Abstract: An apparatus for cooling an array of integrated circuit chips mounted on a substrate comprises a thermally conductive cooling plate which has a plurality of integral, substantially parallel, closed-end channels. A cover which may be made of plastic is adapted to seal the periphery of the cooling member and is spaced from the channel-containing surface. The cover has a plurality of integral baffles extending toward the cooling member into and along the length of the channels. The baffles and the channels are spaced from each other to permit passage of a coolant between and through the channels in a flow direction normal to the channels. An inlet and outlet for the coolant are provided on opposite ends of the apparatus, and may be located in the cover. In an alternate embodiment, the cooling plate contains at least two sets of the channels, each set of channels receiving a separate flow of coolant, either in parallel or in series with each other.