Methods for forming leadframe-based semiconductor packages having curvilinear shapes are disclosed. The leadframes may each include one or more curvilinear slots corresponding to curvilinear edges in the finished and singulated semiconductor package. After encapsulation, the integrated circuit packages on the panel may be singulated by cutting the integrated circuits from the leadframe panel into a plurality of individual integrated circuit packages. The slots in the leadframe advantageously allow each leadframe to be singulated using a saw blade making only straight cuts.