Abstract: A coldplate for removing heat from one or more heat sources, such as power electronics devices, includes a baseplate including a first surface in thermally-conductive communication with the heat sources. The baseplate includes a second surface opposite the first surface to transfer heat into a cooling fluid in contact therewith. The second surface includes a peripheral flange surrounding a central region having a plurality of parallel ribs, which increase the surface area to improve heat transfer from the baseplate and into the fluid. A housing abuts the peripheral flange of the baseplate to define a cooling passage for circulation of the cooling fluid. A jet-array plate subdivides the cooling passage into a supply header and a main channel and defines a plurality of orifices to convey the fluid into the main channel and to direct the fluid toward predetermined zones on the baseplate.