Electro-mechanical analysis of thin-film substrate fuses using finite element methodology.

In this thesis the electro-thermo-mechanical behaviour and withstand performance of constricted high-breaking capacity thin/thick film substrate fuse elements is examined. Three-dimensional time-varying non-linear CAD finite element modelling and simulation techniques were used to investigate the current-carrying capacity of a variety of single-layer and multilayer fuse geometries for DC and repetitive currents. The critical electro-thermally-induced stresses and strains were identified, and the techniques to achieve a reduction in the magnitude of these stresses & strains were investigated. Computational tools were developed to enable the prediction of the lifetime of thick-film substrate fuses subjected to cyclic-current loading conditions. The lifetime of a manufactured substrate fuse, subjected to a range of pulsed currents, was determined theoretically and correlated with the experimental findings. The onset of crack formation, conductive film de-bonding and lifting from the substrate and fatigue were studied computationally and experimentally. Photographic evidence of crack formation and propagation in the conductive film, film de-bonding from the substrate, metal dislocation and deformation in thin-thick film substrate fuse elements subjected to current pulses is presented.