This document is the product of the IPC Electrochemical Migration (ECM) Task Group. It was drafted to provide guidance regarding implementation of the User Guide for the IPC-TM-650, Method 2.6.25, Conductive Anodic Filament (CAF) Resistance and Other Internal Electrochemical Migration Testing to evaluate the effects of mechanical stress, laminate material fracturing, ionic contamination, moisture content prior to press lamination and other material processing characteristics on formation of conductive paths within laminate material such as conductive anodic filaments (CAF), one specific type of ECM failure mode. This internal ECM test method provides a proven standard for determining the risk of through-hole bias and other internal conductor orientations that result in significant reduction of insulation resistance internally, rather than on the surface of printed boards.