| abstract |
A thermally conductive film that includes a film of polymeric matrix material having a thickness t defined between a top surface and a bottom surface. A plurality of fibers, having a greater thermal conductivity than the polymeric matrix material, is disposed in the film and extends between the top surface and the bottom surface. Each of the fibers are oriented in the film to form a fiber-to-film surface angle theta relative to the top and bottom surfaces that is greater than about 45 DEG but is less than arctan t/d, where t is the thickness of the film and d is the diameter of the fibers in the direction of the angle theta . A shear/extruder apparatus is used to form the thermally conductive film from a sheet of composite prepreg material. An upper die block and a lower die block separated by a predetermined distance form an extrusion slot therebetween. A ram blade is dimensioned to intermittently insert into the input opening of the extrusion slot so that when the prepreg is positioned in front of the input opening, the prepreg is repetitively sheared by the ram blade to form sheared pieces that are forced into the extrusion slot and merged together to form the thermally conductive film with the fibers disposed therein extending substantially between the top surface and the bottom surface of the film and oriented to have the fiber-to-film surface angle theta . |