A heat exchanger has a thermally conductive first plate with a flat first surface for thermal contact with a heat transfer fluid, and a flat second surface for thermal contact with an object to be heated or cooled, such as an electronic component. The first surface is provided with a first surface pattern having a plurality of first grooves, and the second surface is provided with a second surface pattern with a plurality of second grooves. The surface patterns may be configured and applied such that the amount of elongation along the first surface produced by application of the first surface pattern substantially corresponds to or offsets the amount of elongation along the second surface produced by application of the second surface pattern, such that the degree of flatness of the first plate prior to formation of the first and second surface patterns will be preserved, maintained or improved.