its operation in the illustrated embodiment optional cooling medium distribution plate 26 is preferably used to redirect the flow of the cooling medium through apertures 40 in a direction generally perpendicular to surface 36 so that the fluid impinges directly against surface 36 to enhance convective heat transfer and reduce or eliminate stagnant pockets of cooling medium within cavity 38 the expression u201c plenum u201d as used herein means a cavity defined within the heatsink or a portion of a cavity defined within a heatsink that is used for distributing flow of the cooling medium along internal surfaces of the heatsink the cooling medium may comprise generally any suitable liquid such as water or gas such as air that may be effectively utilized for convective heat transfer heatsink members 12 14 are made of a weldable material that has a relatively high thermal conductivity typically at least 10 watts per meter per degree kelvin wm u2212 1 k u2212 1 and more preferably at least 100 watts per meter per degree kelvin suitable materials for heatsink members 12 14 are weldable metals or metal alloys more preferably weldable metals or metal alloys that are resistant to corrosion such as aluminum aluminum alloys copper copper alloys magnesium magnesium alloys and stainless steel although various other materials may be utilized most preferably heatsink members 12 14 are comprised of aluminum because of its relatively high thermal conductivity low.