Electro-thermal simulation of metal interconnections under high current flow

Abstract

The present paper deals with an electro-thermal simulator able to foresee the electrical and thermal parameters of any shaped metal interconnection driven by constant current in a single-layer PCB. This proposed simulator is composed by the cyclic interaction between an electrical solver for the calculation of the current density as well as heating power density distributions and a thermal solver based on the recently proposed steady state analytical thermal simulator DJOSER [4]. In a metal interconnection, because of the temperature dependence of the resistivity, the self Joule-heating within the metal, the heating due to proximity of power devices, the packaging structure and the various thermal boundary conditions concur to change the temperature distribution and the local conductivity values within the interconnection, so that the usual hypothesis of isothermal substrate is largely unrealistic. The simulations were performed on a virtual single-layer PCB in FR-4 epoxy glass cloth with a 80 μm thick copper-foil interconnection driven with constant current. The results, showed in terms of distribution maps of current density, voltage potential, heating power density and temperature, were compared with those obtained under isothermal conditions for many values of the input current and under different average convective heat-transfer coefficients.