In this paper, the atomic flux divergence (AFD) based flow for AC and pulsed DC signal line electromigration (EM) reliability estimation is proposed. The flow is implemented as a 3-stage filter based on the average (AVG) and root-mean-square (RMS) current densities. A relationship between AVG and/or RMS current densities, maximum AFD, and EM lifetime is established and validated. To avoid the necessity of solving finite element equations, SPICE-based simulation scheme is proposed for fast AFD calculation. Fitting functions to evaluate signal line EM with AC and pulsed DC patterns are proposed. To prove fidelity, healing factors for AC EM obtained from our method are verified against measured results. Results of the traditional and proposed methods are compared.