber.  
     
     
         5 . The thermal conductive sheet as set forth in  claim 4  wherein the conductive foil is press bonded to the thermal conductive layer via the primer layer.  
     
     
         6 . The thermal conductive sheet as set forth in  claim 4  wherein the thermal conductive layer has a first surface having a skin layer which is mechanically destroyed during press bonding to enhance thermal conductivity through the skin layer.  
     
     
         7 . The thermal conductive sheet as set forth in  claim 3  wherein the conductive foil is a magnetic metallic foil.  
     
     
         8 . The thermal conductive sheet as set forth in  claim 7  wherein the magnetic metallic foil is a flat rolled magnetic material chosen from the group of Fe—Si, Fe—Cr, Fe—Si—Al, Fe, Fe—Ni, Fe-based nanocrystal.  
     
     
         9 . The thermal conductive sheet as set forth in  claim 4  wherein the primer layer is fabricated from a thermoplastic base material of paraffin or polyethylene rubber or resin and the thermal conductive filler Ls chosen from the group, alumina, silicon carbide, boron nitride, metal oxide, metallic powder.  
     
     
         10 . A process of forming a thermal conductive sheet for use as a thermal conductive layer between a heat producing element and a heat dissipating element, the method of forming the thermal conductive sheet comprising the steps of: 
 forming a primer layer having a base material containing a thermal conductive filler material in the form of powder, chop, whisker or fiber and    sandwiching the primer layer between a conductive foil and a thermal conductive layer to facilitate the adherence and thermal conductivity between the conductive foil and the thermal conductive layer.