A method of manufacturing an organic light emitting display panel is disclosed. The method may include forming a thin film layer using an open mask. The open mask may include forming a half-etching portion disposed over at least a portion of a non-display area. The non-display area may include a portion in which a first line crosses a second line. In a final product, a distance between a substrate and a lower surface of the half-etching portion may be longer than the distance between the substrate and a lower surface of a non-opening portion. Because of the half-etching portion, lines disposed in the non-display area may be prevented from contacting the open mask.