US Patent 7859848 Heat spreader and method of making the same

A heat spreader having at least two adjoining strips of pyrolytic graphite material is made by cutting a strip from a sheet of pyrolytic graphite in the z direction. Thermal conductivity in the xy plane of the graphite sheet is greater than in the z direction. The z direction cut provides strips which are then each individually oriented 90 degrees such that the thickness direction of the original pyrolytic graphite sheet becomes the width or length of the cut strip. A face on the side of a first strip adjoins a face on the side of a second strip. Due to the greater thermal conductivity in the xy plane of the strips as compared to in the z direction heat transfers more rapidly in the length and thickness direction of the strips than across adjoining sides of the oriented strips.