At least one power semiconductor component is cooled by a flat, copper, plate-type hollow body conducting a coolant fluid. Components are fixed on one flat-sided surface of the hollow body and the other flat-sided surface includes two coolant fluid openings for introducing the coolant fluid into the hollow body and for evacuating the fluid therefrom. The other flat-sided surface is concave and elastically deformable between the coolant fluid openings. The concave other surface is attached to the even surface of a support in such a way that the concave surface and the even surface are pressed against each other by the elastically planar deformation of the concave surface and that the coolant fluid openings are sealed in a fluidproof manner by O-rings. A solid strut, which interconnects the two flat-sided surfaces is additionally configured in the hollow body. The cooling device may be used in a module or an assembly including a support and the cooling device or module. The device is useful in electric transmissions, in particular, in motor vehicles.