A semiconductor device has a composite metal heat-radiating plate consisting of, for example, two copper layers for serving as a thermally and electrically conducting medium and an iron layer for giving mechanical strength, interposed between the copper layers, in which the semiconductor element is directly...http://www.google.com.au/patents/US4057825?utm_source=gb-gplus-sharePatent US4057825 - Semiconductor device with composite metal heat-radiating plate onto which semiconductor element is soldered
