The present invention relates to a vacuum cleaner filter bag made of a thermally weldable filter material which forms the sealed internal space of the vacuum cleaner filter bag. The internal space is thereby closed at least on one side by means of a weld seam configured according to the invention, in the case of which at least two layers of the filter material are welded together. The weld seam configured according to the present invention is distinguished by a far higher tearing strength, compared with weld seams as are known from the state of the art. The invention relates in addition to a method for the production of the vacuum cleaner filter bag, to a tool for the production of the high-strength weld seam and also to an ultrasonic welding unit in which this tool is integrated.