An integrated circuit package with a path of high thermal conductivity is disclosed. A thermally conductive slug, formed of a material such as copper, is attached to an underside portion of a substrate, such as a printed circuit board or a ceramic substrate, through which an opening has been formed....http://www.google.se/patents/US5991156?utm_source=gb-gplus-sharePatent US5991156 - Ball grid array integrated circuit package with high thermal conductivity
