Abstract
The various equations used by different authors for describing electromigration are compiled. All of them can be derived from a general equation which is based on a vacancy model. During the derivation of simplified versions of the general equations assumptions have to be made and their effect on concentration profiles and/or electromigration stresses developing as a function of time are discussed. Consequences with respect to Blech's experiment or the current exponent in Black's equation are taken into consideration and a simple explanation is provided for the beneficial effect of a (111) texture on the reliability of Al-lines.