The apparatus includes a housing, a heat sink arranged in the housing, semiconductor switching elements mounted on the heat sink and having terminals, a circuit board arranged in opposition to the heat sink and having an electronic circuit formed thereon including a control circuit for controlling the semiconductor switching elements, and a plurality of conductive plates electrically connecting the circuit board and the semiconductor switching elements to each other. The individual conductive plates are arranged along a lead-out direction in which the individual terminals of the semiconductor switching elements lead out, so that they are bonded to the individual terminals.