This user document provides guidance regarding how the IPC-TM-650, Method 2.6.25, Conductive Anodic Filament (CAF) Resistance Test can best be used for evaluating the effects of mechanical stress, laminate material fracturing, ionic contamination, moisture content prior to press lamination, and other material processing characteristics on conductive anodic filament (CAF) test method results. This CAF test method provides a proven standard for determining the risk of temperature, humidity and bias (THB) failure within rather than on the surface of printed circuit boards (PCBs), typically filament formation along the boundary between the resin and laminate reinforcement.