An electronic device is attached to a first surface of a board which includes vias. A heat sink precursor for the electronic device is attached to the second surface of the electronic board. The heat sink precursor includes a cavity facing the vias. A wave of solder is applied to the second surface. The solder penetrates into the cavity of the heat sink precursor and flows by capillary action through the vias to join a thermal radiator and/or electronic contact of the electronic device to the vias. The solder further remains in the cavity to form a corresponding heat sink.