a rigid copper substrate 1 generally in the shape of a parallelepiped comprising a cavity 2 that is generally central enclosing a chip 3 that is attached to the bottom 4 of the cavity 2 by means of a thermally conductive adhesive 5 the substrate 1 also supports a dielectric substrate 6 that is generally flexible disposed on the periphery of the cavity 2 and hence of the chip 3 the substrate 6 supports on one of its surfaces conductive traces 7 i disposed according to a given design which include the connection areas for the bonding wires and the balls on its other surface it supports a conductive plane 8 that is attached to the substrate 1 for example using the same adhesive 9 that attaches the chip 3 to the bottom 4 of the cavity 2 the active surface 10 of the chip 3 opposite the bottom 4 of the cavity 2 is electrically connected to the traces 7 i by means of connections 11 i in this case connecting wires also called u201c bonding u201d wires the conductive traces 7 i extend from the cavity 2 and radially relative to the cavity 2 and respectively end in.