A functional element comprising a shaft part and a head part, or a hollow body part, for attachment to a sheet
metal part, in particular for liquid-tight and / or gas-tight attachment to the sheet
metal part, without penetrating or perforating the sheet
metal part, is characterized in that the head or body part has at least one
undercut feature either in an open hollow cavity at its end face confronting the sheet metal part and / or at its outer periphery and is formed in the regions which enter into contact with the sheet metal part with exclusively rounded shaping edges which, during the
insertion of the element, cooperate with a shaping die button in order to provide a hooked engagement in form-fitted manner of the sheet metal material, with the
undercut feature or with the
undercut features. A method of attaching a functional element to a sheet metal part, a component
assembly and also at least one die button and a setting head are disclosed and claimed.