The invention relates to a device for ultrasonic welding of at least two plastic foil layers for manufacturing for example a package. The device comprises at least one sonotrode and at least one anvil positioned opposite each other and each being provided with a pressure surface. The pressure surfaces can be moved away from each other and towards each other from a position of rest to a welding position and vice versa, the pressure surfaces in the welding position forming a welding section as well as a flow-out section. The pressure surfaces in the flow-out section have at least two pressure surface areas extending substantially parallel to each other for supporting the foil layers.