DYNAMIC FRACTURE TEST OF METAL THIN-FILMS DEPOSITED ON AN INSULATING SUBSTRATE BY A HIGH-CURRENT PULSE METHOD

In this paper we describe a novel technique for determining the dynamic fracture strength of metal thin films deposited on an insulating substrate by flowing through the films a high current pulse of short duration. Examples are provided with the films of high conductivity materials such as aluminum, copper, gold and silver, which were all deposited on a fused quartz disk. The high current flow heats the film, which is then loaded with thermal stresses caused by a mismatch of thermal expansions of the film and substrate materials. On heating, the thin film is subjected to a state of triaxial compression. Among the film materials tested, copper shows the toughest fracture strength and gold the weakest. The fracture strengths of silver and aluminum films lie between those of the gold and copper films.