A module includes a cold plate. Solid-state heat sources are thermally mounted on the cold plate in a chamber defined by the cold plate and a lid. Cooling of the heat sources is enhanced by a dielectric liquid within the chamber. The liquid has a boiling point slightly below the temperatures of "hot" spots, to form small bubbles during operation, which enhance convection flow. The liquid may be a mixture of fluorocarbons of different boiling points. The liquid may contain diamond particles.