A laminate comprising an insulation layer sandwiched between a pair of electrically conductive layers is prepared for electrical insulation testing by using a laser to remove a strip from at least one of the conductive layers proximate the edge of the laminate to electrically isolate a central, bulk portion of the conductive layer from the edges of the laminate. Conductive material that may be smeared across an edge of the laminate will not therefore provide an electrical short between the portion of the conductive layer surrounded by the slot and the second conductive layer on the opposite side of the insulation layer.