Abstract: A critical temperature rise .DELTA.R is selected at a value for which electromigration of atoms in the metal conductive line deposited on a semiconductive substrate is predominantly a grain boundary electromigration. Selection of the critical resistance rise is made by performing a number of tests on different ones of a plurality of substantially identical bow tie conductive lines formed of alternating narrow and wide sections interconnected by tapering line sections. Temperatures for the selection of the critical resistance rise are calculated rather than measured so as to more accurately reflect the relatively high local temperature at the site of a void in the metallic conductive line. Plot of a plurality of line widths against temperature for a given current density enables selection of a minimum line width or maximum void depth that will occur in a condition of predominantly grain boundary electromigration and before a large amount of bulk electromigration occurs.